JP2009131827A - Method for treating sewage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance and low-cost sewage treatment technique in which a method for decomposing harmful components contained in sewage is utilized, which is particularly effective for decomposing the harmful components that are organic or inorganic filth in the water and become BOD or COD to make river water or seawater eutrophic or produce oxygen-poor water and which can be applied, specifically, in a septic tank or a treatment site of factory effluent, sewage, excreta, agricultural waste water, cleaning waste water, domestic waste water, etc. <P>SOLUTION: A method for treating sewage comprises the steps of: supplying ozone into sewage 1A as microbubbles 2D having <100 μm average particle size; and irradiating the sewage 1A containing the microbubbles 2D of ozone with ultrasonic waves to pressure-burst the microbubbles 2D. An active hydroxyl group radical is generated by the pressure burst of the microbubbles 2D to efficiently decompose the harmful components. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an organic and inorganic pollution such as factory effluent and domestic effluent, and is used for rivers and seawater as BOD (Biochemical Oxygen Demand) or COD (Chemical Oxygen Demand). The present invention relates to a sewage treatment method for purifying sewage containing harmful components that cause eutrophication and generation of anoxic water.

Conventionally, due to eutrophication due to organic matter and nutrients contained in wastewater from factories and households, red tides and blue tides (anoxic water masses) in closed sea areas such as Tokyo Bay, Ise Bay, Seto Inland Sea, etc. Since the occurrence of this problem, the water pollution control system has been introduced by the Water Pollution Control Law to reduce the pollution load.
However, although the sixth regulation on total water quality is currently being implemented, about 50 red tides occur annually in Tokyo Bay and Ise Bay, and about 100 cases per year in the Seto Inland Sea. The situation continues to occur. In response to these problems, it is expected that the regulation of total water quality will continue to be expanded and regulated.

Biological treatment (activated sludge), coagulation sedimentation, sand filtration, and the like have been used as conventional wastewater treatment techniques. When these technologies are not sufficient, activated carbon, ion exchange, ozone oxidation, ultraviolet oxidation, etc. have been applied as advanced wastewater treatment, but performance is insufficient or equipment costs and operating costs are insufficient for strengthening water quality regulations. The situation was soaring.
In recent years, for example, as described in Japanese Patent Application Laid-Open No. 2004-188239, a method has been proposed in which microbubbles are generated by passing water to which an oxidizing solution is added through a Venturi tube, and are further crushed and decomposed by ultrasonic waves. ing.

JP 2004-188239 A

  However, in the conventional method as described in Japanese Patent Application Laid-Open No. 2004-188239, since the microbubbles manufactured by the Venturi tube are as large as 100 μm or more, the microbubbles are hardly crushed by ultrasonic waves. The sound irradiation method and frequency were not optimized, and the decomposition rate of harmful components was not sufficient.

  An object of the present invention is to provide a high-performance and low-cost wastewater treatment technique that uses a method for decomposing harmful components contained in water, which can cope with recent tightening of water quality regulations. In particular, the present invention is for decomposing harmful components that cause eutrophication of rivers and seawater and generation of anoxic water as BOD and COD due to pollution of at least one of organic and inorganic in water. Specifically, it can be applied to septic tanks and treatment plants such as factory wastewater, sewage treatment, human waste treatment, agricultural wastewater, washing wastewater, and domestic wastewater.

The sewage treatment method according to the present invention supplies ozone into sewage as microbubbles having an average particle size of less than 100 μm, and irradiates the sewage supplied with the ozone microbubbles with ultrasonic waves, thereby the microbubbles. It is characterized by crushing.
In the present invention, ozone is supplied as microbubbles having an average particle size of less than 100 μm, the dissolution rate of ozone into the sewage is increased, and the sewage is irradiated with ultrasonic waves, whereby the microbubbles are easily crushed.
As a result, the generation of active radicals can be promoted, and at least one of organic and inorganic pollution in sewage is caused by eutrophication of rivers and seawater or generation of anoxic water as BOD or COD. The toxic components to be efficiently decomposed by improving the decomposition reaction with the efficiently generated radicals can be efficiently purified.
Here, ozone is supplied with an average particle size of microbubbles of less than 100 μm, preferably 60 μm or less. That is, as the particle size of the microbubbles decreases, the surface area increases, the ascent rate decreases, the ozone gas dissolution rate increases, and the utilization efficiency of ozone can be improved. Furthermore, when the average particle size is less than 100 μm, especially less than 60 μm, negative charging increases, causing phenomena such as coalescence of microbubbles due to repulsive force, adsorption of foreign substances, and collapse by rapid pressurization such as ultrasonic waves. It becomes easy to do. When crushing by rapid pressurization with ultrasonic waves, etc., the ozone gas in the microbubbles instantaneously becomes a high temperature of 1000 ° C. or more due to adiabatic compression, and active hydroxyl radicals (.OH) are generated, causing harmful components. Presumed to cause thermal and oxidative degradation.
In addition, the ozone generator in this invention can utilize well-known various apparatuses and methods. For example, there are silent discharge, electron beam, radiation, ultraviolet light, chemical reaction, electrolytic method, and the like, but industrially, the silent discharge method using air or oxygen as the source gas is advantageous. Moreover, as a method of supplying ozone into the sewage, various known methods such as supplying directly into the sewage with a pump or the like can be used.

In the present invention, the microbubbles of ozone include a micro blade provided with a rotary blade having a gas outlet through which the ozone gas flows out, and a mesh body disposed around the rotary blade so as to cover the rotary blade. It is preferable to use a bubble generator to supply the wastewater.
In this invention, ozone gas flowing out from the gas outlet is supplied into the sewage as ozone bubbles, and the ozone bubbles are partially sheared by the rotating rotor blades, and the ozone bubbles collide with the mesh by the water flow caused by the rotation of the rotor blades. In particular, fine microbubbles having an average particle size of 50 μm or less are generated. Further, the microbubbles can be supplied to the entire sewage by agitation by the rotation of the rotating blades to prevent the sewage from staying.
Accordingly, ozone can be supplied efficiently as fine microbubbles with a simple configuration, low power consumption, and sewage can be purified efficiently.

