JP2001252506A - Method for backwashing filter member of natural equilibrium filter basin and filtering method in natural equilibrium filter basin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate the backwashing speed of the filter member of a natural equilibrium filter basin by a simple apparatus construction. SOLUTION: Two first and second siphon pipes 10, 20 are parallelly provided in place of one siphon pipe 7. A large quantity of backwashing water is discharged to a washing drain sewer 8 from a water collecting sewer 4A through the first and second siphon pipes 10, 20 to regulate the water level in the water collecting sewer 4A so as to make the same less than the height of a trough 4C and the filter member 4B is backwashed in this state. Just before a backwashing process is completed, a small quantity of backwashing water is discharged to the washing drain sewer 8 only through the first siphon pipe 10 and the water level of the water collecting sewer 4A is regulated so as to be made larger than the height of the trough 4C. By this constitution, the water level difference between a filter basin 4 and the filtered water communication sewer 5 is changed to regulate a backwashing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for backwashing a filter member of a filter in a natural equilibrium filter, a method for filtering in a filter, and a siphon device for the filter.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are cross-sectional views showing the structure of a main part of a general natural equilibrium filtration pond. In addition, in this specification, the term "natural equilibrium filtration pond" is used as a term meaning the whole system including the filtration pond.

[0003] The flow of water during filtration in this natural equilibrium filtration pond will be described with reference to FIG. First, water treated in a sedimentation basin (not shown) flows into the sewer 1.
The water in the sewer 1 flows into the outlet box 3 through the inflow siphon pipe 2, overflows from the outlet box 3, and enters the filter pond 4 via a drainage crate 4 A attached to the filter pond 4. The water that has entered the filter pond 4 is filtered by a filter member 4B including a sand layer, a gravel layer, and a water collecting block provided in the filter pond 4.
, And flows into the filtered water conduit 5 through the communication passage 4E below the filtration member 4B. The water in the filtered water conduit 5 overflows from the wall 5A separating the filtered water conduit 5 and the filtered conduit 6, flows into the filtered conduit 6, and naturally flows down from the filtered conduit 6 to a distribution reservoir (not shown). .

If the filtration is continued, the filter member 4B in the filter pond 4 is clogged. Since this appears as a rise in the water level of the filtration pond 4, in such a case, the backwashing of the filtration member 4B (hereinafter referred to as "backwashing") is performed. The procedure will be described with reference to FIG. FIG. 6 shows FIG.
It is the figure which cut | disconnected this natural equilibrium filtration pond by the cross section different from.

[0005] As the procedure, first, air is fed into the inflow siphon pipe 2 to stop the flow of water from the sewer 1 to the outlet box 3. After a while in this state,
The water level of the filtration pond 4 falls and becomes equal to the water level of the filtered water connection duct 5.

Next, the inside of the drainage siphon pipe 7 is sucked, and the water is discharged from the drainage channel 4A to the drainage box 8A attached to the washing drainage channel 8. As the water flows out from the collecting culvert 4A to the washing drain 8, the water levels of the collecting culvert 4A and the filtration pond 4 decrease, and the water level of the trough 4 provided in the filtration pond 4 is reduced.
When the height reaches C, the water level of the filtration pond 4 is maintained at that height, and only the water level of the drainage channel 4A decreases. Therefore,
Water flows from the filtration pond 4 to the drainage channel 4A via the trough 4C.

[0007] Here, the water level of the filtered water connecting duct 5 is maintained substantially constant. This is because the natural equilibrium filtration pond usually has about 6 filtration ponds, and the filtration water connection 5 is common to other filtration ponds (not shown). This is because when washing is being performed, filtration is being performed in other filtration ponds. Therefore, the water level of the filtered water conduit 5 may always be regarded as being equal to the height of the wall 5A separating the filtered water conduit 5 and the filtered conduit 6.

