JPH10235106A - Filtration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent water containing a suspended substance from passing through gap between a filer medium and the wall face of a filtration tower by providing an annular weir plate on a filter medium layer side near the outer peripheral edge without a drainage hole of a drainage plate, in a filtration tower which contains the filter medium, supported by the drainage plate fitted on a treated water drainage side, and installing a plate inclined into a water current direction, in an annular shape, on the inner lateral wall of the filtration tower. SOLUTION: A drainage plate 3 holding sand and a filter medium such as a fiber filter medium on the top is arranged in a filtration tower 1 capable of filtering water at a high speed, and an untreated water 2 is run through the filter medium to capture and remove a suspended substance in the untreated water 2 and thereby, a high-quality treated water 5 is obtained. The part near the outer peripheral edge of the substance player 3 has no drainage hole, and a weir plate 6 is erected upright, in an annular shape, on the filter medium layer side. Further, a flowing water 8 flowing down the inner wall face of the filtration tower 1 overflows the weir plate 6, passing through the filter medium and runs through the drainage plate 3. On the inner lateral wall face of the filtration tower 1, an inclined plate 7 which tilts into a water flow direction is arranged in an annular shape to prevent the flowing water 8 from flowing down along the inner wall face of the dilatation tower 1. Thus it is possible to prevent the suspended substance from leaking from a gap between the filter medium layer and the wall face of the filtration tower 1, even when the filtration takes plate at a high speed and thereby, realize filtration process with a high filtrating efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration device used for separating and removing suspended substances in water.

[0002]

2. Description of the Related Art Filtration has been widely used as a water treatment technique for separating and removing suspended substances in water. For example, in the field of clean water treatment, a method called rapid filtration is employed, in which raw water containing fine suspended substances is treated with a flocculant to aggregate the suspended substances, facilitate separation, and then separate by filtration. For this filtration, a two-layer filtration is generally carried out using a filter medium in which a crushed anthracite layer is formed on a sand layer at a flow rate of 5 to 7 m / hour.

[0003] In the field of sewage treatment, wastewater having a relatively large particle diameter and a high concentration of suspended substances such as activated sludge treated water is often subjected to filtration.
Coagulation before filtration is limited to special cases.
As the filter media used for this filtration, similar to the water treatment,
Sand and crushed anthracite are often used, and the water flow rate is 4 ~
A method of passing water at a high speed of 25 m / hour is generally adopted, and in sewage treatment, this method is called rapid filtration. The type of filtration device is roughly classified into a downward flow and an upward flow depending on the method of securing the filtration pressure, depending on the gravity type and the pressure type, and on the filtration direction.

[0004] In recent years, as a filter medium replacing sand and anthracite, a floatable filter medium made of expanded polystyrene resin, an acrylic long fiber filter medium, a polyester flat elliptic fiber filter medium, a polyvinylidene chloride spherical fiber filter medium, and a sewage sludge incineration ash. Granulation /
A fired lightweight fine-grained filter medium has been developed, and a filtration speed of 25 m / hour or more is possible. JP-A-4-0274
No. 95 and JP-A-6-292808 describe an ultra-high-speed filtration device using a polyester fiber filter medium.

[0005]

The fiber filter medium capable of high-speed filtration has a porosity of about 95%, and has a very low filtration resistance as compared with sand or anthracite. However,
When the water passing speed is 25 m / h or more, the head loss of the filter layer is 20 cm or more, and the head loss increases as the suspended solids accumulate in the filter medium. Depending on the method of forming the fiber filter medium, a filter medium capable of capturing finer suspended substances can also be formed.However, in this case, the head of the filter layer rises. However, a pressure type in which water flows in a downward flow under pressure is often used.

[0006] The above-mentioned fiber filter medium is placed in a filtration tower at a bed height of 100 cm.
When filled with water and passed through a pressure system, the head loss of the filter layer reaches as much as 200 cm, and the flow path in the filtration tower avoids the filter medium layer with high resistance, and the filter medium with lower resistance It is easy to pass through the gap on the wall of the filtration tower. As a result, there is a problem that a part of the suspended matter reaches the drainage port without being trapped in the filter medium, and high-quality treated water cannot be obtained.

