JP3429227B2 - Middle and deep aeration type wastewater treatment equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the use of medium-deep circulation type non
In a wastewater treatment equipment with a terminal long waterway, when aerobically treating wastewater containing organic components, it is possible to perform mid-deep aeration treatment using a vertical axis type surface aeration aerator, a draft tube and a submersible water flow propulsion device. The present invention relates to an intermediate-deep aeration type wastewater treatment device that is made possible.

[0002]

2. Description of the Related Art <Vertical surface aeration aerators> Conventionally, vertical surface aeration aerators have been used for aerobically treating wastewater containing organic components such as municipal wastewater, domestic wastewater, food processing wastewater. It is used.

<Draft tube> Further, a diffusing tube for sending air to the inside or the outside of the lower part of the draft tube is attached, and a submersible ascending or descending flow propulsion device such as a screw type or a submersible pump type is provided above the draft tube. Draft tubes that are included are also used. For example, Japanese Patent Laid-Open No. 10-3052
See Japanese Patent Publication No. 90.

<Deep aeration type waste water treatment equipment> Further, deep aeration type waste water treatment equipment for deep aeration treatment by deepening the water depth of the aeration tank to more than 5 m to about 20 m or more mainly for the effective use of the site. Equipment is also in use. If this deep layer aeration type waste water treatment device is used, the installation area can be reduced.

[0005]

Since the vertical type surface aeration aerator is used by mounting it near the water surface, it is easy to install and easy to maintain, and is suitable for a rectangular or circular aeration tank. Not only is it used, but it is also suitably used for a so-called oxidation ditch that uses an aeration tank of a circulation type endless long channel.

However, the vertical axis type aeration aerator agitates the surface of the wastewater, winds the wastewater into the atmosphere, and brings it into contact with oxygen in the air, so that dissolved oxygen required by microorganisms for purifying the wastewater is obtained. Since it depends on the method of supplying it into the wastewater, when the water depth becomes deep, the flow rate of the wastewater at the bottom of the aeration tank decreases and activated sludge and sludge form a precipitate, and the inside of the tank of these useful mixed liquids. As a result of the obstruction of circulation, the quality of treated water deteriorates. For this reason, the applicable water depth of the vertical surface aeration aerator is limited to within 3 m, and this aerator alone cannot be installed in a deep aeration tank to maintain a high level of treated water quality.

On the other hand, the draft tube has a discharge pressure and a discharge air volume of an air compressor for a diffuser tube for generating an upward flow or a downward flow inside the draft tube, and / or a discharge head of a submersible up or down flow propulsion device. It is also used for deep aeration tanks, because the discharge amount of water and the amount of discharged water can be appropriately selected according to the water depth of the aeration tank to which it is applied.

However, in this draft tube system, both the air diffuser and / or the submersible ascending or descending flow propulsion device have to be deeply buried in the drainage, so that the installation work is complicated and the maintenance is difficult. There was a drawback.

[0009] The present inventors have found that, had conducted extensive studies on the interaction between the vertical axis type surface aeration aerator and draft tube of for some time, Then solve its interaction
Both are wastewater treatment applied to the circulation type endless long canal in the middle and deep layers
We have come to discover the technology.

Under the circumstances, the present invention uses a vertical type surface aeration aerator and secures the advantage that the installation is simple and the maintenance is easy.
In combination with a soft tube, and even a submersible water flow propulsion device
Provided the location, in a water depth is up to about 10m beyond the 3m
Treatment by building a deep circulation type endless long channel
It is an object of the present invention to provide a medium / deep aeration type wastewater treatment device which is capable of improving the water quality and is highly practical .

