JPS62237916A - Method for backwashing filter - Google Patents

Abstract

PURPOSE:To effectively backwash with a small quantity of backwashing water by releasing pollutant by backwash of treating water and removing the released contaminated substance by water to be treated. CONSTITUTION:Filter treatment is carried out by actuating a circulating pump 6 and introducing water to be treated into a chamber 4 for water to be treated. In backwashing, the pump 6 is in operation and by raising up pressure in a treating water tank 15 more than pressure in the chamber 4 for water to be treated and backflowing treating water in the treating water tank 15 from a treating water chamber 5 into the chamber 4 for water to be treated, pollutant adhered to a filter medium 3 and piled up. Then, pollutant released from the filter medium 3 and contained in the chamber 4 for water to be treated in a state of suspension is discharged from a line 8 to outside a pressure vessel 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for backwashing a filtration device. More specifically, the present invention relates to a method for backwashing the apparatus, which enables effective backwashing with a small amount of backwash water.

[Conventional technology]

2. Description of the Related Art Apparatuses have been widely used for a long time, in which a filter medium is inserted into a pressure-resistant container to divide it into a water chamber to be treated and a chamber for treated water, and water to be treated is introduced into the chamber to perform filtration.

Porous ceramics, sintered metals, organic membranes, and the like are used as the filter medium. In such a filtration device, by continuing the filtration operation, suspended matter accumulates on the surface and inside of the filter medium, resulting in performance deterioration such as a decrease in the amount of water per 1 tll of filtration and an increase in the filtration pressure difference.

Further, a parallel flow filtration device is known as one of the filtration devices. This parallel flow filtration device allows the water to be treated to flow in a direction parallel to the plane of the filter medium, and has the characteristic that suspended solids are less likely to adhere to the filter medium.

However, even in such a parallel flow filtration device,
If the filtration operation is continued for a long period of time, suspended solids will accumulate, resulting in the same performance deterioration as described above.

If performance decreases due to adhesion or accumulation of turbidity, stop the flow of the water to be treated, and then flow the wash water back from the treated water chamber side to the water quality side to remove the turbidity that has adhered to and accumulated on the filter media. The suspended solids are removed and the suspended solids are discharged out of the thread using washing water.

In this way, the backwashing operation can generally be considered to consist of two processes: a process of peeling off the suspended solids that have adhered or accumulated within the filter medium or the surface of the filter medium, and a process of discharging the peeled suspended solids to the outside of the container. I can do it.

[Problem that the invention seeks to solve]

The conventional backwashing method described above has the following problems.

B. In order to discharge the suspended solids separated from the filter media to the outside of the pressure vessel, it is necessary to backflow a large amount of washing water, generally treated water that has been filtered, and the treated water obtained through filtration must be consumption will be extremely large.

The separated suspended solids are carried out of the pressure vessel by the treated water that passes through the filter medium in the opposite direction, but the flow rate of this water is below the upper limit of the flow rate of the permeated water through the filter medium. Since the flow velocity is low, the separated suspended solids tend to be insufficiently carried out.

[Means for solving problems]

In order to achieve this objective, the backwashing method of the present invention is such that only the turbidity is removed by backflowing the treated water, and the separated turbidity is carried out by the treated water. .

[Effect]

In the present invention, only the removal of suspended matter is performed by backflowing the treated water, so a small amount of backflow flow rate of the treated water is sufficient, and the consumption of the treated water is small. In addition, the exfoliated turbidity is
Since a large amount of water to be treated is introduced by the liquid supply pump and carried out of the pressure vessel, turbidity can be sufficiently discharged.

〔Example〕

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

FIG. 1 is a block diagram showing an apparatus configuration suitable for carrying out the method of the present invention.

In FIG. 1, a filter main body 1 includes a pressure vessel 2 and a filter medium 3 provided to partition the inside of the pressure vessel 2,
A treated water chamber 4 and a treated water chamber 5 are partitioned. A liquid supply line 7 having a circulation pump 6 and a drain line 8 having a flow rate regulating valve 18 are connected to the water chamber 4 to be treated, and these lines 7.8 are each connected to a tank for the water to be treated. ing.

The treated water chamber 5 is connected to treated water take-out lines 9 and 16, and the take-out line 9 is connected to a valve 13 and the take-out line 16.
A tank I5 for storing treated water is provided through a valve 17. This tank 15 is for supplying wash water to the filter main body 1 during backwashing, and is connected to a pressurizing device 14.

In a filtration device having such a configuration, when performing filtration processing, the circulation pump 6 is operated to introduce the water to be treated into the water chamber 4, and excess water to be treated is returned to the tank from the line 8 and filtered in parallel flow. The treated water is transferred from the treated water chamber 5 to the line 9.
A portion is taken out via line 16 and stored in tank 15.

If suspended matter adheres or accumulates on the filter medium 3 by performing this filtration process for a predetermined period of time, backwashing is performed, for example, as follows.

First, the valve 13 is closed while the pump 6 remains in operation.

