JP7145256B2 - Water treatment system and method for improving water treatment system - Google Patents

Description

The present invention relates to a water treatment system with an aerator for dispersing fine air bubbles in a liquid and a method of arranging the aerator. More particularly, the present invention relates to a water treatment system equipped with an aerator used in an aeration tank for treating wastewater and the like, and a method for improving the water treatment system.

As a method for treating wastewater such as sewage and sewage, there is a method in which an aeration tank is installed in the wastewater treatment equipment, an aeration device is installed in this aeration tank, and the air is dispersed in the wastewater as fine bubbles by this aeration device. . The aerator converts oxygen or the like supplied by the blower into fine bubbles and supplies them into the aeration tank to increase the amount of dissolved oxygen in the water to be treated. As aeration equipment, a full aeration type, a swirling flow type, and the like are known.

The full-surface aeration type is characterized by high aeration efficiency (treatment efficiency) because the entire aeration tank is aerated, but sludge tends to accumulate on the bottom of the aeration tank. On the other hand, in the swirling flow type, the sludge at the bottom of the aeration tank is agitated by the swirling flow, so the problem of sludge accumulation on the bottom of the aeration tank is less than in the full-surface aeration type, but the aeration efficiency is inferior.

For example, Patent Literature 1 describes a water treatment system equipped with a full aeration type and a swirl type aerator for the purpose of improving the aeration efficiency and agitating the sludge at the bottom of the aeration tank.
In Patent Document 1, as a specific example of a water treatment system, a first aeration device and a first control device are provided in the middle stage on one side of an aeration tank provided with a partition wall, and a second aeration device and a first control device are provided at the bottom of the aeration tank. It is described that two aeration devices and a second control device are provided. is stated.
Moreover, Patent Document 1 also describes increasing the aeration efficiency by adding an aerator to an existing water treatment system equipped with an aerator.

JP-A-9-276891

In the water treatment system described in Patent Document 1, a plurality of aeration devices with different installation heights are provided in the aeration tank, and a control device is attached to each aeration device to control the water treatment system. As a whole, the scale is large, and the installation and maintenance costs are high.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to improve the stirring efficiency in an aeration tank with a simple structure in a water treatment apparatus equipped with a full-surface aeration type aerator.

As a result of intensive studies on the above problems, the inventors of the present invention have found that, in a water treatment system equipped with a full-surface aeration type aerator, the aerator is arranged so that part of the downward flow caused by aeration passes through the lower side of the aerator. As a result, without providing a plurality of aerators at different heights, a flow is generated to the lower side of the aerator, and the agitation efficiency in the aeration tank is improved, and the water treatment system of the present invention was completed.
In addition, by applying the method of arranging the aerator so that the downward flow partially passes through the lower side of the aerator to the water treatment system equipped with the existing full-surface aeration type aerator, The present inventors have found that a flow occurs even to the side of the aeration tank, making it possible to increase the agitation efficiency in the aeration tank, and have completed the method for improving the water treatment system of the present invention.
Specifically, the present invention is a water treatment system having the following aerator and a method for improving the water treatment system.

A water treatment system of the present invention for solving the above problems is a water treatment system comprising an aeration device substantially over the entire surface of an aeration tank, wherein the aeration device distributes the aeration gas substantially across the entire width of the aeration tank. It is characterized by combining a full-width aeration unit and a partial aeration unit in which the aeration gas is distributed partially in the width direction of the aeration tank.

According to the water treatment system of the present invention, a downward flow space through which the downward flow passes is formed in the area where the partial aeration unit is installed. This downward flow space allows water flow to be generated below the surface where the aerator is installed without increasing the size of the overall system and without reducing the aeration efficiency of the aerator of the general aeration type. As a result, it becomes possible to agitate the bottom of the aeration tank, which has the effect of preventing the accumulation of sludge on the bottom of the aeration tank.

Furthermore, as one form of the water treatment system of the present invention, the partial aeration unit comprises a plurality of aeration gases unevenly distributed on the center side in the width direction of the aeration tank, and the aeration device comprises the full width aeration unit and It is characterized by arranging the partial aeration units alternately.
According to this feature, since downward flow spaces are provided at regular intervals in the aeration tank, a good agitation state is formed at the bottom of the aeration tank.