[0011]

Means for Solving the Problems The middle-deep aeration type wastewater treatment equipment of the present invention has a depth of more than 3 m and up to 10 m.
Circulation type endless long water channel (1) and its circulation type endless long water
A vertical axis type surface aeration aerator (2) provided at the upper part of the corner of the passage (1) and a draft tube (3) provided directly below the aerator (2), 3), the center line, that is provided to the center of rotation substantially coincident impeller (2a) of the aerator (2), the inner diameter d _DC and the aerator of the draft tube (3) (2 ), The outer diameter d _IP of the impeller (2a) is 1.0 · d _IP <d _DC ≦ 1.2 · d _IP , and the bottom of the circulation type endless long channel (1) is
Vertical distance to the bottom of the draft tube (3)
That the bottom clearance c _bt, the draft tube
Maintaining a passage area equivalent to 1.5 to 2.5 times the cross-sectional area of (3)
Be set to a certain distance, and the circulation-type endless
A submersible water flow propulsion unit (4) is installed in the long channel (1).
It is characterized by that.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The intermediate-deep aeration type wastewater treatment equipment of the present invention is a medium-deep circulation type endless device having a water depth of more than 3 m and up to 10 m.
Corner of long canal (1) and its circulation-type endless long canal (1)
Vertical axis type aeration aerator (2) provided on the upper part of the part,
Draft tube installed just below the aerator (2)
(3) and a submersible water flow propulsion device (4) .

[0014] depth of the circulation type non-end length waterway medium deep (1) are limited to a 10m exceed 3m. When the water depth is within 3 m, the purpose can be achieved by a device using a conventional aerator or a draft tube, so that it is not necessary to use the device of the present invention. The water depth is 10m
If it exceeds, a rising flow will be generated in the draft tube (3).
You will need to add extra power to
As a result, the power efficiency of the aerator (2) deteriorates.

Corner of a circulation type endless long channel (1) in the middle and deep layers
A vertical axis type surface aeration aerator (2) is provided on the upper portion of the curved portion . As the aerator (2), an aerator that has been used in the depth of water within 3 m can be used. Regarding the required capacity of the aerator (2), the dissolved oxygen dissolution capacity required for the wastewater can be obtained based on the amount of wastewater to be treated and the average BOD load amount calculated from the BOD concentration that is an index of organic matter in the wastewater. The model is selected as appropriate, and is selected by taking into consideration the impeller (2a) (agitating blade) diameter, rotation speed, and drive power.

In the present invention, the above vertical axis type surface aeration aerator (2) is used in combination with the draft tube (3). The draft tube (3) is attached to this aerator.
It is provided directly under (2).

The shape of the draft tube (3) is a vertical cylindrical type, a lower divergent (trumpet tube) type, an upper divergent tube (trumpet tube).
A mold, an upper neck portion drawing mold, and the like can be appropriately selected. It is also possible to install a known current plate or partition plate inside the draft tube (3).

The above-mentioned various draft tubes (3) are used for medium and deep layers.
In order to install it in the circulation-type endless long channel (1) , a method of fixing it to the tank bottom plate with legs, a method of passing a guide strut from the tank bottom plate to the tank upper bridge portion, and the like can be adopted.

It is also important to maintain the bottom clearance c _bt , which is the vertical distance between the bottom of the medium-deep circulation type endless long water channel (1) and the bottom of the draft tube (3), and prevents the inflow of the drained water. 1.5 to the cross-sectional area of the draft tube (3) normally used for
Set a distance that can hold a passage area equivalent to 2.5 times . Here, the passage area equivalent to 1.5 to 2.5 times means (1.5 to 2.5) × π (d _DC / 2) ² = 2π (d _DC / 2) × when the inner diameter of the draft tube (3) is d _DC. from equation of c _bt, since the c _bt / d _DC = 0.375~0.625, bottom clearance c _bt will be referred to from .375 to .625 times the inside diameter d _DC draft tube (3).

The present inventors initially assumed that additional power for generating an upward flow inside the draft tube (3) would have to be added, but it was clarified by experiments. Also, when applying aeration in the middle and deep layers, install the aerator (2) in the draft tube.
It was found that, if used in combination with (3) and special measures were taken, the aerator (2) originally held would be satisfied with the upper and lower layer agitation ability (that is, almost equivalent drive power) over the entire aeration tank.

