A sewage treatment system based on compact magnetic powder reinforced activated sludge

Abstract

The utility model discloses a kind of sewage treatment systems based on dense magnetic powder reinforced activated sludge, comprising: mixing pool, its input port is used to connect the pipeline of pretreated sewage, mixing pool is equipped with stirring assembly to fully mix sewage and magnetic powder;Magnetic powder feeding mechanism is used to put magnetic powder to mixing pool;Biological reaction pool includes communicating anaerobic tank, anoxic tank, aerobic tank in turn, anaerobic tank is communicated with the output port of mixing pool, anaerobic tank, anoxic tank are equipped with stirring assembly, the bottom of aerobic tank is provided with aeration pipeline to maintain the stability of dissolved oxygen, aerobic tank is by first nitration liquid return pipeline, nitration liquid reflux pump, second nitration liquid return pipeline Nitration liquid is returned to anoxic tank. By introducing superfine magnetic powder as carrier in mixing pool, dense magnetic reinforced activated sludge is formed, not only the biological denitrification efficiency is strengthened, but also the settling performance of sludge is significantly improved, and the toughness of overall system to respond water quality change and impact load is improved.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology and relates to a wastewater treatment system based on dense magnetic powder-reinforced activated sludge. Background Technology

[0002] With continuous social development and the overall development pattern of transforming old growth drivers into new ones and building new urbanization, the adaptive expansion and technological upgrading of existing wastewater treatment plants have become an inevitable trend in the industry. Faced with multiple challenges such as scarce land resources, high requirements for operational continuity, and urgent needs for water quality improvement, how to upgrade and restructure existing wastewater treatment plants to significantly improve effluent quality without increasing land use, altering existing civil engineering and structures, ensuring uninterrupted water supply, affecting the surrounding environment and production output, and simultaneously maintaining the quality of existing treated water has become a key problem that many urban wastewater treatment plants in my country urgently need to solve. Utility Model Content

[0003] Based on this, and in response to the shortcomings of existing technologies, this utility model provides a wastewater treatment system based on dense magnetic powder-reinforced activated sludge. Under the premise of not increasing additional land use, not modifying existing civil engineering and structures, ensuring uninterrupted water supply for production, not affecting the surrounding environment and production output, and not reducing the quality of existing treated water, it can achieve in-situ quality improvement and efficiency enhancement of wastewater treatment plants.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A wastewater treatment system based on dense magnetic powder-reinforced activated sludge includes:

[0006] A mixing tank, the inlet of which is used to connect to a pipe for pre-treated wastewater, is equipped with a stirring component to fully mix the wastewater and magnetic powder;

[0007] A magnetic powder feeding mechanism is used to feed magnetic powder into a mixing tank;

[0008] The biological reactor includes an anaerobic tank, an anoxic tank, and an aerobic tank connected in sequence. The anaerobic tank is connected to the outlet of the mixing tank. Both the anaerobic tank and the anoxic tank are equipped with stirring components. The bottom aeration pipe of the aerobic tank is used to maintain the stability of dissolved oxygen.

[0009] Optionally, the magnetic powder feeding mechanism is a dry powder feeding device or a screw + pump device.

[0010] Preferably, the magnetic powder has a particle size of 10–60 μm, and / or the magnetic susceptibility of the magnetic powder is 30–70 emu / g, and the magnetic biocapacitance of the magnetic powder is in the range of (5–10) × 10⁻⁶. -4 F / mL.

[0011] Optionally, the system also includes a quantitative control module, which comprises a sludge concentration meter, a water level gauge, and a controller. The sludge concentration meter is installed on the inner wall of the mixing tank to detect the sludge content in the wastewater. The water level gauge is used to detect the wastewater level in the mixing tank. The controller is used to receive the sludge content information detected by the sludge concentration meter and the wastewater level information transmitted by the water level gauge, and to calculate the mass of activated sludge in the mixing tank accordingly. The controller is electrically connected to the magnetic powder feeding mechanism to control the amount of magnetic powder added by the magnetic powder feeding mechanism.

[0012] Furthermore, the sludge concentration meter is model T-BD5CMD-SS4210.

[0013] Preferably, the mass ratio of magnetic powder to activated sludge is controlled at 0.5 to 1.5:1.

