A fan system suitable for rural sewage SBR treatment and a control method thereof

Abstract

The application relates to a fan system suitable for rural sewage SBR treatment and a control method thereof, and relates to the technical field of sewage treatment. The control method comprises the following steps: S1, discharging sewage into SBR tanks, and sequentially entering the water inlet stage according to the time sequence; S2, after the sewage is discharged into the SBR tanks, sequentially entering the aeration stage according to the time sequence; S21, in the same time, at least two groups of SBR tanks in the SBR tanks are in the aeration stage; S22, starting one fan to aerate the corresponding SBR tank through the aeration pipeline, and the corresponding branch pipeline on the aeration pipeline aerates the SBR tank in mutual communication with the branch pipeline; S3, carrying out sedimentation on the SBR tank after aeration, and sequentially entering the sedimentation stage; S4, discharging sewage from the SBR tank; and S5, repeating the above steps S1-S4. The application can realize the aeration of multiple SBR tanks at the same time through one fan, an aeration pipeline and branch pipelines.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a fan system suitable for SBR treatment of rural sewage and a control method thereof. Background Art

[0002] SBR is the abbreviation of sequential batch activated sludge process, which is an activated sludge wastewater treatment technology that operates in an intermittent aeration mode, also known as sequencing batch activated sludge process.

[0003] SBR technology replaces spatial separation with time-segmented operation, replaces steady-state biochemical reactions with unstable biochemical reactions, and replaces traditional dynamic sedimentation with static ideal sedimentation. Its key features are orderly and intermittent operation. The core of SBR technology is the SBR reactor, which integrates homogenization, primary sedimentation, biodegradation, and secondary sedimentation into a single tank, without a sludge return system.

[0004] Currently, most SBR wastewater treatment systems operate in a cycle of inlet-reaction-sedimentation-effluent-idle mode. This operation is divided into different time sequences to achieve different functions. An SBR tank has only one aeration tank, and the operating cycle of the SBR process is T, which is generally an integer divisor of 24, such as 4 hours, 6 hours, 8 hours, 12 hours, or 24 hours.

[0005] Regarding the aforementioned technologies, SBRs typically utilize multiple alternating groups to maintain continuous water inflow. When necessary, water inflow and aeration processes occur simultaneously. This means that most SBRs require n fans corresponding to n groups of SBR tanks. Each group of SBR tanks requires a corresponding fan to be turned on during aeration to achieve precise aeration at each reaction stage. For smaller-scale treatment sites, power-frequency fans are generally used to save initial investment, which results in higher operating power consumption, increased equipment wear, and increased maintenance costs. Summary of the Invention

[0006] The purpose of this application is to provide a fan operation control method for small-scale sewage SBR treatment that saves energy and reduces consumption.

[0007] In the first aspect, the present application provides a fan system suitable for SBR treatment of rural sewage, which adopts the following technical solutions:

[0008] A fan system suitable for SBR treatment of rural sewage comprises a plurality of fans and a plurality of SBR tanks arranged in sequence, wherein the fans are arranged in one-to-one correspondence with the SBR tanks, and each fan is provided with a corresponding ventilation pipe, wherein both ends of the ventilation pipe are respectively connected with the air outlet of the fan and the interior of the corresponding SBR tank; each ventilation pipe is connected with a branch pipe, and the branch pipe is also connected with the adjacent ventilation pipes in sequence, and the branch pipe on the last ventilation pipe is connected with the first ventilation pipe; the branch pipes are each provided with a ball valve and a solenoid valve.

[0009] By adopting the above technical solution, a ventilation duct is provided between the fan and the SBR pool, so that the fan can pass air into the corresponding SBR pool to achieve aeration; branch ducts are provided between different ventilation ducts, so that one fan can blow air into different SBR pools through the ventilation duct and the branch duct, and a solenoid valve and a ball valve are provided on the branch duct. The solenoid valve can control the opening and closing of the branch duct, and the ball valve can change the ventilation volume of the branch duct, so that one fan can simultaneously pass air of different flow rates into multiple SBR pools, thereby greatly reducing the operating power consumption of multiple fans aerating multiple SBR pools at the same time.

