JP7410751B2 - How to rebuild an oxidation ditch tank - Google Patents

Description

The present invention relates to a method for remodeling an oxidation ditch tank.

In the treatment of water to be treated such as sewage and sewage, an oxidation ditch method is known in which nitrification and denitrification are carried out in an endless waterway. In the oxidation ditch method, a stirring aeration device is installed at one or several locations of a reaction tank (hereinafter also referred to as an "oxidation ditch tank") consisting of an endless flow path in which the water to be treated circulates, and the water to be treated is stirred and aerated. This adjusts the conditions for nitrification or denitrification.

Treatment of treated water using the oxidation ditch method has advantages such as less amount of sludge generated and easier maintenance compared to other treatment methods of treated water, and is widely used. There is. Regarding the construction of the oxidation ditch tank used in the oxidation ditch method, methods are known such as methods using concrete pouring work in which concrete is poured into formwork assembled on site, and methods using a combination of precast concrete members.

For example, Patent Document 1 discloses that a circulation tank (oxidation ditch tank) used in the oxidation ditch method is formed by combining a plurality of U-shaped and/or box-shaped precast concrete members, and that the circulation tank is It is described that the straight flow path portion of the circulation tank is a rectangular member, and the curved flow path portion of the circulation tank is a trapezoidal or fan-shaped member.

Japanese Patent Application Publication No. 2004-249163

As described in Patent Document 1, it is known that by combining oxidation ditch tanks into parts, it is possible to increase the degree of freedom in design, simplify on-site work during assembly, and reduce construction costs. There is.

On the other hand, in recent years, due to population decline and depopulation in some areas, the amount of water flowing into oxidation ditch tanks that are already in operation has decreased, and the appropriate treatment capacity that was designed at the time of construction has not been met. The current situation is that there is no such thing. For this reason, treatment equipment such as a stirring aerator must be driven for water to be treated that is less than the appropriate treatment capacity in the oxidation ditch tank, resulting in problems such as excessive power consumption.

However, as described in Patent Document 1, it is known that the work cost at the time of designing and constructing an oxidation ditch tank can be reduced, and the construction cost can be reduced. On the other hand, no progress has been made in considering structural changes to the oxidation ditch tank itself in order to cope with the decrease in the amount of inflowing water to be treated. In particular, in the current situation where the decrease in the amount of inflow of treated water is thought to be due to population decline and depopulation, it is not expected that the amount of inflow of treated water will increase in the future. There is a need to consider appropriate renovations.

An object of the present invention is to provide a method for remodeling an oxidation ditch tank that can appropriately remodel an existing oxidation ditch tank where the amount of inflow water has changed so as to enable optimal operation. .

As a result of intensive study on the above-mentioned issues, the inventor of the present invention established a new endless flow path by providing a partition wall according to the capacity of the endless flow path in the oxidation ditch tank when renovating an existing oxidation ditch tank. The present invention was completed based on the discovery that by doing so, it becomes possible to remodel the oxidation ditch tank into an oxidation ditch tank that can be operated optimally with respect to the amount of inflow water.
That is, the present invention is the following method for remodeling an oxidation ditch tank.

A method for renovating an oxidation ditch tank according to the present invention to solve the above problems is a method for renovating an oxidation ditch tank, in which the capacity of the endless flow path of the oxidation ditch tank is adjusted according to the amount of inflow water to be treated. a capacity determination step for determining the capacity of the existing endless flow path, a partition wall installation step for installing a partition wall in the existing endless flow path so that the size of the endless flow path is determined according to the capacity of the endless flow path determined in the capacity determination step; and an intermediate wall removing step of removing a part of the intermediate wall disposed in the flow path, and the intermediate wall removed in the intermediate wall removing step is an end portion on the partition wall side.
According to this oxidation ditch tank renovation method, the capacity of the required endless flow path is determined in advance according to the amount of inflow water to be treated, and the capacity of the existing endless flow path is determined in advance according to the capacity of the endless flow path. By providing a partition wall in the channel and removing a portion of the intermediate wall of the endless flow path, it becomes possible to easily form an endless flow path with a new capacity. This makes it possible to optimize the capacity of the oxidation ditch tank for the amount of inflowing treated water, optimizing the treatment of treated water without using excessive electricity, and reducing the amount of treated water discharged. It becomes possible to stabilize water quality.

