JP6802197B2 - Aeration agitation system - Google Patents

Description

The present invention relates to an aeration stirring system that aerates or agitates the water to be treated in the reaction vessel.

Conventionally, a vertical axis type mechanical aeration device has been adopted in an oxidation ditch that nitrifies and denitrifies water to be treated such as sewage in a circulating water channel (see, for example, Patent Document 1). This vertical axis type mechanical aeration device is connected to the vertical axis extending in the vertical direction, the impeller (stirring blade) attached to the lower end of the vertical axis, and the upper end of the vertical axis, and the vertical axis is the rotational force. It is equipped with a drive device for transmission. When the impeller rotates at a standard position near the gas-liquid interface, the water to be treated is scattered on the water surface, oxygen is supplied to the water to be treated, and the water to be treated is aerated. Further, by lowering the impeller into water and rotating it, the water to be treated can be efficiently agitated.

Japanese Unexamined Patent Publication No. 2004-290977

As the operation method of the conventional vertical axis type mechanical aeration device, there are a continuous operation method, an intermittent operation method (or an intermittent aeration operation method), a controlled operation method based on the dissolved oxygen amount, and the like. In the continuous operation type, continuous operation is performed by rotating the impeller at a constant rotation speed. In the intermittent operation method, the impeller was rotated as needed, and the impeller was stopped when it was not necessary. In the intermittent aeration operation method, the impeller is rotated at a high speed to supply oxygen, the impeller is rotated at a low speed to slowly stir the water to be treated, and the rotation speed of the impeller is alternately switched between high speed and low speed. In the continuous operation method, the intermittent operation method, and the intermittent aeration operation method, the amount of oxygen supplied to the water to be treated could not be adjusted according to the load fluctuation of the inflowing water to be treated.

In the controlled operation method based on the amount of dissolved oxygen, the dissolved oxygen concentration in the water to be treated, which is the control target, is set, and when the measured dissolved oxygen concentration is higher than the set value, the rotation of the impeller is reduced to oxygen. The amount of supply was reduced, and the number of revolutions of the impeller was increased when the measured amount of dissolved oxygen was lower than the set value. In such a controlled operation method based on the amount of dissolved oxygen, the operation is performed so as to keep the dissolved oxygen concentration in the reaction vessel constant even when the degree of pollution of the water to be treated is low and oxygen supply is unnecessary. There was room for reduction.

An object of the present invention is to provide an aeration agitation system capable of controlling operation in response to load fluctuations of inflowing water to be treated, stabilizing the water quality of the treated water, and saving energy.

In the aeration agitation system of the present invention, a reaction tank for vitrifying or denitrifying circulating water to be treated and an impeller having a vertical axis extending in the vertical direction and rotating around the axis and provided on the vertical axis are rotated for reaction. A vertical axis type mechanical aeration stirrer that aerates and agitates the water to be treated in the tank, a measuring unit that measures the amount of nitrogen in the water to be treated in the reaction tank, and a vertical axis based on the amount of nitrogen measured by the measuring unit. It is characterized by including a control unit for controlling the operation of the type mechanical aeration stirrer.

According to this aeration / stirring system, the amount of nitrogen in the water to be treated in the reaction vessel is measured by the measuring unit, and the control unit controls the operation of the vertical axis type mechanical aeration / stirring machine based on the measured amount of nitrogen. Thereby, the rotation speed of the impeller can be controlled according to the load of the water to be treated flowing into the reaction tank, and the amount of oxygen supplied to the water to be treated can be increased or decreased. Therefore, the aeration agitation system can adjust the oxygen supply amount as necessary to stabilize the water quality of the treated water, and when the oxygen supply is unnecessary, the rotation of the impeller can be suppressed, and the energy can be reduced. Consumption can be suppressed.

Here, the measuring unit measures the amount of ammoniacal nitrogen and the amount of nitrate nitrogen as the amount of nitrogen, and the control unit measures the amount of ammoniacal nitrogen in the aeration operation when the amount of ammoniacal nitrogen is equal to or higher than the first determination threshold value. The number of revolutions may be increased and the number of revolutions of the impeller may be decreased when the amount of ammoniacal nitrogen is less than the first determination threshold and the amount of nitrate nitrogen is equal to or greater than the second determination threshold. As a result, when the amount of ammoniacal nitrogen is equal to or higher than the first determination threshold value, the rotation speed of the impeller can be increased to increase the oxygen supply amount and promote nitrification. When nitrification of ammonia is promoted, ammonia in the water to be treated decreases and nitric acid increases. Further, the aeration agitation system reduces the rotation speed of the impeller to increase the oxygen supply amount when the amount of ammoniacal nitrogen is less than the first determination threshold value and the amount of nitrate nitrogen is equal to or more than the second determination threshold value. Can be reduced. As the amount of ammonia in the water to be treated decreases and the amount of nitric acid increases, the amount of oxygen supplied can be reduced to promote denitrification, and nitric acid can be converted into nitrogen gas. As a result, in the aeration stirring system, it is possible to control the operation according to the amount of ammoniacal nitrogen in the water to be treated to stabilize the water quality of the treated water and save energy.

