JP4529117B2 - Filtration method - Google Patents

Description

The present invention relates to a filtration method that can economically wash a bending-deformable filter medium for water treatment and also has a good washing effect .

  2. Description of the Related Art As a filtration device for removing suspended substances in a liquid to be treated, one in which a bending-deformable filter medium having one end fixed is disposed in a filtration chamber is known (see Patent Document 1).

  In the filtering device, when water to be treated is supplied to the filtration chamber from the free end side to the fixed end side of the filter medium, the water to be treated is suspended in the process of passing the filter medium. The turbid material is trapped and removed by the filter medium bent and deformed by the water flow. Further, when cleaning water is supplied into the filtration chamber in a direction opposite to the flow direction of the treated water, the filter medium bent or compressed by the water pressure of the treated water is moved in the flow direction of the cleaning water. The suspended matter that has stretched and adhered to the filter medium is washed away.

According to Patent Document 1, the fixed end of the filter medium is disposed at the lower part of the filtration chamber, and the water to be treated is flowed from the upper side to the lower side. On the contrary, the fixed end of the filter medium is disposed on the upper part of the filtration chamber, and the water to be treated is flowed from the bottom to the top, and when washing, the top is washed from the top to the bottom. It is said that water may be allowed to flow (see paragraph 0015 of Patent Document 1).
Japanese Patent No. 2803401

  However, according to the conventional filtration device and filtration method, in order to enhance the washing effect in the washing step of the filter medium, the washing medium can be pumped in a large amount to ensure that the filter medium is held in an expanded state. It was necessary. For this reason, the total amount of water required for washing | cleaning increased, and the fall of the water recovery rate and the increase in the amount of drainage were invited.

The present invention, the above such circumstances has been made as a background, it is possible to reduce the total amount of water required for cleaning of the filter medium, and cleaning effect is also good, intended to provide Filtration process how is there.

In order to solve the above problems, the filtration method according to the present invention is such that the upper end of a bendable filter medium is fixed, and a weight connected to the lower end of the filter medium provides the filter medium with a recovery force from the bend deformation. A filtration process for circulating the water to be treated from the lower part to the upper part along the filter medium, and a filter medium cleaning process for bringing a cleaning fluid into contact with the filter medium from the upper end to the lower end . The filter medium is bent by overcoming the recovery force from the bending deformation by the water to be treated, and the filter medium is stretched by the recovery force from the bending deformation in the filter medium cleaning step (claim). Item 1 ).

According to the filtration method, pre SL is water to be treated allowed to flow toward from the lower side along the filter medium to the upper side, the filter medium overcomes the recovery force from the bending deformation by該被treated water Can be bent or compressed. For this reason, the density of the said filter medium increases and the favorable filtration effect is acquired.

On the other hand, in the filter medium cleaning step, the cleaning fluid is brought into contact with the filter medium from the upper end to the lower end in a state where the filter medium is stretched by the recovery force from the bending deformation. For this reason, unlike conventional ones, it is not necessary to pump a large amount of washing water in order to extend the filter medium during washing. Therefore, the total amount of water required for cleaning the filter medium can be reduced. Further, at the time of cleaning, since the filter medium is stretched by the recovery force from the bending deformation, the cleaning effect is also improved.

As a form of preferred embodiment, fluid for the cleaning, toward from the upper side to the lower side have yo a liquid flowing along said filter medium (claim 2).

By the way, in the filtration step of the filtration method, the density of the filter medium is still small until the filter medium is sufficiently bent by the process water after the start of the water to be treated. Capturing leakage is likely to occur. For this reason, as one preferred embodiment, after the start of passing the water to be treated, the treated water that has passed through the filter medium is untreated water until the filter medium is sufficiently bent by the water to be treated. It can also be made to return to a to-be-processed water source ( Claim 3 ). In this way, it is possible to prevent the suspended matter from being mixed into the treated water after the start of passing the treated water until the filter medium is sufficiently bent by the treated water.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a filtration device suitable for carrying out the filtration method according to an embodiment of the present invention, (a) is a state when the filtration device is stopped, and (b). filtration time of state, and (c) shows the state at the time of filter material washing with backwash water.

