A drum-type biological filter suitable for factory aquaculture wastewater

Abstract

This invention provides a drum-type biological filter suitable for industrialized aquaculture wastewater treatment, comprising a control box, a drive unit, and a main body. The main body contains biological packing balls for microbial attachment. The main body includes an inlet, a rotating shaft, an outlet, a sludge discharge outlet, stirring ribs, bearings, and seals. The rotating shaft runs axially through the main body and is rotatably connected to it via bearings and seals. Multiple stirring ribs are evenly distributed circumferentially along the rotating shaft to stir the water and biological packing balls inside the main body, ensuring synchronous movement. The drive unit is electrically connected to the rotating shaft to drive its rotation. The control box is electrically connected to the drive unit to control its rotational speed. This invention features low energy consumption, stable operation, compact structure, convenient maintenance, portability, and easy series connection, making it suitable for treating industrialized recirculating aquaculture wastewater.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, and in particular relates to a drum-type biological filter suitable for wastewater from factory-scale aquaculture. Background Technology

[0002] Biofilters in aquaculture are the core water purification unit in recirculating aquaculture systems (RAS). This technology originated from biofilm methods in wastewater treatment and has developed alongside the transformation of aquaculture from extensive to intensive farming. Its core principle is to utilize microbial biofilms to degrade ammonia nitrogen, nitrite, and organic matter in the water, achieving water recycling. Currently, rotating biological discs are electrically powered and do not use aeration. Nitrification is achieved through alternating contact between the disc and wastewater and air. However, issues such as disc clogging and thick biofilms limit their development. On the other hand, moving bed biofilm reactors (MBBRs) are characterized by strong resistance to shock loads, low head loss, non-clogging, and no need for backwashing. However, their aeration energy consumption is high, and their external structure is usually made of cement, making them immobile and limiting their application scenarios. These limitations make it difficult for existing biofilters to simultaneously meet the requirements of low energy consumption, high stability, and flexible deployment in actual production. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a drum-type biological filter suitable for industrialized aquaculture wastewater, combining the advantages of biological rotating discs and MBBR, featuring low energy consumption, stable operation, compact structure, and convenient maintenance.

[0004] Note that the description of these objectives does not preclude the existence of other objectives. One aspect of the invention does not require achieving all of the above objectives. Objectives other than those described above can be extracted from the description, drawings, and claims.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] This invention combines the aeration-free drive of a biological rotating disc with the fluidization characteristics of MBBR packing material. Through internal stirring ribs, it drives the water and biological packing balls to move synchronously. While avoiding disc clogging and excessive biofilm thickness, it significantly reduces energy consumption and achieves equipment mobility and flexible multi-level control. Thus, it achieves the goals of stable operation, convenient maintenance, and series connection to increase the treated water volume.

[0007] A drum-type biological filter suitable for industrialized aquaculture wastewater includes a control box, a drive unit, and a main body of the device;

[0008] The main body of the device contains biological packing balls for the attachment of microorganisms;

[0009] The main body of the device includes an inlet, a rotating shaft, an outlet, a sludge discharge port, stirring ribs, bearings, and seals. The inlet and outlet are respectively located on the side walls of the main body, and the sludge discharge port is located at the bottom of the main body. The bearings and seals are located at both ends of the main body. The rotating shaft runs through the main body along its axial direction and is rotatably connected to the main body through the bearings and seals. There are multiple stirring ribs, evenly distributed around the rotating shaft, used to stir the water and biological packing balls inside the main body, so that the water and biological packing balls move synchronously.

[0010] The drive device is connected to the rotating shaft for driving the rotating shaft to rotate;

[0011] The control box is electrically connected to the drive unit and is used to control the speed of the drive unit.

[0012] In the above scheme, there are four stirring ribs, which are evenly distributed at 90° intervals along the circumference of the rotating shaft.

[0013] Furthermore, the stirring rib has a thickness of 5mm, a top length L of 740mm, a top-to-bottom distance W of 386mm, and a rectangular through hole with dimensions of 95mm × 680mm × 5mm is excavated in the middle of the bottom, the through hole extending through the thickness direction of the stirring rib.