[0014] Optionally, the system also includes a secondary sedimentation tank for rapid settling of high-density magnetic sludge flocs. The inlet of the secondary sedimentation tank is connected to the outlet of the aerobic tank to allow wastewater from the aerobic tank to flow into the secondary sedimentation tank. The bottom of the secondary sedimentation tank is connected to the mixing tank via a return assembly to allow most of the sludge-magnetic powder mixture to be directly recycled into the mixing tank. The return assembly includes a return sludge pipe I, a return sludge pump, and a return sludge pipe II. One end of the return sludge pipe I is connected to the bottom of the secondary sedimentation tank, and the other end of the return sludge pipe I is connected to the return sludge pump. The return sludge pump is connected to the mixing tank via the return sludge pipe II.

[0015] Furthermore, the secondary sedimentation tank is also equipped with a magnetic powder recovery component to recover magnetic powder from the sludge. The magnetic powder recovery component includes a residual sludge pipe, a magnetic separation device, and a magnetic powder recovery pipe. One end of the residual sludge pipe is connected to the bottom of the secondary sedimentation tank, and the other end of the residual sludge pipe is connected to the magnetic separation device. The magnetic separation device uses a magnetic field to adsorb and separate magnetic powder, and collects the magnetic powder through the magnetic powder recovery pipe.

[0016] The above technical solution involves mixing magnetic powder with an aqueous solution in a mixing tank at a certain ratio, followed by mechanical stirring to form a high-concentration magnetic powder suspension. This process not only promotes the uniform dispersion of magnetic powder particles in the water but also breaks down potential agglomeration structures through the shear force and eddy current effect generated by stirring, ensuring the full dispersion and stable suspension of the magnetic powder particles. By introducing ultrafine magnetic powder as a carrier, dense magnetically enhanced activated sludge is formed, which not only enhances the biological denitrification efficiency but also significantly improves the sludge settling performance and enhances the overall system's resilience to water quality changes and shock loads, ultimately achieving in-situ quality improvement and efficiency enhancement of the wastewater treatment plant. This invention integrates modules for automatic magnetic powder dosing, magnetic sludge reflux, magnetic powder separation and recovery, and online concentration monitoring, forming a highly efficient closed-loop cycle. Combined with a sludge concentration sensor and a water level monitoring system, the magnetic powder dosing can be adjusted in real time according to the MLSS, ensuring precise dosing and efficient coordinated operation of the system under different water quality conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the wastewater treatment system of this utility model, which utilizes magnetic materials to enhance the denitrification of low C / N wastewater and sludge settling.

[0018] Figure 2 This is a diagram showing the pollutant removal effect in Example 1.

[0019] Figure 3 This is a diagram showing the sludge settling effect in Example 1.

[0020] Figure 4 This is a diagram showing the pollutant removal effect in Example 2.

[0021] Figure 5 This is a diagram showing the sludge settling effect in Example 2.

[0022] Figure 6 This is a diagram showing the pollutant removal effect in Example 3.

[0023] Figure 7 This is a diagram showing the sludge settling effect in Example 3.

[0024] Figure 8 This is a graph showing the electron transfer efficiency of microorganisms in Example 1.

[0025] Figure 9 This is a graph showing the electron transfer efficiency of microorganisms in Example 2.

[0026] Figure 10 This is a graph showing the electron transfer efficiency of microorganisms in Example 3.

[0027] Explanation of reference numerals in the attached figures

[0028] 1-Inlet pipe I, 2-Inlet pump, 3-Inlet pipe II, 4-Mixing zone mixer, 5-Anaerobic zone mixer, 6-Anoxic zone mixer, 7-Mixing tank, 8-Anaerobic tank, 9-Anoxic tank, 10-Aerobic tank, 11-Secondary sedimentation tank, 12-Aeration head, 13-Aeration pipe, 14-Aeration pump, 15-Nitrified liquor return pipe I, 16-Nitrified liquor return pump, 17-Nitrified liquor return pipe II, 18-Return sludge pipe I, 19-Return sludge pump, 20-Return sludge pipe II, 21-Excess sludge pipe I, 22-Magnetic separation device, 23-Magnetic powder recovery pipe, 24-Excess sludge discharge pipe, 25-Effluent pipe. Detailed Implementation

[0029] In response to the practical problems of low COD concentration, poor biodegradability, and large fluctuations in influent during the rainy and dry seasons in urban sewage in my country, this utility model proposes a process technology route applicable to newly built and renovated sewage treatment plants.