Further, a method for improving a water treatment system of the present invention for solving the above problems is a method for improving an existing water treatment system in which an aeration device is provided over substantially the entire surface of the aeration tank, wherein substantially the entire width of the aeration tank in the width direction The aeration gas is removed from the full-width aeration unit in which the aeration gas is placed in the aeration tank, and a partial aeration unit in which the aeration gas is placed in a part of the width direction of the aeration tank is provided.

Further, a method for improving a water treatment system of the present invention for solving the above problems is a method for improving an existing water treatment system in which an aeration device is provided over substantially the entire surface of the aeration tank, wherein substantially the entire width of the aeration tank in the width direction In a full-width aeration unit in which the aeration gas is arranged in the aeration tank, the supply of air to a part of the aeration gas is stopped, and a partial aeration unit in which the aeration gas is arranged in a part of the width direction of the aeration tank is formed. is.

According to these methods for improving the water treatment system of the present invention, the surface on which the aeration device is installed can be improved without providing additional equipment to the existing full surface aeration type aeration device and without lowering the aeration efficiency. It is possible to arrange the aerator so that the water flow also occurs below. As a result, it is possible to agitate the bottom of the aeration tank and prevent the deposition of sludge on the bottom of the aeration tank.

According to the water treatment system of the present invention, the downflow space through which the downflow due to aeration passes is formed on the surface where the aerator is provided, so that the entire system can be aerated without increasing the size of the whole system. Water flow also occurs under the surface where the aerator is installed without reducing efficiency. As a result, it is possible to agitate the bottom of the aeration tank and prevent the deposition of sludge on the bottom of the aeration tank.

In addition, according to the method for improving the water treatment system of the present invention, the surface on which the aeration device is installed can be improved without installing other attached equipment to the existing full surface aeration type aeration device and without lowering the aeration efficiency. It is possible to arrange the aerator so that the water flow also occurs below. As a result, it is possible to agitate the bottom of the aeration tank and prevent the deposition of sludge on the bottom of the aeration tank.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows the structure of the water treatment system of the 1st Embodiment of this invention. (a) It is the whole schematic perspective view of the water treatment system of the 1st Embodiment of this invention. (b) It is a top view of the water treatment system of the 1st Embodiment of this invention. (c) It is a side view of the water treatment system of the 1st Embodiment of this invention. (Arrow view of II in FIG. 1b) It is a schematic explanatory drawing which shows the structure of the water treatment system of the 2nd Embodiment of this invention. (a) It is a top view of the water treatment system of the 2nd Embodiment of this invention. (b) It is a side view of the water treatment system of the 2nd Embodiment of this invention. (II-II arrow view in Fig. 2a) It is a schematic explanatory drawing which shows the structure of the water-treatment system of the 3rd Embodiment of this invention. (a) It is a top view of the water treatment system of the 3rd Embodiment of this invention. (b) It is a side view of the water treatment system of the 3rd Embodiment of this invention. (III-III arrow view in Fig. 3a) It is the figure which showed the result of bottom flow velocity simulation. (a) It is the figure which showed the result in the water treatment system of the 2nd Embodiment of this invention. (b) It is the figure which showed the result in the conventional full surface aeration type water treatment system. It is the graph which compared the bottom average flow velocity in the water treatment system of the 2nd Embodiment of this invention, and the conventional water treatment system provided with the aerator of a full surface aeration type.

INDUSTRIAL APPLICABILITY The water treatment system of the present invention is used in a wastewater treatment apparatus or the like having an aerator for dispersing fine air bubbles in a liquid. Preferably, it is used in a water treatment system equipped with an aerator used in an aeration tank for biologically treating wastewater or the like with activated sludge.

The water treatment system of the present invention is a water treatment system comprising an aeration device substantially over the entire surface of an aeration tank, the aeration device comprising: a full-width aeration unit in which aeration gas is distributed substantially across the width of the aeration tank; It is characterized in that it is combined with a partial aeration unit in which an aeration gas is distributed partially in the width direction of the tank.

Hereinafter, embodiments of the present invention will be described in detail with reference to attached screens. It should be noted that this embodiment does not limit the present invention.

