A backwashing control method and device for use in biological filtration devices

Abstract

This application discloses a backwashing control method and device for a biological filtration device. The method includes: providing a biological filtration device and a central controller; continuously acquiring the real-time pressure difference and dissolved oxygen concentration difference between the influent and effluent water in each filtration chamber; calculating the biofilm load index of each filtration chamber based on the real-time pressure difference and dissolved oxygen concentration difference; when the biofilm load index of any filtration chamber exceeds a preset load threshold, controlling the drive motor to rotate the moving valve of the water distribution component, so that the backwash liquid inlet is aligned with that filtration chamber to perform an independent backwashing operation, while the remaining filtration chambers maintain normal filtration through normal effluent outlets. This application can accurately remove aged biofilm and clumped dead zones without interrupting the main influent flow path, maintaining continuous and stable overall water treatment capacity.

Description

Technical Field

[0001] This application relates to the field of high-end environmental protection equipment and automation control technology, and more specifically, to a backwashing control method and equipment applied to a biological filtration device. Background Technology

[0002] In high-density land-based recirculating aquaculture systems, fixed-bed biofilters function by converting ammonia nitrogen in the water through nitrifying bacteria attached to the filter media. With increasing operating time, the biofilm on the filter media surface thickens, trapping various suspended solids in the water, leading to a significant increase in the hydraulic resistance of the filter layer. Traditional backwashing techniques generally employ a global simultaneous backwashing mode. In this mode, the main inlet flow path must be completely shut off during backwashing, causing a sharp drop in the overall nitrification capacity of the system during and after backwashing, resulting in temporary exceedances of ammonia nitrogen concentration in the aquaculture ponds and affecting water quality stability.

[0003] Existing automatic backwashing systems primarily rely on single-dimensional triggering mechanisms, such as upstream and downstream liquid level differences or preset timers. Due to the fluid dynamics principle of following the path of least resistance, when agglomeration occurs within the filter bed, causing a sharp increase in local resistance, the backwash water will bypass these high-resistance areas and flow instead to relatively clean areas with lower resistance. This results in localized dead zones within the filter bed not receiving sufficient hydraulic shear force and failing to be thoroughly cleaned. Single-dimensional hydraulic triggering mechanisms cannot accurately reflect the actual thickness and activity state of the biofilm, leading to over-rinsing in some areas, stripping away effective nitrifying bacteria, or under-rinsing in some dead zones, triggering localized anaerobic fermentation and producing hydrogen sulfide gas. Summary of the Invention

[0004] This embodiment provides a backwashing control method and device for a biological filtration device, which solves the problems of intermittent loss of system processing capacity caused by global backwashing in existing biological filtration devices, and the inability of traditional single hydraulic backwashing to completely eliminate local dead zones inside the filter bed.

[0005] This application provides a backwashing control method for a biological filtration device, comprising: providing a biological filtration device and a central controller; the biological filtration device including a tank, a water distribution assembly, a drive motor, a differential pressure transmitter, an inlet dissolved oxygen sensor, and an outlet dissolved oxygen sensor; the tank being divided into multiple filtration chambers by radial partitions, each filtration chamber being filled with packing material; the water distribution assembly being located at the bottom of the tank, and including an annular valve seat and a movable valve disc; the annular valve seat connecting each filtration chamber; the movable valve disc being located below the annular valve seat, and having a backwash liquid inlet and a normal water outlet; the drive motor being connected to the movable valve disc via a transmission shaft; and the differential pressure transmitter being installed in each filtration chamber. The tank's main inlet pipe is equipped with the inlet dissolved oxygen sensor, and the tank's main outlet pipe is equipped with the outlet dissolved oxygen sensor. The system continuously acquires the real-time differential pressure feedback from the differential pressure transmitters in each of the filter chambers; it acquires the inlet and outlet dissolved oxygen concentration differences fed back by the inlet and outlet dissolved oxygen sensors; based on the real-time differential pressure and the inlet and outlet dissolved oxygen concentration differences, it calculates the biofilm load index for each filter chamber; when the biofilm load index of any filter chamber exceeds a preset load threshold, it controls the drive motor to rotate the moving valve, aligning the flushing fluid inlet with that filter chamber, independently injecting backwash fluid into that filter chamber to perform a backwashing operation, while keeping the remaining filter chambers in normal filtration state through the normal outlet.

