JPH1147511A - Filtration pond and method for operation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve water recovery ratio in a water purification facility by reusing discharged water and to keep the turbidity of water at the outlet of a filtration pond 0.1 degree or lower by smoothly switching the filtration operation from water discharging operation. SOLUTION: On completion of the back washing operation of a filtration pond A, a water discharge valve 6a is opened and a water discharge pump 9 is started and while the turbidity of the discharged water is measured by a turbidity meter 11, the flow rate of the water discharge pump 9 is gradually increased and when the turbidity of the discharged water is lowered to a set turbidity or lower and the filtration speed reaches a set speed, the water discharge operation is completed and then a flow out valve 3a is opened and the water discharge valve 6a is closed to shift to the normal filtration operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter pond and a method for operating the filter, and more particularly, to a drainage operation in a rapid filter pond provided in a water purification plant, and can be applied to both existing and new filters. The present invention relates to a filter pond and its operation method.

[0002]

2. Description of the Related Art In water purification treatment at a water purification plant, as a measure against Cryptosporidium, the turbidity of water at the outlet of a filtration pond is constantly monitored, and the turbidity of the outlet of the filtration pond is reduced to 0.1. Degree below. Therefore, after performing operations such as washing of the filtration pond, since the filtration function is not developed, water is drained until the turbidity at the outlet of the filtration pond becomes 0.1 ° or less. However, this draining operation not only takes about 30 minutes, but also wastes a large amount of water during this time. In addition, when the filtration speed is rapidly increased when the operation is switched from the waste water operation to the normal filtration operation, the turbidity also increases, so that it is difficult to maintain the turbidity at the outlet of the filtration tank at 0.1 degrees or less. .

[0003] Accordingly, the present invention is to improve the water recovery rate in a water purification plant by reusing waste water, to achieve effective use of water resources, and to smoothly switch from waste water operation to filtration operation. And the turbidity of the water at the outlet of the filtration pond is reduced to 0.
It is an object of the present invention to provide a filter pond that can be reliably maintained at a temperature of once or less and a method of operating the filter.

[0004]

In order to achieve the above object, a filtration pond according to the present invention comprises a raw culvert, a plurality of filtration ponds connected to the raw culvert via respective inflow valves, and Merges the water purifier connected via the outflow valve, each drain valve discharging backwash drainage from each filter pond, the drainage pipe connected to each filter pond via the drainage valve, and each drainage pipe It is characterized by comprising a collecting drain pipe for returning the waste water to the raw sewer, and a drain pump, a flow meter and a turbidity meter provided in the collecting drain pipe.

[0005] The method of operating a filter pond of the present invention is a method of operating the filter pond having the above-described structure, particularly an operation method of drainage operation. Open and operate the wastewater pump, gradually increase the flow rate of the wastewater pump while measuring the turbidity of the wastewater with the turbidity meter, the turbidity of the wastewater becomes less than the set turbidity, and the filtration speed is set. When the speed reaches the speed, the drainage operation is terminated, the outflow valve is opened, the drainage valve is closed, and a transition is made to a normal filtration operation, and further, at the start of the drainage operation, the drainage operation is performed. When the turbidity exceeds a predetermined value, the wastewater is discharged to a wastewater storage tank via a wastewater discharge pipe branched from the entrance of the raw sewer without returning the wastewater from the collective drainage pipe to the raw sewer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system diagram showing one embodiment of a filter pond according to the present invention, which comprises four filter ponds A, B, C and D. The filter ponds are raw water culverts 1, filter ponds A, B, C, and D connected to the raw water culverts 1 through inlet valves 2a, 2b, 2c, and 2d, respectively.
Water purification tank 4 connected to C and D through outflow valves 3a, 3b, 3c and 3d, respectively, and drain valves 5a, 5b and 5b for discharging backwash wastewater from each of filtration ponds A, B, C and D. 5
c, 5d, and a drainage pipe 7a connected to each of the filtration ponds A, B, C, D via drainage valves 6a, 6b, 6c, 6d, respectively.
7b, 7c, 7d and each drainage pipe 7a, 7b, 7c, 7d
And a collecting drain pipe 8 for returning the waste water to the raw culvert 1;
A water pump 9, a water flow meter 10, and a turbidity meter 11 are provided in the collecting water pipe 8.

