A sewage treatment system for strengthening stable operation of an AOA-MBBR process

Abstract

The utility model provides a kind of wastewater treatment system of reinforced AOA-MBBR process stable operation, including secondary sedimentation tank, the periphery of secondary sedimentation tank is sequentially provided with anaerobic tank, first MBBR aerobic tank, second MBBR aerobic tank, first anoxic tank, second anoxic tank, filter tank;First and second MBBR aerobic tank are equipped with several combined suspended fillers, the outlet of two MBBR aerobic tanks is installed with cylindrical screen, and float ball liquid level meter, aerator are installed in the pool, online dissolved oxygen instrument and ammonia nitrogen on-line monitor are installed in second MBBR aerobic tank, float ball liquid level meter, online dissolved oxygen instrument and ammonia nitrogen on-line monitor are respectively covered with a protective cover outside.AOA-MBBR process is formed by coupling MBBR process and AOA process, wastewater is treated by anaerobic, aerobic, anoxic alternation state, improves total nitrogen and total phosphorus removal rate biological treatment, maximally utilizes raw water organic matter and internal carbon source to achieve the purpose of strengthening biological denitrification and phosphorus removal.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment system for enhancing the stable operation of the AOA-MBBR process. Background Technology

[0002] The AOA (Anaerobic-Oxic-Anoxic) process is designed to address the low-carbon characteristics of municipal wastewater in my country, which is generally characterized by an imbalanced carbon-to-nitrogen ratio. It focuses on energy conservation, pollution reduction, and carbon reduction throughout the entire wastewater treatment process. The aim is to fully utilize the organic matter in the raw water and the carbon sources in the highly efficient circulating sludge to achieve deep nitrogen and phosphorus removal. This is a high-efficiency, land-saving, energy-saving, and chemical-saving low-carbon wastewater treatment process suitable for China's water conditions.

[0003] With the development and application of moving bed biofilm reactors (MBBRs), the inherent defects of fixed biofilm methods, such as oxygen and mass transfer and easy clogging, have been fundamentally improved. MBBRs have advantages such as easy biofilm formation, no clumping, high treatment efficiency, flexible application, low head loss, simple operation, and convenient management. They have gradually become a new type of wastewater treatment technology for enhancing deep nitrogen and phosphorus removal and achieving economic, sustainable, and stable compliance with standards.

[0004] The core of the MBBR (Medium-to-Brain Bioreactor) system involves directly adding suspended media (such as polyethylene, polyurethane, and PPC hydrophilic sponges, primarily in cylindrical and cubic shapes) with a specific gravity close to that of water into the aeration tank as active carriers for microorganisms. These media are fluidized by the aeration and water flow within the tank. When microorganisms attach to the carrier, the biomass enriched on the suspended carrier exhibits characteristics of high quantity, diverse types, and high activity, thus improving the system's treatment load and efficiency. The floating media carrier moves freely as the liquid swirls and rotates, allowing pollutants, water, and air to enter the carrier and react with the microorganisms, achieving the goal of wastewater treatment.

[0005] Currently, the A2 / O process is widely used in most urban and rural wastewater treatment plants in my country. A2 / O is an abbreviation for anaerobic-anoxic-aerobic biological nitrogen and phosphorus removal process. In the A2 / O process, biological nitrogen removal is mainly achieved through aerobic nitrification and anoxic denitrification, while biological phosphorus removal is mainly achieved through anaerobic phosphorus release, aerobic excess phosphorus uptake, and the discharge of excess sludge.

[0006] In recent years, research and development and production verification testing of AOA (Automatic Aeration) technology have begun. Patent application CN201610541851.6 discloses a device and method for continuous-flow AOA deep nitrogen and phosphorus removal from urban domestic sewage. This technical solution breaks through the traditional A2 / O process, realizing the treatment of domestic sewage with low C / N ratios using the AOA process, but it does not mention coupling with the MBBR (Medium-Modulated Batch Reactor) process. Patent application CN202310246452.7 discloses a two-stage AOA sedimentation sewage biochemical treatment device and process. This technical solution mainly considers reducing the amount of sludge flowing into the secondary sedimentation tank from the process end, but does not mention optimizing the secondary sedimentation design to improve the operational stability of the AOA system in response to the differences between AOA and A2 / O.