As shown in FIG. 1, a filtration tower 1 constituting a filtration apparatus 100 suitable for carrying out the filtration method according to the present embodiment is a cylindrical body extending in the vertical direction. The upper end plate 2 and the lower end plate 32 are fixedly disposed on the inner wall surface 1a of the filtration tower 1 at intervals. Each of these end plates 2 and 3 is formed of a porous plate having water permeability. The filtration chamber 4 is surrounded by the upper end plate 2, the lower end plate 3, and the inner wall surface 1 a of the filtration tower 1, and is formed in the filtration tower 1.

  A plurality of filter media 5 that can be bent and deformed are disposed in the filter chamber 4. The number of filter media 5 arranged is such that the size of each filter media and the size of the cross-sectional area of the filter chamber 1 are such that when each filter media 5 is bent and densely packed, a necessary and sufficient filtering action is exhibited. What is necessary is just to determine suitably according to it.

Each of the filter media 5 includes a core string 6 that can be bent and deformed, and a fibrous turbidity trapping material 7 that extends radially from the core string 6 in the circumferential direction. The turbidity trapping material 7 is densely arranged around the core string 6 except for a predetermined length of each of the upper and lower portions of the core string 6. The upper end of each filter medium 5, i.e., the upper end 6a of the core thread 6 of each filter medium 5 is connected and fixed to the upper end plate 2, the lower end of each filter medium 5, i.e., the core thread of the filter medium 5 The lower end 6b of 6 hangs down in the filtration chamber 1 and naturally extends downward.

On the lower end plate 3, a weight 8 that is movable up and down in the filtration chamber 4 is placed as a common tension member for applying a recovery force from the bending deformation to each filter medium 5. The weight 8 is formed of a porous plate having water permeability. To the weight 8 is to have a slack as appropriate both, the lower end of each filter medium 5, i.e., the lower end 6b of the core thread 6 of each filter medium 5 is connected. Therefore, the filter media 5 are not tensed by the load of the weight 8. However, due to the load of the weight, each filter medium 5 is given a recovery force from bending deformation and is stretched in a natural hanging state.

  At the time of the filtration step, as shown in FIG. 1 (b), the water to be treated containing suspended substances is introduced into the filtration chamber 4 from the water tank 9 to be treated, which is the source of the water to be treated. Supplied towards. As a result, the weight 8 is pushed upward in the filtration chamber 4 by the water pressure of the water to be treated, and each filter medium 5 is bent and deformed between the upper end plate 2 and the plate-like weight 8. I'm damned. Thereby, since the density of each said filter medium 5 in the said filtration chamber 4 increases, the suspended substance contained in the said to-be-processed water is capture | acquired by each said filter medium 5 reliably. Suspended substances are removed by the respective filter media 5, and the treated water that has passed through the upper end plate 2 is discharged from the upper portion of the filter tower 1.

  In the filtration step, after the start of the water to be treated, the density of the filter medium 5 is still high until the weight 8 is pushed up by the water to be treated and the filter medium 5 is sufficiently bent. Since it is small, it is easy to cause trapped leakage of suspended solids. For this reason, as one preferred embodiment, after the start of passing the water to be treated, the treated water that has passed through the filter medium 5 is untreated until the filter medium 5 is sufficiently bent by the water to be treated. It can also be made to return to the said to-be-processed water tank 9 as water. If it does in this way, it will prevent that a suspended substance will mix in treated water after the start of water flow of the treated water until the filter medium 5 fully bends by the treated water. .

  When the supply of the water to be treated into the filtration chamber 4 is stopped, as shown in FIG. 1 (a), the weight 8 naturally descends by its own weight, and the original position on the lower end plate 3 is reached. Return to. For this reason, each said filter medium 5 is naturally extended from the said bending state at the time of a filtration effect | action.

  After the filtration step, many suspended substances are trapped and entangled with each filter medium 5. Therefore, the filter medium 5 is subjected to a cleaning action for removing the suspended substances as necessary. During the cleaning process of the filter medium 5, a cleaning fluid is brought into contact with the filter medium 5.

