JPH0717365Y2 - 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 inventors of the present invention have improved the continuous sand filtering device in which the filtered sand is circulated by an air lift by making an application such as Japanese Patent Application No. 59-61211 (No. Sho 60-171518). 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 raw water, it has a problem that the cleaning effect does not increase. In addition, there is also a problem in that washing by backwashing and dropping the filter sand cannot be expected as a washing effect because it is caused by a flow due to a difference in water level between the filtered water and the washing drainage.

The present invention has been made in order to solve the above problems, and provides a continuous sand filter which can improve the backwashing effect of the filtered sand flowing out from the sand lifting pipe and further improve the filtering performance. It is what

(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.
Filter tank 1 with sand lifting tube 3 by air lift installed upright in the center
A separation chamber 8 for filtering sand and drainage is provided in the upper part of the so as to surround the upper end of the sand removal pipe 3, connected to the bottom of the separation chamber 8 and provided with a long washing sand drop pipe 11 in the vertical direction. At the bottom of the sand drop tube 11,
An air distribution pipe 15 connected to the air supply pipe 14 is provided on the outer periphery thereof, and fumaroles 13, 13 communicating with the air distribution pipe are separated along the circumference of the sand washing drop pipe 11. .

(Operation) In the sand filter configured as described above, the raw water enters from the inflow pipe 4 and passes through the filtration layer a to become clear filtered water, and is taken out of the tank 1 through the outflow pipe 6. The sand in the filtration layer is the sand lifting pipe 3
The air is lifted up from the lower end of the pipe and the sand is washed by the flow of air and water. The washing water and SS flowing out from the upper end of the sand lifting pipe 3 overflow from the separation chamber 8 and are discharged from the tank through the discharge pipe 9. Further, the filtered sand discharged from the sand lifting pipe 3 falls in the washed sand drop pipe 11, and exits from the lower end thereof to return to the filtration layer a. At that time, the filtered sand was washed with a sand drop pipe 11
The air bubbles blown to the lower part of the air will be purified by the action of removing and separating the sand and adhering SS caused by gas-solid collision.

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 elongated filtration tank, and at the center thereof, a sand lifting pipe 3 having upper and lower ends opened at a required interval between the tank bottom and the top plate 2 of the tank is provided. It is erected. Raw water inflow pipes 4, 4 project into the lower part of the filtration tank 1. Further, a filtered water outflow pipe 6 is provided at an upper part of the filtration tank 1 through an overflow groove 5, and an air supply pipe 7 connected to an air supply source (not shown) outside the tank 1 is provided at a lower part of the sand lifting pipe 3. Are connected.

A separation chamber 8 for filtering sand and washing water is provided in the upper part of the filtration tank 1 so as to surround the upper end of the sand lifting pipe 3, and the open upper end of the separation chamber 8 is higher than the water level a in the tank 1. It is set to a low level, and next to the separation chamber 8, there is provided an overflow chamber 10 for cleaning and drainage to which a discharge pipe 9 is connected.

At the bottom of the separation chamber 8, the upper end of a vertically long sand washing drop pipe 11 arranged surrounding the sand lifting pipe 3 is connected, and the lower end of the sand washing drop pipe 11 is provided at an intermediate portion of the sand lifting pipe 3. It is opened above the umbrella-shaped spreading plate 12. Further, at the lower part of the sand washing drop pipe 11, an air distribution pipe 15 to which an air supply pipe 14 is connected is provided on the outer periphery thereof, and along the circumference of the sand washing drop pipe 11, the air distribution pipe
The fumaroles 13, 13 communicating with 15 are separated.

In the above embodiment, the sand wash drop pipe 11 is provided so as to surround the sand lift pipe 3, but the sand wash drop pipe 11 is used as the sand lift pipe 3.
It can also be provided adjacent to.

