JPH0314517B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for coagulating flotation of wastewater that utilizes both dispersed bubbles and precipitated bubbles and further utilizes an organic polymer flocculant, and a coagulation flotation device used in the method. be. The present invention can be applied not only to general wastewater treatment but also to coagulation flotation separation treatment of various liquids, such as sludge concentration treatment. Furthermore, the gas used in the present invention does not necessarily have to be air; for example, nitrogen-rich air (the gas remaining after oxygen is selectively extracted from air) can also be used. [Prior art] Generally used flotation separation treatment methods and devices for wastewater include (a) pressurized flotation separation methods and devices that utilize precipitated bubbles, and (b) conventional methods and devices that primarily utilize dispersed bubbles. This is a pressure flotation separation method and device. In addition, electrolytic flotation separation methods and devices, flotation separation methods and devices using aeration tubes, etc. are known, but these methods and
The device is limited to special uses. (a) Pressure flotation separation method/equipment Water and air are retained in a pressure vessel, the air is dissolved in water under pressure while exhausting excess air, and this dissolved liquid is extracted to make waste water from the flotation tank. Introduce it inside. Dissolved air becomes bubbles under atmospheric pressure, and impurities (components to be removed) in wastewater are removed.
Since the impurities precipitate and adhere to the aggregates, the impurities are floated and separated by the buoyancy of the precipitated bubbles. That is, according to this method, impurities in wastewater are separated mainly by the adhesion action of precipitated bubbles. pressure·
Although it depends on conditions such as temperature, in general, according to this method, the amount of precipitated bubbles is 2 times the normal volume of water.
~3%. Furthermore, according to this method, bubbles are deposited in both aggregated impurities and non-agglomerated impurities, so separation accuracy is high. (b) Atmospheric pressure flotation separation method and device: Introducing air into water and passing it through a static mixer to create dispersed air bubbles in the water, and mixing the water containing these dispersed air bubbles with wastewater.
Furthermore, impurities are aggregated by adding an organic polymer flocculant. At this time, the dispersed bubbles present in the wastewater are trapped in the coagulating impurities, and the impurities are floated and separated by the buoyancy of the dispersed bubbles. That is, according to this method,
Impurities in wastewater are separated primarily by the entrainment effect of dispersion bubbles. Generally, according to this method, the amount of dispersed bubbles is 10 to 30% of the normal volume of water, and since the amount of bubbles is larger than that in the pressure flotation method, the flotation rate is faster. Furthermore, the apparatus of this method is relatively smaller and simpler than the apparatus of the previous method. [Problems to be Solved by the Invention] According to the pressure flotation method, there are problems in that the flotation speed is slow because the amount of bubbles is relatively small, and a large flotation tank is required. In addition, a large pressurized tank and a device to control the level within the tank are required, and the piping becomes complicated, making the entire device larger, increasing the installation cost, and handling the operation and maintenance of the device. The problem is that it becomes complicated. According to the normal pressure flotation separation method, impurities that have already been aggregated by the organic polymer flocculant and impurities that do not (or are difficult to aggregate) by the organic polymer flocculant
Regarding impurities, there was a problem in that as a result of the entrapment of dispersed bubbles being difficult to be carried out, the separation accuracy of impurities was inferior to that of the pressure flotation separation method. Furthermore, as long as dispersed bubbles are created by mechanical operations, it is inevitable that large diameter bubbles will be generated in the liquid. Such coarse bubbles (e.g. approx.
