JPH05131103A - Filter device - Google Patents

Abstract

PURPOSE:To release a suspended component by small-sized air supply equipment using a small amount of air by performing filtering using lumpy filter media made of a fiber and allowing the shearing force of air to effectively act on the lumpy filter media when the suspended component caught by the lumpy filter media is released by air backwashing. CONSTITUTION:Many lumpy filter media 3 made of a fiber are connected at a predetermained interval by a linear connection jig 4 to constitute one filter element 2 and a backwashing fluid is supplied from the region on the attachment side of the filter element 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration device for filtering raw water in a filtration tank by passing the raw water downward or upward.

[0002]

2. Description of the Related Art When a single filtration layer of a filtration device, or a multi-layered filtration layer in the vertical direction, is composed of anthracite having a particle size larger than that of sand and a low specific gravity, the porosity of the filtration tank is about 70%.
There are few channels through which water flows during filtration, and the turbidity components trapped in the filter layer by filtration are deposited in the vicinity of the channels and are swept away at the flow rate of water and mixed into the filtered treated water to improve the quality of the treated water. make worse. Therefore, there is a limit to the flow velocity of raw water through the filter bed, and the linear velocity of water flow is about 10 m / Hr.

In view of this point, recently, there has been known a filtering device using a substantially spherical fibrous filter material capable of passing raw water at a high flow rate. Since this fibrous block material has a porosity of 90% or more between the fibers, it can be filtered at a high flow rate with a water flow linear velocity of 20 to 80 m / Hr.

[0004]

When a filtration treatment at a high flow rate is carried out with this lumpy filter medium made of fibers, the porosity decreases due to the accumulation of suspended components trapped between the fibers, so that removal of this suspended component is effective. Must be done. Backwashing with air and water is effective for removing turbidity components as with ordinary filter media, but when backwashing with air, the fibrous lump filter media rises in the same direction as the upward flow of air. Then, the shearing force of the air for separating the suspended turbidity components trapped in the fibers from the fibers is weakened. Therefore, when backwashing a filter medium such as sand, the upward flow rate of air may be 60 m / Hr, while for backwashing a fibrous lump filter medium, the upward flow rate of air is 200 m / Hr. Since it has to be Hr and requires a large amount of air, the cost of the mechanical equipment for this in the filtration device becomes very large.

[0005]

SUMMARY OF THE INVENTION The present invention has been developed in view of the above, and a plurality of block-shaped filter media made of fibers are connected to each other with a linear connector at intervals to form a filter element. A plurality of filter elements are mounted in the filter tank at one end, and the backwashing fluid is supplied from the mounting side of the filter element.

[0006]

EXAMPLE In the illustrated example, 1 is a filter tank, and 2 is a filter element for forming a filter layer. The filter element 2 is made of fibers such as acrylic, acrylonitrile, polyester, polyamide, and vinylidene chloride and has a diameter of 20 to 100.
A plurality of spherical massive filter media 3 having a diameter of mm are connected by a linear connecting tool 4 such as a thread or a string at a predetermined interval.
The linear connecting member 4 is a bobbin-like fiber made of the same material as the lump filter medium 3, a fishing line such as nylon or tetron, and an ultrafine stainless wire. The connecting interval of the lump filter media 3 by the linear connecting tool 4 is about 1 L to 10 L with respect to the diameter L of the lump filter media between the centers of the lump filter media, and the interval may be constant, but when backwashing, a tank is used. When rising in the internal liquid, the interval may gradually increase or decrease from the lower end to the upper end. Further, the connection between the linear connecting tool 4 and the block-shaped filter medium 3 may be any method such as welding, adhesion, and tying. The total length of the filter element 2 is such that, when backwashing, part of the water in the filter tank is drained out to lower the water level, and when the filter element rises in the liquid, the bulky filter medium at the upper end is at the same level as the water level. Or it should be positioned slightly below the water level.

When the raw water is passed through the filter tank 1 in a downward flow to perform the filtering process, the lower end of one of the plurality of filter elements 2 is connected to the lower water collecting plate 5. The number of filtration elements 2 to be used is appropriately determined according to the cross-sectional area of the filtration tank 1, the downward flow velocity of raw water, and the like. When the raw water is fed into the filtration tank 1 through the water supply pipe 6, the linear connecting member of each filter element is bent by the water force of the raw water flowing downward in the tank, and the fibrous lump filter medium is pressed onto the lower water collecting plate 5. On the entire surface of the lower water collecting plate to form a filter layer by being almost evenly stacked, and the SS in the raw water is placed in the voids between the fibers of the block filter material.
And the filtered water is discharged from the take-out pipe 7 at the bottom of the tank. This filtering action is the same as the conventional one using a fiber-shaped block filter medium, and since the filter medium has a high porosity between the fibers, it is possible to perform a filtration process at a high flow rate with a downward flowing water linear velocity of raw water of 20 to 80 m / Hr. Is.

