JP2001025616A - Spring filter apparatus and filtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively perform the back washing of a spring filter in a spring filter apparatus for precoating the spring filter with a filtering aid material and to reduce the use of cleaned water accompanied by back washing to the utmost. SOLUTION: A gas back washing means guiding compressed gas to the inner surface of a spring filter at a time of back washing and allowing compressed air to flow out of the gap provided to the peripheral surface of the spring filter while accelerating the same to separate and remove the solid in raw water adhering to the outer surface of the spring filter is provided and the removed solid is stored in a back washing water tank 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring filter device and a filtration method capable of filtering raw water having a solid content such as muddy water, backwashing the water efficiently and appropriately recovering its filtering ability quickly.

[0002]

2. Description of the Related Art As an apparatus for filtering a liquid containing a solid content, for example, there is an invention described in Japanese Patent Application Laid-Open No. Hei 8-196821. This uses a filter element in which a metal wire is spirally wound to form a coil spring, and a clearance for fluid flow is formed between adjacent wheels. A spring filter filtration device using this filtration element closes one end of a coil spring and opens the other end in a liquid-tight manner to a through hole of a tube sheet, and guides raw water to the outer peripheral side of the spring filter. By passing raw water from the outer surface side to the inner surface side of the spring filter, the solid content is filtered in the gap between the wheels. It is to be noted that a device for adhering a precoat agent to the outer periphery of a spring filter and filtering finer solids has also been proposed. Further, at the time of backwashing, it is configured such that purified water such as tap water is circulated from the inner surface side to the outer surface side of the spring filter to remove solids attached to the outer periphery of the filter. Further, there have been many ideas that the spring is extended by the cylinder at the time of the backwash, and the backwash is performed while increasing the gap.

[0003]

The conventional spring filter filtration device requires a relatively large amount of purified water such as tap water in order to backwash solids adhered to the outer periphery of the spring filter after being used for a certain period of time. And Therefore, it cannot be installed in places where purified water cannot be used, and there are restrictions on the installation locations. At the same time, the backwash water moves to the raw water side,
There is a disadvantage that the amount of raw water to be treated is increased. Further, according to the experiment, the effect of backwashing with purified water was relatively poor. Furthermore, a spring filter using a precoat agent requires a new precoat agent after backwashing,
There was a disadvantage that the running cost became high as a whole. Therefore, an object of the present invention is to solve these problems.

[0004]

According to a first aspect of the present invention, there is provided a spring filter wound in a coil shape, and a plurality of open ends of the spring filters communicate with respective filtered water flow holes. Tube plate 2, a can body 5 whose spring filter 1 is located on the raw water chamber side, and whose interior is partitioned into a raw water chamber 3 and a filtered water chamber 4 by the tube sheet 2, and an outer surface of the spring filter 1 A pre-coating means for pre-coating the filter aid 6 on the inner surface of the spring filter 1 and a pressurized gas introduced into the inner surface of the spring filter 1, and the pressurized gas is accelerated and discharged from a gap formed on the peripheral surface of the spring filter 1 so as to flow out. 1. A spring filter comprising gas backwashing means for separating and removing solids in raw water adhered to the outer surface of the raw water and backwashing water tank 7 for storing the removed solids. It is another filtration device.

According to a second aspect of the present invention, the spring filter 1 is made of a metal wire having a circular or substantially circular cross section, and the pressurized gas is pressurized air. 2. The spring filter filtration device according to claim 1, wherein the backwash is performed in a state where substantially no raw water exists on the outer periphery of the spring filter. According to the third aspect of the present invention, the pressure on the outer surface of the spring filter 1 is sufficiently higher than that on the inner surface, and the raw water is filtered by the spring filter 1. A solid-part consolidation filtration means for pressing and contacting with the filter aid 6 to consolidate the solid-state, and a solidified integrated material 8 of the solid content in raw water and the filter aid attached to the outer surface of the spring filter 1, A storage means for finely separating, removing and backwashing the united state by the pressurized gas and storing the consolidated united product 8 in the backwash water tank 7; The filter device according to claim 1 or 2, further comprising a filter aid recovering means for returning the integrated material (8) to the can body (5) and reusing it as a new filter aid.

