JPH0564795A - Waste water treatment apparatus - Google Patents

Abstract

PURPOSE:To supply fine gas bubbles of oxidizing gas or metane gas to living waste water with high efficiency by mounting a suction type aerator wherein a porous flowing waste water transfer pipe is provided so as to be exposed to the atmosphere or a suction type aerator wherein the porous flowing waste water transfer pipe is arranged in a gas supply pipe on a waste water treatment apparatus. CONSTITUTION:A suction type aerator 30 wherein a porous flowing waste water transfer pipe is provided so as to be exposed to the atmosphere or a suction type aerator 30 wherein the porous flowing waste water transfer pipe is arranged in a gas supply pipe is mounted on a waste water treatment apparatus 53. As the porous pipe, a ceramic pipe is pref. As a result, the aerator capable of supplying fine gas bubbles of oxidizing gas or methane gas to waste water such as living waste water or industrial waste water with high efficiency can be obtained.

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 equipped with an aerator capable of supplying bubbles such as fine oxidizing gas and methane gas to the wastewater.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Aeration in the wastewater treatment equipment includes a method in which air is pressurized from the tubular or plate-shaped aerator pores installed in the aeration tank into the wastewater and jetted, and the air bubbles are subdivided, and shearing is performed by rotating blades or bubble jets. There are two methods in which air is introduced into the drainage flow in which force has been formed and it is subdivided.

The former method includes those called "air diffuser tube type", "air diffuser plate type", "diffuser cylinder type", etc.
For example, ejecting pressurized air into the drainage from the pores formed in the pipe wall, the slit-shaped pores cut in the rubber disk, and the pores of the cylindrical body made of porous ceramics. It has been attempted to subdivide air bubbles, and the amount of dissolved oxygen in wastewater is said to depend on the amount of fine air bubbles supplied by the pores. In the latter method,
There are those called “rotary vane type”, “jet type”, “single tube aeration type”, and the like. For example, by subdividing air bubbles by colliding an air mass with a rotating vane, gas-liquid two There are methods such as generating a phase jet and subdividing the bubbles in the entrainment process of bubbles and water, and subdividing the bubbles by colliding a two-phase flow of air and water with the protrusions. It is said that the amount of dissolved oxygen depends on the number of rotations of the rotating blades, the velocity of the bubble jet, and the impact velocity of the two-phase flow on the projection. In aeration with an aerator having these functions, basically, necessary adjustments are made depending on the amount of air fed, the number of aerators installed, and the like.

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

However, most of the above-mentioned aeration methods are air diffusion methods by jetting or air bubbles are generated by shearing with the rotating blades and the projections, so that they have the following various drawbacks. For example,
In the jetting method from the diffuser pipe, diffuser plate, and diffuser cylinder, no matter how fine pores are provided there, the surface tension of the bubbles when they eject from the pores results in a diameter of about several mm. However, there is a drawback in that it is impossible to generate smaller bubbles than the above. In addition, as a drawback of such an air diffuser, there is a problem of clogging and an increase in power cost that occur during long-term operation. On the other hand, in the rotary blade system, a high rotational speed is required to generate cavitation, and there are problems of power cost and blade corrosion and vibration that rapidly progress with cavitation. Moreover, in the jet method, in the diameter of the fine bubbles and the generation amount,
No significant advantages over conventional aerators are observed. Further, the method of causing the gas-liquid two-phase flow to collide with the protrusion has a problem that the generation of fine bubbles is small.

In the aerator in the conventional wastewater treatment equipment having the above-mentioned drawbacks and problems, since the amount of fine bubbles produced is small, the residence time of the bubbles in the wastewater is shortened, and the oxygen dissolved in the wastewater is dissolved. The increase in quantity could not be expected. Furthermore, since the diameter and amount of the fine bubbles cannot be easily controlled, there is a problem that the wastewater cannot be efficiently purified.