Further, in the present invention, the ozone microbubbles are formed by forming ozone gas supply means for aspirating ozone gas into the sewage, and forming the bubbles of the aerated ozone gas and the swirl-like multiphase flow of the sewage into the bubbles. It is preferable to use a microbubble generator equipped with a static mixer to be supplied to the sewage.
In the present invention, ozone bubbles, which are bubbles generated by aeration of ozone gas into sewage by the ozone gas supply means, become a vortex-like multiphase flow with sewage by the operation of the static mixer, and the vortex of the multiphase flow and the multiphase flow are Colliding with obstacles in the static mixer, the average particle size is particularly reduced to 50 microns or less, and the void ratio (bubble density) can be increased. Furthermore, microbubbles can be supplied to the whole waste water by stirring with a static mixer, and the stay of waste water can be prevented.
As a result, ozone can be efficiently supplied as fine microbubbles, and sewage can be efficiently purified.

Furthermore, in the present invention, it is preferable that the ultrasonic wave to be irradiated has a frequency of 20 kHz to 150 kHz, preferably 20 kHz to 100 kHz, more preferably 20 kHz to 40 kHz.
In this invention, the lower the frequency of the ultrasonic wave, the more the cavitation becomes, and the crushing of the bubble is likely to occur, and a more remarkable decomposition promoting effect is seen in the frequency range of 20 kHz to 100 kHz, particularly 20 kHz to 40 kHz. In addition, although the effect is obtained even at 20 kHz or less, since it enters the audible range and becomes a tremendous noise, the practicality is low.

And in this invention, the said ultrasonic wave is set as the structure irradiated using the several oscillator arrange | positioned in the state which the direction which irradiates an ultrasonic wave to the said waste water cross | intersects mutually, and an amplitude increases by resonance. It is preferable.
In the present invention, a plurality of oscillators that irradiate ultrasonic waves are used, and the ultrasonic waves of these oscillators are arranged so that the directions of the ultrasonic waves intersect with each other, thereby resonating between one ultrasonic wave and another ultrasonic wave. Occurs, the amplitude of the ultrasonic wave transmitted through the wastewater increases, and the microbubbles are easily crushed.
Thereby, the sewage can be purified more efficiently.

Further, in the present invention, an oscillator that irradiates the ultrasonic waves to the sewage, and an oscillator that is positioned on the irradiation side of the oscillator and is disposed in the sewage in a state in which an axial direction is substantially along an irradiation direction. It is preferable to use a substantially cylindrical draft tube that circulates the sewage in the axial direction by the propulsive force of the irradiated ultrasonic wave, and irradiates the sewage with the ultrasonic wave.
In this invention, a substantially cylindrical draft tube is disposed in the vicinity of the oscillator that irradiates the sewage with ultrasonic waves, that is, on the irradiation side of the oscillator and the axial direction is substantially along the irradiation direction. In addition to preventing diffusion due to reflection, circulation of sewage is obtained by the propulsive force of ultrasonic waves, and the microbubbles are spread over the entire sewage and the microbubbles are easily crushed.
Thereby, the sewage can be purified more efficiently.
Here, the inner diameter of the draft tube is preferably in the range of not less than the diameter of the oscillator and not more than twice the diameter of the oscillator. The length of the draft tube is preferably 10 cm or more. Further, the draft tube is preferably disposed at a distance of 1 cm or more and 2 cm or less from the oscillator.
It is not preferable that the inside diameter of the draft tube be too large in order to prevent scattering and attenuation of ultrasonic waves. For example, the wavelength of an ultrasonic wave having a frequency of 80 kHz is 2 cm, and is 7.5 cm at 20 kHz. And since the point where the ultrasonic wave reflected by the draft tube resonates is a position that is an integral multiple of a half wavelength, it is preferable to design the structure so that this position is accommodated in the draft tube. Note that if the distance between the draft tube and the oscillator is shorter than 1 cm, the circulation of sewage may be impaired.

Furthermore, in the present invention, an oscillator for irradiating the wastewater with the ultrasonic wave, and the ultrasonic wave disposed on the irradiation side of the oscillator and disposed in the wastewater and irradiated on the inner surface side from the oscillator. A substantially cylindrical reflecting / converging mirror having a curved reflecting surface that reflects and reflects the ultrasonic wave in a state of being converged to a predetermined focal point, and configured to irradiate the wastewater with the ultrasonic wave. Is preferred.
In this invention, a curved reflecting surface that reflects ultrasonic waves on the inner surface side and converges to a predetermined focal point in the vicinity of the oscillator that irradiates ultrasonic waves to the sewage, that is, the sewage located on the irradiation side of the oscillator. By arranging the substantially cylindrical reflecting / converging mirror having the above, resonance with the ultrasonic wave occurs, the amplitude of the ultrasonic wave transmitted through the sewage increases, and the microbubbles are easily crushed.
As a result, the waste water can be purified more efficiently.
Note that the reflecting surface is preferably a parabolic shape in a configuration in which, for example, ultrasonic waves emitted from a plurality of oscillators are converged on a focal point. In this configuration, the shape and arrangement position of the parabola of the reflecting / converging mirror may be appropriately designed so that the ultrasonic waves irradiated from the plurality of oscillators are not scattered and the circulation of the sewage is not impaired.