Furthermore, one embodiment of the oxidation ditch tank renovation method of the present invention is characterized in that an existing stirring aerator is used in the new endless flow path partitioned by the partition wall installation step.
According to this feature, by changing only the capacity of the endless flow path in the oxidation ditch tank and using the existing stirring aerator as is, it is possible to simplify the renovation work and reduce the renovation cost. Become.

In addition, in one embodiment of the stirring aeration system of the present invention, if two or more existing stirring aerators are provided, the existing stirring aerator is The oxidation ditch according to claim 1 or 2, characterized in that the stirring aeration machine is relocated or a new stirring and/or aeration machine having a function according to the capacity of the new endless flow path is installed. How to renovate a tank. It has the following characteristics.
According to this feature, a stirring aerator can be installed in the space formed in the new endless flow path by removing the intermediate wall, and it is possible to increase the treatment efficiency of the water to be treated in the new endless flow path. can. At this time, by relocating the existing stirring aerator, it becomes possible to reduce the initial cost related to the stirring aerator. Alternatively, by installing a new stirring and/or aeration machine with functions according to the capacity of the new endless flow path, it is easy to optimize the treatment of the water to be treated using the new endless flow path. becomes.

Further, an embodiment of the oxidation ditch tank renovation method of the present invention is characterized in that one region of the existing endless flow path divided by the partition wall installation step includes a sludge treatment step for performing sludge treatment. has.
According to this feature, by reducing the size of the existing oxidation ditch tank with a partition wall, the remaining area can be used as a space for sludge treatment, making it possible to effectively utilize the facility. In particular, since treatment of sludge generated during the wastewater treatment process can be carried out in an adjacent space, it is possible to reduce the running cost of the entire wastewater treatment.

Further, an embodiment of the oxidation ditch tank renovation method of the present invention includes a seismic reinforcement step for seismically reinforcing the new endless flow path formed by the partition wall installation step and the intermediate wall removal step. It has the following characteristics.
According to this feature, by performing seismic reinforcement, the strength of a new endless flow path that has changed from the design structure of the existing endless flow path by installing a partition wall or removing an intermediate wall can be improved. It becomes possible to maintain This allows the oxidation ditch tank to be renovated more appropriately.

According to the present invention, it is possible to provide a method for renovating an oxidation ditch tank that can appropriately renovate an existing oxidation ditch tank in which the amount of inflow water has changed so as to enable optimal operation. .

FIG. 1 is a schematic explanatory diagram showing the structure of an existing oxidation ditch tank according to the first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows the structure of the existing stirring aerator in the 1st embodiment of this invention. FIG. 1 is a schematic explanatory diagram showing the structure of a renovated oxidation ditch tank in the first embodiment of the present invention. FIG. 3 is a flow diagram related to the renovation of the oxidation ditch tank according to the first embodiment of the present invention. It is a schematic explanatory drawing which shows the structure of the oxidation ditch tank after renovation in the 2nd embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the oxidation ditch tank after renovation in the 3rd embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the method for remodeling an oxidation ditch tank according to the present invention will be described in detail with reference to the drawings.
Note that the structure of the oxidation ditch tank described in the embodiments is merely exemplified to explain the method for remodeling an oxidation ditch tank according to the present invention, and is not limited thereto. Furthermore, the steps related to the renovation of the oxidation ditch tank described in the embodiments are merely exemplified to explain the method of rebuilding the oxidation ditch tank according to the present invention, and are not limited thereto.

