Microaerophilic biofilm reactor

Abstract

The application discloses a micro-aerobic biofilm reactor and relates to the technical field of rural domestic sewage treatment. The shell is sequentially divided into an anaerobic pool, a micro-aerobic pool and a sedimentation and clarification pool in the shell; anaerobic biofilm fillers are vertically arranged at equal distances in the anaerobic pool; and biofilm combined filler bundles are hung in the micro-aerobic pool. The anaerobic pool and the micro-aerobic pool are combined in series, a biochemical environment with a dissolved oxygen gradient distribution is constructed, the synergistic effect of short-cut nitrification and denitrification and anaerobic ammonia oxidation is realized, and the technical problems of insufficient carbon source and low denitrification efficiency of low C / N ratio rural domestic sewage are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of rural domestic sewage treatment technology, specifically to a micro-aerobic biofilm reactor. Background Technology

[0002] With the widespread availability of tap water in rural areas and the advancement of the "toilet revolution," per capita domestic water consumption and sewage discharge in rural areas have increased significantly, making rural domestic sewage a pressing issue in rural environmental improvement. Since 2000, the country has gradually emphasized rural living environment improvement. From 2013 to 2021, the country invested over 160 billion yuan in rural domestic sewage treatment, resulting in a significant increase in my country's rural sewage treatment rate, reaching 31% in 2022. However, the C / N ratio of rural domestic sewage is typically low, and many sewage treatment facilities fail to meet effluent standards for nitrogen and phosphorus. Furthermore, the discharge of nitrogen and phosphorus into surface water can easily lead to eutrophication, posing a potential threat to the natural environment and human health. Therefore, effectively reducing the concentration of nitrogen and phosphorus pollutants has become a key concern.

[0003] Traditional biological nitrogen removal primarily employs nitrification and denitrification processes, with dissolved oxygen (DO) and the carbon-to-nitrogen ratio (C / N) being crucial influencing factors. Denitrification requires an organic carbon source as an electron donor. However, rural domestic wastewater typically has a low C / N ratio, resulting in insufficient carbon sources for microbial metabolism and a lack of electron donors for denitrification, making complete nitrogen removal difficult. While adding additional carbon sources (including methanol, ethanol, acetic acid, and glucose) and increasing aeration can improve nitrogen removal efficiency, this significantly increases the economic cost of wastewater treatment and fails to achieve the goals of energy conservation and carbon emission reduction. Clearly, conventional nitrification / denitrification processes cannot meet the normal nitrogen removal requirements for low-carbon nitrification wastewater. Therefore, developing energy-efficient, high-efficiency, and sustainable pollutant removal technologies for rural domestic wastewater with low C / N ratios is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a micro aerobic biofilm reactor to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a microaerobic biofilm reactor, comprising a shell, wherein the shell is sequentially divided into an anaerobic tank, a microaerobic tank, and a sedimentation and clarification tank;

[0006] Anaerobic biofilm-attached packing materials are arranged vertically at equal intervals within the anaerobic tank;

[0007] The biofilm-attached composite packing material bundles are suspended inside the micro-aerobic tank;

[0008] An inlet pipe is installed on one side of the anaerobic tank of the shell, and the outlet of the inlet pipe is located at the bottom of the anaerobic tank.

[0009] The bottom of the biofilm-attached composite packing bundle is equipped with an aeration and liquid inlet device, which pumps the sewage from the top of the anaerobic tank and outside air into the bottom of the biofilm-attached composite packing bundle.

[0010] The micro-aerobic tank and the sedimentation and clarification tank are connected by a water pipe. The inlet and outlet of the water pipe are located at the top of the micro-aerobic tank and the bottom of the sedimentation and clarification tank, respectively. The sedimentation and clarification tank has an outlet at the top, and the height of the outlet is lower than the height of the inlet of the water pipe.

[0011] A sludge return pipe is installed between the anaerobic tank and the sedimentation and clarification tank. A sludge return pump is connected to the sludge return pipe located in the sedimentation and clarification tank. The sludge return pump is located on the side of the liquid outlet of the water pipe, and the liquid outlet of the sludge return pipe is located at the bottom of the anaerobic biofilm packing.

