JPH0255082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting and stopping a backwash siphon tube of a gravity filtration device.

Conventionally, when starting each siphon in a gravity-type filtration device, a vacuum pump or ejector was connected to the top of the siphon tube, and the vacuum pump or ejector reduced the air pressure in the siphon tube to start the siphon. A drawback is that an expensive vacuum pump or pressure water pump for the ejector must be provided as a power source.

The present invention compensates for these drawbacks of the conventional method and provides a method for reliably starting and stopping a backwash siphon pipe without requiring a special power source, at low production cost, and with simple operation. This is the purpose.

In other words, the present invention provides a filter basin 3 which is partitioned by a partition wall 14 into a floor 6 and a backwash wastewater inflow chamber 13, which is adjacent to and separated from the backwash wastewater inflow chamber 13, and which is separated from and adjacent to the backwash wastewater inflow chamber 13. a backwash drainage retention culvert 16 that maintains the water level below the water level at which the backwash water overflows; and an overwater culvert that communicates with the bottom of the floor 6 and maintains the water level above the water level at which the backwash water of the floor 6 overflows. 9, the backwash wastewater inflow chamber 13 and the backwash wastewater retention conduit 16,
The backwashing siphon pipe 5 is composed of a backwashing siphon pipe 5, which is an inverted U-shaped pipe having a bent part above the water level and communicating with the water, and both ends of which are sealed with water. In a gravity-type filtration device in which water is discharged through a backwashing siphon pipe 5 and the excess water is caused to flow back to the floor 6 by the water head held by the overwater conduit 9, the backwashing siphon pipe 5 is activated and When stopping the backwashing siphon pipe 5, the distance H ₁ between the water surface of the backwashing wastewater inflow chamber 13 and the upper part of the backwashing siphon pipe 5 when the backwashing siphon pipe 5 is to be started, and the low level water level in the water tank 19. The water tank 1 is sealed so that the distance H ₂ from the water seal water level in the backwash drainage retention conduit 16 of the drain pipe 23 attached to the water tank 19 (described later) is in the relationship H ₁ <H ₂ .
9, one end of the communication pipe 20 is connected to the water tank 19, and the other end of the communication pipe 20 is connected to the upper part of the backwashing siphon pipe ₅ via the automatic valve V1. A siphon stop automatic release valve V ₃ is provided on the communication pipe 20 between the siphon pipe ₁ and the backwash siphon pipe 5 or on the upper part of the backwash siphon pipe 5, and the high level water level in the water tank 19 is detected in the water tank 19. Supply pipe 21 provided with a water surface detector 25 and having an automatic valve V ₄ linked to the water surface detector 25
is connected to the water tank 19, and a drain pipe 23 is provided in the water tank 19, the lower end of which is sealed with the water surface of the backwash drainage retention conduit 16, and the upper end of which penetrates the water tank 19 and opens within the water tank 19. An outer cylindrical pipe 29 which has an inner diameter larger than 23 and has a water flow opening 30 below the opening of the drain pipe 23 in the water tank 19 and whose upper part is sealed is inserted into the water tank 19 so as to cover the drain pipe 23 in the water tank 19. An exhaust pipe 28 having an automatic valve V ₂ is connected to the upper part of the outer cylindrical pipe 29, and the capacity of the water tank 19 is changed from the high water level to the low level. When the water is discharged from the drain pipe 23 to the water level, the backwashing siphon pipe 5
By suctioning the air present inside the and communication pipe 20, the water in the backwash drainage inflow chamber 13 is sucked up to a capacity that drives the backwash siphon pipe 5, and the automatic valve _V1 and the siphon stop automatic release valve
Open V ₃ to release water tank 19 to the atmosphere, and open automatic valve V _4.
is opened and water is poured into the water tank 19, and when the water level reaches the above-mentioned high level, the automatic valve _V4 is closed and the siphon stop automatic release valve _{V3 is} closed. The backwashing siphon pipe ₅ is opened by opening the valve V 2 to discharge the water in the water tank 19 from the drain pipe 23 according to the water head difference, and then immediately closing the automatic valve V ₂ to start the backwashing siphon pipe 5. Gravity characterized by sequentially repeating the activation and the stop of the backwashing siphon pipe 5 which closes the automatic valve V ₁ and opens the siphon stop automatic release valve V ₃ to stop the activated backwashing siphon pipe 5. The present invention relates to a method for starting and stopping a siphon tube for backwashing in a filtration system.