[0030] This utility model provides a wastewater treatment system based on dense magnetic powder-reinforced activated sludge, comprising:

[0031] A mixing tank, the inlet of which is used to connect to a pipe for pre-treated wastewater, is equipped with a stirring component to fully mix the wastewater and magnetic powder;

[0032] A magnetic powder feeding mechanism is used to feed magnetic powder into a mixing tank;

[0033] The biological reactor includes an anaerobic tank, an anoxic tank, and an aerobic tank connected in sequence. The anaerobic tank is connected to the outlet of the mixing tank. Both the anaerobic and anoxic tanks are equipped with stirring components to agitate the wastewater. These stirring components are agitators, located at the top of the tank and driven by a motor. The aerobic tank has a bottom aeration pipe to maintain stable dissolved oxygen levels. It should be noted that wastewater can flow between the mixing tank, anaerobic tank, anoxic tank, and aerobic tank via pipes and pumps, and valves can be installed on the pipes. Wastewater can also flow between the mixing tank, anaerobic tank, anoxic tank, and aerobic tank through level differences between the containers; no further restrictions are imposed here.

[0034] This invention utilizes the high density, magnetic properties, and surface microstructure of magnetic powder to construct a highly efficient composite sludge system. This technology enhances the extracellular electron transfer rate between microorganisms and the interaction between magnetic powder and microorganisms, thereby increasing bioelectric capacity and accelerating the conversion of dissolved oxygen (DO), organic matter (COD), and ammonia nitrogen (NH4+). + -N) and nitrates (NO3) -The magnetic powder significantly reduced the reaction rate of substrates such as nitrogen (N-N) and decreased the accumulation of intermediate products. As a core carrier in activated sludge flocs, the magnetic powder optimized sludge settling performance, shortened settling time, and reduced sedimentation tank volume. The introduction of magnetic powder significantly promoted the enrichment and activity of denitrification-related functional microorganisms (such as ammonia-oxidizing bacteria and denitrifying bacteria), further improving biological denitrification efficiency and achieving in-situ quality improvement and efficiency enhancement by optimizing the microbial community structure. Furthermore, the porous structure of the magnetic powder surface allows microorganisms to quickly attach, inhabit, and grow there, while reducing the secretion of extracellular polymeric substances (EPS), thus reducing excess sludge production by more than 30%, effectively lowering sludge treatment and disposal costs.

[0035] In one preferred embodiment of this invention, the magnetic powder feeding mechanism is a dry powder feeding device or a screw + pump device. Both the dry powder feeding device and the screw + pump device are existing technologies and will not be described in detail here.

[0036] In one preferred embodiment of this invention, the magnetic powder has a particle size of 10–60 μm, a magnetization of 30–70 emu / g, and a magnetic biocapacitance range of (5–10) × 10⁻⁶. -4 F / mL. The magnetic powder is spherical or nearly spherical in shape. Spherical magnetic powder has a larger specific surface area and better flowability, thus significantly improving adsorption performance. There is a functional synergistic range between the magnetic powder particle size (10–60 μm) and magnetization (30–70 emu / g), which is not a conventional optimization result that can be easily obtained through simple experiments in this field. This combination of parameters ensures the embedding stability of the magnetic powder in the activated sludge structure while avoiding the problems of agglomeration and dispersion failure, providing an irreplaceable material basis for the construction of CMAS. This is a fundamental expansion of the traditional idea of ​​"magnetic powder as a settling aid".

[0037] In one preferred embodiment of this utility model, the system further includes a quantitative control module, which comprises a sludge concentration meter, a water level gauge, and a controller. The sludge concentration meter is installed on the inner wall of the mixing tank to detect the sludge content in the wastewater. The water level gauge is used to detect the wastewater level in the mixing tank. The controller receives the sludge content information detected by the sludge concentration meter and the wastewater level information transmitted by the water level gauge, and thereby obtains the mass of activated sludge in the mixing tank (this is prior art, calculating the mass of activated sludge in the mixing tank based on the volume of wastewater and the sludge content). The controller is electrically connected to the magnetic powder feeding mechanism to control the amount of magnetic powder added by the magnetic powder feeding mechanism. Since the mass ratio of magnetic powder to activated sludge is controlled at 0.5 to 1.5:1, the controller can determine the magnetic powder addition range based on the mass of activated sludge, and the controller controls the magnetic powder feeding mechanism to automatically add the magnetic powder. Further, the sludge concentration meter is an insertion type sludge concentration meter: the sensor is directly immersed in the medium, and the model of the sludge concentration meter is T-BD5CMD-SS4210. Sludge concentration meters can also be replaced by ultrasonic online monitoring devices.

