JP2000093941A - Floating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain high quality treated water by executing effective floating separation by preventing a turbulent flow in a tank. SOLUTION: A raw water feed pipe 2 is raised to midway in a tank 1. A pressure water feeder is connected to the raw water feed pipe 2 via a valve 3. A water collecting pipe 4 is provided in a lower part of the tank 1. A connecting part 10 of a distributor 5 fits outside an upper end part of the raw water feed pipe 2. An aperture 6 for flowing out of water is provided to the distributor 5 so as to face an after flow in a gyratory direction. A skimmer 7 for scratching off a floated scum is provided near a water surface of the tank 1. A depth of water D of the aperture 6 of the distributor 5 is set at 3 to 18 cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized flotation apparatus for flotation-separating a suspended substance from water containing the suspended substance, and in particular, supplies the water to be treated into a tank body by a swirling distributor. And a pressure flotation device.

[0002]

2. Description of the Related Art A distributor is provided in a tank so as to be swivelable, and while the distributor is swirled, mixed water of raw water and pressurized water flows out of the distributor into the tank to float suspended substances in the tank. As a pressure flotation device designed to be separated,
There is one described in JP 23668.

[0003] The distributor disclosed in the publication has a tubular wastewater distribution arm extending in the radial direction of the tank body, and a water outlet pipe projecting below the wastewater distribution arm. A plurality of the arms are provided at intervals in the longitudinal direction of the arm.) And an opening for water outflow provided on a side surface of the water outlet pipe.

[0004] A plurality of the openings are provided on the side surface of the water outlet pipe extending in the up-down direction at an interval vertically. The opening is open toward the front side in the turning direction of the distribution arm (FIG. 4 of the same publication).

[0005] When the water outlet opening is provided so as to open toward the upstream side in the swirling direction of the distributor as in the conventional case described above, the outflow from the opening is easily disturbed, and the suspended matter becomes finer or bubbles are generated. Is separated from the suspended substance, thereby lowering the separation efficiency.

In order to solve such problems and provide a pressurized flotation device excellent in separation efficiency, the present applicant firstly provided a tank having an annular peripheral wall and a central portion of the tank. A distributor extending in a radial direction from the central portion and capable of turning around the central portion in the tank, a turning drive device for the distributor, and a means for supplying a mixed water of raw water and pressurized water into the distributor. A pressurized flotation device comprising a mixed water outlet provided in the distributor and opening toward the downstream side in the rotational direction has been proposed (Japanese Patent Application No. Hei 9 (1999)).
-80309. Hereinafter, it is referred to as “first application”. ).

In the pressure flotation device of the prior application, since the water flows out from the distributor toward the downstream side in the distributor turning direction, the flow of the water is not easily disturbed. For this reason, the suspended substance is prevented from being finely divided and bubbles are prevented from being detached, so that an efficient flotation separation process is performed.

In the pressure flotation apparatus of the prior application, the upper end of the distributor is positioned at least 10 cm below the water surface, for example, 20 to 50 cm below the water surface, in order to efficiently perform solid-liquid separation. Is preferred.

[0009]

In the above-mentioned pressure flotation apparatus of the prior application, the mixed water of the raw water and the pressurized water is discharged from the mixed water outlet of the distributor immersed in water to form a solid-liquid mixture of the suspended substance and the treated water. Although separation is performed, in order to improve the quality of treated water in the pressure flotation device of this earlier application,
It is desired that the flow of the mixed water of the raw water and the pressurized water discharged from the mixed water outlet of the distributor and the flow of the water in the tank are not disturbed by interference with each other. That is, when the flow of the water is disturbed, micro air bubbles (micro air) generated from the pressurized water are associated with each other and become difficult to be adsorbed on the suspended substance, or the micro air once adsorbed on the suspended substance is re-produced by the disturbance of the water. The separation causes troubles such as deterioration of the floating property of the suspended substance, and prevents efficient floating separation.

According to the present invention, the flow of mixed water discharged from the mixed water outlet of the distributor and the flow of water in the tank in the pressure flotation device of the prior application are reliably prevented, and the suspended substance By effectively performing flotation separation,
An object of the present invention is to provide a pressurized flotation device capable of stably obtaining treated water having good water quality.

[0011]

SUMMARY OF THE INVENTION A pressure flotation device according to the present invention has a tank having an annular peripheral wall, and extends radially from a center portion of the tank body. A distributor capable of turning in the tank body, a turning drive device for the distributor, a unit for supplying a mixed water of raw water and pressurized water into the distributor, and a rotating direction downstream side provided in the distributor. A pressurized levitation device comprising a mixed water outlet opening, wherein the mixed water outlet provided in the distributor is located at a depth of 3 to 18 cm in the tank body. I do.