The present invention will be explained in detail below with reference to the drawings.

Each of the drawings is a longitudinal cross-sectional view showing an example of an embodiment of a gravity-type filtration device using the method for starting and stopping a backwashing siphon pipe of the present invention, and as shown in FIG. A plurality of filter ponds 3 arranged in a line in the vertical direction are provided in the filter device 1, and a raw water inflow conduit 2 common to each filter pond 3 is provided above the filter ponds 3. In addition, a raw water distribution chamber 4 is provided on the side of the raw water inflow conduit 2 corresponding to each filter pond 3, and a water seal weir 2 is provided outside the raw water distribution chamber 4.
A raw water inflow chamber 15 is provided through a water inflow chamber 7 , and the raw water distribution chamber 4 and the raw water inflow conduit 2 are connected through a water passage siphon pipe 22 . Further, the filter basin 3 is partitioned into two chambers by a partition wall 14, one chamber is used as a backwash wastewater inflow chamber 13, and the chamber 13 and the raw water inflow chamber 15 are communicated through a raw water pipe 24. Further, a support bed 7 is provided below the other chamber of the over pond 3, a floor 6 is formed above the support bed 7, and above the floor 6,
and a backwash drainage gutter 1 at the height of the upper end of the partition wall 14.
A plurality of partition walls 14 of the backwash drainage gutter 12 are provided.
Open one end of the side. In addition, an overwater collection chamber 8 is provided below the support floor 7, and the chamber 8 is further connected to an overwater conduit 9.
The overflow water flowing out from each overwater basin 3 is made to flow through the overwater collection chamber 8 and into the overflow channel 9. Further, the overwater drain 9 is communicated with the overwater outflow drain 10 via an overflow weir 11, and the overflow weir 11 is provided so as to be higher than the upper end of the backwash drainage gutter 12, so that the water level of the overwater drain 9 is is maintained approximately constant at the height of the overflow weir 11. In addition, a backwash wastewater retention conduit 16 is arranged adjacent to and separated from the backwash wastewater inflow chamber 13, and the backwash wastewater retention conduit 16 and the backwash wastewater inflow chamber 13 of the over pond 3 are connected to the water level of the over pond 3. An inverted U with a bent part higher up and water-sealed at both ends.
It communicates with a backwashing siphon tube 5 consisting of a double-shaped tube.

Further, a backwash wastewater outflow culvert 18 is provided further outside the backwash wastewater retention culvert 16, and the backwash wastewater retention culvert 1
6 and the backwash wastewater outflow conduit 18 are communicated via a water seal weir 17 whose height is lower than the partition wall 14, and the water level of the backwash waste water retention conduit 16 is kept constant at the height of the water seal weir 17.

In addition, the sealed water tank 19 is located above the backwash wastewater retention conduit 16, and the water surface of the backwash wastewater inflow chamber 13 and the upper part of the backwash siphon pipe 5 when the backwash siphon pipe 5 is to be started. As will be described later, the distance H ₁ between the low level water level D in the water tank 19 and the water surface of the backwash drainage retention conduit 16 is H _{1 <}
Set up so that the relationship is H ₂ .

Note that the capacity of the water tank 19 will be described later.

Furthermore, in this embodiment, the upper end of the water tank 19 is provided at almost the same height as the water surface of the raw water inflow conduit 2, so that raw water can be poured into the water tank 19 using the water head of the raw water inflow conduit 2. However, the present invention is not limited to this, and as long as the relationship H ₁ <H ₂ is satisfied and other water is filled into the water tank 19, its vertical position may be any. In addition, the horizontal position of the water tank 19 is also changed to the backwash drainage retention conduit 16.
It is not limited to installing directly above the.