[0008] When the head loss is raised after the filtration treatment,
Alternatively, after a certain filtering treatment time has elapsed, backwashing with air and backwashing with water are regularly performed to remove turbid components captured between the fibers by the block filter medium and regenerate. For this purpose, the water supply pipe 6 and the withdrawal pipe 7 are stopped, part of the water in the tank is drained from the drain pipe 8, and then compressed air is supplied to the air diffuser 9 arranged at the bottom of the tank. As a result, air bubbles are uniformly ejected from the air diffuser 9 into the tank, and the buoyancy of the air bubbles causes the filtration element 2 to be directed to one and rises in the water from the connected lower water collecting plate 5 to the upper end of each filtration element. The lumpy filter medium of is located near the water surface in the tank, and the lumpy filter medium connected below the water surface is located below the water surface, and does not move upward. Therefore, the bubbles ejected from the air diffuser 9 and directed upward into the water in the tank float up to the surface of the water while contacting the agglomerate filter media of each filter element, and the turbid components trapped between the fibers of the agglomerate filter media form bubbles. Undergoes sufficient shearing force when coming into contact with the lump filter medium, is separated from the fibers, and floats on the water surface together with air bubbles. As a result, even if the amount of air supplied to the air diffuser 9 is small,
By effectively utilizing the shearing force of air, it is possible to effectively separate the suspended component captured by the fibrous bulky filter medium between the fibers.

After backwashing with air, next, washing water is supplied to the sprinkler 10 at the bottom of the tank, and each of the filter elements is maintained in a state of rising in the water by the washing water flowing upward in the tank. The turbid component adhered by contacting the lump fibers 3 is peeled off, and the turbid component in the water in the tank is pushed out of the wash water drain pipe 11 to the outside of the tank. When the washing step is completed in this way, water is replenished to the original water level, and after standing for a while, the filtration step is restarted.
The air backwash and the water backwash may be performed at the same time.

[0010] When 300 pieces of bulky filter media made of vinylidene chloride fiber and having a diameter of 3 cm are separately put into an experimental filtration tank having a diameter of 20 cm and a height of 1 m (A), the same filter media is used, and the same filter media is used with a tetron thread of 1 mm in diameter The lower end of 50 filtration elements with a total length of 78 cm connected at intervals of 10 cm has a diameter of 5 m.
The cleaning effect was compared and compared with the case (B) in which 150 m holes were connected to the lower water collecting plate. Sewage activated sludge treated water (SS about 20 ppm) was passed through the filter tank in a downward flow at a flow rate of 1.2 m ³ / Hr, and a washing process was performed under the following conditions after the filtration process for 5 hours. (A) (B) total (lowering the water level to 60cm) stop 10 minutes the left draining for 5 minutes the left air backwash 7Nm ³ / Hr × 15 minutes 4Nm ³ / Hr × 15 minutes Mizugyakuarai 0.9 m ³ / Hr × 20 minutes Same as on the left The results of 30 times of the tests of the above-mentioned filtration step and washing step are as shown in FIG. 2, and the differential pressure at the start of filtration is stable in (A) compared to (B). What you are doing is (A)
According to the method, the turbid component captured by the fibrous bulky filter medium is peeled off with a smaller amount of washing air than in (B).

The above description is for the case where the lower end of each filter element is connected to the lower water collecting plate and the raw water is passed through the filter tank in a downward flow. In the case of upward flow filtration in which water is passed through, one end of each filter element is attached to the upper water collecting plate. In this case, when the flow of raw water is stopped, each filter element hangs down from the upper water collecting plate due to gravity. Therefore, by supplying the backwash water from the upper part in the tank and supplying the air from the lower part into the tank, the same effect can be obtained in filtration and cleaning.

[0012]

According to the present invention, the backwashing fluid is supplied from the filter element mounting side, and the fibrous bulky filter medium connected to each filter element is moored in water, so that the backwashing air or wash water is sheared. The force can be effectively applied to the bulk filter medium to separate the suspended components trapped between the fibers. Therefore, the suspended components can be removed with a small amount of air, and the cost of the air supply facility can be kept low.

[Brief description of drawings]

FIG. 1 is an explanatory view of a state during backwashing with air by the apparatus of the present invention.

FIG. 2 is a graph of comparative experiment results showing a pressure difference at the start of water flow between the device of the present invention and a conventional device.

[Explanation of symbols]

 1 Filtration tank 2 Filtration element 3 Fiber block material 4 Linear connection tool 5 Lower water collecting plate 6 Raw water supply pipe 7 Treated water extraction pipe 8 Drain pipe 9 Air diffuser 10 Water sprinkler 11 Wash water drain pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 7112-4D B01D 29/38 C

Claims (1)

[Claims] 1. A filter element comprising a plurality of block-shaped filter media made of fibers, which are connected to each other with a linear connector at a distance.
A plurality of these filtration elements are installed in the filtration tank at one end,
A filtering device characterized in that the backwashing fluid is supplied from the mounting side of the filtering element.