That is, if the following measures are taken, the aerator can be installed only in the newly installed draft tube (3).
It is possible to concentrate the suction force (that is, the lifting force) of (2).

First, it is necessary to provide the draft tube (3) so that its center line substantially coincides with the rotation center of the impeller (2a) of the aerator (2).
With this configuration, the suction force of the aerator (2) can be uniformly and intensively applied to the drainage in the draft tube (3).

Therefore, the present inventors have conducted an experiment on the suitability of the outer diameter d _IP of the impeller (2a) of the aerator (2) and the inner diameter (inner diameter of the straight body portion) d _DC of the draft tube (3). At d _DC
As shown in the relationship between the / d _IP and the oxygen dissolution efficiency, the inner diameter d _DC of the draft tube (3) must at least exceed the outer diameter (outermost circumference) d _IP of the impeller (2a), and the draft Inner diameter d _DC of tube (3) and outer diameter d of impeller (2a)
The ratio d _DC / d _IP of the _IP was found to be must be within 1.2 times. That is, in the present invention, the relationship between the inner diameter d _DC of the draft tube (3) and the outer diameter d _IP of the impeller (2a) of the aerator (2) is 1.0 · d _IP <d _DC ≦ 1.2 · d _IP . It is necessary to devise that there is in.

As the impeller (2a) of the aerator (2), a reverse cone (reverse cone) type stirring blade, a propeller type stirring blade, a screw type stirring blade or the like can be used, but the draft tube (3) The mid-deep aeration type wastewater treatment equipment of the present invention used in combination with the above, even if it is installed as a single unit (meaning that only one draft tube (3) is required), the vertical stirring force for circulation in the tank can be obtained. The most suitable is the impeller (2a) having a reverse cone shape that is strong and has the best power efficiency for supplying oxygen to the wastewater.

When the shape of the impeller (2a) of the aerator (2) is such an inverted cone type, the top which is the vertical distance between the lowermost end of the center of the inverted cone and the upper end of the draft tube (3). It is particularly preferable to set the clearance c _tp to 0 to 0.3 m. According to experiments, as shown the relation between the top clearance c _tp and shaft power in FIG. 3, the top clearance c _tp is exceeds 0.3 m, the dissolved oxygen is consumed to increase the draft tube (3) in The suction power of the wastewater (which can be judged by the shaft power in Fig. 3) decreases and the oxygen dissolution efficiency deteriorates, while the impeller (2a) is buried in the draft tube (3) 0 m or less (negative distance) In (), since the uppermost end of the draft tube (3) collides with and interferes with a part of the jet flow that should originally be wound up in the atmosphere, the oxygen dissolution efficiency also deteriorates.

The intermediate-deep aeration type wastewater treatment equipment of the present invention is
It is applied to the deep circulation type endless long canal (1). By the way
In addition, the circulation type endless canal is generally called an oxidation ditch .

In the oxidation ditch, the capacity of the aeration tank is almost the same as the discharged water volume for 24 hours (the residence time is about 24 hours), so it is possible to increase the depth of water in the aeration tank. In terms of efficiency, it will bring a great deal of advantages over the rectangular and circular aeration tanks.

However, in the oxidation ditch, since the shape of the aeration tank is a circulation type endless long channel,
The third role of the installed aerator (2) is that it is essential to have a function to generate a circulating flow in the drainage in the long water channel in the longitudinal direction. This aerator (2) is installed at 1 to 4 places in the long water channel. Therefore, in the case of a medium-deep aeration tank, at a point away from the installation point of the aerator (2) in the long channel, the flow velocity of the drainage in the bottom deep layer decreases and sedimentation of activated sludge occurs. Water quality is inevitable.