[0006] In one possible implementation, the biofiltration device further includes a support plate disposed at the bottom of each of the filter chambers, the differential pressure transmitter includes a first pressure tap and a second pressure tap, the first pressure tap being disposed above the support plate and the second pressure tap being disposed below the top of the packing; the cross-sectional area of ​​the flushing fluid inlet on the moving valve disc is equal to the bottom cross-sectional area of ​​a single filter chamber.

[0007] In one possible implementation, the tank is made of 316L stainless steel, and the interior of the tank is divided into eight fan-shaped filter chambers by eight radial baffles made of polytetrafluoroethylene; the packing material is a ceramic porous particle packing material with a porosity between 85% and 92%.

[0008] In one possible implementation, the drive motor is a stepper motor with a Hall encoder;

[0009] Controlling the drive motor to drive the moving valve disc to rotate includes: obtaining the absolute position feedback from the Hall encoder and controlling the drive motor to drive the transmission main shaft to rotate, so as to rotate the moving valve disc to an absolute angle corresponding to the filter chamber.

[0010] In one possible implementation, the biofilm loading index of each of the filter chambers is calculated based on the real-time pressure difference and the influent / effluent dissolved oxygen concentration difference, including: obtaining the ratio of the real-time pressure difference to the initial pressure difference to obtain a pressure difference coefficient; obtaining the difference between the baseline oxygen consumption and the influent / effluent dissolved oxygen concentration difference, and multiplying the ratio of the difference to the baseline oxygen consumption by an empirical compensation coefficient to obtain an oxygen consumption compensation coefficient; adding a constant 1 to the oxygen consumption compensation coefficient to obtain an oxygen consumption correction factor; and multiplying the pressure difference coefficient by the oxygen consumption correction factor to obtain the biofilm loading index.

[0011] In one possible implementation, the initial pressure difference is 2.5 kPa, the baseline oxygen consumption is 1.5 mg / L, the empirical compensation coefficient ranges from 0.3 to 0.5, and the preset load threshold is 2.8.

[0012] In one possible implementation, backwashing is performed by independently injecting backwash fluid into the filter chamber, including: turning on an air-water mixing pump connected to the flushing fluid inlet, injecting the air-water mixing fluid into the bottom of the filter chamber, and driving the air-water mixing fluid to flow upward along the physical boundary formed by the radial partition to flush the packing material inside the filter chamber.

[0013] In one possible implementation, injecting an air-water mixture into the bottom of the filter chamber includes:

[0014] Open the pneumatic regulating valve and inject compressed air at a pressure of 0.15MPa into the bottom of the filter chamber through the flushing liquid inlet for 15 seconds;

[0015] Then, the pneumatic regulating valve is closed, and the backwash water pump is turned on to inject high-pressure water into the filter chamber through the flushing liquid inlet at a flushing intensity of 12L / (m²·s) for 45 seconds.

[0016] In one possible implementation, during the backwashing operation performed by independently injecting backwash fluid into the filter chamber, the real-time differential pressure drop rate within the filter chamber is monitored simultaneously; in response to detecting that the real-time differential pressure drop rate is lower than the attenuation derivative threshold and the real-time differential pressure falls back to the initially set range, a stop command is sent to the air-water mixing pump to terminate the injection of the air-water mixing fluid, and the drive motor is controlled to rotate the moving valve disc in the reverse direction to the reset state, so that the filter chamber is reconnected to the normal water outlet.

[0017] This application also provides a backwashing control device for implementing the backwashing control method for biological filtration devices provided in this application.

[0018] Based on the above technical solutions, this application embodiment combines radial isolation of physical space with a bottom servo rotating water distribution component. When performing a fixed-point backwashing operation in a high-load filter chamber, the remaining filter chambers maintain a conventional filtration flow line, ensuring the continuity and stability of the overall nitrification capacity of the water treatment system. This application utilizes a biofilm load index algorithm based on the coupling of pressure differential decay and oxygen consumption decay parameters, breaking the limitations of a single water flow triggering mechanism. This algorithm can detect the clogging status inside the filter bed and dynamically guide air-water pulse backwashing. Radial baffles restrict the lateral escape of high-pressure backwash fluid to adjacent low-resistance areas, ensuring that algorithm commands are converted into localized, concentrated high-energy hydraulic jets, achieving the stripping of aging biofilm and agglomerated dead zones. Attached Figure Description

[0019] Figure 1 This is a schematic cross-sectional view of the biological filtration device provided in an embodiment of the present invention.