[0012] Preferably, the top of the shell is provided with at least three inspection ports, which are distributed on the top of the anaerobic tank, the micro-aerobic tank and the sedimentation and clarification tank.

[0013] Preferably, the biofilm-attached composite packing bundle includes a packing filter barrel, the top of which is provided with a movable hook, which is connected to a packing support fixed at the top of the micro-aerobic tank. The inside of the packing filter barrel is filled with polyurethane sponge packing, and the outside of the packing filter barrel is provided with a stainless steel support, on which the composite fiber biofilm-attached packing is hung.

[0014] Preferably, the anaerobic biofilm packing material is a combination packing material that combines soft packing material and semi-soft packing material, and is arranged vertically in the pool at equal intervals of 150mm×150mm.

[0015] Preferably, the anaerobic tank and the microaerobic tank are connected by the microaerobic tank inlet, and the height of the liquid inlet of the water pipe is lower than the height of the microaerobic tank inlet.

[0016] The aeration and liquid inlet device includes a drain pipe, which is connected to the inlet of the micro-aerobic tank, and a liquid pump is connected to the body of the drain pipe.

[0017] The bottom of the drain pipe is fixedly connected to a horizontal pipe, and several sets of aeration components are installed on the side of the horizontal pipe. Each set of aeration components consists of several aeration heads connected in series.

[0018] An aeration pipe is fixedly connected to the body of the drain pipe, and an aeration fan is connected to the body of the aeration pipe extending out of the shell.

[0019] A solenoid valve is connected to the body of the drain pipe.

[0020] Preferably, a gas-liquid static mixer is connected to the body of the drain pipe, and the aeration pipe is fixedly connected to the air inlet pipe of the gas-liquid static mixer.

[0021] Preferably, a bypass pipe is fixedly connected to the body of the drain pipe, and the inlet and outlet of the bypass pipe are located on both sides of the liquid pump, respectively.

[0022] A one-way valve is connected to the bypass pipe.

[0023] Preferably, the aeration head includes a connecting pipe and a shell, the connecting pipe penetrates the shell, and a plurality of first through holes are provided on the connecting pipe body located inside the shell;

[0024] The top of the outer shell has an arc-shaped slope, and the top of the outer shell has several second through holes that communicate with the inner cavity of the outer shell. The extension line of the central axis of the second through hole coincides with the center of the arc of the arc-shaped slope.

[0025] Each second through hole is fixed with a U-shaped bend at the top, with the outlet of the U-shaped bend facing downwards.

[0026] Preferably, the outer casing includes an upper shell and a bottom cover, which are movably screwed together.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This microaerobic biofilm reactor, through the series combination design of anaerobic and microaerobic tanks, constructs a biochemical environment with a dissolved oxygen gradient distribution, realizing the synergistic effect of short-cut nitrification and denitrification and anaerobic ammonia oxidation, effectively solving the technical problems of insufficient carbon source and low nitrogen removal efficiency in rural domestic sewage with low C / N ratio.

[0029] In addition, the liquid inlet device is located at the bottom of the micro-aerobic tank, so that the effluent from the anaerobic tank and air are fully mixed in the gas-liquid static mixer and then flow from bottom to top through the biofilm-attached composite packing bundle. During this process, the microbial metabolism consumes most of the dissolved oxygen in the water, so that the dissolved oxygen content in the liquid entering the sedimentation and clarification tank is maintained at an extremely low level. After this low-oxygen mud-water mixture is returned to the anaerobic tank through the mud-water return pipe, it will not destroy the strict anaerobic environment of the anaerobic tank. This effectively avoids the problem of inhibiting the activity of denitrifying bacteria due to excessive dissolved oxygen carried by the return liquid in the traditional process, and significantly improves the denitrification efficiency.