It is thought to be 100 μm or more. ), the agitation effect is stronger than the adhesion effect or the enveloping effect, and is thought to be one of the factors that deteriorates the separation accuracy. [Purpose of the Invention] Based on the advantages and disadvantages of the conventional flotation separation methods and devices, the inventor of the present application has conducted various tests on each of these devices, and has found the following (a) to (c). We have come to confirm the facts shown below. (a) When flotation separation is performed using both precipitated bubbles and dispersed bubbles, the separation speed tends to increase and the separation accuracy also tends to increase. (b) The effectiveness of both bubbles differs depending on the type of wastewater and treatment target level. For example, for oil-containing wastewater from an oil refinery, it is better to increase the number of precipitated bubbles, and for wastewater from a cafeteria, it is better to increase the number of dispersed bubbles to obtain better results. (c) Removal of coarse bubbles in the dispersed bubbles improves separation accuracy. Therefore, in the present invention, dispersed bubbles and precipitated bubbles are generated in wastewater in arbitrary amounts and ratios, and an organic polymer flocculant is added to the wastewater to coagulate the components to be removed. The purpose is to provide a coagulation flotation separation method that can effectively treat various wastewaters by
Furthermore, it is an object of the present invention to provide a coagulation flotation separation device that is effective for use in the method. [Means for Solving the Problems] The coagulation flotation separation method of the present invention allows fine dispersed air bubbles and precipitated air bubbles to be mixed in arbitrary amounts in wastewater in a flotation tank.
At the same time, an organic polymer flocculant is added to the wastewater to coagulate the target component to be removed, and the bubbles are attached to or included in the flocculated target component to be removed, so that the target component to be removed is floated and separated. It is characterized by Further, the coagulation flotation separation device of the present invention includes a flotation separation tank for treating wastewater;
A bubble generator that generates fine dispersed bubbles and precipitated bubbles in arbitrary amounts and proportions in the wastewater in the flotation separation tank, and a chemical agent for adding an organic polymer flocculant to the wastewater in the flotation separation tank. It is characterized by having an addition port. [Operation] The bubble generator generates fine dispersed bubbles and precipitated bubbles in the wastewater in the flotation separation tank in any amount and ratio that matches the properties of the wastewater. Then, an organic polymer flocculant is added to the wastewater through the chemical addition port, and the components to be removed are flocculated in the flotation tank where air bubbles are generated. Since the bubbles are included in the aggregated components to be removed or are deposited and attached to the surface of the aggregated components to be removed, the aggregated components to be removed are floated and separated by the buoyancy of the bubbles. [Example] An example of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic structural diagram showing a coagulation flotation separation apparatus according to this embodiment. In the figure, reference numeral 1 denotes a two-tank reaction tank to which raw wastewater is supplied, and the reaction tank 1 is provided with a chemical injection device 2, an agitator 3, a reaction control sensor 4, and the like. The raw wastewater supplied to the reaction tank 1 is subjected to pre-treatment such as chemical injection by these devices, and is then sent from the inlet 5 of the wastewater W (water to be treated) to the pipe P.
1 and sent to the auxiliary tank 6a of the flotation tank 6. Further, a chemical addition port 7 is provided in the middle of the pipe P1 via a valve V1, so that an organic polymer flocculant can be added to the wastewater W sent into the flotation separation tank 6.
A rotary vane type scum skimmer 8 is provided at the top of the flotation separation tank 6, and the wastewater W stored in the tank is
The impurities that have risen to the surface of the water can be scraped out of the tank. Also flotation separation tank 6
An outlet 9 for treated water is connected and communicated with the lower part of the pipe P2 through a pipe P2. Further, a pipe P3 is connected to the bottom of the funnel-shaped flotation separation tank 6, and the pipe P3 is connected to a suction pipe 11 of a pump 10 as a bubble generator via a valve V2. . Therefore, the treated water in the flotation tank 6 is supplied to the pump 10. Next, the pump 10 is provided to generate air bubbles in the waste water W in the flotation tank 6, and disperses and dissolves air in the treated water drawn from the flotation tank 6. The connection structure is such that these fluids can be sent to the auxiliary tank 6a of the flotation separation tank 6 again. This pump 10 may be configured by modifying a normal centrifugal pump (for example, a single-side suction horizontal non-self-contained pump with a simple, inexpensive, and easy-to-handle structure); however, in general, in a normal centrifugal pump, When the proportion of gas in the fluid increases,
In addition to causing vibrations, abnormal noises, and abnormal wear of the rotating blades, there may be other inconveniences such as the inability to discharge fluid or the fluid being discharged intermittently. The inventors of the present invention believe that the cause of such inconvenience lies in the shape of the fluid passage in the impeller section, and further confirmed that the cause is that the cross-sectional area of the fluid passage is larger on the outlet side than on the inlet side. Therefore, in this embodiment, as will be described later, a pump with a structure that can pump more gas together with liquid is used.