[0020] Figure 2 This is a structural block diagram of the backwashing control device provided in an embodiment of the present invention.

[0021] Figure 3 This is a schematic flowchart of the backwashing control method provided in an embodiment of the present invention.

[0022] In the diagram: 100-Biological filtration device, 101-Tank body, 102-Radial baffle, 103-Filter chamber, 104-Packing material, 105-Servo rotary water distribution assembly, 106-Annular valve seat, 107-Moving valve disc, 108-Flushing fluid inlet, 109-Normal effluent outlet, 110-Drive motor, 111-Transmission spindle, 112-Support plate, 113-Inlet main pipe, 114-Overflow drain pipe, 115-Inlet dissolved oxygen sensor, 116-Outlet dissolved oxygen sensor, 117-Miniature differential pressure transmitter, 117a-First pressure tap, 117b-Second pressure tap, 118-Air-water mixing pump. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments of this application are merely for explaining this application and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0024] Figure 1 The physical hardware foundation of this embodiment is shown. For example... Figure 1As shown, this application provides a biological filtration device 100, the main structure of which is an upright cylindrical pressure-resistant tank 101. The tank 101 is made of 316L stainless steel, possessing industrial-grade high pressure resistance and seawater corrosion resistance. Inside the tank 101, eight vertically arranged radial baffles 102 completely divide the entire internal space into eight independent filtration chambers 103 with fan-shaped cross-sections. The radial baffles 102 are made of polytetrafluoroethylene (PTFE). Each filtration chamber 103 is filled with packing material 104. The packing material 104 is a porous ceramic particle packing material with a porosity between 85% and 92%, providing a large specific surface area for nitrifying bacteria to attach. A support plate 112 for supporting the structure is provided at the bottom of the packing material 104 layer. The top of the tank 101 is equipped with an inlet main pipe 113 for introducing raw water and an overflow drain pipe 114 for draining flushing wastewater. The design of these eight independent filter chambers 103 can prevent the lateral disorderly spread of backwash fluid from a physical spatial perspective, thereby providing a physical framework support for localized directional cleaning.

[0025] In the water collection area at the bottom of tank 101, a servo rotary water distribution assembly 105 for flow path switching is configured. The servo rotary water distribution assembly 105 includes a fixed annular valve seat 106 and a movable valve disc 107 that movably fits below the annular valve seat 106. The annular valve seat 106 has through holes that correspond one-to-one with the bottom ends of the eight independent filter chambers 103 above. The movable valve disc 107 has a dedicated flushing fluid inlet 108 and a larger normal water outlet 109. The cross-sectional area of ​​the flushing fluid inlet 108 on the movable valve disc 107 is configured to be equal to the bottom cross-sectional area of ​​a single filter chamber 103, ensuring that the flushing fluid can fully cover the sector. A coaxial drive shaft 111 extending through the bottom of tank 101 is connected to the center of the movable valve disc 107. The outer end of the drive shaft 111 is mechanically connected to a drive motor 110 via a reducer. The drive motor 110 is a stepper motor with a Hall encoder. By obtaining the absolute position feedback from the Hall encoder, the actuated valve disc 107 can be rotated to the corresponding angle. All sealing connections are reliably sealed using flange faces and fluororubber O-rings. This bottom-rotating distribution structure, combined with the top-drainage design, places the system's kinetic energy switching mechanism in a stable water flow zone, reducing hydraulic disturbance.

[0026] To acquire operational data, the biological filtration device 100 employs a high-density sensor network. An inlet dissolved oxygen sensor 115 is installed on the inlet main pipe 113, and an outlet dissolved oxygen sensor 116 is installed at the main outlet pipe below the annular valve seat 106. For each individual filter chamber 103, a pair of miniature differential pressure transmitters 117 are embedded. Each miniature differential pressure transmitter 117 includes a first pressure tap 117a and a second pressure tap 117b. The first pressure tap 117a is positioned 10 cm above the support plate 112, and the second pressure tap 117b is positioned 10 cm below the top surface of the packing material 104. This arrangement of pressure measurement points avoids end effects at both ends of the filter bed, capturing the hydraulic resistance state of the core working layer.