Further, the measuring unit measures the amount of ammoniacal nitrogen as the amount of nitrogen, and the control unit increases the number of rotations of the impeller when the amount of ammoniacal nitrogen is equal to or higher than the first determination threshold value in the aeration operation. When the amount of ammoniacal nitrogen is less than the first determination threshold value, the number of rotations of the impeller may be reduced. As a result, when the amount of ammoniacal nitrogen increases, the rotation speed of the impeller is increased to increase the oxygen supply amount, and when the amount of ammoniacal nitrogen decreases, the rotation speed of the impeller is decreased to supply oxygen. The amount can be reduced.

Here, the measuring unit measures the amount of ammoniacal nitrogen as the amount of nitrogen, and the control unit rotates the impeller at the first rotation speed when the amount of ammoniacal nitrogen is equal to or higher than the upper limit value in the aeration operation. When the amount of ammoniacal nitrogen is less than the upper limit and is greater than or equal to the lower limit, the impeller is rotated at a second rotation speed less than the first rotation speed, and when the amount of ammoniacal nitrogen is less than the lower limit, the impeller is turned. It may be rotated at a third rotation speed lower than the second rotation speed. Thereby, the rotation speed of the impeller can be changed in three stages according to the amount of ammoniacal nitrogen, and the oxygen supply amount can be controlled.

In addition, the measuring unit measures the amount of ammoniacal nitrogen as the amount of nitrogen, and the control unit executes an aeration operation when the amount of ammoniacal nitrogen is equal to or greater than the lower limit, and the amount of ammoniacal nitrogen is less than the lower limit. In some cases, the aeration operation may be terminated and the anoxic operation may be performed. Thereby, the oxygen supply amount can be controlled according to the amount of ammoniacal nitrogen, and the control can be simplified.

According to the present invention, it is possible to provide an aeration agitation system capable of controlling the operation in response to the load fluctuation of the inflowing water to be treated, stabilizing the water quality of the treated water, and saving energy.

It is a schematic plan view which shows the oxidation ditch to which the aeration stirring system of one Embodiment of this invention was applied. It is a side view which shows the impeller of the vertical axis type mechanical aeration stirrer in FIG. It is a flowchart which shows the control procedure of the aeration agitation system which concerns on 1st Example. It is a flowchart which shows the control procedure of the aeration agitation system which concerns on 2nd Example. It is a flowchart which shows the control procedure of the aeration agitation system which concerns on 3rd Example. It is a flowchart which shows the control procedure of the aeration agitation system which concerns on 4th Example. It is a table which shows the operation state according to the amount of ammonia nitrogen and the amount of nitrate nitrogen at the time of aeration operation of the aeration stirring system which concerns on 4th Example. It is a flowchart which shows the control procedure of the aeration agitation system which concerns on 5th Example. It is a table which shows the operation state according to the amount of ammonia nitrogen and the amount of nitrate nitrogen at the time of aeration operation of the aeration stirring system which concerns on 5th Example. It is a schematic plan view which shows the oxidation ditch to which the aeration stirring system of one Embodiment of this invention was applied.

Hereinafter, embodiments of the oxidation ditch to which the aeration stirring system according to the present invention is applied will be described in detail with reference to the drawings.

The oxidation ditch 1 shown in FIG. 1 is used as a water treatment facility such as a small-scale sewage treatment plant. The oxidation ditch 1 includes a reaction tank 2 having an oval shape in a plan view, and a partition wall 3 extending in the longitudinal direction is arranged at the center of the reaction tank 2. The area around the partition wall 3 is an endless circulating water channel 4. Water to be treated such as sewage is introduced into the circulation water channel 4 through the introduction port 2a, and the treated water treated by the circulation water channel 4 is led out from the circulation water channel 4 through the outlet port 2b.

The oxidation ditch 1 includes a vertical axis type mechanical aeration stirrer 11 that aerates and agitates the water to be treated in the reaction tank 2, and the vertical axis type mechanical aeration stirrer 11 is arranged at the center of the reaction tank 2 in the longitudinal direction. Has been done. As shown in FIG. 2, the vertical axis type mechanical aeration stirrer 11 has a vertical axis 21 extending in the vertical direction and rotating around the axis, and an impeller 22 is provided at the lower end of the vertical axis 21. .. The vertical axis type mechanical aeration stirrer 11 has an impeller rotation electric motor as a drive source for rotating the impeller 22, a driving force transmission device for decelerating and transmitting the rotational driving force of the impeller rotation electric motor, and a vertical axis 21. It is equipped with a lifting device that can be rotatably supported and lifted. This elevating device has a cylinder as a drive source for elevating and lowering the vertical axis 21.