Further, in the oxidation ditch, the oxygen in the atmosphere can be reduced to 1 to 3 by utilizing the long water channel structure.
Not only due to the agitation effect of the aerators (2) installed at four locations, but it is taken in from the surface of the drainage that is moving in the long canal, but the surface area can be greatly increased by using a middle-deep aeration tank. It is unavoidable that it will decrease. For example , when the water depth is 6 m (width 6 m), the surface area is 50% compared to when the water depth is 3 m (width 6 m).
Becomes

Therefore , in order to solve such a problem, in the present invention, for the purpose of maintaining the flow velocity of the drainage and stirring, the point where the flow velocity of the drainage begins to decrease away from the installation point of the aerator (2). In addition, a submersible water flow propulsion device that requires low power
(4) Take measures to install . One to four submersible water flow propulsion devices (4) can be installed according to the shape and depth of the circulation-type endless long water channel, the water quality of the inflowing drainage, and the target water quality of the treatment. See FIG. 5 below.

Here, as the submersible type water flow propulsion device (4),
Propeller type, screw type, submersible pump type, etc. can be used, but the oxidation ditch can generate uniform eddy currents in the vertical and horizontal directions of the tank, and because it is a relatively low speed rotation system, it is acclimatized in the drainage. The propeller type with a large-diameter swirl blade that does not cause atomization due to cutting of good activated sludge flocs and that can maintain a uniform flow up to drainage at the bottom of the aeration tank is optimal.

The installation position of the submersible type water flow propulsion device (4) is, as shown in FIG. 5 described later, long from the installation center of the aerator (2) (and the draft tube (3)) where the flow velocity of the drainage starts to decrease. It is desirable to install at a position separated by at least three times the width w of the water channel. From the first installation point to the next (including the case of returning to the same aerator (2) in case of single installation)
If the waterway to the position where the aerator (2) is installed is long, it may be necessary to install the second and third submersible water flow propulsion devices (4).

[0033]

EXAMPLES Next, the apparatus of the present invention will be further described with reference to examples.

[0034]Experimental example 1 Figure 1IsExplanation showing an example of middle-deep aeration type wastewater treatment equipment
It is a figure. Illustration of auxiliary equipment such as a precipitation tank is omitted.
It

This wastewater treatment equipment is used in the middle and deep aeration tanks.(1 ')
And its middle and deep aeration tank(1 ')Vertical surface on top of
Install the aeration aerator (2) and directly below the aerator (2).
It consists of a girder-shaped cylindrical draft tube (3).

The mid-deep aeration tank (1 ') is a prism with a vertical and horizontal length of 2.8 m, and a water depth of 4.5 m. A vertical axis type surface aeration aerator (2) is installed at the center of the upper part of the mid-deep aeration tank (1 ') . The aerator (2) is equipped with an inverted cone type (inverse cone type) impeller (2a) having an outer diameter d _IP of 1 m, a power of 3.7 kw, and a rotation speed of 67 rpm.

The draft tube (3) has an inner diameter d _DC of 1.1.
It has a vertical cylindrical type of m, 3.5m in length, and uses legs on the bottom of the mid-depth aeration tank (1 ') so that it matches the center of rotation of the impeller (2a) of the aerator (2). Fixed.

Bottom and middle aeration tank (1 ') and draft tube
(3) The bottom clearance c _bt, which is the vertical distance to the lowermost end, is set to 0.6 m so that the passage area equivalent to 1.5 to 2.5 times the cross-sectional area of the draft tube (3) can be maintained ( c _bt / d _DC = 0.55).

The top clearance c _tp, which is the vertical distance between the lowermost end of the center of the inverted cone of the aerator (2) and the upper end of the draft tube (3), is set to 0.1 m.

The inner diameter d _DC of the draft tube (3) is
1.1m, outer diameter of impeller (2a) of the aerator (2) d _IP
Is 1 m, the ratio d _DC / d _IP is 1.1, which satisfies the relationship of 1.0 · d _IP <d _DC ≦ 1.2 · d _IP .

Domestic wastewater (inflow: 7 m ³ / day, BOD: 150 to 200 ppm ) as raw water in the above-mentioned middle and deep layer aeration tank (1 ')
) For continuous operation, and after 1 month BO of treated water
D was measured. The conditions and results are shown in Table 1.