Further, a drain pipe 23 having a thickness that allows the water in the water tank 19 to be quickly drained is provided below the water tank 19, and the lower end of the drain pipe 23 is opened below the water surface of the backwash wastewater retention conduit 16. The water is sealed to prevent air from rising up the drain pipe 23 and flowing into the water tank 19.

Further, the upper end of the drain pipe 23 is passed through the water tank 19 and opened at the lower part of the water tank 19, and the drain pipe 23 inside the water tank 19 is opened at the lower part of the water tank 19 as shown in FIG.
An outer cylindrical pipe 29 with a sealed upper part and a water flow port 30 below the opening of 3 is fixed in the water tank 19 so as to cover the drain pipe 23 in the water tank 19, and further the upper part of the outer cylindrical pipe 29 is Connect the exhaust pipe 28 with automatic valve V ₂ to.

Further, one end of the communication pipe 20 is connected to the upper part of the water tank 19, and the other end is connected to the upper part of the backwashing siphon pipe 5 via an automatic valve _V1 and a siphon stop automatic release valve _V3 . Alternatively, the communication pipe 20 before the automatic valve V ₁ may be branched and connected to the upper part of the water flow siphon pipe 22 via the automatic valve V ₅ and the siphon stop automatic release valve V ₆ .

Note that the communication pipe 20 in front of the automatic valve V ₁ can be further branched to communicate with a backwash siphon pipe (not shown) and a water flow siphon pipe (not shown) of another filter basin.

Incidentally, the siphon stop automatic release valve V ₃ may be provided at the upper part of the siphon pipe 5 for backwashing.

In addition, the water tank 19 and the raw water inlet culvert 2 are communicated via the supply pipe 21 having an automatic valve _V4 . Needless to say, the other end of 21 is connected to its supply source.

In addition, a water surface detection meter 25 is provided in the water tank 19, and the water surface detection meter 25 is linked with the automatic valve _V4 , so that when the water surface of the water tank 19 reaches the high water level A, the water surface detection meter 2
Automatic valve V ₄ linked to V 5 closes and the supply of raw water is stopped.

Furthermore, the automatic valve V ₁ and the siphon stop automatic release valve V ₃ are opened to open the water tank 19 to the atmosphere, and the automatic valve V ₂ is closed to open the automatic valve V ₄ of the supply pipe 21.
When raw water is supplied to the water tank 19 by opening the tank, the water level in the water tank 19 rises as shown in FIG. The height of the drain pipe 23 in the water tank 19 is adjusted so that the water level in the water channel 31 reaches the upper end of the drain pipe 23 almost at the same time as the water surface in the water tank 19 reaches the high water level A.

Further, the low level water level D of the water tank 19 mentioned above is lower than the high level water level A, and the capacity of the water tank 19 from the water level A to D is the backwashing siphon pipe 5.
The water tank 1 shall have sufficient capacity to suck and depressurize the air contained inside the communication pipe 20 and the water tank 1.
When the water in 9 is discharged through the drain pipe 23 with a water head difference, the backwashing siphon pipe 5 is configured to start while the water level reaches from A to D.

When carrying out filtration in such a gravity-type filtration device 1, the water flow siphon pipe 22 is first activated, but as shown in FIG _. If the siphon stop automatic release valve V ₆ is attached to the communication pipe between the automatic valve V ₅ and the siphon pipe 22 for water passage, the present invention applies. By using the water tank 19 to be used, the water flow siphon pipe 22 can be activated. That is, the automatic valve V ₁ and the siphon stop automatic release valve V ₃ are opened to open the water tank 19 to the atmosphere, and the automatic valve V ₂ is closed and the automatic valve V ₄ of the supply pipe 21 is opened to drain raw water from the raw water inlet conduit 2. supply
Additionally automatic valve V ₁ and siphon stop automatic release valve
The water tank 19 may be opened to the atmosphere by opening the automatic valve _V5 and the siphon stop automatic release valve _V6 instead of _V3 .