[0030] In addition, the top of the aeration head is equipped with an arc-shaped slope, and a U-shaped bend with the liquid outlet facing downward is fixed at the second through hole. This prevents the detached biofilm from adhering and accumulating on the surface of the aeration head, but instead allows it to slide down the arc-shaped slope to the bottom of the pool, thus solving the problem of aeration disc blockage caused by biofilm detachment.

[0031] Meanwhile, the aeration head works in conjunction with the gas-liquid static mixer to form micro-nano-scale bubbles with wastewater and air. These bubbles have the characteristics of large specific surface area, slow rising speed, long gas-liquid contact time, and high dissolution efficiency. They can be evenly dispersed and fully contact the packing bundle in three phases, penetrating deep into the pores inside the packing, improving oxygen mass transfer efficiency and utilization, reducing aeration energy consumption, and also promoting the stable attachment and growth of microbial films. Attached Figure Description

[0032] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0033] Figure 2 This is a schematic diagram of the biofilm-attached composite packing bundle structure of the present invention;

[0034] Figure 3 This is a structural diagram of the aeration and liquid inlet device of the present invention;

[0035] Figure 4 This is a front view of the aeration head of the present invention;

[0036] Figure 5 This is an exploded view of the aeration head of the present invention.

[0037] In the diagram: 1. Anaerobic tank; 2. Microaerobic tank; 3. Sedimentation and clarification tank; 4. Inspection port; 5. Shell; 6. Inlet pipe; 7. Anaerobic biofilm packing material; 8. Aeration and liquid inlet device; 801. Drainage pipe; 802. Liquid pump; 803. Horizontal pipe; 804. Aeration pipe; 805. Gas-liquid static mixer; 806. Aeration head; 8061. Connecting pipe; 8062. Shell; 8063. Bottom cover; 806 4. U-shaped bend; 807. Bypass pipe; 808. Check valve; 9. Micro aerobic tank inlet; 10. Packing support; 11. Biofilm-attached composite packing bundle; 12. Water passage pipe; 13. Sludge return pump; 14. Sludge return pipe; 15. Outlet; 111. Movable hook; 112. Packing filling filter barrel; 113. Polyurethane sponge packing; 114. Stainless steel support; 115. Composite fiber biofilm-attached packing. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figures 1-5As shown, the present invention provides a technical solution: a micro-aerobic biofilm reactor, which is mainly used for the treatment of domestic sewage or organic wastewater, especially for decentralized sewage treatment scenarios with high requirements for nitrogen and phosphorus removal efficiency.

[0040] like Figure 1 As shown, the reactor shell 5 is divided into an anaerobic tank 1, a microaerobic tank 2, and a sedimentation and clarification tank 3 by partitions. At least three inspection ports 4 are provided on the top of the shell 5, located directly above the top of each of the anaerobic tank 1, microaerobic tank 2, and sedimentation and clarification tank 3. The diameter of each inspection port 4 is preferably 600 mm, and each inspection port 4 is fitted with a maintenance cover. Operators can open the maintenance cover and use the inspection port 4 to inspect the equipment, replace the packing material, or perform cleaning and maintenance inside each tank, facilitating the long-term stable operation of the equipment. This microaerobic biofilm reactor has a compact overall structure, can be buried underground, occupies little space, does not affect ground planting, and has a wide range of applications.

[0041] On the side wall of the shell 5, corresponding to the position of the anaerobic tank 1, there is an inlet pipe 6. The inlet end of the inlet pipe 6 is connected to an external sewage source, and its outlet extends to the bottom of the anaerobic tank 1. Specifically, the inlet pipe 6 enters from the inspection port 4 near the upper end of the anaerobic tank 1 and extends vertically downward to the bottom of the anaerobic tank 1. This bottom-inlet method allows the incoming water flow to impact upward from the bottom, effectively preventing the deposition of mud film at the bottom of the tank and ensuring sufficient contact between the anaerobic biofilm packing material 7 filled in the upper reaction zone and the sewage. The packing material 7 is a combination packing material that combines the advantages of soft packing material and semi-soft packing material. Its specific structure is transformed from plastic discs to double-ring large plastic rings. The inner ring is made of snowflake-shaped plastic branches with fiber bundles evenly distributed on the ring. This structural design increases the specific surface area, which is conducive to the attachment and growth of microorganisms. The entire anaerobic biofilm packing material 7 is fixed in the anaerobic tank 1 with a spacing of 150mm×150mm and is arranged vertically at equal intervals to form a regular packing array, ensuring that the sewage can fully contact the microbial film on the packing material during the rising process.

