JP3790857B2 - Filtration apparatus and filtration method using floating filter medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, water containing substances to be removed such as suspended particles such as industrial waste water and sewage, phosphate ions, fluorine ions, metal ions, chromaticity components, and COD components (this is referred to as “raw water” in this specification). The present invention relates to a filtration device and a filtration method. INDUSTRIAL APPLICABILITY The present invention can be continuously implemented as a high-speed solid-liquid separation technology for sewage that flows into a sewage treatment facility, particularly, rainwater overflow (abbreviated as CSO) in a combined sewer that contains organic suspended particles. This is a preferred technique.
[0002]
[Prior art]
Recently, the pollution load on the public water area of rainwater overflow (CSO) in the combined sewer has become a big problem. Since rainwater overflow (CSO) in a combined sewer generates a huge amount of water in a short time, a device that can remove CSO contaminants with a very compact device is eagerly desired.
[0003]
In addition, the sewage flowing into the sewage treatment facility is first precipitated and separated in the settling basin and then treated with activated sludge. However, since the SS removal rate of the first settling basin is poor, a coagulant is added to perform coagulation sedimentation treatment. Examples are prevalent in Scandinavia. However, there is a drawback that the coagulation sedimentation rate is small and a large sedimentation basin is required. Therefore, a new technology capable of solid-liquid separation of CSO and sewage at high speed is desired.
[0004]
As shown in FIG. 2, in the prior art “filtering device for filter media in a continuous filter using floating filter medium”, a separation tank 31 for separating the filter medium and sewage is provided below the filter tank 21 filled with the floating filter medium 22. Provided, and the communication portion with the filtration tank 21 can be freely opened and closed. On the other hand, a filter cleaning pipe 29 is formed between the top of the filtration tank 21 and the separation tank 31, and the cleaning pipe 29 can be opened and closed. In addition, the separation tank 31 is provided with a filter medium cleaning device in a filter using a floating filter medium, which is provided with a sewage extraction pump 33.
[0005]
[Problems to be solved by the invention]
However, as a result of conducting an additional test of this prior art, there were the following drawbacks.
1) Since the filter medium is washed intermittently, continuous filtration cannot be performed.
2) A large number of valves (30, 32, 34, etc.) are required, and the opening and closing operation of the valves is complicated. Valve opening / closing control equipment is also required.
3) Since the uppermost part is not cone-shaped, the floating filter medium is strongly pressed against the cover at the top of the apparatus by a buoyant force and is in a fixed layer state. Only will be inhaled.
4) Since a complicated separation tank 31 having a double cone shape must be provided at the lower part of the filtration device, the device production is troublesome and the production cost is high.
[0006]
The present invention is an improvement of the above-described prior art by a device with a very simple configuration, and suspended particles in various raw water such as river water, lake water, drainage, sewage, phosphate ions, fluorine ions, metal ions, It is an object of the present invention to provide a technology capable of filtering and separating substances to be removed such as chromaticity components and COD components at high speed.
[0007]
[Means for Solving the Problems]
The present invention has solved the above-described problems by the following means.
(1) It comprises a tank having a taper part that forms a fluidized part of the upper floating filter medium and a straight body part that forms a filtration layer comprising a packed bed of the floated filter medium following the lower part of the fluidized part, and the top part of the taper part The raw water inflow section arranged in the filter section, a filter medium suction pipe for sucking the floating filter medium from the floating filter medium flow section of the tapered section, and a floating filter medium sent from the suction pipe via a suction pump are introduced below the filtration layer. Filtration using a floating filter medium, characterized by having a filter medium cleaning chamber with an upper opening disposed, a filtrate drainage provided at the bottom of the tank, and a cleaning drainage pipe installed at the bottom of the filter medium cleaning chamber apparatus.
(2) the raw water flow rate Q, Q ₁ a filter material suction water, when the washing waste water discharge flow rate Q _2, above, wherein the set to _{Q 1 <Q 2 << Q (} 1) filtration device as claimed .
[0008]
(3) A floating portion of the floating filter medium is formed in the upper tapered portion, and raw water is introduced from the top of the tapered portion of the filtration tank in which a filtration portion composed of a packed bed of the floating filter material is formed below the flowing portion. Then, the flow part and the filtration part are allowed to flow downward, the floating filter medium is sucked out from the intermediate position of the taper part and taken out to the outside, and the filtered medium washing chamber having an upper opening provided with the removed floating filter medium below the filtration part After washing and floating to the bottom of the filtration unit, the washing waste water is discharged from the filter material washing chamber, the treated water is taken out from the lower part of the filtration tank, the raw water flow rate is Q, the filter material suction water flow rate is Q ₁ , and the washing waste water discharge flow rate. when to the Q _2, filtration wherein the set to Q ₁ <Q ₂ << Q.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the main part of the continuous filtration device of the present invention.
The main structure of the device of the present invention will be described.