When the water level of the water tank 19 rises to the high water level A, the automatic valve _V4 linked to the water surface detector 25 closes, and the supply of raw water is automatically stopped. Also, when the supply of raw water stops, close automatic valve _V1 .
Also, when water is supplied to the water tank 19 in this way, the water channel 3
As the water rises, the air in the water channel 31 is compressed, and the air in the upper part of the outer tube 29 and in the drain pipe 23 becomes pressurized.

Next, when the siphon stop automatic release valve V ₆ of the water flow siphon pipe 22 is closed, the automatic valve V ₅ is opened, and the automatic valve V ₂ is further opened, the pressurized air in the upper part of the outer cylinder pipe 29 flows through the air vent pipe 28. The air pressure at the upper part of the outer tube 29 decreases, and the water in the water tank 19 flows through the water flow port 30 of the outer tube 29 and the water channel 31.
After that, the water is rapidly discharged from the drain pipe 23, and the water level in the water tank 19 is lowered. As the water level decreases, air in the water passage siphon pipe 22 passes through the communication pipe 20 to the water tank 1.
The air pressure in the siphon tube 22, which is sucked into the siphon tube 9 and sealed by the raw water inflow conduit 2 and the water flow pipe 4, rapidly decreases, and the water level in the siphon tube 22 rises, causing the water flow through the siphon tube 22 to rise. starts.

When water starts to drain from the drain pipe 23, immediately close the automatic valve _V2 . If the automatic valve V ₂ is left open, it will not be possible to apply suction to the communication pipe 20, so it is important to close the automatic valve V ₂ as soon as water begins to drain from the drain pipe 23. A timer is normally used to determine the timing of this opening/closing, but in some cases, the water level detector 25 and automatic valve V ₂ may be communicated so that the water level detector 25 can detect when the water level in the tank 19 begins to drop. The automatic valve V ₂ may be closed based on the detection.

In this way, the raw water in the raw water inflow conduit 2 flows through the water flow siphon pipe 22 into the raw water distribution chamber 4, then into the raw water inflow chamber 15, and further through the raw water pipe 24 into the over pond 3.
The excess water flows into the backwash wastewater inlet chamber 13, passes over the partition wall 14 and passes through the floor 6 in a downward flow, and the excess water flows out through the excess water collection chamber 8, the excess water conduit 9 and the excess water outflow conduit 10.

As described above, the water flow siphon pipe 22 has a smaller air capacity in the siphon, for example, about 1/12, compared to the backwashing siphon pipe 5, and when trying to start the water flow siphon pipe 22, Distance between the water surface on the inflow side and the top of the water flow siphon pipe 22
H ₃ is much smaller than H ₁ in a normal gravity filtration device, and there is a relationship of H ₃ ≪ _{H 2.} Therefore, if the water tank 19 used in the method of the present invention is used, the amount of water in the water tank 19 can be increased by the operation described above. The water can be rapidly discharged and the water flow siphon pipe 22 can be easily activated.

When the water flow siphon pipe 22 starts, the water tank 1
The discharge of raw water from the discharge pipe 23 of 9 is stopped, and the water level in the water tank 19 becomes constant. Next, the automatic valve V ₅ is closed, the automatic valve V ₁ is opened, and the inside of the water tank 19 is opened to the atmosphere by the opened siphon stop automatic release valve V ₃ , and the water in the water tank 19 is discharged from the drain pipe 23. do.

When the water level in the water tank 19 drops to the water distribution port 30, water discharge from the drain pipe 23 stops and air flows into the water channel 31, causing the water channel 31 and the drain pipe 23 to flow.
water level decreases.