[0042] like Figure 1 and Figure 2As shown, the anaerobic tank 1 and the microaerobic tank 2 are connected by the microaerobic tank inlet 9. Wastewater treated anaerobically enters the microaerobic tank 2 through the microaerobic tank inlet 9. Multiple biofilm-bearing composite packing bundles 11 are suspended inside the microaerobic tank 2. Each composite packing bundle 11 includes a packing filter 112. The top of the packing filter 112 is equipped with a movable hook 111, which connects to a packing support 10 fixed to the top of the microaerobic tank 2. This flexible hook design makes disassembly and maintenance of the packing extremely convenient; operators can directly remove the entire packing bundle for rinsing through the inspection port 4. Alternatively, it can be replaced, and it is also convenient to remove the packing material and then inspect the aeration system below. The inside of the packing filter barrel 112 is filled with polyurethane sponge packing material 113, which is wrapped with wire mesh or plastic mesh to prevent the polyurethane sponge packing material 113 from being dispersed by aeration. The outside of the packing filter barrel 112 is equipped with a stainless steel support 114, and the stainless steel support 114 is covered with combined fiber biofilm packing material 115. This combination of internal and external structure makes the entire packing bundle form different oxygen contact gradients from the inside to the outside, thereby enriching aerobic, anoxic, and anaerobic microbial communities, making them more diverse, more fully biofilm formed, and more effective in removing pollutants.

[0043] like Figure 1 , Figures 3-5 As shown, the bottom of the biofilm-attached composite packing bundle 11 is equipped with an aeration and liquid inlet device 8, which integrates water inlet and aeration functions. Specifically, it includes a drain pipe 801, the water inlet end of which is connected to the water inlet 9 of the micro-aerobic tank. A liquid pump 802 is connected to the body of the drain pipe 801 to pump the sewage from the top of the anaerobic tank 1 into the drain pipe 801. A horizontal pipe 803 is fixedly connected to the bottom of the drain pipe 801. The horizontal pipe 803 is horizontally arranged at the bottom of the micro-aerobic tank 2. Several sets of aeration components are arranged on the side of the horizontal pipe 803. Each set of aeration components consists of several aeration heads 806 connected in series and detachable. An aeration pipe 804 is also fixedly connected to the body of the drain pipe 801. The aeration pipe 804 extends out of the shell 5, and an aeration blower is connected to its exposed body to transport air.

[0044] like Figure 3As shown, a solenoid valve is also connected to the body of the drain pipe 801 to control the flow of water. To optimize the gas-liquid mixing effect, a gas-liquid static mixer 805 is also connected to the body of the drain pipe 801. The air outlet of the aeration pipe 804 is fixedly connected to the air inlet of the gas-liquid static mixer 805. In this way, after the sewage from the anaerobic tank 1 and the air from the aeration blower are mixed in the gas-liquid static mixer 805, the large bubbles are continuously sheared, collided, and broken into micro-nano-scale bubbles under the action of the unique spiral blades or cross baffle structure inside the static mixer. These micro-nano-scale bubbles have significant characteristics such as large specific surface area, slow rising speed, long gas-liquid contact time, and high dissolution efficiency, which greatly improves the mass transfer efficiency and utilization rate of oxygen. Compared with the large bubbles generated by traditional aeration methods, micro-nano-scale bubbles can be more evenly dispersed in the sewage and achieve more sufficient three-phase contact with the microbial film in the biofilm composite packing bundle 11, effectively reducing aeration energy consumption. At the same time, the small size of the micro-nano-scale bubbles enables them to... The bubbles can penetrate deep into the pores of the filter media 112 and polyurethane sponge packing 113, providing a suitable dissolved oxygen environment for aerobic and anoxic microorganisms inside the packing. This further enhances the simultaneous nitrification and denitrification processes, improving the overall nitrogen removal efficiency and pollutant removal capacity of the system. In addition, due to the fine and uniform bubbles, the physical impact on the packing bundles is small, which is conducive to the stable attachment and growth of the microbial film and avoids the problem of premature biofilm detachment caused by violent disturbance, thus ensuring the long-term stable operation of the system. Furthermore, during the rising of the bubbles, the microorganisms consume the dissolved oxygen in the water, thereby maintaining a low oxygen content in the liquid that finally enters the sedimentation and clarification tank 3. When this low-oxygen mud-water mixture is returned to the anaerobic tank 1 through the return pipe, it will not disrupt the anaerobic environment of the anaerobic tank 1. In addition, the generated micro- and nano-sized bubbles help promote the enrichment of ammonia-oxidizing bacteria, inhibit the growth of nitrite-oxidizing bacteria, promote short-cut nitrification, and significantly improve the nitrogen removal efficiency of denitrifying bacteria in the anaerobic tank 1.

