JPS6295107A - Method and device for cleaning filter basin - Google Patents

Abstract

PURPOSE:To reduce the amt. of a fluid necessary for cleaning and the power consumption and to save the energy by applying several agitations for agitating the part in the vicinity of the surface of a filter medium bed before the filter medium bed is backwashed and the surface is cleaned. CONSTITUTION:The raw water is supplied from a raw water supply pipe 2 and filtered by the filter medium bed 3. The filtered water is discharged from a filtered water discharge pipe 5. The contaminants are collected by the filtered water discharge pipe 5. The contaminants are collected by the filter medium bed 3 and the pressure drop of the filter medium bed 3 is progressively increased. When the pressure drop exceeds a set pressure drop, whether the duration up to that time exceeds the set duration or not is judged. When the duration exceeds the set duration, the part in the vicinity of the surface of the filter medium bed 3 is agitated by a surface vicinity agitator 10, the clogging of the filter medium bed 3 is temporarily eliminated, and filtration is resumed. When the duration does not exceed the set duration, cleaning wherein backwashing and surface washing are simultaneously carried out, is applied, and filtration is continued.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a cleaning method and apparatus for effectively cleaning a filter layer in a filter pond for clarifying and filtering wastewater.

``Prior art'' Various types of filters have been known for filtering wastewater (hereinafter referred to as raw water), but among them, gravity-type granular activated carbon filters have been used as filters for urban water supplies, etc. Figure 6 shows this activated carbon filtration pond 1. Raw water sent from a raw water supply pipe 2 flows down by gravity through a filter layer 3 consisting of a layer of granular activated carbon, and during this time, pollutants in the raw water are removed. At the same time as being captured by the filter medium layer 3, the raw water that has passed through the channel group formed by these captured substances and the filter medium is taken out of the system as filtered water from the lower water collection device 4 via the filtered ice removal pipe 5. ing.

In addition, if the contaminants in the filter layer 3 increase due to filtration and the pressure loss increases, the button will cause water to be jetted out from the lower water collection device 4 through the backwash pipe (backwash device 6) and Layer 3 is washed in a floating state. At the same time, surface flow #f (
Pressure water is injected from the surface cleaning device (7) to increase the collision friction between the filter media and enhance the cleaning effect.

In addition, in the figure, 8 is a trough, 9 is a cleaning drain pipe, 2 a,
5a, 6a.

7a and 9a are, in order, a raw water valve, a filtered water valve, a backwash valve, a surface washing valve, and a washing drain valve.

"Problems to be Solved by the Invention" However, in the filtration basin 1, backwashing and surface washing must be performed quite frequently in order to maintain good filtration water quality, and as a result, the amount of water required for washing is reduced. The problem was that the power required increased and operating costs increased.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a method and apparatus for cleaning a filtration basin that saves energy by extending the interval between backwashing and surface cleaning.

In order to achieve the above object, the method of the present invention includes stirring the near surface portion of the filter layer before proceeding to the cleaning step of backwashing the filter layer and cleaning the surface. The device of the present invention is designed to carry out the near-surface stirring step an appropriate number of times.
It is composed of a backwashing device for backwashing the filtering medium layer, a surface cleaning device for surface washing the filtering medium layer, and a near-surface agitation device for stirring the portion near the surface of the filtering medium layer.

"Function" In the present invention, when the filter layer becomes clogged, it is backwashed and the surface is washed at the same time as in the conventional method, but before the cleaning is carried out, only the portion near the surface of the filter layer is stirred by a near-surface stirring device. Then, the blockage of the filter medium is temporarily cleared and the time until the above-mentioned backwashing and surface cleaning is extended.

``Example'' Figures 1 to 6 show an example of the device of the present invention, and parts having the same basic structure as the conventional example are given the same reference numerals as the conventional example and will be explained. omitted.

In the figure, lO is a stirring pipe (near surface stirring device) connected to a pressure water supply pipe (not shown). This stirring tube 10 is equipped with a stirring valve 11 at a predetermined position located outside the filter basin 1, and inside the filter basin 1, the depth h from the surface of the inner part of the filter medium layer 3 is 10. It is arranged horizontally at a height of ~50 cm, and branch pipes 10b are connected to the buried pipe section 101L located in the inner part of the filter medium layer 3 at appropriate locations in the longitudinal direction. . Then, the terminal ends of the buried pipe portion 10a and each branch pipe 10b are closed, and on the upper side of each pipe wall, the pipes are distributed at an angle of, for example, 45 degrees to the left and right of the pipe with the axis of the pipe as the center. A plurality of nozzles 10c facing upward are provided at a predetermined pitch in the longitudinal direction of the tube.

Thus, in the above apparatus, backwashing and surface cleaning of the filter layer 3 are carried out by the backwash tube 6 and the surface cleaning tube 7, as in the conventional method, while the portion near the surface of the filter layer 3 is stirred by the stirring tube 1o. That is, the stirring valve 11 is opened and pressurized water is spouted from the nozzle 10c of the stirring tube 10. Then, the pressurized water is ejected upward from the inside of the filter layer 3, agitates the area near the surface of the filter layer 3, causes the filter media to collide and rub against each other, dispersing the pollutants and removing them under pressure. Since blockage in the filter medium layer 3 is likely to occur in the vicinity of the surface of the filter medium layer 30, the blockage in the filter medium layer 3 can be effectively eliminated by stirring and cleaning only that area. The amount of water and power consumption is much lower than in backwashing and surface cleaning.

