JP7023609B2 - Sewage treatment equipment - Google Patents

Description

The present application relates to a sewage treatment apparatus.

In the sewage treatment apparatus described in Patent Document 1, by supplying air to the sewage, the decomposition of organic matter using microorganisms is promoted and the sewage is purified. The operation of the stirring device that circulates the sewage in the sewage tank is controlled based on the dissolved oxygen amount of the sewage.

Japanese Unexamined Patent Publication No. 2008-36517

The present application provides a sewage treatment device capable of reducing power consumption.

The sewage treatment device includes a stirring device (3) for adjusting the stirring flow rate of the sewage, an aeration blower (4) for supplying air to the sewage, and a blower device (4) after the air is supplied. A first oxygen amount detector (5A) that detects the amount of oxygen dissolved in sewage, and a second oxygen amount detector (5B) that detects the amount of oxygen dissolved in sewage before air is supplied by the blower (4). ) And the control device (7) that controls the operation of the stirring device (3), the first detection amount (DO1) and the second oxygen amount detector (5B) detected by the first oxygen amount detector (5A). ) Is provided with a control device (7) that changes or maintains the stirring flow rate by using a control parameter based on the difference from the second detection amount (DO2) detected.

Aerobic microorganisms consume oxygen as they break down organic matter. That is, it is sufficient for the sewage treatment device to supply the amount of oxygen required for the microorganism to decompose the organic matter (hereinafter referred to as the required oxygen amount). In other words, supplying oxygen in excess of the amount required by microorganisms does not contribute to the purification of sewage, and power is wasted in the sewage treatment device.

On the other hand, in the present application, the difference between the first detection amount (DO1) detected by the first oxygen amount detector (5A) and the second detection amount (DO2) detected by the second oxygen amount detector (5B). Since the stirring flow rate of the sewage is changed or maintained by using the control parameter based on the above, it is possible to reduce the power consumption of the stirring device (3) and the blowing device (4).

That is, since the control parameter is a value based on the difference between the first detected amount (DO1) and the second detected amount (DO2), if the control parameter is within a predetermined range, the air satisfying the required oxygen amount is sewage. It can be considered to be supplied to the microorganisms inside.

By agitating the sewage by the agitator (3), the air supplied to the sewage by the blower (4), that is, oxygen, can be supplied to all the microorganisms in the sewage tank (2). Therefore, it is possible to supply the required amount of oxygen to all the microorganisms in the sewage tank (2) without increasing the amount of air blown by the blower device (4). Further, if the stirring flow rate is controlled by using the control parameter, it is possible to reduce the power consumption of the stirring device (3) and the blowing device (4).

Incidentally, the reference numeral in each of the parentheses is an example showing a correspondence relationship with the specific configuration and the like described in the embodiment described later, and the present invention is limited to the specific configuration and the like shown in the reference numeral in the parentheses. It's not something.

It is explanatory drawing of the sewage treatment apparatus 1 which concerns on 1st Embodiment of this invention. It is an operation flowchart of the sewage treatment apparatus 1 which concerns on 1st Embodiment of this invention. It is an operation flowchart of the sewage treatment apparatus 1 which concerns on 1st Embodiment of this invention. It is explanatory drawing of the sewage treatment apparatus 1 which concerns on 2nd Embodiment of this invention. It is explanatory drawing of the sewage treatment apparatus 1 which concerns on 3rd Embodiment of this invention.

The "embodiment of the invention" described below is an example of an embodiment belonging to the technical scope of the present invention. That is, the matters specifying the invention described in the claims are not limited to the specific configuration, structure, etc. shown in the following embodiments.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the arrows and the like indicating the directions attached to each figure are described in order to make it easier to understand the relationship between each figure. The present invention is not limited to the directions attached to each figure.

At least one member or part described with a reference numeral is provided, except when a notice such as "one" is given. That is, if there is no notice such as "one", two or more of the members may be provided.