[0038] In one preferred embodiment of this utility model, the system further includes a secondary sedimentation tank for rapidly settling high-density magnetic sludge flocs. The inlet of the secondary sedimentation tank is connected to the outlet of the aerobic tank to allow wastewater from the aerobic tank to flow into the secondary sedimentation tank. The bottom of the secondary sedimentation tank is connected to the mixing tank via a return assembly to allow most of the sludge-magnetic powder mixture to be directly recycled into the mixing tank. The return assembly includes a return sludge pipe I, a return sludge pump, and a return sludge pipe II. One end of the return sludge pipe I is connected to the bottom of the secondary sedimentation tank, and the other end of the return sludge pipe I is connected to the return sludge pump. The return sludge pump is connected to the mixing tank via the return sludge pipe II.

[0039] In one preferred embodiment of this utility model, the secondary sedimentation tank is further provided with a magnetic powder recovery component to recover magnetic powder from the sludge. The magnetic powder recovery component includes a residual sludge pipe, a magnetic separation device, and a magnetic powder recovery pipe. One end of the residual sludge pipe is connected to the bottom of the secondary sedimentation tank, and the other end of the residual sludge pipe is connected to the magnetic separation device. The magnetic separation device uses a magnetic field to adsorb and separate the magnetic powder, and collects the magnetic powder through the magnetic powder recovery pipe.

[0040] The technical solution of this utility model will be further described below with reference to the accompanying drawings, but the scope of protection claimed by this utility model is not limited thereto.

[0041] (1) Selection of magnetic powder

[0042] Magnetization is a core indicator for evaluating the performance of magnetic powder, playing a decisive role in its adsorption efficiency, separation capability, and response speed. In selecting magnetic powder, this invention first measures the saturation magnetization, coercivity, and remanence of candidate magnetic powders using a vibrating sample magnetometer (VSM). To meet the requirements for treating high-concentration pollutants, magnetic powders with a saturation magnetization between 30 and 70 emu / g are carefully selected. This range of magnetization not only ensures that the magnetic powder possesses sufficient magnetic force to effectively adsorb target pollutants but also utilizes the magnetotactic properties of microorganisms to promote their enrichment and growth on the magnetic powder surface, accelerating the formation of dense magnetic powder-reinforced activated sludge (CMAS) and significantly improving the pollutant removal rate.

[0043] The particle size and morphology of magnetic powder directly affect its dispersibility, sedimentation performance, and specific surface area in water. To optimize performance, this invention employs a laser particle size analyzer to precisely control the particle size of the magnetic powder, ensuring a uniform distribution within the range of 10–60 μm. Magnetic powder with excessively large particle sizes may cause equipment blockage, while those with excessively small particle sizes are prone to over-dispersion, reducing utilization efficiency. For magnetic powder that does not meet the particle size requirements, this invention uses physical grinding technology to adjust its morphology to spherical or near-spherical shapes. Spherical magnetic powder has a larger specific surface area and better flowability, thereby significantly improving adsorption performance.

[0044] Magnetic materials play a crucial role in denitrification. They not only act as electron sources or electron transfer promoters, enhancing the kinetic efficiency of the denitrification reaction, but also positively influence the activity of specific denitrifying bacterial communities by improving the electron transfer mechanisms of microorganisms. These communities often rely on exogenous electron donors to complete the nitrate reduction process. This invention utilizes the capacitance effect generated when magnetic materials interact with microorganisms, i.e., "magnetobiocapacitance." This effect provides strong support for the denitrification process by optimizing electron transfer pathways and enhancing biofilm formation. The interaction between magnetic materials and the surface charge of microbial cells promotes efficient electron conduction within the biofilm, thus exhibiting significant capacitance characteristics at the electrochemical level. To quantify the specific impact of magnetobiocapacitance on denitrification efficiency, this invention uses cyclic voltammetry (CV) to test the electrochemical performance of magnetic powder and determine its magnetobiocapacitance. Within a selected magnetobiocapacitance range (5–10 × 10⁻⁶), the magnetobiocapacitance is measured. -4 (F / mL) Under the action of magnetic materials, the resistance to electron transfer is effectively reduced, the electron transfer efficiency of bacteria is improved, and the thickness, density and electron transfer capacity of the biofilm are regulated, thereby further enhancing the activity and denitrification efficiency of the denitrifying bacteria.