[0042] As a reference example 1 draft tube (3), used as the inner diameter d _DC is the 1.3 m, length has a vertical cylindrical 3m, set the top clearance c _tp to 0.4 m, draft tube (3) Of the inner diameter d _DC of the aerator (2) to the outer diameter d _IP of the impeller (2a) d _DC / d _IP is set to 1.3, and the bottom clearance c
Experimental Example 1 was repeated _except that _bt was set to 0.8 m.
The conditions and results are also shown in Table 1.

Comparative Example 1 After the experiment of Experimental Example 1 , only the draft tube (3) was removed, the other conditions were the same, and the continuous operation was performed.
The BOD of treated water on the day was measured. The conditions and results are also shown in Table 1.

[0044]

[Table 1]      Experimental Example 1 Reference Example 1 Comparative Example 1   Mid-depth aeration tank(1 ')     Shape Square Square Square   Water depth 4.5m 4.5m 4.5m   Aerator (2)     Impeller (2a) shape Reverse cone type Reverse cone type Reverse cone type   Impeller (2a) outer diameter d _IP 1m 1m 1m   Draft tube(3)     Shape Vertical cylindrical type Vertical cylindrical type −   Inner diameter d _DC 1.1m 1.3m-   Bottom clearance c_bt   0.6m 0.8m-   Top clearance c_tp   0.1m 0.4m-   d _DC / D _IP 1.1 1.3 −   BOD of treated water     1 month later 16 ppm 22 ppm   7th day 27 ppm

From Table 1, the BO of treated water in Experimental Example 1
The operating condition where D was 16ppm was the draft tube.
In Comparative Example 1 in which (3) was removed and operation was started by the aerator (2) alone, it deteriorated to 27 ppm on the 7th day, and the vertical axis was shown in the mid-depth aeration process at a water depth of 4.5 m. It can be seen that the combined use of the draft tube (3) is clearly more advantageous than the use of the surface aeration aerator (2) alone. However, even if the draft tube (3) is installed side by side as in Reference Example 1, the inner diameter d _DC of the draft tube (3)
To the outer diameter d _IP of the impeller (2a) of the aerator (2) d _DC
If / d _IP is not set properly, the effect of the adjoining will be insufficient.

[0046]Experimental example 2 Figure 4IsAnother example of middle-deep aeration type wastewater treatment equipment was shown.
FIG. Illustration of auxiliary equipment such as precipitation tanks is omitted.
There is.

This wastewater treatment equipment is a circulation type endless long channel.
(1) , a vertical type surface aeration aerator (2) provided at the upper part of the circulation type endless long channel (1) , and its aerator (2)
It is composed of a cylindrical draft tube (3) provided immediately below.

The circulation type non-end length waterway (1) has a oxidation ditch type. The channel width w is 4 m, the water depth is 6 m, and the drainage capacity is 1200 m ³ .

A vertical axis type surface aeration aerator is provided at the center of the tank between the inner and outer walls of the corner circumference of the circulation type endless long water channel (1).
One (2) is installed. This aerator (2) is an inverted cone type (inverse cone type) impeller (2a) with an outer diameter d _IP of 1.9 m.
Equipped with a power of 17.5 kW and a rotation speed of 58 rpm.

The inner diameter d _{DC of the} draft tube (3) is 2.2.
It has a vertical cylindrical type with a length of 4.5 m and a length of 4.5 m, and its legs are attached to the bottom plate of the circulation type endless long channel (1) so as to match the center of rotation of the impeller (2a) of the aerator (2). It is fixed by using.

The bottom and the draft tube recycling endless length waterway (1) (3) is a vertical distance to the lowermost bottom clearance c _bt is Yes set to 1.2 m, Draft Chu
The distance is set so as to maintain a passing area equivalent to 1.5 to 2.5 times the cross-sectional area of the bush (3) (c _bt / d _DC = 0.55).

The top clearance c _tp, which is the vertical distance between the lowermost end of the center of the inverted cone of the aerator (2) and the upper end of the draft tube (3), is set to 0.3 m.