[First embodiment]
FIG. 1 is a schematic explanatory diagram showing the configuration of the water treatment system of the first embodiment of the present invention. (a) It is the whole schematic perspective view of the water treatment system of the 1st Embodiment of this invention. (b) It is a top view of the water treatment system of the 1st Embodiment of this invention. (c) It is a side view of the water treatment system of the 1st Embodiment of this invention. (Arrow view of II in FIG. 1b)
As shown in FIG. 1, in the water treatment system 10 of the present embodiment, an aeration device 1a is installed in an aeration tank 2 of a water treatment facility using activated sludge, for example. It is immersed in W (mixture of water to be treated and activated sludge) and has an aeration unit AU composed of a plurality of aeration gases 3 connected to a blower B, and air is supplied from the blower B to these aeration units AU. As a result, air bubbles are generated in the treated water W from the aeration unit AU for aeration.

The aeration unit AU of the aeration device 1a is a full-width aeration unit in which the aeration gas 3 is arranged side by side in substantially the entire width of the aeration tank 2 in the width direction (the vertical direction in FIG. 1b; hereinafter simply referred to as the "width direction"). 4 and a partial aeration unit 5a in which the aeration gas 3 is partially distributed in the width direction. A plurality of full-width aeration units 4 and partial aeration units 5a are arranged in parallel along the length direction of the aeration tank 2 (horizontal direction in FIG. 1b; hereinafter simply referred to as "longitudinal direction").

(aeration tank)
The aeration tank 2 has an upper haunch Hu and a lower haunch Hs in a substantially rectangular parallelepiped tank, and is provided outside with a blower B for supplying oxygen-containing air to the aerator 1a. Inside the aeration tank 2, an aeration device 1a is provided on substantially the entire bottom of the aeration tank 2. As shown in FIG. The position of the aeration device 1a in the depth direction of the aeration tank 2 is not particularly limited, but it is usually installed near the bottom of the aeration tank 2. Considering the restriction of the discharge pressure of the blower B and the balance with the existing facilities, the aeration device 1a may be installed at a relatively high position.

(aeration unit)
The aeration unit AU includes a plurality of aeration gases 3 arranged in the width direction of the aeration tank 2, and a header which is an air supply pipe extending in the width direction above the aeration gas 3 and allowing airtight communication between the insides of the aeration gases 3. a tube 7; Also, the air from the blower B is supplied to the header pipe 7 through the air pipe 8 .

As shown in FIGS. 1a and 1b, the aeration unit AU has the aeration gas 3 arranged over the entire width in the width direction, and arranged in parallel at equal intervals and line symmetrical with respect to the central axis CL in the length direction. There are a full-width aeration unit 4, a partial aeration unit 5a in which the aeration gas 3 is unevenly distributed on one side in the width direction, and a partial aeration unit 5a' in which the direction of uneven distribution of the aeration gas 3 is opposite to that of the partial aeration unit 5a. The full width aeration unit 4 and the partial aeration unit 5a are arranged side by side along the length direction of the aeration tank 2. As shown in FIG. In the first embodiment, the full-width aeration units are arranged in line symmetrically and at equal intervals with respect to the central axis CL. good. For example, they may not be line-symmetrical with respect to the central axis CL, and may not be arranged side by side at regular intervals.

With this configuration, a downward flow space 6 in which no aeration is performed is formed in the plane of arrangement of the aeration device 1a. As shown in FIG. 1c, during aeration, when the upward flow due to aeration reaches the water surface and returns to the aeration device 1a as a downward flow, through this downward flow space 6, A water flow is also generated on the side of the aeration tank 2, making it possible to agitate the bottom of the aeration tank 2.

The ratio of the numbers of the full-width aeration units 4 and the partial aeration units 5a is not particularly limited, and the numbers of the full-width aeration units 4 and the partial aeration units 5a may be the same or different. From the viewpoint of securing the amount of aeration, it is preferable to install more full-width aeration units 4 than partial aeration units 5a.
Further, the arrangement of the full-width aeration units 4 and the partial aeration units 5a is not particularly limited, and they may be arranged alternately or randomly.

The position of the aerated gas in the partial aeration unit is not particularly limited. It may be unevenly distributed on the outside.

The partial aeration units 5a and 5a' in the first embodiment are configured to form the downward flow space 6 by making the length of the header pipe 7 shorter than that of the full width aeration unit 4, but the partial aeration unit may be configured by blocking the diffusion holes for a part of the aeration gas 3 of the full-width aeration unit.

Further, the essence of the present invention is to stop the aeration in a partial region of the aeration device arranged over substantially the entire surface of the aeration tank to form a downward flow space. A full-width aeration unit and a partial aeration unit may be configured as one piece. For example, the downward flow space may be formed by closing the diffuser holes at predetermined intervals using the aeration gas extending in the length direction of the aeration tank.

