JP2820384B2 - Method of cleaning filter media for water treatment / filtration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for washing a filter medium in a water treatment / filtration apparatus filled with a compressible floating filter medium.

[0002]

2. Description of the Related Art In general, a water treatment apparatus is provided with a water treatment facility for removing pollutants by microorganisms grown on the surface of a filter medium filled in a treatment tank and a filter medium for removing suspended substances in water to be treated. There is a filtration device. If these water treatment / filtration apparatuses are used for a long time, clogging occurs due to suspended substances trapped in the gaps between the filter media and bacteria growing on the surface of the filter media, and the treatment efficiency is reduced. Therefore, it is necessary to restore the treatment efficiency by washing / removing the suspended substances and the proliferating cells trapped in the gaps between the filter media at appropriate time intervals. The filter medium is washed at the earlier time when the suspended substance in the treated water reaches a certain concentration or more or when the pressure loss reaches a predetermined value or more due to clogging.
Typically, filter media cleaning is performed systematically before reaching this point.

[0003] The washing of the filter medium in this water treatment / filtration apparatus is performed by blowing washing air from below into the filter medium layer to stir the filter medium, to separate trapped suspended substances and cells, and to wash the washing water in a normal manner. It is performed by flowing suspended substances and cells separated in the same or opposite direction to the flow of water to the outside of the treatment tank. From this washing operation, the water treatment and filtration equipment
, That is, the operation of supplying water into the processing tank before shifting to the operation processing operation, thereby performing the final washing of the filter medium. At this time, in the filter medium washing method, in the water supply operation of step (8) in FIG. 1, a larger amount of water is supplied into the conventional treatment tank than the amount of water during the operation treatment operation , and the supply is continued even after the water is full.
A method has been adopted in which the water supply to the treatment tank and the washing of the filter medium layer are completed in a short time. After the cleaning is finished, the operation processing Misao
It is shifting to work .

[0004]

SUMMARY OF THE INVENTION According to the present invention, in a water treatment / filtration device in which a filter medium is filled in a treatment tank, water is supplied into the treatment tank before the filter medium is shifted from a washing operation to a normal treatment operation. It provides an improved method.

[0005]

The present invention for solving the above problems SUMMARY OF THE INVENTION fills the floating filter media compressibility, have a top outflow preventing section for outflow prevention to the top of filtrate material, after stopping the operation,
Partial drainage / air cleaning / drainage / water supply when cleaning filter media
・ Perform washing operation of the filter media consisting of air washing at least once,
Water treatment and filtration of water treatment / filtration equipment for washing and passing to operation processing
In the material washing method , (1) operation processing
Supply a larger amount of cleaning water than the amount of water treated during operation, and
The upper part of the filter medium layer that floats the feed reaches the upper outflow prevention means.
Stop immediately before or immediately after,
Continue flushing with water flow. (2) Same as during operation
When supplying the same amount of treated water, remove air from the bottom of the filter media layer.
Stir the filter media by supplying it for a fixed time, or (3)
After stopping the supply of a large amount of cleaning water during water cleaning,
Before supplying with the same amount of treated water as during the
The air is supplied for a certain period of time to stir the filter media.
The method includes a method of washing a filter medium. The following theory
In the following, what is referred to as "normal"
Work ".

Hereinafter, the present invention will be described in detail.

The present invention provides a method for cleaning a floating filter medium which is effectively used in a water treatment / filtration apparatus using a floating filter medium compressed by pressure loss of a filter medium layer. The floating filter medium used here is a non-crystalline resin obtained by copolymerizing ethylene, propylene or the like with another monomer, or a resin obtained by foaming a resin obtained by mixing polyethylene or polypropylene. Is mentioned.

Next, the cleaning method of the present invention will be described with reference to the drawings.