[0027] The system of this application is also equipped with peripheral actuators and energy supply modules, including an external air compressor for generating high-pressure gas, a high-pressure water pump for providing a stable flushing water source, and an air-water mixing pump 118 formed by the combination of the two. The output end of the air-water mixing pump 118 is connected to the flushing liquid inlet 108 at the bottom through a pipeline system and control valves. The system is equipped with a power drive circuit and a power supply module for driving the stepper motor, pneumatic regulating valve, and water pump to provide the electrical energy and driving force required for the operation of the underlying hardware.

[0028] like Figure 2 As shown in the illustration, this application provides a backwashing control device. This control device is equipped with a central controller (e.g., an industrial-grade programmable logic controller, PLC) with a specific algorithm program. The backwashing control device includes an acquisition module, a concentration difference calculation module, a load calculation module, and a backwashing execution module. The entire backwashing control device establishes a data link with all the aforementioned sensors and drive components via the Modbus RTU communication protocol. The module division here logically illustrates the functional set of the central controller; all the aforementioned modules can be implemented by executing program code in the memory of the central controller's built-in microprocessor.

[0029] like Figure 3 The diagram illustrates the workflow of a backwashing control method provided in this embodiment. This method relies on a backwashing control device to coordinate the execution of the biological filtration unit 100. The specific steps of this process are explained below:

[0030] S301: During the continuous acquisition of real-time differential pressure, the central controller continuously reads and acquires the real-time differential pressure fed back by the miniature differential pressure transmitters 117 inside each filter chamber 103 through the communication protocol. High-frequency sampling ensures timely capture of sudden changes in fluid conditions.

[0031] S302: During the process of obtaining the dissolved oxygen concentration difference between the influent and effluent, the central controller synchronously obtains the oxygen concentration data fed back in real time by the dissolved oxygen sensor 115 and the dissolved oxygen sensor 116, and performs a subtraction calculation to obtain the current dissolved oxygen concentration difference between the influent and effluent of the entire biological filtration device.

[0032] S303: In the calculation of the biofilm loading index, the central controller calculates the biofilm loading index (BBI) of each filter chamber 103 based on the acquired real-time pressure difference and the influent / effluent dissolved oxygen concentration difference. Traditional backwash control only considers the pressure difference, which can easily lead to misjudgment. This application combines physical resistance with biological oxygen consumption. The central controller obtains the ratio of the real-time pressure difference of each filter chamber 103 to the initial pressure difference to obtain the pressure difference coefficient; obtains the difference between the baseline oxygen consumption and the influent / effluent dissolved oxygen concentration difference, and multiplies the ratio of this difference to the baseline oxygen consumption by an empirical compensation coefficient to obtain the oxygen consumption compensation coefficient; adds the constant 1 to the oxygen consumption compensation coefficient to obtain the oxygen consumption correction factor; multiplies the pressure difference coefficient and the oxygen consumption correction factor to obtain the biofilm loading index representing the overall clogging and activity status of the filter chamber. Through this product amplification logic, the system can balance the combined effects of physical particulate matter retention and biofilm metabolism on the filter bed life.

[0033] The biofilm loading index is calculated using the following mathematical expression:

[0034]

[0035] Where n represents the number of each independent filter chamber 103. Since the tank is divided into eight equal parts, the value of n ranges from n=1 to 8.

[0036] This represents the biofilm load index of the nth filter chamber 103 calculated by the system.

[0037] This represents the real-time differential pressure data fed back by the miniature differential pressure transmitter 117 in the nth filter chamber 103.

[0038] This indicates the initial pressure difference calibrated by the packing 104 in a clean state. This parameter serves as the denominator for the physical resistance and has a preset value of 2.5 kPa stored in the system.

[0039] This indicates the baseline oxygen consumption of the recirculating aquaculture system when it is operating healthily under the current given flow conditions. This baseline parameter is set at 1.5 mg / L.

[0040] This represents the difference in dissolved oxygen concentration between the influent and effluent water, measured and calculated by the dissolved oxygen sensors.

[0041] This represents the empirical compensation coefficient of the algorithm, used to adjust the degree of interference of biological oxygen consumption fluctuations on the total index. Its value is set between 0.3 and 0.5.

[0042] Through this coupling formula, if the global oxygen consumption shrinks synchronously, the product effect will push up the BBI index of the sector, triggering intelligent cleaning and avoiding the sub-healthy operating state caused by simply waiting for the pressure difference to reach the standard.