That is, the aerator as described above has the following problems. ． It is not possible to uniformly generate a large amount of fine bubbles having a diameter of bubbles of 1 mm or less and up to several tens of μm, and it is not possible to achieve dramatic promotion of gas-liquid renewal. ． It is not possible to easily mechanically control the diameter, distribution, and generation amount of the bubbles described above, if necessary. ． Without a stirrer, it is not possible to provide the necessary circulating flow formation or stirring effect in the wastewater treatment device. ． Pressure loss cannot be reduced due to the presence of rotating blades and protrusions. ． When the gas-liquid two-phase flow collides with the rotating blades or protrusions, microorganisms and activated sludge are destroyed, which may hinder the formation and maintenance of the biological environment necessary for purification of sewage. ． The continuous aeration causes clogging and reduces the aeration efficiency, which increases the pressure loss. Therefore, long-term continuous operation and significant reduction in operating costs cannot be achieved. ． The shape of the device, including the aerator and compressor, is large, and there are restrictions on installation, so it cannot be made compact. ． It is difficult to optimally control stirring in the aeration tank, oxidation treatment of COD components, and growth of aerobic microorganisms by controlling the diameter, distribution, and generation amount of bubbles.

[0008]

As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have provided an energy-saving aerator capable of easily supplying fine bubbles to drainage. We developed a wastewater treatment system. That is, the present invention is a wastewater treatment device as described below. A first invention is a wastewater treatment device comprising a suction type aerator in which a porous fluidized wastewater transfer pipe is provided so as to be exposed to the atmosphere, and a second invention is a gas supply pipe. A third aspect of the present invention is a wastewater treatment device comprising a suction type aerator in which a porous fluid drainage transfer pipe is disposed on the inner side. It is a wastewater treatment device comprising a suction type aerator provided with a gas supply pipe. A fourth invention is characterized in that the communication holes of the porous tube are irregular communication holes.
The wastewater treatment device according to any one of the inventions, the fifth invention is characterized in that the porous fluidized wastewater transfer pipe and / or the porous gas supply pipe is a porous ceramic pipe. The wastewater treatment device according to any one of the first to fourth inventions.

A sixth aspect of the present invention is the drainage according to any one of the first to fourth aspects, wherein the porous fluidized waste water transfer pipe and / or the porous gas supply pipe is a porous metal pipe. A seventh aspect of the present invention is the treatment device, wherein the diameter of the communication hole of the porous fluidized waste water transfer pipe or / and the porous gas supply pipe is 5
The wastewater treatment device according to any one of the first to sixth inventions, wherein the porous gas supply pipe and / or the porous fluidized wastewater transfer pipe is The vertical wastewater treatment device, the horizontal wastewater treatment device, or the diagonal wastewater treatment device is the wastewater treatment device according to any one of the first to seventh inventions, and the ninth invention is a porous fluidized wastewater transfer. The wastewater treatment device according to any one of the first to eighth inventions, characterized in that a pipe or / and a porous gas supply pipe are arranged in a siphon.

A tenth aspect of the present invention is characterized in that the porous gas supply pipe and / or the porous fluid drainage transfer pipe is a horizontal or oblique installation type taper pipe. The wastewater treatment apparatus according to any one of the inventions, wherein the eleventh invention has a porous pipe arranged at a maximum negative pressure or minimum positive pressure generation site of a laterally installed or obliquely installed reduced pipe. The wastewater treatment device according to the tenth invention, characterized in that
A second aspect of the invention is the wastewater treatment apparatus according to any one of the eleventh or second or four to nine aspects of the invention, wherein the vertical porous fluidized wastewater transfer pipe is a gradually expanding pipe. A thirteenth aspect of the invention is the first or second aspect, or the fourth to ninth aspect of the invention, characterized in that a porous pipe is arranged at a maximum negative pressure generating site in an upper portion of a fluidized wastewater transfer pipe formed of a vertical type gradually expanding pipe. The wastewater treatment device according to any one of the above, wherein the fourteenth invention is characterized in that a gas supply chamber in the form of a tubular body or a casing is provided around a porous fluidized wastewater supply pipe. Or the wastewater treatment device according to any one of the inventions 4 to 13.

In the above invention, firstly, in the supply of outside air using an irregular porous tube such as ceramics, the suction system has a pressure loss considerably smaller than that of the ejection system. This is because the surface area of the outer peripheral wall surface of the tube is always larger than the surface area of the inner peripheral wall surface due to the presence of the tube thickness, and therefore according to the suction method of the present invention using the porous tube. However, the efficiency of bubble generation in the wastewater will be dramatically improved. In this case, if 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 jet method, the diameter of the pores of the irregular porous tube made of ceramics is
Even if it was reduced to about m, the diameter of the bubbles generated from it was about several mm on average, but the average diameter of the bubbles generated by the suction type aerator according to the present invention was as small as several 100 μm to several 10 μm. Can be converted. Therefore, the contact area between the wastewater and the oxidizing gas bubbles is 10 to 100 of the conventional method.
It can be doubled, and the retention time of bubbles is 1
As a result of being able to increase it by 0 to 100 times, the amount of dissolved oxygen can be dramatically increased.