The filtering device 1 has a cylindrical shape with a central portion forming a straight body portion 3, and an upper portion with a tapered shape (conical shape) to form a tapered portion 2. A raw water inflow portion 8 is connected to the top of the taper portion 2, and raw water 7 enters from there and flows downward.
[0010]
The filtration apparatus 1 is filled with floating particles (foamed plastic particles or the like) 4 having a specific gravity smaller than that of water as a filter medium. In the taper part 2, the descending flow rate of the raw water is large, and the flow rate is larger as it is closer to the top part. Therefore, the floating filter medium 4 is fluidized to form the fluidized part 5.
Since the lower tank straight body portion 3 has a lower flow rate of the raw water than the tapered portion 2, the floating filter medium 4 constitutes the packed bed 6 in a state close to the fixed bed. This forms the filtration layer 6 (this is referred to as a “filled layer” when referring to a state, and is referred to as a “filtration layer” when referred to in terms of action). However, in the portion in contact with the fluidized portion, an expanded layer having a small expansion rate may be formed by the force of the raw water fluidized. A filtered water outflow portion 15 is installed below the filtration layer 6.
[0011]
A filter medium suction pipe 9 is installed in the tapered portion 2 and connected to the pump mechanism 10. In addition, the opening of the filter medium suction pipe 9 can be provided near the center of the fluidized part 5 as shown in FIG. A filter medium transfer pipe 11 connected to the pump mechanism 10 is connected to a filter medium cleaning chamber 12 below the floating filter medium packed bed 6. The chamber 12 is open at the top and a cleaning drain pipe 13 is attached to the bottom. Since the floating filter medium 4 fed into the chamber 12 from the filter medium transfer pipe 11 has a small specific gravity, it rises in the filter tank from its upper opening and is supplied under the floating filter medium packed bed 6.
A drain pump 14 is connected to the drain pipe 13.
The above is the basic configuration of the continuous filtration device 1 of the present invention.
[0012]
Next, the principle of operation will be described.
The raw water 7 to be treated flows into the upper tapered portion 2 of the filtration device 1 of the present invention.
The descending flow rate of the raw water 7 in the straight body part 3 of the apparatus is set to be smaller than the rising speed of the floating filter medium 4 so that a packed layer (expanded layer or fixed layer) 6 of the floating filter medium 4 is formed. The filling height of the filtration layer 6 in the straight body part 3 is usually about 1 to 2 m.
[0013]
After the raw water 7 passes through the fluidized part 5, it flows through the floating filter medium packed bed (filtered layer) 6 in a downward flow. At that time, suspended particles are filtered and removed, and the clear filtered water 16 becomes the lower part of the filtered layer 6. Spill from.
Note that the flocculant 17 may be added to the raw water 7. In this case, the aggregated floc is removed by filtration.
[0014]
Thus, the floating filter medium 4 is sucked from the filter medium suction pipe 9 connected to the taper portion 2 by an arbitrary pump mechanism 10 and introduced into the filter medium cleaning chamber 12 below the filter layer 6 through the filter medium transfer pipe 11.
It is important that the upper end of the filter medium suction pipe 9 is positioned not in the packed layer portion (portion where the floating particles form the expanded layer or the fixed layer) of the apparatus body 3 but in the tapered portion 2. It is. This is because the buoyant particles 4 flow because the descending flow rate of the raw water is higher than the levitating speed of the levitating particles (floating filter material) 4 in the taper portion 2. This is because it can be sucked easily.
[0015]
After entering from the filter medium suction tube 9, the SS attached to the floating particles 4 is peeled off by a shearing force of the pump 10 or the like. Of the levitating particles 4 and SS discharged into the chamber 12, the levitating particles 4 rise upward from the upper opening of the chamber 12, reach the lower interface of the filter medium packed layer 6 and stop. At that time, a part of the filtered water flowing down from the filtration layer 6 along with drainage from a washing drain pipe 13 to be described later enters the upper portion of the chamber 12 and becomes counterflowing with the levitation particles 4 that just float up. 4 is washed with filtered water. Then, the SS component that has entered the chamber 12 settles at the bottom of the chamber 12 or is in a floating state.
When water is discharged out of the system from the washing drain pipe 13 provided near the bottom of the chamber 12, a part of the filtered water 16 flows into the chamber 12, so the SS separated from the floating filter medium 4 is discharged out of the system. Is effectively discharged outside the system. This discharged water is called washing waste water. Therefore, the trouble that exfoliation SS mixes with filtrate 16 and filtrate water SS increases does not occur. The drainage of the cleaning wastewater may be performed continuously or intermittently.
[0016]
In this case, when the filter medium suction water amount is Q ₁ and the washing drainage flow rate is Q ₂ , the separation SS can be surely excluded from the system by setting Q ₂ > Q ₁ . In particular, when the raw water flow rate is Q, and when Q ₁ << Q ₂ << Q is set, the separation SS can be more reliably excluded from the system. Q ₁ is preferably 5 to 6 m / min or less.
With such a mechanism, the floating filter medium 4 constituting the floating filter medium filtration layer 6 circulates from the upper surface to the lower surface of the filtration layer 6, so that the entire packed bed gradually moves from the bottom to the top.