[0007] With the widespread application of MBBR technology in rural wastewater treatment and emergency treatment projects, MBBR technology has demonstrated outstanding performance in enhancing nitrification and denitrification, increasing the abundance of nitrifying bacteria, increasing volumetric loading, reducing retention time, saving land area, and providing excellent wastewater treatment results. This has increased industry confidence in MBBR technology. In 2021, MBBR technology was included in the newly revised "Outdoor Drainage Design Standard" (GB 50014-2021), which means that its application has been widely recognized by the industry.

[0008] Patent application CN202320530184.7 discloses an AOA wastewater treatment system that facilitates precise control of aeration volume. Based on the dual parameters of dissolved oxygen and ammonia nitrogen, it allows for convenient control of aeration volume, achieving energy saving and consumption reduction. Patent application CN202310419374.6 discloses an AOA system and method for treating urban wastewater with a low carbon-to-nitrogen ratio, which sets different aeration times and volumes based on real-time ammonia nitrogen data in the wastewater. The above solutions mainly describe the control of aeration volume in the AOA process, but neither addresses how to ensure the fluidization of the MBBR packing material, the matching with changes in influent load, and the system's oxygen demand in the coupling of AOA and MBBR. Nor do they consider risk control measures for "accidental contact" of instruments such as online floats during actual operation.

[0009] The existing technology has the following problems:

[0010] 1. Because the A2 / O process requires a high carbon-to-nitrogen ratio to operate, it is not suitable when the carbon-to-nitrogen ratio of the influent to wastewater treatment plants is generally low.

[0011] 2. Mud-film composite processes coupled with MBBR are commonly found in A2 / O, A2 / O-MBBR and A / O-MBBR processes formed by combining with A2 / O. There are few reports on how to ensure the matching of MBBR packing fluidization, organic matter degradation and ammonia nitrogen nitrification with the system's oxygen demand, how to enhance treatment effect, stabilize operation and linkage control in wastewater treatment systems built based on AOA-MBBR.

[0012] 3. The MBBR process is prone to filter clogging and tank flooding due to the accumulation of packing materials and waste. Once tank flooding occurs, it will negatively impact the plant's process operation, economic benefits, and safety. While existing technologies can delay the probability of filter clogging, they cannot completely guarantee that the filters will not become clogged, thus failing to guarantee that the tanks will not flood during normal system operation. Summary of the Invention

[0013] The purpose of this invention is to overcome the above-mentioned problems in the prior art and provide a wastewater treatment system that enhances the stable operation of the AOA-MBBR process.

[0014] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0015] A wastewater treatment system for enhancing the stable operation of the AOA-MBBR process includes a control cabinet and a hexagonal secondary sedimentation tank. Around the secondary sedimentation tank, a hexagonal anaerobic tank, a first MBBR aerobic tank, a second MBBR aerobic tank, a first anoxic tank, a second anoxic tank, and a filtration tank are arranged in sequence. The anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, the secondary sedimentation tank, and the filtration tank are connected in sequence.

[0016] Both the first MBBR aerobic tank and the second MBBR aerobic tank are equipped with several spherical combined suspended packing materials. The outlets of the first MBBR aerobic tank and the second MBBR aerobic tank are equipped with cylindrical screens for intercepting the combined suspended packing materials.

[0017] Both the first MBBR aerobic tank and the second MBBR aerobic tank are equipped with float level gauges and aerators. The second MBBR aerobic tank is equipped with an online dissolved oxygen meter and an online ammonia nitrogen monitor. Each of the float level gauges, online dissolved oxygen meters, and online ammonia nitrogen monitors is covered with a protective cover. The inlet end of the aerator is connected to an aeration blower through a pipe.