[0014] Furthermore, the bottom sides of the four stirring ribs are respectively mounted on perforated bushings, and reinforcing discs are provided on both sides of the stirring ribs. The reinforcing discs are mounted on the perforated bushings, which are mounted on the rotating shaft, and the perforated bushings and the rotating shaft are fixedly connected by bolts. The top of one side of the rotating shaft is threaded and fitted with a shaft end retaining ring and a locking nut for axial positioning of the rotating shaft. The inner diameter of the reinforcing disc is 30mm and the outer diameter is 400mm. Two reinforcing discs are fixedly connected to both sides of the four stirring ribs.

[0015] Furthermore, the drive device includes a variable frequency motor and a worm gear reducer; the variable frequency motor is connected to the worm gear reducer, and the worm gear reducer is connected to the rotating shaft; the control box includes a frequency converter, which is electrically connected to the variable frequency motor and is used to control the speed of the variable frequency motor.

[0016] The above solution also includes a bottom bracket; the main body of the device is mounted on the bottom bracket, and casters are installed at the bottom of the bottom bracket.

[0017] Furthermore, there are two bottom supports, symmetrically installed below the main body of the device; each bottom support includes a bottom support plate, an arc-shaped bottom support plate, a side support plate, a circular arc support plate, and a circular arc side support plate; the arc-shaped bottom support plate, the side support plate, and the circular arc support plate are installed above the bottom support plate; the circular arc side support plate connects the side support plate and the circular arc support plate, and is also connected to the main body of the device; four composite casters are installed on the bottom support plate through openings, and the composite casters are omnidirectional adjustable casters.

[0018] In the above scheme, the lower part of the main body shell of the device is a cylindrical structure, including a first circular side plate on the left, a second circular side plate on the right, and a bent plate connecting the two; the upper part of the shell is a rectangular structure, including two oppositely arranged first upper side plates and two oppositely arranged second upper side plates, which together form a rectangular frame.

[0019] Furthermore, the water inlet is installed on the first circular side plate, and the center of the water inlet is 50mm away from the bottom of the main body of the device; there are four water outlets, which are installed at different heights on the second circular side plate, so that the water outlet level corresponds to 1 / 3, 1 / 2, 2 / 3 and 5 / 6 of the internal volume of the main body of the device; the sludge discharge port is installed at the bottom of the second circular side plate.

[0020] In the above scheme, the control box also includes a circuit breaker and a fuse for circuit protection.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention employs a drive device to synchronously rotate multiple stirring ribs on a rotating shaft, causing the water and biological packing balls within the main body of the device to move synchronously, achieving efficient oxygenation and hydraulic mixing under aeration-free conditions. Through CFD simulation optimization and experimental verification, at a rotation speed of 4 r / min and an immersion ratio of 2 / 3, the average flow field velocity stabilizes at 0.18–0.20 m / s, the packing is uniformly suspended, the dead zone ratio is less than 5%, and the turbulent kinetic energy is moderate, effectively avoiding packing deposition and localized dead zones. At 25±1℃, the steady-state dissolved oxygen concentration can reach 6.19 mg / L, far exceeding the dissolved oxygen level of traditional MBBRs under the same energy consumption.

[0023] 2. This invention replaces the discs of a traditional bio-disk with multiple stirring ribs (preferably four, distributed at 90° intervals around the perimeter), and sets a hollowed-out area (preferably a rectangular through-hole of 95mm × 680mm) in the middle of the bottom of the stirring ribs. Combined with a reinforcing disc, this significantly reduces rotational resistance, improves flow field uniformity, and helps avoid disc clogging and excessive biofilm thickness. Simulation results show that the average flow velocity of this stirring rib configuration (386-100mm) is 0.27–0.31 m / s, the turbulent kinetic energy is in the high range of 0.0191–0.0307 m² / s², the packing material is uniformly distributed, and the overall mass transfer performance is optimal.

[0024] 3. This invention uses a frequency converter to control the speed of the drive device, achieving stepless speed regulation to meet the differentiated speed requirements of different operating stages. Experimental data shows that, under a 4 r / min operating condition, when the system treats synthetic aquaculture wastewater (ammonia nitrogen concentration 10 mg / L, hydraulic retention time 24 h), the effluent ammonia nitrogen concentration remains stable below 0.02 mg / L, with an ammonia nitrogen removal rate approaching 100%. The effluent nitrite nitrogen concentration is below 0.03 mg / L, and nitrate nitrogen remains at a high and stable value of 11.0–11.5 mg / L, achieving complete nitrification. Daily power consumption is only about 3.6 kWh / d, significantly reducing operating energy consumption compared to traditional MBBR aeration processes.