[0010] Optionally, a plurality of aeration tubes are provided at the bottom of the SBR tank, a plurality of aeration holes are opened on the aeration tubes, and the aeration tubes are interconnected with the corresponding ventilation pipes.

[0011] By adopting the above technical solution and arranging the aeration pipe and the aeration holes on the aeration pipe, aeration can be carried out into the aeration pipe through the ventilation pipe, thereby realizing aeration of the SBR tank and completing the aeration treatment of the sewage.

[0012] Secondly, the present application provides a fan system control method suitable for SBR treatment of rural sewage, which adopts the following technical solutions:

[0013] A fan system control method suitable for SBR treatment of rural sewage includes the following steps:

[0014] S1: Sewage is discharged into the SBR tank, and several SBR tanks enter the water inflow stage in sequence;

[0015] S2: After sewage is discharged into the SBR tank, several of the SBR tanks enter the aeration stage in sequence;

[0016] S21: At the same time, at least two of the plurality of SBR tanks are in the aeration stage;

[0017] S22: starting one of the fans to ventilate the corresponding SBR tank through the ventilation pipe, and opening the corresponding branch pipe on the ventilation pipe to ventilate the SBR tank connected to the branch pipe;

[0018] S3: The aerated SBR tank is subjected to sedimentation, and several SBR tanks enter the sedimentation stage in sequence;

[0019] S4: Discharge sewage from the SBR tank after sedimentation;

[0020] S5: Each of the SBR tanks repeats the above S1-S4 in sequence.

[0021] By adopting the above technical solution, each group of SBR pools goes through the water intake stage, aeration stage, and sedimentation stage in sequence to complete the purification of sewage. Aeration of the corresponding SBR pool is achieved through a fan, and aeration of other SBR pools is achieved through corresponding branch pipes. Only one fan can be used to aerate multiple SBR pools, thereby reducing the number of fans used and reducing usage costs. Each SBR pool enters the water intake stage, aeration stage, and sedimentation stage in sequence according to the time sequence. The time when each SBR pool enters each stage is different and follows the time sequence, so that several SBR pools enter each stage in a regular manner, thereby ensuring that, at the same time, only one fan can meet the aeration requirements of several groups of SBR pools.

[0022] Optionally, before step S1, the method further includes: adjusting the opening size of the ball valve on each branch pipeline.

[0023] By adopting the above technical solution, the ball valve is opened to the corresponding size before starting, so that the ventilation volume of the branch pipeline is determined before starting, making it unnecessary to readjust the size of the ball valve during use, thereby facilitating the use of the branch pipeline.

[0024] Optionally, in step S21, there are several aeration states of the sewage in the SBR tank, and the several aeration states are divided according to the amount of air intake required for aeration; at the same time, the aeration states of the several SBR tanks are different.

[0025] By adopting the above technical solution, multiple aeration states are divided according to the size of the air intake, and the oxygen content in the SBR pool is changed by changing the size of the air intake, so that the SBR pool can switch between carbonization and nitrification caused by eutrophic reaction and denitrification caused by anoxic reaction under the aeration state.

[0026] Optionally, in step S21, among the plurality of SBR tanks in the aeration state, there is only one SBR tank in the aeration state requiring the largest air intake.

[0027] By adopting the above technical solution, when there are two SBR pools that require the same air intake volume and both are greater than the air intake volume required by other SBR pools, two fans must be turned on, which leads to increased power consumption; therefore, when ensuring that only one SBR pool among several SBR pools in the aeration stage is in the aeration state with the largest required air intake volume, only one fan needs to be turned on, and the aeration of other SBR pools can be achieved by turning on the corresponding branch pipes, thereby reducing power consumption.

[0028] Optionally, in step S22, the SBR tank connected to the turned-on blower is in an aeration state where the required air intake volume is the largest.

[0029] By adopting the above technical solution, since no flow control valve is set on the ventilation pipe, when the fan is turned on, the aeration tank connected to the fan has the largest air intake at this time, so the fan corresponding to the aeration tank with the largest air intake needs to be turned on.

[0030] Optionally, in step S2, each of the SBR tanks passes through all aeration states in sequence and the existence time of each aeration state is the same.

[0031] By adopting the above technical solution, all SBR pools will pass through all aeration states in sequence and the existence time of each aeration state is the same, so that all SBR pools will change regularly with time sequence, and the opening of the fan will also change with the regularity, satisfying the coordination relationship between several SBR pools and several fans.