In the above apparatus, the filtration sand is contained in the tank 1 at a height up to the position below the spreading plate 12 to form the filtration layer a. Then, the raw water flows into the lower part of the tank 1 through the inflow pipes 4, 4 and rises in the filtration layer a, SS is removed to become clear filtered water, which overflows into the overflow groove 6 in the upper part and the outflow pipe. 6
Is taken out of the tank. The filtered sand of the filtration layer a which has captured the contaminants is air-lifted by the air blown into the sand lifting pipe 3 from the air feeding pipe 7, and the lower end of the sand lifting pipe 3 is introduced and pressure-fed upward in the pipe 3. It flows into the separation chamber 8 from the upper end of the sand lifting pipe 3. At that time, since sand, water, and air rise at different speeds in the sand lifting pipe 3, the SS adhering to the sand is separated and washed. Then, the water and the separated SS overflow from the upper end of the separation chamber 8 into the overflow chamber 10 and are discharged from the tank through the discharge pipe 9.

The filtered sand that has flowed out from the sand lifting pipe 3 enters the washing sand drop pipe 11 from the bottom of the separation chamber 8 due to its own weight and falls, and then comes out from the lower end thereof and is dispersed on the upper part of the filtration layer a by the action of the spreading plate 12. Will be returned. In this case, since the upper end of the separation chamber 8 is lower than the water level of the layer 1, the filtered water in the tank 1 flows in from the lower end of the sand washing drop pipe 11 due to the difference in water level, and is directed upward as opposed to the fall of the filtered sand. To flow into the separation chamber 8, where the filter sand is backwashed. Also, a sand washing drop tube
Air is blown into the inside of the tube 11 through the fumaroles 13 and 13 at the lower part thereof, and the bubbles rise in the tube 11. As a result, the cleaning action by gas-solid collision will be exerted,
Washing the filter sand together with the above-mentioned backwashing action with filtered water, SS
The effect of removing is significantly improved.

(Effect of the Invention) As described above, in the sand filter of the present invention, the vertically long sand wash drop pipe is connected to the separation chamber provided around the upper end of the sand lift pipe, and the sand wash drop pipe is connected. Since the air is sent to the bottom of the sand filter, the filtered sand that returns from the lifted sand pipe and returns to the filtration tank is not only backwashed by the filtered water but also gas-solid colliding by air bubbles in the sand washing pipe. As a result, the cleaning and the removal of the adhering SS can be sufficiently performed, the separated SS can be discharged well, and the filtration performance of the apparatus can be greatly improved. Moreover, since the air is sent to the sand washing drop pipe, fumaroles are provided in the circumference of the sand washing drop pipe, and this is made to communicate with the air distribution pipe provided on the outer periphery of the sand washing drop pipe. Because air is sent to the inside of the sand washing drop pipe, there is no need to project anything that obstructs the fall of the sand such as piping, so that the sand flow can be performed smoothly without obstruction and the fumarole is blocked. There is no fear of doing In addition, even if the quality of the filtered water deteriorates due to changes in the raw water, it is possible to control the amount of filtered water for backwashing by adjusting the amount of blown air and prevent a decrease in washing and separation effects. There are many excellent effects.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the device of the present invention,
The figure is an enlarged vertical sectional view of the main part. 1 ... Filtration tank, 3 ... Sand pipe, 7 ... Air pipe, 8 ... Separation chamber, 11 ... Sand washing drop pipe, 13 ... Vent hole, 14 ... Air pipe, a ... Filtration layer

Claims (1)

[Scope of utility model registration request] 1. A separation chamber for filtering sand and drainage is provided in the upper part of a filtration tank in which a sand lifting pipe by an air lift is erected in the center, and a separation chamber for filtering sand and drainage is provided and connected to the bottom of the separation chamber. Then, a long sand washing drop pipe is provided above and below, and at the lower part of the sand washing drop pipe, an air distribution pipe connected to an air supply pipe is provided on the outer periphery thereof,
A continuous sand filter, characterized in that fumaroles communicating with the air distribution pipe are provided along the circumference of the sand washing drop pipe.