[0017]
Therefore, the floating filter medium packed bed becomes a moving bed, and the filtration treatment by the moving bed can be realized extremely simply with a simple configuration. Therefore, the SS trapped by the filter medium at the upper part of the filtration layer is separated from the floating filter medium via the filter medium suction pipe and discharged out of the system by washing wastewater. Since the filtration layer is formed again, the filtration layer is constantly renewed, so that continuous filtration can be performed while maintaining a constant filtration resistance without greatly increasing the filtration resistance.
[0018]
As a result of various investigations on the optimum floating particles 4 to be applied to the continuous filtration of the present invention, it is important to use the one having the smallest possible specific gravity of the floating particles 4 in order to obtain a large filtration rate. A value of 0.2 or less was found to be suitable. In particular, expanded plastic fine particles such as expanded polystyrene, especially expanded polystyrene, can be extremely small in specific gravity, have extremely high levitation force, are inexpensive and are easily available, and are optimal.
[0019]
The particle size of the floating filter medium 4 is also an important factor. If the particle size is excessively large, SS is likely to leak. On the other hand, if the particle size is excessively small, the filtration resistance increases, so a particle size of about 0.5 to 5 mm is preferable.
The optimum moving speed from the bottom to the top of the filtration layer varies greatly depending on various conditions. However, in principle, when the raw water SS is large, the suction amount Q of the floating filter medium 4 to the downflow generation conduit is Q. increasing the _1, when the raw water SS is small, reducing the suction amount Q _1. This is because when the amount of the raw water SS is large, the upper surface of the filtration layer that first filters the raw water is clogged quickly, so that the floating filter medium 4 on the upper surface portion needs to be updated quickly.
[0020]
【The invention's effect】
According to the present invention, the following effects can be obtained.
1) A large number of valves as in the prior art are not required at all, and a very simple apparatus shape and configuration enables continuous filtration at a high filtration rate while using a filtration layer as a moving bed.
2) It is extremely suitable for raw water that generates a huge amount of water in a short time, such as rainwater overflow (CSO) in confluent sewers, and is a very compact device that does not necessarily require the use of flocculants. Cloudy particles can be removed effectively.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory drawing showing an embodiment of a filtration apparatus using a floating filter medium of the present invention.
FIG. 2 is a schematic explanatory view of a configuration of an example of a continuous filter using a conventional floating filter medium.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Filtration apparatus 2 Tapered (cone) part 3 Straight body part 4 Floating filter material 5 Filter material flow part 6 Separation tank 7 Raw water 8 Raw water inflow part 9 Filter medium suction pipe 10 Extraction pump 11 Filter medium transfer pipe 12 Filter medium washing chamber 13 Washing drain pipe 14 Pump 15 Filtration water outflow part 16 Filtration water 17 Flocculant 21 Filtration tank 22 Floating filter medium 23 Filtration layer 24 Raw water 25 Raw water supply pipe 26 Fountain port 27 Filtration water 28 Floating filter medium (floating particle)
29 Cleaning pipe 29a Cleaning chamber 30 Valve 31 Separation tank 32 Valve 33 Pump 34 Valve 35 Cleaning drainage Q Raw water flow rate Q ₁ Filter medium suction water flow rate Q ₂ Cleaning drainage discharge flow rate

Claims (3)

It comprises a tank having a taper part that forms a fluidized part of the upper floating filter medium and a straight body part that forms a filtration layer comprising a packed bed of the floated filter medium following the lower part of the fluidized part, and is disposed at the top of the taper part. The raw water inflow section, the filter medium suction pipe for sucking the floating filter medium from the floating filter medium flow section of the tapered section, and the floating filter medium introduced from the suction pipe via the suction pump are introduced below the filtration layer. A filtration apparatus using a floating filter medium, comprising a filter medium cleaning chamber having an upper opening, a filtered water discharge unit disposed at a bottom of the tank, and a cleaning drainage pipe installed at a lower part of the filter medium cleaning chamber. The raw water flow rate Q, filter media suction water flow rate Q _1, when the washing wastewater discharge flow rate Q _2, the filtration apparatus of claim 1, wherein the set to Q ₁ <Q ₂ << Q. Forming a floating part of the floating filter medium in the upper taper part, introducing raw water from the top of the taper part of the filtration tank in which a filtration part composed of a packed bed of floating filter medium is formed below the fluid part, The fluidized part and the filtering part are allowed to flow downward, the floating filter medium is sucked out from the intermediate position of the taper part and taken out to the outside, and the extracted floating filter medium is introduced into a filter medium cleaning chamber having an upper opening provided below the filtering part. After washing, float up below the filtration unit, discharge the washing wastewater from the filter media washing chamber, take out the treated water from the lower part of the filtration tank, feed the raw water flow rate Q, filter material suction water flow rate Q ₁ , wash wastewater discharge flow rate Q ₂ In this case, the filtration method is characterized in that Q ₁ << Q ₂ << Q is set.

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