[0045] (2) Magnetic powder addition method

[0046] Magnetic powder added directly to a treatment system without proper pretreatment often encounters significant agglomeration problems. This agglomeration results in highly irregular shapes and sizes of magnetic powder particles, some even forming large, sizable aggregates. The presence of agglomerated magnetic powder not only severely reduces its utilization efficiency but can also adversely affect the overall performance of the entire magnetic activated sludge system. Specifically, agglomeration reduces the effective specific surface area of ​​the magnetic powder particles, thereby decreasing their contact opportunities with target pollutants and significantly reducing pollutant removal efficiency. Furthermore, agglomerated magnetic powder poses a potential threat to sludge settling performance. Due to the increased volume and mass of agglomerated particles, their settling velocity in water may change, leading to poor sludge separation and ultimately affecting effluent quality. More seriously, these large-sized agglomerated magnetic powder particles are highly prone to clogging the pipes, filter media, or reactors of treatment equipment, thus interfering with the smooth operation of the entire wastewater treatment system and even causing system malfunctions.

[0047] This invention introduces a key pretreatment step—magnetic powder maturation. This step aims to optimize the charge distribution characteristics and hydrophilicity of the magnetic powder surface through a series of physicochemical methods, thereby effectively weakening the mutual attraction between particles and fundamentally reducing the tendency to agglomerate. Specifically, ultrafine magnetic powder is mixed with an aqueous solution at a certain ratio (2% to 5% by volume), followed by mechanical stirring to form a high-concentration magnetic powder suspension. This process not only promotes the uniform dispersion of magnetic powder particles in water but also further breaks down potential agglomeration structures through the shear force and eddy current effect generated by stirring, ensuring sufficient dispersion and stable suspension of the magnetic powder particles. Through maturation treatment, the dispersibility of the magnetic powder is significantly improved in practical applications. The magnetic powder particles can better contact the target pollutants, thereby improving the pollutant removal efficiency. The optimized magnetic powder suspension also improves the settling performance of sludge. In addition, due to the reduction in agglomeration, the risk of clogging of the treatment equipment is significantly reduced, providing a strong guarantee for the long-term stable operation of the wastewater treatment system.

[0048] (3) Magnetic powder dosage

[0049] This invention innovatively designs a flexible magnetic powder dosing ratio control strategy to address diverse influent water quality conditions. The aim is to achieve the optimal ratio of magnetic powder to activated sludge, thereby maximizing treatment efficiency and ensuring stable effluent quality compliance. Specifically, the mass ratio of magnetic powder to activated sludge (MLSS) is controlled within the range of 0.5 to 1.5:1 to adapt to different water quality characteristics. For influent with a high carbon-to-nitrogen ratio (C / N ratio > 10), this invention recommends a lower magnetic powder dosing ratio, i.e., a magnetic powder:activated sludge mass ratio of 0.5:1. This ratio effectively utilizes the abundant organic matter in the wastewater, promotes microbial activity, and avoids waste of magnetic powder resources. For wastewater with a medium C / N ratio (C / N (3-10)), a 1:1 magnetic powder dosing ratio is used. Within this range, although the organic matter content is lower than before, the microbial community still maintains high activity and treatment capacity. An appropriate amount of magnetic powder can further enhance the adsorption and degradation efficiency of microorganisms, ensuring that the effluent quality meets the expected standards. For wastewater with low C / N (<3), the mass ratio of magnetic powder to activated sludge is increased to 1.2:1 or higher, aiming to accelerate nitrogen conversion and removal through the strengthening effect of magnetic powder and maintain stable system operation.

[0050] (4) System operation

[0051] Pretreated wastewater, matured magnetic powder suspension, and returned sludge are efficiently mixed in a mixing tank to form dense magnetically enhanced activated sludge (CMAS). The mixed wastewater flows sequentially through anaerobic, anoxic, and aerobic zones. Within the reactor, based on the microbial magnetic effect, microorganisms rapidly attach to and grow on the surface of the magnetic powder. The magnetic powder, with its high specific surface area and excellent adsorption capacity, adsorbs a large number of denitrifying bacteria and constructs a highly efficient reaction interface, significantly accelerating the denitrification reaction and improving nitrogen removal efficiency. As the reaction progresses, the resulting high-density sludge flocs exhibit rapid settling performance in the secondary sedimentation tank, ensuring efficient sludge separation and return. Most of the magnetic powder is recycled through the sludge return system, while the remaining magnetic powder is recovered and purified by a magnetic separation device for resource utilization. Throughout the entire process, the addition and recycling of magnetic powder are highly optimized, effectively reducing operating costs and significantly improving wastewater treatment efficiency and system stability.