[0018] A first electrically controlled valve for controlling the inflow of sewage is installed at the inlet of the anaerobic tank. A first sludge return pipe with a second electrically controlled valve is installed between the secondary sedimentation tank and the anaerobic tank. A second sludge return pipe with a third electrically controlled valve is installed between the secondary sedimentation tank and the first anoxic tank. The control cabinet is connected to a float level gauge, an online dissolved oxygen meter, an online ammonia nitrogen monitor, an aeration blower, the first electrically controlled valve, the second electrically controlled valve, and the third electrically controlled valve via cables.

[0019] The secondary sedimentation tank is a regular hexagon, while the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank are all irregular hexagons. Any two adjacent tanks in the secondary sedimentation tank, anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank share a common side. The secondary sedimentation tank, anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank form an irregular honeycomb shape.

[0020] The anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank all have a smaller volume than the secondary sedimentation tank, while the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank all have the same volume.

[0021] The combined suspended packing includes hollowed-out packing balls and polyurethane sponge packing blocks. Each hollowed-out packing ball contains 6-10 polyurethane sponge packing blocks, and the length, width and height of the polyurethane sponge packing blocks are 15-20mm × 15-20mm × 15-20mm.

[0022] The anaerobic tank is equipped with a fine screen at its inlet to filter out debris from the wastewater.

[0023] The secondary sedimentation tank is equipped with a sludge pump and a sludge discharge pipe for discharging excess sludge. The outlet of the sludge pump is connected to the first sludge return pipe, the second sludge return pipe, and the sludge discharge pipe, respectively. The sludge pump is connected to the control cabinet by a cable.

[0024] The protective cover includes a C-shaped protective cover plate and two L-shaped mounting plates. The two mounting plates are respectively fixed to the top two sides of the protective cover plate. The opening width of the protective cover plate is smaller than the diameter of the combined suspended packing. A water passage hole is opened at the top of the protective cover plate, and the height of the water passage hole is smaller than the diameter of the combined suspended packing.

[0025] Among them, the cylindrical screen includes an annular stainless steel ring and N "丿"-shaped stainless steel rods. The tail ends of the stainless steel rods are welded to the stainless steel ring, and the N stainless steel rods are arranged in a circular array on the stainless steel ring. The distance between any two adjacent stainless steel rods is less than the diameter of the combined suspended packing.

[0026] Among them, a backwash pipe for preventing the accumulation of the combined suspended packing is installed below the cylindrical screen in the first MBBR aerobic tank and the second MBBR aerobic tank. The inlet end of the backwash pipe is connected to the outlet of the aeration blower through a pipeline.

[0027] Among them, a full-network-communication 4G module with a SIM card slot is installed in the float level gauge.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. An anaerobic tank, a first MBBR aerobic tank, a second MBBR aerobic tank, a first anoxic tank, a second anoxic tank, a secondary sedimentation tank, and a filtration tank are sequentially connected. Combined suspended packing is installed in the first MBBR aerobic tank and the second MBBR aerobic tank respectively. The MBBR process is coupled with the AOA process to form the AOA-MBBR process. Since both sludge and biofilm coexist on the combined suspended packing, the advantage of the biofilm in enriching nitrifying bacteria is prominent. The relative abundance of nitrifying bacteria on the combined suspended carrier is generally about 10%, which is much higher than the proportion of nitrifying bacteria in the activated sludge. Therefore, the AOA-MBBR sludge-biofilm composite process has higher sewage treatment efficiency and stronger environmental stress resistance. The sewage is treated through the alternating states of anaerobic, aerobic (MBBR), and anoxic, improving the biological treatment of the removal rates of total nitrogen and total phosphorus, and maximizing the utilization of raw water organic matter and internal carbon sources to achieve the purpose of strengthening biological nitrogen and phosphorus removal.