[0045] In addition, a bypass pipe 807 is fixedly connected to the body of the drain pipe 801. The inlet and outlet of the bypass pipe 807 are located on both sides of the liquid pump 802. A one-way valve 808 is connected to the body of the bypass pipe 807. When forced circulation (when aeration is required) or backwashing is required, the liquid pump 802 can be turned on. At this time, the pressure on the side of the bypass pipe 807 near the outlet of the liquid pump 802 is greater than that on the side near the inlet. The one-way valve 808 is in the closed state. After being pressurized by the liquid pump 802, the liquid enters the bottom of the micro-aerobic tank 2. When the oxygen content of the micro-aerobic tank 2 is normal and no additional power is required, the liquid pump 802 can be turned off. At this time, the water will naturally flow through the bypass pipe 807 by utilizing the liquid level difference. The one-way valve 808 opens under the action of the water pressure at the inlet end, thereby achieving energy-saving operation and reducing operating energy consumption.

[0046] like Figure 5As shown, to prevent aeration head blockage caused by biofilm shedding, in this design, the aeration head 806 includes a connecting pipe 8061 and a shell 8062. The connecting pipe 8061 penetrates the shell 8062. Several first through holes are formed on the pipe body of the connecting pipe 8061 located inside the shell 8062. The top of the shell 8062 forms an arc-shaped slope. Several second through holes communicating with the inner cavity of the shell 8062 are formed on the top of the shell 8062, and the extension line of the central axis of the second through holes coincides with the center of the arc of the arc-shaped slope. Each second through hole has a U-shaped bend 8064 fixed at its top, with the liquid outlet of the U-shaped bend 8064 facing downwards. As a preferred assembly method, the outer shell 8062 includes an upper shell and a bottom cover 8063, which are movably screwed together for easy disassembly and cleaning. During operation, a gas-liquid mixture enters the connecting pipe 8061, while liquid-gas or liquid enters the inner cavity of the outer shell 8062 through the first through hole and then exits through the second through hole and the U-shaped bend 8064. This design facilitates airflow... Multiple, dispersed microbubbles are formed at the outlet, improving oxygen mass transfer efficiency. More importantly, the downward-facing outlet of the U-shaped bend 8064, combined with its curved slope, prevents detached biofilm from adhering and accumulating on the surface of the aeration head 806. Instead, it slides down the curved slope and eventually settles to the bottom of the tank, preventing the aeration head 806 from becoming clogged. Only periodic cleaning of the tank bottom is required, significantly reducing maintenance workload. Furthermore, to avoid excessive water resistance in gravity flow mode, the connecting pipe 80... The diameter of the first through hole on 61 is preferably 6-12mm, the diameter of the second through hole on the top of the outer shell 8062 is preferably 4-8mm, the inner diameter of the U-shaped bend 8064 is preferably 5-10mm, and the number of aeration heads 806 on each horizontal pipe 803 is not less than 3, so that the total cross-sectional area of ​​all aeration heads is not less than twice the cross-sectional area of ​​the inlet pipe 6. According to hydraulic calculations, under the drive of a liquid level difference of 0.3m, this design can meet the gravity flow of water at the maximum design flow rate and will not cause water stagnation at the front end.