FIG. 1 shows the steps of a series of filter medium washing operations. The upward-flow filtration device was filled with 1 m of a compressible floating filter medium, and a filtration operation was performed for a certain period of time. Thereafter, a series of filter medium washing operations in steps (1) to (7) shown in FIG. 1 are performed, and in step (8), water is supplied from the washing water pump at a normal flow rate of 3 times.
Started with double volume. When the upper part of the floating filter medium layer reaches the position of the upper outflow prevention means, the supply of water is stopped, and the water to be treated flows with a normal amount of water. The treated water at this outlet is returned to the receiving tank for treated water again. This operation is continued while observing the state of recovery of the quality of the treated water, and then the treated water is switched to normal water supply. Also, immediately before or immediately after the upper part of the filter medium layer reaches the upper outflow prevention means, while supplying water or while stopping, air is supplied from the lower part of the filter medium layer for a certain time to stir the filter medium layer. Then, water is supplied again, and the treated water at the outlet is returned to the receiving water receiving tank. This operation is continued while observing the state of recovery of the quality of the treated water, and then the treated water is switched to normal water supply.

In the present invention, means for preventing the filter medium from flowing out of the treatment tank from the upper part include a net, a bar screen or a perforated plate having a high strength irrespective of the material. Any structure may be used as long as it has a structure that allows the passage of the same without any trouble. Further, these nets, bar screens, perforated plates, and the like can be used in combination.

In the present invention, the present invention can be used in a biological treatment apparatus for an aerobic biofilm treatment method in which aeration air is blown into wastewater. It can also be used for anaerobic biofilm treatment without blowing air.
It can also be used for a filtration device for removing fine suspended substances.

In the present invention, treated water or water to be treated can be used as the water and cleaning water supplied to the treatment tank before shifting from the washing operation to the ordinary treatment operation.

[0013] In the present invention, the washing water supplied in a larger amount than the usual amount of water is 1.5 to 20 times the normal flow rate.
It is supplied in an amount of 2 times, preferably 2 to 10 times. The cleaning water is supplied in the same direction as the flow of the normal water to be treated or in the opposite direction.

In the present invention, the filter medium layer is stirred by supplying air from the lower part of the filter medium layer for a certain period of time, but the time is not particularly limited, and the effect of sufficiently washing the filter medium layer and making the filter layer uniform can be sufficiently obtained. May be appropriately determined as described above. Normally,
About 0.5 to 5 minutes is sufficient.

In the present invention, the start / stop of water supply to the processing tank, the change of flow rate, the start of air agitation, the duration of agitation, etc. are detected by measuring the water surface position in the processing tank by a measuring instrument or automatically by a time setting device. Can be done In the present invention, the first treated water at the outlet of the treated tank is returned to the receiving tank for treated water again, and then switched to normal water supply.This operation measures the quality of the treated water and automatically or automatically sets the time. This can be done by operating an automatic valve.

[0016]

According to the filter medium washing method of the present invention, in the water supply operation of the step (8) in FIG. 1, conventionally, a larger amount of water is supplied into the treatment tank than the usual amount of water, and the supply is continued as it is after the water is full. In the conventional method, water is supplied to the filter and the washing of the filter medium layer is completed in a short time.In the conventional method, when an elastic filter medium is used, the filter medium is pressed against the upper outflow prevention means and compressed, causing a rapid drop in pressure loss. May cause troubles in the subsequent treatment operation.However, by stopping water supply with a large amount of water before the filter medium is pressed down by the upper outflow prevention means, compression of the filter medium can be prevented, and consequently pressure loss At this time, air is supplied from the lower part of the filter medium layer to agitate the filter medium layer to make the thickness of the layer uniform, thereby preventing a partial decrease in treatment efficiency. Can

[0017]

The present invention will be described below in detail with reference to examples.