(First Embodiment)
In this embodiment, as shown in FIG. 1, the present invention is applied to an oxidation ditch type sewage treatment device 1.

1. 1. Overview of sewage treatment equipment (see Fig. 1)
The sewage treatment device 1 includes at least a sewage tank 2, a stirrer 3, a blower 4, a first oxygen amount detector 5A, a second oxygen amount detector 5B, and the like. Sewage to be treated flows into the sewage tank 2. The sewage tank 2 constitutes a substantially elliptical or oval water channel 2A. The sewage circulates in the water channel 2A. In the sewage tank 2 shown in FIG. 1, sewage circulates counterclockwise.

The stirring device 3 stirs the sewage in the sewage tank 2 and adjusts the stirring flow rate of the sewage. In this embodiment, a plurality of stirring devices 3 are provided. Each stirring device 3 includes an axial fan-shaped propeller 3A, a driving inverter 3B, and the like.

The propeller 3A circulates the sewage by rotating in the sewage tank 2 so as to stir the sewage. That is, in the present embodiment, the sewage is agitated by circulating the sewage. Therefore, the stirring flow rate according to the present embodiment substantially coincides with the circulation flow rate.

Drive inverter 3B (referred to as propeller inverter 3B). Drives an electric motor (not shown) that rotates the propeller 3A. The propeller inverter 3B continuously changes the rotation speed of the propeller 3A, that is, the stirring flow rate by continuously changing the drive current frequency within a predetermined range.

The blower 4 supplies air for aeration to the sewage in the sewage tank 2. The blower 4 includes a blower 4A, an air diffuser 4B, and the like. The blower 4A sucks the air in the atmosphere and blows it to the sewage tank 2. The air diffuser 4B atomizes the air blown by the blower 4A and promotes the dissolution of oxygen into the sewage.

The drive inverter 4C (hereinafter referred to as a blower inverter 4C) drives an electric motor (not shown) that rotates the blower 4A. The blower inverter 4C continuously changes the drive current frequency within a predetermined range to continuously change the rotation speed of the blower 4A, that is, the amount of supply air supplied to the sewage.

The first oxygen amount detector 5A detects the amount of oxygen dissolved in the sewage after the air is supplied by the blower 4. The second oxygen amount detector 5B detects the amount of oxygen dissolved in the sewage before the air is supplied by the blower 4.

In the sewage tank 2 according to the present embodiment, sewage circulates in the water channel 2A. Therefore, the first oxygen amount detector 5A detects the dissolved oxygen amount in the zone where air (oxygen) is supplied by the blower 4 in the water channel 2A, that is, on the downstream side of the sewage flow from the air diffuser 4B.

The second oxygen amount detector 5B detects the dissolved oxygen amount on the upstream side of the sewage flow from the air diffuser 4B. A water quality analyzer 6 is provided on the downstream side of the sewage flow from the air diffuser 4B. The water quality analyzer 6 detects the concentration of a predetermined substance contained in the sewage.

The "substance" is a substance such as ammonia nitrogen that forms a parameter indicating the "degree of water contamination". The higher the concentration of ammonia nitrogen, the more polluted the water, that is, the polluted water.

The control device 7 controls the operation of the stirring device 3 and the blower device 4. The control device 7 changes or maintains the stirring flow rate and the supply air amount by using the control parameter ΔDO. The control parameter ΔDO is a value based on the difference between the first detection amount DO1 detected by the first oxygen amount detector 5A and the second detection amount DO2 detected by the second oxygen amount detector 5B.

The control parameter ΔDO according to the present embodiment is an absolute value of the difference between the first detected amount DO1 and the second detected amount DO2 (= | first detected amount DO1-second detected amount DO2 |).
The control device 7 is composed of a computer having a CPU, a ROM, a RAM, and the like. Software (program) for controlling the operation of the stirring device 3 and the blowing device 4 is stored in advance in a non-volatile storage unit (not shown) such as a ROM.

