JPS6347489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filtration device, and particularly to a filtration device in which the water flow direction during filtration is a horizontal flow.

In a filtration device, factors that cause suspended solids to be captured within the filter media layer include (1) mechanical sieving action, (2) surface chemical action, and (3) gravitational sedimentation action. Looking at these capture factors from the water flow direction during filtration, the above (1) and
It is thought that factor (2) is dominant, and (3) gravitational precipitation is not working effectively. Therefore, the downward flow filtration method and the upflow filtration method have inferior filtration performance in terms of removing suspended matter, so in order to obtain sufficiently clear treated water, it is necessary to reduce the filtration rate, and therefore a large amount of In order to treat the water to be treated, it is necessary to increase the volume of the filter medium layer, which poses a problem of increasing the size of the device.

Therefore, in order to effectively utilize the trapping factors (1) to (3) above, a so-called lateral flow filtration method has been proposed in which the filter layer is passed through a vertical filtration layer in a lateral flow direction during filtration.

However, although such a cross-flow filtration system is excellent in terms of filtration performance, it has the following problems in terms of backwashing. In other words, even in the horizontal flow filtration method, the backwash method requires that filtration is stopped when the quality of the treated water deteriorates due to continued filtration, and the head loss of the filter media layer increases to reach the allowable value. It has been proposed to apply a batch method in which this is carried out, and a continuous method in which the filter medium layer is continuously washed in small amounts at the same time during filtration.

In the case of the former batch method, backwash water is passed from the bottom of the filter layer in an upward flow in the opposite direction to the gravity direction, fluidizing the filter layer and removing suspended matter trapped in the filter layer. . In this case, the filter medium cannot be effectively washed unless the entire filter medium layer is fluidized.
Conventionally, in the case of lateral flow filtration, a perforated plate or a perforated pipe has been used as a device for sprinkling raw water onto a filter layer during filtration and as a device for collecting clear treated water that has passed through the filter layer. However, in the case of a perforated plate or a perforated pipe, during backwashing, backwash water flows through the perforated plate or perforated pipe in a short-circuit manner, so that the filter layer does not expand and backwashing does not occur. Therefore, in order to prevent short-circuit flow of backwash water, if the pore diameter of the perforated plate or perforated pipe is made small, for example, 0.4 mm or less,
In view of water head loss, it is required to form a very large number of holes, and it takes a lot of effort to manufacture the device.

On the other hand, the continuous method has a structure in which the filter medium layer is moved in the direction of gravity, the filter medium is continuously extracted from the bottom of the filter medium layer, the filter medium is washed by an air lift, etc., and the washed filter medium is again supplied to the top of the filter medium layer. In this continuous system, there is no need to consider the short flow of backwash water, so the device structure is simplified. Furthermore, in the case of the batch method, a large amount of backwash water is required in a short period of time, and a large amount of backwash wastewater is discharged at the same time, so a backwash water tank and a backwash wastewater tank must be installed to store this water. In this case, there is no need for a storage tank, which has the advantage of reducing construction costs.

However, in the conventional continuous system, all of the filter media layers are moved continuously, so even if the amount of washing water is 2 to 3 times that of the batch system, the turbidity cannot be sufficiently captured.

An object of the present invention is to eliminate the drawbacks of the prior art described above, to provide a filtration device of a lateral flow continuous filtration type that has good quality of treated water, can reduce the amount of broken water after washing, and has a simple device structure.

The present invention provides a filtration device in which the flow direction of raw water during filtration is made into a horizontal flow and passes through a filter layer, in which a moving layer portion is provided on the raw water sprinkling side to move the filter material in the direction of gravity, and the raw water sprinkling side is closer to the raw water sprinkling side than the moving layer portion. A filter medium fixed layer section is provided on the outside separated from the moving layer section through the porous plate, and when cleaning the filter medium, the moving layer section is continuously washed during filtration, and the fixed layer section is fixed in the direction of gravity when filtration is stopped. It is designed to be moved and cleaned intermittently.

Embodiments of the present invention will be described below based on the accompanying drawings.