Moreover, at the same time or before and after this, the pressure inside the treated water tank 15 is increased. In this case, the valve 17 is closed,
The pressure in the treated water tank 15 is increased above the pressure in the treated water chamber 4.

Next, valve 17 is opened. Then, the treated water in the treated water tank 15 flows back from the treated water chamber 5 to the treated water chamber 4. As a result, suspended solids attached and deposited on the filter medium 3 are peeled off.

Since the pump 6 is operated in a steady state and the water to be treated is continuously introduced into the water chamber 4 from the line 7,
The suspended solids separated from the filter medium 3 and contained in a suspended state in the water chamber 4 to be treated are extracted from the pressure vessel 2 through a line 8. After the liquid in the water to be treated chamber 4 has been transported by the water to be treated and has been sufficiently discharged through the line 8, the normal filtration operation can be resumed by opening the valve 13.

In this embodiment, the treated water is taken out through the lines 9 and 16, but it goes without saying that these lines, for example, the line 9 may be provided after the pressurized tank 15.

According to the above procedure, the amount of treated water flowing back from the treated water chamber 5 to the water to be treated chamber 4 is only the amount of suspended matter that is peeled off from the filter medium 3 (which is a very small amount). Since it is the treated water introduced from the line 7 that discharges the suspended solids to the outside of the pressure vessel 2, the suspended solids separated by introducing a sufficient amount of the treated water into the treated water chamber 4 are removed. can be easily and quickly discharged from the container 2.

In a normal filtration device, the opening time of the valve 17 is 5 seconds.
The degree of pressurization in the treated water tank] 5 is preferably
It is preferable that the indicated pressure p4 of the pressure gauge P4 is higher than the indicated pressure p1 of the pressure gauge P1 by about 0.5 kg/cJ,
Appropriate selection should be made taking into consideration the type of filter medium and the properties of suspended solids.

In addition, when backwashing is performed according to the present invention, it is also effective to lower the pressure inside the water chamber 4 to be treated by opening the valve 18 provided in the line 8 to a larger degree than during normal filtration operation. be. In this way, sufficient backwashing can be performed even if the pressure of the backwash water is lowered.

Furthermore, in the present invention, conventional backwashing methods may be used in combination.

Examples and comparative examples of backwashing in a parallel flow filtration device using a filter medium made of a capillary type organic membrane will be described below.

Water flow conditions during filtration treatment are as follows.

Treated water: A liquid containing fine particles of Fe(OH)s at a ratio of 1 g/l.

Water pressure to be treated in the filtration process 2 kg/cJ Amount of filtrated water at the initial stage of water flow: 14.7 m'/m''-day Example After the filtrated water flow rate decreased to 4.3 m'/m''-day, the valve 13 At the same time, the pressurizing means 14 is activated to increase the pressure inside the treated water tank 15 to 2.5 kg/-.

Next, the valve 17 is opened for 5 seconds to cause the treated water to flow backward from the treated water chamber 5 to the treated water chamber 4. The separated suspended solids were transported to the water to be treated and discharged to the outside of the container 2.

As a result, the amount of filtrated water recovered to 14.6 m'/rn'·day.

Comparative Example Instead of the above-mentioned backwashing method, after the pump 6 was stopped, the filter medium 3 was backwashed at a backwash pressure of 2.5 kg/ci and a backwash time of 10 seconds. As a result, the amount of permeated water was restored to 12.5 m'/day.

In addition, in the example, the amount of backwash water is 1rr of membrane area. In comparison, the comparative example required 3oβ.

As is clear from the above Examples and Comparative Examples, it is clear that according to the present invention, the amount of filtrate can be restored to a significantly high level by simply backflowing a very small amount of treated water.

〔Effect of the invention〕

As detailed above, according to the backwashing method of the present invention, only a very small amount of treated water is consumed for backwashing, and there is no waste in consumption of treated water. Furthermore, since the separated suspended solids are discharged using the water to be treated that is constantly being passed through, the suspended solids can be efficiently discharged in an extremely short period of time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus suitable for carrying out the method of the present invention. ■...filtration device body, 2...pressure vessel, 3...
...filter medium, 4...treated water chamber, 5...
Treated water chamber, 6... Pump, 7... Liquid supply line, 8... Drainage line, 9... Treated water take-out line, 14... Pressurizing means, 15... Processing tank, 13.14.17.18... Valve.

Claims (2)

[Claims] (1) A filter material is inserted into a pressure-resistant container to divide it into a treated water chamber and a treated water chamber, and the treated water chamber is connected to a liquid supply line with a liquid supply pump and a waste liquid line, and the treated water When backwashing a filtration device in which a treated water take-out line and a wash water tank equipped with pressurizing means are connected to the chamber, the liquid supply pump installed in the liquid supply line must be stopped. backwashing of a filtration device, characterized in that backwashing is performed by supplying wash water pressurized to a level higher than that of the water to be treated in the wash water tank to the treated water chamber while the water to be treated continues to flow through the water; Method. (2) The method for backwashing a filtration device according to claim 1, wherein the filtration device is a parallel flow filtration device.