JP7312044B2 - Filtration device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a filtering device for removing suspended solids and the like in a liquid, and more particularly to a filtering device suitable for suppressing reduction of filter media inside the filtering device.

Filtration devices have been conventionally used as water treatment equipment for separating and removing suspended solids and the like in liquids. This type of filtration device is constructed by laminating a support layer (support gravel layer) and a filter layer (filter material layer) in a filter tower, and is used in the fields of water treatment and sewage treatment, for example. Filtration methods using a filtration device include a downward flow type and an upward flow type depending on the filtration direction. That is, there are a method of supplying raw water from the filter layer side and taking out treated water from the lower side of the support layer, a method of supplying raw water from the support layer side and taking out the treated water from the filter layer side, and the like.

On the other hand, this type of filtering device is provided with a filtering medium cleaning device for removing suspended solids and the like adhering to the filtering medium and the like. The filter media cleaning device includes, for example, an air supply means for aerating the inside of the filter layer from the support layer side, a cleaning water supply means for cleaning (backwashing) the filter media, and the like. The filter medium is fluidized and washed with water, and the washing water after washing is discharged from, for example, the upper part of the filter tower.

JP-A-10-235106 Utility Model Registration No. 3090407

However, in the above-described conventional filtering device, there is a problem that the amount of filter material is reduced while the above-described filtration treatment and washing treatment are repeatedly performed, and as a result, the cost of replenishing the filter material increases. was unknown. Moreover, neither the above-mentioned Patent Documents 1 nor 2 mentions the reduction of the filter medium.

SUMMARY OF THE INVENTION An object of the present invention is to provide a filtering device capable of effectively suppressing reduction of filter media.

The inventors of the present application initially thought that the reason for the decrease in the amount of filter media was that part of the filter media flowed out together with the treated wastewater after washing. However, it has been found that this alone causes an unexplainable reduction in the amount of filter media. The inventors of the present application further investigated the reason and found another cause (another cause) of the decrease in filter media. The reason for this will be described below with reference to FIGS. 7 and 8. FIG.

FIG. 7 is a schematic side sectional view of a conventional filtering device 100. FIG. The figure shows the state during cleaning of the filter medium. As shown in the figure, the filtration device 100 includes a support layer 103 and a filtration layer 105 in a filtration tower 101, and an air introduction pipe 107, a washing water introduction pipe 109, and a treated water extraction pipe in the lower part of the filtration tower 101. 111 , and a raw water introduction pipe 113 and a washing drainage pipe 115 are connected to the upper part of the filtration tower 101 . In the filtration step, raw water is introduced into the filtration tower 101 from the raw water introduction pipe 113 and passed through the filtration layer 105 and the support layer 103 to remove suspended solids and the like, and the treated water after removing the suspended solids is discharged from the treated water extraction pipe 111 . On the other hand, in the washing process, air is introduced from the air introduction pipe 107 for aeration, and washing water is introduced from the washing water introduction pipe 109 to flow the filter media as indicated by the arrows shown in FIG. The suspended solids and the like adhering to the filter medium are separated by this, and the separated suspended solids and the like are discharged from the cleaning drainage pipe 115 .

In the washing process, a swirling flow is generated in the filter layer 105 as indicated by arrows in FIG. This swirling flow raises the filter media near the center, moves radially outward, and then descends along the inner wall 101 a of the filter tower 101 . At this time, the velocity of the downward flow along the inner wall 101a of the filter tower 101 is high. Therefore, as shown in FIG. 8, part of the filter material R that has descended along the inner wall 101a of the filter tower 101 is displaced when the fluid changes its flow direction by about 90° on the surface of the support layer 103. , collide with the surface of the support layer 103 and penetrate into the support layer 103 . In general, the filter medium R is a soft material such as anthracite, whereas the support material constituting the support layer 103 is a hard and rough material such as gravel. The inventors of the present application have discovered that the surface wears away and becomes smaller and eventually disappears. It is considered that this phenomenon is similarly caused by the swirling flow generated by the aeration during the aerobic biofilm filtration. Therefore, the inventors of the present application created a filtering device described below.