This makes the overall effectiveness of the device even higher. Reference numeral 12 shown in FIG. 2 is an impeller body composed of a main plate 14 having a boss 14a to which a drive shaft 13 is attached, and a plurality of blades 15 provided on one side of the main plate 14. . The blades 15 of the impeller body 12 have holes 16a in the center.
A disk-shaped side plate 16 having a shape formed thereon is fixed thereto, and constitutes an impeller portion 17. As shown in FIG. 3a, the blades 15 have a claw-shaped cross-sectional shape curved into an arc, and each blade 15, the side surface of the main plate 14, and the inner surface of the side plate 16 form a plurality of blades. A fluid passageway 18 is defined. Unlike the fluid passage in a normal centrifugal pump, this fluid passage 18
is an elliptical inlet 19 as shown in FIG. 3b.
The side cross-sectional area is large, and the cross-sectional area on the elliptical outlet 20 side is smaller, and its wall surface has a smooth shape with no corners. However, depending on the manufacturing cost and other considerations, the cross-sectional shape of the fluid passage 18 may be square, with corners. In addition, both cross-sectional areas are determined by the fluid pressure at the outlet 20 and the fluid pressure at the outlet 20 so that the apparent flow rate of the fluid in the fluid passage 18 (the value obtained by dividing the apparent volume of fluid flowing within a certain period of time by that time) is constant. It is set based on the mixing ratio of gas and liquid. For example, when trying to mix and transfer 6 m ³ /h of water and 2 m ³ /h of air, the fluid pressure at the outlet 20 is 5 Kgf/cm ²
Then, the volume of the gas will be compressed to about 1/5, so
Cross-sectional area A on the inlet 19 side and cross-sectional area on the outlet 20 side
A' can be determined by the following equation. 6+2/A=6+0.4/A' Next, the casing portion in which the impeller portion 17 is housed will be described. The outer partition wall 21 of the casing portion has a substantially truncated conical shape, and a disk-shaped flange 22 is fixed to the small diameter left end surface. A liquid supply hole 22a is formed in the center of the flange 22, and the supply hole 22a communicates with the suction pipe 11 attached to the center of the inner surface of the flange 22.
The suction tube 11 is installed horizontally in the center of the outer partition wall 21, and a circular wall plate 23 is provided at the open end opposite to the supply hole 22a. The impeller section 17 is rotatably mounted on the wall plate 23 and the open end of the suction tube 11. A lid member 24 is fitted and fixed to the large-diameter opening end of the outer partition wall 21, and the internal space of the outer partition wall 21 is converted into a second spiral chamber S.