A plurality of blade-shaped impellers 22 (8 in this embodiment) are attached radially from the outer peripheral surface of the vertical axis 21. Each impeller 22 is provided with a cone-shaped plate 22a on the impeller facing surface as a side surface and a bent portion 22b on the upper portion thereof, so that the water to be treated can be easily agitated during rotation. During aerobic operation, the rotation speed of the impeller 22 is increased to generate appropriate droplets, and air is supplied to the water to be treated to aerate it. During anaerobic operation, the impeller 22 is lowered to reduce the rotation speed and stir the water to be treated.

The oxidation ditch 1 is provided with two vertical axis type mechanical aeration stirrers 11, and each vertical axis type mechanical aeration stirrer 11 is formed so as to sandwich the partition wall 3 of the reaction tank 2 and is arranged on the upstream side of the circulation water channel 4. Has been done. The amount of water to be treated in the reaction tank 2 is adjusted so that the impeller 22 is immersed, and the water is circulated in the reaction tank 2 counterclockwise according to the rotation of the impeller 22 driven by the impeller rotation motor.

In the oxidation ditch 1, an aerobic state is formed by rotating the impeller 22 near the water surface, and an anaerobic state is formed by lowering the impeller 22 into water and slowly rotating it.

The aeration / stirring system of the oxidation ditch 1 includes the above-mentioned reaction tank 2, a vertical axis type mechanical aeration / stirring machine 11, and an oxygen supply system 10 that controls oxygen supply into the reaction tank 2. The oxygen supply system 10 includes a nitrogen monitor (measuring unit) 12 that measures the amount of nitrogen in the water to be treated in the reaction vessel 2, and a vertical axis type mechanical aeration stirrer 11 based on the measurement results measured by the nitrogen monitor 12. It has a control panel 13 for controlling the operation of the above.

The nitrogen monitor 12 measures the amount of ammoniacal nitrogen (concentration of ammoniacal nitrogen) and the amount of nitrate nitrogen (concentration of nitrate nitrogen) as the amount of nitrogen in the water to be treated in the reaction vessel 2, respectively. Since the amount of nitrogen in the reaction vessel 2 is substantially uniform, the nitrogen monitor 12 may be arranged at any position in the reaction vessel 2. The detection signal detected by the nitrogen monitor 12 is transmitted to the control panel 13.

The control panel (control unit) 13 includes a CPU that performs arithmetic processing, a ROM and RAM that serve as a storage unit 17, an input signal circuit, an output signal circuit, a power supply circuit, and the like. In the control panel 13, the operating condition setting unit 14, the determination unit 15, and the control unit 16 are constructed by executing the program stored in the storage unit 17. A nitrogen monitor 12 and a vertical axis type mechanical aeration stirrer 11 are electrically connected to the control panel 13.

The operating condition setting unit 14 sets the operating conditions of the aeration agitation system based on, for example, an input operation by the operator. The operating conditions include one cycle time, aeration time, target value of ammonia nitrogen amount, aeration operation start time and the like. As other operating conditions, an upper limit of the amount of ammoniacal nitrogen, a lower limit of the amount of ammoniacal nitrogen, an upper limit of the amount of nitrate nitrogen, a lower limit of the amount of nitrate nitrogen, and the like may be set. The one-cycle time is the time of one cycle that is repeatedly executed, and is the total time of the aeration time and the anaerobic operation time. For example, when one cycle time is set to 4 hours, 6 cycles of operation are performed a day, and aeration operation and anaerobic operation are alternately executed 6 times each.

The determination unit 15 compares the value measured by the nitrogen monitor 12 with the target value (determination threshold value), and determines whether or not the amount of nitrogen in the water to be treated in the reaction vessel 2 is equal to or greater than the target value. Further, the determination unit 15 determines whether or not the operation time is less than the set aeration time, and also determines whether or not the operation time is less than the set one cycle time.

The control unit 16 controls the vertical axis type mechanical aeration stirrer 11 based on the result of the determination by the determination unit 15. The control unit 16 outputs a control signal to the vertical axis type mechanical aeration stirrer 11 to increase or decrease the rotation speed of the impeller 22. Further, by outputting a control signal to the vertical axis type mechanical aeration stirrer 11 and raising or lowering the impeller 22, switching between the aeration operation and the anaerobic operation is executed.