In the present invention, the reflection converging mirror reflects the ultrasonic wave irradiated from the oscillator, and the focal position where the ultrasonic wave converges and the amplitude is amplified is located on the surface of the oscillator. It is preferable to have a configuration that is formed in a substantially cylindrical shape having a reflecting surface that curves in an elliptical spherical shape.
In the present invention, the reflecting surface of the reflecting / converging mirror is curved in an elliptical spherical shape so that the ultrasonic wave irradiated from the oscillator converges at a focal position located on the surface of the oscillator and the amplitude is amplified. The ultrasonic waves are converged and amplified at the other focal position, and the microbubbles are easily crushed.
As a result, the waste water can be purified more efficiently.
Here, it is preferable that the reflection converging mirror which becomes an elliptical spherical reflecting surface has a minor axis of the ellipsoidal sphere that is two to three times the diameter of the oscillator and a major axis corresponding to the resonance point described above. It is preferable to place the resonance point inside the reflecting / converging mirror and to make it coincide with the focal point. In the case of an ultrasonic wave with a frequency of 80 kHz (wavelength 2 cm), since the distance is relatively short, it is preferable to provide a mechanism for finely adjusting the installation height of an elliptical sphere so that the ultrasonic wave can be easily installed at the resonance point.

In the present invention, it is preferable that the sewage supplied with the ozone microbubbles meander through the repetitive flow path and irradiate the ultrasonic wave in a direction intersecting the flow direction.
In the present invention, the microbubbles are crushed by irradiating ultrasonic waves from a side crossing the flow direction, that is, from the side, while meandering the sewage supplied with the microbubbles in a repetitive flow path.
As a result, it is possible to easily extend the time during which the microbubbles are irradiated with the ultrasonic waves, to sufficiently crush the microbubbles, and to obtain a sufficient sewage purification process more efficiently.

[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an apparatus (hereinafter referred to as a sewage treatment apparatus) for carrying out a method for decomposing harmful components in water according to the first embodiment of the present invention. FIG. 1 is also a schematic diagram of an apparatus used in Example 1 described later. FIG. 2 is a perspective view showing a schematic configuration of the microbubble generator.

(Configuration of sewage treatment equipment)
In FIG. 1, 10 is a sewage treatment apparatus, and this sewage treatment apparatus 10 has a function of decomposing harmful components such as organic matter, nutrient salts, human waste, and domestic wastewater contained in the sewage 1A. Such a sewage treatment apparatus 10 surrounds the treatment tank 1 for storing the sewage 1A, the ozone gas supply line 2 for supplying ozone to the sewage 1A, the rotary blade 3 connected to the ozone gas supply line 2, and the rotary blade 3. A wire net 4 as a net-like body, a motor M that rotates the rotary blade 3, and an ultrasonic oscillator 5 that is an oscillator are provided.
The rotating blade 3 and the wire mesh 4 surrounding the rotating blade 3 constitute a microbubble generator 20 that generates the microbubble 2D shown in FIG. In FIG. 1, for convenience of explanation, the microbubbles 2D are described as extremely large bubbles.

The treatment tank 1 has an inflow port (not shown) through which the sewage 1A flows and an outflow port (not shown) through which the treated sewage 1A flows out of the tank. In addition, although the processing tank 1 is shown in the box shape which opens an upper surface for convenience of explanation, it is good to provide a configuration for preventing diffusion of volatile components in the sewage 1A and collecting bubbled ozone as a sealed structure.
The ozone gas supply line 2 includes an ozone generator 2A that generates ozone, and a supply line 2B such as piping for bubbling (aeration) ozone generated by the ozone generator 2A into the sewage 1A.
As shown in FIG. 2, the rotary blade 3 includes a substantially cylindrical rotary shaft 3B having a gas outlet 3A open at the end, and a plurality of blade portions 3C provided substantially radially on the outer peripheral surface of the rotary shaft 3B. And have. The rotating shaft 3B is connected to the output shaft M1 of the motor M and is rotated, and the supply line 2B of the ozone gas supply line 2 is rotatably connected so that the supplied ozone gas can be ejected from the gas outlet 3A. . FIG. 1 shows a state where the output shaft M1 and the supply line 2B are independently supplied to the rotary blade 3 for convenience of explanation.
The wire mesh 4 is formed in a substantially cylindrical shape so as to surround the rotary blade 3 corresponding to the rotation trajectory of the rotary blade 3. The wire mesh 4 is preferably a corrosion-resistant member such as stainless steel that does not easily corrode, or a surface-treated one that is corrosion-resistant. In addition, it is good also as what provided the resin-made nets, such as a fishing net, etc. in the frame member, for example, without being limited to the wire net. The mesh is appropriately set according to the number of blade portions 3C of the rotary blade 3, the rotation speed, and the average particle size of the microbubbles to be generated. If it is too fine, the ozone gas supply pressure needs to be set high. If it is too coarse, the bubbles of ozone are not sufficiently refined and the particle size distribution of the microbubbles is widened. Further, for example, only a portion located around the rotary blade 3 may be a net-like shape, and the upper and lower surfaces in the axial direction may be closed. Moreover, as a mesh body, it is good also as what provided the some fine hole in the steel plate, such as punching metal.

(Operation of sewage treatment)
First, the motor M is rotationally driven to rotate the rotary blade 3, and the sewage 1 </ b> A containing harmful components stored in the treatment tank 1 is stirred. Further, the ozone generator 2A is operated to supply ozone gas to the rotary blade 3 through the supply line 2B. Further, the ultrasonic oscillator 5 is operated to generate ultrasonic waves of 20 kHz to 150 kHz, preferably 40 kHz to 100 kHz, and the sewage 1A is ultrasonically vibrated.
Ozone gas is aerated from the gas outlet 3A of the rotary shaft 3B of the rotary blade 3 by supplying the ozone gas. The aerated ozone gas is supplied to the sewage 1A as relatively coarse bubbles, but the average particle diameter is 100 μm outside the wire mesh 4 due to the flow of the sewage 1A generated by the rotating rotating blades 3 and the collision with the wire mesh 4. Less than, preferably 60 μm or less of microbubbles 2D are supplied in large quantities.
These generated microbubbles 2D are dispersed throughout the sewage 1A by the water flow caused by the rotation of the rotary blades 3. Further, the microbubble 2D is crushed by receiving ultrasonic energy emitted from the ultrasonic oscillator 5. During this crushing, active hydroxyl (OH) radicals are generated, and harmful components of the sewage 1A are thermally decomposed and oxidized to be rendered harmless or significantly reduce their harmfulness.

