JPH0255086B2 - - 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 the siphon of 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, but the power source However, there is a disadvantage that an expensive vacuum pump and pressure water pump for the ejector must be provided.

It is an object of the present invention to compensate for these conventional drawbacks, and to reliably start and stop a backwash siphon pipe without requiring a special power source, at low production cost, and with simple operation.

That is, the present invention includes a plurality of filter basins 3 which are partitioned by a partition wall 14 into a floor 6 and a backwash wastewater inflow chamber 13, and which are installed adjacent to and separated from the backwash wastewater inflow chamber 13, so that the backwash water of the floor 6 is separated from the backwash wastewater inflow chamber 13. A common backwash drainage retention conduit 16 that maintains the water level below the water level at which the backwash water overflows and communicates with the bottom of the floor 6 and maintains the water level above the water level at which the backwash water in the floor 6 overflows. The common overwater drain 9, each backwash wastewater inflow chamber 13, and the common backwash wastewater retention drain 16 are connected to each other by having a bent portion above the water level of the overwater basin 3, and both ends thereof are It consists of at least a plurality of backwashing siphon tubes 5 consisting of sealed inverted U-shaped tubes,
In a gravity-type filtration device in which the water in the backwash drainage inlet chamber 13 is discharged through a backwash siphon pipe 5 and the excess water is caused to flow back to the floor 6 by the water head held by the overflow conduit 9, backwashing is performed. Distance H ₁ between the water surface of the backwashing wastewater inflow chamber 13 and the top of the backwashing siphon pipe 5 when trying to start the backwashing siphon pipe 5
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 suction/drainage pipe 23 attached to the water tank 19 has a relationship of H ₁ <H ₂ , and The distance _H5 between the high level water level and the water seal water level of the suction and drainage pipe 23, and the distance _H4 between the upper part of the backwashing siphon pipe 5 and the water surface of the backwashing wastewater retention conduit 16 are such that _H5 < _H4 A sealed water tank 19 is installed in such a manner that the upper part of each backwashing siphon pipe 5 and the water tank 19 are connected through a common communication pipe 20, and the connection pipe 20 is connected to the one closest to the water tank 19. A common automatic valve V ₂ , a common siphon stop automatic release valve V ₃ , and an automatic valve V ₁ for each backwash siphon pipe are provided in this order, and a water stop valve consisting of an automatic valve or a manual valve is installed in the suction/discharge pipe 23. V ₆ is provided, and the water tank 19 is provided with a supply pipe 21 having an inflow valve V ₅ consisting of an automatic valve or a manual valve, and the water tank 19 is further provided with a water level detector 25 for detecting a high level water level in the water tank 19, The water surface detection meter and the automatic valve V ₂ are linked, and the capacity of the water tank 19 is reduced by backwashing when the water in the water tank 19 is discharged from the water intake and drainage pipe 23 from the high water level to the low water level. By suctioning the air present inside the backwashing siphon pipe 5 and the communication pipe 20, the water in the backwashing wastewater inflow chamber 13 is sucked up to create a capacity that allows the backwashing siphon pipe 5 to start. When starting and stopping one of the siphon pipes 5 for washing, when starting the siphon pipe 5 for backwashing for the first time, close the water stop valve V ₆ and,
Open the automatic valve V ₂ , the siphon stop automatic release valve V ₃ , and the inflow valve V ₅ to fill the water tank 19 with water.
When the water level reaches the high water level, the inflow valve V ₅ and the siphon stop automatic release valve V ₃ are closed, and then the automatic valve V ₁ and the automatic valve V ₂ of the backwashing siphon pipe 5 to be started, By opening the water stop valve V ₆ and closing the automatic valve V ₁ of the other backwashing siphon pipe 5 to discharge the water in the water tank 19 from the suction and drainage pipe 23 with a difference in water head, the backwashing siphon pipe 5 is closed. 5, and also open the automatic valve V ₁ , automatic valve V ₂ , and water stop valve V ₆ of the backwash siphon pipe 5 that are activated even after the start, and water is generated in the upper part of the backwash siphon pipe 5. Water is sucked up from the suction and drainage pipe 23 by negative pressure, and when the water level reaches the high level water level, the automatic valve V ₂ is closed to retain the water in the water tank 19.
The water inside is used as starting water for the next backwashing siphon pipe 5, and the automatic valve V ₁ and siphon stop automatic release valve V ₃ of the backwashing siphon pipe 5 are activated at the same time as the automatic valve V ₂ is closed. When opening the siphon stop valve V3 to stop the backwashing siphon pipe 5, and then starting the backwashing siphon pipe 5 next time, close the siphon stop automatic release valve _V3 and open the siphon pipe 5 for backwashing to be started. Open automatic valve V ₁ and automatic valve V ₂ ,
Then, the automatic valve V ₁ of the other backwashing siphon pipe 5 is closed, and the water in the water tank 19 sucked up from the suction and draining pipe 23 is discharged according to the water head difference, thereby starting the backwashing siphon pipe 5. The automatic valves V ₁ and V ₂ of the activated backwashing siphon pipe 5 are opened, and water is sucked up from the suction and drainage pipe 23 by the negative pressure generated in the upper part of the backwashing siphon pipe 5, and the water level reaches the above level. Automatic valve when water level reaches high level
Close V ₂ to retain water in the water tank 19, and transfer the water in the water tank 19 to the siphon pipe 5 for backwashing from next time onwards.
After that, it is used as starting water for the next backwashing siphon pipe 5 and for starting the backwashing siphon pipe 5.
The present invention relates to a method for starting and stopping a backwashing siphon tube of a gravity-type filtration device, which is characterized by sequentially repeating the following steps:

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

The drawing is a longitudinal cross-sectional explanatory view showing an example of an embodiment of a gravity-type filtration device using the self-starting and stopping method of a backwashing siphon pipe according to the present invention. A plurality of over ponds 3 are provided in a row, and a raw water inflow conduit 2 common to each over pond 3 is provided above the over 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 raw water inflow chamber 15 is provided outside the raw water distribution chamber 4 via a water seal weir 27. A plurality of water flow siphon pipes 22 connect each raw water distribution chamber 4 and raw water inflow conduit 2.
(for convenience, siphon tube 2 for water flow)
2 shows only one unit. ). 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 each of the chambers 13 and each of the raw water inflow chambers 15 are communicated through a plurality of raw water pipes 24. In addition, a support bed 7 is provided below the other chamber of each overpass pond 3, and a floor 6 is formed above the support bed 7.
A plurality of backwash drainage troughs 12 are provided above the floor 6 and at the height of the upper end of the partition wall 14, and one end of the backwash drainage troughs 12 on the partition wall 14 side is opened. In addition, an overwater collection chamber 8 is provided below the support bed 7, and this chamber 8 is further connected to a common overwater conduit 9, so that overwater flowing out from each overwater basin 3 is passed through the overwater collection chamber 8 to the common overwater collection chamber 8. It joins the overflow ditch 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. Additionally, a water surface detector 26 is attached to the over pond 3.

In addition, a common 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 each filter basin 3 are connected to each other. The backwashing siphon pipes 5 are connected by a plurality of backwashing siphon pipes 5 which are inverted U-shaped pipes having a bent part above the water level of the pond 3 and having both ends sealed with water (for convenience, the backwashing siphon pipes 5 are one (Only the base is shown.) Further, a backwash wastewater outflow culvert 18 is provided further outside the backwash wastewater retention culvert 16, and a water seal weir 17 having a height lower than the partition wall 14 is provided between the backwash wastewater retention culvert 16 and the backwash wastewater outflow culvert 18. communicate through
The water level of the backwash drainage retention conduit 16 is kept constant at the height of the water seal weir 17.