That is, the filtration device according to the present invention includes a filtration tower, a support layer made of a support material filled in the filtration tower, a filtration layer made of a filter material filled on the support layer in the filtration tower, A filtration device comprising: water for immersing the support layer and the filtration layer; and a filter medium washing device for introducing a fluid from the support layer side to generate a swirl flow in the filter medium of the filtration layer to wash the filter medium, The filter medium is a granular filter medium having a specific gravity that sinks when immersed in the water, and has wear resistance lower than that of the support material. At the position of the boundary part separating the support layer and the filter layer so that a part of the filter medium that descends with the generated downward flow along the inner wall collides, the filter medium wear suppression that changes the flow of the filter medium inward due to the collision It is characterized by installing members.
According to the present invention, the flow of the filter media descending along the inner wall of the filter tower is changed inward (toward the center) by the filter media wear suppression member. As a result, it is possible to prevent the filter material from being worn out due to being mixed in the support material forming the support layer. That is, it is possible to effectively suppress the reduction of the filter medium.
In addition, since the flow of the filter media descending along the inner wall of the filter tower is changed inward by the filter media abrasion suppressing member, the swirling flow of the filter media within the filter layer is facilitated and the washing effect is enhanced.
In addition, although the flow path is slightly narrowed by the filter medium wear suppressing member, this increases the flow velocity of the washing water during washing, and from this point, the washing effect of the filter medium can be enhanced. Conversely, it can be expected that the amount of washing water and the amount of air during washing can be reduced.
The installation position of the filter medium wear suppressing member is preferably a position near the boundary between the support layer and the filter layer (or the boundary, or the surface layer of the support layer). If it is installed in the vicinity of this boundary line, it is possible to reliably prevent the filter media descending along the inner wall of the filter tower from colliding with or slipping into the supporting member. On the other hand, the filter medium wear suppressing member may be installed in the filter layer above the position near the boundary line between the support layer and the filter layer. This also makes it possible to change the direction in which the filter material descends inward at a position above the surface of the support layer, thereby weakening the impact force of the filter material against the support material.
The shape of the filter medium wear suppressing member is not limited, but the point is that the shape should be such that the flow of the filter medium descending along the inner wall of the filter tower can be changed inward. For example, various shapes and structures such as plate-like, bar-like, mesh-like, and tapered shapes may be used.

In addition to the above features, the present invention is characterized in that the filter medium is anthracite, activated carbon, charcoal, lime, or sand .

ADVANTAGE OF THE INVENTION According to this invention, the reduction|decrease of a filter medium can be suppressed effectively.

1 is a schematic configuration diagram showing an example of a filtration system 1; FIG. FIG. 2(a) is a plan view of the filtration tower 11, and FIG. 2(b) is a schematic side sectional view of the filtration device 10. FIG. FIG. 4 is a diagram showing the flow state of the filter medium R during the washing process or the aerobic biofilm filtration process. FIG. 4 is an operation explanatory diagram of the present invention (enlarged schematic diagram of a portion B in the vicinity of the filter medium wear suppressing member 19 in FIG. 3); FIG. 3 is a plan view of a filtration tower 11-2; Fig. 2 is a schematic side cross-sectional view of filtering device 10-3; 1 is a schematic side sectional view of a conventional filtering device 100. FIG. FIG. 8 is a conventional problem explanatory diagram (enlarged schematic diagram of part B in FIG. 7);

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a schematic configuration diagram showing an example of a filtering system 1 configured using a filtering device 10 according to one embodiment of the present invention. This filtration device 10 is a filtration device using an aerobic biomembrane filtration method. As shown in the figure, the filtration system 1 includes a filtration device 10, raw water supply means 30 for supplying raw water to the upper portion of the filtration device 10, and washing water drainage means 40 for discharging washing drainage from the upper portion of the filtration device 10. , an air supply means 50 for supplying air to the lower part of the filtering device 10 and a water supply/drainage means 60 for discharging treated water or supplying washing water from the lower part of the filtering device 10 .

FIG. 2(a) is a plan view of a filtration tower 11 that constitutes the filtration device 10, and FIG. 2(b) is a schematic side sectional view of the filtration device 10. As shown in FIG. As shown in the figure, the filtration device 10 includes a support layer 13 and a filtration layer (filter material layer) 15 arranged in this order from the bottom in a rectangular cylindrical filter tower 11, and the support layer 13 and the filtration layer 15 is immersed in water 17 .

As the support layer 13, in this embodiment, a support gravel layer in which a support material S made of gravel is spread is used. As the filter layer 15, in this embodiment, a filter layer in which a filter medium R in which aerobic microorganisms are supported on granular anthracite is spread over is used. That is, the wear resistance of the filter medium R is considerably lower than that of the support material S.