The storage unit 17 stores information regarding the operating conditions set by the operating condition setting unit 14. Further, the storage unit 17 stores the measured value by the nitrogen monitor 12.

Next, the control procedure (operation example) of the aeration agitation system will be described with reference to FIGS. 3 to 9.

(First Example)
FIG. 3 is a flowchart showing a control procedure of the aeration stirring system according to the first embodiment. First, the operating condition setting unit 14 sets the operating conditions of the aeration stirring system. The operating condition setting unit 14 sets, for example, one cycle time to 6 hours, an aeration time of 3 hours, and an aeration operation start time of 6 o'clock. The target value of the amount of ammoniacal nitrogen is determined according to the required water quality standard.

After the operating conditions are set, the aeration agitation system starts one cycle of operation (step S1), starts aeration operation (step S2), and starts measuring the operation time. The control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to arrange the impeller 22 near the water surface and rotate it at a predetermined rotation speed. As a result, oxygen is supplied to the water to be treated, and the inside of the reaction tank 2 is brought into an aerobic state.

Next, the determination unit 15 determines whether or not the operation time is less than the aeration time (step S3). If it is determined that the operating time is less than the aeration time (step S3: YES), the process proceeds to step S6, and if the operating time reaches the aeration time (step S3: NO), the process proceeds to step S4.

In step S6, the amount of nitrogen in the water to be treated is measured (step S6). The control panel 13 calculates the amount of ammoniacal nitrogen (measured value) in the water to be treated based on the data measured by the nitrogen monitor 12, and proceeds to step S7.

In step S7, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen exceeds the target value. If it is determined that the measured value of the amount of ammoniacal nitrogen exceeds the target value (step S7: YES), the process proceeds to step S8, and if the measured value of the amount of ammoniacal nitrogen is less than the target value (step S7: YES). In NO), the process proceeds to step S9.

In step S8, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to increase the rotation speed of the impeller 22 and increase the amount of oxygen supplied to the water to be treated. In step S9, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to reduce the rotation speed of the impeller 22 and reduce the amount of oxygen supplied to the water to be treated. After executing the processes of steps S8 and S9, the process returns to step S2 again, and the aeration operation is continued.

The control panel 13 repeats the processes of steps S6 to S9 until it is determined in step S3 that the operating time has reached the aeration time. That is, in a state where the measured value of the amount of ammoniacal nitrogen exceeds the target value, the rotation speed of the impeller 22 is increased, and the amount of oxygen supplied is continuously increased. If the measured value of the amount of ammoniacal nitrogen falls below the target value, the rotation speed of the impeller 22 is reduced and the amount of oxygen supplied is also reduced.

When the operation time reaches the set aeration time in step S3 (step S3: NO), the process proceeds to step S4 to perform intermittent aeration operation. Here, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to lower the impeller 22 and submerge it in water, and lower the rotation speed to execute anoxic operation.

In the following step S5, the determination unit 15 determines whether or not the operation time is less than the set one cycle time. If it is determined that the operation time is less than one cycle time (step S5: YES), the process returns to step S4 and the intermittent aeration operation is continued. When the operation time reaches one cycle time (step S5: NO), the one cycle operation is ended, the process proceeds to step S1 again, the operation of the next cycle is started, and the aeration operation is started (step S2). ..

In such an aeration / stirring system, the amount of ammoniacal nitrogen in the water to be treated in the reaction vessel 2 is measured by the nitrogen monitor 12, and the control unit 16 is a vertical axis type mechanical aeration / stirring machine based on the measured amount of ammoniacal nitrogen. Control the operation of 11. As a result, the rotation speed of the impeller 22 can be controlled according to the load (contamination degree and flow rate) of the water to be treated flowing into the reaction tank 2, and the amount of oxygen supplied to the water to be treated can be increased or decreased. it can. When the amount of ammoniacal nitrogen is large and the load of the water to be treated is large, the amount of oxygen supplied can be increased to stabilize the water quality. On the other hand, when the amount of ammoniacal nitrogen is small and the load of the water to be treated is small, the supply of wasteful oxygen can be reduced, the rotation of the impeller 22 can be suppressed, and the energy consumption can be suppressed.

(Second Example)
FIG. 4 is a flowchart showing a control procedure of the aeration stirring system according to the second embodiment. The same description as in the first embodiment described above will be omitted. The difference between the second embodiment and the first embodiment is the processing after the execution of step S6 in the aeration operation. Further, in the second embodiment, operating conditions different from those in the first embodiment are set.

The operating condition setting unit 14 sets the lower limit value of the ammoniacal nitrogen amount and the upper limit value of the ammoniacal nitrogen amount as the target value of the ammoniacal nitrogen amount. Further, the operating condition setting unit 14 sets the maximum value of the oxygen supply amount (100% oxygen supply amount operation) and the minimum value of the oxygen supply amount during the aeration operation.