2. 2. Control of sewage treatment device 2.1 Outline of control Input the concentration detected by the water quality analyzer 6 (hereinafter referred to as the detection concentration NH4-N), the first detection amount DO1 and the second detection amount DO2 to the control device 7. Has been done.

When the detected concentration NH4-N exceeds a predetermined target concentration, the control device 7 increases at least one of the stirring flow rate and the supply air amount to activate the decomposition action of the microorganism.

When the stirring flow rate is increased, the air supplied to the sewage, that is, oxygen can be supplied to all the microorganisms in the sewage tank 2. That is, when the stirring flow rate is increased, the non-uniformity of the dissolved oxygen amount is alleviated and the substantial amount of oxygen supplied to the microorganism is increased, so that the decomposition action can be activated.

When the second detection amount DO2 is larger than the predetermined target second detection amount DO2, the control device 7 reduces at least one of the stirring flow rate and the supply air amount. This is because there is a high possibility that the amount of oxygen required by microorganisms to decompose organic matter, that is, oxygen (air) exceeding the required amount of oxygen, is supplied to the sewage.

When the second detection amount DO2 is smaller than the predetermined target second detection amount DO2, the control device 7 increases or decreases at least one of the stirring flow rate and the supply air amount based on the control parameter ΔDO.

Specifically, when the control parameter ΔDO is equal to or greater than a predetermined target dissolved oxygen difference (hereinafter referred to as target ΔDO), it is highly possible that oxygen exceeding the required oxygen amount is supplied to the sewage. In that case, the control device 7 reduces at least one of the stirring flow rate and the amount of supplied air.

When the control parameter ΔDO is smaller than the target ΔDO, it is highly possible that the required amount of oxygen is not supplied to the sewage. In that case, the control device 7 increases at least one of the stirring flow rate and the amount of supplied air.

When at least one of the stirring flow rate and the supply air amount is changed, the control device 7 stops the process until a predetermined time elapses after the change. After that, the control device 7 executes the next control process when the time has elapsed.

The control device 7 determines at least one of the stirring flow rate and the supply air amount when the control parameter ΔDO is out of the predetermined range, that is, the state in which the control parameter ΔDO is larger than the target ΔDO continues for a predetermined predetermined time. change. The time for suppressing the influence of the instantaneous value in this way is called the judgment waiting time.

2.2 Details of control (see FIGS. 2 and 3)
When the start switch (not shown) of the sewage treatment device 1 is turned on, the control device 7 reads the software for executing the control shown in FIGS. 2 and 3 from the non-volatile storage unit and executes the control. do.

When the software is activated, the control device 7 determines whether or not the detected concentration NH4-N is equal to or less than a predetermined target concentration (S1). When the control device 7 determines that the detected concentration NH4-N is larger than the predetermined target concentration (S1: NO), the control device 7 executes S27.

When the control device 7 determines that the detected concentration NH4-N is equal to or lower than the predetermined target concentration (S1: YES), the control device 7 determines whether or not the second detected amount DO2 is larger than the target DO2 (S3). ).

When the control device 7 determines that the second detection amount DO2 is larger than the target DO2 (S3: YES), the drive current frequency (hereinafter referred to as the blower frequency) currently output by the blower inverter 4C is set in advance. It is determined whether or not the frequency is the lower limit (minimum) frequency in the determined range (S5).

When the control device 7 determines that the blower frequency is the minimum frequency (S5: YES), the number of the stirring devices 3 (propeller 3A) currently in operation is the minimum number (one in the present embodiment). ) (S7).

When the control device 7 determines that the number of stirring devices 3 is not the minimum number (in the present embodiment, the number of operating devices 3 is currently two) (S7: NO), at least one stirring device 3 is used. (Propeller 3A) is stopped (S23).

After stopping at least one stirring device 3 (S23), the control device 7 executes S1 again when a predetermined time (hereinafter, referred to as an effect waiting time) has elapsed (S25).