[0043] S304: During the threshold determination and backwashing operation, the central controller makes a threshold determination. When the biofilm load index of any filter chamber 103 exceeds the system's preset load threshold (e.g., a threshold is determined), the threshold is determined. When the value exceeds the set threshold (2.8), the central controller issues a drive command. After receiving the command, the drive motor 110 drives the transmission spindle 111 to rotate according to the angular displacement signal fed back by the Hall encoder, which in turn drives the valve disc 107 to rotate, so that the flushing liquid inlet 108 is aligned with the bottom through hole of the annular valve seat of the third filter chamber 103.

[0044] At this time, backwashing fluid is injected independently into the high-load filter chamber to perform a backwashing operation. The central controller opens the pneumatic regulating valve, injecting compressed air at a pressure of 0.15 MPa generated by the external air compressor into the bottom of the filter chamber through the flushing fluid inlet 108. The high-pressure air washing action lasts for 15 seconds, using bubbles to break up severely compacted entrapped material and the outer aged biofilm. Subsequently, the air valve closes, and the control system starts the backwash water pump, injecting high-pressure water flow inward at a flushing intensity of 12 L / (m²·s) for 45 seconds. During the alternating air and water flushing process, the air-water mixture is required to flow upward along the sealed physical boundary formed by the radial baffle 102 to flush the packing 104. During this period, through the mechanical isolation design of the rotating water distribution assembly, the flow paths of the remaining seven filter chambers are still connected to the normal water outlet 109 of the moving valve 107, maintaining normal filtration water flow operation. The concentrated wastewater generated by the single-sector flushing is discharged to a specific channel through the overflow drain pipe at the top of the tank. This divide-and-conquer approach can clean local dead zones while preventing the overall water quality from deteriorating.

[0045] S305: The system also needs to execute safe recovery and reset logic. During the backwashing operation of the filter chamber 103 by independently injecting air-water fluid, the central controller synchronously monitors the feedback of the miniature differential pressure transmitter 117 in the filter chamber 103 and calculates its differential pressure drop rate in real time. In response to detecting that the real-time differential pressure drop rate is lower than the preset attenuation derivative threshold, and the real-time differential pressure absolute value has steadily fallen back to the initial set range (the fallback reset condition is set to the differential pressure drop below 3.0 kPa), once both conditions are met simultaneously, the central controller sends a stop command to the relevant pneumatic valve and water pump to terminate the injection of air-water mixture. Immediately afterwards, the control drive motor 110 rotates the valve disc 107 in the reverse direction according to the preset path to the reset state, so that the cleaned filter chamber 103 is disconnected from the flushing flow path and reconnected to the normal water outlet 109, and connected to the main filtration cycle of the system. Based on the dual termination decision of derivative and absolute value, the active biofilm can be effectively prevented from being accidentally peeled off, protecting the core productivity of the system.

[0046] The backwashing control device and method disclosed in this application constructs a physical framework based on micro-sector segmentation, supplemented by a composite calculation logic coupling differential pressure attenuation and oxygen consumption attenuation. Through the synergistic cooperation of this system, localized dead zones caused by water flow seeking shortcuts are eliminated. While ensuring uninterrupted ammonia nitrogen degradation capacity throughout the entire station, precise hydraulic maintenance is achieved at fixed points, in fixed quantities, and at fixed times, thereby extending the operational life of high-density aquaculture filtration systems.

[0047] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0048] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A backwashing control method for a biological filtration device, characterized in that, include: A biological filtration device and a central controller are provided. The biological filtration device includes a tank, a water distribution assembly, a drive motor, a differential pressure transmitter, an inlet dissolved oxygen sensor, and an outlet dissolved oxygen sensor. The tank is internally divided into multiple filtration chambers by radial partitions, each filled with packing material. The water distribution assembly is located at the bottom of the tank and includes an annular valve seat and a movable valve disc. The annular valve seat connects to each of the filtration chambers, and the movable valve disc is located below the annular valve seat. The movable valve disc has a flushing fluid inlet and a normal water outlet. The drive motor is connected to the movable valve disc via a transmission shaft. The differential pressure transmitter is installed in each filtration chamber, and the main inlet pipe of the tank is connected to the water inlet. A dissolved oxygen sensor is installed on the main outlet pipe of the tank; the real-time differential pressure feedback from the differential pressure transmitter in each of the filter chambers is continuously acquired; the inlet and outlet dissolved oxygen concentration differences are acquired from the inlet and outlet dissolved oxygen sensors; based on the real-time differential pressure and the inlet and outlet dissolved oxygen concentration differences, the biofilm load index of each filter chamber is calculated; when the biofilm load index of any filter chamber exceeds a preset load threshold, the drive motor is controlled to drive the moving valve to rotate, so that the flushing liquid inlet is aligned with the filter chamber, and backwashing fluid is injected independently into the filter chamber to perform a backwashing operation, while the remaining filter chambers maintain normal filtration through the normal outlet.