For this reason, water flows from the filtered water connection duct 5 to the filtration pond 4 based on the water level difference between the filtered water connection pipe 5 and the filtration pond 4. The water that has flowed into the filtration pond 4 from the filtration water connection duct 5 passes through the filtration member 4B from below to above,
As a result, the contaminants are separated from the filtering member 4B. Water contaminated with this pollutant is collected by a drainage channel 4A via a trough 4C.
To drainage pit 8A through drainage siphon pipe 7,
The water overflows from the drainage basin 8A, flows into the cleaning drainage 8, and is discharged therefrom to a cleaning drainage pond (not shown).

[0009]

According to a recent study by the present applicant, the backwashing speed is not set to a constant value as in the prior art, but is set to a predetermined value immediately before the end of the backwashing process. It has been found that by making the backwashing speed in the period up to the time point lower than the normal backwashing speed, the cleanliness of filtered water after the backwashing can be improved.

[0010] When the filtration step is started again after the backwashing, the filtration speed is reduced immediately after the filtration is started, and then the filtration speed is set to a normal speed. It has been found that can be improved.

However, the natural equilibrium filtration pond does not have a flow control mechanism such as a valve-controlled filtration pond, so once the flow of water reaches an equilibrium state at the time of backwashing or filtration, it is backwashed. It is impossible to change the speed or the filtration speed, and there is a problem that the above research results cannot be reflected.

The present invention has been made in view of the above circumstances, and realizes adjustment of the backwashing speed and the filtration speed in a natural equilibrium filtration pond by means of a device having a simple configuration, thereby purifying filtered water in the natural equilibrium filtration pond. The purpose is to improve the degree.

[0013]

Means for Solving the Problems To achieve the above object, a first invention of the present application provides a filter pond provided with a filter member and a trough disposed above the filter member, and a filter pond for the filter pond. A filtered water communication conduit communicating with the filtration reservoir by a communication passage provided below the filtration member, and a drainage conduit provided adjacent to the filtration reservoir and communicating with the filtration reservoir at a position higher than the height of the trough. A backwash drain from which the backwash water is discharged via at least one siphon pipe from the collecting drain, wherein the backwashing process is performed before the end of the backwashing step. In a first period from a predetermined time to an end time, a first drainage from the drainage culvert to the washing drainage culvert via the at least one siphon pipe.
By discharging the backwash water at a flow rate of the above, the water level of the drainage culvert is adjusted to be higher than the height of the trough. Said first through at least one siphon tube
Discharging the backwash water at a second flow rate greater than the flow rate of the drainage channel to adjust the water level of the drainage channel to be lower than the height of the trough; And the water level difference in the second period is smaller than the water level difference in the second period, and the backwash speed in the first period is smaller than the backwash speed in the second period.

[0014] The second invention of the present application is a sewer,
In a filtration method in a natural equilibrium pond comprising: an outlet box to which water to be filtered is supplied from the sewer through at least one siphon pipe; and a filtration pond to which the water to be filtered is supplied from the outlet box. In a first period from a filtration start time to a predetermined time, a first discharge from the sedimentation culvert to the outlet box via the at least one siphon pipe.
And supplying the water to be filtered at a flow rate of the second time period from the predetermined time point to the outlet through the at least one siphon pipe. Supplying the water to be filtered at a flow rate of?, So that the supply amount of the water to be filtered to the filtration pond in the first period is smaller than the supply amount of the water to be filtered to the filtration pond in the second period. It is characterized by.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] First, a first embodiment will be described with reference to FIG. In the following description, a method for adjusting the flow rate of water discharged from a filtration pond to a washing drainage channel during backwashing will be described. In the following description, the same components as those of the related art are denoted by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 1, a first siphon pipe 10 and a second siphon pipe 20 are provided in parallel across the end wall 4F of the drainage channel 4A as discharge siphon pipes. One end 11 is disposed in a drainage canal 4A (see FIG. 6), and the second end 12 is disposed in a drainage basin 8A (see FIG. 6) in the washing culvert 8. Similarly, the first end of the second siphon pipe 20 is disposed. 2
1 is disposed in a drainage channel 4A (see FIG. 6), and the second end 22 is disposed in a drainage box 8A (see FIG. 6) in the cleaning drainage channel 8.

When the technique of the present invention is applied to an existing natural equilibrium filtration pond, one of the first siphon tube 10 and the second siphon tube 20 is connected to the existing siphon tube shown in FIG. 7 can be diverted.