In other words, the present inventors have made it possible to reliably prevent the flow of the mixed water discharged from the mixed water outlet of the distributor and the flow of the water in the tank in the pressure flotation device of the prior application, As a result of intensive studies to efficiently perform the flotation separation of suspended matter, it was found that the discharge position of the mixed water of raw water and pressurized water into the tank greatly affected the turbulence of the water flow.

If the depth of the mixed water outlet of the distributor is shallow and too close to the water surface, the suspended substance (scum) which floats due to the rotation of the distributor body or the blowing of the mixed water is easily disturbed, and the scum emits bubbles. And the quality of the treated water deteriorates. Conversely, if the depth of the mixed water outlet of the distributor is too deep, the upward flow of the mixed water will be in a turbulent state, and micro air will be separated during the scum floating process, so that the quality of the treated water will also deteriorate.

By disposing the mixed water outlet of the distributor at a depth of 3 to 18 cm in the tank according to the present invention, disturbance of the mixed water and water in the tank is prevented, and scum floating and solid-liquid separation are performed. Can be performed efficiently, and as a result, it is possible to improve and stabilize the quality of treated water.

In the present invention, the water depth in the tank at the outlet of the mixed water outlet of the distributor is a distance from the water surface to the upper end (top) of the opening of the outlet of the mixed water outlet, as shown in FIG.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1A is a longitudinal sectional view of a pressure flotation device according to an embodiment, and FIG. 1B is a plan view of the same. FIG. 2 is an enlarged view of the distributor.

The tank body 1 having a ring-shaped peripheral wall is formed in a conical shape whose bottom is lower toward the center, and the pit 1 is formed in the center.
a is provided. Raw water supply pipe 2 from this pit 1a
Is started up halfway in the tank body 1. A pressurized water supply device (not shown) is connected to the raw water supply pipe via a valve 3.

A water collecting pipe 4 is provided below the tank body 1. The water collecting pipe 4 is a tubular member that circulates along the peripheral wall of the tank body 1, and is provided with a hole-shaped water collecting port at predetermined intervals in the longitudinal direction. In addition, this water collecting port may be provided on any of the upper surface, the side surface, and the lower surface of the water collecting pipe 4, but is preferably provided on the lower surface side so that the inflow raw water is difficult to flow in a short circuit. Reference numeral 4a denotes a water collection drain pipe connected to the water collection pipe 4.

A connecting part (center cage) 10 of the distributor 5 is fitted on the upper end of the raw water supply pipe 2. The four distributors 5 extend in the radial direction of the tank 1, and the distributors 5 are assembled (connected) at the center of the tank 1. The connecting portion 1 having a cylindrical shape is formed downward from the collecting portion of the distributor 5.
0 is protruding.

The distributor 5 is turned inside the tank 1 by a motor 8. An opening 6 for water outflow is provided in the distributor 5 so as to face the wake in the turning direction.

A skimmer 7 for scraping floating scum is provided near the water surface of the tank body 1. The gap 7 is also rotated (turned) integrally with the distributor 5 by the motor 8. Alternatively, a reverse gear may be provided on the motor 8 so that the distributor 5 and the skimmer 7 can be rotated in opposite directions by a double shaft. A scum outflow portion 9 a and a trough 9 are provided on a part of the peripheral wall of the tank body 1. A sludge valve 11 is connected to the pit 1a.

In the pressurized flotation apparatus of the present embodiment, a gap of about 2 to 5 mm is provided between the outer periphery of the upper end of the raw water supply pipe 2 and the inner periphery of the connecting portion 10, and the raw water supply pipe is provided. Reference numeral 2 is inserted into the communication section 10 by about 10 to 30 cm.

As shown in FIG. 2, the distance D between the water surface W of the tank 1 and the upper end (top) 6a of the water outflow opening 6 of the distributor 5 is 3 to 18 cm.

If the distance D is less than 3 cm, the floating scum is disturbed by the rotation of the distributor 5 and the outflow of water from the opening 6, releasing bubbles and sedimentation, and the quality of the treated water tends to deteriorate. Conversely, when the distance D exceeds 18 cm, the upward flow of water flowing out of the opening 6 becomes a turbulent state,
Micro air separation from scum occurs during the ascent process,
After all, the quality of the treated water tends to deteriorate.