[0030] 2. The aerator aerates the first MBBR aerobic tank and the second MBBR aerobic tank to promote the normal fluidization of the combined suspended packing, and promotes the free and smooth rotation of the combined suspended packing in the sewage, increasing the impact and cutting of the air bubbles in the sewage. Moreover, the water flow and air bubbles can pass through the inside of the combined suspended packing, strengthening the shedding and renewal of the aged biofilm and maintaining the activity of the biofilm.

[0031] 3. The anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, the secondary sedimentation tank, and the filtration tank are combined into a special-shaped honeycomb shape of "large inside and small outside", meeting the flexible redundancy of the high solid load of the secondary sedimentation tank in the AOA process. While ensuring that the total amount of microbial flora in the system and the sludge concentration carried by the system are higher, it significantly reduces the risk of the sludge interface in the secondary sedimentation tank rising or even turning over, increasing a certain error tolerance rate, and enabling the AOA process to operate more stably.

[0032] 4. Install cylindrical screens to prevent the combined suspended packing from flowing out with the water and to prevent the combined suspended packing from wandering into other tanks;

[0033] 5. Install float level gauges to monitor the liquid levels in the first MBBR aerobic tank and the second MBBR aerobic tank. If the liquid levels in the first MBBR aerobic tank and the second MBBR aerobic tank rise abnormally, feedback will be sent to the control cabinet, thereby controlling the first electrically controlled valve to reduce the amount of sewage flowing into the anaerobic tank and prevent the risk of flooding in the first MBBR aerobic tank and the second MBBR aerobic tank.

[0034] 6. Cover the float level gauge with a protective cover to prevent the combined suspended packing from accumulating around the float level gauge, causing accidental contact and generating incorrect level monitoring data;

[0035] 7. The dissolved oxygen content and ammonia nitrogen content of the wastewater in the second MBBR aerobic tank are monitored using an online dissolved oxygen meter and an online ammonia nitrogen monitor, respectively. The monitoring data is fed back to the control cabinet, which controls the air volume of the aeration blower to match the aeration volume of the aerator with the changes in the influent volume and water quality. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0037] Figure 1 This is a schematic diagram showing the layout of a portion of the wastewater treatment system in this invention;

[0038] Figure 2 This is a schematic diagram of the structure of the protective cover in this invention;

[0039] Figure 3 This is a schematic diagram of the cylindrical screen structure in this invention;

[0040] Figure 4 This is a schematic diagram of the combined suspended packing material in this invention;

[0041] Figure 5 This is a process flow diagram of the wastewater treatment system in this invention;

[0042] The diagram labels are as follows: 1. Secondary sedimentation tank; 2. Anaerobic tank; 3. First MBBR aerobic tank; 4. Second MBBR aerobic tank; 5. First anoxic tank; 6. Second anoxic tank; 7. Filter tank; 8. First electrically controlled valve; 9. First sludge return pipe; 10. Second electrically controlled valve; 11. Aerator; 12. Cylindrical screen; 1201 Stainless steel ring; 1202 Stainless steel rod; 13. Backflush pipe; 14. Float level gauge; 15. Protective cover; 15. Protective cover plate; 1501 Mounting plate; 1502 Water passage hole; 1503. Online dissolved oxygen meter; 16. Online ammonia nitrogen monitor; 17. Second sludge return pipe; 18. Third electrically controlled valve; 19. Combined suspended packing material; 20. Hollowed-out packing ball; 2002. Polyurethane sponge packing block; 21. Sludge pump; 22. Sludge discharge pipe. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] like Figures 1 to 5 As shown, a wastewater treatment system for enhancing the stable operation of the AOA-MBBR process includes a control cabinet, a hexagonal secondary sedimentation tank 1, and a hexagonal anaerobic tank 2, a first MBBR aerobic tank 3, a second MBBR aerobic tank 4, a first anoxic tank 5, a second anoxic tank 6, and a filter tank 7 arranged sequentially around the secondary sedimentation tank 1. The anaerobic tank 2, the first MBBR aerobic tank 3, the second MBBR aerobic tank 4, the first anoxic tank 5, the second anoxic tank 6, the secondary sedimentation tank 1, and the filter tank 7 are connected in sequence.