A pipe 14 is connected to the top 13 of the first siphon tube 10, and a pipe 24 is connected to the top 23 of the second siphon tube 20. The pipes 14 and 24 join to form the pipe 30 and branch again to form the pipes 31 and 32. A suction pump 31B is connected to the end of the pipe 31. A silencer 32B is interposed in the middle of the pipe 32, and the end of the pipe 32 is open to the atmosphere. Valves 14A, 31A, 32A are interposed in the pipes 14, 31, 32, respectively.

Next, the procedure for performing backwashing is shown in FIGS.
This will be described with reference to FIG.

Now, it is detected that the filter member 4B is clogged, and the backwashing of the filter member 4B is started from this. At this time, it is assumed that the water level of the filtration pond 4 is X (see FIG. 6).

First, air is fed into the inflow siphon pipe 2 to stop the flow of water from the sewer 1 to the outlet box 3. After a while in this state, the water level of the filtration pond 4 falls and becomes equal to the water level of the filtered water connecting duct 5.

In this state, first, the valve 32A
Is closed and the valves 14A and 31A are opened, and in this state, the suction pump 31B is operated to suction the first and second siphon tubes 10 and 20. Then, as described in the section of the prior art, the first and second siphons 1
Water flows out from the drainage channel 4A to the drainage basin 8A via 0 and 20. The first and second siphon tubes 10,
When a flow of water occurs in 20, the valves 14A and 31A are closed.

As the water continues to flow from the first and second siphon pipes 10 and 20 to the washing drain 8, the water levels of the drainage culvert 4 A and the filtration pond 4 decrease.
When both water levels reach the height of the trough 4C provided in the filter pond 4, a partition wall 4 is provided between the drainage channel 4A and the filter pond 4.
Since there is D, the water level of the filtration pond 4 is maintained at that height,
Only the water level of the drainage ditch 4A decreases. Thereafter, water flows from the filtration pond 4 to the drainage channel 4A via the trough 4C. Thereafter, the water level difference between the drainage channel 4A and the filter pond 4 gradually widens, and when it reaches an equilibrium state, it does not change. The water level of the drainage channel 4A at this time is indicated by a symbol Y in FIG.

Then, at the first flow rate based on the water level difference between the filtered water connecting conduit 5 and the filtering pond 4, a flow of water from the filtered water connecting conduit 5 to the filtering pond 4 occurs. Water passes through the filtering member 4B at a flow rate corresponding to the first flow rate. Thereby, the backwashing of the filtering member 4B is performed.

When the backwash has progressed to some extent and it is near the end,
Open the valve 32A. Then, since air is introduced into the second siphon 20, the second siphon tube 20 no longer serves as a siphon.

In this state, the drainage canal 4A extends from the drainage channel 4A.
The flow of water from the drainage channel 4A to the drainage basin 8A is reduced because the flow of water to the drainage tank 8A is performed only through the first siphon pipe 10. Therefore, the water level of the drainage ditch 4A rises and finally becomes higher than the trough 4C. In this state, since the drainage channel 4A and the filtration reservoir 4 communicate with each other above the trough 4C, the water level of the drainage channel 4A and the water level of the filtration reservoir 4 (FIG. 6)
Y ′) are equal.

In this case, the difference in water level between the filtration pond 4 and the filtered water connecting duct 5 is determined by discharging water from the collecting drain 4A to the drainage box 8A using both the first and second siphon pipes 10, 20. Therefore, the flow velocity of the water flowing into the filtration basin 4 from the filtered water conduit 5 is smaller than that of the first flow velocity.
Flow velocity. The water passes through the filter member 4B at a flow rate corresponding to the second flow rate.

When the backwashing is completed, the valve 14A is opened, and air is introduced into the first siphon pipe 10 so that the first siphon pipe 10 is opened.
The flow of water in the siphon tube 10 may be stopped.

As described above, according to the present embodiment, the backwashing speed is changed by providing two discharge siphon tubes and using both siphon tubes or only one siphon tube as necessary. Can be. This makes it possible to change the backwashing speed of the filter member of the natural equilibrium filter in a very simple manner.