Fourthly, by controlling the pressure of the gas sent to the flow drainage transfer pipe of the porous pipe, the bubble suction amount can be adjusted without changing the flow rate of the drainage. The efficiency of wastewater treatment can be increased by controlling the amount of bubbles generated. Fifth, the pressure energy required for sucking gas from the porous tube has only to exceed the pressure loss head of the porous tube, and extremely small pressure energy is sufficient. Usually, about 50 cm is sufficient for the head difference. Sixth, the conventional method of performing aeration by colliding with the high-speed rotating blades or the projections has a problem that microorganisms and activated sludge are destroyed, but according to the present invention, such a problem does not occur at all. Seventh, 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 of peeling off the substance to be attached to the inner wall, and as a result, the clogging of the present porous tube is less likely to occur. Further, even if clogging occurs, so-called "backwashing" can be performed by adding a method of reversing the pressure difference between the inside and the outside of the porous tube to recover the clogging.

Eighth, although a compressed air supply device such as a compressor or a blower has been conventionally required, since such a device is a suction type according to the present invention, such a device can be omitted. Further, the porous fluidized waste water supply pipe section can be easily unitized, and for example, By attaching joints at both ends of the transfer tube, or. A unit body is manufactured by mounting a porous fluid drainage supply pipe through a transparent plastic gas supply housing and bonding and sealing the contact part between the through hole of the housing and the transfer pipe. can do. And the above. In the unit body of
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 will also function as a reinforcing member, so damage to the porous ceramic tube will not occur. Can be stopped. As the material of the porous tube, in addition to porous ceramics, porous materials such as porous metal and porous plastic can be used as appropriate, but in any case, the pores of the porous portion become communication holes. Need to be present.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration explanatory view of a wastewater treatment device including a suction type aerator according to the present invention,
The wastewater to be treated first enters the settling tank 52 through the screen 50 and the sand settling tank 51, and then is introduced into the aeration tank 53. In the aeration tank 53, the water in the tank is sucked up by the pump P ₂ , is temporarily stored in the auxiliary tank 54, and is then dropped and returned to the aeration tank 53 again. Aerator 30 according to
Is installed. From the upper end of the aeration tank 53, a part of the aerated water is extracted and introduced into the final settling tank 55,
Next, the supernatant water is introduced into the chlorine sterilization tank 57, from which purified water is taken out. It should be noted that a small amount of the returned sludge 56 is taken out from the bottom of the final settling tank 55, and the aeration tank 5
3 is supplied. P _{1 to} P ₃ are pumps. In the wastewater treatment device, since the suction type aerator made of a porous tube is used as an aerator, first, a large amount of pressure loss energy as in the conventional method using a diffuser tube is not required, and the porous tube is used. Because of the method of sucking the gas into the water through the through, a bubble having a very small diameter is generated instead of a bubble having a large diameter as in the case of the diffuser tube. Therefore, the contact surface area between the bubbles and the wastewater is increased, and the efficiency of gas dissolution in water is greatly improved. As a result, COD and BOD of the wastewater can be reduced with high efficiency.

FIG. 2 is a schematic cross-sectional view of one embodiment of the vertical aerator of the waste water treatment equipment of 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 port, 4
Is a fluid drainage transfer pipe, 4'is a flange, 5 is a fastener (bolt, nut), and 6 is a packing. In the figure, when the drainage flows in the flowing drainage transfer pipe 4 from the direction of the arrow,
In the porous tube 1 part, the gas from the gas introduction port passes through the porous tube wall and is supplied as fine bubbles to the internal flowing waste water (drainage). That is, the inner wall of the porous tube has a negative pressure due to the head of the flowing drainage, and the gas from the gas inlet is sucked as fine bubbles into the flowing drainage through the porous wall.