The method for renovating an oxidation ditch tank of the present invention relates to a method for renovating an existing oxidation ditch tank in which water to be treated is biologically treated using microorganisms in sludge. In particular, the present invention is suitable for an existing oxidation ditch tank that is equipped with a stirring aerator that performs stirring and aeration in an endless flow path, and processes water to be treated that involves nitrification or denitrification. can be used.

The water to be treated in the oxidation ditch tank of the present invention is not particularly limited, but includes organic wastewater such as sewage, agricultural community wastewater, livestock wastewater, and industrial wastewater. In particular, the present invention is suitable for the renovation of oxidation ditch tanks for treating sewage, agricultural village wastewater, etc., where the amount of inflow into treatment facilities is decreasing compared to the past due to factors such as population decline and depopulation. can be used.

[First embodiment]
(Structure of oxidation ditch tank)
FIG. 1 is a schematic explanatory diagram showing the structure of an existing oxidation ditch tank according to the first embodiment of the present invention. Moreover, FIG. 2 is a schematic explanatory diagram showing the structure of an existing stirring aerator in the first embodiment of the present invention.

As shown in FIG. 1, the existing oxidation ditch tank 1 in this embodiment includes a reaction tank 2 that has an oval shape in plan view, and an intermediate wall 3 extending in the longitudinal direction at the center of the reaction tank 2. is installed. The area around this intermediate wall 3 is an endless flow path 4 that is an endless circulation waterway. Water to be treated such as sewage W0 is introduced into the endless flow path 4 through an inlet 2a, and treated water W1 that has been treated in the endless flow path 4 is introduced from the endless flow path 4 through an outlet. 2b. The arrangement of the inlet 2a and the outlet 2b shown in FIG. 1 is an example, and is not limited to the arrangement shown in FIG. Note that the thick arrow in FIG. 1 indicates the flow direction of the water to be treated W0.

The oxidation ditch tank 1 includes a stirring aerator 20 that stirs and aerates the water W0 to be treated in the reaction tank 2, and the stirring aerator 20 is arranged at both ends of the intermediate wall 3 of the reaction tank 2. Note that although the stirring aerator 20 in this embodiment is shown as a vertical shaft type stirring aerator, it is not limited to this. Examples of the stirring aerator 20 include a vertical shaft type, a horizontal shaft type, and an oblique shaft type.

FIG. 2 is a schematic explanatory diagram showing an example of the structure of the stirring aerator 20 in this embodiment. As shown in FIG. 2, the stirring aerator has a shaft 21 that extends in the vertical direction and rotates around an axis, and a plurality of blade-shaped impellers 22 are provided at the lower end of the shaft 21. . Further, the impeller 22 is attached radially from the outer peripheral surface of the shaft 21.

The stirring aerator 20 includes an impeller rotation motor 23 as a drive source for rotating the impeller 22 . The means for controlling the drive of the motor 23 is not particularly limited. As a driving means for the motor 23, for example, as shown in FIG. 2, an inverter 24 that controls the rotation speed of the motor 23 may be provided. The inverter 24 is configured to adjust the rotation speed of the motor 23 by converting the current supplied from the power source into an alternating current of a predetermined frequency, and the rotation of the impeller 22 can be easily controlled.

Further, as shown in FIG. 2, the stirring aerator 20 may include a lifting device 25 that rotatably supports the shaft 21 and allows the shaft 21 to be raised and lowered. Thereby, the position of the impeller 22 relative to the water to be treated W0 in the reaction tank 2 is controlled, and switching between aerobic operation and anaerobic operation, which will be described later, is possible.

In the oxidation ditch tank 1 of this embodiment, two stirring aerators 20a, 20b are provided, and each stirring aerator 20a, 20b is arranged at both ends of the intermediate wall 3 of the reaction tank 2. The amount of water to be treated W0 in the reaction tank 2 is adjusted so that the impeller 22 is immersed therein, and the water is rotated counterclockwise in the reaction tank 2 (in FIG. arrow).

