JPH0621525Y2 - Continuous sand filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a continuous sand filter.

(Prior Art) As sand filters used in the treatment of sewage and wastewater, there are pressure sand filters and continuous sand filters for the purpose of rapid filtration. Although the pressure type can satisfactorily perform filtration, it has a drawback that the operation is complicated and the treatment capacity is low because the operation is intermittent because filtration and sand washing are performed alternately. In addition, the continuous type is a system that circulates the filtered sand by an air lift to wash the sand at the same time as the filtration, and has the advantage that continuous filtration is possible, but it is difficult to wash and separate the filtered sand. However, it has a drawback that good filtration cannot be performed.

Therefore, the applicant of the present invention relates to a continuous sand filter device for circulating filtered sand by an air lift, and discloses an application in Japanese Patent Application No. 59-6121.
We have been trying to improve it with No. 1 etc. This equipment has a sand reservoir on the top of the filtration tank to temporarily store the sand flowing out from the sand raising pipe, and intermittently backwash the stored sand by opening and closing the discharge opening of the sand reservoir. While returning to the filtration layer.

(Problems to be solved by the invention) In the improved device described above, since the filter sand is washed in the sand lifting process by the air lift, and is backwashed with the filter water when the filter sand falls, The separation is now well done.

However, in the improved device described above, since the filter sand is washed with the filter water, when the quality of the filter water is deteriorated, the mixed liquid in the filter tube is not filtered even if the air lift sand load is increased. Since it is close to that of raw water, not only the cleaning effect is not improved, but also the cross-section of the washed sand falling into the tank is small, so there is a problem that the amount of lifted sand cannot be greatly increased.

The present invention has been made to solve the above problems, and has a good backwashing effect on the filtered sand flowing out from the sand lifting pipe, which can further improve the filtering performance and the amount of air for increasing the backwashing effect. Even if the amount of water is increased, the amount of backwash water and hence the amount of discharged filtered water can be kept constant, it is possible to cope with wide fluctuations in water quality, and it is intended to provide a continuous sand filtration device that can further improve filtration performance. Is.

(Means for Solving the Problems) The structure of the present invention for achieving the above object will be described with reference to the drawings corresponding to the embodiments.
Filtration tank 1 with sand lifting pipe 5 by air lift standing in the center
In the upper part of the above, provided is a separation chamber 4 for filtering sand and drainage, in which the upper part of the sand lifting pipe 5 is projected, and it is connected to the bottom of the separation chamber 4 to enclose the sand lifting pipe 5 and to send an air pipe 12 to the lower part. A long sand washing drop pipe 8 connected to the above is provided, and a pressure tank 13 which surrounds the upper end of the sand lifting pipe 5 and whose lower end is opened is provided in the separation chamber 4 so as to be adjustable up and down, and the filtration tank 1 A weir plate 16 is provided between the discharge pipe 15 provided at the upper part and the pressure tank 13, and a pressure chamber 18 having an open lower end is formed across the weir plate 16 to form the pressure chamber 18 and the pressure tank. It is characterized in that the upper part of each of the parts 13 and 13 communicates with each other.

(Operation) In the filtering device configured as described above, the raw water is supplied to the inflow pipe 7
Then, it passes through the filtration layer a to become clear filtered water, which is taken out of the tank 1 through the outflow pipe 15. The sand in the filtration layer rises in the pipe from the lower end of the sand raising pipe 5 by the air lift action, and is washed by the flow of air and water during that time. The filtered sand that has come out from the upper end of the sand lifting pipe 5 falls through the washed sand drop pipe 8 and comes out from the lower end thereof and returns to the filtration layer. At that time, the filtered sand is purified by the action of removing and separating the washed sand and the adhered contaminants due to the gas-solid collision due to the rise of the air bubbles blown into the lower portion of the washed sand drop tube 8.

Further, the wash water and contaminants (dirt water) flowing out from the upper end of the sand lifting pipe 5 are discharged from the separation chamber to the outside of the tank through the discharge pipe 15 over the barrier plate. Then, the air discharged from the upper end of the sand lifting pipe 5 pressurizes both the pressure tank 13 and the pressure chamber 18, so that the pressure tank 13 and the pressure chamber 18 have the same amount of outflow air from the sand lifting pipe 5. Regardless of the water level, the water level will be kept almost constant. Therefore, even if the amount of air sent to the lifting sand pipe is increased to increase the amount of lifted sand, the drainage will be kept almost constant, and it is possible to change the sand washing effect and respond to fluctuations in water quality. it can. If the position of the pressure tank 13 is adjusted up and down, the water level c and the water level d of the pressure chamber 3 change, and the dam plate 1
The overflow of 6 or the amount of drainage can also be adjusted.