The position of the downward flow space 6 when the aeration device 1a is viewed from above is not particularly limited, and may be arranged randomly or regularly. From the viewpoint of forming a good downward flow, the downward flow spaces are preferably regularly arranged, and more preferably regularly arranged on both sides of the aeration tank 2 in the width direction. In addition, "regularly" means having a repeating structure in the length direction of the aeration tank 2 .

The size of the downflow space 6 is not particularly limited, but the length in the width direction of the downflow space with respect to the length in the width direction of the aeration tank is preferably 2/3 or less, and more preferably 1/3. 3 or less. In addition, the "length in the width direction of the downward flow space" indicates the length in the width direction of the area without an aeration device, as indicated by the double-headed arrow P in Fig. 1(b). When there are a plurality of descending spaces (for example, the "partial aeration unit 5b" in Fig. 3), the sum of them is used. The widthwise length of the downflow space with respect to the widthwise length of the " is represented by its average value.
Also, the total length of the downdraft space or spaces with respect to the length of the entire aeration device in the longitudinal direction of the aeration tank is preferably ⅓ or less. The "length of the downflow space" in the longitudinal direction of the aeration tank indicates the length of the region without the aerator, as indicated by the double-headed arrow Q in FIG. 1(b).

(Aeration gas)
The aeration gas 3 of the present invention is an aeration pipe made of a tubular member wrapped with a membrane having fine air diffusion holes through which air passes, and is also called a "membrane pipe type ultrafine bubble air diffusion pipe". The aeration gas 3 may be a diffuser tube made of porous synthetic resin or ceramic, or an aeration pipe made of a tubular member such as a flexible tube provided with a large number of slits. Also, the aeration gas 3 may be an aeration plate made of a plate-shaped member such as a rectangular or round shape.

[Second embodiment]
FIG. 2 is a schematic explanatory diagram showing the water treatment system of the second embodiment of the present invention. FIG. 2(a) is a plan view of the water treatment system of the second embodiment of the present invention, and FIG. 2(b) is a side view of the water treatment system of the second embodiment of the present invention. (II-II arrow view in Fig. 2a)
In the aeration apparatus 1b of the second embodiment, instead of the partial aeration unit 5a of the first embodiment, a partial aeration unit 5b in which the aerated gas 3 is unevenly distributed on the center side in the width direction is provided. . The aeration device 1b is arranged so that the full width aeration unit 4 and the partial aeration unit 5b are alternately extended in the length direction of the aeration tank 2. As shown in FIG.

As shown in FIG. 2a, downdraft spaces 6 formed by full-width aeration units 4 and partial aeration units 5b will be provided regularly in the plane of installation of the aerator 1b. According to this aeration device 1b, a water flow is generated at regular intervals under the installation surface of the aeration device 1b, and the bottom of the aeration tank 2 can be constantly agitated.

[Third embodiment]
FIG. 3 is a schematic explanatory diagram showing a water treatment system according to a third embodiment of the invention. Fig.3 (a) is a top view of the water treatment system of 3rd Embodiment of this invention, FIG.3(b) is a side view of the water treatment system of 3rd Embodiment of this invention. (View from the arrow III-III in Fig. 3a)
In the aeration device 1c of the third embodiment, in addition to the full width aeration unit 4 and the partial aeration unit 5b of the second embodiment, the aeration gas 3 is unevenly distributed on both sides of the width direction aeration tank wall surface. It has an aeration unit 5c. The aeration device 1c is arranged so that the full-width aeration unit 4 and the partial aeration units 5b, 5c extend in the longitudinal direction of the aeration tank 2. As shown in FIG. 3a, the full width aeration unit 4, the partial aeration unit 5b, the full width aeration unit 4, the partial aeration unit 5c, and the full width aeration unit 4 are arranged.

As shown in FIG. 3a, downdraft space 6 formed by full-width aeration unit 4 and partial aeration units 5b, 5c is provided on both sides of the longitudinal central axis CL side of aeration tank 2 and the wall surface of aeration tank 2. It will be. According to this aeration device 1c, the downward flow from the longitudinal center axis CL side of the aeration tank 2 and the downward flow from the wall surface side are guided to the lower side of the aeration device 1c, making it possible to agitate the bottom of the aeration tank 2. do.