The inner diameter d _DC of the draft tube (3) is
2.2m, outer diameter d _IP of impeller (2a) of the aerator (2)
Is 1.9 m, the ratio d _DC / d _IP is 1.16, which satisfies the relationship of 1.0 · d _IP <d _DC ≦ 1.2 · d _IP .

Domestic wastewater as raw water (inflow volume: 1200 m ³
/ day, BOD: 150 to 200 ppm) was flown into the above-mentioned oxidation ditch to continuously operate, and the BOD of the treated water after one month was measured. The conditions and results are shown in Table 2.

[0055]Example 1 FIG. 5 is a middle-deep aeration type wastewater treatment device of the present invention.An example ofIndication
FIG. Note that,Illustration of attached equipment such as settling tank
Omitted.

[0056] downstream from the installation position of the aerator (2) in the above Experimental Example 2 circulating endless length waterway (1) L ₁ = 12m
(3 times the width w (4 m) of the long waterway)
Propeller-type submersible water flow propulsion device at two points L ₂ = 8 m (twice the length of the long waterway width w (4 m)) away from the center of the corner contact on the side opposite to the aerator (2).
Two units were installed, one for each (4). As a propeller type submersible water flow propulsion device (4), "SR
4430 "(propeller diameter 2.5m, 38rpm, 4.6k
w) was used.

After the experiment of Experimental Example 2 , the submersible type water jet propulsion device (4) was installed as described above and the continuous operation was performed, and the BOD of the treated water on the 7th day was measured. The conditions and results are also shown in Table 2.

Comparative Example 2 After the experiment of Example 1 , the draft tube (3) and the two submersible water jet propulsion devices (4) were removed, the other conditions were the same, and the continuous operation was performed. BOD of the treated water was measured. The conditions and results are also shown in Table 2.

[0059]

[Table 2]      Experimental Example 2 Example 1 Comparative Example 2   Mid-depth aeration tank (1)     Shape Long canal Long canal Long canal   Water depth 6m 6m 6m   Aerator (2)     Impeller (2a) shape Reverse cone type Reverse cone type Reverse cone type   Impeller (2a) outer diameter d _IP 1.9m 1.9m 1.9m   Draft tube(3)     Shape Vertical cylindrical type Vertical cylindrical type −   Inner diameter d _DC 2.2m 2.2m-   Submersible Water Propulsion Device (4)     Shape-Propeller type-   Number of installation-2 units-   Bottom clearance c_bt   1.2m 1.2m-   Top clearance c_tp   0.3m 0.3m-   d _DC / D _IP 1.16 1.16 −   BOD of treated water     23 ppm after 1 month     7th day 12 ppm   Furthermore, 7 days after that 42 ppm

From Table 2, in Experimental Example 2 , B of treated water
Although OD is preferred and 23 ppm, by installing further submersible water propulsion device (4), BOD of the treated water is 2
It decreased from 3ppm to 12ppm GaWaka possible to improve the water quality
It In Comparative Example 2 in which the draft tube (3) was removed and the aerator (2) was used alone, the BOD of the treated water was
It can be seen that is deteriorated from 23ppm to 42ppm.

[0061]

EFFECTS OF THE INVENTION In the middle-deep aeration type wastewater treatment equipment of the present invention, the circulation of the middle-deep layer having a water depth of more than 3 m up to 10 m.
A ring-type endless long channel (1) , a vertical-type surface aeration aerator (2) provided at the upper part of its corner , and its aerator.
Draft tube (3) directly below (2) and diving water
Flow draft device (4) and the draft tube
The center line of (3) is the impeller (2) of the aerator (2) above.
It is provided so as to substantially coincide with the center of rotation of a), and the inner diameter d _DC of the draft tube (3) and the aerator
It has a specific relationship with the outer diameter d _IP of the impeller (2a) of (2) , and further, the circulation type endless long channel (1)
Vertical distance from the bottom to the bottom of the draft tube (3) above
Set the bottom clearance c _bt which is the separation to a specific distance
There is.