[0032] Optionally, in step S22, at the same time, only one of the fans is in the on state.

[0033] By adopting the above technical solution, the operation of one fan can reduce power consumption.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. Through the setting of ventilation channels and branch pipes, one fan can simultaneously supply air of different flow rates to multiple SBR tanks, thereby greatly reducing operating power consumption.

[0036] 2. The ball valve and solenoid valve on the branch pipe can be set to control the air intake into the corresponding SBR pool, realize different aeration states of the SBR pool, realize the transition between carbonization and nitrification reaction under eutrophic conditions and denitrification reaction under anoxic conditions, and increase the purification effect of sewage.

[0037] 3. Each SBR pool enters the water intake stage, aeration stage and sedimentation stage in sequence, and each SBR pool enters each stage at a different time and in sequence, so that several SBR pools enter each stage in a regular manner, thereby ensuring that only one fan is needed to meet the aeration requirements of several groups of SBR pools. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the fan system in this application.

[0039] Figure 2 This is the water inlet and outlet timing table of the four groups of SBR tanks in the fan system control method of this application.

[0040] Figure 3 This is a piping connection diagram of four groups of fans and four groups of SBR tanks in the fan system control method of this application.

[0041] In the figure, 1. SBR tank; 2. Fan; 3. Ventilation pipe; 4. Branch pipe; 5. Solenoid valve; 7. Ball valve. DETAILED DESCRIPTION

[0042] The following is combined with Figure 1 -Attached Figure 3 , further details of this application are given.

[0043] A fan 2 system suitable for rural sewage SBR treatment, refer to Figure 1 , including several SBR tanks 1, several aeration pipes are arranged at the bottom of the SBR tank 1, and several aeration holes are opened on the aeration pipes. The aeration pipes are interconnected with the corresponding ventilation pipes 3, so that the SBR tank 1 can discharge sewage, aerate and purify the sewage, and precipitate it, so that the sewage can be discharged after treatment, reducing the pollution level of the sewage.

[0044] Several SBR pools 1 are each provided with a corresponding number of fans 2, and the fans 2 are arranged in a one-to-one correspondence with the SBR pools 1, and each fan 2 is correspondingly provided with a ventilation pipe 3, one end of the ventilation pipe 3 is interconnected with the air outlet of the fan 2, and the other end is interconnected with the aeration pipe inside the corresponding SBR pool 1, so that the SBR pool 1 can be ventilated through the fan 2 to realize the aeration process.

[0045] Each ventilation pipe 3 is connected to a branch pipe 4, and the branch pipe 4 is connected to the adjacent ventilation pipes 3 in sequence. The branch pipe 4 on the last ventilation pipe 3 is connected to the first ventilation pipe 3. A solenoid valve 5 and a ball valve 7 are provided on the branch pipe 4. The opening amount of the branch pipe 4 can be controlled by the setting of the ball valve 7, and the opening and closing of the branch pipe 4 can be controlled by the setting of the solenoid valve 5. Through the cooperation of the ventilation pipe 3 and the branch pipe 4, one fan 2 can be turned on and multiple SBR tanks 1 can be aerated at the same time. By adjusting the ball valve 7 of the corresponding branch pipe 4, the air intake of the corresponding SBR tank 1 can be changed, thereby realizing aeration with different air intakes, and then changing the oxygen content in the SBR tank 1 during the aeration process, realizing eutrophication reaction and anoxic reaction and other purification of sewage.

[0046] The implementation principle of the embodiment of the present application is: a fan 2 cooperates with the ventilation pipe 3 and the branch pipe 4 to play the role of a variable frequency fan 2, and at the same time, through the linkage of multiple fans 2, the aeration of multiple SBR tanks 1 can be controlled at the same time.

[0047] A fan 2 system control method suitable for rural sewage SBR treatment, referring to Figure 1 , the explanation is given by taking four groups of SBR pools 1, four fans 2, aeration status divided into two types: low air intake aeration status (referred to as "low aeration") and high air intake aeration status (referred to as "high aeration"), water inlet time 30 minutes, low aeration time 30 minutes, high aeration time 30 minutes and sedimentation time 30 minutes as an example.

