JPH09239395A - Deep layer water treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stirring efficiency and to facilitate maintenance. SOLUTION: This device includes an inside cylindrical pipe 2 for downward water flow which is disposed perpendicular in the central part of a treating vessel 1 of a vertical type and arrives near at the tank bottom, an outside cylindrical pipe 3 for downward aeration water flow disposed concentrically from the top end of the inside cylindrical pipe 2 down to a required position and an impeller 5 which is disposed to face the respective top end inlets of the air supplying pipe 4 for aerobic operation disposed at the top end of the outside cylindrical pipe 3, the inside cylindrical pipe 2 and the outside cylindrical pipe 3 and forms the downward wafer flow in the inside cylindrical pipe 2 and the outside cylinder pipe 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage and other sewage treatment apparatus, and more particularly to a deep water treatment apparatus which can be suitably used for both deep aerobic treatment and anaerobic treatment at a water depth of 10 m or more.

[0002]

2. Description of the Related Art Sewage treatment by deep aeration has been studied for more than 20 years, and many actual plants are already in operation in large cities. Further, in the future, the adoption of deep aeration treatment is being considered as a solution to the difficulty of the site even in middle cities. In particular, the anaerobic treatment / aerobic treatment method aiming at nitrogen removal requires twice as much site area as the conventional standard method, so there is an increasing demand for wastewater treatment by deep aeration.

A problem with deep aeration processes is the adverse effect of excess nitrogen that dissolves at large depths. That is, this extra nitrogen becomes fine bubbles in the final settling tank of the wastewater treatment step and adheres to the surface of the sludge to raise the sludge, which makes sludge separation by natural sedimentation difficult.

For this reason, the depth of aeration water is generally set to 4 to 5 m today, and deep aeration treatment of 10 m or more has not been performed.

The system currently in operation for deep aerobic treatment is mainly the diffuser plate system.

However, since the diffuser plate method cannot be adopted in the anaerobic treatment, an upflow type underwater aerator is currently used. This upflow submersible aerator can be used for both anaerobic operation and aerobic operation, but the flow pattern of agitation in the tank is divided into upper and lower layers, and it cannot be said that agitation is sufficient.

Further, in the case of an underwater aerator, a mechanical seal is used to protect the electric motor and bearings, but an overhaul of the entire device is required once every two to three years for this inspection and maintenance.

[0008]

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to provide a deep water treatment system which has good stirring efficiency and is easy to maintain.

[0009]

A deep water treatment apparatus according to the present invention comprises an inner cylindrical pipe (2) for vertically descending water, which is vertically provided at the center of a vertical treatment tank (1) and reaches near the bottom of the tank. And the inner tube
An outer cylinder pipe (3) for converging from the upper end of (2) to the required position for descending aeration water flow, and an air supply pipe for aerobic operation provided at the upper end of the outer cylinder pipe (3). (4), the impeller (2) provided so as to face the upper end inlets of the inner tubular pipe (2) and the outer tubular pipe (3), and forming a descending water flow in the inner tubular pipe (2) and the outer tubular pipe (3). 5) and are provided.

The impeller (5) is driven by a motor (12) provided on the upper surface of the top wall of the processing tank (1). Since the motor (12) is located on the ground, its maintenance is easy and requires almost no need.

The length of the inner tube (2) is such that the water depth at the lower end is about 1
It is determined to be 0 m or more, and is usually about 7 to 9 m. Further, the upper end of the outer tubular pipe (3) substantially coincides with the upper end of the inner tubular pipe (2). The length of the outer tube (3) is
The water depth at the lower end is determined to be about 4 to 5 m or more, and is usually about 3 to 4 m. However, the lengths of the inner tubular pipe (2) and the outer tubular pipe (3) are not limited to the above. As described above, since the outer tubular pipe (3) is concentrically provided from the upper end of the inner tubular pipe (2) to the required position, the power consumption is smaller than that in the case of the single tube system.

The diameter of the inner tube (2) is (Di), and the outer tube is
When the diameter of (3) is (Do), the diameter of the inner tube (2) is
It is preferable to set such that the relationship of ≦ 0.7 Do is established. The diameter of the inner tube (2) is 100m at the bottom stirring velocity.
It is preferable to set so as to secure m / s.