As the outflow valves 3a, 3b, 3c, 3d, flow regulating valves which are opened and closed by a motor M are used, and filtration flow meters 12a, 12b, 12 provided in series with the respective valves.
Each of the filtration ponds A, B, C, and D is adjusted by c and 12d so as to have an appropriate amount of filtered water. Also, a pump that can adjust the flow rate by controlling the number of rotations is used as the water drainage pump 9, and the flow rate is controlled by the water drainage flow meter 10 to an appropriate flow rate.

Further, the collecting drainage pipe 8 needs a sampling pipe 13 and a sampling valve 14 connected to a particle measuring instrument (not shown) for measuring fine particles in the wastewater, and requires drainage of the collecting drainage pipe 8. Washing drainage storage tank (not shown)
Drainage pipe 15 for discharging water to the drain and this wastewater discharge pipe 1
Switching valves 16 and 17 for switching the discharge of waste water to
And an air gap 18 for preventing the raw water (unfiltered water) from flowing back to the filtered water side.

In a normal filtration operation, raw water is supplied from raw culvert 1 to filtration ponds A to D through inlet valves 2a to 2d.
The purified water filtered in each of the filtration ponds A to D is supplied to the filtration flow meter 1
Outflow valves 3a to 3d whose flow rates are controlled by 2a to 12d
And flows into the water purification tank 4.

[0010] The backwashing of the filtration basin is performed sequentially for each filtration basin. For example, after the backwashing and the drainage operation of the filtration basin A are completed, the filtration basin B starts the backwashing and the drainage operation. It is set so that the backwash operation of the filtration ponds C and D is performed sequentially.

Here, a method of operating the filter pond from the state in which the filter pond A has entered the backwashing operation from the filter operation will be described.
First, the inflow valve 2a is closed to shut off the inflow of raw water. At this time, the outflow valve 3a is open, the drain valve 5a and the drain valve 6a are closed, and the drain pump 9 is stopped. The backwashing operation varies depending on the type of the filtration pond. Usually, the outflow valve 3a is closed and the drainage valve 5a is opened to discharge the water (washing wastewater) in the filtration pond A to the washing drainage storage tank. This is performed by flowing back the purified water in the filter A as the washing water.

When the backwashing operation is completed, the drainage operation is started, the outflow valve 3a and the drainage valve 5a are closed, the inflow valve 2a and the drainage valve 6a are opened, and the drainage pump 9 is started. At this time, the water is discarded from the start of the operation by switching the switching valve 16
Although it may be returned to the raw culvert 1 via 8, when the turbidity of the waste water is high, for example, when the turbidity exceeds 1 degree,
The switching valve 16 of the collecting drain pipe 8 may be closed, and the switching valve 17 of the drain pipe 15 may be opened to discharge the waste water to the washing and drainage storage tank.

The rotation speed of the water drainage pump 9 is set to a low speed at the start of operation, the rotation speed is gradually increased to increase the amount of water drainage, and the filtration speed at the time of water drainage is gradually increased. Set the same filtration speed as the filtration speed. This waste water pump 9
Can be performed according to the turbidity measured by the turbidity meter 11, and when the turbidity is high, the speed may be set to a low speed, and the speed may be increased as the turbidity decreases.

When the turbidity measured by the turbidimeter 11 or the value measured by the fine particle meter becomes a preset value, and the filtration speed becomes the same as the filtration speed in the ordinary filtration operation, the outflow valve 3a Is opened, the drainage pump 9 is stopped, the drainage valve 6a is closed, and the operation shifts from the drainage operation to the filtration operation. Next, backwashing and drainage operations in other filtration ponds are performed sequentially in the same manner.