When the control device 7 determines that the number of the stirring devices 3 is the minimum number (S7: YES), the drive current frequency (hereinafter referred to as the propeller frequency) currently output by the propeller inverter 3B is set in advance. It is determined whether or not the frequency is the lower limit (minimum) of the determined range (S9).

When the control device 7 determines that the propeller frequency is not the minimum frequency (S9: NO), the control device 7 lowers the propeller frequency to reduce the stirring flow rate (S11). After reducing the stirring flow rate (S11), the control device 7 executes S1 again when the effect waiting time has elapsed (S13). When the control device 7 determines that the propeller frequency is the minimum frequency (S9: YES), the control device 7 stops the stirring device 3 driven at the minimum frequency, and then executes S1 again.

When the control device 7 determines that the blower frequency is not the minimum frequency (S5: NO), the control device 7 lowers the blower frequency to reduce the supply air amount (S19). After reducing the supply air amount (S19), the control device 7 executes S1 again when the effect waiting time has elapsed (S21).

When the control device 7 determines that the second detection amount DO2 is not larger than the target DO2 (S3: NO), after calculating the control parameter ΔDO (S15), whether or not the control parameter ΔDO is larger than the target ΔDO. Is determined (S17).

When the control device 7 determines that the control parameter ΔDO is not larger than the target ΔDO (S17: NO), the control device 7 executes S5. When the control device 7 determines that the control parameter ΔDO is larger than the target ΔDO (S17: YES), the maximum number of stirring devices 3 (propeller 3A) currently in operation is the maximum number (2 in the present embodiment). It is determined whether or not it is a stand) (S27).

When the control device 7 determines that the number of stirring devices 3 (propeller 3A) currently in operation is not the maximum number (S27: NO), the current propeller frequency is the upper limit (maximum) in a predetermined range. ) It is determined whether or not it is a frequency (S29).

When the control device 7 determines that the current propeller frequency is not the maximum frequency (S29: NO), the control device 7 increases the propeller frequency to increase the stirring flow rate (S31). The control device 7 executes S1 again when the effect waiting time elapses (S33) after increasing the stirring flow rate (S31).

When the control device 7 determines that the current propeller frequency is the maximum frequency (S29: YES), the control device 7 operates the stopped stirring device 3 at the minimum wave number to increase the stirring flow rate (S41). The control device 7 executes S1 again when the effect waiting time has elapsed (S43) after increasing the stirring flow rate (S41).

When the control device 7 determines that the number of the stirring devices 3 (propeller 3A) currently in operation is the maximum number (S27: YES), whether or not the current blower frequency is the maximum frequency is determined. Judgment (S35).

When the control device 7 determines that the current blower frequency is not the maximum frequency (S35: NO), the control device 7 increases the blower frequency to increase the supply air amount (S37). After increasing the supply air amount (S37), the control device 7 executes S1 again when the effect waiting time has elapsed (S39). When the control device 7 determines that the current blower frequency is the maximum frequency (S35: YES), the control device 7 executes S1 again.

3. 3. Features of the sewage treatment device according to this embodiment Oxygen is consumed when microorganisms decompose organic matter. That is, it is sufficient for the sewage treatment device 1 to supply the required amount of oxygen. In other words, supplying oxygen in excess of the amount required by the microorganism does not contribute to the purification of sewage, and the sewage treatment device 1 wastes power.

On the other hand, in the present embodiment, at least one of the stirring flow rate and the supply air amount of the sewage is changed or maintained by using the control parameter ΔDO, so that the power consumption of the stirring device 3 and the blowing device 4 is reduced. Is possible.

That is, since the control parameter ΔDO is a value based on the difference between the first detection amount DO1 and the second detection amount DO2, if the control parameter ΔDO is within a predetermined range, the air satisfying the required oxygen amount is in the sewage. It can be considered to be supplied to microorganisms.