[0052] 3. Processing efficiency under different conditions

[0053] Control group:

[0054] The MLSS (mixed liquor suspended solids) concentration of the wastewater was 4000 mg / L, the COD (chemical oxygen demand) concentration was 200–215 mg / L, and the NO3 concentration was [missing information]. -The -N (nitrate) concentration is 45-50 mg / L, and the pH value is 7.2. Unlike Examples 1-3, no magnetic powder is added. Wastewater enters the mixing tank 7 through inlet pipes 1 and 3 under the action of inlet pump 2. The added magnetic powder is thoroughly mixed with the sludge returned from the secondary sedimentation tank via sludge return pipe 23 under the action of mixer 4. The effluent from the mixing tank sequentially passes through anaerobic zone 8, anoxic zone 9, and aerobic zone 10, and is thoroughly mixed under the action of mixer 8, mixer 9, and microporous aerator head 12. The aerobic tank 10 maintains stable dissolved oxygen levels through aeration pipe 13 and microporous aerator head 12 under the action of aeration pump 14. Simultaneously, nitrified liquid is returned to anoxic tank 9 through nitrification liquid return pipe 15, nitrification liquid return pump 16, and nitrification liquid return pipe 17. The reactor operates continuously for 28 days.

[0055] 1) Example 1

[0056] In this embodiment, the MLSS (mixed liquor suspended solids) concentration of the influent wastewater is 4000 mg / L, the COD (chemical oxygen demand) concentration is 200–215 mg / L, and the NO3 concentration is [missing information]. - The -N (nitrate) concentration was 45–50 mg / L, the pH value was 7.2, the magnetic powder used was spherical metal powder with a diameter of 10 μm, the magnetic induction intensity was 64.2 emu / g, and the magnetic biocapacitance was 7.1 × 10⁻⁶. -4 F / mL, magnetic powder addition ratio is 1:1.

[0057] As attached Figure 1 As shown, wastewater enters the mixing tank 7 through inlet pipes 1 and 3 under the action of inlet pump 2. The added magnetic powder and the sludge returned through the secondary sedimentation tank sludge return pipe 23 are fully mixed under the action of the mixing tank agitator 4. The effluent from the mixing tank will sequentially pass through the anaerobic zone 8, the anoxic zone 9, and the aerobic zone 10, and be fully mixed under the action of agitator 8, agitator 9, and microporous aerator head 12. The dissolved oxygen in the aerobic tank 10 is maintained at a stable level by aeration pump 14 through aeration pipe 13 and microporous aerator head 12. At the same time, the nitrified liquid is returned to the anoxic tank 9 through nitrification liquid return pipe 15, nitrification liquid return pump 16, and nitrification liquid return pipe 17. In the biological reactor, the magnetic powder attracts microorganisms to attach and grow on its surface by relying on its own magnetism and acting as a carrier, thereby achieving efficient denitrification of wastewater and ensuring stable effluent quality.

[0058] High-density magnetic sludge flocs settle rapidly in the secondary sedimentation tank 11. Most of the magnetic powder in the sludge can be directly recycled in the mixing tank 7 through the first return sludge pipe 18, the return sludge pump 19, and the second return sludge pipe 20. The magnetic powder in the remaining sludge is recycled through the remaining sludge pipe 21, the magnetic separation device 22, and the magnetic powder recovery pipe 23.

[0059] As attached Figure 2 As shown in the figure, the experimental results indicate that after 28 days of continuous operation, the nitrate concentration in the effluent was 6.9 mg / L, with a nitrate removal rate of 84.7% and a COD concentration of 20 mg / L, achieving a COD removal rate of 90.4%. The reactor successfully started up and operated stably, and the effluent quality met the requirements of Class IV surface water (TN < 15 mg / L, COD < 30 mg / L). (See attached figure.) Figure 3 As shown, the SVI value of sludge in the secondary sedimentation tank was 24 mL / g, indicating that the sludge settling performance was greatly improved.