The air may be jetted and supplied to the upper end of the outer tube (3) directly from the outlet end of the air supply pipe (4), or a spar attached to the outlet end of the pipe (4). It may be injected and supplied to the upper end portion of the outer tube (3) through the jilling. The air supply pipe (4) supplies air in the case of aerobic treatment, but is closed in the case of anaerobic treatment.

Preferably, the lower end of the inner cylindrical tube (2) is expanded in a flower shape, and a conical ridge-shaped ridge (9) is arranged in the tube expansion section, and a narrow space is drawn between the tube expansion section and the ridge head. (10) is formed.

The inner tube (2) and the outer tube (3) are treated in the treatment tank (1).
It may be supported by a hanging method or may be fixed to the bottom of the tank.

In a preferred embodiment of the present invention, a return plate for changing the descending aeration water flow coming out of the outer tube (3) upward.
(6) is provided on the outer surface of the inner tube (2) below the lower end outlet of the outer tube (3). By installing the return plate (6), the water flow containing bubbles, which has come out from the lower end of the outer tube (3), is converted into an upward water flow at a predetermined depth. Then, water containing only the amount of air absorbed at the water depth near the outlet is carried to the bottom of the tank by the inner tube (2). As a result, only the amount of air required for the aerobic reaction is supplied to the deep layer, and the excess air supply is suppressed. Therefore, as described above, there is no problem of sludge floating due to excess air supply.

On the other hand, in the anaerobic treatment, the return plate (6) serves to improve the stirring efficiency.

In another preferred embodiment of the invention, the lower surface of the impeller (5) has a partition ring (7) of the required diameter.
Are concentrically provided, and the lower end thereof is fitted into the upper end of the inner tubular pipe (2) with a small gap. An auxiliary impeller (8) may be provided on the inner surface and / or the outer surface of the partition ring (7). The stirring efficiency is improved by installing the auxiliary impeller (8). The partition ring (7) is concentrically provided on the lower surface of the impeller (5), for example, at a position near 0.7 Do. On the outside of the partition ring (7), the impeller (5) and optionally an auxiliary impeller (8) cause the outer tube (3) to form a descending water flow, and on the inside of the partition ring (7) the impeller (5).
And the auxiliary impeller, which is provided if necessary, is the inner tube
Form a descending water flow at (2). The number of impeller pieces may be different inside and outside the partition ring (7). That is, the number of inner impeller pieces may be larger or smaller than the number of outer impeller pieces.

The impeller (5) and the auxiliary impeller (8) optionally provided may be provided in a plurality of upper and lower stages on the coaxial line to adjust the amount of water and the water pressure.

As the impeller (5) and the auxiliary impeller (8) optionally provided, those having a pitch gradually increasing from the position corresponding to the upper end of the inner cylindrical tube (2) toward the center can be used. By using such an impeller, the amount of water required for stirring at the bottom of the tank can be supplied through the inner cylindrical pipe (2) without any trouble. It is also possible to use an impeller having a constant angle of attack, a constant pitch, or a gradually increasing angle of attack that is continuous from the base end to the tip.

The deep water treatment apparatus according to the present invention can be applied to both continuous operation and batch operation.

Further, the deep water treatment apparatus according to the present invention can be applied to both aerobic treatment and anaerobic treatment of water.

First, in aerobic operation, sewage near the water surface to be treated is sucked into the suction port (11) provided at the upper end of the outer tube (3).
Sucked into the outer tube (3) and the inner tube under the impeller (5).
It is divided into (2) and is forcibly lowered by the impeller (5) and the auxiliary impeller (8) which is optionally provided. Air is supplied from the air supply pipe (4) to the upper end of the outer cylinder pipe (3), and a water flow containing bubbles is formed in the outer cylinder pipe (3). The water flow containing the bubbles is sent out by the impeller (5) and the auxiliary impeller (8), which is provided in some cases, from the lower end outlet of the outer tube (3) to a zone with a water depth of about 4 to 5 m, and is lowered by the return plate (6). The water flow can be changed upward. Therefore, the water flow containing bubbles does not reach a zone deeper than this, so that excess air does not dissolve in the water.

