JPS6154214A - Method of washing filter - Google Patents

Abstract

PURPOSE:To economically wash a filter without causing any trouble in blocking meshes of a strainer by reutilizing as washing water, the waste water obtd. by usual washing in the following step of back washing of the filter. CONSTITUTION:A washing step is commenced when resistance passing through the filter 1 increases due to blocking of the meshes. After stopping the operation, the waste water stored in a tank 3' in the preceding usual washing step is led to the filter 1 to back wash the filter 2 via a pump 14 and an inlet pipe 15 for the waste water using to back wash the filter member 2 whereby a solid deposited in the filter member 2 is discharged with water via a discharging pipe 7 followed by changing to the usual washing by passing raw water. The raw water is fed to the filter via the inlet pipe 13 to wash the filter member 2, and the waste water is stored in the tank 3' via the outlet pipe 10. After the filter member is stabilized or conditioned, a fluid flow is changed to the outlet pipe 11 followed by returning to the usual washing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an economical method for cleaning filters used in pretreatment of reverse osmosis devices and other general water treatments.

(Conventional technology) Reverse osmosis devices consume less energy and are easy to handle.
For these reasons, reverse osmosis membranes have recently been widely used in both large-scale and small-capacity devices for desalination of seawater and groundwater, reclamation of industrial water, concentration of juice, etc. Separation performance deteriorates due to various types of contamination such as suspended solids, colloids, other organic organisms, and slime that are present in the raw water. Especially among suspended solids, 0.3 to 5 μm
It is said that small suspended particles and colloids are the most likely to cause trouble, so after adding a coagulant to make them larger particles and making them easier to capture, filter them using a filter such as sand filtration, diatomaceous earth filtration, or precision filter. , feeding the reverse osmosis device. Such processing is also used in general filtration.

The filter gradually accumulates contaminant particles as it is operated, resulting in a large pressure loss, so it is washed as appropriate to restore separation performance.

As a prior art method for cleaning a filter, there is a method described in Japanese Patent Application Laid-open No. 59-42011, as shown in Figures 2 and 3. In Fig. 2, air is sent into the filter 1 from the lower end side of the filter 1 by a backwash blower B, the furnace material 2 and the water inside are stirred and mixed, and the pollutant particles are separated from the furnace material 2. In FIG. 3, the filtered water stored in the intermediate tank 3 provided on the inlet side of the high-pressure pump P2 is combined with the concentrated water in the pipe 4 from the reverse osmosis membrane module R and the pipe 5 from the intermediate tank 3.
The water mixed with the filtered water introduced through the filter is sent to the filter 1 as cleaning water through a pipe 6 by a bone pump or an ejector, and the pollutant particles and the injected fluid are discharged from a discharge pipe 7 at the top of the filter. When using filtered water for backwashing in this way, it is necessary to increase the amount of raw water supplied to the reverse osmosis device by 2 to 3%, and the capacity of the filter must be increased by that amount. However, there is a drawback that the power cost for water supply increases, resulting in high costs.

In another prior art shown in FIG. 4, an intermediate tank is not provided in the filtered water line, and an inlet pipe 8 for backwashing at the bottom of the filter l and a water passage washing pipe 9 at the top are provided for backwashing. This is done once a day for about 10 minutes using raw water from the lower backwashing inlet pipe 8.
Drainage water is discharged from the upper drain pipe 7, then raw water is supplied from the upper water washing pipe 9 and discharged to the outside from the lower discharge pipe 10.1 This water washing was carried out for about 1 to 2 hours. Afterwards, the filter is switched over and taken out from the filtered water take-out pipe 11, and normal operation begins. This cleaning method has the advantage of requiring only the piping to be installed, making the device simple, but has the disadvantage that the strainer 12 at the bottom of the filter can become clogged if the raw water is extremely contaminated.

Furthermore, discharging the flushing water as mentioned above is especially important in inland areas where well water is used as raw water, such as in Africa and the Middle East, because the raw water itself is stationary, so even though the water is used for cleaning, it cannot be wasted. The drawback is that it is not a more economical cleaning method.

(Problems to be Solved by the Invention) Therefore, in the conventional filter cleaning method, the water-washing wastewater that was discarded outside the system passes through the furnace material of the filter, making it relatively clean. Focusing on a certain point, the present invention aims to solve the various drawbacks of the prior art by reusing this water washing wastewater as water for backwashing.