By performing the water draining operation as described above, the water recovery rate at the water purification plant can be improved, and the turbidity of the filtered water can be reliably maintained at 0.1 degrees or less.
That is, in the drainage operation, the drainage water that was conventionally discharged to the cleaning drainage storage tank is returned to the raw culvert 1 by the drainage pump 9, and the water with high turbidity is washed and drained from the drainage discharge pipe 15. Even if it is discharged to a storage tank, the amount is extremely small compared to the conventional one, and most of the inflowing raw water can be supplied as purified water only by discharging the washing wastewater and a small amount of wastewater during the backwashing operation. This is effective for effective use of water resources and measures against drought.

In addition, since the drainage operation is switched from the drainage operation to the filtration operation in a state where the filtration speed at the time of the water drainage is equal to the filtration speed at the time of the filtration operation, the turbidity due to the sudden change of the filtration speed is reduced. The rise can be prevented, and the turbidity at the outlet of the filtration pond can be reliably maintained at 0.1 ° or less.

Furthermore, since the turbidity meter 11 can be installed in the collecting drain pipe 8 to perform necessary and sufficient turbidity management, there is no need to provide a turbidity meter in the drain pipe from each filtration pond.

The type of the filtration basin is arbitrary, and the inflow valve and the like are not limited to so-called valves, and other inflow and outflow devices such as siphons and empty traps can be used as appropriate. It is not limited to the above embodiment.

[0019]

As described above, according to the present invention,
The water recovery rate at the water purification plant can be improved, and the turbidity can be reliably maintained at a predetermined value or less, for example, 0.1 degrees or less.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of a filtration pond of the present invention.

[Explanation of symbols]

A, B, C, D ... filtration pond, 1 ... raw culvert, 2a, 2b, 2
c, 2d ... inflow valves, 3a, 3b, 3c, 3d ... outflow valves,
4 ... water purifier, 5a, 5b, 5c, 5d ... drain valve, 6a,
6b, 6c, 6d ... drain valve, 7a, 7b, 7c, 7d ...
Drainage pipes, 8: Drainage pipes, 9: Drainage pumps, 10: Drainage flow meters, 11: Turbidity meters, 12a, 12b, 12c, 12
d: Filtration flow meter, 13: sampling pipe, 14: sampling valve, 15: waste water discharge pipe, 16, 17, switching valve, 1
8. Air gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/00 (72) Inventor Naokatsu Tanabe 1-3-3 Kyobashi, Chuo-ku, Tokyo Inside Maezawa Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A raw water culvert, a plurality of filtration ponds connected to the raw culvert via respective inflow valves, a water purification ponds connected to the filtration ponds via respective outflow valves, and backwashing from each of the filtration ponds. A drain valve connected to each of the drainage valves for discharging drain water, each filtration pond through a drain valve, a drain pipe connected to each drain pipe to return drain water to the raw water conduit, A filtration pond comprising a waste water pump, a flow meter and a turbidity meter provided in a water pipe. 2. The method for operating a filter pond according to claim 1, wherein after the backwash operation of the filter pond, the water drain valve is opened to operate a water drain pump, and the water is drained by the turbidity meter. While measuring the turbidity, gradually increase the flow rate of the drainage pump, the turbidity of the wastewater becomes equal to or less than the set turbidity, and when the filtration speed reaches the set speed, the drainage operation is completed, and the outflow valve is closed. A method for operating a filtration pond, comprising opening and closing a drain valve to shift to normal filtration operation. 3. When the turbidity of the waste water exceeds a predetermined value at the start of the waste water operation, the waste water discharged from the front of the raw sewer entrance is returned without returning the waste water from the collecting sewer pipe to the raw sewer. The method for operating a filtration pond according to claim 2, wherein the water is discharged to a wastewater storage tank via a pipe.