(Operational effects of the first embodiment)
As described above, in the above embodiment, ozone is supplied as microbubbles 2D having an average particle size of less than 100 μm, the dissolution rate of ozone in the sewage 1A is increased, and the sewage 1A is irradiated with ultrasonic waves so as to be microscopic. The bubble 2D is easily crushed.
For this reason, it is possible to promote the generation of active hydroxyl radicals, and for example, eutrophication of rivers and seawater or generation of anoxic water as BOD or COD due to pollution of at least one of organic and inorganic in the wastewater 1A The causative harmful component can be efficiently decomposed by improving the decomposition reaction with the hydroxyl radicals generated efficiently, and the sewage 1A can be efficiently purified.

The ozone gas flowing out from the gas outlet 3A is supplied into the sewage 1A as ozone bubbles which are relatively coarse bubbles, and the ozone bubbles are partially sheared by the rotating rotating blades 3 and rotated by the rotating blades 3. Ozone bubbles collide with the metal mesh 4 by the water flow caused by the above, and fine microbubbles 2D having an average particle diameter of 50 μm or less are generated. Further, the microbubbles 2D are supplied to the entire sewage 1A by agitation by the rotation of the rotary blades 3 to prevent the sewage 1A from staying.
For this reason, with simple structure, power consumption is low, ozone can be supplied efficiently as the fine microbubble 2D, and the sewage 1A can be purified efficiently.

Furthermore, the frequency of the ultrasonic wave to be irradiated is set to 20 kHz to 150 kHz, preferably 40 kHz to 100 kHz.
For this reason, it becomes an ultrasonic wave close to the natural frequency of the microbubbles 2D of ozone, the microbubbles 2D are easily crushed, and the sewage 1A can be efficiently purified by the hydroxyl radicals that are efficiently generated.

In the first embodiment, as shown in FIG. 1, the configuration is not limited to the configuration in which ozone gas is ejected from the rotating shaft 3 </ b> B, and the end of the supply line 2 </ b> B serves as a gas outlet 3 </ b> A and opens in the wire mesh. It may be disposed at a position where it does not interfere with rotation, and ozone may be bubbled.
In the first embodiment, the sewage 1A is not limited to batch processing, and gradually supplies untreated sewage 1A to the treatment tank 1 and continuously flows out the overflow as treated treated water. It is good also as processing.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a schematic view showing a sewage treatment apparatus according to the second embodiment of the present invention. FIG. 3 is also a schematic diagram of the apparatus used in Examples 2 to 4 described later.
And description is abbreviate | omitted or simplified about the structure same as 1st embodiment.

(Configuration of sewage treatment equipment)
In FIG. 3, 30 is a sewage treatment apparatus, and this sewage treatment apparatus 30 is similar to the treatment tank 1, ozone gas supply line 2, rotary blade 3, wire mesh 4, motor M, and ultrasonic oscillator as in the first embodiment. 5 and an ultrasonic treatment tank 6.
Similar to the treatment tank 1, the ultrasonic treatment tank 6 is configured to store the sewage 1 </ b> A. The ultrasonic treatment tank 6 is connected to the treatment tank 1 via a circulation path 7 so that the sewage 1A stored in the treatment tank 1 can be circulated. The circulation path 7 has a circulation pump 7 </ b> A, a delivery line 7 </ b> B that allows the wastewater 1 </ b> A stored in the treatment tank 1 to flow into the ultrasonic treatment tank 6, and the wastewater 1 </ b> A stored in the ultrasonic treatment tank 6 to the treatment tank 1. A return line 7C for returning.
The ultrasonic treatment tank 6 is provided with an ultrasonic oscillator 5. Then, the ultrasonic oscillator 5 irradiates ultrasonic waves to the sewage 1A in which the microbubbles 2D are mixed and flowed into the ultrasonic processing tank 6 from the processing tank 1.

(Operation of sewage treatment)
The same processing as in the first embodiment is omitted.
In the sewage treatment apparatus 30 of the second embodiment, the ultrasonic oscillator 5 is operated and the circulation pump 7A of the circulation path 7 is operated. By the operation of the circulation pump 7A, the sewage 1A supplied with the microbubbles 2D in the treatment tank 1 flows into the ultrasonic treatment tank 6 through the delivery line 7B.
And the microbubble 2D is crushed with the ultrasonic wave irradiated from the ultrasonic oscillator 5, and the sewage 1A is purified.

(Operational effects of the second embodiment)
According to the configuration of the second embodiment, the processing tank 1 and the ultrasonic processing tank 6 can be arranged in a vertically positioned state, and therefore can be applied even when the site area is small, for example. Furthermore, it is necessary to design the volume of the processing tank 1 to be relatively small with a small amount to be processed, and even when arrangement interference between the ultrasonic oscillator 5 and the ozone gas supply line 2 or the motor M occurs. Since it is a tank structure, the freedom degree of design is obtained.

[Third embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 4 is a schematic view showing a sewage treatment apparatus according to the third embodiment of the present invention. FIG. 4 is also a schematic diagram of the apparatus used in Example 5 described later.
The description of the same configuration as that of the first embodiment and the second embodiment is omitted or simplified.