The first and second siphon tubes 10,
Since at least one of the pipes 20 may be an existing siphon pipe, even when remodeling an existing natural equilibrium filtration pond, it is possible to minimize the remodeling of facilities and provide a function of adjusting the backwashing speed.

The first and second siphon tubes 10,
The cross-sectional area of 20 is determined so that the above-mentioned relationship is established between the water level difference between the filtration pond 4 and the filtered water connection duct 5. Therefore, the cross-sectional areas of the first and second siphon tubes 10 and 20 may be the same or different from each other.

Also, the first and second siphon tubes 10,
In addition to 20, one or more siphon tubes (not shown) may be additionally provided. In this way, the backwashing speed can be adjusted in multiple stages.

[Second Embodiment] Next, a second embodiment will be described with reference to FIG. In the second embodiment,
Different from the first embodiment, the backwashing speed is changed using one siphon tube.

FIG. 2 shows an example of the second embodiment. As shown in FIG. 2, a siphon tube 40 is installed in place of the conventional siphon tube 7. Note that the siphon tube 40 may be the existing siphon tube 7 and may be modified to have the following configuration.

As shown in FIG. 2, an air diffuser 41 is provided below the inflow end of the siphon tube 40. A pipe 42 in which a valve 42 </ b> A is interposed is connected to the air diffuser 41, and an air supply pump 43 is provided at an end of the pipe 42. Air is pumped into the diffuser 41 by the air supply pump 43, and air bubbles are continuously mixed into the siphon tube 40 from the diffuser 41. Then, an air layer 48 is formed on the upper part of the siphon tube, and this air layer 48 is formed.
The flow rate of water flowing through the siphon tube 40 can be reduced in accordance with the thickness of the siphon.

On the other hand, above the siphon pipe 40, a pipe 4
4 is connected. The pipe 44 is provided with a pipe 45 provided with a valve 45A and a pipe 46 provided with a valve 46A.
And branch to A suction pump 47 is provided at the end of the pipe 45, and the end of the pipe 46 is open to the atmosphere.

When a flow of water is formed in the siphon tube 40, air is pumped into the diffuser tube 41 by the air supply pump 43, and air bubbles are continuously mixed into the siphon tube 40 from the diffuser tube 41. Let it. Then, the air layer 4 is located above the siphon tube.
8 is formed, and the flow rate of water flowing through the siphon tube 40 can be reduced according to the thickness of the air layer 48.

To return the flow rate of water in the siphon pipe 40 to the original state, the valve 42A is closed, the valve 45A is opened, and the suction pump 47 removes the air layer 48.

Another example of the second embodiment is shown in FIG. As shown in FIG. 3, a siphon tube 50 is installed in place of the conventional siphon tube 7. Note that the siphon tube 50 may be the existing siphon tube 7 and may be modified to have the configuration shown in FIG.

As shown in FIG. 3, a plurality of air bladders 51 are provided at the inflow side end of the siphon tube 50. Each air bag 5
1 is arranged at a position equally dividing the circumference, and the siphon tube 50
One side is fixed to the inner surface of the
It can bulge towards the center of zero.

A pipe 52 is connected to each air bag 51. The pipe 52 branches on the way into a pipe 53 provided with a valve 53A and a pipe 54 provided with a valve 54A. An air supply pump 55 is provided at the end of the pipe 53, and the end of the pipe 54 is open to the atmosphere.

A device for sucking the inside of the siphon tube 50 and a device for introducing air into the siphon tube 50 are connected to the top of the siphon tube 50, but are not shown in FIG.

By appropriately operating the air supply pump 55 and the valves 53A and 54A to adjust the degree of inflation of the air bag 51, the cross-sectional area of the siphon tube 50 can be increased or decreased. The flow rate can be reduced.

FIG. 4 shows still another example of the second embodiment. As shown in FIG. 4, the conventional siphon tube 7 is modified. Of course, a siphon tube may be newly installed.

