JP4142504B2 - High speed levitation separation method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-speed floating separation method and apparatus based on a new principle of water to be treated (hereinafter, also referred to as “raw water”) containing substances to be removed such as river water, lake water, sewage, and industrial wastewater. .
[0002]
[Prior art]
Conventionally, a method is known in which pressurized dissolved air-containing water or fine bubbles are blown into raw water, and suspended particles are attached to the bubbles to float and separate. (For example, refer nonpatent literature 1).
[0003]
[Non-Patent Document 1]
“Water Treatment Engineering”, Gihodo, 1990, p. 87-99
[0004]
[Problems to be solved by the invention]
However, such a conventional levitation separation method has a drawback that the levitation separation speed is as low as about 100 to 200 mm / min, and additional facilities such as an air compressor and an air melting facility are required.
[0005]
The present invention has been made under such circumstances, solves the problems of the conventional flotation separation technology, and can float and separate suspended particles and the like in various raw waters at a very high speed by a simple operation. It is an object of the present invention to provide a high-speed levitation separation method and apparatus that do not require an air compressor or an air melting facility.
[0006]
[Means for Solving the Problems]
The present invention has solved the above-described problems by the following means.
(1) At least floating particles and an organic polymer flocculant are added to the water to be treated containing the substance to be removed and stirred to attach the flocs of the substance to be removed to the floating particles. The floating separation water obtained by removing the flocculated flocs by the floating separation is allowed to flow down to a rotary net having a larger opening than the particle size of the floating particles provided at the bottom of the floating separation portion. The treated water is taken out from below the net, and the solid matter captured by the net is sucked and removed by a pipe-shaped suction water flow generating member having a suction slit provided in the radial direction of the net surface. High speed levitation separation method.
(2) At least levitating particles and organic polymer flocculant are added to the water to be treated containing the substance to be removed and stirred to attach the flocs of the substance to be removed to the levitating particles, and then the levitating separation. The floating separation water from which the flocs flocs are removed is flowed down to a net having a larger opening than the particle size of the floating particles provided at the bottom of the floating separation part, and treated water is taken out from below the net, A high-speed levitation separation method characterized by suctioning and removing solid matter trapped in a net by a pipe-shaped suction water flow generating member having a suction slit provided so as to be rotatable in the radial direction of the net surface.
(3) The method according to (1) or (2), wherein the suction slit width of the suction water flow generating member can be enlarged / reduced by a driving mechanism.
[0007]
(4) Aggregation adhesion tank provided with a stirrer for adhering the aggregation flocs formed by the inorganic flocculant in the water to be treated containing the substance to be removed to the floating particles by the polymer flocculant And a pipe-shaped suction water flow generating member having a suction slit that is connected to the rotary means that is rotated downward by the drive means and the suction means and that is provided close to the radial direction of the net surface, is disposed at the bottom of the tank. From a water discharge part, a flotation separation tank provided with a discharge part of flocking levitation particles at the top of the tank, a flock peeling stirrer tank of flocking levitation particles discharged from the flotation separation tank, and from the flock peeling stirrer tank The floating particles from which the flocs are peeled off are washed and returned to the agglomeration and adhesion tank, and a washing tank that separates the floating particles into washing waste water. The opening of the net is determined from the particle size of the floating particles. Too large Fast flotation device, characterized in that Kushida.
[0008]
(5) Aggregation adhesion tank provided with a stirrer for adhering the aggregation flocs formed by the inorganic flocculant of the aggregation target substance in the treated water containing the removal target substance to the floating particles by the polymer flocculant If, rotary tubular suction flow occurs member having a suction slit provided rotatably by the proximity to the drive means in the radial direction of the fixed net and the net surface downward connections are disposed to the suction means, the suction A suction means connected to the water flow generating member, a discharge part of the treated water at the bottom of the tank, a floating separation tank provided with a discharge part of floating particles attached to the flock at the top of the tank, and a flotation floating surface discharged from the floating separation tank has a flock stripping stirred tank sex particles, the floating particles flock has been stripped from the flock stripping stirred tank, and a cleaning tank for separating the washing and drainage washed floating particles to be returned to the aggregated attachment tank , Fast flotation device, characterized in that is larger than the particle size of該浮above particles the mesh of the net.