[0045] Secondary sedimentation tank 1 is a regular hexagon. Anaerobic tank 2, first MBBR aerobic tank 3, second MBBR aerobic tank 4, first anoxic tank 5, second anoxic tank 6, and filtration tank 7 are all irregular hexagons. Any two adjacent tanks in secondary sedimentation tank 1, anaerobic tank 2, first MBBR aerobic tank 3, second MBBR aerobic tank 4, first anoxic tank 5, second anoxic tank 6, and filtration tank 7 share a common edge. Secondary sedimentation tank 1, anaerobic tank 2, first MBBR aerobic tank 3, second MBBR aerobic tank 4, first anoxic tank 5, second anoxic tank 6, and filtration tank 7 form an irregular honeycomb shape. The volume of anaerobic tank 2, first MBBR aerobic tank 3, second MBBR aerobic tank 4, first anoxic tank 5, second anoxic tank 6, and filtration tank 7 is smaller than the volume of secondary sedimentation tank 1. The volumes of anaerobic tank 2, first MBBR aerobic tank 3, second MBBR aerobic tank 4, first anoxic tank 5, second anoxic tank 6, and filtration tank 7 are the same.

[0046] The anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, the secondary sedimentation tank, and the filtration tank are combined into a special-shaped honeycomb shape of "large inside and small outside", which meets the flexible redundancy of the high solid load of the secondary sedimentation tank in the AOA process. While ensuring a higher total amount of microbial flora and sludge concentration carried by the system, it significantly reduces the risk of the sludge interface rising or even mud turning in the secondary sedimentation tank, increases a certain error tolerance rate, and enables the AOA process to operate more stably.

[0047] A number of spherical combined suspended fillers are installed in both the first MBBR aerobic tank 3 and the second MBBR aerobic tank 4. The combined suspended filler 20 includes a hollow filler ball 2001 and a polyurethane sponge filler block 2002. Each hollow filler ball 2001 contains 6 - 10 polyurethane sponge filler blocks 2002, and the length, width, and height of the polyurethane sponge filler block 2002 are 15 - 20 mm × 15 - 20 mm × 15 - 20 mm.

[0048] The aerator aerates the first MBBR aerobic tank and the second MBBR aerobic tank to promote the normal fluidization of the combined suspended filler, and promotes the free and smooth rotation of the combined suspended filler in the sewage, increasing the impact and cutting of the bubbles in the sewage. Moreover, the water flow and bubbles can pass through the inside of the combined suspended filler, strengthening the shedding and renewal of the aged biofilm and maintaining the activity of the biofilm.

[0049] An anaerobic tank, a first MBBR aerobic tank, a second MBBR aerobic tank, a first anoxic tank, a second anoxic tank, a secondary sedimentation tank, and a filtration tank are set up to be connected in sequence, and combined suspended fillers are installed in the first MBBR aerobic tank and the second MBBR aerobic tank respectively. The MBBR process is coupled with the AOA process to form the AOA - MBBR process. Since both mud and film coexist on the combined suspended filler, the advantage of the biofilm in enriching nitrifying bacteria is prominent. The relative abundance of nitrifying bacteria on the combined suspended carrier is generally about 10%, which is much higher than the proportion of nitrifying bacteria in the activated sludge. Therefore, the AOA - MBBR mud - film composite process has higher sewage treatment efficiency and stronger environmental stress resistance. The sewage is treated through the alternating states of anaerobic, aerobic (MBBR), and anoxic, improving the biological treatment of the total nitrogen and total phosphorus removal rate, and maximizing the utilization of the raw water organic matter and internal carbon source to achieve the purpose of strengthening biological nitrogen and phosphorus removal.

