JP4870942B2 - Method and apparatus for dispersing fats and oils in wastewater containing fats and oils - Google Patents

Description

  The present invention relates to a method for treating fat and oil-containing wastewater, and more particularly to a method and apparatus that can smoothly treat wastewater without separating and collecting fats and oils contained in the wastewater.

  It is considered preferable that oil-containing wastewater is separated and removed before being biologically treated. However, in order to separate and remove oils and fats in wastewater, a large-scale device such as a pressurized flotation device is necessary, and it takes time, labor, and cost to operate the device and to treat the separated material. It often happens that the operation of facilities is hindered.

  Conventionally, as a method for treating fats and oils in wastewater, a method of biologically treating the oils and fats by dispersing them in wastewater without removing the fats and oils (see Patent Document 1, pages 1 to 3, and FIG. 1) has been devised. In this method, as shown in FIG. 8, a treatment tank 100 for temporarily storing wastewater, and an inlet opening is provided at a position slightly lower than the surface of the treatment liquid inside the treatment tank 100, and sequentially descends from the inlet opening, A pipe body 101 having a pipe passage bent so as to be inclined upward toward an outlet opening located in the processing liquid, and an air blowing means in which an air pipe 102 is connected to a relatively low position in the upward inclination of the pipe body 101 103 and a blower 104 for sending air to the air blowing means 103.

  When the air is blown into the tubular body 101 by the air blowing means 103, the processing liquid is sucked from the inlet opening near the water surface of the tubular body 101, and the processing liquid is discharged from the outlet opening. Inside the tube 101, the oils and fats sucked together with the treatment liquid are vigorously mixed and stirred by the air bubbling action to be refined.

  On the other hand, regarding the particle size distribution of fats and oils, in order to be decomposed well by microorganisms such as activated sludge in a wastewater treatment facility, a technique for reducing the particle size of fats and oils and dispersing them in wastewater is studied (Patent Document 2). , See pages 1-5). According to this study, the emulsifier is added continuously or intermittently to the fat-containing wastewater, and the fats and oils are dispersed so that those having a particle diameter in the range of 1 to 100 μm are contained in 80% or more of the fat content. It has been found that biological treatment is performed well, and the method is disclosed.

Japanese Patent Publication No. 6-77755 JP 2001-259673 A

  However, in the apparatus of Patent Document 1, since only mixing and stirring by air is performed, the degree of dispersion of fats and oils in wastewater is low, hardly emulsified and dispersed, and fats and oils in wastewater are not easily decomposed by living organisms. There is a problem.

  In order to solve such problems, in the method of Patent Document 2, in order to promote emulsification and dispersion of fats and oils, a dispersant is added to adjust the particle size to be suitable for biological treatment. The addition of the dispersant has caused a new problem that the running cost is increased and the operation cost is increased.

  The present invention has been made in view of the above-described problems of the prior art, and emulsifies and disperses oils and fats in wastewater to a particle size suitable for biological treatment without adding a chemical solution such as a dispersant. It is an object of the present invention to provide a method and an apparatus capable of smoothly treating wastewater without separating and collecting oils and fats contained therein.

Fats dispersion method of the present invention, by rotating the stirring blade at oil-containing waste water, see write winding fats and oils on the water surface causes a convection having a downward flow in the oil-containing waste water by the rotation of the stirring拌羽 Further, due to the negative pressure generated at the center of rotation of the stirring blade through an air pipe having one end opened at the center of the stirring blade and the other end opened on the water surface of the oil-containing wastewater. Air is drawn into the oil-containing wastewater from outside, bubbles are supplied into the oil-containing wastewater, and the oils are dispersed in the oil-containing wastewater.

The fats and oils dispersing apparatus of the present invention includes a water tank provided with an introduction pipe for introducing oil-containing waste water and a transfer pipe for transferring the dispersed waste water, and a draft tube having upper and lower openings provided in the water tank. When a downward flow generator for generating a downward flow by the rotation of the stirring blade provided in the lower side of the draft tube, the stirring blade of the central opening in the one end with the other end on the water surface of the fat-containing wastewater It has an air pipe which introduces air from the opened outside , and includes the following configuration as a preferred embodiment.

  The downflow generation device is a fine bubble generation device that generates a fine bubble while generating air under pressure by generating a negative pressure at the center of rotation of the stirring blade.