It is divided as 2. Further, the left end surface of the lid member 24 contacts the outer peripheral edge of the wall plate 23 inside the outer partition wall 21 and rotatably holds the impeller portion 17 between it and the wall plate 23. Figures 2 and 3
As shown in FIG. A spiral space is constructed. The first vortex chamber S1 opens and communicates with the second vortex chamber S2, so that the fluid urged in the first vortex chamber S1 flows into the second vortex chamber S2 along the tangential direction. It is composed of A discharge port 25 is provided at the left end of the second volute chamber S2, which has a smaller inner diameter, in a tangential direction to the cylindrical outer partition wall 21. A portion of the fluid that has moved to the left end while rotating is configured to be discharged tangentially to the outside. Further, an extraction pipe 26 is provided through the outer partition wall 21 . The open end of the extraction pipe 26 is provided at a position near the suction pipe 11 provided at the center of the second swirl chamber S2, that is, at the center of rotational movement of the fluid, and away from the discharge port 25. It is configured so that some of the fluid that has collected at that location can be extracted from the room. A small-diameter supply pipe 27 is coaxially provided inside the suction pipe 11, and the supply pipe 27 penetrates the peripheral wall of the suction pipe 11 and the flange 22 to communicate with the outside. The pump of this embodiment has the above-described configuration, but when expanded, the space S2' in the part of the second spiral chamber S2 where the outer partition wall 21 is parallel to the central axis C becomes the seventh volume.
It has a shape as shown in figure a. That is, since the axial dimension A is constant, the fluid is pushed out to a large extent in the direction of the axis C in this space S2', as shown by the arrow in FIG. 7b, and the centrifugal force tends to be reduced. Therefore, as shown in FIGS. 5, 6, and 8, a pump in which the shape of this space S2' is particularly improved may be used in this embodiment. That is, the axial length A of the space S2' is maximum at the 0° position in the cross-sectional view shown in FIG. 6, and gradually decreases along the rotational direction until it reaches the maximum length at the 180° position. almost half of
Make it 0 at the 360° position. This space S
FIG. 8a shows an exploded perspective view of 2', in which both the axial length A and the radial length become shorter along the rotational direction. For this reason, Fig. 8b
As shown by the arrow in , the fluid is gradually pushed out in the direction of axis C while rotating under the influence of centrifugal force. Therefore, if such a pump is used, a larger centrifugal force can be applied to the fluid in the second volute chamber S2, so that the fluid in the second vortex chamber S2 can be stirred more effectively.
Note that the pump shown in Fig. 5 does not show the extraction pipe 26 and various valves V3, V4, etc. as shown in Fig. 2, but if this pump is used as an example, the pump shown in Fig. 2 and the like are not shown. Needless to say, they have a similar configuration. Furthermore, as shown in FIG.
may be provided at two locations 180° apart from each other in the direction of rotation. The shape of each part of the spiral chamber S2 near the two outlets EX is formed as shown in FIG. 8a. That is, at the 0° position in FIG. 9, the axial and radial dimensions of the part of the spiral chamber S2 near one outlet EX are maximum, and decrease along the rotational direction to 180°. It becomes 0 at the position. For the part of the vortex chamber S2 close to the other outlet EX, the axial and radial dimensions are maximum at 180° and decrease along the rotational direction to 0 at 360°. There is. In this way, even if the outer diameter of the second swirl chamber S2 is made small, the fluid can be efficiently stirred. In the improved examples or other structural examples of the pump described above with reference to FIGS. 5 to 9, the shape of the fluid passage in the impeller portion is formed similarly to that of the pump shown in FIG. 3a. That is, as shown in FIG. 3b, the cross-sectional area on the inlet 19 side of the circular shape is larger, and the cross-sectional area on the outlet 20 side of the circular shape is smaller, and the wall portion is smooth with no corners. However, depending on manufacturing conditions, corners may be provided. Next, an injector 28 is provided outside the outer partition wall 21 to suck in gas using the kinetic energy of the passing fluid. As shown in FIG. 4, the injector 28 is a pump-shaped device that has a passage in the center through which fluid passes, and has a tapered shape in which the inner diameter is narrowed from the inlet 29 to the center where the throttle hole 30 is located. It is formed in a tapered shape in which the inner diameter increases from the central part to the outlet 31. A suction port 32 communicating with the aperture hole 30 is formed on the outer circumferential surface of the central portion.
The structure is such that gas is sucked in from the suction port 32 by the kinetic energy of the fluid passing from the inflow port 29 toward the outflow port 31 . Also, a check valve 33 is provided inside the suction port 32 so that the fluid flowing from the inflow port 29 to the outflow port 31 is directed to the suction port 32.