In addition, the sealed water tank 19 is backwashed to the waste water retention conduit 16.
Distance H ₁ between the water surface of the backwash wastewater inflow chamber 13 and the upper part of the siphon pipe when the backwash siphon pipe 5 is to be started, and the low level in the water tank 19 as will be described later. The distance _H2 between the water level D and the water surface of the backwash wastewater retention conduit 16 has a relationship of _H1 < _H2 , and the high level water level A in the water tank 19
and the distance H ₅ from the water seal water level of the suction and drainage pipe 23, which will be described later.
and the distance H ₄ between the upper part of the backwashing siphon pipe 5 and the water surface of the backwashing wastewater retention conduit 16 are provided so that H ₅ <H ₄ . Note that the capacity of the water tank 19 will be described later. Further, in this embodiment, water from the raw water inflow conduit 2 is used as the water for starting the siphon pipe for the first time, but the water is not limited to this, and other water may be used. Further, a water-tight water-sealing pipe 23 is provided below the water tank 19, which has a water stop valve V ₆ consisting of an automatic valve or a manual valve, and has a lower end opened below the water surface of the backwash drainage retention conduit 16 and is water-sealed. The diameter of the suction/drainage pipe 23 is such that the water in the water tank 19 can be rapidly discharged and the backwash waste water can be transferred to the water tank 19 in a short time.
The thickness should be such that it can absorb 6 of the water.

Also, one end of a common communication pipe 20 is connected to the upper part of the water tank 19, and the other end is branched and connected to the upper part of each backwashing siphon pipe 5, and each backwashing siphon pipe 5 is connected to the communication pipe 20. An automatic valve V ₁ is installed in the Furthermore, a common siphon stop automatic release valve V 3 is provided in the communication pipe 20 between the water tank 19 and each automatic valve V ₁ , and a common siphon stop automatic release valve V ₃ is provided in the communication pipe 20 between the siphon stop automatic release valve V ₃ and the water tank 19. Automatic valve _V2 will be installed. In addition, as shown in the drawing, there is a communication pipe 2 between the siphon stop automatic release valve V ₃ and each automatic valve V ₁ .
0 may be branched and connected to the upper part of each water flow siphon pipe 22 via an automatic valve _V4 .

In addition, a water surface detection meter 25 is provided in the water tank 19, and an automatic valve _V2 is linked to the water surface detection meter 25.
When the water surface reaches the high water level A, the automatic valve V ₂ linked to the water surface detector 25 closes, and the water intake and drainage pipe 23 closes.
Configure it so that it stops drawing water from it.
In addition, the water tank 19 and the raw water inlet 2 are connected via a supply pipe 21 having an inlet valve _V5 consisting of an automatic valve or a manual valve, but as mentioned above, the raw water in the raw water inlet 2 is used as the initial start-up water of the siphon pipe. Needless to say, when water other than the above is to be filled, the other end of the supply pipe 21 is communicated with the supply source.

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 air having the capacity of the water tank 19 from water levels A to D is sucked inside the backwashing siphon pipe 5 and the communication pipe 20. When the water in the water tank 19 is discharged through the suction/drainage pipe 23 with a water head difference, while the water level reaches from A to D, the backwash siphon pipe 5 Configure it to start. When carrying out filtration in such a filtration device 1, the siphon pipe 22 for water flow is first activated, but as shown in the drawing, the other end of the communication pipe 20 is branched and the water flow is carried out via the automatic valve _V4 . When communicating with the upper part of the siphon tube 22, the water tank 19 used in the present invention
By using the water flow siphon pipe 22
can be started.

That is, the water stop valve V ₆ of the suction and drainage pipe 23 is closed, the automatic valve V ₂ and the siphon stop automatic release valve V ₃ are opened, and the inflow valve V ₅ of the supply pipe 21 is opened to supply water to the water tank 19 from the raw water inflow conduit 2. As a result, raw water will be supplied. When the water level of the water tank 19 rises to the high water level A, the inflow valve _V5 is closed and the supply of raw water is stopped. Also, after stopping the supply of raw water, close the siphon stop automatic release valve _V3 .