[0047] like Figure 1As shown, the microaerobic tank 2 and the sedimentation and clarification tank 3 are connected by a water pipe 12. The inlet of the water pipe 12 is located at the top of the microaerobic tank 2, and its outlet extends to the bottom of the sedimentation and clarification tank 3. This top-in, bottom-out water flow method means that the wastewater in the microaerobic tank 2 must first flow upward through the packing bundle, and then enter the water pipe 12 from the top, thus extending the water flow path. The hydraulic elevation design of the entire reactor follows the principle of gravity flow. Specifically, the heights of the outlet of the inlet pipe 6, the inlet 9 of the microaerobic tank, the inlet and outlet of the water pipe 12, and the outlet 15 of the sedimentation and clarification tank 3 decrease sequentially. That is, the outlet of the inlet pipe 6 is located at the bottom (lowest) of the anaerobic tank 1, the inlet 9 of the microaerobic tank is located at the top of the anaerobic tank 1 (higher than the outlet of the inlet pipe 6), the inlet of the water pipe 12 is located at the top of the microaerobic tank 2 (lower than the inlet 9 of the microaerobic tank), and the outlet of the water pipe 12... The outlet of 2 is located at the bottom of the sedimentation and clarification tank 3 (lower than the inlet of the water pipe 12), while the outlet 15 is located at the top of the sedimentation and clarification tank 3 (higher than the outlet of the water pipe 12 but lower than the inlet of the water pipe 12). This staggered elevation design ensures smooth water flow and allows for gravity flow without additional power. In addition, in the three compartments of the entire device—anaerobic tank 1, microaerobic tank 2, and sedimentation and clarification tank 3—the water flow direction is arranged alternately vertically and horizontally, resulting in a "Z"-shaped flow in the horizontal direction. This layout makes the wastewater flow path longer and allows for full contact with the packing material, microorganisms, and oxygen in the reactor. At the same time, the design of the inlet and outlet at different heights effectively avoids short-circuiting of wastewater, reduces dead zones in the reactor, further extends the wastewater flow path, and improves the removal efficiency of pollutants.

[0048] Near the outlet of the water inlet pipe 12 in the sedimentation and clarification tank 3, a mud-water return pump 13 is installed. The mud-water mixture is pumped back to the anaerobic tank 1 via the mud-water return pipe 14. The inlet of the mud-water return pipe 14 is also located at the bottom of the anaerobic biofilm packing 7. The return ratio can be adjusted between 50% and 100% according to the actual water quality. In this embodiment, 100% is preferred. Through this return system, the nitrite and nitrate nitrogen produced in the nitrification process in the microaerobic tank 2 are returned to the front anaerobic tank 1. In the anaerobic tank 1, denitrifying bacteria use the organic carbon source in the influent to reduce these nitrogen oxides into nitrogen gas, which then escapes, thus completing the process. In the denitrification process, since this device mainly adopts the biofilm process and controls the dissolved oxygen concentration in the micro-aerobic tank 2 to be low, the amount of residual sludge produced is extremely low. More importantly, this system only needs to set up one return pipeline to realize the return of sludge and digestate at the same time, saving the dedicated sludge return pipeline and simplifying the system structure. In particular, due to the design of the aforementioned aeration and liquid inlet device 8, the dissolved oxygen concentration of the liquid entering the sedimentation and clarification tank 3 is already very low. Therefore, the dissolved oxygen concentration of the nitrified liquid returned by the sludge return pump 13 is also very low. This further ensures the strict anaerobic environment in the anaerobic tank 1, providing favorable conditions for efficient denitrification.