In the oxidation ditch tank 1, an aerobic operation in which the inside of the reaction tank 2 is brought into an aerobic state and an anoxic operation in which the inside of the reaction tank 2 is put in an anaerobic state are alternately performed. During aerobic operation, as shown in FIG. 2, the rotation speed of the impeller 22 of the stirring aerator 20 is increased to generate appropriate droplets D, and air is supplied to the water to be treated W0 for aeration. During anoxic operation, the impeller 22 is lowered to reduce the number of revolutions and stir the water to be treated W0. In this way, an aerobic state or an anaerobic state can be formed in the reaction tank 2 depending on the degree of immersion of the impeller 22 of the stirring aerator 20 into the water to be treated W0 and the rotation speed.

On the other hand, when the amount of inflow of the water to be treated W0 decreases, it becomes difficult to adjust the aerobic operation of the water to be treated W0 by the stirring aerator 20. As the stirring aerator 20, one having functions such as an output that matches the originally expected inflow amount of the water to be treated W0 is arranged. Therefore, due to the decrease in the amount of inflow water W0 to be treated, the existing stirring aerator 20 becomes so-called over-specified, and excessive power is consumed in driving the impeller 22 for aerobic operation and anaerobic operation. A problem arises in that it becomes difficult to perform optimal operation in processing the treated water W0.

The oxidation ditch tank renovation method of this embodiment is applied to the existing oxidation ditch tank as described above. This makes it possible to appropriately renovate the existing oxidation ditch tank 1 in response to a decrease in the amount of inflow water W0 to be treated, and to optimize the treatment of water W0 to be treated.

FIG. 3 is a schematic explanatory diagram showing the structure of the oxidation ditch tank after renovation in the first embodiment of the present invention. Note that FIGS. 3A and 3B illustrate the structure of the partition wall 5.
As shown in FIG. 3, the renovated oxidation ditch tank 10 of this embodiment is constructed by providing a partition wall 5 in the reaction tank 2 described above and removing a part of the intermediate wall 3. An endless flow path 40 is formed. Note that the description of structures similar to the existing oxidation ditch tank 1 shown in FIG. 1 will be omitted.

The partition wall 5 is installed in the reaction tank 2 by a partition wall installation step described later.
The material and structure of the partition wall 5 are not particularly limited as long as they can partition the reaction tank 2 and form a new endless flow path 40 stably. Examples of the material for the partition wall 5 include concrete, metal, and plastic, as well as the same materials as the reaction tank 2 and the intermediate wall 3. In addition, as for the structure of the partition wall 5, for example, as shown in FIG. 3A, in addition to having a curved surface such as an arc shape and having a curved surface when viewed from above, as shown in FIG. 3B, a rectangular shape , linear, polygonal, etc., which have a straight surface when viewed from above. When the structure of the partition wall 5 is made of a curved line such as an arc, there is an effect that the flow in the new endless flow path 40 can be smoothed. On the other hand, when the structure of the partition wall 5 is a rectangular structure having a linear surface, the structure is relatively simple and the installation is easy, so that it is possible to reduce the cost of renovation. In particular, when the partition wall 5 is made linear, there is an advantage that the strength of the new endless flow path 40 is strong.

A part of the intermediate wall 3 is removed in an intermediate wall removal step described later. At this time, the intermediate wall 3 to be removed is a location close to the newly provided partition wall 5 side (the end portion on the partition wall 5 side). As a result, as shown in FIG. 3, a part of the reaction tank 2, the partition wall 5, and the partially removed intermediate wall 3 form an endless flow path 40, which is a new circulation waterway. In addition, without removing the structure related to the reaction tank 2, just by dividing the inside thereof with the partition wall 5, it is possible to easily form the endless flow path 40 according to the inflow amount of the water to be treated W0. becomes.