The control panel 13 of the aeration agitation system calculates the amount of ammoniacal nitrogen (measured value) in the water to be treated (step S6), and proceeds to step S11. In step S11, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is larger than the set lower limit value. If it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the lower limit value (step S11: YES), the process proceeds to step S12, and if the measured value of the amount of ammoniacal nitrogen is less than the lower limit value (step S11: NO). ), The process proceeds to step S13.

In step S13, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11, sets the rotation speed of the impeller 22 to the lower limit value of the impeller rotation speed, and executes the oxygen supply stop operation. After the process of step S13 is executed, the process returns to step S2 again and the aeration operation is continued.

In step S12, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is greater than the set upper limit value. When it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the upper limit value (step S12: YES), the process proceeds to step S15, and when it is determined that the measured value of the amount of ammoniacal nitrogen is less than the upper limit value (step S12: YES). In S12: NO), the process proceeds to step S14.

In step S15, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11, sets the rotation speed of the impeller 22 to the upper limit value of the impeller rotation speed, and executes the operation with 100% oxygen supply. As a result, the treatment in an aerobic state can be promoted by maximizing the amount of oxygen supplied to the water to be treated. After the process of step S15 is executed, the process returns to step S2 and the aeration operation is continued.

In step S14, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11, sets the rotation speed of the impeller 22 to a value half of the upper limit of the impeller rotation speed, and operates the oxygen supply amount 50. Execute. As a result, the treatment in an aerobic state can be performed with the oxygen supply amount to the water to be treated set to 50% of the maximum value. After the process of step S14 is executed, the process returns to step S2 and the aeration operation is continued.

In such an aeration stirring system, when the amount of ammoniacal nitrogen is larger than the set upper limit value in the aeration operation, the impeller 22 is rotated at the upper limit value of the impeller rotation speed (first rotation speed), and the amount of ammoniacal nitrogen is present. Is less than the set upper limit value and larger than the set lower limit value, the impeller 22 is rotated at 50% of the impeller rotation speed upper limit value (second rotation speed), and the amount of ammonia nitrogen is set to the lower limit value. If it is less than, the impeller 22 can be rotated at the lower limit of the impeller rotation speed (third rotation speed). Thereby, the oxygen supply amount can be controlled by switching the oxygen supply amount in three stages according to the amount of ammoniacal nitrogen in the water to be treated. As a result, it is possible to control the operation in response to the load fluctuation of the inflowing water to be treated, stabilize the water quality of the treated water, and save energy.

(Third Example)
FIG. 5 is a flowchart showing a control procedure of the aeration stirring system according to the third embodiment. The same description as in the first embodiment described above will be omitted. The difference between the third embodiment and the first embodiment is the processing after the execution of step S6 in the aeration operation. Further, in the third embodiment, operating conditions different from those in the first embodiment are set.

The operating condition setting unit 14 sets the lower limit of the amount of ammoniacal nitrogen as the target value of the amount of ammoniacal nitrogen. Further, the operating condition setting unit 14 sets the maximum aeration time in one cycle.

The control panel 13 of the aeration agitation system calculates the amount of ammoniacal nitrogen (measured value) in the water to be treated (step S6), and proceeds to step S11. In step S11, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is larger than the set lower limit value. When it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the lower limit value (step S11: YES), the aeration operation is continued by returning to step S2, and the measured value of the amount of ammoniacal nitrogen is less than the lower limit value. (Step S11: NO), the process proceeds to step S16.

The control panel 13 determines whether or not the operating time is less than the maximum aeration time during the aeration operation (step S3). If the operation time is less than the maximum aeration time and the measured value of the amount of ammoniacal nitrogen is larger than the set lower limit value, the processes of steps S2, S3, S6, and S11 are repeated, and the aeration operation is continued. ..

If it is determined that the operation time has reached the aeration time (step S3: NO) and the measured value of the amount of ammoniacal nitrogen is smaller than the lower limit (step S11: NO), the process proceeds to step S16 and the aeration operation is completed. And perform anoxic operation. Here, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to lower the impeller 22 and lower the rotation speed of the impeller 22. As a result, an anaerobic state is formed in the reaction vessel 2.

After step S16, the process proceeds to step S5 to determine whether or not the operation time is less than one cycle time, and determine whether or not the operation time has reached one cycle time. If the operation time has not reached one cycle time (step S5: YES), the oxygen-free operation is continued. When the operation time reaches one cycle time (step S5: NO), the anoxic operation is ended, the operation of one cycle is ended, the process returns to step S1 again, and the operation of the next cycle is started. The impeller 22 is raised to the vicinity of the water surface, the rotation speed of the impeller 22 is increased, and the aeration operation is started (step S2).