[0025] 4. This invention features bearings and seals at both ends of the main body of the device, with a rotating shaft running through and rotatably connected, resulting in a compact structure and reliable sealing. ANSYS static simulation verification shows that the maximum equivalent stress of the stirring ribs is 6.16 MPa, the maximum equivalent stress of the bottom support is 19.07 MPa, and the combined bending and torsional stress of the rotating shaft is 0.19 MPa, all significantly lower than the allowable stress of 304 stainless steel (137 MPa). The overall structure is safe and reliable, with good long-term operational stability.

[0026] 5. The present invention features an inlet and multiple outlets on the side wall of the main body of the device (preferably four outlets corresponding to 1 / 3, 1 / 2, 2 / 3, and 5 / 6 of the internal volume, respectively), with the sludge discharge outlet located at the bottom. The inlet being 50mm from the bottom allows for a gentler inflow and increases the hydraulic retention time; multiple outlets at different heights allow for selection of the treatment water level as needed, flexibly adapting to different water quality conditions and treatment requirements.

[0027] 6. The bottom support of this invention is equipped with casters (preferably universal adjustable composite casters), which allows the equipment to move freely and level quickly, facilitating on-site deployment and series combination to expand processing capacity, overcoming the disadvantage of traditional MBBR cement structures being unable to move.

[0028] Note that the description of these effects does not preclude the existence of other effects. One aspect of the invention does not necessarily have to have all of the above.

[0029] The effects described above are obvious from the description, drawings, claims, etc. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a drum-type biological filter structure suitable for industrialized aquaculture wastewater according to one embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the control box according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the left side of the device body according to one embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of the right side of the device body according to an embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the interior of the device body according to one embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of a perforated bushing structure according to an embodiment of the present invention.

[0036] Figure 7 This is a schematic diagram of the stirring rib structure according to one embodiment of the present invention.

[0037] Figure 8 This is a schematic diagram of the internal structure of the left flange according to one embodiment of the present invention.

[0038] Figure 9 This is a schematic diagram of the internal structure of the right flange according to an embodiment of the present invention.

[0039] Figure 10 This is a schematic diagram of the rotating shaft structure according to one embodiment of the present invention.

[0040] Figure 11 This is a schematic diagram of the bottom support structure according to an embodiment of the present invention.

[0041] Figure 12 This is a schematic diagram of the structure of a biological packing material according to one embodiment of the present invention. Figure 13 The curves show the steady-state dissolved oxygen concentration at different rotation speeds. Figure 14 The changes in the three states of nitrogen (ammonia nitrogen NH4⁺-N, nitrite nitrogen NO2⁻-N, and nitrate nitrogen NO3⁻-N) and the ammonia nitrogen removal rate curves during reactor operation are shown. Figure 15 These are before-and-after comparison images of the packing material before and after biofilm formation. Figure 15 (a) is the polyurethane sponge filler before biofilm formation. Figure 15(b) is the packing material after the film has attached. Figure 16 This is the equivalent stress cloud diagram of the stirring tendons.

[0042] In the diagram: 1. Variable frequency motor, 2. Water inlet, 3. Worm gear reducer; 4. Main body of the device, 5. Control box, 6. Bottom support, 7. Rotating shaft, 8. Flange, 9. Motor support, 10. First circular side plate, 11. First upper side plate, 12. Second upper side plate, 13. Bending plate, 14. Water outlet, 15. Sludge discharge port, 16. Second circular side plate, 17. Stirring rib, 18. Reinforcing disc, 19. Perforated bushing, 20. Oil seal, 21. Snap ring, 22. Rolling bearing, 23. Locking nut, 24. Shaft end retaining ring, 25. Circuit breaker, 26. Fuse, 27. Variable frequency drive, 28. Arc bottom support plate, 29. Bottom support plate, 30. Side support plate, 31. Arc side support plate, 32. Arc support plate, 33. Composite caster. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "front," "rear," "left," "right," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] Figure 1-12 The image shows a preferred embodiment of the drum-type biological filter suitable for industrialized aquaculture wastewater, which includes a control box 5, a drive device, and a device body 4.