Regarding the removal of the intermediate wall 3, it is sufficient that a new endless flow path 40 is formed, and there are no particular limitations on the removal means and the size of the removed location. For example, as will be described later, when installing a stirring and aeration device (stirring and/or aeration machine) in a space where the intermediate wall 3 has been removed, the intermediate wall 3 is removed so that the device that performs stirring and aeration can be installed. For example, determining the size of .

In the new endless flow path 40 formed by installing the partition wall 5 and removing the intermediate wall 3, as shown in FIG. 3, it is possible to use the existing stirring aerator 20a as is. In the new endless flow path 40, since a certain amount of inflow water is secured, it becomes possible to fully demonstrate the function of the existing stirring aerator 20a. In addition, by using the existing stirring aerator 20a, the renovation work is simplified, and since a new stirring aerator is not required, the initial cost of equipment can be reduced, and the oxidation ditch tank It becomes possible to reduce costs related to renovation.

Further, the space formed by removing the intermediate wall 3 may be used as a flow path as it is, but as shown in FIG. 3, it is preferable to provide a space for stirring and aeration. Thereby, it becomes possible to effectively form the flow of the water to be treated W0 in the new endless flow path 40 and to improve the processing efficiency of the water to be treated W0.

At this time, one example of providing a stirring aeration device in the space formed by removing the intermediate wall 3 is to relocate the existing stirring aerator 20b. As a result, a new stirring aerator is not required, so the initial cost of equipment can be reduced, and the cost of rebuilding the oxidation ditch tank can be reduced.

Another example of installing a stirring and aeration device in the space formed by removing the intermediate wall 3 is a stirring and/or aeration device having a function corresponding to the capacity of the new endless flow path 40. One example is the establishment of a new facility. This makes it easy to optimize the treatment of the water to be treated W0 by the new endless flow path 40. In particular, in the new endless flow path 40, the flow path is shorter than the existing endless flow path 4. There is also a possibility that stirring and aeration of the treated water W0 will proceed. Therefore, equipment specialized only for stirring or aeration (stirrer or aerator) may be installed in the space created by removing the intermediate wall 3, and may be installed as auxiliary equipment for the existing stirring aerator 20a. . This makes it possible to reduce the initial cost and running cost of a newly installed agitator or aerator.

When using the existing stirring aerators 20a and 20b in the new endless flow path 40, the total volume of the water to be treated W0 is reduced compared to the existing endless flow path 4. For this reason, if the existing stirring aerators 20a and 20b are driven in the same way as the drive control in the existing endless flow path 4, there is a possibility that the new endless flow path 40 will be over-specified. At this time, as described above, it is preferable that the stirring aerators 20a, 20b are provided with an inverter 24 to control the rotation speed of the impeller 22. Thereby, it becomes possible to easily perform stirring and aeration according to the capacity of the new endless flow path 40.

(oxidation ditch tank renovation process)
FIG. 4 is a flow diagram showing the steps involved in rebuilding the oxidation ditch tank in this embodiment.
With reference to FIG. 4, a process of converting an existing oxidation ditch tank 1 into an oxidation ditch tank 10 will be described.

First, as a capacity determination step, based on data regarding the amount of inflow water W0 to be treated flowing into the reaction tank 2 (endless flow path 4) of the existing oxidation ditch tank 1, an endless flow path suitable for the oxidation ditch tank is determined. Determine the volume of the flow path.

At this time, the type and acquisition means of data regarding the amount of inflow water W0 to be treated in the existing oxidation ditch tank 1 are not particularly limited. Examples include using records (such as handwritten numbers or data values) based on monitoring (visual observation) such as daily inspections by workers, and using observation records from a water meter installed in the reaction tank 2. Another example is to use data that predicts the amount of inflow of the water to be treated W0 based on information regarding the source of the water to be treated W0 (number of population, number of households, number of factories in operation, etc.).
Furthermore, there are no particular limitations on the number or acquisition period of data regarding the amount of inflow water of the water to be treated W0. However, in view of the scale of the renovation of the oxidation ditch tank, it is preferable to obtain data on the amount of inflowing water W0 to be treated on a monthly or annual basis and to use the changes in this data as the basis.