  As a first embodiment of the method for cleaning the filter medium 5, as shown in FIG. 1C, the upper end 6 a side to the lower end 6 b side of the filter medium 5, contrary to the flow direction of the water to be treated. The treated water can be made to flow backward as a cleaning liquid. At this time, the lower end 6b of the filter medium 5 is given a recovery force from the bending deformation by the weight 8, and has already been naturally stretched downward, so that backwash water is used to extend the filter medium 5. There is no need to pump in large quantities. For this reason, the total amount of water required for cleaning the filter medium 5 can be reduced. In addition, since the backwash water comes into contact with the filter medium 5 in a state where the filter medium 5 is stretched, the cleaning effect is also improved.

  The backwash water that has finished the filter medium cleaning action is preferably returned to the treated water source 9 together with the suspended substance separated from the filter medium 5, but may be discharged to a drainage tank (not shown).

As shown in FIG. 2, the filtration device 100 that performs the filtration method can be modified as appropriate . That is, a weight guide 12 that guides the weight 8 up and down is provided, and the weight 8 includes a weight guide insertion hole 13 that receives the weight guide 12 in a relatively movable manner. The weight guide 12 is an elongated round bar, and the upper end portion 12a is fixed to the end plate 2 at the upper portion and the lower end portion 12b is fixed to the lower end plate 3 so as to be vertically arranged in the filtration chamber 4. do it. A plurality of weight guides 12 are arranged so that the plate-like weights 8 can be smoothly guided up and down in a horizontal state, in particular, three in a uniform distribution state with respect to the weights 8. It is desirable to set it above.

  Moreover, as shown in FIG. 2, it can also be set as the structure provided with the filter medium filling part 14 in the downstream of the flow direction of the said to-be-processed water from the said filter medium 5, for example, the upper position of the said upper end plate 2. As shown in FIG. If the filter medium filling portion 14 is filled with a suitable type of filter medium, for example, a granular filter medium 15 such as sand or anthracite, the suspended substance that has passed through the filter medium 5 is transferred to the granular filter medium 15. Is surely captured. Therefore, it is prevented that the suspended substance is mixed into the treated water after the start of passing the treated water and before the filter medium 5 is sufficiently bent by the treated water. A reliable filtration function can be exhibited.

The inventors of the present invention, where the inner diameter of 1 m, using a filtration tower height 1.5m tower, the filtration method according to the present invention method and the filtration method according to the conventional method, was carried out, Table 1 The experimental results shown in Fig. 1 were obtained.

  As is apparent from the experimental results, according to the method of the present invention, the amount of backwash water is smaller than that of the conventional method, and the water recovery rate of filtration is increased.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view of the suitable filtration apparatus used in order to implement the filtration processing method which concerns on one embodiment of this invention, (a) is the state at the time of the stop of a filtration apparatus, (b) is the state at the time of filtration , and (c) shows the state at the time of filter material washing with backwash water. It is a longitudinal cross-sectional view of the filtration apparatus which concerns on the modification of FIG.

Explanation of symbols

4 Filtration chamber 5 Filter medium 6a Upper end of filter medium 6b Lower end of filter medium 8 Weight (tensile member)
9 Water to be treated 14 Filter material filling part

Claims (3)

The upper end of the filter medium that can be bent and deformed is fixed, and the water to be treated is distributed from the lower part to the upper part along the filter medium in which the filter medium is given the recovery force from the bending deformation by the weight connected to the lower end of the filter medium. A filtering step, and a filtering medium cleaning step of bringing a cleaning fluid into contact with the filtering medium from the upper end to the lower end. In the filtering step, the water to be treated overcomes the recovery force from the bending deformation and A filtering method, wherein the filtering medium is bent, and in the filtering medium cleaning step, the filtering medium is extended by a recovery force from the bending deformation. The filtration method according to claim 1, wherein the cleaning fluid is a liquid that flows along the filter medium from the upper end side toward the lower end side. In the filtration step, after the start of water passage of the treated water, until the filtering medium is sufficiently bent by the treated water, the treated water that has passed through the filtering medium is returned to the treated water source as untreated water. The filtration method according to claim 1 or 2 , characterized by the above.

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