  The suction side opening of the draft tube is configured to follow fluctuations in the water level in the water tank.

  The present invention has the above-described configuration, and the following excellent effects can be obtained.

  (1) Oils and fats floating on the water surface or in water can be introduced to the stirring blades by the downward flow of the convection generated by the rotation of the stirring blades. It can be emulsified and dispersed to a median diameter of about 45 μm.

  (2) By drawing air from the outside using negative pressure generated in the rotation center and supplying bubbles into the oil-containing wastewater, a strong convection is formed in the oil-containing wastewater, It can be reliably pulled into the center of rotation and emulsified and dispersed to a median diameter of about 30 μm.

  (3) Further, while generating a negative pressure at the rotation center of the stirring blade below the water tank provided with the introduction pipe for introducing the fat-containing waste water and the transfer pipe for transferring the treated water, the air is self-supplied. By installing a microbubble generator for generating microbubbles, and providing a draft tube so that convection is generated in the water tank above the microbubble generator, convection is surely caused in the water tank, and more generally All the fat-and-oil containing wastewater receives the shearing force of the stirring blade, whereby the fats and oils can be emulsified and dispersed to a median diameter of about 20 μm.

  In the present invention, the median diameter is a particle diameter corresponding to a cumulative 50% in the particle diameter distribution. It is suitable for biological treatment when the median diameter is 1 to 100 μm, but the smaller the median diameter, the better. In the present invention, oils and fats are animal and vegetable oils and mineral oils.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, it is needless to say that the present invention is not limited to the embodiments. FIG. 1 is a schematic diagram showing a first embodiment which is a reference embodiment of the present invention. FIG. 2 is a schematic view showing a second embodiment of the present invention. FIG. 3 is a schematic view showing a third embodiment of the present invention. FIG. 4 is a schematic view showing another form of the draft tube in the third embodiment.

[Embodiment 1]
In FIG. 1, reference numeral 1 denotes a water tank that retains fat and oil-containing waste water, and reference numeral 10 denotes a side wall in the water tank 1. Above the water tank 1, an introduction pipe 2 for introducing the oil-containing waste water 4 into the water tank 1 is disposed, and the transfer pipe 3 for transferring the treated water is below the water level in the water tank 1 so as to keep the water level constant. It communicates with the side. A stirring blade 5 is provided at the bottom of the water tank 1 to generate convection in the oil-containing wastewater 4 that forms a downward flow at the center of rotation. The water tank 1 has a volume set in advance so as to maintain a residence time necessary for shearing the fats and oils contained in the fat and oil-containing waste water 4 with the stirring blade 5 and emulsifying and dispersing them in the fat and oil-containing waste water 4.

  Reference numeral 6 denotes a drive unit for rotating the stirring blade 5. In order to maintain the water tightness of the water tank 1, a magnet is provided in the driving unit 6 outside the water tank 1, and a magnetic material corresponding to the magnet of the driving unit 6 is provided in the stirring blade 5 so that the stirring blade 5 is moved by the driving unit 6. It is configured to be able to rotate. The stirring blade 5 is watertightly fixed to the bottom of the water tank 1. The rotating shaft (not shown) of the driving unit 6 is sealed with a mechanical seal or the like at the lower part of the water tank 1, and the stirring blade 5 is connected to the rotating shaft so that it can be directly driven by the driving unit 6. Also good. Further, the drive unit may be a submersible motor type and installed in the water tank 1, and is not particularly limited.

  In the present embodiment, the stirring blade 5 is a hollow stirring body and has a structure in which a negative pressure is generated in the hollow portion of the stirring blade 5 when the stirring blade 5 rotates, but it generates convection. Any shape is acceptable. Moreover, the baffle plate for preventing the oil-containing waste water 4 in the water tank 1 from rotating together covers the stirring blade 5.