[0047] The main body 4 of the device contains biological packing balls for the attachment of microorganisms;

[0048] The main body 4 of the device includes an inlet 2, a rotating shaft 7, an outlet 14, a sludge discharge port 15, stirring ribs 17, bearings, and seals. The inlet 2 and the outlet 14 are respectively located on the side walls of the main body 4, and the sludge discharge port 15 is located at the bottom of the main body 4. The bearings and seals are provided at both ends of the main body 4. The rotating shaft 7 is axially inserted through the main body 4 and is rotatably connected to the main body 4 through the bearings and seals. There are multiple stirring ribs 17, which are evenly distributed around the rotating shaft 7 and are used to stir the water and biological packing balls inside the main body 4, so that the water and biological packing balls move synchronously.

[0049] The drive device is connected to the rotating shaft 7 for driving the rotating shaft 7 to rotate; the control box 5 is electrically connected to the drive device for controlling the speed of the drive device.

[0050] In this embodiment, there are four stirring ribs 17, which are evenly distributed at 90° intervals along the circumference of the rotating shaft 7.

[0051] In this embodiment, the driving device includes a variable frequency motor 1 and a worm gear reducer 3; the variable frequency motor 1 is connected to the worm gear reducer 3, and the worm gear reducer 3 is drively connected to the rotating shaft 7. Preferably, the worm gear reducer 3 and the rotating shaft 7 are connected by a flat key; this drives the rotation of the rotating shaft 7 and the internal stirring ribs 17. The control box 5 includes a frequency converter 27, which is electrically connected to the variable frequency motor 1 and is used to control the speed of the variable frequency motor 1, thereby driving the movement of the internal stirring ribs 17 to achieve uniform water movement and oxygenation.

[0052] In this embodiment, the worm gear reducer 3 has a reduction ratio of 80:1, the variable frequency motor 1 has a rated speed of 1380 r / min, a frequency of 50 Hz, and a power of 0.37 kW. The frequency converter 27 can achieve stepless speed regulation from 0 to 17.25 r / min. The water inlet 2 is installed 50 mm above the bottom of the first circular side plate 10, which allows for a gentler water inflow and increases the hydraulic residence time.

[0053] like Figure 3 As shown, the lower part of the outer shell of the main body 4 of the device is a cylindrical structure, including a first circular side plate 10 on the left, a second circular side plate 16 on the right, and a bent plate 13 connecting the two; the upper part of the outer shell is a rectangular structure, including two oppositely arranged first upper side plates 11 and two oppositely arranged second upper side plates 12. The two first upper side plates 11 and the two second upper side plates 12 enclose a rectangular frame to facilitate the installation of its internal parts.

[0054] like Figure 3 and Figure 4 As shown, a flange 8 and a water inlet 2 are installed on the first circular side plate 10, and an oil seal 20, a snap ring 21 and a rolling bearing 22 are installed inside the flange 8; a flange 8, a water outlet 14 and a sludge discharge port 15 are installed on the second circular side plate 16, and an oil seal 20, a snap ring 21 and a rolling bearing 22 are also installed inside the flange 8.

[0055] like Figure 4 As shown, in this embodiment, the inlet 2 is installed on the first circular side plate 10, and the center of the inlet 2 is 50mm above the bottom of the main body 4. There are four outlets 14, installed at different heights on the second circular side plate 16, so that the outlet water levels correspond to 1 / 3, 1 / 2, 2 / 3, and 5 / 6 of the internal volume of the main body 4, respectively, thus meeting multiple water treatment level requirements. The sludge discharge port 15 is installed at the bottom of the second circular side plate 16 to discharge internal sludge and water.

[0056] like Figure 5 and Figure 6 As shown, in this embodiment, inside the main body 4 of the device, the bottom sides of the four stirring ribs 17 are respectively mounted on the perforated bushings 19. Reinforcing discs 18 are provided on both sides of the stirring ribs 17, and the reinforcing discs 18 are mounted on the perforated bushings 19. The perforated bushings 19 are mounted on the rotating shaft 7, and the perforated bushings 19 and the rotating shaft 7 are fixedly connected by bolts. The top of one side of the rotating shaft 7 is threaded and fitted with a shaft end retaining ring 24 and a locking nut 23 for axial positioning of the rotating shaft 7. In this embodiment, the reinforcing discs 18 have an inner diameter of 30mm and an outer diameter of 400mm. Two reinforcing discs 18 are fixedly connected to both sides of the four stirring ribs 17 to ensure the strength of the stirring ribs 17.