In such an aeration stirring system, the aeration operation is continued when the amount of ammoniacal nitrogen is larger than the lower limit value during the aeration operation, and the aeration operation is terminated when the amount of ammoniacal nitrogen is smaller than the lower limit value, and the aeration operation is started. You can switch. As a result, when the amount of ammonia nitrogen falls below the lower limit value, the operation is switched to anoxic operation before the set maximum aeration time elapses, so that wasteful oxygen supply can be suppressed and energy can be saved.

(Fourth Example)
FIG. 6 is a flowchart showing a control procedure of the aeration agitation system according to the fourth embodiment. The same description as in the first embodiment described above will be omitted. The difference between the fourth embodiment and the first embodiment is the processing after the execution of step S6 in the aeration operation. Further, in the fourth embodiment, operating conditions different from those in the first embodiment are set. In the fourth embodiment, the amount of oxygen supplied can be changed based on the amount of ammoniacal nitrogen (NH _4- N) and the amount of nitrate nitrogen (NO _3- N).

The operating condition setting unit 14 sets the lower limit of the amount of ammoniacal nitrogen and the upper limit of the amount of ammoniacal nitrogen as the target value of the amount of ammoniacal nitrogen, and sets the target value of the amount of nitrate nitrogen as the target value of the amount of nitrate nitrogen. Set the upper limit.

The control panel 13 of the aeration agitation system calculates the amount of ammoniacal nitrogen (measured value) and the amount of nitrate nitrogen (measured value) in the water to be treated (step S6), and proceeds to step S21. In step S21, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is larger than the set upper limit value. If it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the upper limit value (step S21: YES), the process proceeds to step S24, and if the measured value of the amount of ammoniacal nitrogen is less than the upper limit value (step S21: NO). ), The process proceeds to step S22.

In step S24, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to increase the rotation speed of the impeller 22. After the process of step S24 is executed, the process returns to step S2 and the aeration operation is continued.

In step S22, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is larger than the set lower limit value. When it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the lower limit value (step S22: YES), the process proceeds to step S23, and when it is determined that the measured value of the amount of ammoniacal nitrogen is less than the lower limit value. (Step S22: NO), the process proceeds to step S25.

In step S23, the determination unit 15 determines whether or not the measured value of the nitrate nitrogen amount is larger than the set upper limit value. If it is determined that the measured value of the nitrate nitrogen amount is larger than the upper limit value (step S23: YES), the process proceeds to step S25, and if the measured value of the nitrate nitrogen amount is less than the upper limit value (step S23: In NO), the process returns to step S2 and the aeration operation is continued without changing the rotation speed of the impeller 22.

In step S25, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to reduce the rotation speed of the impeller 22. After the process of step S25 is executed, the process returns to step S2 and the aeration operation is continued.

FIG. 7 is a table showing the operating state of the aeration stirring system according to the fourth embodiment during the aeration operation, and shows the increase / decrease in the oxygen supply amount according to the amount of ammoniacal nitrogen and the amount of nitrate nitrogen. When the amount of ammoniacal nitrogen is larger than the upper limit value, the rotation speed of the impeller 22 is increased and the amount of oxygen supply is increased regardless of the amount of nitrate nitrogen. When the amount of ammoniacal nitrogen is less than the lower limit, the rotation speed of the impeller 22 is reduced and the amount of oxygen supply is reduced regardless of the amount of nitrate nitrogen.

When the amount of ammoniacal nitrogen is less than the upper limit value and larger than the lower limit value, and when the amount of nitrate nitrogen is larger than the upper limit value, the rotation speed of the impeller 22 is reduced and the oxygen supply amount is reduced. ..

When the amount of ammoniacal nitrogen was less than the upper limit value and larger than the lower limit value, and when the amount of nitrate nitrogen was less than the upper limit value, the rotation speed of the impeller 22 was not changed and the oxygen supply amount was maintained. The aeration operation is continued as it is.

In such an aeration stirring system, the amount of ammoniacal nitrogen and the amount of nitrate nitrogen are measured, and when the amount of ammoniacal nitrogen is larger than the set upper limit value (first determination threshold value) in the aeration operation, the impeller 22 The rotation speed can be increased, and the rotation speed of the impeller 22 can be decreased when the amount of ammoniacal nitrogen is less than the upper limit value and the amount of nitrate nitrogen is larger than the set upper limit value (second determination threshold value). .. As a result, when the amount of ammoniacal nitrogen is larger than the upper limit value, the amount of oxygen supply can be increased to promote nitrification. When nitrification of ammonia is promoted, ammonia in the water to be treated decreases and nitric acid increases. When the amount of ammoniacal nitrogen is less than the upper limit value and the amount of nitrate nitrogen is more than the upper limit value, the aeration and agitation system can reduce the rotation speed of the impeller to reduce the oxygen supply amount. As the amount of ammonia in the treated water decreases and the amount of nitric acid increases, the amount of oxygen supplied can be reduced to promote denitrification, and nitric acid can be converted to nitrogen gas. As a result, in the aeration stirring system, it is possible to control the operation according to the amount of ammoniacal nitrogen in the water to be treated to stabilize the water quality of the treated water and save energy.