  By configuring as described above, the following operation occurs. The oil-containing waste water 4 is introduced into the water tank 1 from the introduction pipe 2 to fill the water tank 1. The fat and oil-containing waste water 4 introduced by the introduction pipe 2 is the side wall of the water tank 1 due to the negative pressure generated by the stirring so that the water in the vicinity of the stirring blade 5 is moved away from the stirring blade 5 by the rotation of the stirring blade 5. It moves to 10 directions, and it becomes the upflow 11 along the side wall 10, and moves to the water surface vicinity. On the other hand, the oil-containing wastewater 4 moves in the direction of the side wall 10 in the central portion of the stirring blade 5, and a negative pressure is generated, so that the oil-containing wastewater 4 is sucked from above the rotation center portion. At this time, by reducing the depth of the fat-containing waste water 4 in the water tank 1 and increasing the number of revolutions of the stirring blade 5, the fat-containing waste water 4 near the water surface above the rotation center of the stirring blade 5 can also be obtained. Oils and fats floating on the water surface can be efficiently introduced to the stirring blade 5 and finely sheared to be emulsified. Thus, the particle size of the fats and oils of the fat-containing waste water 4 emulsified is suitable for biological treatment.

[Embodiment 2]
FIG. 2 shows a second embodiment of the present invention. In FIG. 2, reference numeral 7 denotes an air tube for introducing air from the outside into the water tank 1. One end is opened at the center of the stirring blade 5 and the other end is opened on the water surface of the oil-containing wastewater 4. Reference numeral 8 denotes air bubbles introduced into the oil-containing waste water 4 after the air introduced from the air pipe 7 is sheared by the stirring blade 5. Since other parts are the same as those of the first embodiment, description thereof is omitted.

  Next, the operation of this embodiment will be described. In the present embodiment, the stirring blade 5 rotated by the drive unit 6 generates a negative pressure by stirring so that the water in the vicinity of the stirring blade 5 is moved away from the stirring blade 5, and the flow of the oil-containing waste water 4 flows. Occurs, and a negative pressure is generated at the center of the stirring blade 5. Due to the negative pressure generated in the central portion of the stirring blade 5, the air pressure inside the air pipe 7 having one end opened to a position where the negative pressure is generated is lowered, and air is sent from the other end opened in the air of the air pipe 7. The air is sucked and air is discharged from the end opened at the center of the stirring blade 5. The discharged air reaches the stirring blade 5 together with the fat-and-oil containing waste water 4 and is finely sheared by the rotational shearing of the stirring blade 5 to form bubbles 8 and is sent into the fat-and-oil containing waste water 4.

  In this way, by mixing the bubbles 8 into the fat-containing wastewater 4 introduced into the stirring blade 5, the oil containing the fat near the side wall 10 of the water tank 1 by the rising action of the bubbles blown to the vicinity of the side wall 10 of the water tank 1. The momentum of the upward flow 11 of the waste water 4 will increase. Then, by forming a vigorous upward flow 11 near the side wall 10 of the water tank 1, the water surface above the central portion of the stirring blade 5 generates a strong downward flow due to negative pressure, and the oil-containing waste water 4 The fats and oils on the water surface are efficiently introduced to the stirring blade 5 and further finely dispersed under the influence of the rotational shearing force and emulsified in the fat and oil-containing waste water 4. As in the first embodiment, the fat and oil containing waste water 4 in the aquarium 1 is shallow and the number of revolutions of the stirring blade 5 is increased, so that the fat and oil content near the water surface above the center of rotation of the stirring blade 5 is contained. Even the waste water 4 can be drawn toward the stirring blade 5, and the fats and oils floating on the water surface can be efficiently introduced to the stirring blade 5 and finely sheared to be emulsified. Thus, the particle size of the fats and oils of the fat-containing waste water 4 emulsified is suitable for biological treatment.

[Embodiment 3]
FIG. 3 shows a third embodiment of the present invention. In FIG. 3, 9 is a draft tube provided in the oil-containing waste water 4 in the water tank 1. The draft tube 9 is provided vertically above the center of rotation of the stirring blade 5, the upper end of the draft tube 9 is disposed so as to open near the water surface of the oil-containing wastewater 4, and the lower end is the center of the stirring blade 5. It is provided so as to open at a position corresponding to the suction part of the part.

  As shown in FIG. 4, when the oil-containing waste water 4 stored in the water tank 1 reaches the upper limit water level, if it is pumped out to the lower limit water level using the pump 12 and the pipe 15, What is necessary is just to comprise so that the waste water 4 containing fats and oils may always flow in into a draft tube from the water surface by providing the float 14 in the opening part 13 vicinity using what can be moved up and down, such as an insertion type slide tube. In the present embodiment, the shape of the draft tube 9 is a plug-in type slide tube, but it is only necessary to follow the vertical movement of the water level, and a flexible hose or bellows hose may be used, which is particularly limited. is not. Since the rest is the same as that of the second embodiment, the description thereof is omitted.