The sewage treatment apparatus 40 of the third embodiment shown in FIG. 4 is provided with a plurality of ultrasonic oscillators 5 in the ultrasonic treatment tank 6 in the sewage treatment apparatus 30 of the second embodiment shown in FIG.
These ultrasonic oscillators 5 are arranged in the ultrasonic treatment tank 6 so that the directions in which the ultrasonic waves are applied intersect, for example, are orthogonal.
In the sewage treatment apparatus 40 shown in FIG. 4, the ultrasonic wave irradiated from the plurality of ultrasonic oscillators 5 increases the amplitude of the ultrasonic wave transmitted through the sewage 1A due to resonance, and the crushing efficiency of the microbubbles 2D is improved. . Thereby, the microbubble 2D is efficiently crushed by the increase of the ultrasonic energy to the sewage 1A, and the sewage 1A can be purified to a higher degree.
Although the plurality of ultrasonic oscillators 5 are provided in the ultrasonic treatment tank 6, for example, as in the first embodiment, the plurality of ultrasonic oscillators 5 are provided in the treatment tank 1 without using the ultrasonic treatment tank 6. May be.

[Fourth embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a schematic view showing a sewage treatment apparatus according to the fourth embodiment of the present invention. FIG. 5 is also a schematic diagram of the apparatus used in Example 6 to be described later.
The description of the same configuration as that of the first embodiment to the third embodiment is omitted or simplified.

The sewage treatment apparatus 50 of the fourth embodiment shown in FIG. 5 is obtained by providing the draft tube 8 in the sewage treatment apparatus 30 of the first embodiment shown in FIG.
The draft tube 8 is located in the irradiation side of the ultrasonic oscillator 5 and is disposed in the processing tank 1 so that the axial direction is substantially along the irradiation direction. The draft tube 8 preferably has an inner diameter that is not less than the diameter of the ultrasonic oscillator 5 and not more than twice the diameter of the ultrasonic oscillator 5. The length of the draft tube 8 is preferably 10 cm or more. Further, the draft tube 8 is preferably disposed at a distance of 1 cm or more and 2 cm or less from the ultrasonic oscillator 5.
Here, it is not preferable that the inside diameter of the draft tube be too large in order to prevent scattering and attenuation of ultrasonic waves. For example, the wavelength of an ultrasonic wave having a frequency of 80 kHz is 2 cm, and is 7.5 cm at 20 kHz. And since the point where the ultrasonic wave reflected by the draft tube 8 resonates is a position that is an integral multiple of a half wavelength, it is preferable to design the structure so that this position is accommodated in the draft tube 8. Note that if the distance between the draft tube 8 and the ultrasonic oscillator 5 is shorter than 1 cm, the circulation of the sewage 1A may be impaired.
In the sewage treatment apparatus 50 shown in FIG. 5, the ultrasonic wave irradiated from the ultrasonic oscillator 5 by the draft tube 8 does not diffuse into the entire sewage 1A, and the ultrasonic energy density is high in the sewage 1A in the draft tube 8. And the microbubbles 2D are efficiently crushed. Furthermore, since the ultrasonic energy is difficult to diffuse, the circulation of the sewage 1A in the treatment tank 1 can be strengthened by the ultrasonic driving force.
Thus, the sewage 1 </ b> A can be purified with high efficiency and high efficiency with a simple configuration in which the draft tube 8 is provided.

[Fifth embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a schematic view showing a sewage treatment apparatus according to the fifth embodiment of the present invention. FIG. 6 is also a schematic diagram of the apparatus used in Example 7 described later.
The description of the same configuration as that of the first embodiment to the fourth embodiment is omitted or simplified.

The sewage treatment apparatus 60 of the fifth embodiment shown in FIG. 6 is an ellipse that is a reflective converging mirror that causes the sewage treatment apparatus 30 of the second embodiment shown in FIG. 3 to reflect ultrasonic waves and converge at a predetermined focal position. A spherical reflecting / converging mirror 9 is provided.
The elliptical spherical reflecting / converging mirror 9 is formed in a substantially elliptical spherical shape which is a substantially cylindrical shape, and is disposed in the ultrasonic processing tank 6 on the irradiation side of the ultrasonic oscillator 5. The elliptic sphere reflecting / converging mirror 9 has an elliptical spherical reflecting surface 9B on the inner surface side, which is a curved surface that reflects ultrasonic waves and converges them to a first focal point 9A that is a predetermined focal point. The elliptic sphere reflecting / converging mirror 9 is configured such that the second focal point 9 </ b> C is positioned on the surface of the ultrasonic oscillator 5.
Here, it is preferable that the ellipsoidal reflecting / reflecting mirror 9 is set so that the minor axis of the ellipsoidal sphere is two to three times the diameter of the ultrasonic oscillator 5 and the major axis is matched to the resonance point described in the fourth embodiment. It is preferable to place the resonance point inside the ellipsoidal reflecting / converging mirror 9 and to coincide with the first focal point 9A. In the case of an ultrasonic wave with a frequency of 80 kHz (wavelength 2 cm), since the distance is relatively short, it is preferable to provide a mechanism for finely adjusting the installation height of an elliptical sphere so that the ultrasonic wave can be easily installed at the resonance point.
In the sewage treatment apparatus 60 shown in FIG. 6, since the second focal point 9 </ b> C is located on the surface of the ultrasonic oscillator 5, the ultrasonic wave irradiated from the ultrasonic oscillator 5 by the ellipsoidal reflecting / converging mirror 9 is The focal point 9A converges to increase the amplitude, the ultrasonic energy density is increased inside the ellipsoidal reflection converging mirror 9, and the microbubbles 2D are efficiently crushed. Furthermore, since the ultrasonic energy is difficult to diffuse, the circulation of the sewage 1A in the ultrasonic treatment tank 6 can be strengthened by the propulsive force of the ultrasonic wave, and no stirring device or the like is provided in the ultrasonic treatment tank 6. Both can prevent the sewage 1A from staying.
Accordingly, the sewage 1A can be purified with high efficiency and high efficiency with a simple configuration in which the elliptic sphere reflecting / converging mirror 9 is provided.