According to the present invention, the raw water chamber 3 is provided.
Rectifying means 9 for rectifying the raw water supplied to the raw water chamber 3 is provided, and an inlet pipe 20 is led into the raw water chamber on the upstream side of the rectifying means 9, and the opening 20 a thereof is connected to the can body 5.
The spring filter filtration device according to any one of claims 1 to 3, which is disposed so as to face a bottom surface of the spring filter. The present invention according to claim 5, wherein the filter aid 6 for precoating the outer surface of the spring filter 1 by the precoating means is diatomaceous earth, wherein the filter aid 6 is diatomaceous earth. It is a spring filter filtration device.

According to a sixth aspect of the present invention, each open end of the plurality of spring filters 1 wound in a coil shape with one end closed is communicated with each filtered water flow hole of the tube sheet 2. Positioning the spring filter 1 on the raw water chamber 3 side, and partitioning the interior of the can body 5 into the raw water chamber 3 and the filtered water chamber 4 by the tube sheet 2;
A pre-coating step of pre-coating a filter aid 6 on the outer surface of the filter, a filtration step of increasing the pressure on the outer side of the spring filter 1 sufficiently from that on the inner side, and filtering the raw water through the spring filter 1; A gas backwashing process in which pressurized gas is guided to the inner surface of the spring filter, and the pressurized gas is accelerated to flow out of a gap around the outer periphery of the spring filter to separate and remove solids in raw water adhering to the outer surface of the spring filter. And a storing step of storing the obtained solid content in the backwash water tank 7.

According to a seventh aspect of the present invention, the spring filter 1 is made of a metal wire having a circular or substantially circular cross section, and the pressurized gas is used as pressurized air. 7. The method according to claim 6, wherein the backwash is performed in a state where the raw water does not substantially exist in the outer periphery of the spring filter. According to the present invention, the pressure on the outer surface side of the spring filter 1 is sufficiently higher than that on the inner surface side, and raw water is filtered by the spring filter 1. And the solidification in the raw water adhering tightly to the outer surface of the spring filter and the solidified integrated product 8 of the filtration aid and the solid content. A gas backwashing step of separating and removing finely in the integrated state; and a consolidation integrated body 8 removed in the gas backwashing step and stored in the backwash water tank 7 in the can body 5.
And a filter aid recovering step of reusing the filter aid as a new filter aid.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a spring filter filtration device of the present invention, and FIG. 2 is a partially broken elevation view of a can body 5 having the spring filter. 3 is an enlarged explanatory view in which a filter aid 6 is arranged on the outer periphery of the spring filter 1, FIG. 4 shows a filtering state of the spring filter 1, and FIG. 5 is an enlarged view showing the backwashing state, respectively. It is. FIG. 6 is an explanatory perspective view of the backwashing state. The apparatus includes a can body 5 containing a large number of spring filters 1, a precoat tank 18 for precoating the outer periphery of the spring filter 1, a compressor 13 for backwashing, and a backwash containing solids separated during backwashing. And a water tank 7. As shown in FIG. 2, the can body 5 has a tube sheet 2 disposed at an upper portion inside thereof, and a filtered water chamber 4 is provided above the tube sheet 2, and a raw water chamber 3 is provided below the tube sheet 2. The tube sheet 2 has a large number of filtered water flow holes, and the open end of the spring filter 1 is connected to each of the flow holes, and the connection is maintained in a liquid-tight manner.