It is designed to prevent it from being discharged to the outside. In addition, a disk-shaped twisted blade 34 is rotatably provided at the inlet 29 of the injector 28 to stabilize the gas suction force and to effectively atomize the gas sucked into the injector 28. It's summery. In addition, instead of such a disk-shaped twisting blade 34, a propeller-shaped blade with less pressure loss may be provided. Next, the inlet port 29 of the injector 28 and the outlet pipe 26 are connected by a pipe via a valve V3, and a pressure gauge 35 is provided in the middle of the pipe. The outlet 31 of the injector 28 and the supply pipe 27 are connected by piping. The suction port 32 of the injector 28 is opened to gas at a predetermined pressure via a valve V4 and a flow meter 36. Further, as described above, the suction pipe 1 of the pump 10
1 is connected to the bottom of the flotation separation tank 6,
The impeller section 17 is supplied with treated water in the flotation separation tank 6. Further, the drive shaft 13 of the impeller portion 17 is connected to the lid member 24.
It passes through and is supported by a bearing 37, and its end is operatively connected to the output shaft of the motor M by a flange joint 38. Next, a storage tank 39 is provided next to the flotation separation tank 6 to store the components to be removed that have been scraped off by the scum skimmer 8. This storage tank 3
9 is provided with a drug inlet, and arrow A1
As shown in the figure, it is now possible to add chemicals to the sludge in the tank. Also, this storage tank 39 has an agitator 4.
0 is also provided. Next, a dehydrator 41 is installed next to the storage tank 39. This dehydrator 41 has an endless material 42 that is wound around a plurality of rollers 44 and 45 and driven to circulate. The endless material 42 is sandwiched between a rotatably installed press drum 43 and a plurality of (five in the illustrated example) rollers 44 coaxially provided along the circumferential surface of the press drum 43. It's becoming like that. The sludge treated with chemicals in the storage tank 39 is carried on the endless material 42 and is pressed against the endless material 42 between the pressing drum 43 and the roller 44 . The water contained in the sludge is separated through the endless material 42 and placed in the lower saucer 4.
The sludge stored in the storage tank 6 and dehydrated into a cake shape is scraped off by a scraper 47 and falls onto the loading platform of a transport vehicle 48. Next, an embodiment of a method for coagulating flotation and separation of wastewater using the apparatus configured as described above will be described. A pump 10 is driven by a motor M, and air and water in the flotation separation tank 6 are sucked into the pump 10.
The liquid and gas sucked into the impeller section 17 are pressurized while moving through the fluid passage 18 having a smooth shape. The fluid passage 18 of the impeller part 17 in the pump 10 of this embodiment has a large cross-sectional area on the inlet 19 side through which the uncompressed fluid passes, and a small cross-sectional area on the outlet 20 side through which the compressed fluid passes. . Therefore, when a liquid and a gas, which is a compressible fluid, are pumped together, from the inlet 19 in the fluid passage 18 to the outlet 2
0, the apparent flow velocity of the fluid (the value obtained by dividing the apparent volume of fluid flowing within a certain period of time) becomes constant, so there are no regions with different pressures within the fluid passage 18, and No inconveniences such as generation of harmful vortices occur. In particular, in this embodiment, the wall surface of the fluid passage 18 has a smooth shape with no corners, so the resistance between the wall surface and the fluid is uniform in all parts, which may cause wear of the wall surface. There is also no fear that fluid vortices will occur in specific parts. In this way, the gas and liquid sucked into the impeller section 17 are smoothly transferred at a constant flow rate within the smooth-shaped fluid passage 18 without generating a vortex, so that a considerable amount of gas can be pumped together with the liquid. Even if the pump 10 is in operation, no disturbances such as abnormal noise or vibration will occur, and
Moreover, the wall surface of the fluid passage 18 will not be abnormally worn. Then, in the impeller section 17, the sucked gas is pressurized and pulverized into fine pieces, and dispersed and mixed into the liquid. This fluid flows into the first swirl chamber S1 and is stirred, and some of the gases dissolve into the liquid. This fluid then exits the first volute chamber S1 tangentially and flows into the second volute chamber S2. In the vortex chamber S2, the liquid and the finely dispersed gas rotate violently, and the dissolution of the gas further progresses due to stirring and retention. Inside the second swirl chamber S2,
A large amount of fluid with a relatively low specific gravity, that is, a liquid containing a large amount of undissolved bubble-like gas, gathers in the center of the second swirl chamber S2 due to centrifugal force. Additionally, gases that have become difficult to dissolve due to their association and increase in volume, and gases that are coarse from the beginning, also gather in the center. That is, in the second swirl chamber S2, centrifugal force causes gas-liquid separation and gas-gas separation (separation of coarse and fine bubbles).