The aerator (2) has a first function of taking in oxygen in the air as dissolved oxygen in the waste water, and a first function of newly sucking the waste water in the draft tube (3) to the upper part to generate an upward flow. It takes on the function of 2 and places the activated sludge and sludge at the bottom of the middle-deep aeration tank (1) on this ascending flow to overflow from the upper end of the draft tube (3) and circulate in the middle-deep aeration tank (1). As a result, it is possible to effectively prevent the generation of precipitates. In the present invention, since the vertical axis type surface aeration aerator (2) is used, it is possible to generate only an ascending flow without generating a descending flow in the draft tube (3) .

Since the circulation type endless long channel (oxidation ditch) (1) system is adopted, the treated water is combined with the vertical type surface aeration aerator (2) and the draft tube (3) . The water quality (BOD, etc.) can be greatly improved, and further , since the diving type water flow propulsion device (4) is installed at a predetermined position of the long water channel , the water quality of the treated water can be further improved.

As described above, the apparatus of the present invention is not only preferable from the viewpoint of improving the quality of treated water, but also has the advantage that it is a medium-deep aeration type and is easy to install and easy to maintain. large.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an intermediate-deep aeration type wastewater treatment device.

[Fig. 2] Inner diameter d _DC of the draft tube (3) and impeller (2
6 is a graph showing a relationship between a ratio d _DC / d _IP of the outer diameter d _{IP of} a) and oxygen dissolution efficiency.

FIG. 3 is a graph showing the relationship between top clearance c _tp and shaft power.

FIG. 4 is an explanatory diagram showing another example of the intermediate-deep aeration type wastewater treatment device.

FIG. 5 is an explanatory diagram showing an example of a medium-deep aeration type wastewater treatment device of the present invention.

[Explanation of symbols] (1)… Middle-deep circulation type endless long channel, (1 ') … Middle-deep aeration tank, (2)… Surface aeration aerator, (2a)… Impeller, (3)
… Draft tube, (4)… Submersible water flow propulsion device

Continuation of the front page (56) References JP-A-59-105890 (JP, A) JP-A-9-52097 (JP, A) Actually opened 55-147898 (JP, U) Actually opened 53-115656 (JP , U) Actual development Sho 51-79964 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/14-3/22 B01F 3/04

Claims (4)

(57) [Claims] 1. The water depth exceeds 3 mMedium and deep layers up to 10 m
Circulation-type endless long channel (1)And itsCirculating endless long waterway
(1) cornerVertical axis type surface aeration air installed at the top
The aerator (2) and the driver installed directly under the aerator (2).
With a soft tube (3), The center line of the draft tube (3) is
Substantially coincides with the center of rotation of the impeller (2a) of the rotor (2).
Is provided so thatthing, Above draft tube(3)Inner diameter d_DCAnd above aerator
Outer diameter d of impeller (2a) of (2)_IPIs 1.0d_IP<D_DC≤ 1.2 · d_IP Have a relationship ofThe bottom of the circulation type endless long channel (1) and the draft tube
(3) Bottom clear run, which is the vertical distance to the bottom edge
S c _bt The cross-sectional area of the draft tube (3) above 1.5
Set to a distance that can hold a passing area equivalent to ~ 2.5 times.
And There is a submersible water flow propulsion device in the circulation type endless long channel (1).
(4) is provided, A mid-deep aeration type wastewater treatment device. 2. An aerator (2) impeller (2a) has a shape of an inverted cone, and a top clearance which is a vertical distance between a lowermost end of the center of the inverted cone and an upper end of a draft tube (3). The middle-deep aeration type wastewater treatment device according to claim 1, wherein c _tp is set to 0 to 0.3 m. 3. A diving type water flow propulsion device (4) is a circulation type endless type.
Long channel (1) aerator (2) and draft tube
The middle-deep aeration type wastewater treatment equipment according to claim 1, which is provided at a position away from the installation position of (3) by a length corresponding to three times the width w of the long waterway or more. 4. A submersible water propulsion device (4) is deep aeration-type waste water treatment apparatus in according to claim 1, wherein the propeller.