Next, when automatic valve V ₄ and water stop valve V ₆ of water flow siphon pipe 22 are opened, automatic valve V ₂ is opened by the above-mentioned operation.
Since the water tank 19 remains open, the water in the water tank 19 is rapidly discharged from the suction and drainage pipe 23, and the water in the water tank 19 is
As the water level inside decreases, the air inside the water siphon pipe 22 is sucked into the water tank 19 through the communication pipe 20, and the water siphon pipe 22 is sealed by the raw water inflow conduit 2 and the raw water distribution chamber 4. The air pressure suddenly decreases, the water level in the water-flowing siphon tube 22 rises, and the siphon is activated. 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, and then into the raw water inflow chamber 15.
Further, the raw water flows into the backwash wastewater inflow chamber 13 of the overwater basin 3 through the raw water pipe 24, passes over the partition wall 14 and passes through the floor 6 in a downward flow, and the overwater flows into the overwater collection chamber 8, the overwater drain 9, and the overwater drainage channel 9. It flows out through an outflow culvert 10.

The water flow siphon pipe 22 has a smaller air capacity, for example, about 1/12, compared to the backwashing siphon pipe 5, and the air capacity on the inflow side when trying to start the water flow siphon pipe 22 is small. The distance H ₃ between the water surface and the upper part of the water passage siphon pipe 22 is much smaller than H ₁ in a normal gravity-type filtration device, and there is a relationship of H ₃ ≪ _{H 2} . By rapidly discharging the water, the water flow siphon pipe 22 can be easily activated.

On the other hand, when the water flow siphon pipe 22 is activated, the water discharge from the water intake and drainage pipe 23 of the water tank 19 is stopped.
The water level in the water tank 19 remains constant. Next, water stop valve V ₆
and close the automatic valve V ₄ , open the siphon stop automatic release valve V ₃ , and further open the inflow valve V ₅ to store raw water in the water tank 19 up to the water level A as described above,
Close the inflow valve V ₅ and open the siphon pipe 5 for the first backwash.
Wait until it starts.

If such filtration continues, the floor 6 will become clogged, so backwashing is performed. In other words, at the beginning of the overflow, the water level in the overflow basin 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 basin 3 gradually rises, and the water level is detected. Reach a total of 26 B's. When this happens, the siphon stop automatic release valve V ₃ is already open, so open the automatic valve V ₄ to introduce air into the water flow siphon pipe 22 and interrupt the flow of raw water into the sieve pond 3. do. Furthermore, when the water sampling time set in advance by a timer (not shown) ends, the automatic valve _V4 may be opened to stop the water flow siphon pipe 22. If the inflow of raw water is interrupted, over pond 3
The water passes through the floor 6 and flows out from the overwater drain 9,
The water level drops from B to C, which is slightly above the water level of the overwater channel 9, and draining of the water from the overwater channel 3 is completed.

A water surface detector (not shown) is used to detect the end of water travel.
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 first backwashing siphon tube 5
In this case, the automatic valve V ₄ of the water flow siphon pipe 22 and the siphon stop automatic release valve V ₃ are activated.
, open the automatic valve V ₁ and water stop valve V ₆ of the backwashing siphon pipe 5 to be started, and close the automatic valve V ₁ of the other backwashing siphon pipe 5 to drain the water in the water tank 19. is rapidly discharged from the suction and drainage pipe 23.
Note that automatic valve V ₂ remains open from the previous process. As the water level in the water tank 19 decreases, the air in the backwash siphon pipe 5 is sucked into the water tank 19 through the communication pipe 20, and the air is sucked into the water tank 19 through the communication pipe 20, and the air is sucked into the water tank 19 through the backwash wastewater inflow chamber 13 of the filter basin 3 and the backwash wastewater retention conduit 16. The air pressure in the backwashing siphon tube 5, which is sealed with water, rapidly decreases, the water level inside the backwashing siphon tube 5 rises, and the siphon is activated. In this way, the water in the filter basin 3 is transferred from the backwash wastewater inflow chamber 13 to the backwash siphon pipe 5.
After that, backwash wastewater retention pipe 16, backwash wastewater outflow pipe 1
8, and the water level in the backwash drainage inlet chamber 13 drops below the backwash drainage gutter 12.