are being done at the same time. On the other hand, a fluid with a relatively large specific gravity, that is, a liquid containing a certain amount of fine dispersed bubbles and dissolved gas (dissolved liquid), rotates and moves to the left end of the second swirl chamber S2, and passes through the discharge port. 25 to valve V5. In this case, since the amount of solution coming out of the discharge port 25 is kept constant by appropriately adjusting the opening degree of the valve V5, the pressure inside the second swirl chamber S2 is kept constant. There is. Then, the solution containing fine dispersed bubbles that has passed through the valve V5 joins the pretreated wastewater to which the organic polymer flocculant has been added from the drug addition port 7, and flows into the auxiliary tank 6a of the flotation tank 6. sent. Since the flotation separation tank 6 is open to atmospheric pressure, the gas dissolved in the liquid becomes precipitated bubbles in the wastewater under atmospheric pressure, adheres to impurities in the wastewater, and floats and separates them. On the other hand, since dispersed air bubbles are trapped in the impurities aggregated by the organic polymer flocculant, these impurities are also floated and separated. As described above, according to the method of this embodiment, the adhering action of the precipitated bubbles and the enclosing action of the dispersed bubbles have a synergistic effect, and impurities in wastewater are efficiently floated and separated in a short time with high accuracy. Then, the floating impurities are scraped out of the tank by the scum skimmer 8, and then the moisture is separated by the dehydrator 41, and the impurities are turned into a cake and transported to the outside. The treated water passes through the pipe P2 and is discharged from the outlet 49 to a predetermined position outside. Next, the water containing more undissolved air bubbles is
It is extracted from the extraction pipe 26 and supplied to the inflow port 29 of the injector 28, and flows through the injector 28 to the outlet port 3.
Passing towards 1. At this time, air is sucked into the injector 28 from the suction port 32 by the kinetic energy of the passing fluid. The suction force of air is determined by the magnitude of the kinetic energy of the fluid passing through it,
That is, it varies depending on the amount of bubbles contained in the fluid. For example, if the fluid extracted from the extraction tube 26 contains many bubbles, the kinetic energy of the fluid is small, so
The amount of air sucked into the injector 28 is reduced. Conversely, if the fluid contains almost no air,
A large amount of air is sucked into the injector 28 by a strong suction force corresponding to the kinetic energy. In this way, in the pump 10 of this embodiment, the amount of gas suction is self-controlled. The air sucked in by the injector 28 is dispersed in the liquid and is atomized in the injector 28 together with the undissolved gas sent from the second swirl chamber S2, and then dispersed and mixed in the liquid. Ru. Further, in this embodiment, since the injector 28 is provided with the twisted blades 34, the gas suction state is stable. Next, the fluid that has passed through the injector 28 joins the water sent from the flotation tank 6, is sucked into the suction pipe 11 of the pump 10, and is sent to the impeller section 17 again. As described above, the liquid sent from the pump 10 to the flotation tank 6 contains a predetermined amount of fine dispersed air bubbles, and also has dissolved air that becomes precipitated air bubbles under atmospheric pressure. By appropriately adjusting the amount and proportion of dispersed bubbles and precipitated bubbles in the wastewater W in the flotation separation tank 6 according to the properties of the wastewater W to be treated, highly accurate and efficient coagulation flotation separation treatment can be performed in various ways. This can be done for waste liquid. In the embodiment described above, the amount of dispersed bubbles can be increased or decreased by adjusting the amount of air sucked into the injector 28 by operating the valve V4. Furthermore, the saturated dissolution amount of air in water is determined by the pressure, and the residence time until reaching saturation in the second volute chamber S2 is determined by the device system. The capacity of the second swirl chamber S2 may be determined so that the discharge amount discharged into the second swirl chamber S2 can remain in the second swirl chamber S2 for the residence time.