The filter tower 11 is a bottomed quadrangular prism-shaped cylindrical body, and is configured by installing a filter medium wear suppressing member 19 at a position separating the support layer 13 and the filter layer 15 on the inner wall 11a. The filter medium wear suppressing member 19 is constructed by vertically protruding a plate with the same width from the entire circumference of the inner wall 11a toward the inside.

Returning to FIG. 1, the raw water supply means 30 includes a raw water tank 31 that stores raw water, a raw water introduction pipe 33 that connects the upper part of the raw water tank 31 and the filtration tower 11, and is installed in the middle of the raw water introduction pipe 33. It comprises a raw water pump 35 , a check valve 37 and an on-off valve 39 .

The washing water drainage means 40 is configured with a washing drainage pipe 41 connected to the top of the filtration tower 11 .

The air supply means 50 includes an air pump 51 and branch pipes 53a and 53b, one end of which is connected to the discharge port side of the air pump 51 and the other end of which is branched into two, which form the lower part of the filtration tower 11 (inside the support layer 13). , and on-off valves 55a and 55b connected to the middle of the branch pipes 53a and 53b, respectively.

The water supply/drainage means 60 includes a water supply/drainage pipe 61 having one end connected to the lower portion of the filtration tower 11 (within the support layer 13) and having the other end branched into two branch pipes 61a and 61b, and the other ends of both branch pipes 61a and 61b. , an on-off valve 65 connected in the middle of one branch pipe 61a, an on-off valve 67 and a check valve 69 connected in the middle of the other branch pipe 61b, and a backwash pump 71 and Although the details will be described later, the water supply/drainage pipe 61 is a pipe that serves both as a washing water introduction pipe and a treated water extraction pipe.

Next, the operation of the filtration system 1 will be described separately for (A) a general filtration method, (B) an aerobic biomembrane filtration method, and (C) a cleaning method common to both filtration methods. The filtration device 10 shown in FIGS. 1 and 2 above shows a filtration device using an aerobic biofilm filtration method, but in the case of a general filtration method, the on-off valve 55a and the branch pipe 53a are unnecessary. As the filter medium R, it is not necessary to use a filter medium carrying aerobic microorganisms, and a general filter medium is used.

(A) General Filtration Method For general filtration, first, the on-off valves 39 and 65 are opened, and the on-off valves 67 and 55b are closed. In this example, as described above, the on-off valve 55a and the branch pipe 53a are not installed.

When the raw water pump 35 is activated, the raw water in the raw water tank 31 is introduced into the upper part of the filtering device 10 through the raw water introduction pipe 33 .

As a result, the raw water introduced into the filtration device 10 passes through the filtration layer 15 and the support layer 13 by gravity, and is filtered to remove suspended solids and the like as treated water (treated water). It is discharged into the treated water tank 63 through the branch pipe 61a of the water supply/drainage pipe 61 and stored therein. At this time, the water supply/drainage pipe 61 functions as a treated water extraction pipe.

(B) Aerobic Biofilm Filtration Method When performing aerobic biofilm filtration, first, the on-off valves 39, 55a, and 65 are opened, while the on-off valves 67 and 55b are closed.

When the raw water pump 35 is activated, the raw water in the raw water tank 31 is introduced into the upper part of the filtering device 10 through the raw water introduction pipe 33 . At this time, the air pump 51 is started at the same time to introduce air into the support layer 13 of the filter 10 for diffusion, thereby keeping the inside of the tank in an aerobic state and creating an environment suitable for aerobic microorganisms.

As a result, the raw water introduced into the filtration device 10 passes through the filtration layer 15 and the support layer 13 by gravity, and is filtered to remove suspended solids and the like as treated water (treated water). It is discharged into the treated water tank 63 through the branch pipe 61a of the water supply/drainage pipe 61 and stored therein. At this time, the water supply/drainage pipe 61 functions as a treated water extraction pipe.

In the case of this device, biological treatment can be performed at the same time as physical filtration treatment, so not only SS (suspended solids) but also BOD (biochemical oxygen demand), COD (chemical oxygen demand), odor, chromaticity, Coliform counts can also be reduced.

(C) Cleaning Method When cleaning (backwashing) the filtering device 10, first, the on-off valve 39, the on-off valve 65, and the on-off valve 67 are closed, and the on-off valve 55b is opened. In the case of the aerobic biofilm filtration method, the on-off valve 55a may be further opened.