Also, during this time, filtration is being carried out in other overwater basins, and the water level in overwater culvert 9 is kept constant at the height of overflow weir 11. Due to the water head difference with the edge, excess water in the excess water channel 9 flows back from the excess water collection chamber 8 to the floor 6.
Backwashing is performed, and the backwash wastewater flows into the backwash wastewater inflow chamber 13 from the backwash drainage gutter 12. In addition, the backwash wastewater flowing into the backwash wastewater inflow chamber 13 passes through the backwash siphon pipe 5, and then flows into the backwash wastewater retention conduit 16 as described above.
and backwash drainage from drain culvert 18, and the corresponding room 1
3 is maintained below the backwash drainage gutter 12 and above the water level of the backwash drainage retention culvert 16, so that the floor 6 is continuously backwashed.

On the other hand, when the backwashing siphon pipe 5 is activated, the water discharge from the suction and discharge pipe 23 of the water tank 19 is stopped.
The water surface in the water tank 19 temporarily becomes a low water level D. However, if automatic valve V ₁ , automatic valve V ₂ , and water stop valve V ₆ are left open after that, the activation of backwash siphon pipe 5 causes a 4 to 5 m. Since a negative pressure of H ₂ O is generated, the air in the water tank 19 can be sucked into the backwashing siphon pipe 5 through the communication pipe 20.
In addition, as the air is sucked, the backwash wastewater in the backwash wastewater retention conduit 16 is sucked up into the water tank 19 through the suction and drainage pipe 23, and the water level in the water tank 19 rises. level water level A
Automatic valve V ₂ closes automatically when the temperature rises to . In this way, while the backwashing siphon pipe 5 is activated for the first time, the negative pressure generated in the upper part of the backwashing siphon pipe 5 is used to suck up the backwash wastewater from the backwash wastewater retention conduit 16 into the water tank 19 and tension it. Therefore, it is only necessary to supply make-up water such as raw water to the water tank 19 only when starting up the backwashing siphon pipe 5 for the first time, and it is necessary to supply makeup water such as raw water to the water tank 19 only when starting up the backwashing siphon pipe 5 for the first time. There is no need to separately secure
In addition, the amount of water discharged from the backwash drainage retention conduit 16 does not increase, and the switching operation of the inflow valve V ₅ and the water stop valve V ₆ for charging water into the water tank 19 only requires the initial activation of the siphon pipe. After that, basically, the backwash siphon pipe can be started only by operating automatic valves _V1 and _V2 . In addition, when starting each siphon from the next time onwards, the inflow valve _V5 is basically always closed, and the water stop valve _V6 is always open.

Next, after backwashing has been performed for a predetermined period of time, the backwashing siphon pipe 5 is stopped, but before that, the water flow siphon pipe 22 may be activated to start water flow. In other words, in a normal gravity filtration device, the siphon tube for water flow is more efficient than the siphon tube for backwashing.
The air capacity of the siphon is much smaller and
Since H ₃ is much smaller than H ₁ , by opening the automatic valve V ₄ of the siphon pipe 22 for water flow, the water is passed to the communication pipe 20 that has the residual negative pressure generated by starting the siphon pipe 5 for backwashing. Simply by suctioning the air inside the water siphon tube 22, the water level in the water siphon tube 22 can be raised to easily start the siphon, and filtration can be started. In addition, the communication pipe 2 when starting the water flow siphon pipe 22
0 has a residual negative pressure of, for example, 1.5 to 3 m·H ₂ O, and such negative pressure is sufficient to start up.
When the automatic valve V ₁ is opened, the air in the water flow siphon pipe 22 is sucked by the negative pressure generated at the upper part of the backwashing siphon pipe 5, and the water flow siphon pipe 22 is easily activated. be able to.

After starting the filtration, immediately close the automatic valve _V4 of the water flow siphon pipe 22, then open the automatic valve _V1 of the backwashing siphon pipe 5 and the siphon stop automatic release valve _V3 , which are activated. Air is introduced into the backwash siphon pipe 5 to stop the discharge of backwash wastewater.

After the filtration has been carried out for a predetermined period of time, backwashing is carried out again, but first, as mentioned above, the automatic valve _V4 of the water flow siphon pipe 22 is opened, and the siphon, which was in the open state in the previous process, is automatically opened. Air is introduced into the water flow siphon pipe 22 through the valve _V3 to interrupt the flow of raw water.