  Next, the operation of this embodiment will be described. As in the second embodiment, the stirring blade 5 rotated by the drive unit 6 causes a negative pressure by stirring so that the water in the vicinity of the stirring blade 5 is moved away from the stirring blade 5, and the flow of the oil-containing waste water 4 occurs. A negative pressure is generated at the center of the stirring blade 5. Due to the negative pressure generated in the central portion of the stirring blade 5, the air pressure inside the air pipe 7 having one end opened to a position where the negative pressure is generated is lowered, and air is sent from the other end opened in the air of the air pipe 7. The air is sucked and air is discharged from the end opened at the center of the stirring blade 5. The discharged air reaches the stirring blade 5 together with the fat-and-oil containing waste water 4 and is finely sheared by the rotational shearing of the stirring blade 5 to form bubbles 8 and is sent into the fat-and-oil containing waste water 4.

  By mixing the bubbles 8 into the oil-containing wastewater 4 introduced into the stirring blade 5, the oil-containing wastewater 4 in the vicinity of the side wall 10 of the water tank 1 is raised by the rising action of the bubbles blown to the vicinity of the side wall 10 of the water tank 1. The momentum of the upward flow 11 will increase. Further, by installing the draft tube 9 at a position corresponding to the suction portion of the stirring blade 5, the upward flow 11 near the side wall 10 and the downward flow sucked into the stirring blade 5 are separated, so that the downward movement generated in the central portion The flow becomes more reliable, and the fats and oils staying in the vicinity of the side wall 10 can be almost eliminated.

  By providing the draft tube 9, the vigorous upward flow 11 that occurs in the vicinity of the side wall 10 can be reliably introduced into the central portion of the stirring blade 5, so that not only the fats and oils on the water surface but also the fat-containing waste water 4 The oil droplets floating on the water can be reliably and efficiently introduced to the stirring blade 5, finely dispersed under the influence of the rotational shear force, and emulsified in the oil-containing waste water 4. Thus, the particle size of the fats and oils of the fat-containing waste water 4 emulsified is suitable for biological treatment. In addition, the gap between the draft tube 9 and the water tank 1 is narrowed, and the fat-containing waste water 4 in the water tank 1 is more efficiently produced by using the vertically long water tank 1 so that a large amount of the oil-containing waste water 4 can be treated. Can shear. Furthermore, by increasing the number of revolutions of the stirring blade 5, the amount of the oil-containing wastewater 4 introduced into the draft tube 9 per unit time increases, and the flow rate passing through the stirring blade 5 increases, so that the amount of time can be increased in a short time. Shears small.

Next, an emulsification / dispersion test of fats and oils was performed using each device of the first embodiment (Example 1 (Reference Example) ) to the third embodiment (Example 3) of the present invention. The results are shown below. As a comparative example, a test was performed using the apparatus described in Patent Document 1. The schematic diagram of the fats and oils dispersion apparatus of a comparative example is shown in FIG. This was carried out using tap oil as raw water and wastewater containing simulated fats and oils mixed with salad oil often used in the food industry. The particle size distribution of dispersed particles at that time was measured, and the median diameter was calculated from the particle size distribution. A measuring apparatus and a test method are shown below. The median diameter here refers to a particle diameter corresponding to 50% cumulative in the particle diameter distribution.

[Measurement device for oil droplet size distribution and median size]
HORIBA, Ltd .: Laser diffraction / scattering particle size distribution analyzer (LA-910W)
Measurement principle: Light source based on Mie scattering theory: Combined use of He-Ne laser and tungsten lamp

〔Test method〕
Twelve liters of tap water was put into a water tank, 20 cc of salad oil (commercial product) was added thereto, and after operating for a predetermined time, a simulated oil / fat-containing wastewater was obtained and measured with the above-described apparatus.

  Table 1 shows the median diameter of dispersed particles when salad oil was dispersed for 5 minutes in Examples 1 to 3. FIG. 5 is a graph showing the dispersion distribution of particles. In this test, the salad oil of the comparative example was not emulsified at all, and a white turbidity phenomenon indicating that the tap water was also emulsified was not obtained. In Example 1 and Example 2, although the oil was dispersed in tap water, the median diameter was about 43 μm and about 46 μm. On the other hand, in Example 3, the median diameter was about 24 μm, which was about half the particle diameter. Further, as shown in FIG. 5, in Example 3, 77.3% was distributed in a particle diameter of 40 μm or less.