Then, when the stirring device 3 stirs the sewage, the air supplied to the sewage by the blower device 4, that is, oxygen, can be supplied to all the microorganisms in the sewage tank 2. Therefore, it is possible to supply the required amount of oxygen to all the microorganisms in the sewage tank 2 without increasing the amount of air blown by the blower device 4. Further, if the stirring flow rate is controlled by using the control parameter ΔDO, it is possible to reduce the power consumption of the stirring device 3 and the blowing device 4.

The control device 7 changes or maintains at least one of the stirring flow rate and the supply air amount so that the detected concentration NH4-N becomes equal to or less than the target concentration. As a result, sewage can be purified while reducing the power consumption of the stirring device 3 and the blowing device 4.

When the detected concentration NH4-N is larger than the target concentration, the control device 7 executes an ascending process in which at least one of the stirring flow velocity and the supply air amount is made larger than the current one. As a result, sewage can be reliably purified.

When the detected concentration NH4-N is smaller than the target concentration, the control device 7 executes a reduction process of reducing at least one of the stirring flow rate and the supply air amount to the current level. As a result, sewage can be purified while reducing the power consumption of the stirring device 3 and the blowing device 4.

The control device 7 executes the next process when the effect waiting time elapses after changing at least one of the stirring flow rate and the supply air amount. As a result, it is possible to prevent the stirring flow rate and the amount of supplied air from being changed more than necessary. As a result, the sewage can be purified while reducing the power consumption of the stirring device 3 and the blowing device 4.

The control device 7 changes at least one of the stirring flow rate and the supply air amount when the state in which the control parameter ΔDO is larger than the target ΔDO continues for a predetermined predetermined time (for example, the determination waiting time). Sewage can be purified while reducing the power consumption of the agitator 3 and the blower 4.

That is, the state in which the control parameter ΔDO is larger than the target ΔDO is “a state in which oxygen is consumed more than the target by microorganisms, but an oxygen is excessive due to an excessive oxygen supply” or “a state in which oxygen is insufficient in an oxygen supply”. .. In such a state, excess power consumption may be generated due to excessive oxygen supply, or the decomposition action of microorganisms may become inactive due to insufficient supply.

Therefore, when the control parameter ΔDO is larger than the target ΔDO, the control device 7 changes at least one of the stirring flow rate and the supply air amount when the time corresponding to the determination waiting time continues.

Since the control device 7 according to the present embodiment executes S1 and the like after the effect waiting time has elapsed in S33, S43, and S39, substantially "a state in which the control parameter ΔDO is larger than the target ΔDO is determined in advance. After the predetermined time continues, at least one of the stirring flow rate and the amount of supplied air will be changed. "

(Second Embodiment)
In the above-described embodiment, the change range when increasing or decreasing at least one of the propeller frequency and the blower frequency was constant. On the other hand, the change width is changed by using the temperature of sewage.

That is, the sewage treatment device 1 according to the present embodiment has a temperature detector 8 for detecting the temperature of the sewage, as shown in FIG. The temperature detector 8 detects the temperature of the sewage before the air is supplied by the blower 4.

The control device 7 determines a change width based on the detection temperature of the temperature detector 8 before increasing or decreasing at least one of the propeller frequency and the blower frequency, and uses the determined change width to determine the frequency. To change.

The control device 7 according to the present embodiment reads the detection temperature of the temperature detector 8 and determines the change width before executing S1. The relationship between the sewage temperature and the change width is stored in advance in the non-volatile storage unit such as the ROM of the control device 7.

Since the same configuration requirements and the like as those in the above-described embodiment are designated by the same reference numerals as those in the above-described embodiment, duplicate description will be omitted.
As described above, in the present embodiment, sewage can be purified while reducing the power consumption of the stirring device 3 and the blowing device 4.