[0049] This embodiment controls the dissolved oxygen concentration in the micro-aerobic tank 2 to maintain it below 1.0 mg / L, preferably 0.3-0.8 mg / L. Under this low-oxygen environment, the activity of nitrite-producing bacteria in the micro-aerobic reaction system is dominant, promoting the accumulation of nitrite nitrogen while limiting the further oxidation of nitrite nitrogen to nitrate nitrogen. This not only reduces the energy consumption of aerobic aeration but also reduces the carbon source required for subsequent denitrification, achieving short-cut nitrification and denitrification and reducing operation and maintenance costs. To achieve precise control of dissolved oxygen concentration, the system can select between manual or automatic aeration control modes depending on the site environment and conditions. In manual adjustment mode, the operator manually adjusts the blower volume or the rotation speed of the aeration equipment based on the reading of the dissolved oxygen meter. For example, when the dissolved oxygen concentration is found to be below 1 mg / L, the blower volume or rotation speed of the aeration equipment can be adjusted accordingly. Increase the frequency of the blower by 5%-10% each time, and continuously monitor the changes in dissolved oxygen until it returns to the target range. In automatic control mode, install an online dissolved oxygen sensor in the middle of the micro-aerobic tank 2. The sensor should be calibrated every 1-2 weeks to ensure data accuracy. Connect the dissolved oxygen sensor to the controller of the aeration equipment and implement closed-loop control through automatic control algorithms such as PID controller. When the dissolved oxygen concentration is lower than the set lower limit, the system automatically increases the output power of the aeration equipment. When the dissolved oxygen concentration is higher than the set upper limit, the system automatically reduces the output power. The controller precisely controls the operation of the aeration equipment based on the real-time deviation of dissolved oxygen to ensure the stability of the micro-aerobic environment.

[0050] Working principle: Domestic sewage is connected to the inlet pipe 6 through the water supply pipe and enters the bottom of the anaerobic tank 1. The sewage flows upward and comes into contact with the anaerobic biofilm packing material 7 to carry out hydrolysis, acidification, and denitrification reactions. At the same time, the return sludge from the sedimentation and clarification tank 3 enters from the bottom and uses the organic matter in the influent for denitrification. The effluent from the anaerobic tank 1 enters the aeration and liquid inlet device 8 through the micro-aerobic tank inlet 9. Under the transportation of the liquid pump 802, it is mixed with the air provided by the aeration blower in the gas-liquid static mixer 8. The mixture is mixed in 05 and then released to the bottom of the micro-aerobic tank 2 through horizontal pipe 803 and aeration head 806. The mixed liquid flows upward, passing through the biofilm composite packing bundle 11. Under low dissolved oxygen conditions, the microorganisms on the packing convert ammonia nitrogen into nitrite nitrogen. The effluent from the micro-aerobic tank 2 enters the water passage pipe 12 from its top through the inlet pipe, and then enters the bottom of the sedimentation and clarification tank 3 from the outlet of the water passage pipe 12. In the sedimentation and clarification tank 3, the mud and water are separated, and the supernatant is discharged from the top outlet 15 after meeting the standards. The settled mud and water mixture is pumped back to the bottom of the anaerobic tank 1 through the mud and water return pipe 14 by the mud and water return pump 13 for the next cycle of denitrification.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A micro aerobic biofilm reactor, comprising a shell (5), characterized in that: The shell (5) is divided into an anaerobic tank (1), a microaerobic tank (2), and a sedimentation and clarification tank (3) in sequence. Anaerobic biofilm packing material (7) is arranged vertically at equal intervals in the anaerobic tank (1); The biofilm-attached composite packing bundle (11) is suspended inside the microaerobic tank (2); An inlet pipe (6) is installed on one side of the anaerobic tank (1) of the shell (5), and the outlet of the inlet pipe (6) is located at the bottom of the anaerobic tank (1). The bottom of the biofilm combined packing bundle (11) is equipped with an aeration and liquid inlet device (8). The sewage from the top of the anaerobic tank (1) and the outside air are pumped into the bottom of the biofilm combined packing bundle (11) through the aeration and liquid inlet device (8). The micro-aerobic tank (2) and the sedimentation and clarification tank (3) are connected by a water pipe (12). The inlet and outlet of the water pipe (12) are located at the top of the micro-aerobic tank (2) and the bottom of the sedimentation and clarification tank (3), respectively. The sedimentation and clarification tank (3) has an outlet (15) at the top, and the height of the outlet (15) is lower than the height of the inlet of the water pipe (12). A mud-water return pipe (14) is installed between the anaerobic tank (1) and the sedimentation and clarification tank (3). A mud-water return pump (13) is connected to the mud-water return pipe (14) located in the sedimentation and clarification tank (3). The mud-water return pump (13) is located on the side of the outlet of the water pipe (12), and the outlet of the mud-water return pipe (14) is located at the bottom of the anaerobic biofilm packing (7).