[0057] like Figure 7As shown, in this embodiment, the stirring rib 17 has a thickness of 5mm, a top length L of 740mm, a top-to-bottom distance W of 386mm, and a rectangular through hole with dimensions of 95mm × 680mm × 5mm is excavated in the middle of the bottom. The through hole extends through the thickness direction of the stirring rib 17.

[0058] like Figure 8 As shown, flanges 8 are welded to the outer sides of the circular side plates at both ends of the main body 4 of the device for the installation of the rotating shaft 7. An oil seal 20, a snap ring 21 and a rolling bearing 22 are installed inside the flanges 8 to ensure the rotation and sealing of the shaft.

[0059] like Figure 9 and 10 As shown, the rotating shaft 7 is made of stainless steel, with symmetrical through holes on both sides. The left side has a keyway for connection to the worm gear reducer 3, and the right side has a threaded top for mounting the shaft end retaining ring 24 and locking nut 23. The perforated bushing 19 also has through holes, and bolts are used to connect the perforated bushing 19 to the rotating shaft 7.

[0060] In this embodiment, the seal is a skeleton oil seal, and the bearing is a deep groove ball bearing.

[0061] The control box 5 also includes a circuit breaker 25 and a fuse 26 for circuit protection.

[0062] A tripod is welded onto the main body 4 of the device for mounting the control box 5.

[0063] like Figure 11 As shown, the drum-type biological filter suitable for industrialized aquaculture wastewater also includes a bottom support 6; the main body 4 of the device is installed on the bottom support 6, and casters 33 are installed at the bottom of the bottom support 6.

[0064] In this embodiment, there are two bottom supports 6, symmetrically installed below the main body 4 of the device; each bottom support 6 includes a bottom support plate 29, an arc-shaped bottom support plate 28, a side support plate 30, an arc-shaped support plate 32, and an arc-shaped side support plate 31; the arc-shaped bottom support plate 28, the side support plate 30, and the arc-shaped support plate 32 are installed above the bottom support plate 29; the arc-shaped side support plate 31 connects the side support plate 30 and the arc-shaped support plate 32, and is also connected to the main body 4 of the device; four composite casters 33 are installed on the bottom support plate 29, and the composite casters are universal adjustable casters to realize the movement and leveling of the equipment.

[0065] like Figure 12 As shown, the drum-type biological filter suitable for industrialized aquaculture wastewater also includes biological packing material inside the main body 4 of the device. The packing balls have a diameter of 55mm and a filling rate of 30%. Polyurethane packing material with a specific surface area ≥800m² is placed inside the packing balls.2 / m 3 .

[0066] like Figures 13 to 16 As shown, the inventors verified the invention through simulation and experimentation.

[0067] Figure 13 The steady-state dissolved oxygen concentration curves are shown at different rotation speeds. The experiment was conducted at 25±1℃. The results showed that the dissolved oxygen concentration was 5.2 mg / L at a rotation speed of 2 r / min; 5.6 mg / L at a rotation speed of 3 r / min; and 6.19 mg / L at a rotation speed of 4 r / min. Compared with the 2 r / min condition, the dissolved oxygen concentration increased by approximately 19% at 4 r / min, proving that the present invention can achieve efficient oxygenation without aeration.

[0068] Figure 14 The changes in the three states of nitrogen (ammonia nitrogen NH4⁺-N, nitrite nitrogen NO2⁻-N, and nitrate nitrogen NO3⁻-N) and the ammonia nitrogen removal rate curves were shown during reactor operation. Artificially synthesized aquaculture wastewater (ammonia nitrogen concentration 10 mg / L) was used as the treatment target. A strategy of initial aeration followed by gradient influent acclimatization was employed, with continuous operation at a hydraulic retention time of 24 h and a final rotation speed of 4 r / min. Results showed that the effluent ammonia nitrogen concentration remained stable below 0.02 mg / L, with an ammonia nitrogen removal rate approaching 100%; the effluent nitrite nitrogen concentration remained stable below 0.03 mg / L; and nitrate nitrogen remained at a high stable value of 11.0-11.5 mg / L, indicating that the system achieved complete nitrification.