The next activation of the backwashing siphon tube 5 is performed as follows.

i.e. close the siphon stop-open automatic valve V ₃ ,
Open the automatic valves V ₁ and V ₂ of the backwashing siphon pipe 5 to be activated, close the automatic valve V ₁ of the other backwashing siphon pipe 5, and then start the first backwashing siphon pipe described above. Water tank 1 sucked up when starting up
The water in 9 is discharged by the difference in water head.

As the water level in the water tank 19 decreases, the air in the backwash siphon pipe 5 is sucked into the water tank 19 through the communication pipe 20, and the air is sucked into the water tank 19 through the backwash wastewater inflow chamber 13 and the backwash wastewater retention conduit 9. The water level in the water-sealed backwashing siphon pipe 5 rises and the siphon is activated.

In addition, after the siphon is started, if the automatic valves V ₁ and V ₂ are left open, the backwash siphon pipe 5 will be started, in the same way as the initial activation of the backwash siphon pipe 5 described above. Due to the negative pressure generated in the upper part of the siphon pipe 5, the backwash wastewater in the backwash wastewater retention conduit 16 is sucked up into the water tank 19 through the suction and drainage pipe 23.

Further, the water level of the water sucked into the water tank 19 rises to the high water level A, but at this point, the automatic valve _V2 closes and the flow of water into the water tank 19 is automatically stopped.

The water sucked into the water tank 19 in this manner can be used as starting water for the backwashing siphon pipe 5 from the next time onwards.

The method for starting and stopping the backwashing siphon pipe of the present invention is to discharge water from the water tank with a water head difference that is larger than the water head difference in the backwashing siphon pipe, and to suck air in the backwashing siphon pipe that communicates with the water tank. This method does not require a special power source such as a vacuum pump, and is a small and compact method. The siphon can be reliably started or stopped simply by opening and closing an automatic valve of the same diameter, and the backwash siphon pipe can be reliably started and stopped with simple operation at low manufacturing costs.

In addition, filling water into the water tank 19 requires external water for the first activation of the backwashing siphon pipe, but from the next time onwards, the negative pressure generated by the activation of the backwashing siphon pipe is used to suck and drain water. water pipe 2
Since the water can be sucked up into the water tank through step 3, there is no need to increase the amount of water discharged from the water tank.

Further, when the water flow siphon pipe 22 is branched and communicated with the communication pipe 20 used in the present invention, an automatic valve
It can be started easily by simply switching V ₄ , and there is no need to separately install a siphon stop automatic release valve to stop the water flow siphon pipe, and the siphon stop automatic release valve of the backwash siphon pipe 5 can be started easily. Valve V ₃ can be used to stop the siphon.

[Brief explanation of the drawing]

The figure 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. 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...Suction and drainage pipe, 24...
Raw water pipe, 25... Water surface detection meter, 26... Water surface detection meter,
27...Water seal weir, _V1 , _V2 , _V4 ...Automatic valve, _V3 ...Siphon stop automatic release valve, _V5 ...Inflow valve, _V6 ...Water stop valve.

Claims (1)