[0050] A cylindrical screen 12 for intercepting the combined suspended filler is installed at the water outlet of the first MBBR aerobic tank 3 and the second MBBR aerobic tank 4. The cylindrical screen 12 includes a circular stainless - steel ring 1201 and N "丿"-shaped stainless - steel rods

[0051] Both the first MBBR aerobic tank 3 and the second MBBR aerobic tank 4 are equipped with float level gauges 14 and aerators 11. The float level gauges monitor the liquid levels in the first and second MBBR aerobic tanks. If the liquid levels in the first and second MBBR aerobic tanks rise abnormally, feedback is sent to the control cabinet, thereby controlling the first electrically controlled valve to reduce the amount of sewage flowing into the anaerobic tank and prevent the risk of flooding in the first and second MBBR aerobic tanks.

[0052] The second MBBR aerobic tank 4 is equipped with an online dissolved oxygen meter 16 and an online ammonia nitrogen monitor 17.

[0053] Each of the float level gauge 14, the online dissolved oxygen meter 16, and the online ammonia nitrogen monitor 17 is covered by a protective cover 15. The protective cover 15 includes a C-shaped protective cover plate 1501 and two L-shaped mounting plates 1502. The two mounting plates 1502 are respectively fixed to the top two sides of the protective cover plate 1501. The opening width of the protective cover plate 1501 is smaller than the diameter of the combined suspended packing 20. A water passage hole 1503 is opened at the top of the protective cover plate 1501. The height of the water passage hole 1503 is smaller than the diameter of the combined suspended packing 20.

[0054] A protective cover is placed over the float level gauge to prevent the combined suspended packing from accumulating around the float level gauge, causing accidental contact and generating incorrect level monitoring data.

[0055] A first electrically controlled valve 8 is installed at the inlet of anaerobic tank 2 to control the flow rate of sewage. A first sludge return pipe 9 with a second electrically controlled valve 10 is installed between secondary sedimentation tank 1 and anaerobic tank 2. A second sludge return pipe 18 with a third electrically controlled valve 19 is installed between secondary sedimentation tank 1 and first anoxic tank 5. A sludge pump 21 is installed in secondary sedimentation tank 1. A sludge discharge pipe 22 is also installed on secondary sedimentation tank 1 to discharge excess sludge. The outlet of the sludge pump is connected to the first sludge return pipe, the second sludge return pipe, and the sludge discharge pipe, respectively.

[0056] The inlet end of the aerator 11 is connected to an aeration blower via a pipe. In the first MBBR aerobic tank 3 and the second MBBR aerobic tank 4, a backwash pipe 13 is installed below the cylindrical screen 12 to prevent the accumulation of the combined suspended packing 20. The inlet end of the backwash pipe is connected to the air outlet of the aeration blower via a pipe.

[0057] The control cabinet is connected to the float level gauge 14, the online dissolved oxygen meter 16, the online ammonia nitrogen monitor 17, the aeration blower, the first electrically controlled valve 8, the second electrically controlled valve 10, the third electrically controlled valve 19, and the sludge pump via cables.

[0058] This technical solution utilizes an online dissolved oxygen meter 16 and an online ammonia nitrogen monitor 17 to monitor the dissolved oxygen and ammonia nitrogen content of the wastewater in the second MBBR aerobic tank 4, respectively. The monitoring data is fed back to the control cabinet, which controls the air volume of the aeration blower to adapt the aeration volume of the aerator to the changes in the influent volume and water quality.

[0059] A fine screen is installed at the inlet of anaerobic tank 2 to filter out debris from the wastewater. A 3-5mm fine screen is installed in the pretreatment unit to minimize the amount of debris carried by the wastewater into the system.