The present invention solves the above problems and provides a filtration apparatus capable of preventing water containing suspended substances from passing through a gap between a filter medium and the wall of a filtration tower to obtain high quality treated water. It is intended to do so.

[0008]

In order to achieve the above object, the present invention provides a filtration apparatus in which a filter medium is held by a water flow plate disposed on a treated water discharge side and accommodated therein. On the filter medium layer side near the outer peripheral edge where there is no water hole of the plate, a weir plate is disposed annularly, and on the inner wall of the filtration tower, an inclined plate inclined in the water flow direction is disposed annularly. It is characterized by having.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes a filtration tower in a filtration device capable of high-speed filtration, in which a water-passing plate 3 holding a filter medium 4 is provided. 4 are accommodated. By passing the raw water 2 through the filter medium 4, suspended matter in the raw water is captured and removed, and high-quality treated water 5 having no suspended substance can be obtained.

[0010] Here, it is preferable that the size of the filtration tower 1 is determined so as to enable ultra-high-speed filtration in which the water flow rate in the filtration tower 1 is 25 m / hour or more. Also, in general, when the processing accuracy is considered, the layer height of the filter medium 4 is often about 1 m. When the backwashing efficiency at the time of backwashing is considered, a space above the filter medium layer is provided above the filter medium layer. Preferably, it is provided.

The water passage plate 3 has a water passage hole smaller than the filter medium 4 and does not pass through the filter medium, and may be of a size that allows only water to pass therethrough. However, considering air aeration during backwashing, etc. It is preferable that the weight is high enough to withstand this, and a steel grid or a punching plate is preferable. As the filter medium 4,
Various things are available, especially sand, anthracite,
A fiber filter or the like is suitable. The flow direction of the raw water in the filtration tower 1 may be a downward flow or an upward flow. Further, the filtration tower 1 can be applied to a pressure type in which the upper end of the filtration tower is sealed and pressurized, or a gravity type in which the upper end is opened.

In the present invention, there is no water passage hole in the vicinity of the outer periphery near the outer periphery of the water passage plate 3, and an annular weir plate 6 stands upright on the filter medium layer 4 side. This prevents the running water 8 flowing down the inner wall of the filtration tower 1 from immediately passing through the water flow plate 3. As a result, as shown in FIG. 2, the running water 8 flowing down the inner wall surface of the filtration tower 1 overflows the weir plate 6, passes through the filter medium 4, and passes through the water flow plate 3.

The height of the weir plate 6 and the distance between the weir plate 6 and the inner wall of the filtration tower can be appropriately selected as needed. 6
Is preferably 5 to 20% of the height of the filter medium layer. When the height of the weir plate 6 is less than 5% of the height of the filter medium layer, the suspended matter immediately overflows the weir plate 6 and the treatment efficiency is reduced.
If it exceeds 0%, suspended solids accumulate in the space between the weir plate and the wall surface of the filtration tower and are not discharged during backwashing.

The space between the weir plate 6 and the inner wall of the filtration tower is preferably as narrow as possible in consideration of the penetration of the filter medium 4 into this location and the cleaning efficiency during backwashing.
~ 150 mm is preferred. If the distance is less than 10 mm, not only the construction becomes difficult, but also the leakage of suspended solids is liable to occur. It cannot be washed.

Further, in the present invention, the filtration tower 1
An inclined plate 7 inclined in the direction of water flow is annularly disposed on the inner wall surface of the filter tower 1 so as to prevent flowing water 8 from flowing down along the inner wall surface of the filtration tower 1. In this way, by installing the inclined plate 7 in an annular shape on the inner wall of the filtration tower 1 where the filter medium 4 is stored, the water flow can flow down toward the center of the filtration tower in the water flow direction.