[0009]
One of the points of the present invention is that levitation particles such as styrene foam having extremely high levitation force (for example, specific gravity of about 0.1) are used instead of bubbles.
That is, when aggregating flocs are floated after about 5 to 10 seconds when a polymer flocculant or an inorganic flocculant and a polymer flocculant are added and stirred while adding floating particles to the raw water and stirring. It has been found that when the substance to be removed and the floating particles are integrated to form a surface that adheres to the surface of the conductive particles and then flows into the floating separation portion, the floating separation occurs at a very high speed.
The second gist of the present invention is the point of finding a technique that can reliably prevent the floating particles such as expanded polystyrene from flowing into the treated water.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system diagram showing an embodiment of the high-speed levitation separation process of the present invention, which is of a type using a rotating net. The case where the polystyrene foam particles are used as the floating particles will be described.
When a flocculant (polymer flocculant 6 alone or a combination of inorganic flocculant 2 and polymer flocculant 6) and expanded polystyrene particles 3 are added to raw water 1 and stirred with stirrer 5 in flocculent adhesion tank 4, raw water 1 That is, the aggregated floc of the substance to be removed is combined with the expanded polystyrene particles 3. When this is caused to flow into the floating separation unit 8 of the floating separation tank 7, it is floated and separated at a high speed, and the clear treated water 11 flows out from the lower part of the floating separation unit 8.
[0011]
Next, the levitated material 12 including the group of expanded polystyrene particles 3 that floated on the surface of the water is discharged from the upper part of the levitating separation tank 7 by means of a scraper, a screw pump, a conveyor, etc., and sent to the floc peeling agitation tank 16 to be stirred. When the mixture is agitated by 17, the foamed polystyrene particles 3 are in a state of being washed with scissors and the flocs are peeled off from the particles 3.
[0012]
The thing in this state is supplied to the washer 18 and the peeling floc is washed out from the lower part (preferably a method in which a part of the raw water 1 is poured as washing water 19 from the upper of the washer 4 to wash away the floc separated). The expanded polystyrene particles (separated levitation particles) 20 from which the particles have been separated are levitated and recovered by buoyancy, added to the raw water 1 again and reused. The cleaning waste water 21 including the flocs that have been peeled off is flowed into the sewage pipe or into a thickener or a sludge treatment process.
[0013]
By the way, as a result of experiments by the present inventors, the treated water 11 contains a small amount of SS that could not be floated and separated, and a small amount of “a state in which several expanded polystyrene particles 3 adhere to the floc and the buoyancy is reduced”. Coming problems were recognized.
Therefore, if the treated water 11 is discharged out of the system as it is, good quality treated water 11 cannot be obtained. When the treated water 11 is discharged into a public water area, the polystyrene foam 3 having no biodegradability flows out into the public water area, causing environmental pollution.
[0014]
As a result of intensive studies to solve this problem, when a “rotary net 9” that is rotated by a motor 10 provided at the upper part of the floating separation tank 7 is provided at the lower part of the floating separation part 8, and the floating separation water is allowed to flow down therethrough. A small amount of the expanded polystyrene particles 3 and SS accompanying the floating separation treated water 11 are captured by the net 9, and the clear treated water 11 that does not contain the expanded polystyrene particles 3 and has less SS flows out from the lower part of the floating separation portion 8. I found it.
[0015]
Since most of the SS of the raw water 1 has already been floated and separated, the amount of solid matter captured by the net 9 is small. For this reason, the rotational speed of the net 9 is sufficient to be about several rpm, and there is no need for high-speed rotation. Moreover, you may rotate intermittently. The “net” referred to in the present invention is sometimes called a screen and means a porous water-permeable body such as a sieve.