Embodiment An embodiment of the device of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 is a vertically long filtration tank, and a filtered water outflow pipe 3 is provided in an upper portion thereof through an overflow groove 2. Further, in the upper part of the filtration tank 1, a separation chamber 4 for filtering sand and washing water, the upper end of which is formed higher than the outflow water level a of the filtered water, is provided with the upper part open. 5 is a sand lifting pipe that is erected in the center of the filtration tank 1, its lower end has a required distance from the tank bottom, and its upper end is opened at the upper part of the separation chamber 4,
An air supply pipe 6 communicating with an air supply source (not shown) outside the tank 1 is connected to a lower portion of the sand lifting pipe 5. The raw water flow pipes 7, 7 are inserted into the lower portion of the filtration tank 1.

At the bottom of the separation chamber 4, the upper end of the vertically long sand washing drop pipe 8 arranged surrounding the sand lifting pipe 5 is connected, the upper end of the sand washing drop pipe 8 is connected, and the upper end of the washing sand drop pipe 8 is An opening is provided above an umbrella-shaped spreading plate 9 provided in the middle part of the sand lifting pipe 5.
In addition, a large number of fumaroles 10 and 10 are provided in the lower part of the sand washing drop pipe 8 along the circumference of the pipe, and these fumaroles 10 and 10 are connected to an air distribution pipe 11 connected to an air feeding pipe 12. There is.

Further, in the separation chamber 4, the pressure tank 13 which surrounds the upper part of the sand lifting pipe 5 and whose lower end is opened has its lower end positioned considerably lower than the upper end of the sand lifting pipe 5 and can be lifted and lowered by the lifting mechanism 14. It is provided in. In addition, an upper end of the drain pipe 15 is provided at an intermediate portion between the pressure tank and the drain pipe 15 of the wash water, which is provided at a position considerably lower than the overflow groove 2 on the upper part of the bath 1 facing the overflow groove 2. A weir plate 16 is provided at substantially the same height as the above, and thereby an overflow chamber 17 is formed between the discharge pipe 15 and the weir plate 16. And, straddling the upper part of the barrier plate 16,
A weir pressure chamber 18 having an open lower end is provided, and the pressure tank 13
The upper portions of the weir pressure chambers 13 and 18 are connected to each other by a ventilation pipe 19.

In the above apparatus, the filtration sand is formed in the tank 1 at a height up to the position below the spreading plate 9 to form a filtration layer.
Then, the raw water flows into the lower part of the tank 1 through the inflow pipes 7 and 7, rises in the filtration layer, removes contaminants and becomes clear filtered water, overflows into the overflow groove 2 in the upper part, and the outflow pipe. It is taken out of the tank from 3. The filtered sand in the filtration layer that has captured the contaminants is introduced from the lower end of the sand lifting pipe 5 by the air lift action of the air blown into the sand lifting pipe 5 from the air supply pipe 6
The liquid is transferred upward and flows into the separation chamber 4 from the upper end of the pipe 5. At this time, since sand, water, and air rise at different speeds in the sand lifting pipe 5, the contaminants adhering to the sand are separated and washed.

The sand that has flowed into the separation chamber 4 should enter the sand washing drop pipe 8 from the bottom of the separation chamber 4 due to its own weight and drop, and then be discharged from the lower end thereof and dispersed back to the upper part of the filtration layer by the action of the spreading plate 12. become. Sewage (water and contaminants) discharged from the sand lifting pipe 5 crosses the weir plate 16 of the separation chamber 4 and enters the overflow chamber 17, and the discharge pipe 15
Will be discharged outside the tank. This discharge pipe 15
Since the water level a of the filtered water is set considerably lower than the water level a, the water level b of the separation chamber 4 is kept lower than the water level a of the filtered water. Due to this difference in water level, the filtered water in the tank 1 flows out from the lower end of the wash sand drop pipe 8, flows upward in the opposite direction of the fall of the filtered sand, and flows into the separation chamber 4, where it flows into the filtered sand. Will be backwashed. In addition, air is blown into the sand washing drop pipe 8 through the fumaroles 10 and 10 in the lower part thereof, and the bubbles rise in the pipe 8. As a result, the washing action due to gas-solid collision is exerted, and the washing effect of the filter sand is remarkably improved together with the above-mentioned backwashing action.