[0060] 2) Example 2

[0061] Unlike Example 1, this example addresses the increased influent flow and load during the rainy season. The MLSS concentration of the influent wastewater is 4100 mg / L, the COD concentration is 200–215 mg / L, and the NO3 concentration is [not specified]. - The -N concentration was 45–50 mg / L, the pH was 7.4, the magnetic powder used was a 20 μm diameter metal powder, the magnetic induction intensity was 66 emu / g, and the magnetic biocapacitance was 7.5 × 10⁻⁶. -4 F / mL, magnetic powder addition ratio is 1:1.

[0062] The wastewater treatment process was the same as in Example 1, with the mixing tank connected to the anaerobic, anoxic, and aerobic zones, fully utilizing the adsorption properties and carrier effect of the magnetic powder. In the secondary sedimentation tank, the rapid settling of the sludge flocs ensured the system's efficient operation. Experimental results (attached) Figure 4 The results showed that after 28 days, the effluent nitrate concentration was 3.3 mg / L, with a removal rate of 88.6%; the COD concentration was 10 mg / L, with a removal rate of 95.0%. The SVI value of the secondary sedimentation tank sludge was 28 mL / g (see attached image). Figure 5 The settling performance has been further improved.

[0063] 3) Example 3

[0064] This embodiment investigates the treatment efficiency under conditions of low COD and high ammonia nitrogen influent. The influent wastewater had an MLSS concentration of 4100 mg / L, a COD concentration of 180–200 mg / L, and an NH4+ concentration of [missing information]. + The ammonia nitrogen (N-N) concentration was 20 mg / L, and the pH value was 7.6. The magnetic powder used was a 20 μm diameter metal powder with a magnetic induction intensity of 66 emu / g and a magnetic biocapacitance of 8.1 × 10⁻⁶. -4 F / mL, magnetic powder addition ratio is 0.5:1.

[0065] The wastewater treatment process was the same as the previous two examples, but the magnetic powder dosage was lower to suit the low carbon-to-nitrogen ratio influent conditions. Experimental results (attached) Figure 6 This indicates that after 28 days, the effluent NH4... +-N concentration was 0.8 mg / L, with a removal rate of 95.7%; COD concentration was 17.3 mg / L, with a removal rate of 90.5%. The SVI value of the secondary sedimentation tank sludge was 56 mL / g (attached). Figure 7 Although its settling performance is slightly inferior to the previous two examples, it still meets the requirements for efficient treatment.

[0066] This invention utilizes the high density, magnetic properties, and surface microstructure of magnetic powder to construct a highly efficient composite sludge system. This technology enhances the extracellular electron transfer rate between microorganisms and the interaction between magnetic powder and microorganisms, thereby increasing bioelectric capacity and accelerating the conversion of dissolved oxygen (DO), organic matter (COD), and ammonia nitrogen (NH4+). + -N) and nitrates (NO3) - The magnetic powder significantly reduced the reaction rate of substrates such as nitrogen (N-N) and decreased the accumulation of intermediate products. As a core carrier in activated sludge flocs, the magnetic powder optimized sludge settling performance, shortened settling time, and reduced sedimentation tank volume. The introduction of magnetic powder significantly promoted the enrichment and activity of denitrification-related functional microorganisms (such as ammonia-oxidizing bacteria and denitrifying bacteria), further improving biological denitrification efficiency and achieving in-situ quality improvement and efficiency enhancement by optimizing the microbial community structure. Furthermore, the porous structure of the magnetic powder surface allows microorganisms to quickly attach, inhabit, and grow there, while reducing the secretion of extracellular polymeric substances (EPS), thus reducing excess sludge production by more than 30%, effectively lowering sludge treatment and disposal costs.

[0067] This invention also reduces greenhouse gas emissions (such as N2O) at the source during wastewater treatment. By optimizing the extracellular electron transport system and dissolved oxygen utilization, the generation rate of denitrification byproducts by ammonia-oxidizing bacteria under DO-deficient conditions is effectively reduced, resulting in a reduction of N2O emissions by approximately 50%. In traditional activated sludge processes, N2O is the main source of direct carbon emissions from wastewater treatment plants, with a greenhouse effect potential up to 273 times that of CO2. This invention achieves the goal of reducing greenhouse gas emissions at the source through process design, providing a novel technical solution for low-carbon wastewater treatment. By optimizing the microbial community structure and settling properties of activated sludge, this process enhances the sludge system's resistance to shock loads, enabling stable operation under fluctuating water quality and high-risk conditions, while effectively controlling sludge bulking, achieving in-situ quality improvement, efficiency enhancement, and carbon reduction of the system.