The relationship between the pore diameter 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 diameters of the generated fine bubbles is about three times the distribution of the pore diameters of the porous tube. However, the measurement condition of FIG. 7 is 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 size is 22 μm,
The amount of flowing water in the liquid waste water transfer pipe was 1.10 l / sec. 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 aerator, each member is easily disassembled, and therefore the assembly is also easy, and the outer diameter of the ceramic porous tube 1 is almost equal to the inner diameter of the narrowest part of the acrylic resin gas supply tube 2. If they are the same, both can be slid and inserted freely, and can be easily assembled and disassembled. In this configuration, the gas supply pipe 2 supports the porous pipe 1 so as to sandwich the porous pipe 1 and is advantageous because it also functions as a reinforcing member for reinforcing a brittle porous pipe such as a ceramic pipe. The vertical aerator of this configuration may be laid down horizontally to form a horizontal type, but in that case, the hydraulic gradient line formed by the pressure difference between the upstream and downstream sides is considered to be low in the downstream aerator. Should be done

Further, if a reducing tube is used, it can be used as it is as a horizontal type. FIG. 3 is a schematic cross-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 port, 4 is a downstream fluid drainage transfer tube, 4'is a flange, 5 is a fastener (a bolt). , Nut), 6 is packing, and 7 is a taper pipe which is also an upstream fluid drainage transfer pipe. In the figure, when the drainage flows in the upstream of the reducing pipe 7 from the direction of the arrow, the negative pressure becomes maximum on the inner wall surface of the rear portion of the reducing pipe 7, and the gas from the gas introduction port is generated in the porous pipe 1 part. After passing through the porous tube wall, fine bubbles are supplied to the internal flowing drainage (drainage). It is preferable that the reduction angle of the taper tube 7 is usually about 10 to 30 degrees.

FIG. 4 shows a conceptual diagram in which the aerator is horizontally placed and siphoned, and gas is sucked as fine bubbles from the porous pipe into the flowing drainage. In the figure, 30 is an aerator according to the present invention, 4 is a fluid drainage transfer pipe, 11 is a drainage storage tank, 12 is an aeration treatment drainage storage tank, HL is a hydraulic gradient line, and H is a head difference. In the figure, when the wastewater is introduced from the wastewater storage tank 11 to the aerator 30 via the fluidized wastewater transfer pipe 4, the outside air becomes fine bubbles due to the head difference H and the hydraulic gradient line HL, and is sucked and supplied into the wastewater. Then, it is fed to the aeration treatment waste water storage tank 12 arranged at the lower position through the fluid waste water 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 this example, since the diameter of the lower portion of the fluid drainage transfer pipe is larger than that of the upper portion, the suction force in the expanded portion of the porous pipe is further enhanced.
In the figure, when the wastewater falls from the upper wastewater storage tank 11 and enters the gradually expanding tube 8, the negative pressure becomes large on the inner wall surface of the porous tube 1 of the gradually expanding tube 8, and the gas from the gas inlet is After passing through the wall of the porous tube 1, fine bubbles are supplied to the internal flowing wastewater (drainage).

FIG. 6 is a schematic sectional view of another embodiment of the vertical aerator. In the figure, a tubular gas supplier 9 having a porous tube 1 is provided inside the fluidized waste water supply pipe 4. According to this example method, the outside air is
After passing through the fluid drainage transfer pipe 4 and passing through the air guide pipe 10 connected to the gas supplier 9, fine bubbles form fine bubbles from the outer wall surface of the porous pipe 1 and are sucked and supplied into the drainage.

As described above, since the suction method using the porous tube is adopted in the present invention, by sucking the external gas from the porous tube such as ceramics, a fine particle having a diameter of several 100 μm to several 10 μm can be introduced into the flowing drainage pipe. It is possible to generate various bubbles and control the amount of bubbles. In the adjustment of the generated bubbles, the amount of bubbles can be increased by increasing the negative pressure in the fluid drainage transfer pipe or by increasing the air pressure in the gas supply pipe, and in order to reduce the bubble diameter. Can be performed by reducing the diameter of the communication hole of the porous tube.

[0023]

As described above in detail in the embodiments and the like, according to the present invention, many excellent effects as described below are exhibited. (1). According to the aerator of the present invention, the pressure loss is considerably smaller than that of the conventional jet type aerator, and the bubble generation efficiency in the fluidized drainage is dramatically improved. (2). According to the present invention, 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 the bubbles generated from there is about several millimeters on average. According to the suction type aerator, the average diameter of the generated bubbles can be reduced from several 100 μm to several 10 μm. Therefore, the contact area between the wastewater and the bubbles such as the oxidizing gas can be extremely increased, and the residence time of the bubbles in the wastewater can be significantly increased, resulting in a dramatic increase in the amount of dissolved oxygen in the wastewater. Can be increased. (4). By controlling the pressure of the gas sent to the flow drainage transfer pipe of the porous pipe, the amount of bubble suction can be adjusted without changing the flow rate of drainage, and by controlling the amount of bubble generation, drainage Higher processing efficiency can be achieved.