Since the discharge pressure of the pump 10 can be lowered by increasing the amount of circulating water, the amount of precipitated bubbles can also be adjusted. In this embodiment, an appropriate amount of water is extracted from the flotation tank 6 and supplied to the pump 10, and a portion of the fluid containing more undissolved gas is transferred to the second swirl chamber S2 of the pump 10. The gas is separated by centrifugal force, and while being circulated within the system, the injector 28 self-controls the intake air amount, thereby efficiently dispersing and dissolving the gas in the liquid. In other words, in the device of this embodiment, since the fluid is circulated, there are many chances of contact between gas and liquid, and since the gas is repeatedly atomized in various places, the contact area of gas and liquid is large, so the air has a large contact area with water. Dispersion and dissolution are extremely efficient. Then, the solution containing dispersed bubbles is transferred to the second vortex chamber S of the pump 10.
2 and returned to the flotation tank 6, and the fine dispersed bubbles and precipitated bubbles are combined with an organic polymer flocculant to carry out coagulation and flotation treatment of wastewater with high precision and in a short time. Next, the results of testing the flotation and separation device will be explained using a specific example. Discharge amount 0.10m ³ /
An impeller part 17 having a fluid passage 18 as described above in a water single suction centrifugal pump with a total head of 39 m.
Install. The substantially truncated conical outer partition wall 21 constituting the second spiral chamber S2 has an inner diameter of φ300×φ250 and a length of about 250 mm. The injector 28 is
The inner diameter of the entrance and exit part was about 10 mm, the total length was about 50 mm, and the inner diameter of the throttle hole 30 was about 3 mm. The self-suction air amount of this injector 28 is
The inflow pressure is 4.0Kgf/cm ² and the inflow rate is 1/min.
It has been experimentally confirmed that it is 10N/min when . Now, the waste liquid to be treated here is hotel chusuke waste liquid (waste liquid generated when chusuke is crushed and dehydrated).
The test was conducted using air as the gas and varying the amount of suction air. The results are shown in Table 1 as Example (1). Also, Example (2) shown in Table 1
The data in ~(6) were obtained by setting the waste water to zero and adjusting the pump flow rate, discharge pressure, etc. by operating each valve. For comparison, the results obtained using the conventional apparatus under almost the same conditions are shown in Tables 2 and 3 together with Example (1). Comparative examples in Tables 2 and 3
(A) is an apparatus that mainly uses dispersed bubbles as explained in the [Prior Art] section, and comparative example (B) is an apparatus that mainly uses precipitated bubbles as explained in the [Prior Art] section. be.

【table】

【table】

[Table] As shown in Examples (2) to (6) in Table 1, according to the apparatus and method of this example, dispersed bubbles and precipitated bubbles can be obtained in arbitrary amounts and ratios. Therefore, it is possible to carry out coagulation flotation separation treatment that corresponds to the properties of the wastewater to be treated. As can be seen from Table 3,
In this example, the residence time of the fluid in the flotation tank was 12 minutes, which is the same as in Comparative Example (A).