This filtration device consists of a filtration tower 1 whose central part is formed into a cylindrical shape, and whose upper and lower parts are formed into a circular ring shape and an inverted round cylinder shape, respectively. A water sprinkler device 2 consisting of a closed cylindrical louver is provided. A cylindrical partition plate 3 is provided at a predetermined distance from the water sprinkler 2, and a cylindrical partition plate 4 is provided at a predetermined distance from the partition plate 3. These partition plates 3 and 4 are provided with a large number of holes having a diameter of about 3 to 10 times the particle size of the filter medium particles. Furthermore, partition plate 4
Cylindrical louvers 5 are provided at a predetermined interval. The required length of the louver 5 is selected in consideration of the angle of repose of the filter medium. In this way, the inside of the filter tower 1 is divided into cylindrical spaces A, B, C, and D in sequence from the center along the outer periphery.

A main discharge control valve 6 is provided at the lower end of the filter 1, and a sub-discharge control valve 7 is provided at the lower end of the partition plate 3. The sub-discharge control valve 7 connects the annular plate to the partition plate 3.
The filter is configured to move vertically along the annular plate to form a gap g between the lower end of the annular plate and the inner surface of the cone portion of the filter tower 1. Further, a plurality of discharge pipes 8 are communicated with the bottom of the column forming the space C, and a discharge valve 9 is interposed in the middle of these discharge pipes 8. The discharge pipe 8 is connected to an air lift pipe 11 together with a discharge pipe 10 connected to the main discharge control valve 6 . An air blowing pipe 12 is connected to the air lift pipe 11, and it communicates with a separation tank section 13 provided at the upper part of the filtration tower 1.

Spaces A, B, and C of such a filtration device are filled with filter media, and spaces A and B are filled with moving layers A and B, respectively.
B, the space C is a fixed layer C. Then, the raw water containing suspended solids is sprayed radially from the water sprinkling device 2 onto the filter media layer in a horizontal flow, and the suspended solids are removed in the process of passing through the moving layers A, B and fixed layer C, and the treated water passes through the louvers 5. The water is then collected through a water intake device consisting of a space D and discharged to the outside of the filtration tower 1. After much of the suspended solids (relatively large suspended solids) in the raw water are removed in moving bed sections A and B, relatively small suspended solids are further captured in fixed layer section C, which then undergoes finishing treatment. Therefore, the turbidity concentration in the treated water is 10mg/
It is kept clear with less than 2 mg/g of water. Looking at the amount of suspended solids captured in the moving layer parts A and B along the water flow direction, the closer to the water sprinkler, the greater the amount. That is, the amount of suspended solids trapped in the moving layer section A is larger than that in the moving layer section B.

In this embodiment, by operating the main discharge control valve 6 and the sub-discharge control valve 7, the moving speed of the filter medium in the entire moving layer is controlled, and the moving speed of the filter medium in the moving layer A is changed to the moving speed of the filter medium in the moving layer B. The speed of movement is controlled to be greater than the speed of movement. Therefore, since the moving speed can be controlled depending on the amount of suspended solids captured in the moving layers A and B, the amount of waste water consumed for cleaning can be minimized.

Here, in the moving layer part, a phenomenon occurs in which the suspended solids that have been filtered once are separated during the movement of the filter medium, and this separated suspended solid is gradually transferred to the water collection side by the cross current and is captured in the fixed bed, so the moving bed A relatively large amount of suspended matter is captured at the interface between the solid layer and the fixed layer. Therefore, when the pore size of the partition plate 4 is set to 3 to 10 times the particle diameter of the filter medium, a displacement effect occurs on the filter medium near the interface between the moving layer and the fixed layer, so that the fixed layer is regenerated near the interface. Further, even if some filter medium particles enter between the moving layers, the filtration performance is not significantly affected, so it is sufficient to make the pore size of the partition plate 3 3 to 10 times the filter medium particle size. Since the hole diameters of the partition plates 3 and 4 can be made relatively large in this manner, the increase in pressure loss ΔP can be reduced.