[0069] Figure 15 These are before-and-after comparison images of the packing material before and after biofilm formation. Figure 15 'a' represents the polyurethane sponge filler before biofilm formation. Figure 15 b represents the packing material after biofilm formation. Before biofilm formation, the packing material exhibits a clear three-dimensional mesh-like open structure with smooth pore walls. After biofilm formation, the overall color of the packing material significantly darkens, the edges of the skeleton are uniformly wrapped by dark biofilm, and a distinct and dense biofilm layer is formed in the pores while retaining some connectivity. No large-area pore blockage occurs, verifying the adaptability of the internal flow field of this invention to biofilm growth.

[0070] Figure 16 This is the equivalent stress contour plot of the stirring rib. Static simulation was performed using ANSYS Workbench. The results show that the maximum equivalent stress of the stirring rib is 6.16 MPa, which is far less than the allowable stress of 304 stainless steel (137 MPa), indicating that the structure is safe and reliable. The working process of this invention:

[0071] The inlet 2 allows water to enter from below, and the four outlets 14 allow for free selection of water outlets. The main body of the device consists of aquaculture wastewater and biological packing balls. The control box 5 is connected to the variable frequency motor 1, which in turn is connected to the worm gear reducer 3. The worm gear reducer 3 is connected to the rotating shaft 7 via a key. Stepless speed regulation is achieved by adjusting the frequency converter, driving the rotation of the rotating shaft and the internal stirring ribs, thereby promoting the uniform movement of water and biological packing balls inside the device, reducing dead zones within the equipment, and increasing the dissolved oxygen content in the water.

[0072] According to experimental tests, when the water level is at 2 / 3 position, a rotation speed of 2 r / min can increase the dissolved oxygen concentration to 5.2 mg / L; at a rotation speed of 3 r / min, the dissolved oxygen concentration can be increased to 5.6 mg / L; and at 4 r / min, the dissolved oxygen concentration can be increased to 6.19 mg / L. The total oxygen volumetric mass transfer coefficient at rotation speeds of 2 r / min, 3 r / min, and 4 r / min are 3.03 l / h, 3.92 l / h, and 4.88 l / h, respectively. The corresponding energy consumption per unit volume of water is 0.0554 kW·h / m³, 0.1868 kW·h / m³, and 0.4428 kW·h / m³, respectively. Traditional biological rotating discs consume 0.05-0.15 kW·h / m³ of energy per unit water volume, while traditional MBBRs (with dissolved oxygen of 3 mg / L-3.5 mg / L) consume 0.3-0.36 kW·h / m³ of energy per unit water volume. This invention achieves a higher dissolved oxygen level under low energy consumption and rotational speed conditions, significantly outperforming traditional biological rotating discs and MBBRs.

[0073] Figure 13 The steady-state dissolved oxygen concentration curves are shown at different rotation speeds. The experiment was conducted at 25±1℃. The results showed that the dissolved oxygen concentration was 5.2 mg / L at a rotation speed of 2 r / min; 5.6 mg / L at a rotation speed of 3 r / min; and 6.19 mg / L at a rotation speed of 4 r / min. Compared with the 2 r / min condition, the dissolved oxygen concentration increased by approximately 19% at 4 r / min, proving that the present invention can achieve efficient oxygenation without aeration.

[0074] The steady-state dissolved oxygen concentrations at different rotation speeds were measured experimentally and are shown in Table 1.

[0075] Table 1 Steady-state dissolved oxygen concentration at different rotation speeds

[0076] (Note: Under normal pressure and temperature at 25°C, the saturated dissolved oxygen concentration Cs in pure water is approximately 8.26 mg / L.)

[0077] Figure 14This study presents the changes in the three states of nitrogen (ammonia nitrogen NH4⁺-N, nitrite nitrogen NO2⁻-N, and nitrate nitrogen NO3⁻-N) and the ammonia nitrogen removal rate curves during reactor operation. Artificially synthesized aquaculture wastewater (ammonia nitrogen concentration 10 mg / L) was used as the treatment target. After 60 days of continuous operation, a strategy of initial aeration followed by gradient influent acclimatization was employed, with a hydraulic retention time of 24 h and a final rotation speed of 4 r / min. The results showed that the effluent ammonia nitrogen concentration remained stable below 0.02 mg / L, with an ammonia nitrogen removal rate approaching 100%; the effluent nitrite nitrogen concentration remained stable below 0.03 mg / L; and the nitrate nitrogen concentration remained at a high and stable value of 11.0-11.5 mg / L, indicating that the system achieved complete nitrification.