[0016]
As a result of the experiment, it was unexpectedly confirmed that the expanded polystyrene particles 3 were surely captured even when the opening of the net 9 was considerably larger than the diameter of the expanded polystyrene particles 3. For example, when the particle diameter of the expanded polystyrene particles 3 is 0.7 mm, the expanded polystyrene particles 3 are captured by the net 9 even if the opening of the net 9 is about 6 times 4 mm.
[0017]
The reason is considered as follows.
That is, it has been found that the reason why the expanded polystyrene particles 3 that reach the net 9 without being floated and separated is that a considerably large floc adhered to the expanded polystyrene particles 3 and the adhesion rate was reduced. (It was observed that the particle diameter of the styrene particle 3 adhering floc reaching the net 9 was certainly 5 mm or more). In other words, it has been found that unless a considerably large floc adheres to the polystyrene particles 3, the flying speed of the expanded polystyrene particles 3 is not reduced but floated and separated, so that it does not reach the surface of the net 9.
[0018]
With such a mechanism, the expanded polystyrene particles 3 are captured by the net 9 having a large opening, and therefore, there is an advantage that a large amount of water can pass through the net 9 with a small resistance to water flow.
[0019]
Thus, when the operation of passing the floating separated water through the rotary net 9 is continued, the SS and the floating particles 3 are captured by the net 9, but close to the horizontal plane of the surface layer portion A of the rotary net 9, When the suction water flow generation member 13 having a slit in the radial direction is provided and the suction pump 14 is operated, a strong water absorption flow is generated in the slit of the suction water flow generation member 13. A suction water flow is generated in the slit portion of the suction water flow generating member 13 by a suction pump 14 at a flow rate of several meters / second. Naturally, the slit width is larger than the particle diameter of the expanded polystyrene particles 3. The suction tube 13 may be provided close to the lower surface of the net 9. However, in order to ensure that the treated water 11 does not include SS and the expanded polystyrene particles 3, the suction pipe 13 is preferably provided on the upper surface of the net 9. It can also be provided on both the upper and lower surfaces of the net 9.
[0020]
Due to the above action, the expanded polystyrene particles 3 do not flow out into the public water area and cause environmental pollution.
As a result, the SS and the expanded polystyrene particles 3 captured by the net 9 are discharged out of the system together with the suction drainage 15 and the net 9 is washed, so that the water flow resistance does not increase. As a result, it is not necessary to stop the operation of the floating separator for cleaning the net 9, and continuous operation can be performed.
[0021]
Since the suction drainage 15 contains the polystyrene foam particles 3 and SS, it is returned to the raw water 1 and flows into the floating separation unit 8 together with the raw water 1. In order to reduce the amount of suction drainage, the suction pump 14 is normally operated intermittently, but may be operated constantly.
[0022]
In addition, when processing the raw water 1 containing impurities according to the present invention, it is important to pay attention to the following points.
That is, in the case of raw water containing various kinds of foreign matters (paper pieces, pieces of rubber products, vegetable scraps, plastic pieces, etc.), it is preferable to remove them with a screen in advance, but some of them are still floated and separated according to the present invention. May flow into the device.
In such a case, these contaminants reach the net 5 of the present invention and are captured without being levitated and separated. However, contaminants larger than the slit width of the suction water flow generating member 13 are not sucked, but are caught by the slit and close the slit.
[0023]
In order to prevent such troubles, the present invention makes the slit width variable, intermittently widens the slit width, and sucks in the foreign matter caught. The means for making the slit width variable is arbitrary, and the slit width may be made mechanically and automatically variable by using a pneumatic actuator, a rubber bag expansion / contraction action, and the like.
[0024]
Next, if the aspirated contaminants and the floating particles 3 are returned to the raw water 1 as they are, the contaminants accumulate in the system and cause a serious problem. It is important to return the floating particles 3 to the raw water 1 after passing the particles 3 through a screen (a mesh opening of about 15 mm).