[Sixth embodiment]
Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings.
FIG. 7 is a schematic view showing a sewage treatment apparatus according to the sixth embodiment of the present invention. FIG. 7 is also a schematic diagram of the apparatus used in Example 8 to be described later.
The description of the same configuration as that of the first embodiment to the fifth embodiment is omitted or simplified.

The sewage treatment apparatus 70 of the sixth embodiment shown in FIG. 7 includes a radial reflection / convergence mirror 90 that is a reflection / convergence mirror instead of the elliptic sphere reflection / convergence mirror 9 of the sewage treatment apparatus 60 of the fifth embodiment shown in FIG. In addition to the use, a plurality of ultrasonic oscillators 5 are provided.
The radial reflection converging mirror 90 is formed in a substantially truncated cylindrical shape that is substantially cylindrical, and is located on the irradiation side of the plurality of ultrasonic oscillators 5 arranged on the same surface of the ultrasonic processing tank 6. 6 is disposed. The radial reflection converging mirror 90 includes a curved reflecting surface 90B, which is a reflecting surface that is curved into a radiation shape that reflects the ultrasonic waves irradiated from the plurality of ultrasonic oscillators 5 and converges to a predetermined focal point 90A. It is on the inner surface side. As for the radial reflection converging mirror 90, as in the fifth embodiment, the edge on the side to be expanded is not excessive so as not to impair the circulation of the sewage 1A in the ultrasonic treatment tank 6 by the ultrasonic driving force. It is preferable to arrange it in a state of being separated from the sonication tank 6.
In the sewage treatment apparatus 70 shown in FIG. 7, similarly to the sewage treatment apparatus 60 shown in FIG. 6, the ultrasonic wave converges at the focal point 90 </ b> A to increase the amplitude, and the ultrasonic energy density is increased inside the radial reflection converging mirror 90. The microbubbles 2D can be efficiently crushed and the circulation of the sewage 1A in the ultrasonic treatment tank 6 can be strengthened by the propulsive force of ultrasonic waves by preventing the diffusion of ultrasonic energy. Therefore, the sewage 1A can be purified with higher efficiency and higher efficiency with a simple configuration in which the radial reflection converging mirror 90 is provided.

[Seventh embodiment]
Hereinafter, a seventh embodiment of the present invention will be described with reference to the drawings.
FIG. 8 is a schematic view showing a sewage treatment apparatus according to the seventh embodiment of the present invention. FIG. 8 is also a schematic diagram of the apparatus used in Example 9 to be described later.
The description of the same configuration as that of the first embodiment to the sixth embodiment is omitted or simplified.

In the sewage treatment apparatus 80 of the seventh embodiment shown in FIG. 8, a plurality of partition plates 6E are provided in the ultrasonic treatment tank 6 in the sewage treatment apparatus 30 of the second embodiment shown in FIG. A plurality of ultrasonic oscillators 5 are provided to meander through the tank 6 and irradiate ultrasonic waves to the circulating sewage 1A.
The ultrasonic treatment tank 6 is provided in a plurality of layers so that a plurality of partition plates 6E are alternately formed in a comb shape substantially in parallel, and is configured in a hierarchical shape. This layer forms a repetitive flow path in a state where two or more layers, that is, the sewage 1A flowing in from the delivery line 7B is circulated once in a reciprocating manner until it is returned in the return line 7C. Note that the ultrasonic treatment tank 6 is not limited to a configuration in which the ultrasonic treatment tank 6 is layered in the vertical direction, and may be configured to be partitioned in the horizontal direction. Furthermore, the partition plate 6E is not limited to a planar configuration, and may have any repetitive flow path through which the sewage 1A meanders, such as a configuration that bends in a wave shape or a sawtooth shape. The ultrasonic treatment tank 6 is provided with a plurality of ultrasonic oscillators 5 positioned between the partition plates 6E. These ultrasonic oscillators 5 are arranged in a state in which ultrasonic waves are irradiated from the side with respect to the flow direction flowing between the partition plates 6E.
In the sewage treatment apparatus 80 shown in FIG. 8, the partition plate 6E causes the sewage 1A to be circulated with the treatment tank 1 to meander through the ultrasonic treatment tank 6 while being irradiated with ultrasonic waves. The microbubble 2D can be efficiently crushed by mixing and ultrasonic vibration. Therefore, the sewage 1A can be purified at a higher level.

[Eighth embodiment]
Hereinafter, an eighth embodiment of the present invention will be described with reference to the drawings.
FIG. 9 is a schematic view showing a sewage treatment apparatus according to the eighth embodiment of the present invention. FIG. 9 is also a schematic diagram of the apparatus used in Example 10 described later.
The description of the same configuration as that of the first embodiment to the seventh embodiment is omitted or simplified.