[0078] Figure 15 These are before-and-after comparison images of the packing material before and after biofilm formation. Figure 15 'a' represents the polyurethane sponge filler before biofilm formation. Figure 15 b represents the packing material after biofilm formation. Before biofilm formation, the packing material exhibits a clear three-dimensional mesh-like open structure with smooth pore walls. After biofilm formation, the overall color of the packing material significantly darkens, the edges of the skeleton are uniformly wrapped by dark biofilm, and a distinct and dense biofilm layer is formed in the pores while retaining some connectivity. No large-area pore blockage occurs, verifying the adaptability of the internal flow field of this invention to biofilm growth.

[0079] Figure 16 The image shows the equivalent stress contour plot of the stirring bar. Static simulation was performed using ANSYS Workbench. The results show that the maximum equivalent stress of the stirring bar is 6.16 MPa, which is much lower than the allowable stress of 304 stainless steel (137 MPa), indicating that the structure is safe and reliable.

[0080] Furthermore, based on computational fluid dynamics (CFD) simulation optimization, numerical simulations were conducted on nine different stirring rib configurations. The results show that when the stirring rib adopts a structure of "a 95mm×680mm×5mm cuboid with the bottom center removed" (i.e., the 386-100mm configuration), the average flow field velocity is stable at 0.27-0.31m / s, the dead zone ratio is less than 5%, the turbulent kinetic energy reaches 0.0191-0.0307m² / s², the packing is uniformly suspended, and the overall performance is optimal. Based on this, the operating parameters were optimized, and a rotation speed of 4r / min and an immersion ratio of 2 / 3 were determined. At this point, the average flow field velocity is stable at 0.18-0.20m / s, the packing is uniformly suspended, and there are no sediment dead zones. Energy consumption tests show that the theoretical daily power consumption under the 4r / min operating condition is approximately 3.6kWh / d, which significantly reduces operating energy consumption compared to the traditional MBBR process.

[0081] The above experimental data fully verify that the present invention has the advantages of uniform flow field, high dissolved oxygen, high ammonia nitrogen removal efficiency, low energy consumption, and safe and reliable structure.

[0082] In this embodiment, the frequency converter 27 inside the control box 5 is connected to the frequency converter motor 1 and the worm gear reducer 3. By adjusting the frequency converter 27, the speed of the rotating shaft 7 can be infinitely adjusted, thereby driving the internal stirring ribs 17 to rotate and driving the water and biological packing balls to move uniformly, achieving aeration without aeration. At the same time, the rigidity of the stirring ribs 17 can be ensured by adding a reinforcing disc 18. The lower part of the outer shell of the main body 4 is designed as a cylindrical structure and the upper part as a cuboid structure, which is conducive to improving the uniformity of the internal flow field, reducing the flow dead zone, reducing energy consumption, and increasing the dissolved oxygen concentration.

[0083] The inlet 2 is installed on the first circular side plate 10, 50mm from the bottom, and the four outlets 14 are installed on the second circular side plate 16, corresponding to 1 / 3, 1 / 2, 2 / 3, and 5 / 6 of the internal volume of the main body 4, respectively. This arrangement can meet the needs of multiple treatment water levels, making the water inlet more gentle, extending the hydraulic retention time, improving the water treatment effect and operational flexibility.

[0084] Optionally, a sealing cover is installed at the top of the cuboid structure on the main body 4 of the device, and a one-way exhaust valve is installed on the cover. When denitrification is required, the sealing cover is installed to create an oxygen-deficient environment inside the equipment, while organic carbon sources are added to the water. Denitrification can be achieved using facultative microorganisms attached to the existing biological packing material. In this case, the equipment is used as a standalone denitrification tank, rather than for simultaneous nitrification and denitrification.