Next, open the automatic valve V ₄ and store the raw water in the water tank 19 up to the high water level A in the same manner as described above, close the automatic valve V ₄ based on the signal from the water level detector 25, and close the automatic valve V ₁ to reverse the operation. The washing siphon tube 5 is kept on standby for activation. Note that when water is supplied to the water tank 19 as described above, the water level in the water channel 31 rises again because the automatic valve V ₂ is closed, and the water level in the outer cylindrical pipe 29 rises again.
The air above the drain pipe 23 and inside the drain pipe 23 is pressurized.

If the above-mentioned washing is continued, the floor 6 will become clogged, so backwashing is performed.

In other words, at the beginning of the overflow period, the water level in the overflow pond 3 is almost the same as the water level in the overflow channel 9, but as the floor 6 becomes clogged, the water level in the overflow pond 3 gradually rises until the water level reaches the water level. It reaches B of the detector 26. When this is achieved, open the siphon stop automatic release valve V ₆ to introduce air into the siphon pipe 22 for water passage to stop the siphon, and then
Interrupting the inflow of raw water to.

Further, when the water sampling time set in advance by a timer (not shown) ends, the siphon stop automatic release valve _V6 may be opened to stop the water flow siphon pipe 22. If the inflow of raw water is interrupted, over pond 3
The water in the basin passes through the floor 6 and flows out from the overwater culvert 9, and the water level drops from B to C, which is slightly above the water level in the overwater culvert 9, and draining of the overwater culvert 3 is completed.

A water surface detector (not shown) is used to detect the end of water draining.
may be provided to detect that the water level has fallen to C, or the time for the water level to fall to C may be set in advance and detected using a timer (not shown).

After doing this, the backwashing siphon pipe 5 is started, but since the water tank 19 is filled with water as described above, the automatic valve V ₃ is closed and the automatic valve V ₁ is opened, and then the automatic valve Open _V2 .

In this way, the pressurized air in the outer tube 29 flows out from the air vent tube 28, the air pressure in the upper part of the outer tube 29 decreases, and the water in the water tank 19 flows through the water flow port 30 of the outer tube 29 and the water channel. 31 and then rapidly discharged from the drain pipe 23. As the water level in the water tank 19 decreases, the air in the backwashing siphon pipe 5 is sucked into the water tank 19 through the communication pipe 20, and the water level in the water tank 19 decreases.
Backwash wastewater inflow chamber 13 and backwash wastewater retention culvert 16
The air pressure in the backwashing siphon tube 5, which has been sealed with water, rapidly decreases, the water level inside the backwashing siphon tube 5 rises, and the siphon is activated.

Also, in the same way as the above-mentioned operation of the water flow siphon pipe, the automatic valve _V2 is immediately closed when water begins to drain from the water tank 19.

In this way, the water in the filter basin 3 is discharged from the backwash wastewater inflow chamber 13 through the backwash siphon pipe 5, the backwash wastewater retention culvert 16, and the backwash wastewater outflow culvert 18, and the water level in the backwash wastewater inflow chamber 13 is reversed. The water drops below the washing drain gutter 12. Also, during this time, overflow was being carried out in other overflow ponds, and the water level of overflow weir 9 was lower than that of overflow weir 1.
Since the height is kept constant at 1, the overwater culvert 9
Due to the water head difference between the water level and the upper edge of the backwash drain trough 12, excess water in the overwater drain 9 flows back from the overwater collection chamber 8 to backwash the floor 6, and the backwash wastewater flows through the backwash drain trough. 12 and flows into the backwash drainage inflow chamber 13 . In addition, the backwash wastewater flowing into the backwash wastewater inflow chamber 13 passes through the backwash siphon pipe 5 and is discharged from the backwash wastewater retention conduit 16 and the backwash wastewater outflow conduit 18 as described above, Backwashing of the floor 6 continues as the water level is maintained below the backwash drain trough 12 and above the water level of the backwash wastewater retention culvert 16.

Note that when the backwashing siphon pipe 5 is activated, the discharge of water from the drain pipe 23 of the water tank 19 is stopped, and the water surface in the water tank 19 becomes a low water level D.