Based on the obtained data regarding the inflow amount of the water to be treated W0, the means for determining the suitable capacity for the endless flow path is not particularly limited, and can be determined in the same manner as in the design of a conventional oxidation ditch tank. As a means for determining the capacity of the endless flow path, for example, it may be determined based on past operating results, or it may be determined based on various calculation formulas related to the design of the oxidation ditch tank. good.

After a suitable capacity for the endless flow path is determined in the capacity determination step, a step for changing the capacity of the endless flow path 4 of the existing oxidation ditch tank 1 is performed (see FIG. 4A). As shown in FIG. 4A, the steps for changing the capacity of the endless flow path 4 include a partition wall installation step and an intermediate wall removal step, but these steps change the capacity of the endless flow path 4. There is no particular limitation on the order in which both steps are performed, as long as the process is changed and the endless flow path 40 in the renovated oxidation ditch tank 10 is formed.

As a partition wall installation step, a partition wall 5 is provided in the endless flow path 4 of the existing oxidation ditch tank 1. At this time, the partition wall 5 is arranged so that the new endless flow path 40 partitioned by the partition wall 5 has a size that satisfies the capacity determined in the capacity determination step.
The means for arranging the partition wall 5 is not particularly limited. For example, the partition wall 5 may be constructed within the endless flow path 4, or the partition wall 5 manufactured outside the system may be incorporated into the endless flow path 4.

Further, in the intermediate wall removal step, the end of the intermediate wall 3 on the partition wall 5 side in the existing oxidation ditch tank 1 is removed. The removal means and removal range of the intermediate wall 3 are not particularly limited as described above.

Through the above steps, as shown in FIG. 4B, an endless flow path 40, which is a new circulation waterway, is formed by a part of the reaction tank 2, the partition wall 5, and the partially removed intermediate wall 3. Ru. Note that, as shown in FIG. 4B, in the oxidation ditch tank 10 after the renovation, the inlet 2a and the outlet 2b are included in the new endless flow path 40, but the existing oxidation ditch tank Depending on the arrangement of the inlet 2a and the outlet 2b of 1, they may not be included in the new endless flow path 40. In that case, a new inlet or outlet shall be provided for the new endless flow path 40.

Further, as shown in FIG. 4B, the stirring aerator 20b may be relocated to the space formed by the intermediate wall removal step. Thereby, the endless flow path 4 of the existing oxidation ditch tank 1 is shortened to the endless flow path 40, and it becomes possible to effectively utilize the existing stirring aerators 20a and 20b.

As described above, according to the method for renovating an oxidation ditch tank in this embodiment, the capacity of the required endless flow path is determined in advance according to the amount of inflow water to be treated, and the capacity of the endless flow path is determined in advance. By installing a partition wall in the existing endless flow path and removing a portion of the intermediate wall of the endless flow path, it becomes possible to easily create an endless flow path with a new capacity. . This makes it possible to optimize the capacity of the oxidation ditch tank for the amount of incoming treated water, optimize the treatment of treated water without using excessive electricity, and optimize the treatment of treated water that is discharged. It becomes possible to stabilize water quality.

[Second embodiment]
FIG. 5 is a schematic explanatory diagram showing the structure of a renovated oxidation ditch tank according to the second embodiment of the present invention. Note that description of the same components as in the first embodiment will be omitted.

The oxidation ditch tank renovation method in the second embodiment includes, in addition to the steps related to the renovation method in the first embodiment, sludge in the other region of the new endless flow path 40 partitioned by the partition wall 5. It is equipped with a sludge treatment step for performing treatment. More specifically, as shown in FIG. 5, the oxidation ditch tank 11 after the renovation has a part ( A sludge treatment area R) is provided, and sludge treatment is performed in this sludge treatment area R.