Next, the cleaning action of the filter medium will be explained. first,
Regarding cleaning of the filter media in the moving bed section A, the filter media that has passed through the main discharge control valve 6 is vigorously stirred within the air lift tube 11, so that the suspended solids adhering to the filter media are completely peeled off before being transferred to the separation layer 13. The suspended solids are separated from the filter material based on the difference in specific gravity and particle size.
The filter medium is sent into the filter tower again. Suspended matter is separated layer 1
The water is discharged from an overflow pipe 14 provided at the top of 3. After passing through the sub-discharge control valve 7, the filter medium of the moving bed B passes through the main discharge control valve 6, where the suspended solids adhering to the filter medium are removed in the same manner as described above, and the filter medium is sent to the filtration tower 1 again. In this way, the moving layer parts A and B are washed simultaneously during filtration. In this case, water spray during filtration does not flow back into the separation tank 13 due to the seal zone (having an inclination angle based on the angle of repose of the filter medium) shown by E in FIG.

Regarding cleaning of the filter medium in the fixed bed section C, the frequency of cleaning is appropriately determined based on the turbidity concentration of the raw water, the allowable value of the turbidity of the treated water, and the like. When cleaning the fixed bed, stop the supply of raw water, collection of treated water, and movement of the filter media in the moving bed sections A and B, open the discharge valve 9 for the filter media in the fixed bed C, and drain the air lift pipe from the drain pipe 8. 11, the filter medium of the fixed bed C is supplied. Thereafter, the filter material, which has been washed in the same manner as the filter materials of the moving layers A and B, and from which the suspended solids have been removed, is placed in the filter tower 1.
will be introduced in At this time, since the moving beds A and B are filled with filter media, the filter media introduced into the filter tower 1 enters the space C and forms the fixed bed C.

In the above embodiment, the moving layer section is divided into two layers through a perforated plate, but the moving layer section is made to have three or more layers, and the moving speed of the filter medium is made smaller as the moving layer moves away from the sprinkler side. Alternatively, there may be only one moving layer. Furthermore, instead of a water sprinkler device consisting of a cylindrical louver, a pipe in which a number of holes or slits are formed can be used. Further, in the above embodiments, a water intake device made of louvers is used, but a partition plate in which a large number of holes or slits are formed may also be used. Further, when a pipe having a large number of holes or slits is used in the water sprinkling device, a discharge valve may be provided to discharge the filter medium when it enters the water sprinkling device.

As described above, according to the present invention, the moving bed section can be cleaned at the same time as filtration, and there is no need to fluidize the filter medium layer, so the water sprinkler and water collection device can be simplified. Since a part of the filter medium layer (fixed layer) only needs to be washed intermittently, the filtration process can be carried out efficiently while reducing the amount of washing waste water.

[Brief explanation of the drawing]

Fig. 1 is a side configuration diagram showing an example of the present invention;
The figure is a sectional view taken along the line -- in FIG. 1... Filter tower, 2... Water sprinkler, 3, 4... Partition plate,
5... Louver, 6... Main discharge control valve, 7... Sub-discharge control valve, 8, 10... Discharge pipe, 9... Discharge valve, 11... Air lift pipe, 12... Air blowing pipe, 13... Separation tank.

Claims (1)

[Scope of Claims] 1. In a filtration device in which raw water passes through a filter layer with the flow direction of raw water as a horizontal flow during filtration, a moving layer portion for moving the filter material in the direction of gravity is provided on the raw water sprinkling side, and A filter medium fixed layer is provided on the outside away from the raw water sprinkling side via the moving layer part and the porous plate,
A horizontal counterflow filtration device characterized in that the outside of the fixed layer is the water collection side. 2. The transverse flow according to claim 1, wherein the moving layer is composed of two or more layers, and the moving speed of the filter medium in each of these moving layers is decreased from the raw water sprinkling side to the filter medium fixed layer side. type filtration device. 3. The horizontal direction according to claim 1, wherein the filter medium in the moving bed is configured to be introduced into the upper part of the filter tower through an air lift pipe after being extracted from the filter tower. Fluid filtration device.