In addition, in order to separate the contaminants and the floating particles 3, precipitation separation, cyclone, etc. can be used in addition to the screen.
[0025]
Here, the optimum type of the floating particles 3 to be applied to the present invention is foamed plastic fine particles such as foamed polystyrene. In particular, polystyrene foam is optimal because it can have a very low specific gravity, has a very high levitation force, is inexpensive, and has a relatively high strength.
[0026]
According to the experiments by the present inventors, the particle size of the floating particles 3 added to the raw water 1 is preferably about 500 to 1000 μm. If the particle size is excessively large, the aggregated flocs are difficult to adhere to the floating particles 3, and if excessively small, the floating speed is decreased.
The specific gravity of the floating particles 3 is also important. Particles having a specific gravity of 0.2 or less, preferably about 0.05 to 0.2 and having a large buoyancy are suitable.
Furthermore, a preferable range for the amount of the floating particles 3 added is 20 to 300 milliliters per liter of raw water in bulk volume. More preferably, it is 30-100 (milliliter floating particle / liter raw water grade). If the amount is too small, the effect of improving the ascent rate is reduced. On the other hand, if the amount is too large, it becomes difficult to fluidize and handle the mixture.
[0027]
The appropriate addition rate of the inorganic flocculant 2 varies depending on the quality of the raw water 1. When river water is treated according to the present invention, it is about 10 to 20 mg / liter for PAC and about 3 to 7 mg / liter for ferric chloride.
[0028]
The organic polymer flocculant (polymer) 6 is anionic, nonionic, cationic, amphoteric polymer, or a combination thereof. An appropriate injection rate is about 0.5 to 1 mg / liter in the case of treating river water. The exact appropriate injection rate is determined by preliminary tests.
[0029]
Next, as another embodiment of the present invention, a method of rotating the suction member without rotating the net will be described with reference to FIG. In addition, what has the same function as what was shown in FIG. 1 is shown using the same code | symbol.
That is, a rotary suction water flow generating member that is rotated by a drive gear 24 provided at the upper part of the floating separation part 8 that has a slit in the radial direction in the vicinity of the horizontal surface of the fixed net 22 provided at the lower part of the floating separation part 8. When the suction pump 14 is operated, a strong suction water flow having a flow velocity of several meters / second occurs in the slit of the suction water flow generating member 23.
[0030]
As a result, the SS and the expanded polystyrene particles 3 captured by the net 22 are discharged from the floating separation unit 8 together with the suction drainage 15 and the filtration resistance of the net 22 does not increase. Since the suction drainage 15 contains the polystyrene foam particles 3 and SS, it is returned to the raw water 1 and flows into the floating separation unit 8 together with the raw water 1. In addition, the expanded polystyrene group 3 which floated on the water surface is processed similarly to the case of FIG. 1 demonstrated previously.
As a result of the water resistance of the net 22 being kept small by the above action, it is not necessary to stop the operation of the floating separator for cleaning the net 22, and the operation can be continued. In the apparatus shown in FIG. 2, the net may not be fixed, but the rotary net 9 shown in FIG. 1 may be used.
[0031]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[0032]
Example 1 High-speed turbidity test of river water when using a rotating net 30 Styrofoam fine particles having an average particle size of 700 μm and a specific gravity of 0.15 are added to river water in rainy weather (SS: 66 mg / liter) (milliliter / liter raw water) Add, agitate and disperse throughout the agitation tank, add 20 mg / liter of PAC, stir rapidly for 30 seconds, then add 0.5 mg / liter of anionic polymer (brand Ebagulose A151) and add 10 seconds Further, 0.5 mg / liter of amphoteric polymer (brand Ebagulose B104) was added and stirred for 10 seconds.