That is, (1) when the sewage temperature is high, the decomposition action of microorganisms is activated and the saturated dissolved oxygen amount decreases. (2) When the sewage temperature is low , the decomposition action of microorganisms decreases and the saturated dissolved oxygen amount increases.

Therefore, when the propeller frequency is increased when the sewage temperature is high, the control device 7 changes with a large change range. As a result, it can be expected that the microorganisms will circulate quickly and enter an aerobic state to promote the decomposition and nitrate of organic matter by the microorganisms.

When the propeller frequency is reduced when the sewage temperature is high, the control device 7 changes with a small change range . This makes it possible to reduce the power consumption by lowering the propeller frequency while utilizing the activation of microorganisms.

When the propeller frequency is reduced when the sewage temperature is low, the control device 7 changes with a large change range. This allows the microorganisms to circulate slowly, ensuring that the microorganisms consume the dissolved oxygen.
When the propeller frequency is increased when the sewage temperature is low, the control device 7 changes with a small change range. This makes it possible to give the microorganism time to consume oxygen.

When the blower frequency is changed when the sewage temperature is high, the control device 7 changes with a small change range. This makes it possible to supply air according to the amount of oxygen dissolved in the sewage.
When the blower frequency is changed when the sewage temperature is low, the control device 7 changes with a large change range. As a result, the sewage containing a larger amount of dissolved oxygen circulates slowly, so that the operation suitable for "high saturated dissolved oxygen amount" and "situation of microorganisms with reduced decomposition action" becomes possible.

(Third Embodiment)
In S1 according to the above-described embodiment, it was determined whether or not the detected concentration NH4-N was less than a predetermined target concentration. On the other hand, in the present embodiment, in addition to the ammonia nitrogen, the pH sensor 9 (see FIG. 5) also detects the hydrogen ion index (pH value) of the sewage, and the detection value is also used to detect the stirring flow rate. And change or maintain at least one of the supplied air volumes.

That is, when the acidity is larger than the predetermined value, that is, when the pH value is smaller than the predetermined value, the control device 7 is when the detected concentration NH4-N is equal to or higher than the predetermined target concentration. Performs the same control as.

The control device 7 detects when the acidity is smaller than a predetermined value, that is, when the pH value is larger than the predetermined value and the detection concentration NH4-N is less than the predetermined target concentration. The same control as when the concentration NH4-N is less than a predetermined target concentration is performed.

Even if the detected concentration NH4-N is less than the predetermined target concentration, if the pH value is larger than the predetermined value, it is the same as when the detected concentration NH4-N is equal to or higher than the predetermined target concentration. Control.

Only when nitrification is progressing in the aerobic region where the pH value is high, at least one of the stirring flow rate and the amount of supplied air is increased so that the detected concentration NH4-N is equal to or higher than the predetermined target concentration. Activates the decomposition action. That is, other than this, it is possible to further appropriately reduce the power consumption by reducing at least one of the stirring flow rate and the amount of supplied air.

Since the same configuration requirements and the like as those in the above-described embodiment are designated by the same reference numerals as those in the above-described embodiment, duplicate description will be omitted.
(Fourth Embodiment)
This embodiment is an example in which an electric conductivity meter is used as the water quality analyzer 6. Since the electrical conductivity has a high correlation with nitrate nitrogen, it is an index of the activation of microorganisms in the aerobic region.

That is, in this embodiment, an index having a correlation with a general water quality index such as an ammonia nitrogen meter or a nitrate nitrogen meter is used. Therefore, for example, a “oxidation-reduction potential meter” that is an index of the degree of anaerobicity and the degree of aerobicity of microorganisms may also be used as the water quality analyzer 6.

If the larger the index that correlates with the water quality index, the smaller the general water quality index such as the ammonia nitrogen meter or nitrate nitrogen meter, the magnitude determination in S1 of FIG. 2, that is, "YES". And "NO" need to be in the opposite relationship.