Next, an embodiment of the method of the present invention will be described based on FIG.

First, raw water is supplied through the raw water supply pipe 2 and filtered through the filter medium layer 3 as usual, and filtered water is continuously taken out from the Il filter water take-out pipe 5. Then, the pollutants in the raw water are captured by the filter layer 3, and this increases, and the pressure loss P in the filter layer 3 gradually increases. This pressure loss P is the set pressure loss P
If there are no drops, continue filtration, but the pressure loss P
When the pressure loss becomes equal to or greater than the set pressure loss PB, it is determined whether the required time t up to that point exceeds the set required time t8. If the required time t exceeds the set required time t, the near-surface portion of the filter layer 3 is stirred by the near-surface stirring device [10, thereby temporarily eliminating the blockage of the filter layer 3 and starting the filtration again. Start. Further, if the required time t does not exceed the set required time t 2 , the process moves to a cleaning step in which backwashing and surface cleaning are performed simultaneously, the blockage of the filter medium layer 3 is completely eliminated, and filtration is continued.

That is, in the above method, the pressure loss P is equal to the set pressure loss P
Even if it exceeds 8, if it is exceeded at a stage later than the set required time t, it is judged that the degree of blockage of the filter medium layer 3 is still minor, and the blockage is temporarily removed by moving to the near-surface stirring process. If the problem is resolved and filtration continues, and if the pressure loss P exceeds the set pressure loss P8 within the set required time, it is determined that the degree of blockage in the filter medium layer 3 has progressed considerably. Then move on to the cleaning process using full-scale backwashing and surface cleaning.

Here, since blockage in the filter medium layer 3 usually occurs from a portion near the surface of the filter medium layer 3, it is extremely effective to perform stirring near the surface at a stage when the degree of blockage is low. Therefore, if near-surface agitation is performed before moving on to the full-scale cleaning process as described above, it is actually possible to replace a significant portion of the number of full-scale cleaning processes with this near-surface agitation. be.

Therefore, the number of times of the above-mentioned cleaning process, which consumes a large amount of water and power, is reduced, and in its place, the stirring process near the surface, which consumes very little water and power, is performed, so the overall amount of water and power consumed are reduced compared to those of the previous one. This is significantly reduced compared to .

Further, FIG. 5 shows another embodiment of the method of the present invention, in which the pressure loss P is the set pressure loss Pa1
When the above is reached, the near-surface stirring step is started, and this is repeated until the number of times N of this near-surface stirring step reaches the set number Ns. Then, only when the set number of times N8 has been reached does the cleaning process consisting of backflow cleaning and surface cleaning proceed. With this method, as in the case described above, the number of full-scale cleaning steps can be reduced and energy can be saved.

Incidentally, in the above description, the stirring tube 10 is provided with a plurality of nozzles 10c, but their positions are not limited to the illustrated positions, and nozzle holes may be formed in place of the nozzles 10c. In addition, instead of jetting out pressurized water through the stirring tube 10, compressed air may be jetted out, and the same applies to backwashing and surface cleaning.Furthermore, in the above embodiment, granular Although we have described a filter using activated carbon, it is a matter of course that other types of filter media, such as sand, may also be used.

"Effects of the Invention" As explained above, the present invention performs backflow cleaning and surface cleaning at the stage when the filter media layer is clogged. By stirring only the area near the surface of the filter layer, this temporarily relieves the blockage of the filter layer and extends the time required for backwashing and surface cleaning, reducing the amount of fluid and power consumption required for cleaning. This has the effect of reducing energy consumption and saving energy.

[Brief explanation of drawings]

1 to 3 show an embodiment of the apparatus of the present invention, in which FIG. 1 is an overall schematic diagram, FIG. 2 is a schematic sectional view of the main part, and FIG. 3 is an arrow ff-1 in FIG. 2. 4 is a flowchart showing one embodiment of the method of the present invention, FIG. 5 is a flowchart showing another embodiment, and FIG. 6 is an overall schematic diagram showing a conventional example. . 3... Filter media layer, 6... Backflow cleaning tube (backflow cleaning device surface, 7... Surface cleaning tube (surface cleaning device), 10... Stirring tube (near surface stirring device).

Claims (2)

[Claims] (1) A method for cleaning a filtration basin, characterized by carrying out a near-surface agitation step for stirring the near-surface portion of the filter layer an appropriate number of times before proceeding to a cleaning step for backwashing the filter layer and surface cleaning. . (2) Cleaning of a filter basin characterized by comprising a backwashing device for backwashing the filtering medium layer, a surface cleaning device for surface washing the filtering medium layer, and a near-surface agitation device for stirring the portion near the surface of the filtering medium layer. Device.