(5). The pressure energy required for sucking the gas from the porous tube needs to be higher than the pressure loss head of the porous tube, and an extremely small pressure energy is sufficient, which enables energy saving operation. (6). In the conventional method of performing aeration by colliding with the high-speed rotating blades or the protrusions, 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. (7). As the outside 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 of peeling off the pollutants to be tried. As a result, clogging of the porous tube is less likely to occur. (8). It is not necessary to use a compressed air supply device such as a compressor or a blower as in the conventional method, and only the head difference needs to be secured. (9). The porous fluidized wastewater supply pipe part can be easily unitized, and for example, the porous fluidized wastewater supply pipe is attached to a transparent plastic gas supply housing by penetrating the porous fluidized wastewater supply pipe and the transfer pipe. The unit body can be manufactured by adhering and sealing the contact portion with. When the inner porous tube is made of ceramic in particular, if the outer casing is made of a material having high mechanical strength such as plastic or metal, it can also function as a reinforcing member, so that it is porous. It is possible to prevent damage to the ceramic tube.

[Brief description of drawings]

FIG. 1 is an overall configuration explanatory diagram of a wastewater treatment device including a suction type aerator according to the present invention.

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

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

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

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

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

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

[Explanation of symbols]

1: Ceramic porous tube, 2: Acrylic resin gas supply tube, 2 ': Flange, 3: Gas inlet, 4: Fluid drainage transfer tube, 4': Flange, 5: Fastener (bolt,
Nut :), 6: packing, 7: gradually reducing pipe, 8: gradually expanding pipe, 9: tubular gas supplier, 10: air guiding pipe, 11: drainage storage tank, 12: aeration treatment drainage storage tank, 30: aerator, 50: Screen, 51: Settling tank 52: First settling tank, 53: Aeration tank, 54: Temporary auxiliary tank 55: Final settling tank, 56: Return sludge, 57: Chlorine sterilization tank P _{1 to} P ₃ : Pump HL: Hydraulic gradient Line, H: Head difference

Claims (14)

[Claims] 1. A wastewater treatment apparatus comprising a suction type aerator provided with a porous fluidized wastewater transfer pipe exposed to the atmosphere. 2. A wastewater treatment apparatus comprising a suction type aerator in which a porous fluidized wastewater transfer pipe is arranged inside a gas supply pipe. 3. A wastewater treatment apparatus comprising a suction type aerator in which a porous gas supply pipe is arranged inside a fluid wastewater transfer pipe. 4. The wastewater treatment device according to claim 1, wherein the pores of the porous tube are irregular communication holes. 5. The wastewater treatment apparatus according to claim 1, wherein the porous fluidized wastewater transfer pipe and / or the porous gas supply pipe is a porous ceramic pipe. 6. The waste water treatment apparatus according to claim 1, wherein the porous fluidized waste water transfer pipe and / or the porous gas supply pipe is a porous metal pipe. 7. The wastewater treatment equipment according to claim 1, wherein the diameter of the communication hole of the porous fluidized wastewater transfer pipe or / and the porous gas supply pipe is 500 μm or less. .. 8. The method according to claim 1, wherein the porous gas supply pipe and / or the porous fluid drainage transfer pipe is of a vertical installation type, a horizontal installation type or an oblique installation type. Wastewater treatment equipment described in. 9. The waste water treatment apparatus according to claim 1, wherein the porous fluidized waste water transfer pipe and / or the porous gas supply pipe is arranged in a siphon. 10. The porous gas supply pipe and / or the porous fluidized waste water transfer pipe is a horizontal or oblique installation type reciprocating pipe. Wastewater treatment equipment described in. 11. The wastewater treatment equipment according to claim 10, wherein a porous pipe is arranged at a site where maximum negative pressure or minimum positive pressure is generated in a laterally or diagonally placed reduction pipe. .. 12. The wastewater treatment device according to claim 1, wherein the vertically arranged porous fluidized wastewater transfer pipe is a gradually expanding pipe. 13. A porous pipe is arranged at the maximum negative pressure generation site in the upper part of the fluidized-drainage transfer pipe consisting of a vertical type gradually expanding pipe. The wastewater treatment device according to any one of 9. 14. The drainage according to claim 2, wherein the porous fluidized drainage supply pipe is provided around a gas supply chamber having a tubular body or a casing shape. Processing equipment.