As a result, turbidity in the raw water adhered to the surface of the styrol fine particles. This was allowed to flow into a flotation separation tank (a cylindrical column with a diameter of 150 mm and a height of 3 m) set to a high flotation separation speed of 3000 mm / min.
As a result, the floating particles promptly floated on the water surface, the treated water SS became 8 mg / liter, and the SS in the river water was levitated and separated at an extremely high speed.
[0033]
Next, floating separation water (SS: 8 mg / liter, amount of styrene foam fine particles; 5 to 5 mm) is placed on a horizontal rotating net (stainless steel, 4 mm opening, 140 mm diameter disk) at the bottom of the floating separation tank. 13 ml / m ³ water).
Also, a pipe-shaped suction water flow member (diameter 20 mm, length 70 mm, suction slit width 2 mm, suction flow velocity in the slit part) near the upper surface of the horizontal rotating net below the floating separation tank in the radial direction (3 mm above) Was 0.5 m / sec). The cycle of operating the suction pump for 1 minute every 9 minutes was repeated.
[0034]
In this state, the floating separator was operated for 12 hours, but the water flow resistance of the net did not increase. Further, the SS of the net effluent (treated water) was always 3 mg / liter or less. Further, there was no outflow of the expanded polystyrene fine particles out of the system.
For comparison, when the operation was carried out without installing a rotary net at the lower part of the floating separation part, the expanded polystyrene particles flowed into the treated water. The amount of the outflow was 5-13 ml in terms of bulk volume of styrene fine particles per 1 m ^{3 of} treated water, which was a non-negligible amount.
[0035]
Example 2 High-speed turbidity test of river water when using a rotary suction pipe River water SS in rainy weather: Add 50 microliters of polystyrene foam with an average particle size of 700 μm and a specific gravity of 0.15 to 66 mg / liter. While stirring and dispersing in the entire stirring tank, PAC was added at 20 mg / liter, and after rapid stirring for 30 seconds, polymer (anionic polymer, molecular weight 15 million, brand Ebagulose A151) was added at 0.5 mg / liter. The mixture was stirred for 10 seconds, and 0.5 mg / liter of amphoteric polymer (brand Ebagulose B104) was further added and stirred for 10 seconds. As a result, turbidity in the raw water adhered to the surface of the styrol fine particles. This was allowed to flow into a flotation separation tank (a cylindrical column with a diameter of 150 mm and a height of 3 m) set to a high flotation separation speed of 3000 mm / min.
As a result, the floating particles promptly floated on the water surface, the treated water SS became 8 mg / liter, and the SS in the river water was levitated and separated at an extremely high speed.
[0036]
Next, floating separation water (SS 8 mg / liter, amount of expanded polystyrene fine particles: 5 to 11 ml / m ³ water) was allowed to flow into a net (aperture 4 mm) installed at the bottom of the floating separation tank.
Further, a rotating pipe-shaped suction water flow pipe (diameter 20 mm, length 73 mm, suction slit width 2 mm, the suction water flow velocity at the slit portion is 0.5 m / second, the rotation speed 3- 5 rpm). The cycle of operating the suction pump for 2 minutes was repeated once every 8 minutes.
In this state, the floating separation apparatus was operated for 12 hours, but there was no increase in the water flow resistance of the net. Moreover, SS of net effluent water (treated water) was always 2 mg / liter or less. Further, there was no outflow of the expanded polystyrene fine particles out of the system.
[0037]
【The invention's effect】
According to the present invention, the following excellent effects can be obtained.
(1) Floating separation can be performed at a very high speed, and raw water can be purified in a very short time.
(2) Since the rotary net and the suction part or the fixed net and the rotary suction pipe are provided below the floating separation part, the floating particles do not flow out into the treated water. In addition, water resistance on the net surface does not increase. The SS of treated water also decreases.
(3) Since the mesh opening of the net may be considerably larger than the floating particle size, the net water resistance is small.