[0085] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0086] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drum-type biological filter suitable for industrialized aquaculture wastewater, characterized in that, Includes control box (5), drive unit and device body (4); The main body (4) of the device contains biological filler balls for the attachment of microorganisms; The main body (4) of the device includes an inlet (2), a rotating shaft (7), an outlet (14), a sludge discharge port (15), stirring ribs (17), bearings, and seals. The inlet (2) and outlet (14) are respectively located on the side wall of the main body (4), and the sludge discharge port (15) is located at the bottom of the main body (4). The bearings and seals are provided at both ends of the main body (4). The rotating shaft (7) is axially inserted through the main body (4) and rotatably connected to the main body (4) through the bearings and seals. There are multiple stirring ribs (17) evenly distributed around the rotating shaft (7) to stir the water and biological packing balls inside the main body (4) so ​​that the water and biological packing balls move synchronously. The drive device is connected to the rotating shaft (7) for driving the rotating shaft (7) to rotate; The control box (5) is electrically connected to the drive device and is used to control the speed of the drive device.

2. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 1, characterized in that, There are four stirring ribs (17), which are evenly distributed at 90° intervals along the circumference of the rotating shaft (7).

3. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 2, characterized in that, The stirring rib (17) has a thickness of 5mm, a top length L of 740mm, a top-to-bottom distance W of 386mm, and a rectangular through hole with a length, width, and thickness of 95mm × 680mm × 5mm is excavated in the middle of the bottom. The through hole extends through the thickness direction of the stirring rib (17).

4. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 2, characterized in that, The bottom sides of the four stirring ribs (17) are respectively mounted on the perforated bushings (19). The stirring ribs (17) are respectively provided with reinforcing discs (18). The reinforcing discs (18) are mounted on the perforated bushings (19). The perforated bushings (19) are mounted on the rotating shaft (7). The perforated bushings (19) and the rotating shaft (7) are fixedly connected by bolts. The top of one side of the rotating shaft (7) is provided with threads and is equipped with a shaft end retaining ring (24) and a locking nut (23) for axial positioning of the rotating shaft (7). The reinforcing discs (18) have an inner diameter of 30mm and an outer diameter of 400mm. The two reinforcing discs (18) are fixedly connected to the two sides of the four stirring ribs (17).

5. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 1, characterized in that, The drive device includes a variable frequency motor (1) and a worm gear reducer (3); the variable frequency motor (1) is connected to the worm gear reducer (3), and the worm gear reducer (3) is connected to the rotating shaft (7) in a transmission connection; the control box (5) includes a frequency converter (27), which is electrically connected to the variable frequency motor (1) and is used to control the speed of the variable frequency motor (1).

6. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 1, characterized in that, It also includes a bottom bracket (6); the main body (4) of the device is mounted on the bottom bracket (6), and casters (33) are mounted on the bottom of the bottom bracket (6).

7. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 6, characterized in that, There are two bottom brackets (6), which are symmetrically installed below the main body (4) of the device. Each bottom bracket (6) includes a bottom support plate (29), an arc bottom support plate (28), a side support plate (30), an arc support plate (32), and an arc side support plate (31). The arc bottom support plate (28), the side support plate (30), and the arc support plate (32) are installed above the bottom support plate (29). The arc side support plate (31) is connected between the side support plate (30) and the arc support plate (32), and is also connected to the main body (4). The bottom support plate (29) has holes for four composite casters (33), which are universal adjustable casters.

8. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 1, characterized in that, The lower part of the outer shell of the main body (4) of the device is a cylindrical structure, including a first circular side plate (10) on the left, a second circular side plate (16) on the right, and a bent plate (13) connecting the two; the upper part of the outer shell is a rectangular structure, including two oppositely arranged first upper side plates (11) and two oppositely arranged second upper side plates (12), which together form a rectangular frame.

9. The drum-type biological filter for industrialized aquaculture wastewater as described in claim 8, characterized in that, The inlet (2) is installed on the first circular side plate (10), and the center of the inlet (2) is 50mm away from the bottom of the main body (4) of the device. There are four outlets (14), which are installed at different heights on the second circular side plate (16), so that the water level corresponds to 1 / 3, 1 / 2, 2 / 3 and 5 / 6 of the internal volume of the main body (4) of the device. The sludge discharge port (15) is installed at the bottom of the second circular side plate (16).

10. The drum-type biological filter for industrialized aquaculture wastewater according to claim 1, characterized in that, The control box (5) also includes a circuit breaker (25) and a fuse (26).

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