When the water flow is a downward flow, the inclined plate 7 is inclined downward toward the center of the filtration tower. If it is inclined upward, not only the water flow is disturbed, but also at the time of backwashing, the filter medium accumulates on the inclined plate. Although the inclination angle is not particularly limited, the formation angle with respect to the vertical plane (side wall) is preferably 15 to 60 degrees in consideration of the slipping of the filter medium and the water flow. The width of the inclined plate 7 is preferably narrower in consideration of obstacles at the time of backwashing, but the projection length on the vertical plane is preferably 5 to 20% of the diameter of the filtration tower 1. If it is less than 5%, the rectification effect of the water flow is low, and
%, It becomes a physical obstacle at the time of backwashing. The installation place of the inclined plate 7 is good in the middle of the four layers of the filter medium, and it is more desirable to install a plurality of sheets in the layer.

By installing an inclined plate inclined toward the center of the filtration tower in the filter medium layer, the water flow can be directed toward the center of the filtration tower as shown in FIG. 2, and the treatment efficiency can be further increased. The effect can be further improved by providing a plurality of inclined plates 7 in the filter medium layer.

[0018]

The present invention will be described below in more detail with reference to examples. Example A yarn obtained by assembling 192 undrawn polyester filaments having a single yarn fineness of 10.4 denier was used as a raw material, and a processed yarn obtained by bulky processing the untwisted yarn was 4
00 pieces are collected and bound (bound), and 75
A fiber filter medium cut into a substantially spherical shape except mm was formed.

A porous water-permeable plate having a large number of water holes except for the outer peripheral edge is installed 90 mm above the lower end, and an annular surface having an inner diameter of 157 mm and a height of 135 mm is provided on the upper surface of the outer peripheral edge. A weir plate is installed, and an annular inclined plate having an inclination angle of 30 degrees from the side wall surface and a projected length on a vertical plane of 30 mm is installed on the inner wall 250 mm above the water flow plate.
A filtration tower having a diameter of 00 mm and an inner diameter of 190 mm was used. On the water flow plate of this filtration tower, 120 fiber filter media were packed, and the height of the filter media layer was 1 m. Activated sludge treated water having a concentration of suspended solids (SS) of 10 mg / L is supplied from the raw water supply port, which is the only opening in the filtration tower having a closed upper end, so that the flow rate in the filtration tower is 30 m / hour. And treated water was discharged from a discharge port on the lower end side of the filtration tower. As shown by the dotted line in FIG. 3, in the present embodiment, the leakage of suspended solids from the filtration wall does not occur and the SS removal rate is 80% or more until the amount of trapped SS more than twice the conventional amount becomes 5 kg / m ^2. Was kept.

Comparative Example Water was passed under the same conditions as in the example using the same filtration apparatus as in the example except that neither the weir plate nor the water flow plate was installed. FIG.
In the comparative example, as shown by the solid line in FIG.
When the amount of S trapped was about 2 kg / m ² , leakage of suspended matter from the wall of the filtration tower started, and the SS removal rate dropped to 80% or less.

[0021]

According to the filtration device of the present invention, the water flow speed is 2
Even in ultra-high-speed filtration of 5 m / h or more, leakage of suspended solids from the gap between the filter medium layer and the wall of the filtration tower can be prevented, and the amount of suspended solids trapped in the filter medium can be increased. Filtration with high processing efficiency becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a filtration device of the present invention.

FIG. 2 is an explanatory schematic diagram showing a water flow direction in the filtration device of FIG.

FIG. 3 is a graph showing the relationship between the amount of SS trapped in a filter medium and the SS removal rate in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filtration tower 5 Treated water 2 Raw water 6 Weir plate 3 Water passing plate 7 Inclined plate 4 Filter material 8 Water flow

Claims (1)

[Claims] 1. A filter medium in which a filter medium is held and accommodated by a water passage plate provided on a treated water discharge side, and a filter medium layer near an outer peripheral edge of the filtration plate where there is no water passage hole in the water passage plate is annularly formed. A filtering device, wherein a weir plate is provided, and an inclined plate inclined in the water flow direction is provided in an annular shape on the inner wall of the filtration tower.