[0060] To facilitate the sending of flood signals by relevant management personnel, the float level gauge 14 is equipped with a full network 4G module with a SIM card slot, which can be used to send level alarm information to the mobile terminal carried by the staff.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A wastewater treatment system for enhancing the stable operation of the AOA-MBBR process, characterized in that: It includes a control cabinet and a hexagonal secondary sedimentation tank. An anaerobic tank, a first MBBR aerobic tank, a second MBBR aerobic tank, a first anoxic tank, a second anoxic tank, and a filtration tank in the shape of a hexagon are sequentially arranged around the secondary sedimentation tank. The anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, the secondary sedimentation tank, and the filtration tank are sequentially connected. The secondary sedimentation tank is a regular hexagon, and the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank are all irregular hexagons. The secondary sedimentation tank, the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank form an irregular honeycomb shape. A number of spherical combined suspended fillers are installed in the first MBBR aerobic tank and the second MBBR aerobic tank. The combined suspended filler includes a hollow filler ball and a polyurethane sponge filler block. Each hollow filler ball contains 6 - 10 polyurethane sponge filler blocks. The length, width, and height of the polyurethane sponge filler block are 15 - 20 mm × 15 - 20 mm × 15 - 20 mm. At the outlet of the first MBBR aerobic tank and the second MBBR aerobic tank, a cylindrical screen for intercepting the combined suspended filler is installed. The cylindrical screen includes a circular stainless - steel ring and N "丿"-shaped stainless - steel rods. The tail ends of the stainless - steel rods are welded to the stainless - steel ring. The N stainless - steel rods are arranged in a circular array on the stainless - steel ring, and the distance between any two adjacent stainless - steel rods is less than the diameter of the combined suspended filler. Float level gauges and aerators are installed in both the first MBBR aerobic tank and the second MBBR aerobic tank. An on - line dissolved oxygen meter and an ammonia - nitrogen on - line monitor are installed in the second MBBR aerobic tank. A protective cover is respectively sleeved outside the float level gauge, the on - line dissolved oxygen meter, and the ammonia - nitrogen on - line monitor. The inlet end of the aerator is connected to an aeration blower through a pipeline. The protective cover includes a protective cover plate with a C - shaped cross - section and two L - shaped mounting plates. The two mounting plates are respectively fixed on both sides of the top of the protective cover plate. The opening width of the protective cover plate is less than the diameter of the combined suspended filler. A first electric control valve for controlling the inflow rate of sewage is installed at the inlet of the anaerobic tank. A first sludge return pipe with a second electric control valve is installed between the secondary sedimentation tank and the anaerobic tank. A second sludge return pipe with a third electric control valve is installed between the secondary sedimentation tank and the first anoxic tank. The control cabinet is respectively connected to the float level gauge, the on - line dissolved oxygen meter, the ammonia - nitrogen on - line monitor, the aeration blower, the first electric control valve, the second electric control valve, and the third electric control valve by cables.

2. The wastewater treatment system according to claim 1, characterized in that: Any two adjacent tank bodies among the secondary sedimentation tank, the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank have a common side.

3. The wastewater treatment system according to claim 1, characterized in that: The volumes of the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank are all smaller than the volume of the secondary sedimentation tank, while the volumes of the anaerobic tank, the first MBBR aerobic tank, the second MBBR aerobic tank, the first anoxic tank, the second anoxic tank, and the filtration tank are the same.

4. The wastewater treatment system according to claim 1, characterized in that: The anaerobic tank is equipped with a fine screen at the inlet to filter out debris from the wastewater.

5. The wastewater treatment system according to claim 1, characterized in that: The secondary sedimentation tank is equipped with a sludge pump and a sludge discharge pipe for discharging excess sludge. The outlet of the sludge pump is connected to the first sludge return pipe, the second sludge return pipe, and the sludge discharge pipe, respectively. The sludge pump is connected to the control cabinet by a cable.

6. The wastewater treatment system according to claim 1, characterized in that: The upper part of the protective cover plate has a water passage hole, and the height of the water passage hole is smaller than the diameter of the combined suspended packing.

7. The wastewater treatment system according to claim 1, characterized in that: In the first MBBR aerobic tank and the second MBBR aerobic tank, a backwash pipe is installed below the cylindrical screen to prevent the accumulation of combined suspended packing. The inlet end of the backwash pipe is connected to the outlet of the aeration blower through a pipe.

8. The wastewater treatment system according to claim 1, characterized in that: The float level gauge is equipped with a full network compatible 4G module with a SIM card slot.

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