(4) An air compressor, an air dissolution tank, and the like, which are indispensable in the conventional pressurized dissolved air flotation separation method, are unnecessary, and equipment costs and power costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a high-speed levitation separation apparatus of the present invention using a rotating net.
FIG. 2 is a system diagram showing another embodiment of the high-speed levitation separator of the present invention using a fixed net.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Raw water 2 Inorganic flocculant 3 Floating particle 4 Aggregation adhesion tank 5 Aggregation tank stirrer agitator 6 Polymer flocculant 7 Flotation separation tank 8 Flotation separation part 9 Rotating net 10 Motor 11 Processed water 12 Floating matter 13 Suction water flow occurrence Member 14 Suction pump 15 Suction drain 16 Flock peeling stirrer tank 17 Stirrer 18 Washer 19 Washing water 20 Separating floatable particles 21 Washing drain 22 Fixed net 23 Rotating suction water flow generating member 24 Drive gear

Claims (5)

At least levitating particles and organic polymer flocculant are added to the water to be treated containing the substance to be removed and stirred to attach the flocs of the substance to be removed to the levitating particles, and then levitated and separated at the levitating separation unit. The floating separation water excluding the aggregated floc in the floating separation is allowed to flow down to a rotary net having a larger opening than the particle size of the floating particles provided in the lower part of the floating separation part, and below the net High-speed floating separation characterized in that the treated water is taken out from the net and the solid matter trapped in the net is sucked and removed by a pipe-like suction water flow generating member having a suction slit provided in the radial direction of the net surface. Method. Add at least levitating particles and organic polymer flocculant to the water to be treated containing the substance to be removed and stir to attach the flocs of the substance to be removed to the levitating particles, and then flocculate the flocs by the flotation separation. The floating separation water excluding the water is allowed to flow down to a net having a larger opening than the particle size of the floating particles provided in the lower part of the floating separation part, and treated water is taken out from below the net, and the net surface A high-speed levitation separation method characterized by sucking and removing solid matter trapped in a net by a pipe-shaped suction water flow generating member having a suction slit, which is provided so as to be rotatable in the radial direction. The method according to claim 1 or 2, wherein the suction slit width of the suction water flow generating member can be enlarged or reduced by a driving mechanism. A coagulation adhesion tank equipped with a stirrer for adhering the aggregation flocs formed by the inorganic coagulant in the water to be treated containing the substance to be removed to the floating particles by the polymer coagulant, and below A pipe-shaped suction water flow generation member having a suction slit connected to the rotary net rotated by the driving means and the suction means and provided in the radial direction of the net surface is disposed, and the treated water is discharged to the bottom of the tank. A flotation separation tank provided with a discharge part for floc adhering levitation particles at the top of the tank, a floc exfoliation stirring tank for flock adhering levitation particles discharged from the flotation separation tank, and a flock from the flock exfoliation agitation tank exfoliated floating particles, possess a cleaning tank for separating the washing and drainage washed floating particles to be returned to the aggregated attachment tank, the mesh of the net is larger than the particle size of該浮above particles Fast flotation device, characterized in that. Aggregation adhesion tank equipped with a stirrer for aggregating flocs formed by inorganic flocculants formed by inorganic flocculants in the treated water containing the substances to be removed to floatable particles by the polymer flocculant, and suction rotary tubular suction flow occurs member having a suction slit provided rotatably by the proximity to the drive means in the radial direction of the fixed net and the net surface is downwardly connected to the means is arranged, the suction water flow occurring member A suction means connected to the tank, a discharge portion of the treated water at the bottom of the tank, a floating separation tank provided with a discharge section for floc-attached floating particles at the top of the tank, and flock-attached floating particles discharged from the floating separation tank has a flock stripping stirred tank, the flying particles flock has been stripped from the flock stripping stirred tank, and a cleaning tank for separating the washing and drainage washed floating particles to be returned to the aggregated attachment tank, the net Fast flotation device, characterized in the mesh opening that is larger than the particle size of該浮above particles.

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