[0048] However, the number of SBR tanks 1 and fans 2 is not limited to four groups, the aeration state is not limited to low aeration and high aeration, and the time of each stage is not limited to 30 minutes. The number of SBR groups, the number of aeration states and the operating time of each stage can be adjusted according to the setting of the operating cycle, but the pipeline connection and operation mode of the fan 2 can be achieved by the method described in this application.

[0049] The sewage purification process of a single SBR tank 1 is as follows:

[0050] The water inlet stage lasts for 30 minutes, and the aeration stage lasts for 60 minutes. The 60 minutes of the aeration stage include 30 minutes of low aeration and 30 minutes of high aeration, and then enters the sedimentation stage for 30 minutes. After completion, SBR pool 1 re-enters the water inlet stage for 30 minutes. The SBR pool 1 switches between different stages with a time period of 30 minutes.

[0051] The sewage purification process of the four groups of SBR tanks 1 is as follows:

[0052] S0: Adjust the opening size of the ball valve 7 on each branch pipe 4.

[0053] Each SBR pool 1 is provided with two air paths, namely a ventilation pipe 3 and a branch pipe 4. The two ends of the ventilation pipe 3 are respectively connected with the fan 2 and the corresponding SBR pool 1. The ventilation pipe 3 can exhaust the maximum air intake into the corresponding SBR pool 1, so that the corresponding SBR pool 1 can meet the air intake of the high explosion state.

[0054] The two ends of the branch pipe 4 are connected to the corresponding two ventilation pipes 3 respectively. No valve is set on the ventilation pipe 3. A solenoid valve 5 is set on the branch pipe 4. The solenoid valve 5 controls the opening and closing of the corresponding ventilation pipe 3. At the same time, a ball valve 7 is set. The size of the opening of the ball valve 7 is used to control the size of the air flow through the branch pipe 4, thereby controlling the size of the air intake of the exhaust gas in the corresponding SBR tank 1 through the branch pipe 4, so that the branch pipe 4 can meet the air intake of each SBR tank 1 in the low exposure state.

[0055] Before the SBR pool 1 starts to discharge sewage, the ball valve 7 on each branch pipe 4 needs to be adjusted to meet the air intake volume of the corresponding low exposure state of the SBR pool 1. Since the low exposure state is jointly controlled by the ball valve 7 and the solenoid valve 5, the ball valve 7 will not be adjusted for the second time after the adjustment is completed. Therefore, in the subsequent description, it is assumed that all ball valves 7 are in the open state, and the start and stop of the branch pipe 4 corresponding to the low exposure state of the SBR pool 1 only need to be realized by opening and closing the solenoid valve 5.

[0056] S1: Sewage is discharged into several groups of SBR tanks 1 in chronological order, so that several groups of SBR tanks 1 enter the water inlet stage in turn.

[0057] S2: After sewage is discharged into the corresponding SBR pool 1, the SBR pool 1 filled with sewage enters the aeration stage, and several groups of SBR pools 1 enter the aeration stage in sequence;

[0058] S21: Among several groups of SBR pools 1, at least two SBR pools 1 are in the aeration stage at the same time, and when several SBR pools 1 are in the aeration stage, the air intake required by the several SBR pools 1 in the aeration stage are all different.

[0059] When there are only two aeration states, low aeration and high aeration, among the four groups of SBR pools 1, there are always two SBR pools 1 in the aeration state, and one of them is in the low aeration state, and the other is in the high aeration state at the same time, and there is only one SBR pool 1 in the high aeration state.

[0060] Several groups of SBR pools 1 enter the water inlet stage in chronological order, which makes several groups of SBR pools 1 enter the aeration stage in chronological order, and finally makes several groups of SBR pools 1 enter the sedimentation stage in chronological order, so that the states of several groups of SBR pools 1 will show regular changes.