(Means for Solving the Problem) The present invention is a filtration system characterized by storing wastewater generated during water washing performed after backwashing of a filter in a tank and reusing it as water for next backwashing. The present invention provides a method for cleaning equipment.

(Function) As mentioned above, the amount of raw water can be increased by temporarily storing the wastewater from water washing that is carried out following backwashing work in tanks, and using this water washing wastewater for the next backwashing. There is no need to take this into account, and it has the effect of reducing power costs.Moreover, the water used for backwashing is water that has passed through the furnace material of the filter, so it can be used for backwashing clogged filters. There is no problem in doing so.

(Example) An embodiment of the present invention will be described with reference to FIG.

A filter 1, which is filled with a furnace material 2 such as a sand layer, diatomaceous earth, or a cartridge, is connected to a raw water supply pipe 13, and has a filtered water outlet pipe 11 at the bottom, and a branched discharge pipe 10.
A tank 3' is connected to the filter 1, and the tank 3' is connected to the filter 1 via a pump 14 and a backwash water inlet pipe 15, and a backwash water discharge pipe 7 is provided at the upper part.

In the filter cleaning device configured as described above, during normal operation, raw water introduced from the raw water supply pipe 13 flows through the filter l.
The solid matter is removed by passing through the furnace material 2, and the filtered water is taken out from the take-out pipe 11 and sent to the next process, but the filter 1 becomes clogged due to long-term operation and the passage resistance becomes large. If so, start cleaning. That is, first, the operation is stopped, and the water flowing cleaning wastewater stored in the tank 3' from the previous cleaning process is transferred to the pump 1.
4. Backwash water is introduced into the filter l through the inlet pipe 15, backwashes the furnace material 2, and discharges the solid matter deposited in the gaps of the furnace material 2 from the discharge pipe 7 together with water. This backwash cleaning is done once a day.
The process is repeated once or twice for about 10 minutes, then switched, raw water is supplied from the raw water supply pipe 13, the furnace material 2 is flushed, and the waste water is stored in the tank 3' via the discharge pipe 1o. This water flushing is carried out for about 1 to 2 hours, and as the furnace material 2 becomes stable, the cleaning is completed, the pipe is switched to the outlet pipe 11, and normal operation is resumed. In this way, the tank 3' stores the flow-through cleaning wastewater each time and uses it as backwashing water for the next time.

(Effects) The present invention is a filter cleaning method in which the wastewater generated during water washing performed after backwashing the filter is stored in a tank and used as water for the next backwashing, so conventional methods are useless. Wastewater from flush washing that had been discarded is used for backwashing, and since this backwashing water is wastewater from flushing that was carried out after the previous backwashing process, solids are not filtered out. It is relatively clean and there is no problem even if it is used again for backwashing.Furthermore, there is no trouble caused by clogging of the strainer in the filter when the raw water is heavily contaminated as seen in the prior art. Since there is no disadvantage of increasing the amount of raw water and increasing the size of the filter body as explained in Fig. 2 and Fig. 3, a very economical cleaning method is possible, and this method is Reverse/:j:'M It can be widely used not only for pretreatment of the pressure method, but also for cleaning general filters.
This is particularly effective when using well water, which is in short supply in inland areas, as raw water, as it eliminates the waste of valuable water resources.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing one embodiment of the present invention,
FIG. 2, FIG. 3, and FIG. 4 are flow sheets in the conventional example. ■...Filter, 2...F material, 3...Intermediate tank, 3'...Tank, 7...Drain pipe,
8... Backwash cleaning water inlet pipe, 9... Water flow cleaning pipe, 10... Drain pipe, 11... Filtered ice removal pipe,
12...Lower strainer-113...Raw water supply pipe,
14... Pump, 15... Backwash cleaning water inlet pipe, B... Backwash proa, R... Reverse osmosis membrane module. Patent applicant Sasakura Machinery Co., Ltd. No. 1 -: -tar-

Claims (1)

[Claims] A filter cleaning method characterized by storing wastewater generated during water flow cleaning performed after backwashing the filter in a tank or the like and reusing it as water for the next backwash.