Each spring filter 1 is open at the upper end and closed at the lower end. As shown in FIGS. 3 and 4, the spring filter 1 is formed by winding a wire having a substantially circular cross section in a coil shape. And 95μ between each wheel
Very small projections are formed at regular intervals so that a gap of about m is formed, or the top is cut very slightly, leaving a part of the wire. And they are formed tightly, and a slight gap is formed between each wheel. The lower end of the coil is closed, and an annular part 1a is provided at the upper end. The upper end of the annular part 1a is connected to the communication hole of the tube sheet 2. In addition, a fastening bolt 1b for setting the gap between the wheels constant is inserted through the center of the spring filter 1.

Next, an inlet pipe 20 is communicated with the lower end of the can 5, and an opening 20 a provided at the end thereof opens downward on the axis of the can 5. A raw water tank 14 is connected to the inlet pipe 20 via a valve 17b, a raw water pump 15, and a valve 17c. At the same time, the precoat tank 18
a, connected via a precoat pump 16; The lower end of the can 5 is connected to the backwash water tank 7 via a valve 17e, and the backwash water tank 7 and the inlet pipe 20 are connected to the valve 17e.
b, connected via a precoat pump 16; A drainage tank 19 is connected to the upper end of the can body 5 via a valve 17j and a valve 17g. Furthermore, the compressor 13 is a valve 17
i, connected via valve 17h. The valve 17j is a three-way valve, and one pipe connected to the valve 17j communicates with the precoat tank 18. The raw water chamber 3 of this can 5 is shown in FIG.
As shown in FIG. 1, a lattice-shaped rectifying means 9 is provided at a lower portion between the inlet pipe 20 and the lower end of the spring filter 1. The tip of the inlet pipe 20 is a can 5
May be opened in the can wall without projecting into the inside of the can. Also,
The grid-shaped rectifying means 9 may be omitted.

[0012]

[Usage method] [Precoating step] First, it is necessary to precoat the outer periphery of the spring filter 1 before performing the filtering operation. The precoat opens the valves 17a and 17g, connects the valve 17j to the precoat tank 18 side, and closes the other valves. Then, the precoat pump 16 is driven to supply the powdered diatomaceous earth stored in the precoat tank 18 together with the fresh water into the raw water chamber 3 of the can 5. Then, fresh water is circulated, and a filter aid 6 made of diatomaceous earth powder is attached to the outer periphery of each spring filter 1 to a uniform thickness as shown in FIG.

[Filtration Step] Next, the valve 17a is closed, and the valve 17j is connected to the communication side between the can body 5 and the drainage tank 19. Then, the valves 17c and 17d are opened so that the raw water tank 14 and the inlet pipe 20 can communicate with each other. Next, the raw water pump 15 is driven to supply the raw water in the raw water tank 14 from the opening 20a into the raw water chamber 3 as shown in FIG. The opening 20a of the inlet pipe 20 opens downward on the axis of the can body 5, from which raw water 12 passes through the rectifying means 9 and is guided from the outer periphery of the multiple spring filters 1 into the inside. At this time, a layer of the filter aid 6 is present on the outer periphery of the spring filter 1, and when passing through the gap between the filter aids 6, the solid content of the raw water is removed.
From the filtered water chamber 4 to the filtered water tank 19. In addition,
During the operation of the precoat pump 16, the outer peripheral side of the spring filter 1 becomes higher in pressure than the inner peripheral side thereof due to the pressurizing force, and the solid content in the raw water is captured by the filter aid 6 and the precoat pump 16 is pressurized. It becomes compacted by pressure and becomes integral with the filter aid 6. That is, the spring filter 1
Is formed on the outer periphery of the solidified body 8 in which the filter aid 6 and the solid content of the raw water 12 are in close contact.