[0061] Reference Figure 2 , the four groups of SBR tanks 1 are continuously fed with water at intervals of 30 minutes. The water inflow and outflow patterns are as follows:

[0062] Initial state: SBR pool 1 is in low exposure state, SBR pool 1 is in high exposure state, SBR pool 1 is in sedimentation state, and SBR pool 1 is in water inflow state;

[0063] After the first 30 minutes: SBR pool 1 is in high exposure state, SBR pool 1 is in sedimentation state, SBR pool 1 is in water inflow state, and SBR pool 1 is in low exposure state;

[0064] After the second 30 minutes, SBR pool 1 is in the sedimentation state, SBR pool 1 is in the water inflow state, SBR pool 1 is in the low aeration state, and SBR pool 1 is in the high aeration state;

[0065] After the third 30 minutes, SBR pool 1 is in the water inflow state, SBR pool 1 is in the low aeration state, SBR pool 1 is in the high aeration state, and SBR pool 1 is in the sedimentation state;

[0066] After the fourth 30 minutes, SBR pool 1-1 is in the low exposure state, SBR pool 1-2 is in the high exposure state, SBR pool 1-3 is in the sedimentation state, and SBR pool 1-4 is in the water inflow state;

[0067] The subsequent state repeats the above first 30 minutes to the fourth 30 minutes, and so on.

[0068] Through the above-mentioned timing changes, the two SBR tanks 1 in the aeration state will continuously change according to the above-mentioned order, so that the branch pipe 4 only needs to be set between two adjacent SBR tanks 1 and between the first SBR tank 1 and the last SBR tank 1, which can reduce the length of the branch pipe 4.

[0069] S22: Start a fan 2 to ventilate the corresponding SBR tank 1 through the ventilation pipe 3, and open the corresponding branch pipe 4 on the ventilation pipe 3 to ventilate the SBR tank 1 connected to the branch pipe 4;

[0070] When an SBR pool 1 is in a high-explosion state, the corresponding fan 2 is turned on. At this time, the ventilation volume of the SBR pool 1 in the high-explosion state is the largest, realizing aeration in an oxygen-rich state; at the same time, when an SBR pool 1 is in a low-exposure state, the branch pipe 4 between the ventilation pipe 3 of the SBR pool 1 in the high-explosion state and the ventilation pipe 3 of the SBR pool 1 in the low-exposure state is opened to realize aeration of the SBR pool 1 in the low-exposure state in an oxygen-deficient state.

[0071] The number of fans 2 is the same as that of SBR pools 1, both of which are four groups. By switching the four groups of fans 2 and opening the corresponding branch pipes 4, only one fan 2 needs to be turned on when aerating two SBR pools 1, which greatly reduces the operating power consumption.

[0072] Reference Figure 3 , the connection and operation logic of fan 2 and ventilation pipeline branch pipe are as follows:

[0073] The ventilation pipe 3 of the SBR tank 1 is connected to the fan 2, and the branch pipe 4 is connected to the fan 2. The branch pipe 4 is provided with a ball valve 7 and a solenoid valve 5.

[0074] The ventilation pipe 3 corresponding to the SBR tank 1 is connected to the fan 22, and the corresponding branch pipe 4 is connected to the fan 23. The branch pipe 4 is provided with a ball valve 72 and a solenoid valve 52;

[0075] The ventilation pipe 3 corresponding to the SBR tank 1 is connected to the fan 23, and the corresponding branch pipe 4 is connected to the fan 24. The branch pipe 4 is provided with a ball valve 73 and a solenoid valve 53;

[0076] The corresponding ventilation pipe 3 of SBR tank 1 2 is connected from fan 2 2, and the corresponding branch pipe 4 is connected from fan 2 1. A ball valve 7 2 and a solenoid valve 5 2 are provided on the branch pipe 4.

[0077] The corresponding operating modes can be summarized into the following four types:

[0078] Mode 1: When SBR pool 1- is in low aeration state, SBR pool 1-2 is in high aeration state, solenoid valve 5-1 is open, solenoid valve 5-2, solenoid valve 5-3 and solenoid valve 5-4 are closed, fan 2-2 is running, and fan 2-1, fan 2-3 and fan 2-4 are stopped;

[0079] Mode 2: When SBR pool 1- is in high aeration state, SBR pool 1-4 is in low aeration state, solenoid valve 5-4 is open, solenoid valve 5-1, solenoid valve 5-2 and solenoid valve 5-3 are closed, fan 2-1 is running, and fans 2-2, 2-3 and 2-4 are stopped;

[0080] Mode 3: When SBR pool 14 is in high aeration state, SBR pool 13 is in low aeration state, solenoid valve 53 is open, solenoid valve 51, solenoid valve 52 and solenoid valve 53 are closed, fan 24 is running, and fans 21, 22 and 23 are stopped;

[0081] Mode 4: When SBR pool 13 is in high aeration state, SBR pool 12 is in low aeration state, solenoid valve 52 is open, solenoid valve 51, solenoid valve 53 and solenoid valve 54 are closed, fan 23 is running, and fan 21, fan 22 and fan 24 are stopped;

[0082] After mode 4 is finished, it returns to mode 1 and repeats this process.