The setting of the water depth can be performed, for example, as follows. When designing the pressurized flotation device, design is made so that the set water level in the tank and the distributor have a predetermined positional relationship. The configuration is such that the height of the distributor can be freely changed. For example, a distributor is provided movably in the height direction on a rotating shaft, and the position of the distributor is adjusted according to the water level in the tank. For example, in the case of the pressurized flotation device of FIG. 1, the fitting depth between the communication part (center cage) 10 of the distributor 5 and the upper end of the raw water supply pipe 2 is configured to be variable. The water level in the tank can be changed freely. For example, the water depth of the distributor is adjusted by setting up the treated water outlet pipe and making the position of the upper end thereof variable so that the water level can be adjusted.

Among the above methods, the above method is a preferable method because it can easily cope with a change in the amount of treated water.

Although the present invention is not particularly limited, when the tank body 1 has a processing capacity of 15 to 25 m ³ / Hr,
The diameter of the opening 6 is about 5 to 7 cm.
A total of about 20 to 28 pieces are provided in the book distributor 5, and the outflow velocity of water from the opening 6 is 5 to 15 cm / sec.
It is preferable to set it to about c.

In order to prevent turbulent flow of water in the tank body 1 with the distributor 5 and the skimmer 7, the rotation speed (peripheral speed) of the distributor 5 and the skimmer 7 is about 1 to 3 m / min. Is preferred.

In the present invention, as shown in FIG. 4, a rectifying plate 12 may be provided on the downstream side from the upper portion of the distributor 5 (ie, so as to protrude above the opening 6). The width of the current plate 12 is preferably about 120 to 180 mm. Further, it is preferable that the current plate 12 be provided with a gradient of about 1/20 to 1/30 so that the current plate 12 is lowered as the distance from the distributor increases.

In the present invention, it is preferable to provide a bubble vent hole having a diameter of about 3 to 8 mm at the end of the distributor 5 in order to extract air accumulated in the distributor 5.

[0032]

The present invention will be described more specifically below with reference to examples and comparative examples.

Examples 1 to 6 and Comparative Examples 1 to 3 The levitation separation was performed by the pressure levitation apparatus shown in FIG. After adding an inorganic coagulant to raw water (industrial water) to generate flocs, mixed water obtained by mixing pressurized water with about 20% of raw water is
The liquid was released from the opening 6 through the distributor 5 through the connecting part 10 to perform solid-liquid separation of the suspended substance (scum) and the treated water (the target value of the treated water quality was SS 4 mg / L). At this time, the distributor 5 is moved up and down to change the water depth (distance D) of the opening 6, the treated water is sampled and the SS is measured, the relationship between the water depth of the opening 6 and the treated water SS is examined, and the results are displayed. 1 and FIG.

The apparatus specifications and processing conditions other than the water depth at the opening of the distributor were as follows.

Processing capacity of tank body 1: 20 m ³ / Hr (including pressurized water volume) Diameter of opening 6: 6 cm Number of opening 6 (total): 24 Outflow velocity of water from opening 6: 8 cm / sec Distributor 5 And the rotation speed (peripheral speed) of the gap 7: 2.5 m / min. The distance between the distributor 5 and the water collecting pipe 4: 120 cm. The height (depth) of the tank body 1: 150 cm.

[0036]

[Table 1]

From Table 1 and FIG. 3, it is understood that when the water depth of the opening of the distributor is 3 to 18 cm, treated water having good water quality can be obtained.

[0038]

As described above in detail, the pressurized flotation apparatus of the present invention can prevent turbulence in the tank, perform efficient flotation separation, and stably obtain high-quality treated water. This pressure flotation device has a relatively simple configuration and requires only a small height of the tank body.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a plan view of a pressure flotation device according to an embodiment.

FIG. 2 is an enlarged view of a distributor.

FIG. 3 is a graph showing the results of Examples 1 to 6 and Comparative Examples 1 to 3.

FIG. 4A is a perspective view of a distributor of a pressure flotation device according to another embodiment, and FIG. 4B is a cross-sectional view of the distributor of FIG.

[Explanation of symbols]

 Reference Signs List 1 tank body 2 raw water supply pipe 3 pressurized water valve 4 water collecting pipe 5 distributor 6 opening 7 skimmer 8 motor 9 trough

Claims (1)

[Claims] 1. A tank having an annular peripheral wall, a distributor extending in a radial direction from a central portion of the tank, and capable of rotating around the central portion in the tank, and a distributor. Pressurized floating device comprising: a turning drive device for supplying a mixed water of raw water and pressurized water into the distributor; and a mixed water outlet provided in the distributor and opening toward the downstream side in the rotational direction. A pressurized flotation device, wherein the mixed water outlet provided in the distributor is located at a water depth of 3 to 18 cm in the tank body.