Air aerated at a water depth of about 4-5 m dissolves in water in proportion to the gas partial pressure at that depth. The air blown more than necessary at this water depth becomes bubbles as shown in FIG. 1 and floats up and is released into the atmosphere.

On the other hand, water containing only the amount of air absorbed (dissolved) at a water depth of 4 to 5 m is carried to the bottom of the tank by the inner cylindrical pipe (2). As a result, only the amount of air required for the aerobic reaction is supplied to the deep layer, and the excess air supply is suppressed. The wastewater led to the bottom of the tank consumes oxygen in the dissolved air and undergoes an oxidation reaction, and then joins the wastewater aerated above the middle part of the treatment tank (1) to absorb the air. .

Thus, the sewage to be treated is aerated at a predetermined water depth by the downward water flow, and at the same time, it is agitated at the bottom of the tank with a water flow having a small amount of dissolved air, and the flow along the tank wall is aerated on the way. It merges with the water flow, rises to the water surface, and is again sucked into the suction port (11).

Next, in the anaerobic operation, the air supply pipe
Anaerobic reaction is promoted under stable stirring conditions by simply stopping the air supply from (4) to the outer tube (3) and otherwise performing the same operation as in aerobic operation. .

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, the deep water treatment apparatus according to the present invention comprises an inner cylindrical pipe (2) vertically provided in a central portion of a vertical treatment tank (1) and an upper end portion of the inner cylindrical pipe (2). To the middle part of the outer cylinder pipe (3), and the air supply pipe (4), the inner cylinder pipe (2) and the outer cylinder pipe (4) provided at the upper end of the outer cylinder pipe (3). 3)
And an impeller (5) provided so as to face each upper entrance.

The impeller (5) is driven by a motor (12) provided on the upper surface of the top wall of the processing tank (1). The impeller (5) forms a descending water flow inside the inner tubular pipe (2) and the outer tubular pipe (3). The impeller (5) and the auxiliary impeller (8) have a constant constant angle of attack from the base end to the tip.

The inner cylindrical pipe (2) reaches near the bottom of the tank, and its length is determined so that the water depth at the lower end is usually about 10 m. Further, the length of the outer tube (3) is determined so that the water depth at the lower end thereof is usually about 4 to 5 m. If the diameter of the inner tube (2) is (Di) and the diameter of the outer tube (3) is (Do),
The relation of Di = 0.7Do almost holds. The diameter of the inner tube (2) is set so as to secure a bottom stirring flow velocity of 100 mm / s.

The lower end of the inner cylindrical tube (2) is expanded in a flower shape, and a substantially frustoconical ridge (9) is arranged in the tube expanding section, and a narrow interval (10) is provided between the tube expanding section and the head of the tube. ) Is formed.

The inner cylinder tube (2) and the outer cylinder tube (3) are rectified by the straightening plate (14).
It is supported by a plurality of supporting frames (15) attached to the top wall of the processing tank (1) in a hanging manner.

A return plate (6) is provided on the outer surface of the inner cylindrical tube (2) slightly below the lower end outlet of the outer cylindrical tube (3). Return plate
By (6), the water flow containing bubbles, which is emitted from the lower end of the outer tube (3), is converted into an upward water flow. Then, water containing only the amount of air absorbed at the water depth near the outlet is carried to the bottom of the tank by the inner tube (2).

2 and 3 show a modified example of the impeller (5). The lower surface of the impeller (5) has a diameter of approximately 0.7D.
The partition ring (7) of o is concentrically provided, and the lower end of the partition ring (7) is fitted into the upper end of the inner tubular pipe (2) with a small gap. The partition ring (7) is integrally fixed to the lower surface of the impeller (5).

FIG. 4 shows a second modification of the impeller (5). In this example, a plurality of auxiliary impellers (8) are provided on the outer surface of the partition ring (7) at equal intervals. The stirring efficiency is improved by installing the auxiliary impeller (8). Outside the divider ring (7) the impeller (5) and the auxiliary impeller
(8) causes the outer tube (3) to form a descending water flow, and the partition ring
Inside the (7), the impeller (5) causes the inner tube (2) to form a descending water flow.