Then, the air pump 51 is activated to introduce air into the support layer 13 of the filter device 10 to aerate the filter layer 15 . This loosens the filter medium R in the filter layer 15 . Next, while performing the aeration, the on-off valve 67 is opened and the backwash pump 71 is started. As a result, the treated water (in this case, washing water) in the treated water tank 63 is introduced into the support layer 13 in the filter device 10 through the branch pipe 61 b of the water supply/drainage pipe 61 . At this time, the water supply/drainage pipe 61 functions as a cleaning water introduction pipe. As a result, the filter medium R constituting the filter layer 15 is brought into a fluid state as shown in FIG. The peeled off suspended solids and the like are discharged together with the treated water (wash water) from the washing drainage pipe 41 shown in FIG. Next, the air pump 51 is stopped, the open/close valve 55b (and the open/close valve 55a if opened) is closed, and the flow state is continued only by the treated water supplied from the backwash pump 71. . Also at this time, the suspended solids and the like adhering to the filter medium are peeled off, and the peeled suspended solids and the like are discharged from the washing drainage pipe 41 together with the treated water (wash water). As described above, the cleaning of the filter medium is performed. When washing is completed, the backwash pump 71 is stopped and the on-off valve 67 is closed. It should be noted that the order of supply of air and washing water and the presence/absence of supply can be changed in various ways as required.

By the way, as described above, during the washing process or the aerobic biofilm filtration process, the aeration or diffusion from the air pump 51 causes the flow of the filter medium R as indicated by the arrows in FIG. That is, an upward flow is generated in the central portion of the filter tower 11, and a downward flow is generated in the peripheral portion. A downward flow occurs along the inner wall 11 a of the filtration tower 11 . At this time, as described above, the downward flow along the inner wall 11a is fast. Therefore, as shown in FIG. 4, part of the filter material R that has descended along the inner wall 11a of the filter tower 11, when the fluid changes its flow direction by about 90° on the surface of the support layer 13, It collides with the surface of the filter medium wear suppression member 19 . In other words, it is possible to reliably prevent the filter material R from entering the support material S forming the support layer 13 . As a result, it is possible to effectively prevent the filter medium R made of a soft material from being worn away by the support material S made of a hard material. In addition, since the filter medium wear suppressing member 19 is made of metal and its surface can be easily configured to be a smooth surface, the filter medium R will not be worn even if it collides with this surface. It moves toward the inside of the tower 11 (toward the center).

Further, since the flow of the filter material R descending along the inner wall 11a of the filter tower 11 is changed inward by the filter material wear suppressing member 19, a swirl flow of the filter material R easily occurs in the filter layer 15, and the filter material R There is also an effect that the cleaning effect of is enhanced.

In addition, since the flow path is slightly narrowed by the filter medium wear suppressing member 19, the flow velocity of the treated water and the air is increased, thereby enhancing the cleaning effect of the filter medium R. Conversely, it can be expected that the amount of washing water and the amount of air during backwashing can be reduced.

As can be seen from the above cleaning method, the cleaning water drainage means 40, the air supply means 50 for supplying air used for aeration, and the water supply/drainage means 60 for supplying cleaning water are connected to the treated water from the support layer 13 side. (washing water) and air are introduced to generate a swirling flow in the filter medium R of the filter layer 15 to clean the filter medium R. As shown in FIG.

As described above, according to the filter device 10, the filter material wear suppressing member 19 is installed to change the flow of the filter material R descending along the inner wall 11a of the filter tower 11 inward when the filter material R is swirling. Therefore, reduction of the filter medium R can be effectively suppressed.

By the way, it is preferable that the area of the filter medium wear suppressing member 19 shown in the above embodiment when viewed from directly above is 15% or less of the area of the filter layer 15 when viewed from directly above. This is because if the area of the filter medium wear suppressing member 19 when viewed from directly above is increased, the effect of changing the flow of the filter medium R and preventing wear of the filter medium R is increased. Since the substantial area of the filter layer 15 is reduced, the effect of filtration performed using is likely to be reduced accordingly. As a result of consideration by the inventors of the present application, it was confirmed that the wear prevention effect of the filter medium R was obtained even when the area of the filter medium wear suppressing member 19 was set to 5%. On the other hand, it has been found that if the content is 15% or more, the water flow resistance increases, and the filtration effect may be hindered. Therefore, the area of the filter medium wear suppressing member 19 should be set to 15% or less in order to appropriately exhibit both the filtering effect inherent to the filtering device 10 and the effect of preventing the reduction of the filter media R when the filtering device 10 is washed. is more preferred.