Next, after backwashing for the specified time, automatic valve V ₁
Close the siphon stop automatic release valve _V3 , open the siphon stop valve V3, introduce air into the backwash siphon pipe 5 to stop the discharge of backwash wastewater, and start the water flow siphon pipe 22 again as described above to stop the siphon pipe 5. I do.

Note that when starting the water passing siphon tube 22 for the second time and thereafter, it may be started by discharging water from the water tank 19 as described above, but it can also be started by the following operation. can.

That is, as mentioned above, the backwashing siphon pipe 5
When the water tank 19 is started, the water level in the water tank 19 becomes constant at the low water level D, and the water tank 19 and the communication pipe 20 have residual negative pressure, and this residual negative pressure is utilized. In general, in normal gravity filtration equipment, the air capacity of the siphon pipe for water flow is much smaller than that for backwashing, and the H ₃
H ₁ is very small, so open the automatic valve V ₅ of the water siphon pipe 22 and remove the water siphon pipe 2.
2 is connected to the water tank 19 having a residual negative pressure and the communication pipe 20, the air inside the water-flowing siphon pipe 22 can be sucked and the siphon can be activated. In addition, the water tank 19 and the communication pipe 20 when starting the water flow siphon pipe 22 are, for example,
It has a negative pressure of 1.5 to 3 mH ₂ O, and this level of negative pressure is sufficient to start the water flow siphon tube 22 .

Furthermore, after starting the filtration as described above, immediately close the automatic valve _V5 of the water flow siphon pipe 22,
Then automatic valve V ₁ and siphon stop automatic release valve
V ₃ is opened and air is introduced into the backwashing siphon pipe 5 to stop the discharge of backwashing wastewater and to open the water tank 1.
9 is opened to the atmosphere, and the water in the water tank 19 is drained through the drain pipe 2.
3 and introduce the atmosphere into the outer cylindrical pipe 29, and then open the automatic valve _V4 in the same manner as described above to open the water tank 1.
Supply water into the siphon pipe 5 for the next backwash.
Wait until it starts.

The method for starting and stopping a siphon pipe for backwashing of the present invention is to discharge water from a water tank with a water head difference greater than the water head difference in the siphon pipe, suck air in the siphon pipe communicated with the water tank, and start the siphon. In addition, since this method opens the siphon stop automatic release valve and introduces air into the siphon pipe for backwashing to stop the siphon, there is no need for a special power source such as a vacuum pump, and it is possible to open a small diameter automatic valve. The siphon can be reliably started or stopped with a simple operation, and the siphon can be reliably started and stopped with a simple operation at low manufacturing cost.

Furthermore, by creating a unique structure inside the water tank, it is possible to eliminate the need to provide an automatic valve in the drain pipe 23, which has a relatively large diameter, and to open and close the automatic valve _V2 installed in the exhaust pipe, which has an extremely small diameter. The water can then be drained from the aquarium.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a self-cleaning gravity-type filtration device using a method for starting and stopping a backwashing siphon pipe according to an embodiment of the present invention, and FIG. It is an enlarged explanatory diagram. 1...Gravity filtration device, 2...Raw water inlet, 3...
Water pond, 4... Raw water distribution room, 5... Backwash siphon pipe, 6... Floor, 7... Support floor, 8... Super water collection room,
9... Overwater drain, 10... Overwater outflow drain, 11... Overflow weir, 12... Backwash drainage gutter, 13... Backwash drainage inlet chamber,
14... Partition wall, 15... Raw water inflow chamber, 16... Backwash wastewater retention culvert, 17... Water seal weir, 18... Backwash wastewater outflow culvert,
19... Water tank, 20... Communication pipe, 21... Supply pipe, 22
...Water flow siphon pipe, 23...Drain pipe, 24...Raw water pipe, 25...Water surface detection meter, 26...Water surface detection meter, 2
7... Water seal weir, 28... Exhaust pipe, 29... Outer cylinder pipe, 30
...Water outlet, 31...Waterway, V ₁ , V ₂ , V ₄ , V ₅ ...
Automatic valve, V ₃ , V ₆ ...Siphon stop automatic release valve.