The sewage treatment apparatus 100 of the eighth embodiment shown in FIG. 9 is circulated as a microbubble generator having a static mixer 110 as the microbubble generator 20 in the sewage treatment apparatus 10 of the first embodiment shown in FIG. A type microbubble generator 120 is used.
The circulation type microbubble generator 120 generates a turbulent flow in a circulation line 121 that is a pipe having a circulation pump 7A and both ends connected to the treatment tank 1, and sewage 1A that is provided in the circulation line 121 and circulates. And a static mixer 110. The supply line 2B of the ozone gas supply line 2 is connected to the circulation line 121 on the upstream side of the circulation pump 7A in the flowing direction of the sewage 1A. As long as the ozone supply position is upstream of the static mixer 110, it may be downstream of the circulation pump 7A.
In the sewage treatment apparatus 100 shown in FIG. 9, the sewage 1A in the treatment tank 1 is circulated to the treatment tank 1 through the circulation line 121 by driving the circulation pump 7A, and ozone gas is supplied from the supply line 2B during the circulation. Aerated. The sewage 1A mixed with ozone bubbles of relatively coarse bubbles by this aeration is refined to some extent when flowing through the circulation pump 7A, and further inside the static mixer 110 when flowing through the operating static mixer 110. , Collide with an obstacle (for example, an internal rod-like or plate-like projection), is refined into microbubbles 2D having an average particle size of less than 100 μm, particularly 60 μm or less, and flows into the processing tank 1. Then, the microbubbles 2 </ b> D in the sewage 1 </ b> A that has flowed into the treatment tank 1 are crushed by the ultrasonic waves emitted from the ultrasonic oscillator 5. The crushing of the microbubbles 2D generates active hydroxyl radicals, and the sewage 1A is sufficiently purified.

Hereinafter, the result of having performed purification processing of sewage using various device composition is explained.
Example 1
As the treatment apparatus, the sewage treatment apparatus 10 shown in FIG. 1 was used.
The treatment condition was that 8 liters of water flowed into the treatment tank 1, the rotary blade 3 of the microbubble generator 20 was rotated at 3000 rpm, and ozone was supplied at 0.112 mmol / min. The microbubbles had an average particle size of about 50 μm.
From the horn type ultrasonic oscillator 5, ultrasonic waves were applied to water at a frequency of 25 kHz.
Thereafter, methylene blue simulated as a harmful component was added under the condition of a concentration of 0.1 mmol / L. The time when this methylene blue was added was defined as the start of sewage treatment.
A methylene blue aqueous solution was collected every 10 minutes after the start of sewage treatment, and the concentration of methylene blue remaining was measured by gas chromatography. The residual rate was calculated with the amount of methylene blue at the start of sewage treatment being 100%.

(Example 2)
A sewage treatment apparatus 30 shown in FIG. 3 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was a washing tank type.

(Example 3)
A sewage treatment apparatus 30 shown in FIG. 3 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was a washing tank type and the frequency of the ultrasonic wave was 40 kHz.

Example 4
A sewage treatment apparatus 30 shown in FIG. 3 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was a washing tank type and the frequency of the ultrasonic wave was 100 kHz.

(Example 5)
A sewage treatment apparatus 40 shown in FIG. 4 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was a combination of a horn type and a cleaning tank type.

(Example 6)
A sewage treatment apparatus 50 shown in FIG. 5 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the draft tube 8 was installed near the ultrasonic oscillator 5 in Example 1.

(Example 7)
A sewage treatment apparatus 60 shown in FIG. 6 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was of a washing tank type and the elliptical spherical reflecting mirror 9 was installed above the ultrasonic oscillator 5.

(Example 8)
A sewage treatment apparatus 70 shown in FIG. 7 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was of a washing tank type and the radial reflection converging mirror 90 was installed above the ultrasonic oscillator 5.

Example 9
As the treatment apparatus, a sewage treatment apparatus 80 shown in FIG. 8 was used.
The processing conditions were the same as in Example 1 except that the ultrasonic oscillator 5 in Example 1 was a cleaning tank type and the ultrasonic irradiation portion was a hierarchical repetitive flow path.

(Example 10)
A sewage treatment apparatus 100 shown in FIG. 9 was used as the treatment apparatus.
The processing conditions were the same as in Example 1 except that the frequency of the ultrasonic wave in Example 1 was 80 kHz, and the static mixer 110 was operated so that the average particle size was 50 μm as the generation of microbubbles 2D. .

(Example 11)
As the treatment apparatus, the sewage treatment apparatus 10 shown in FIG. 1 was used.
The treatment condition was that 8 liters of water flowed into the treatment tank 1, the rotary blade 3 of the microbubble generator 20 was rotated at 3000 rpm, and ozone was supplied at 0.112 mmol / min. The microbubbles had an average particle size of about 50 μm.
From the horn type ultrasonic oscillator 5, ultrasonic waves were applied to water at a frequency of 20 kHz.
Thereafter, methylene blue simulated as a harmful component was added under the condition of a concentration of 0.1 mmol / L. The time when this methylene blue was added was defined as the start of sewage treatment.
A methylene blue aqueous solution was collected every 10 minutes after the start of sewage treatment, and the concentration of methylene blue remaining was measured by gas chromatography. The residual rate was calculated with the amount of methylene blue at the start of sewage treatment being 100%.

(Comparative Example 1)
As the treatment apparatus, the sewage treatment apparatus 10 shown in FIG. 1 was used.
The processing conditions were the same as in Example 1 except for the conditions in which ultrasonic irradiation was not performed in Example 1.

(Comparative Example 2)
As the treatment apparatus, the sewage treatment apparatus 10 shown in FIG. 1 was used.
The processing conditions were the same as in Example 1 except that the microbubble generator 20 was not operated and ozone was aerated from a commonly used diffuser. In addition, the average particle diameter of the ozone bubble in this comparative example 2 was about 800 micrometers.

(result)
The results of the remaining rates of Examples 1 to 11 and Comparative Examples 1 and 2 are shown in FIGS.
As shown in FIG. 10, it can be seen from the comparison between Example 1 and Comparative Examples 1 and 2 that the ultrasonic irradiation promotes the decomposition in Example 1.
From the results of Example 1 and Example 2, it can be seen that the decomposition promotion effect is higher at 25 kHz in the method using the ultrasonic treatment tank 6 shown in FIG. 3 than at the horn type frequency of 25 kHz.
Furthermore, it can be seen from the comparison between Example 3 and Example 10 that the microbubble generation method using the static mixer 110 has a higher decomposition promoting effect than the configuration using the rotary blade 3.