As shown in FIG. 5, the renovated oxidation ditch tank 11 in this embodiment processes the treated water W0 in the new endless flow path 40, and then sends the treated water W1 through the outlet 2b to sedimentation outside the system. After being discharged to a treatment facility (sedimentation tank 6), the sludge S separated in the sedimentation tank 6 is introduced into the sludge treatment area R. In addition, although FIG. 5 shows that the sludge S is introduced into the sludge treatment area R via the settling tank 6, the present invention is not limited to this. As another example, for example, the endless flow path 40 may be provided with a collection mechanism and a discharge port for the sludge S, and the sludge S collected in the endless flow path 40 may be directly introduced into the sludge treatment region R.

As a sludge treatment step, the introduced sludge S is treated in the sludge treatment region R. Note that the specific treatment means performed in the sludge treatment region R is not particularly limited. For example, for the sludge S introduced into the sludge treatment area R, heating means such as an air blower or a heat source may be provided to dry the sludge S, or the sludge S in the sludge treatment area R may be treated with microorganisms and carriers. An example of this is to reduce the volume of sludge by adding such substances. Note that the sludge treatment region R formed by dividing the existing oxidation ditch tank 1 with the partition wall 5 is a space having a relatively large area and a large capacity. For this reason, a process in which microorganisms, carriers, etc. are mixed with the sludge S and progresses over time is preferable from the viewpoint of effective use of space and energy saving, rather than a process in which energy is supplied from the outside, such as by blowing air or heat from a heat source.

As described above, the oxidation ditch tank renovation method in this embodiment includes a sludge treatment step that performs sludge treatment, and the area remaining after reducing the size of the existing oxidation ditch tank with a partition wall is used for sludge treatment. By creating a space where activities can be carried out, it becomes possible to make effective use of the facility. In particular, since treatment of sludge generated during the wastewater treatment process can be carried out in an adjacent space, it is possible to reduce the running cost of the entire wastewater treatment.

[Third embodiment]
FIG. 6 is a schematic explanatory diagram showing the structure of a renovated oxidation ditch tank according to the third embodiment of the present invention. Note that description of the same components as in the first embodiment will be omitted.

The oxidation ditch tank renovation method in the third embodiment includes, in addition to the steps related to the renovation method in the first embodiment, a seismic reinforcement step for seismically reinforcing the new endless flow path 40. be. More specifically, as shown in FIG. 6, a reinforcing member 7 such as a beam is provided for the new endless flow path 40 in the oxidation ditch tank 12 after the renovation.

In the oxidation ditch tank 12 after renovation in this embodiment, as shown in FIG. 5 installation etc. Therefore, since the structure of the oxidation ditch tank 1 has changed from the original design, the strength of the oxidation ditch tank 12 after renovation may differ from the strength of the conventional structure. Therefore, by providing the reinforcing member 7 in the new endless flow path 40 as an earthquake reinforcement step, sufficient strength can be maintained in the oxidation ditch tank 12 after the renovation.

The seismic reinforcement step may be any step that can sufficiently maintain the strength of the oxidation ditch tank 12 after renovation. For example, as shown in FIG. 6, a reinforcing member 7 may be provided near the partition wall 5 of the new endless flow path 40 so as to be orthogonal to the intermediate wall 3. Further, as another example, the reinforcing member 7 and the intermediate wall 3 may be provided so as to be diagonal to each other. Furthermore, the material and number of the reinforcing members 7 are not particularly limited, and it is preferable to design and arrange them so as to obtain the required strength in accordance with laws and regulations regarding seismic strength.

As described above, the method for rebuilding the oxidation ditch tank in this embodiment is to change the design structure of the existing endless flow path by performing seismic reinforcement, installing partition walls, and removing intermediate walls. It is also possible to maintain the strength of the new endless flow path. This allows the oxidation ditch tank to be renovated more appropriately.