Therefore, the air coming out from the upper end of the sand raising pipe 5 enters the pressure tank 13, but the lower portion of the pressure tank 13 is submerged in water, so the pressure P in the tank becomes high and the water level c in the tank rises. By pushing down to the lower end of 13, a water level b and a water level difference H in the separation chamber 4 will occur. In this case, since the pressure tank 13 and the weir pressure chamber 18 are communicated with each other by the ventilation pipe 19 and the lower portion of the weir pressure chamber 18 is also submerged in water, the pressure inside the weir pressure chamber 18 is also within the pressure tank 13. It becomes the same pressure as the pressure P. As a result, the water level d of the weir plate 16 on the separation chamber side becomes the same as the water level c of the pressure tank 13, and the overflow chamber side of the weir plate 16 communicates with the discharge pipe 15, so that the water level e is The water level f is lower than the water level d by a water level difference H. Therefore, the sewage that has flowed into the separation chamber 4 enters the chamber from one lower end of the weir pressure chamber 18, passes over the weir plate 16, enters the overflow chamber 17, and is taken out of the tank through the discharge pipe 15. Then, when the amount of air from the sand lifting pipe 5 increases, the increased air escapes from the lower end of the pressure tank 13, so that the water level c in the pressure tank 13 increases.
Is always maintained constant regardless of the amount of air discharged from the sand lifting pipe 5. Therefore, the water level d in the weir pressure chamber that overflows the weir plate 16 is always maintained constant, and the amount of overflow water of the weir plate 16, that is, the amount of water discharged from the discharge pipe 15 is almost independent of the amount of air discharged from the sand lifting pipe 5. A certain amount can be maintained.

Further, if the pressure tank 13 is moved up and down by the elevating mechanism 14, the water level c will fluctuate up and down accordingly, and the water level d in the weir pressure chamber 18 will fluctuate accordingly. The amount of flowing water, that is, the amount of water discharged from the discharge pipe 15 can be changed.

From the above, when the quality of the filtered water deteriorates, it is possible to increase the amount of air blown into the lifting sand pipe to increase the amount of lifted sand and change the sand cleaning effect.

(Effect of the device) Since the sand filter device of the present invention has the above-mentioned configuration, the filter sand returning from the lifted sand pipe to the filter layer is backwashed with filtered water in the wash sand drop pipe. In addition to the action, the gas-solid collision action by the bubbles of the air supply enables the washing and the removal of adhered contaminants sufficiently, and the washing effect is greatly improved. Further, in the device of the present invention, the discharge amount is kept substantially constant by the pressure chamber surrounding the pressure tank and the weir plate and their communication, regardless of the amount of air from the sand lifting pipe. Correspondingly, the amount of lifted sand can be increased and the required cleaning effect can be obtained. Further, by adjusting the vertical position of the pressure tank, it is possible to adjust the drainage amount, and it is possible to provide a device that is resistant to load fluctuations and has an excellent cleaning effect.

[Brief description of drawings]

 The drawing is a longitudinal sectional view showing an embodiment of the device of the present invention. DESCRIPTION OF SYMBOLS 1 ... Filtration tank, 4 ... Separation chamber, 5 ... Sand-lifting pipe 6 ... Air supply pipe, 8 ... Sand washing falling pipe 10 ... Fume hole, 12 ... Air supply pipe 13 ... Pressure tank, 14 ... Elevating mechanism 15 ... Exhaust pipe, 16 … Weir plate 17… Overflow chamber, 18… Pressure chamber 19… Ventilation pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B01D 29/62

Claims (1)

[Scope of utility model registration request] 1. A separation chamber for filtering sand and drainage, in which the upper part of the sand lifting pipe is projected, is provided in the upper part of a filtration tank in which the sand lifting pipe by an air lift is erected in the center, and the bottom part of the separation chamber is provided. , A long sand wash drop pipe with a blasting pipe connected to the lower part and an air feeding pipe connected to the lower part is installed, and a pressure tank with the lower end surrounded by the upper end of the sand raising pipe is opened and lowered in the separation chamber. A weir plate is provided between the pressure tank and the discharge pipe provided on the upper portion of the filtration tank while being adjustable, and a pressure chamber having an open lower end is formed across the weir plate. A continuous sand filter, characterized in that the upper part of the pressure tank communicates with the upper part.