[Gas Backwashing Step] Next, solids in the raw water 12 adhere to the outer periphery of the spring filter 1 and the filter aid 6 and the consolidated compact 8 composed of the filter aid 6 are removed.
When it grows significantly on the outer periphery of the surface, back washing is performed next. At this time, the raw water 12 in the raw water chamber 3 of the can 5 is removed. Then, the valves 17i, 17h and 17e are opened and the others are closed.
Next, the compressor 13 is driven and the compressed air is supplied to the filtration water chamber 4.
Supply within. Then, the filtered water remaining in the filtered water chamber 4 is pushed out from the inner surface side of the spring filter 1 to the outer surface side. Next, the compressed air flows out of the gap of the spring filter 1 into the raw water chamber 3. Then, as shown in FIG. 5, the backwash gas 11 flows out of the gap between the wheels of the spring filter 1. At that time, when the air passes through the gap, it is accelerated at high speed and reaches subsonic speed. Thereby, the consolidated consolidation material 8 is subdivided and reliably removed from the outer periphery of the spring filter 1. Then, it is captured in the backwash water tank 7.

[Re-pre-coating step] The consolidation-integrated material 8 thus captured becomes fine particles, which can be used as the filter aid 6 at the time of re-pre-coating. That is, the filter aid 6 from the precoat tank 18 is supplied without supply or slightly, and the compacted integrated product 8 in the backwash water tank 7 is passed through the valve 17b and the precoat pump 16 through the inlet pipe.
An appropriate amount is flowed into the raw water chamber 3 through the opening 20a of 20 and is attached to the outer periphery of the spring filter 1 to an appropriate thickness. Then, a layer of a filter aid is formed by the compacted integrated product 8 itself. Next, the filtration step may be repeated. The backwash water tank 7 and the raw water tank 14 can be connected by a pipe (not shown). Further, a container for capturing the consolidated consolidation material 8 can be separately stored in the backwash water tank 7. Further, in the above, the compressor 13 constitutes the gas backwash means in the present invention.

[0016]

EXAMPLE The muddy water produced by the excavation of the ground was used as raw water and filtered by the present filtration apparatus shown in FIGS. As a filter aid, a powdery and sintered body of diatomaceous earth having an average particle size of about 20 μm is used. Coil diameter 15 as spring filter
300 mm, length 300 mm, mesh 95 μm
Use ~ thousands. And 10 filter aids per filter
g Completely precoat the outer periphery of each spring filter. The internal pressure of the raw water chamber is increased to 6 kg / c by a pressure pump
m ² and the mud was filtered. The mud was completely filtered and turned into fresh water. A large amount of mud was firmly attached to the outer periphery of the spring filter. Then, remove the muddy water in the raw water chamber,
Compressed air from compressor (pressure 3kgf / c
m ² ) was supplied to the filtered water chamber. Thereby, the attached mud was completely removed from the outer surface of the spring filter. Observation of the mud revealed that, in particular, what had adhered to the surface of the spring filter was formed into a granular form in a state of being consolidated and compacted with the diatomaceous earth. Attempts have been made to attach a suitable amount of them to the outer periphery of the spring filter, which has been found to have a filtering effect itself.

[0017]

Comparative Experimental Example Next, a comparative experiment between the backwashing by the gas backwashing means of the present invention and the backwashing by the conventional liquid backwashing means will be described. Table 1 shows this and is performed under the following experimental conditions. First, polluted water is used as target raw water. In addition, the coil diameter is 15 mm and the length is 30 as a spring filter.
Three of 0 mm and a mesh of 95 μm are used. Then, the outer periphery of each spring filter is completely pre-coated with 30 g (10 g / piece) of the filter aid. A compressor with a pressure of 3 kgf / cm ² is used.