[Claims] 1 A plurality of filter basins 3 are partitioned into a floor 6 and a backwash wastewater inflow chamber 13 by a partition wall 14, and are installed adjacent to and separated from the backwash wastewater inflow chamber 13, so that the backwash water in the floor 6 overflows. a common backwash drainage retention conduit 16 that maintains a water level below the water level where the backwash water from the floor 6 overflows; The water channel 9, each backwash wastewater inflow chamber 13, and the common backwash wastewater retention channel 16 are communicated with each other by having a bent part above the water level of the filter basin 3, and both ends thereof are water-sealed. The water in the backwash wastewater inflow chamber 13 is discharged by the backwash siphon pipes 5,
In a gravity-type filtration device in which excess water is caused to flow back to the floor 6 by the water head held by the excess water conduit 9, the water surface of the backwash wastewater inflow chamber 13 when trying to start the backwash siphon pipe 5 and , the distance H ₁ from the top of the backwashing siphon pipe 5, the low level water level in the water tank 19, and the suction and drainage pipe 23 attached to the water tank 19.
Distance from water seal water level in backwash drainage retention conduit 16
H ₂ has a relationship of H ₁ < H ₂ , and the water tank 19
The distance H ₅ between the high level water level in the interior and the water seal water level of the suction and drainage pipe 23, and the distance H ₄ between the upper part of the backwash siphon pipe 5 and the water surface of the backwash wastewater retention conduit 16 are H ₅
A sealed water tank 19 is installed so that the _relationship of In order from the one closest to the common automatic valve V ₂ , the common siphon stop automatic release valve V ₃ , and the automatic valve for each backwash siphon pipe.
V ₁ is provided, further a water stop valve V ₆ consisting of an automatic valve or a manual valve is provided in the suction/discharge pipe 23, and a supply pipe 21 having an inlet valve V ₅ consisting of an automatic valve or a manual valve is provided in the water tank 19; A water surface detection meter 25 in the water tank 19 that detects a high level water level in the water tank 19
was provided, the water level detector and the automatic valve _V2 were linked, and the capacity of the water tank 19 was adjusted so that the water in the water tank 19 was discharged from the suction and drainage pipe 23 from the high water level to the low water level. At times, by suctioning the air present inside the backwashing siphon pipe 5 and the communication pipe 20, the water in the backwashing drainage inflow chamber 13 is sucked up and the capacity is set such that the backwashing siphon pipe 5 is started. In starting and stopping one of the plurality of backwashing siphon tubes 5,
When starting the siphon pipe 5 for backwashing for the first time, close the water stop valve V ₆ and open the automatic valve V ₂ , the siphon stop automatic release valve V ₃ , and the inflow valve V ₅ to drain the water into the water tank 19. Water is filled in, and when the water level reaches the high water level, the inflow valve V ₅ and the siphon stop automatic release valve V ₃ are closed, and then the automatic valve V ₁ of the backwashing siphon pipe 5 to be started,
By opening the automatic valve V ₂ and the water stop valve V ₆ and closing the automatic valve V ₁ of the other backwashing siphon pipe 5, the water in the water tank 19 is discharged from the suction and drainage pipe 23 with a head difference. The backwashing siphon pipe 5 is started, and the automatic valve V ₁ , the automatic valve V ₂ , and the water stop valve V ₆ of the backwashing siphon pipe 5 which are activated even after starting are opened, and the backwashing siphon pipe 5 is started. Water is sucked up from the suction and drainage pipe 23 by the negative pressure generated in the upper part of the water tank 19, and when the water level reaches the above-mentioned high level, the automatic valve _V2 is closed to retain the water in the water tank 19. Use the water as starting water for the next backwashing siphon pipe 5,
In addition, when the automatic valve V ₂ is closed, the automatic valve V ₁ of the siphon pipe 5 for backwashing, which is activated, and the siphon stop automatic release valve V ₃ are opened, and the siphon pipe 5 for backwashing is opened.
Stop the siphon pipe 5 for the next backwash.
Automatic release valve stops the siphon when starting
Close V ₃ , open automatic valves V ₁ and V ₂ of the backwashing siphon pipe 5 to be activated, close the automatic valve V ₁ of the other backwashing siphon pipe 5 , and then The backwashing siphon pipe 5 is activated by discharging the sucked up water in the water tank 19 according to the water head difference, and the automatic valves V ₁ and V ₂ of the backwashing siphon pipe 5 which are activated even after activation are activated. Open,
Water is sucked up from the suction and drainage pipe 23 by the negative pressure generated in the upper part of the backwashing siphon pipe 5, and when the water level reaches the above-mentioned high level, the automatic valve _V2 is closed to retain the water in the water tank 19. The water in the water tank 19 is used as starting water for the backwashing siphon pipe 5 from the next time onward, and thereafter, the starting of the next backwashing siphon pipe 5 and the stopping of the backwashing siphon pipe 5 are sequentially repeated. A method for starting and stopping a siphon tube for backwashing in a gravity-type filtration device.