A variable orifice plate 60 is attached to the inflow end of the siphon tube 7. In this example, a halved base or a pair of base halves 62, 62 connected to each other by bolts 64 is provided with a siphon so that a variable orifice plate can be attached to the end of the flangeless siphon tube 7, in particular. The pipe 7 is attached so as to hold the outer peripheral surface of the inflow side end. The variable orifice plate 60 is fixed to the base halves 62 connected to each other by bolts 63.

The variable orifice plate 60 has a mechanism (not shown in detail) capable of changing the area of the orifice hole 60A, and its opening is controlled by the controller 61. Note that a flow rate may be adjusted by providing a movable valve body in the siphon pipe instead of the variable orifice plate 60 and adjusting the valve opening.

In the description of the second embodiment,
Although the description has been made on the premise that only one siphon tube is used, one or both of the two siphon tubes described in the first embodiment may be provided with the flow rate adjusting function according to the second embodiment. This makes it easy to adjust the backwash speed to another stage.

Further, in the above embodiment, the apparatus for increasing the number of discharge siphon pipes or adjusting the flow rate in the discharge siphon pipes in order to control the flow rate of the water flowing out of the filtration pond has been described. It can also be used to adjust the flow rate of water flowing into the pond. That is, FIG.
Is replaced with the first and second siphon tubes 10 and 20 described in the first embodiment, or the siphon tube 2 shown in FIG. 2 is described in the second embodiment. A flow control device such as a diffuser tube, air bag, variable orifice, etc. may be provided.

Since the water level of the sewer 1 can always be regarded as being constant, either one or both of the two siphon tubes are used as described in the first embodiment, or the water level is described in the second embodiment. As described above, by feeding air into the siphon pipe or inflating the air bag inside the siphon pipe, the flow rate of water flowing from the sewer 1 to the outlet 3 can be adjusted. Can be adjusted.

The filtering speed at a certain point in the natural equilibrium filtration pond may be regarded as the inflow at that point. Therefore, by adjusting the inflow amount of the water to be filtered into the filtration pond 4, the filtration speed can be adjusted.

[0052]

As described above, according to the present invention,
Adjustment of the backwash speed or filtration speed in the natural equilibrium filtration pond can be realized with a simple device configuration.

[Brief description of the drawings]

FIG. 1 is a view for explaining a first embodiment of the present invention, and is a view for explaining a case where two siphon tubes are used for flow rate adjustment.

FIG. 2 is a diagram illustrating an example of a second embodiment of the present invention, and is a diagram illustrating a case where a flow control device including an air diffuser is provided in a siphon tube.

FIG. 3 is a diagram illustrating another example of the second embodiment of the present invention, and is a diagram illustrating a case where a flow control device having an air bag is provided in a siphon tube.

FIG. 4 is a view for explaining still another example of the second embodiment of the present invention, in which a siphon tube is provided with a flow rate adjusting device having a variable orifice plate.

FIG. 5 is a schematic cross-sectional view showing a configuration of a natural equilibrium filtration pond, illustrating a filtration step.

FIG. 6 is a schematic cross-sectional view showing a configuration of a natural equilibrium filtration pond cut along a plane different from FIG. 1, illustrating a backwashing step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sedimentation culvert 2 (Inflow) siphon pipe 3 Exit rise 4 Filtration pond 4A Gutter 4B Filtration member 4C Trough 4E Communication passage 5 Filtration connection culvert 7, 10, 20, 40, 50 (Drainage) Siphon pipe 8 Washing culvert 41 Air diffuser 51 Air bag 60 Variable orifice plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Inbe 1-5-9 Misono-cho, Kodaira-shi, Tokyo (72) Inventor Kawashima Hideko 488 Kitano, Tokorozawa-shi, Saitama (72) Inventor Toshiaki Ueno 2-10-11, Kitadaen, Fussa-shi, Tokyo (72) Inventor Koichi Nagai 2-163-3, Kaminakazato 2-chome, Kita-ku, Tokyo 201 (72) Inventor Hiroaki Horiuchi Tokyo F-term (reference) 3H079 AA26 AA28 BB04 CC12 CC21 DD12 DD22 DD32 DD36 DD39 DD60 4D041 BA03 BB04 BC15 BC17 BD17