First, the polluted water is filtered under such conditions. After sufficiently filtering the contaminated water, the compressor blows 3 kgf / cm ^{2 of} compressed air from the upper part of the casing of the spring filter for 5 seconds, and then provides a stop time of about 5 seconds, and repeats this cycle 5 times. At this time, backwashing is performed in a state where raw water does not exist on the outer peripheral side of the spring filter. Then, after filtering the raw water, the inlet pressure at the initial stage of filtration and the flow rate after air backwashing are measured. As a comparative example, a conventional water backwash is performed after filtering the contaminated water in the same manner. That is, the pressure is 3 kgf / cm
Apply purified water to the inside of the spring filter by applying the internal pressure of ² , and pressurize for 5 seconds. Next, a stop time of about 5 seconds is provided, and pressure is applied again. This cycle is repeated five times.
Thereafter, the raw water is filtered, and at that time, the inlet pressure at the initial stage of the filtration and the flow rate after the water backwash at that time are measured.

The air backwashing experiment and the water backwashing experiment were performed three times, and the results shown in Table 1 were obtained for each.
For example, in the first test, the flow rate after air backwash was 1 ml
/ Sec, and the flow rate after water backwashing is 0.65 ml / sec.
c. The inlet pressure after air backwashing is 1 kgf /
cm ² and the inlet pressure after water backwashing is 1.1 kgf / c
m ² . As a result, the flow rate after the air backwash is 1.5 times the flow rate after the water backwash, and it can be seen that the backwash effect of the air backwash is better than that of the water backwash. The flow ratio between the two was 1.8 times in the second case, and 1.9 times in the third case. And the average thereof was about 1.7 times, and it was proved that the backwashing effect by air backwashing was significantly higher. Further, it can be seen that the inlet pressure after the air backwash is lower than the inlet pressure after the water backwash, and the solid content on the outer surface of the spring filter is sufficiently removed. In the above test, when pressurized with compressed air in the air backwash, since a certain amount of water exists in the spring filter and the casing, water is initially blown out from the outer periphery of the spring filter for about 2 seconds. Then, a mixture of water and air was blown out, and then only air was blown out. In the water backwashing, tap water was stored in a tank, pressurized, and supplied to the inner surface side of the spring filter.

[0020]

[Table 1]

[0021]

According to the first aspect of the present invention, a spring filter is provided after raw water is filtered by the present filtering apparatus.
Pressurized gas is introduced to the inner surface of the
A gas backwashing means is provided for acceleratingly flowing out pressurized gas from a gap in the peripheral surface of the spring filter 1 to separate and remove solids in raw water adhering to the outer surface of the spring filter 1. By this gas backwashing means, it is possible to provide a filtering device having a remarkably large backwashing effect as compared with ordinary liquid backwashing means. This is because when the pressurized gas flows out of a slight gap in the peripheral surface of the spring filter 1, the gas has a significantly smaller fluid resistance in the gap than the liquid, and the flow velocity can be increased. Further, since the present invention uses gas for backwashing, it does not require purified water such as tap water at the time of backwashing, and can be a filtering device that can be installed anywhere, selecting a place. Further, the solid content compacted on the outer periphery of the spring filter by the pressurized gas can be easily separated as a small lump, and can be separated as fine solid content. Therefore, it can be reused as a filter aid. Further, the backwashing by the gas backwashing means does not cause a problem of an increase in raw water due to the backwashing unlike the conventional liquid backwashing. That is, in the case of the conventional water backwash, there was a problem that the backwash water returned to the raw water and the raw water that had to be treated increased, but in the case of the gas backwash, the raw water increased. Does not occur.

According to a second aspect of the present invention, the spring filter 1 is made of a metal wire having a circular or substantially circular cross section, and pressurized air is used as a pressurized gas. The backwashing is performed in a state where substantially no raw water exists. for that reason,
Backwashing can be easily performed using a normal compressor or the like. Further, by using a metal wire having a circular or substantially circular cross section, solids in raw water clogged in gaps can be more easily separated and removed from the inner surface side. Furthermore, at the time of backwashing, backwashing is performed in a state where substantially no raw water is present on the outer periphery of the spring filter 1, so that the air flow of the pressurized gas flowing through the gap of the spring filter 1 becomes faster and the backwashing is effected. Can be done Furthermore, when a circular wire is wound into a coil shape and pressurized gas flows out from the inner surface side to the outer surface side, the cross-section between the rings is formed in a tapered nozzle shape on the inner surface side between the rings, and the outer surface side is formed. Then, it is opened like a divergent nozzle. Therefore, at the time of backwashing the pressurized gas, the air flows at a high sound velocity through the minimum gap, and in particular, the clogged portion in the gap can be completely removed. And since it is formed in the shape of a divergent nozzle on the outer surface side, air flows smoothly along the outer surface and the outer surface of the wire can be thoroughly air-cleaned.