  Table 2 shows the median diameter of the dispersed particles when salad oil was dispersed for 10 minutes in Examples 1 to 3. FIG. 6 is a graph showing the dispersion distribution of particles. In this test, the salad oil of the comparative example was not emulsified at all, and the cloudiness phenomenon indicating that the tap water was also emulsified was not obtained. In Example 1, although the oil was dispersed in the tap water, the median diameter was about 44 μm, which was not much different from the case of the treatment for 5 minutes, but in Example 2, it was further reduced to about 28 μm. On the other hand, in Example 3, the median diameter was about 18 μm and was further dispersed. As shown in FIG. 6, in Example 3, 79.8% was distributed in a particle diameter of 40 μm or less.

  Table 3 shows the median diameter of the dispersed particles when salad oil is dispersed for 30 minutes in Example 1, Example 3, and Comparative Example. FIG. 7 is a graph showing the dispersion distribution of particles. In the comparative example, the oil was not finely dispersed in the tap water and was not emulsified, but it was intentionally measured. As shown in Table 3, in Example 3, the median diameter was very finely dispersed at 13.55 μm, and in Example 1, the result was not significantly different from the case of treatment for 10 minutes. Furthermore, in the comparative example, the result was that measurement was impossible. Further, as shown in FIG. 7, in Example 3, the result that 71.3% was distributed in a particle diameter of 20 μm or less was obtained.

  By using the present invention, waste water treatment of substances that are difficult to disperse in water can be performed, which can greatly contribute to prevention of environmental pollution. Moreover, it can be used not only for fat-and-oil-containing wastewater but also as a device for dispersing gel-like substances in liquids in the food processing industry. Further, it can be used as a reaction device for gas and liquid.

It is the schematic diagram which showed 1st Embodiment which is reference embodiment of this invention. It is the schematic diagram which showed the 2nd Embodiment of this invention. It is the schematic diagram which showed the 3rd Embodiment of this invention. It is the schematic diagram which showed another form of the draft tube in the 3rd Embodiment of this invention. It is a graph showing the particle diameter distribution when processing for 5 minutes in an Example. It is a graph showing the particle size distribution when processing for 10 minutes in an Example. It is a graph showing the particle diameter distribution when processing for 30 minutes in an Example. It is the schematic diagram showing the testing apparatus of the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water tank 2 Introducing pipe 3 Transfer pipe 4 Oil and fat containing waste water 5 Stirring blade 6 Drive part 7 Air pipe 8 Bubble 9 Draft tube 10 Side wall 11 Upflow 12 Pump 13 Opening part 14 Float 15 Piping 100 Water tank 101 Pipe body 102 Air pipe 103 Air Blowing means 104 Blower

Claims (4)

By rotating the stirring blade at oil-containing waste water, see write winding fats and oils on the water surface causes a convection having a downward flow in the oil-containing waste water by the rotation of the stirring 拌羽, in addition the stirring blade of the central portion One end is opened and the other end is opened on the surface of the oil-containing wastewater, and air is introduced into the oil-containing wastewater from the outside by a negative pressure generated at the rotation center of the stirring blade through an air pipe for introducing air from the outside. A method for dispersing fats and oils in oil-containing wastewater, comprising drawing air bubbles into the oil-containing wastewater and dispersing the fats and oils in the fat-containing wastewater. A draft tube having a water tub and a transfer tube is provided for transferring the waste water and the introduction pipe were dispersed to introduce oil containing waste water, an opening in the vertical provided in the water tank, under direction of the draft tube A downflow generator that generates a downflow by rotation of the provided stirring blade, and air is introduced from the outside where one end is opened at the center of the stirring blade and the other end is opened on the surface of the oil-containing wastewater. An apparatus for dispersing fats and oils in oil-containing wastewater, characterized by having an air pipe . 3. The oil-containing wastewater according to claim 2 , wherein the downflow generator is a fine bubble generator that generates a fine bubble while generating air under pressure by generating a negative pressure at a rotation center of a stirring blade. Oil and fat dispersion device inside. 4. The oil and fat dispersion device for oil and fat-containing wastewater according to claim 2 or 3 , wherein the suction side opening of the draft tube is configured to follow the fluctuation of the water level in the water tank.

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