Further, as shown in FIG. 11, it can be seen from the comparison between Examples 2 to 4 that the ultrasonic frequency is higher in the order of 25 kHz> 40 kHz> 100 kHz and the decomposition promoting effect is high.
Furthermore, as shown in FIG. 12, from the comparison of Examples 1, 5, and 6, decomposition is promoted in the order of a configuration in which two ultrasonic oscillators 5 are provided (horn type + tank type)> a configuration in which a draft tube 8 is used. It turns out that an effect is high.
Further, as shown in FIG. 13, according to comparison between Examples 2 and 7 to 9, the decomposition promoting effect is high in the order of the elliptical spherical reflecting / converging mirror 9> the radial reflecting / converging mirror 90> the hierarchical structure that forms the meandering flow path. I understand.
In Example 1 treated with ultrasonic waves with a frequency of 25 kHz and Example 11 treated with ultrasonic waves with a frequency of 20 kHz, as shown in FIGS. 10 and 14, there is almost no difference in the residual rate of harmful substances. It is recognized that there is an equivalent high decomposition promoting effect.

It is the schematic diagram which showed the sewage treatment apparatus which concerns on 1st embodiment of this invention. It is a perspective view which shows schematic structure of the microbubble generator in said 1st embodiment. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 2nd embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 3rd embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 4th embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 5th embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 6th embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 7th embodiment of this invention. It is a schematic diagram which shows the sewage treatment apparatus which concerns on 8th embodiment of this invention. It is a graph which shows the residual rate of a hazardous | toxic substance as a result of the wastewater treatment in this invention. It is a graph which shows the residual rate of a hazardous | toxic substance as a result of the wastewater treatment in this invention. It is a graph which shows the residual rate of a hazardous | toxic substance as a result of the wastewater treatment in this invention. It is a graph which shows the residual rate of a hazardous | toxic substance as a result of the wastewater treatment in this invention. It is a graph which shows the residual rate of a hazardous | toxic substance as a result of the wastewater treatment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30, 40, 50, 60, 70, 80, 100 ... Sewage treatment apparatus 1A ... Sewage 2 ... Ozone gas supply line 2D ... Micro bubble 3 ... Rotating blade 3A ... Gas outlet 4 ... Wire mesh 5 …… Ultrasonic oscillator 8 …… Draft tube 9 …… Ellipsoidal reflecting / converging mirror 9A that is a reflecting / converging mirror 9A · First focal point that is a focal point 9B · Reflecting surface 9C · Second focal point that is a focal point 90 ··· Reflecting / converging mirror Radial reflective converging mirror 90A ... focal point 90B ... curved reflective surface which is a reflective surface

Claims (11)

In the sewage, ozone is supplied as microbubbles having an average particle size of less than 100 μm,
A sewage treatment method, wherein the sewage supplied with the ozone microbubbles is irradiated with ultrasonic waves to crush the microbubbles. The sewage treatment method according to claim 1,
The microbubble of ozone uses a microbubble generator provided with a rotating blade having a gas outlet for flowing out the ozone gas, and a mesh body disposed around the rotating blade so as to cover the rotating blade. The wastewater treatment method is characterized by being supplied to the wastewater. The sewage treatment method according to claim 1,
The ozone microbubble comprises ozone gas supply means for aspirating ozone gas into the wastewater, and a static mixer for forming bubbles of the aerated ozone gas and a vortex-like multiphase flow of the wastewater to refine the bubbles. Using the provided microbubble generator, the wastewater is supplied to the wastewater. A sewage treatment method according to any one of claims 1 to 3,
The ultrasonic wave to be irradiated has a frequency of 20 kHz to 150 kHz. The sewage treatment method according to claim 4,
The ultrasonic wave to irradiate has a frequency of 20 kHz to 40 kHz. A sewage treatment method according to any one of claims 1 to 5,
The sewage treatment method, wherein the ultrasonic waves are radiated using a plurality of oscillators arranged in such a manner that the directions of irradiating the sewage with ultrasonic waves intersect each other and the amplitude increases by resonance. A sewage treatment method according to any one of claims 1 to 5,
An oscillator that irradiates the wastewater with the ultrasonic wave, and the ultrasonic wave that is located in the irradiation side of the oscillator and that is disposed in the wastewater in a state in which the axial direction is substantially along the irradiation direction. A substantially cylindrical draft tube that circulates the sewage in the axial direction by the propulsive force of the sewage, and irradiates the sewage with the ultrasonic wave. A sewage treatment method according to any one of claims 1 to 5,
An oscillator for irradiating the sewage with the ultrasonic wave, and an ultrasonic wave that is disposed on the irradiation side of the oscillator and is disposed in the sewage and reflects the ultrasonic wave radiated from the oscillator on the inner surface side. A sewage treatment method comprising: irradiating the sewage with the ultrasonic wave using a substantially cylindrical reflecting / converging mirror having a curved reflecting surface that reflects the light to converge to a predetermined focal point. A sewage treatment method according to claim 8,
A plurality of the oscillators are disposed,
The sewage treatment method, wherein the reflection converging mirror is formed in a parabolic shape in which a reflection surface converges an ultrasonic wave irradiated from the plurality of oscillators to a predetermined focus. A sewage treatment method according to claim 8,
The reflection converging mirror is bent into an elliptical spherical shape in a state where the focal point where the ultrasonic wave irradiated from the oscillator is reflected and the ultrasonic wave converges and the amplitude is amplified is located on the surface of the oscillator. A sewage treatment method characterized by being formed in a substantially cylindrical shape having a reflecting surface. A sewage treatment method according to any one of claims 1 to 10,
The sewage treatment method, characterized in that the sewage supplied with the ozone microbubbles meanders in a repetitive flow path and irradiates the ultrasonic wave in a direction crossing the flow direction.

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