(Fifth Embodiment)
FIG. 8 is a flowchart showing a control procedure of the aeration stirring system according to the fifth embodiment. The same description as in the first and fourth embodiments described above will be omitted. The difference between the fifth embodiment and the fourth embodiment is the processing after executing steps S21 to S23 in the aeration operation.

The operation condition setting unit 14 sets the rotation speed of the impeller 22 during the aeration operation in three stages of high-speed operation, medium-speed operation, and low-speed operation. The rotation speed of the impeller 22 in high-speed operation, medium-speed operation, and low-speed operation can be set based on, for example, past operation data and test results. The amount of oxygen supplied in high-speed operation is larger than the amount of oxygen supplied in medium-speed operation, and the amount of oxygen supplied in medium-speed operation is larger than the amount of oxygen supplied in low-speed operation.

When the control panel 13 of the aeration stirring system determines that the measured value of the amount of ammoniacal nitrogen is larger than the upper limit value (step S21: YES), the process proceeds to step S27, and the measured value of the amount of ammoniacal nitrogen is the upper limit value. If it is less than (step S21: NO), the process proceeds to step S22.

In step S27, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to operate the impeller 22 at high speed. After the process of step S27 is executed, the process returns to step S2 and the aeration operation is continued.

In step S22, the determination unit 15 determines whether or not the measured value of the amount of ammoniacal nitrogen is larger than the set lower limit value. When it is determined that the measured value of the amount of ammoniacal nitrogen is larger than the lower limit value (step S22: YES), the process proceeds to step S23, and when it is determined that the measured value of the amount of ammoniacal nitrogen is less than the lower limit value. (Step S22: NO), the process proceeds to step S29.

In step S23, the determination unit 15 determines whether or not the measured value of the nitrate nitrogen amount is larger than the set upper limit value. If it is determined that the measured value of the nitrate nitrogen amount is larger than the upper limit value (step S23: YES), the process proceeds to step S29, and if the measured value of the nitrate nitrogen amount is less than the upper limit value (step S23: In NO), the process proceeds to step S28.

In step S28, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to operate the impeller 22 at a medium speed. In step S29, the control unit 16 transmits a control signal to the vertical axis type mechanical aeration stirrer 11 to operate the impeller 22 at a low speed. After the processes of steps S28 and S29 are executed, the process returns to step S2 and the aeration operation is continued.

FIG. 9 is a table showing the operating status of the aeration stirring system according to the fifth embodiment during the aeration operation, and shows the operating status of the impeller according to the amount of ammoniacal nitrogen and the amount of nitrate nitrogen. When the amount of ammoniacal nitrogen is larger than the upper limit value, the impeller 22 is operated at high speed and the oxygen supply amount is set to be large regardless of the amount of nitrate nitrogen. When the amount of ammoniacal nitrogen is less than the lower limit, the impeller 22 is operated at a low speed regardless of the amount of nitrate nitrogen, and the oxygen supply amount is set to be small.

When the amount of ammoniacal nitrogen is less than the upper limit value and larger than the lower limit value, and when the amount of nitrate nitrogen is larger than the upper limit value, the impeller 22 is operated at a low speed and the oxygen supply amount is set to be small. To.

When the amount of ammoniacal nitrogen is less than the upper limit value and larger than the lower limit value, and the amount of nitrate nitrogen is less than the upper limit value, the impeller 22 is operated at medium speed and the oxygen supply amount becomes medium. Is set.

Also in the aeration / stirring system according to the fifth embodiment, the operation of the vertical axis type mechanical aeration / stirring machine 11 is controlled according to the load of the water to be treated to stabilize the water quality and suppress unnecessary oxygen supply. It is possible to reduce energy.

The present invention is not limited to the above-described embodiment, and various modifications as described below are possible without departing from the gist of the present invention.

In the above embodiment, for example, the speed of the impeller 22 is set to three stages of high-speed operation, medium-speed operation, and low-speed operation, but the speed may be set to four or more stages. Further, in the above embodiment, the oxygen supply amount is changed by changing the speed of the impeller 22, but the oxygen supply amount is changed by changing the number of the vertical axis type mechanical aeration stirrer 11 to be operated. It may be. For example, when increasing the oxygen supply amount, two vertical axis type mechanical aeration stirrers 11 are operated, and when decreasing the oxygen supply amount, one vertical axis type mechanical aeration stirrer 11 is operated. You may.