2. The microaerobic biofilm reactor according to claim 1, characterized in that: The top of the shell (5) is provided with at least three inspection ports (4), which are distributed on the top of the anaerobic tank (1), the micro-aerobic tank (2) and the sedimentation and clarification tank (3).

3. The microaerobic biofilm reactor according to claim 1, characterized in that: The biofilm-attached composite packing bundle (11) includes a packing filter barrel (112), with a movable hook (111) on the top of the packing filter barrel (112). The movable hook (111) is connected to a packing support (10) fixed on the top of the micro-aerobic tank (2). The packing filter barrel (112) is filled with polyurethane sponge packing (113), and a stainless steel support (114) is provided on the outside of the packing filter barrel (112). A composite fiber biofilm-attached packing (115) is hung on the stainless steel support (114).

4. The microaerobic biofilm reactor according to claim 1, characterized in that: The anaerobic biofilm packing material (7) is a combination packing material that combines soft packing material and semi-soft packing material, and is arranged vertically in the pool at equal intervals of 150mm×150mm.

5. The microaerobic biofilm reactor according to claim 1, characterized in that: The anaerobic tank (1) and the microaerobic tank (2) are connected by the microaerobic tank inlet (9), and the height of the inlet of the water pipe (12) is lower than the height of the microaerobic tank inlet (9); The aeration and liquid inlet device (8) includes a drain pipe (801), which is connected to the inlet (9) of the micro-aerobic tank. A liquid pump (802) is connected to the body of the drain pipe (801). The bottom of the drain pipe (801) is fixedly connected to a horizontal pipe (803). Several sets of aeration components are provided on the side of the horizontal pipe (803). Each set of aeration components consists of several aeration heads (806) connected in series. An aeration pipe (804) is fixedly connected to the body of the drain pipe (801), and an aeration fan is connected to the body of the aeration pipe (804) extending out of the shell (5). A solenoid valve is connected to the body of the drain pipe (801).

6. The microaerobic biofilm reactor according to claim 5, characterized in that: The drain pipe (801) is connected to a gas-liquid static mixer (805), and the aeration pipe (804) is fixedly connected to the air inlet pipe of the gas-liquid static mixer (805).

7. The microaerobic biofilm reactor according to claim 5, characterized in that: A bypass pipe (807) is fixedly connected to the body of the drain pipe (801), and the inlet and outlet of the bypass pipe (807) are located on both sides of the liquid pump (802). A one-way valve (808) is connected to the body of the bypass pipe (807).

8. The microaerobic biofilm reactor according to claim 5, characterized in that: The aeration head (806) includes a connecting pipe (8061) and a shell (8062). The connecting pipe (8061) penetrates the shell (8062). The connecting pipe (8061) located inside the shell (8062) has several first through holes on its body. The top of the outer shell (8062) is formed with an arc-shaped slope, and the top of the outer shell (8062) is provided with several second through holes that are connected to the inner cavity of the outer shell (8062). The extension line of the central axis of the second through hole coincides with the center of the arc of the arc-shaped slope. Each second through hole is fixed with a U-shaped bend (8064) at the top, with the outlet of the U-shaped bend (8064) facing downwards.

9. The microaerobic biofilm reactor according to claim 8, characterized in that: The outer casing (8062) includes an upper shell and a bottom cover (8063), which are movably screwed together.

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