FIG. 5 shows a third modification of the impeller (5). In this example, a lower-stage impeller (12) with a smaller diameter than this is provided on the coaxial line of the impeller (5), and the inner tube (2)
Is located in the upper end of the. By installing the lower impeller (12), it is possible to supply the amount of water required for stirring at the bottom of the tank through the inner cylindrical pipe (2) without any trouble.

FIG. 6 shows a modification of the lower end portion of the inner tubular pipe (2). In this example, the lower end of the inner tubular pipe (2) is small and flared, but does not have a throttle. Other configurations are the same as those shown in FIG.

When the deep water treatment apparatus shown in FIG. 1 is operated aerobically, the sewage near the water surface to be treated is sucked into the suction port (11) provided at the upper end of the outer tube (3) and the impeller ( Five)
Underneath, it is divided into an outer tube (3) and an inner tube (2), and they are forcibly lowered by the impeller (5). Outer tube
Air is supplied from the air supply pipe (4) to the upper end of (3),
A water flow containing bubbles is formed in the outer tube (3). The water flow containing the air bubbles is sent by the impeller (5) from the lower end outlet of the outer tube (3) to a zone with a water depth of 4 to 5 m,
The return plate (6) changes the descending water flow upward.

Air aerated at a water depth of about 4-5 m dissolves in water in proportion to the gas partial pressure at that depth. The air blown more than necessary at this water depth becomes bubbles and rises to the atmosphere.

On the other hand, water containing only the amount of air dissolved at a water depth of 4 to 5 m is carried to the bottom of the tank by the inner tube (2). As a result, only the amount of air required for the aerobic reaction is supplied to the deep layer, and the excess air supply is suppressed. The wastewater led to the bottom of the tank consumes oxygen in the dissolved air and undergoes an oxidation reaction, and then joins the wastewater aerated above the middle part of the treatment tank (1) to absorb the air. .

Next, in the anaerobic operation, the air supply pipe
Anaerobic reaction is promoted under stable stirring conditions by simply stopping the supply of air from (4) to the outer tube (3) and otherwise performing the same operations as in aerobic operation. .

[0043]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it is possible to provide a deep water treatment device which has good stirring efficiency and is easy to maintain.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a deep water treatment device of an embodiment.

FIG. 2 is a vertical sectional view showing a modified example of the impeller.

FIG. 3 is a plan view showing a modified example of the impeller.

FIG. 4 is a plan view showing a modified example of the impeller.

FIG. 5 is a vertical sectional view showing a modified example of the impeller.

FIG. 6 is a vertical cross-sectional view of a deep water treatment device showing a modified example of the inner tube.

[Explanation of symbols]

 1 treatment tank 2 inner cylinder pipe 3 outer cylinder pipe 4 air supply pipe 5 impeller 6 return plate 7 partition ring 8 auxiliary impeller 13 lower impeller

Claims (6)

[Claims] 1. An inner cylindrical pipe (2) for vertically descending water, which is vertically provided in the center of a vertical processing tank (1) and reaches near the bottom of the tank,
An outer cylinder pipe (3) for converging from the upper end of the inner cylinder pipe (2) to the required position for the descending aeration water flow, and an aerobic operation provided at the upper end of the outer cylinder pipe (3). Air supply pipe (4), inner cylinder pipe (2)
And so as to face the upper end inlets of the outer tube (3),
Further, a deep water treatment device comprising an inner cylinder pipe (2) and an outer cylinder pipe (3) and an impeller (5) forming a descending water flow. 2. A return plate (6) for changing the downward aeration water flow coming out of the outer tube (3) to the outer surface of the inner tube (2) below the lower end outlet of the outer tube (3). The deep water treatment device according to claim 1, which is provided. 3. A partition ring (7) having a required diameter is concentrically provided on the lower surface of the impeller (5), and its lower end is fitted in the upper end of the inner tube (2) with a small gap. The deep water treatment device according to 1 or 2. 4. The deep water treatment system according to claim 1, wherein an auxiliary impeller (8) is provided on the inner surface and / or the outer surface of the partition ring (7). 5. The deep water treatment system according to claim 1, wherein the impeller has a pitch that gradually increases from the position corresponding to the upper end of the inner tubular pipe (2) toward the center. 6. The deep water treatment device according to claim 1, wherein a plurality of impellers are provided on the upper and lower sides.