According to the third aspect of the present invention, when the raw water is filtered by the spring filter 1, the solid content in the raw water is brought into pressure contact with the filter aid 6 with the filtration to integrally consolidate the raw water. A solid consolidation filtration means is provided, and at the time of back washing, the consolidation integrated material 8 composed of the solid content and a filter aid is finely separated and removed by pressurized gas for back washing, and is stored in the back washing water tank 7. . Since there is a filter aid recovering means for returning the consolidated consolidation material 8 stored in the backwash water tank 7 to the can body 5 and reusing it as a new filter aid, the necessary amount of the new filter aid 6 is minimized. It is possible to provide a filtration device with low running cost. According to the present invention, the straightening means 9 is provided in the raw water chamber 3, the inlet pipe 20 is led to the upstream side thereof, and the opening 20 a is arranged to face the bottom surface of the can 5. Therefore, the filtered water flows evenly through the plurality of spring filters 1, and an efficient filtration device can be provided. According to the fifth aspect of the present invention, since the filter aid 6 to be precoated is diatomaceous earth, the filtration effect is high and the running cost can be relatively low.

According to the sixth aspect of the present invention, since a gas backwashing step using a pressurized gas is used, a high backwashing effect and efficient filtration can be performed. At the same time, the use of tap water or the like at the time of backwashing becomes unnecessary, and an easy-to-handle filtration method that selects an installation location is provided. According to a seventh aspect of the present invention, a metal wire having a circular or substantially circular cross section is used for the spring filter 1 and pressurized air is used as the pressurized gas. Since the backwash is performed in a state where no raw water exists, efficient filtration can be performed. The present invention according to claim 8 has a filtration aid recovery step of returning the consolidated consolidation material 8 removed in the gas backwashing step to the can body 5 and reusing it as a new filtration aid. And a filtration method with a low running cost can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a spring filter filtration device of the present invention.

FIG. 2 is a partially broken elevation view of a can body 5 having a spring filter of the filtration device.

FIG. 3 is an enlarged explanatory view in which a filter aid 6 is arranged on the outer periphery of a spring filter 1 of the filtration device.

FIG. 4 is an enlarged explanatory view showing a filtration state of a spring filter 1 of the filtration device.

FIG. 5 is an enlarged explanatory view showing a backwashing state of a spring filter 1 of the filtration device.

FIG. 6 is an explanatory perspective view of a backwash state of the spring filter 1 of the filtration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spring filter 1a Ring part 1b Bolt 2 Tube plate 3 Raw water chamber 4 Filtration water chamber 5 Can body 6 Filtration aid 7 Backwash water tank 8 Consolidation integrated material 9 Straightening means 10 Filtration water 11 Backwash gas 12 Raw water 13 Compressor 14 Raw water Tank 15 Raw water pump 16 Precoat pump 17a-17j Valve 18 Precoat tank 19 Filtration tank 20 Inlet pipe 20a Opening

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masao Sugawara 5-37-1, Kamata, Ota-ku, Tokyo Toshiba Plant Construction Corporation F-term (reference) 4D066 BA01 BB06 BB08 CA02 DA01 FA03

Claims (8)