[Method for improving water treatment system]
The method for improving a water treatment system of the present invention is an existing water treatment system in which an aeration device is provided over substantially the entire surface of an aeration tank. A portion of the aeration tank is configured to be a partial aeration unit in which the aeration gas is arranged in a portion of the aeration tank in the width direction, so that a downward flow space through which the downward flow due to aeration passes is formed on the arrangement surface of the aeration device. Just do it.
Specifically, in an existing aeration device in which the aerated gas is evenly distributed in the width direction, part of the aerated gas is removed or a part of the aeration is stopped so that the downward flow space is formed. You should do it like this.
According to this water treatment system improvement method, in an existing water treatment system equipped with a full aeration type aeration device, there is no need to install a new attached device and replace all of the existing aeration device, and the aeration tank It can be a water treatment system with an aerator capable of sufficient agitation at the bottom.

<Simulation of flow velocity at the bottom of the aerator>
A bottom flow velocity simulation was performed for the water treatment system of the present invention. The arrangement of the aeration unit AU followed the second embodiment, and the simulation was performed with ten aeration gases 3 constituting the aeration unit AU. The results are shown in FIG. 4a.
In addition, FIG. 4b shows the results of a bottom flow velocity simulation in a conventional full-surface aeration type aeration apparatus in which the aerated gas is evenly distributed. In this simulation, the number of aeration gases in Figures 4a and 4b is the same.

The simulation was performed using ANSYS general-purpose fluid simulation software "Fluent". The calculation result shown in FIG. 4 is the result of execution for an aeration tank width of 5.5 m, tank length of 8.6 m, tank water depth of 5.0 m, and aeration equipment installed water depth of 4.0 m, but it is only an example. It does not limit the shape of the tank, the depth of water in which the aerator is installed, the layout of the aerator, or the like.

From FIG. 4a, in the water treatment system of the present invention, at the bottom of the aeration tank 2, from the lower side of the downward flow space 6 on the wall side of the aeration tank 2 toward the longitudinal central axis CL of the aeration tank 2, It can be seen that a flow is formed. On the other hand, from FIG. 4b, it can be seen that the flow at the bottom of the aeration tank 2 does not have a constant direction in the conventional aerator.

FIG. 5 shows a graph comparing bottom average flow velocities in the water treatment system of the second embodiment of the present invention and in a conventional water treatment system provided with a full aeration type aerator.
Comparing the average bottom flow velocities, the bottom average flow velocity in the aerator of the present invention was 2.2 times higher than that in the conventional full aeration type aerator.

From the results of Figures 4 and 5, in a full-surface aeration type aeration device equipped with an aeration unit consisting of a plurality of aeration gases, by providing a downflow space through which the downflow due to aeration passes, sufficient speed can be achieved at the bottom of the aeration tank. A unidirectional flow of water is generated, enabling effective agitation in the aeration tank.

INDUSTRIAL APPLICABILITY The water treatment system of the present invention can be used in aerobic microbial treatment tanks for organic sludge in sewage treatment plants and organic wastewater in food factories, pharmaceutical factories and the like, and methods for treating the same.

The method for improving the water treatment system of the present invention can provide a method for introducing the water treatment system of the present invention using an existing aerator.

1a, 1b, 1c aerator, 2 aeration tank, 3 aeration gas, 4 full width aeration unit, 5a, 5a', 5b, 5c partial aeration unit, 6 downflow space, 7 header pipe, 8 air pipe, 10 water treatment system , AU aeration unit, Hu upper haunch, Hs lower haunch, B blower, W treated water

Claims (2)

A method for improving an existing water treatment system having an aeration device substantially over the entire surface of the aeration tank, wherein the aeration is performed by removing the aeration gas from a full-width aeration unit in which the aeration gas is arranged substantially across the width of the aeration tank. A partial aeration unit in which the aeration gas is arranged partially in the width direction of the tank ,
A method for improving a water treatment system, wherein the partial aeration unit comprises an aeration gas arranged unevenly on both sides of the aeration tank wall surface in the width direction of the aeration tank . A method for improving an existing water treatment system having an aeration device substantially over the entire surface of the aeration tank, wherein in a full-width aeration unit in which the aeration gas is arranged substantially in the width direction of the aeration tank, air is supplied to a part of the aeration gas. By stopping the
A method for improving a water treatment system, wherein the partial aeration unit comprises aeration gas unevenly distributed on both sides of the wall surface of the aeration tank in the width direction .

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