2. The backwashing control method for a biological filtration device as described in claim 1, characterized in that, The biofiltration device further includes a support plate disposed at the bottom of each of the filter chambers, and the differential pressure transmitter includes a first pressure tap and a second pressure tap, the first pressure tap being disposed above the support plate and the second pressure tap being disposed below the top of the packing; the cross-sectional area of ​​the flushing liquid inlet on the moving valve disc is equal to the bottom cross-sectional area of ​​a single filter chamber.

3. The backwashing control method for a biological filtration device as described in claim 1, characterized in that, The tank is made of 316L stainless steel, and the interior of the tank is divided into eight fan-shaped filter chambers by eight radial baffles made of polytetrafluoroethylene; the packing is a ceramic porous particle packing with a porosity between 85% and 92%.

4. The backwashing control method for a biological filtration device as described in claim 1, characterized in that, The drive motor is a stepper motor with a Hall encoder; Controlling the drive motor to drive the moving valve disc to rotate includes: obtaining the absolute position feedback from the Hall encoder and controlling the drive motor to drive the transmission main shaft to rotate, so as to rotate the moving valve disc to an absolute angle corresponding to the filter chamber.

5. The backwashing control method for a biological filtration device as described in claim 2, characterized in that, Based on the real-time pressure difference and the influent / effluent dissolved oxygen concentration difference, the biofilm loading index of each of the filter chambers is calculated, including: obtaining the ratio of the real-time pressure difference to the initial pressure difference to obtain a pressure difference coefficient; obtaining the difference between the baseline oxygen consumption and the influent / effluent dissolved oxygen concentration difference, and multiplying the ratio of this difference to the baseline oxygen consumption by an empirical compensation coefficient to obtain an oxygen consumption compensation coefficient; adding a constant 1 to the oxygen consumption compensation coefficient to obtain an oxygen consumption correction factor; and multiplying the pressure difference coefficient by the oxygen consumption correction factor to obtain the biofilm loading index.

6. The backwashing control method for a biological filtration device as described in claim 5, characterized in that, The initial pressure difference is 2.5 kPa, the baseline oxygen consumption is 1.5 mg / L, the empirical compensation coefficient ranges from 0.3 to 0.5, and the preset load threshold is 2.

8.

7. The backwashing control method for a biological filtration device as described in claim 1, characterized in that, Performing a backwashing operation by independently injecting backwash fluid into the filter chamber includes: turning on the air-water mixing pump connected to the flushing fluid inlet, injecting the air-water mixing fluid into the bottom of the filter chamber, and driving the air-water mixing fluid to flow upward along the physical boundary formed by the radial partition to flush the packing material in the filter chamber.

8. The backwashing control method for a biological filtration device as described in claim 7, characterized in that, Injecting an air-water mixture into the bottom of the filtration chamber, comprising: Open the pneumatic regulating valve and inject compressed air at a pressure of 0.15MPa into the bottom of the filter chamber through the flushing liquid inlet for 15 seconds; Then, the pneumatic regulating valve is closed, and the backwash water pump is turned on to inject high-pressure water into the filter chamber through the flushing liquid inlet at a flushing intensity of 12L / (m²·s) for 45 seconds.

9. The backwashing control method for a biological filtration device as described in claim 7, characterized in that, During the backwashing operation of the filter chamber by independently injecting backwash fluid, the real-time differential pressure drop rate in the filter chamber is monitored simultaneously. In response to the detection that the real-time differential pressure drop rate is lower than the attenuation derivative threshold and the real-time differential pressure falls back to the initial set range, a stop command is sent to the air-water mixing pump to terminate the injection of the air-water mixing fluid, and the drive motor is controlled to rotate the moving valve disc in the reverse direction to the reset state, so that the filter chamber is reconnected to the normal water outlet.

10. A backwashing control device, characterized in that, This is for implementing the backwashing control method for a biofiltration device as described in any one of claims 1 to 9.

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