[Claims] 1. A spring filter 1 wound in a coil shape, a tube sheet 2 having a plurality of open ends of the respective spring filters 1 communicating with filtered water flow holes, respectively; A can body 5 whose interior is partitioned by a tube sheet 2 into a raw water chamber 3 and a filtered water chamber 4, a precoat means for precoating an outer surface of the spring filter 1 with a filter aid 6; Guide the pressurized gas to the inner surface of the filter 1,
Gas backwashing means for acceleratingly flowing out the pressurized gas from a gap in the peripheral surface of the spring filter 1 to separate and remove solids in raw water adhering to the outer surface of the spring filter 1; And a backwash water tank 7 for storing water. 2. The spring filter 1 is made of a metal wire having a circular or substantially circular cross section in outer circumference, and the pressurized gas is pressurized air. 2. The spring filter filtration device according to claim 1, wherein the backwash is performed in a state where the spring filter does not exist. 3. The pressure on the outer surface of the spring filter 1 is made sufficiently higher than that on the inner surface thereof to filter raw water by the spring filter 1 and, along with the filtration, solid matter in the raw water to a filter aid 6. A solid content consolidating filtration means for pressurizing and adhering to the surface of the spring filter 1 and a solid consolidation material 8 of raw water adhering to the outer surface of the spring filter 1 and a consolidation filter aid 8 by the pressurized gas. Storage means for separating and removing finely in the integrated state and backwashing, and for storing the consolidation integrated material in the backwash water tank 7; and the consolidation integrated material 8 stored in the backwash water tank 7 for the can. 3. The filter device according to claim 1, further comprising a filter aid recovering means for returning the filter to the body 5 and reusing the filter aid as a new filter aid. 4. A rectifying means 9 for rectifying the raw water supplied to the raw water chamber 3 is provided in the raw water chamber 3, and an inlet pipe 20 is led into the raw water chamber on the upstream side of the rectifying means 9. The spring filter filtration device according to any one of claims 1 to 3, wherein the opening (20a) is arranged to face the bottom surface of the can body (5). 5. The spring filter filtration device according to claim 1, wherein the filter aid 6 for precoating the outer surface of the spring filter 1 by the precoating means is diatomaceous earth. 6. An open end of each of a plurality of spring filters 1 wound in a coil shape with one end closed is communicated with a respective filtered water flow hole of a tube sheet 2, and the spring filter 1 is connected to raw water. A step of partitioning the interior of the can body 5 into a raw water chamber 3 and a filtered water chamber 4 by means of the tube sheet 2 and a precoating step of precoating the outer surface of the spring filter 1 with a filter aid 6; A filtration step of increasing the pressure on the outer surface side of the spring filter 1 sufficiently from that on the inner surface side and filtering raw water through the spring filter 1; and introducing a pressurized gas to the inner surface side of the spring filter to form a gap around the outer periphery of the spring filter. Gas backwashing process to separate and remove solids in raw water adhering to the outer surface of the spring filter by accelerating outflow of the pressurized gas from the filter, and backwashing the removed solids Spring filter filtration method characterized by having a storing step of storing the link 7. 7. The spring filter 1 is made of a metal wire having a circular or substantially circular cross-sectional outer periphery, and the pressurized gas is used as pressurized air. 7. The method for filtering a spring filter according to claim 6, wherein the back washing is performed in a state where the back filter does not exist. 8. The pressure on the outer surface of the spring filter 1 is sufficiently higher than that on the inner surface thereof to filter raw water by the spring filter 1 and, along with the filtration, solid matter in the raw water to a filter aid 6. A solid content consolidation filtration step of pressurizing and adhering to the surface of the spring filter, and a consolidation integrated material 8 of the solid content in raw water and a filter aid adhered to the outer surface of the spring filter in a pressurized air. A gas backwashing step of finely separating and removing in the integrated state; and a consolidation integrated body 8 removed in the gas backwashing step and stored in the backwash water tank 7 and returned to the can body 5 for new filtration. The method for filtering a spring filter according to claim 6 or 7, further comprising a filtration aid recovery step of reusing the auxiliary material.