(Other embodiments)
In the above-described embodiment, the present invention is applied to the oxidation ditch type sewage treatment device 1. However, the invention disclosed in the present specification is not limited to this. That is, for example, the sewage treatment device 1 may be of a type that switches between an aerobic state and an anaerobic state at predetermined time intervals.

In the above-described embodiment, the circulation flow velocity and the amount of supplied air are continuously changed by the propeller inverter 3B and the blower inverter 4C. However, the invention disclosed in the present specification is not limited to this. That is, for example, the circulation flow velocity and the supply air amount may be changed by intermittently controlling the operating time of the electric motor as in the PWM control.

In the above-described embodiment, a plurality of stirring devices 3 are provided. However, the invention disclosed in the present specification is not limited to this. That is, for example, the stirring flow rate may be changed by one stirring device 3.

In the above-described embodiment, the target second detection amount DO2, the target ΔDO, the target concentration, and the like (hereinafter referred to as the target value) are constant values. However, the invention disclosed in the present specification is not limited to this.

That is, for example, when comparing the target value and the detected value, the target value for determining "greater than the target value or greater than or equal to the target value" and "less than the target value or less than or equal to the target value" are determined. A predetermined hysteresis may be provided at the time of comparison determination by setting a value different from the target value at the time of comparison.

Furthermore, the present invention is not limited to the above-described embodiment as long as it conforms to the gist of the invention described in the claims. Therefore, at least two of the plurality of embodiments described above may be combined.

1 ... Sewage treatment equipment 2 ... Sewage tank 2A ... Waterway 3 ... Stirring device 3A ... Propeller 3B ... Drive inverter (propeller inverter)
4 ... Blower 4A ... Blower 4B ... Air diffuser 4C ... Drive inverter (blower inverter)
5A ... 1st oxygen amount detector 5B ... 2nd oxygen amount detector 6 ... Water quality analyzer 7 ... Control device 8 ... Temperature detector

Claims (7)

A stirring device for stirring the sewage in the sewage tank and adjusting the stirring flow rate of the sewage,
An aeration blower that supplies air to the sewage in the sewage tank,
A first oxygen amount detector that detects the amount of oxygen dissolved in the sewage after air is supplied by the blower, and
A second oxygen amount detector that detects the amount of oxygen dissolved in the sewage before air is supplied by the blower, and
A control device that controls the operation of the stirring device, and is a control parameter based on the difference between the first detection amount detected by the first oxygen amount detector and the second detection amount detected by the second oxygen amount detector. Equipped with a control device that changes or maintains the stirring flow rate using
The control device has a function of decreasing the stirring flow rate when the control parameter is equal to or more than a predetermined target dissolved oxygen difference, and increasing the stirring flow rate when the control parameter is smaller than the target dissolved oxygen difference. Sewage treatment equipment that can demonstrate . Equipped with a water quality analyzer that detects the concentration of predetermined substances contained in sewage,
The sewage treatment device according to claim 1, wherein the control device changes or maintains a stirring flow rate so that the concentration detected by the water quality analyzer is equal to or lower than a predetermined concentration. The sewage treatment device according to claim 2, wherein when the concentration detected by the water quality analyzer is larger than a predetermined concentration, the control device executes an ascending treatment for increasing the stirring flow rate from the present time. The sewage treatment device according to claim 2, wherein when the concentration detected by the water quality analyzer is smaller than a predetermined concentration, the control device executes a reduction treatment of reducing the stirring flow rate to the current level. The sewage treatment device according to any one of claims 1 to 4, wherein the control device executes the next treatment when a predetermined time has elapsed after changing the stirring flow rate. The sewage treatment according to any one of claims 1 to 5, wherein the control device changes the stirring flow rate when the state in which the control parameter is out of the predetermined range continues for a predetermined predetermined time. Device. A second control device for controlling the operation of the blower is provided.
The sewage treatment device according to any one of claims 1 to 5, wherein the second control device changes or maintains the amount of air supplied to the sewage by using the control parameters.

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