Judging from the analytical values of the treated water shown in , the coagulation flotation separation accuracy is higher in Example (1) than in Comparative Example (A). Comparative example
(B) requires considerably longer residence time than Example (1), but from the analytical values, the agglomeration flotation separation accuracy is better than that of Example (1).
Considerably inferior to (1). As described above, according to this example, the coagulation flotation separation rate is considerably high, and the accuracy is very excellent, and it has been confirmed that effective coagulation flotation separation treatment can be performed efficiently depending on the type of waste liquid. Ta. In the embodiment described above, the treated water extracted from the flotation tank 6 is led to the pump 10, and the water is returned to the flotation tank 6 after air bubbles are dispersed and dissolved therein. The connection relationship between the pump 10 as a bubble generator and the flotation separation tank 6 is not limited to the above configuration, for example, as shown in FIG. 1b,
A pump 10 is provided between the reaction tank 1 and the flotation separation tank 6, and the entire amount of pretreated wastewater sent from the reaction tank 1 is passed through the pump 10 and pressurized together with air.
Alternatively, it may be fed into the flotation separation tank 6. In addition to the pipe configuration shown in FIG. _1b , as shown in FIG. Approximately half of the pretreated wastewater is pressurized together with air in a pump 10 and sent to a flotation separation tank 6.
You may also send it to Further, in the above embodiment, the chemical addition port 7 was provided in the center of the pipe P1 that communicates the reaction tank 1 and the flotation tank 6, but the discharge port 25 of the pump 10 and the flotation tank 6
A drug addition port may be provided in the middle of the pipe that communicates with the drug. [Effects of the Invention] According to the coagulation flotation separation method and apparatus according to the present invention, fine dispersed bubbles and precipitated bubbles can be generated in arbitrary amounts and proportions in the waste liquid in the flotation tank, and an organic polymer flocculant can be added to the waste liquid in the flotation tank. Since the components to be removed can be agglomerated using a compact device, the effect is that accurate coagulation flotation separation can be performed efficiently on various types of waste liquids using a small and simple device. be.

[Brief explanation of the drawing]

Figure 1a is a schematic block diagram showing one embodiment of the device according to the present invention, and Figures 1b and c show another embodiment of the connection structure between the pump, flotation tank, and reaction tank in the same embodiment. 2 is a sectional view of the pump in the same embodiment; FIG. 3a is a sectional view taken along the - cutting line in FIG. 2; FIG. The figures are a sectional view of the injector in the embodiment, FIG. 5 is a sectional view showing an improved example of the pump in the embodiment, and FIG.
The figure is a cross-sectional view taken along the - section line in Figure 5, and Figure 7.
Figure 8a is an exploded perspective view of the space S2' of the pump according to the embodiment, Figure b is a diagram showing the movement of fluid in the space S2' of the pump, and Figure 8a is the space S2 of the pump according to the improved example. FIG. 9 is a perspective view showing the movement of fluid in the space S2' of the pump, and FIG. 9 is a sectional view showing another structural example of the pump in the embodiment. 6...flotation separation tank, 7...drug addition port, 10...
... Pump as a bubble generator, 28... Injector, W... Waste water.

Claims (1)

[Claims] 1. Fine dispersed bubbles and precipitated bubbles are generated in arbitrary amounts and proportions in wastewater in a flotation separation tank, and an organic polymer flocculant is added to the wastewater to aggregate the components to be removed. A method for coagulation and flotation of wastewater, characterized in that the agglomerated components to be removed are floated and separated by adhering to or including the air bubbles in the components to be removed. 2. A flotation separation tank for treating wastewater; a bubble generator that generates fine dispersed bubbles and precipitated bubbles in arbitrary amounts and ratios in the wastewater in the flotation separation tank;
A coagulation flotation separation device comprising: a chemical addition port for adding an organic polymer flocculant to wastewater in the flotation tank.