[0068] The foregoing descriptions and embodiments are provided to enable those skilled in the art to understand and apply this invention. Those skilled in the art will readily make various modifications to these contents and apply the general principles described herein to other embodiments without inventive effort. Therefore, this invention is not limited to the foregoing descriptions and embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of this invention without departing from its scope should be within the protection scope of this invention.

Claims

1. A wastewater treatment system based on dense magnetic powder-reinforced activated sludge, characterized in that, include: A mixing tank, the inlet of which is used to connect to a pipe for pre-treated wastewater, is equipped with a stirring component to fully mix the wastewater and magnetic powder; A magnetic powder feeding mechanism is used to feed magnetic powder into a mixing tank; The biological reactor includes an anaerobic tank, an anoxic tank, and an aerobic tank connected in sequence. The anaerobic tank is connected to the outlet of the mixing tank. Both the anaerobic tank and the anoxic tank are equipped with stirring components. An aeration pipe is installed at the bottom of the aerobic tank to maintain the stability of dissolved oxygen. The aerobic tank returns nitrified liquid to the anoxic tank through a first nitrification liquid return pipe, a nitrification liquid return pump, and a second nitrification liquid return pipe.

2. The wastewater treatment system according to claim 1, characterized in that, The magnetic powder feeding mechanism is either a dry powder feeding device or a screw + pump device.

3. The wastewater treatment system according to claim 1, characterized in that, The magnetic powder has a particle size of 10–60 μm, and / or The magnetization of the magnetic powder is 30–70 emu / g, and / or The magnetic biocapacitance of the magnetic powder ranges from (5 to 10) × 10⁻⁶. -4 F / mL.

4. The wastewater treatment system according to claim 1, characterized in that, The magnetic powder is spherical or nearly spherical in shape.

5. The wastewater treatment system according to claim 1, characterized in that, It also includes a quantitative control module, which includes a sludge concentration meter, a water level gauge, and a controller. The sludge concentration meter is installed on the inner wall of the mixing tank to detect the sludge content in the wastewater. The water level gauge is used to detect the wastewater level in the mixing tank. The controller is used to receive the sludge content information detected by the sludge concentration meter and the wastewater level information transmitted by the water level gauge, and to calculate the mass of activated sludge in the mixing tank based on these information. The controller is electrically connected to the magnetic powder feeding mechanism to control the amount of magnetic powder added by the magnetic powder feeding mechanism.

6. The system according to claim 5, characterized in that, The sludge concentration meter is model T-BD5CMD-SS4210.

7. The system according to claim 1, characterized in that, The mass ratio of magnetic powder to activated sludge was controlled at 0.5–1.5:

1.

8. The system according to claim 1, characterized in that, It also includes a secondary sedimentation tank for rapid settling of high-density magnetic sludge flocs. The inlet of the secondary sedimentation tank is connected to the outlet of the aerobic tank to allow wastewater from the aerobic tank to flow into the secondary sedimentation tank. The bottom of the secondary sedimentation tank is connected to the mixing tank via a return assembly to allow most of the sludge and magnetic powder mixture to be directly recycled into the mixing tank. The return assembly includes a return sludge pipe I, a return sludge pump, and a return sludge pipe II. One end of the return sludge pipe I is connected to the bottom of the secondary sedimentation tank, and the other end of the return sludge pipe I is connected to the return sludge pump. The return sludge pump is connected to the mixing tank via the return sludge pipe II.

9. The system according to claim 8, characterized in that, The secondary sedimentation tank is also equipped with a magnetic powder recovery component to recover magnetic powder from the sludge. The magnetic powder recovery component includes a residual sludge pipe, a magnetic separation device, and a magnetic powder recovery pipe. One end of the residual sludge pipe is connected to the bottom of the secondary sedimentation tank, and the other end of the residual sludge pipe is connected to the magnetic separation device. The magnetic separation device uses a magnetic field to adsorb and separate the magnetic powder, and collects the magnetic powder through the magnetic powder recovery pipe.

Images