[Second embodiment]
FIG. 5 is a plan view of a filtration tower 11-2 according to another embodiment of the invention. In the same figure, the same reference numerals are given to the same or corresponding parts as those of the filter tower 11 shown in FIGS. Matters other than those described below are the same as those of the embodiment shown in FIGS. As shown in the figure, the filter tower 11-2 is not limited to a square cylindrical shape, and may be formed in a cylindrical shape. Even with this configuration, the same effects as those of the filtering device 10 are obtained. Furthermore, although not shown, the shape of the filtration tower may be formed in a polygonal cylindrical shape or other various cylindrical shapes.

[Third Embodiment]
FIG. 6 is a schematic side cross-sectional view of a filtration device 10-3 according to yet another embodiment of the invention. This figure shows a state corresponding to FIG. In the figure, the same reference numerals are given to the same or corresponding parts as those of the filtering device 10 shown in FIGS. Matters other than those described below are the same as those of the embodiment shown in FIGS. The filtering device 10-3 shown in the figure differs from the filtering device 10 described above only in the installation position and the width dimension of the filter medium wear suppressing member 19-3.

That is, in this filter device 10-3, the filter medium wear suppressing member 19-3 is installed in the filter layer 15-3 above the position near the boundary line between the support layer 13-3 and the filter layer 15-3. . As a result, the descending direction of the filter material R-3 can be changed inward at a position above the surface of the support layer 13-3, and the filter material R-3 collides with the support layer 13-3 (support material S-3). The force can be weakened, and the mixing and abrasion of the filter medium R-3 into the support medium S-3 can be suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical ideas described in the claims, the specification and the drawings. is possible. Any shape, structure, or material that is not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as it produces the action and effect of the present invention. For example, in each of the above-described embodiments, the flat plate serving as the filter medium wear suppressing member was configured to protrude inward vertically from the inner wall of the filtration tower of a predetermined size, but it does not necessarily have to be configured to protrude vertically. You may make it protrude so that it may incline diagonally downward or diagonally upward. In the case of protruding obliquely downward, the swirling flow of the filter medium can be more easily caused. Further, the outer periphery of the filter medium wear suppressing member does not necessarily have to be in close contact with the inner wall, and there may be a predetermined gap between them. Moreover, the filter medium wear suppressing member is not limited to a flat plate shape, and may be configured in various shapes and structures such as a bar shape and a mesh shape. In short, any shape may be used as long as it can change the flow of the filter media descending along the inner wall of the filter tower inward.

Further, in each of the above-described embodiments, examples of a general filtration device and an aerobic biofilm filtration device are shown as filtration devices, but the present invention can be similarly applied to various other filtration devices. In the above-described embodiment, anthracite was used as the filter medium. Filter media of various other materials such as fiber filter media, flat oval polyester fiber filter media, polyvinylidene chloride spherical fiber filter media, and weighing fine filter media obtained by granulating and burning sewage sludge incineration ash may be used. Similarly, various materials other than gravel may be used for the material of the support material.

Moreover, the embodiments shown in the above description and each drawing can be combined with each other as long as there is no contradiction in the purpose, configuration, and the like. In addition, even if only a part of the above description and the contents of each drawing can be independent embodiments, the embodiment of the present invention is one embodiment in which the above description and each drawing are combined. is not limited to

Reference Signs List 1 filtration system 10 filtration device 11 filtration tower 11a inner wall 13 support layer S support material 15 filtration layer R filter medium 19 filter medium wear suppressing member 30 raw water supply means 40 washing water drainage means (filter medium washing apparatus)
50 Air supply means (filter medium washing device)
60 Water supply and drainage means (filter medium washing device)

Claims (2)

a filtration tower;
a support layer made of a support material filled in the filtration tower;
a filtration layer made of a filter medium filled on the support layer in the filtration tower;
water for immersing the support layer and the filtration layer;
a filter medium cleaning device for introducing a fluid from the support layer side to generate a swirling flow in the filter medium of the filter layer for cleaning;
A filtering device having
The filter medium is a granular filter medium having a specific gravity that sinks when immersed in the water and having wear resistance lower than the wear resistance of the support material,
On the inner wall of the filtration tower, at the position of the boundary separating the support layer and the filtration layer so that part of the filter medium that descends with the downward flow along the inner wall caused by the swirling flow collides. 1. A filtering device characterized by installing a filter medium abrasion suppressing member for changing the flow of the filter medium inward. A filtration device according to claim 1,
A filtration device, wherein the filter medium is anthracite, activated carbon, charcoal, lime or sand.

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