In addition, the embodiment mentioned above shows an example of the renovation method of an oxidation ditch tank. The method for renovating an oxidation ditch tank according to the present invention is not limited to the embodiments described above, and the method for renovating an oxidation ditch tank according to the embodiments described above is applicable without changing the gist of the claims. May be deformed.

For example, in the oxidation ditch tank renovation method of this embodiment, in order to adjust the capacity of the new endless flow path, in addition to partitioning the endless flow path with partition walls, a non-water permeable structure is added to the bottom of the endless flow path. It may also be a combination of providing different materials and raising the bottom. At this time, by making the water-impermeable material removable from the endless flow path, it becomes possible to easily adjust the capacity of the endless flow path.

Further, in the oxidation ditch tank renovation method of this embodiment, the area other than the new endless flow path may be used for purposes other than the sludge treatment area R. For example, it can be used as a storage facility for natural water (rainwater, groundwater, etc.) that does not require much treatment by taking advantage of its function as an aquarium. Thereby, it can be effectively used as a water source for cleaning the endless flow path, stirring aerator, etc., and for maintenance related to the equipment of the oxidation ditch tank.

Further, in the method for remodeling an oxidation ditch tank according to this embodiment, the steps shown in the second embodiment and the third embodiment may be combined. As a result, the oxidation ditch tank after renovation will be able to process sludge using the sludge treatment area, and will be seismically reinforced, allowing for more appropriate renovation of the oxidation ditch tank. becomes possible.

The oxidation ditch tank renovation method of the present invention is applied to the renovation of an existing oxidation ditch tank in which treated water is subjected to biological treatment using microorganisms in sludge. In particular, it is suitably used in the renovation of an existing oxidation ditch tank where the amount of inflowing water to be treated tends to be smaller than the appropriate amount of water at the time of design and construction.

1 Existing oxidation ditch tank, 10, 11, 12 Oxidation ditch tank after renovation, 2 Reaction tank, 2a Inlet, 2b Outlet, 20, 20a, 20b Stirring aerator, 21 Shaft, 22 Impeller, 23 Motor , 24 Inverter, 25 Lifting device, 3 Intermediate wall, 4 Existing endless flow path, 40 Endless flow path after renovation, 5 Partition wall, 6 Sedimentation basin, 7 Reinforcement member, D Splash, R Sludge treatment area, S Sludge, W0 Treated water, W1 Treated water

Claims (5)

A method for remodeling an oxidation ditch tank, the method comprising:
a capacity determination step of determining the capacity of the endless flow path of the oxidation ditch tank according to the amount of inflow of the water to be treated ;
a partition wall installation step of installing a partition wall in the existing endless flow path so that the size corresponds to the capacity of the endless flow path determined in the capacity determination step;
an intermediate wall removing step of removing a part of the intermediate wall disposed in the existing endless flow path,
A method for remodeling an oxidation ditch tank, wherein the intermediate wall removed in the intermediate wall removal step is an end portion on a partition wall side. The method for renovating an oxidation ditch tank according to claim 1, characterized in that an existing stirring aerator is used in the new endless flow path partitioned in the partition wall installation step. If two or more existing stirring aerators are installed, move the existing stirring aerator to the space of the new endless flow path formed in the intermediate wall removal step, or create a new endless flow path. 3. The method for renovating an oxidation ditch tank according to claim 1 or 2, comprising newly installing a stirring and/or aeration machine having a function according to the capacity of the tank. The oxidizer according to any one of claims 1 to 3, characterized in that, in the existing endless flow path partitioned by the partition wall installation step, one region is provided with a sludge treatment step for performing sludge treatment. How to rebuild a dation ditch tank. 5. The method according to claim 1, further comprising a seismic reinforcement step for seismically reinforcing the new endless flow path formed by the partition wall installation step and the intermediate wall removal step. The method for renovating the oxidation ditch tank described.