Claims (10)

[Claims] 1. A filter tank provided with a filter member and a trough disposed above the filter member, and filtered water communicating with the filter tank through a communication passage provided below the filter member of the filter tank. A culvert, a drainage channel provided adjacent to the filtration reservoir and communicating with the filtration reservoir at a position higher than the trough, and backwash water is discharged from the drainage channel through at least one siphon pipe. A backwashing method for a filtering member of a natural equilibrium filtration pond provided with a washing culvert, comprising:
In the period, the backwash water is discharged at a first flow rate from the drainage culvert to the cleaning drainage culvert through the at least one siphon pipe to adjust the water level of the drainage culvert to be higher than the height of the trough. Then, in a second period before the predetermined time point of the backwashing step, the backwash water is discharged at a second flow rate larger than the first flow rate from the catchment culvert through the at least one siphon pipe. By adjusting the water level of the drainage channel to be lower than the height of the trough, the difference in water level between the filtration basin and the filtered water conduit in the first period is calculated from the difference in water level in the second period. A method for backwashing a natural equilibrium filtration pond, wherein the backwash speed in the first period is made smaller than the backwash speed in the second period. 2. The method according to claim 1, wherein an air bag is provided inside the at least one siphon tube, and a discharge flow rate of the backwash water is adjusted by adjusting a bulge of the air bag. Backwash method. 3. The method according to claim 1, further comprising the step of: providing an air diffuser for feeding air bubbles inside the at least one siphon pipe, and adjusting a discharge flow rate of the backwash water by adjusting an amount of air bubbles. Backwash method as described. 4. A method according to claim 1, wherein a variable orifice or a movable valve body is provided in said at least one siphon pipe, and a discharge flow rate of the backwash water is adjusted by adjusting an opening degree of the orifice or the valve body. Item 7. The backwashing method according to Item 1. 5. A method according to claim 1, wherein a plurality of said at least one siphon pipes are provided, and in said first period, backwash water is supplied from said collecting culvert to said washing culvert at said first flow rate using a first number of siphon pipes. By flowing, the water level of the catchment is adjusted to be higher than the height of the trough, and in the second period, the second flow rate is set at the second flow rate using a second number of siphon pipes larger than the first number. The backwashing method according to claim 1, wherein the backwash water is adjusted to be lower than the height of the trough by flowing backwash water from the catchment channel to the washing drainage channel. 6. A sewer, an outlet box to which water to be filtered is supplied from the sewer through at least one siphon pipe, and a filtration pond to which the water to be filtered is supplied from the outlet box. In the filtering method in the natural equilibrium pond, in a first period from a filtration start time to a predetermined time, the water to be filtered is supplied at a first flow rate from the sewer to the outlet via the at least one siphon pipe. In a second period after the predetermined time point, the water to be filtered is supplied from the sewer to the outlet through the at least one siphon pipe at a second flow rate larger than the first flow rate. Whereby the supply amount of the water to be filtered to the filtration pond in the first period is made smaller than the supply amount of the water to be filtered to the filtration pond in the second period. Filtration method in the natural equilibrium filtration pond. 7. The air supply device according to claim 6, wherein an air bag is provided inside the at least one siphon tube, and the supply amount of the water to be filtered is adjusted by adjusting the inflation of the air bag. Filtration method. 8. A method according to claim 6, wherein an air diffuser for feeding air bubbles is provided inside said at least one siphon tube, and the supply amount of the water to be filtered is adjusted by adjusting the amount of air bubbles. The filtration method described. 9. A method according to claim 1, wherein a variable orifice or a movable valve element is provided in said at least one siphon pipe, and the supply amount of the water to be filtered is adjusted by adjusting the opening of said orifice or valve element. Item 7. The filtration method according to Item 6. 10. A plurality of said at least one siphon pipe is provided, and in the first period, water to be filtered is supplied to the outlet box at the first flow rate using a first number of siphon pipes, In the second period, the filtration target water is supplied to the outlet box at the second flow rate by using a second number of siphon pipes larger than the first number of siphon pipes,
A method according to claim 6.