Further, the vertical axis type mechanical aeration stirrer 11 may be arranged at any position in the reaction tank 2. For example, as shown in FIG. 10, the present invention may be applied to an oxidation ditch 1B provided with a vertical axis type mechanical aeration stirrer 11 at the longitudinal end of the reaction vessel 2.

1,1B ... Oxidation ditch, 2 ... Reaction tank, 11 ... Vertical axis type mechanical aeration stirrer, 12 ... Nitrogen monitor (measuring unit), 16 ... Control unit, 22 ... Impeller.

Claims (7)

An aeration agitation system that repeats aeration operation, anaerobic operation, or shutdown.
A measuring unit that measures the amount of nitrogen in the water to be treated in a reaction vessel that nitrifies or denitrifies the water to be treated.
A control unit that controls the operation of the impeller that aerates and agitates the water to be treated based on the amount of nitrogen measured by the measuring unit is provided.
The measuring unit measures the amount of ammoniacal nitrogen as the amount of nitrogen, and then
In the aeration operation, when the amount of ammoniacal nitrogen is larger than the upper limit of the target value, the control unit sets the rotation speed of the impeller to high-speed operation, and the amount of ammoniacal nitrogen is less than the lower limit of the target value. In some cases, an aeration and agitation system characterized in that the rotation speed of the impeller is set to low speed operation . An aeration agitation system that repeats aeration operation, anaerobic operation, or shutdown.
A measuring unit that measures the amount of nitrogen in the water to be treated in a reaction vessel that nitrifies or denitrifies the water to be treated.
A control unit that controls the operation of the impeller that aerates and agitates the water to be treated based on the amount of nitrogen measured by the measuring unit is provided.
The measuring unit measures the amount of ammoniacal nitrogen as the amount of nitrogen, and then
In the aeration operation, when the amount of ammoniacal nitrogen is equal to or higher than the first determination threshold value, the control unit increases the number of rotations of the impeller to a preset value, and the amount of ammoniacal nitrogen is said to be the same. An aeration stirring system characterized in that the rotation speed of the impeller is reduced to a preset value when the value is less than the first determination threshold value. The measuring unit measures the amount of nitrate nitrogen and
The rotation speed of the impeller is the upper limit of the amount of ammoniacal nitrogen in the water to be treated, the lower limit of the amount of ammoniacal nitrogen, the upper limit of the amount of nitrate nitrogen, and the lower limit of the amount of nitrate nitrogen of the impeller . The aeration and agitation system according to claim 1, wherein the rotation speed is a predetermined value. The aeration / stirring system according to any one of claims 1 to 3, further comprising a storage unit for storing information on operating conditions or measured values measured by the measuring unit. A reaction tank that nitrifies or denitrifies the water to be treated, or a reaction tank that has a non-terminal circulation channel that nitrifies or denitrifies the water to be treated .
A water treatment facility comprising the aeration agitation system according to any one of claims 1 to 4 . A control method for an aeration agitation system that repeats aeration operation, anaerobic operation, or shutdown.
A measurement step for measuring the amount of nitrogen in the water to be treated in a reaction vessel for nitrifying or denitrifying the water to be treated, and
A control step for controlling the operation of the impeller that aerates and agitates the water to be treated based on the amount of nitrogen measured in the measurement step is provided.
In the measurement step, the amount of ammoniacal nitrogen is measured as the amount of nitrogen.
In the control step, when the amount of ammoniacal nitrogen is larger than the upper limit of the target value in the aeration operation, the rotation speed of the impeller is set to high speed operation, and the amount of ammoniacal nitrogen is less than the lower limit of the target value. A method for controlling an aeration and agitation system , which comprises operating the impeller at a low speed . A control method for an aeration agitation system that repeats aeration operation, anaerobic operation, or shutdown.
A measurement step for measuring the amount of nitrogen in the water to be treated in a reaction vessel for nitrifying or denitrifying the water to be treated, and
A control step for controlling the operation of the impeller that aerates and agitates the water to be treated based on the amount of nitrogen measured in the measurement step is provided.
In the measurement step, the amount of ammoniacal nitrogen is measured as the amount of nitrogen.
In the control step, when the amount of ammoniacal nitrogen is equal to or higher than the first determination threshold value in the aeration operation, the number of rotations of the impeller is increased to a preset value, and the amount of ammoniacal nitrogen is said to be said. A control method for an aeration / stirring system, which comprises reducing the rotation speed of the impeller to a preset value when the value is less than the first determination threshold value.

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