Example 1 An upflow filter was filled with 1 m of a compressible floating filter medium, and 4 mg of a sulfuric acid band (in terms of Al ₂ O ₃ ) was used as a flocculant in pond water containing 20 mg / l of a suspended substance such as algae. / L was added and a filtration operation was performed for a certain period of time. Thereafter, a series of filter medium washing operations in steps (1) to (7) shown in FIG. 1 are performed, and in step (8), water is supplied from the washing water pump at a normal flow rate of 3 times.
Started with double volume. When the upper part of the floating filter medium layer reached the position of the upper outflow prevention means, the water supply was stopped, the water to be treated was flowed with a normal amount of water, and the treated water at the outlet was returned to the receiving tank of the treated water again. This operation was continued for 10 minutes, after which the treated water was switched to normal water supply. Table 1 shows the operating conditions at this time.

Example 2 The same apparatus as in Example 1 was used, and the steps (1) to (7) shown in FIG.
Was performed, and in step (8), water supply was started from the washing water pump at an amount three times the normal flow rate.
Water supply was stopped when the upper part of the floating filter medium layer reached the position of the upper outflow prevention means, air was supplied from the lower part, and the filter medium layer was stirred to make the thickness of the layer uniform. Thereafter, the water to be treated was flowed with a normal amount of water, and the treated water at the outlet was returned to the receiving tank for the treated water again. This operation was continued for 10 minutes, after which the treated water was switched to normal water supply. Table 1 shows the operating conditions at this time.

Comparative Example Using the same apparatus as in Example 1, steps (1) to (7) shown in FIG.
Was performed, and in step (8), water supply was started from the washing water pump at an amount three times the normal flow rate.
Water supply was continued even after the upper part of the floating filter medium layer reached the position of the upper outflow prevention means. The treated water at the outlet at this time was returned to the receiving tank of the treated water again. This operation was continued for 3 minutes, after which the treated water was switched to normal water supply. Table 1 shows the operating conditions at this time.

[0021]

[Table 1] Removal rate duration: Time required for the SS concentration (suspension concentration) in treated water to reach zero to 1 mg / l. Predetermined pressure drop reaching time: Time when the pressure drop of the filter medium layer reaches 5 m water column.

The filter medium is washed when the removal rate of the suspended substances reaches 1 mg / l or when the pressure loss reaches 5 m water column, whichever comes earlier.

[0023]

According to the filter medium washing method of the present invention, it is possible to prevent the filter medium layer from being pressed more than necessary to the upper outflow prevention means, so that an excessive increase in pressure loss due to the filter medium can be prevented, and the processing operation time can be reduced. Can be extended. In addition, the uniformity of the filter medium layer can prevent a partial decrease in efficiency. Therefore, the effect of reducing the frequency of washing the filter medium and reducing the amount of washing wastewater can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a filter material washing step of the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-57210 (JP, A) JP-A-8-10523 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01D 24/00-24/48 B01D 29/00-29/96

Claims (3)

(57) [Claims] 1. A filled floating filter media compressibility, have a top outflow preventing section for outflow prevention to the top of filtrate material, operating
After the stop, when cleaning the filter media, partially drainage, air cleaning, drainage
Washing operation of filter media consisting of water, water supply and air washing at least once
Water treatment / filtration to be carried out, washing with water, and moving to operation treatment operation
In the filter medium washing method of the apparatus, in the above-mentioned water passing washing, a larger amount of water than the amount of water treated during the operation treatment operation.
A filter medium washing method in which washing water is supplied, and immediately before or immediately after the upper portion of the filter medium layer that floats the supply reaches the upper outflow prevention means, and then the water washing is continued with the amount of water at the time of the operation processing operation . 2. An operation processing operation at the time of said water washing.
When supplying with the same amount of water as at the time, air is
Claiming that the filter medium is stirred for a certain period of time.
Item 4. The method for cleaning a filter medium according to Item 1 . 3. A supply of a large amount of washing water at the time of said water washing.
Before stopping and supplying the same amount of water as during the operation processing operation
Air is supplied from the bottom of the filter medium layer for a certain time to stir the filter medium
2. The method for cleaning a filter medium according to claim 1, wherein