[0083] When the states of several SBR tanks 1 change regularly with the timing, the fan 2 and the solenoid valve 5 will also change regularly, so that under the premise of ensuring the normal operation of the four groups of SBR tanks 1, only one fan 2 is turned on at the same time to reduce power consumption.

[0084] S3: The aerated SBR tank 1 is subjected to sedimentation, and several SBR tanks 1 enter the sedimentation stage in sequence;

[0085] S4: the SBR tank 1 discharges wastewater after sedimentation;

[0086] S5: Each of the SBR tanks 1 repeats the above S1-S4 in sequence.

[0087] The implementation principle of the embodiment of the present application is: one fan 2 can simultaneously drive two groups of SBR tanks 1 to perform aeration with different air intakes, thereby reducing the number of fans 2 required for aeration and reducing the power consumption required to operate the fans 2.

[0088] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A fan system control method suitable for SBR treatment of rural sewage, characterized in that: The invention relates to a fan system suitable for SBR treatment of rural sewage, wherein the fan system comprises a plurality of fans (2) and a plurality of SBR tanks (1) arranged in sequence, wherein the plurality of fans (2) are arranged in a one-to-one correspondence with the plurality of SBR tanks (1), and each of the fans (2) is provided with a corresponding ventilation pipe (3), and both ends of the ventilation pipe (3) are respectively connected to the air outlet of the fan (2) and the interior of the corresponding SBR tank (1); each of the ventilation pipes (3) is connected to a branch pipe (4), and the branch pipe (4) is also connected to the adjacent ventilation pipes (3) in sequence, and the branch pipe (4) on the last ventilation pipe (3) is connected to the first ventilation pipe (3); and each of the branch pipes (4) is provided with a ball valve (7) and a solenoid valve (5); return The following steps are involved: S1: sewage is discharged into the SBR tank (1), and a plurality of the SBR tanks (1) enter the water inlet stage in sequence; S2: After sewage is discharged into the SBR tank (1), the plurality of SBR tanks (1) enter the aeration stage in sequence; S21: At the same time, among the plurality of SBR tanks (1), two of the SBR tanks (1) are in the aeration stage; In step S21, there are several aeration states of the sewage in the SBR tank (1), and the several aeration states are divided according to the size of the air intake required for aeration; at the same time, the aeration states of the several SBR tanks (1) are different; among the several SBR tanks (1) in the aeration state, there is only one SBR tank (1) in the aeration state requiring the largest air intake; S22: starting one of the blowers (2) to ventilate the corresponding SBR tank (1) through the ventilation pipe (3), and opening the corresponding branch pipe (4) on the ventilation pipe (3) to ventilate the SBR tank (1) that is interconnected with the branch pipe (4); In step S22, the SBR tank (1) connected to the turned-on blower (2) is in an aeration state where the required air intake volume is the largest; S3: The aerated SBR tank (1) is subjected to sedimentation, and a plurality of SBR tanks (1) enter the sedimentation stage in sequence; S4: the SBR tank (1) discharges wastewater after sedimentation; S5: Repeat the above steps S1 to S4 in each of the SBR tanks (1) in sequence.

2. A fan system control method suitable for rural sewage SBR treatment according to claim 1, characterized in that, Before step S1, the method further includes: adjusting the opening size of the ball valve (7) on each branch pipe (4).

3. A fan system control method suitable for rural sewage SBR treatment according to claim 1, characterized in that: In step S2, each of the SBR tanks (1) passes through all aeration states in sequence and the existence time of each aeration state is the same.

4. A fan system control method suitable for rural sewage SBR treatment according to claim 1, characterized in that, In step S22, at the same time, there is only one fan (2) in the on state.

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