Claims (1)

[Claims] 1 A filter basin 3 partitioned into a floor 6 and a backwash wastewater inflow chamber 13 by a partition wall 14, which is adjacent to the backwash wastewater inflow chamber 13 in a separated state and is lower than the water level at which backwash water from the floor 6 overflows. A backwash drainage retention culvert 16 that maintains a water level below, an overwater culvert 9 that communicates with the bottom of the floor 6 and maintains a water level above the water level at which backwash water from the floor 6 overflows, and a backwash drainage A backwash siphon consisting of an inverted U-shaped pipe that communicates the inflow chamber 13 and the backwash wastewater retention conduit 16 with a bent portion above the water level of the filter basin 3, and whose both ends are sealed with water. The water in the backwash drainage inflow chamber 13 is discharged by the backwash siphon pipe 5, and the water head held by the overwater culvert 9 causes the overwater to flow back to the floor 6. In the gravity type filtration device, when starting and stopping the backwashing siphon pipe 5, the water surface of the backwash wastewater inflow chamber 13 and the backwashing siphon pipe 5 when the backwashing siphon pipe 5 is about to be started. Distance from the top of H ₁
and the distance H ₂ between the low level water level in the water tank 19 and the water seal water level in the backwash drainage retention conduit 16 of the drain pipe 23 attached to the water tank 19, which will be described later, has a relationship of H ₁ < H ₂ . A sealed water tank 19 is installed, one end of the communication pipe 20 is connected to the water tank 19,
The other end of the communication pipe 20 is connected to the upper part of the backwashing siphon pipe 5 via an automatic valve _V1 , and an automatic valve
Communication pipe 20 between V ₁ and backwashing siphon pipe 5
Alternatively, a siphon stop automatic release valve V ₃ is provided at the upper part of the backwashing siphon pipe 5, and a water surface detector 25 is provided in the water tank 19 to detect a high level water level in the water tank 19, and the water surface detector 25 is linked to the water surface detector 25. A supply pipe 21 having an automatic valve V ₄ is connected to the water tank 19, and its lower end is sealed with the water surface of the backwash wastewater retention conduit 16, and its upper end is passed through the water tank 19 and connected to the water tank 19.
A drain pipe 23 opened inside is provided, and a water flow port 30 is provided which has a larger inner diameter than the drain pipe 23 and is located below the opening of the drain pipe 23 in the water tank 19.
The outer cylindrical tube 29 with a sealed upper part is placed in the water tank 19.
It is fixed in the water tank 19 so as to cover the inner drain pipe 23, and an exhaust pipe 28 having an automatic valve _V2 is connected to the upper part of the outer cylinder pipe 29, and the capacity of the water tank 19 is When the water is discharged from the drain pipe 23 from the high water level to the low water level, the air inside the backwashing siphon pipe 5 and the communication pipe 20 is sucked, thereby reducing the inside of the backwashing wastewater inflow chamber 13. The water is sucked up to a capacity that drives the backwashing siphon pipe 5, the automatic valve _V1 and the siphon stop automatic release valve _V3 are opened to open the water tank 19 to the atmosphere, and the automatic valve _V4 is opened to open the water tank. 1
9, and when the water level reaches the above-mentioned high level, close the automatic valve _V4 and close the siphon stop automatic release valve _V3 , then open the automatic valve _V2 while keeping the automatic valve _V1 open. Activation of the backwashing siphon pipe 5 by opening the water tank 19 and discharging the water in the water tank 19 from the drain pipe ₂₃ according to the water head difference, and then immediately closing the automatic valve V 2 to start the backwashing siphon pipe 5; Close valve V ₁ siphon stop automatic open valve
Backwash siphon tube 5 activated by opening V ₃
A method for starting and stopping a backwashing siphon tube 5 of a gravity-type filtration device, characterized by sequentially repeating the steps of stopping the backwashing siphon tube 5.