A eutrophication wastewater treatment system and method of use thereof

Abstract

The application discloses a kind of eutrophication sewage treatment systems and its use method, total water inlet is connected with pretreatment unit, biological treatment unit and post-treatment unit in turn, and post-treatment unit is connected with total water outlet;Biological treatment unit includes front-end unit architecture and rear-end unit architecture;Front-end unit architecture is parallelly connected aerobic treatment pool and anaerobic treatment pool;Rear-end unit architecture is anaerobic treatment unit and aerobic treatment unit connected in turn;Anaerobic treatment unit and aerobic treatment unit are both cabinet structure, including processing unit cabinet, one side is equipped with water inlet hole seat, the other side is equipped with water outlet hole seat;Close to water inlet hole seat one side is equipped with volume buffer cavity and flat gate in turn, the other side of flat gate is equipped with multiple horizontal space, horizontal space is connected with water outlet hole seat through water outlet buffer cavity;Flat gate is equipped with flow equalizing device, and flow equalizing device is composed of multiple staggered setting baffle.This application improves the response capability to complex water quality, realizes the effective removal of pollutants.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an eutrophic wastewater treatment system and its usage method. Background Technology

[0002] Eutrophication is a phenomenon characterized by excessive levels of plant nutrients such as nitrogen and phosphorus, leading to the overgrowth of algae and other aquatic plants, resulting in algal blooms or red tides, and consequently, water quality deterioration and ecosystem imbalance. In recent years, human activities have resulted in the discharge of large amounts of industrial wastewater, biological wastewater, and plant nutrients from agricultural runoff into slow-moving water bodies such as lakes, reservoirs, estuaries, and bays. This has altered the biomass, species diversity, and abundance of these bodies, disrupting the ecological balance and leading to an increasing prevalence of eutrophication. Treating eutrophic wastewater is not only a crucial measure for environmental protection but also a key link in achieving sustainable water resource utilization and promoting economic and social development. Effective treatment of eutrophic wastewater can improve water quality, protect ecosystems, reduce environmental risks, enhance public quality of life, and support green economic development and sustainable growth. Therefore, eutrophic wastewater treatment has profound environmental, economic, and social significance.

[0003] Currently, the main technologies for treating eutrophic water bodies include physical, chemical, and biological methods. However, these technologies have limitations in practical applications. Physical methods are often used alone, including sediment dredging, water exchange and dilution, manual algae removal, aeration, and flushing. While these methods can significantly improve water quality in the short term, their long-term effects are not ideal. Furthermore, these methods are complex to operate, involve large-scale engineering, are costly, and may damage benthic ecosystems; improper treatment of dredged sediment can also lead to secondary pollution. Single chemical treatment methods mainly rely on adding chemical reagents (such as aluminum salts, iron salts, calcium salts, and algicides) to remove pollutants from wastewater. However, this method has the problem of reagent residues, which may lead to the risk of secondary pollution of water bodies and have a certain impact on non-target organisms. Although the short-term effects are significant, there are shortcomings in the long term. In addition, it also faces problems such as high operating costs and drug resistance. Biological treatment methods mainly utilize the metabolic processes of microorganisms, plants, or animals to remove pollutants from wastewater. However, their effectiveness is significantly affected by environmental factors. Furthermore, high concentrations of pollutants may inhibit microbial activity, affecting the treatment efficiency of biological treatment technologies. Pretreatment is required, and the methods also suffer from drawbacks such as high maintenance costs and poor adaptability to water quality fluctuations and sudden pollution events.

[0004] Given that single methods are insufficient for efficiently removing multiple pollutants such as nitrogen, phosphorus, and organic matter, and cannot meet the needs of complex water quality treatment or achieve long-term stable water quality improvement, a combination of multiple technologies is currently widely adopted. However, these combined technologies also face challenges in practical applications, including high integration difficulty, high operating costs, and complex management. The biological treatment component, in particular, often employs a structured tank with biological filter media, resulting in relatively low treatment efficiency, high energy consumption that is difficult to control, and a tendency for localized biofilm clogging. Furthermore, the replacement and maintenance of the biological filter media are cumbersome, leading to insufficient uniformity of water treatment within the tank. This results in poor and unstable overall performance of the biological treatment component, and its instability when working in conjunction with other treatment components can easily lead to a decline in the overall system efficiency. This limits its widespread application in eutrophic wastewater treatment. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a eutrophic wastewater treatment system and its usage method. The biological treatment unit employs a front-end aerobic and anaerobic parallel treatment architecture, combined with a back-end anaerobic and aerobic series treatment process, which improves the ability to cope with complex water quality and achieves effective removal of pollutants.

[0006] To achieve the above objectives, the present invention provides an eutrophic wastewater treatment system, wherein the main inlet is sequentially connected to a pretreatment unit, a biological treatment unit, and a post-treatment unit, and the post-treatment unit is connected to the main outlet; the biological treatment unit includes a front-end unit architecture and a back-end unit architecture; the front-end unit architecture consists of a parallel aerobic treatment tank and an anaerobic treatment tank; the back-end unit architecture consists of an anaerobic treatment unit and an aerobic treatment unit connected in series.

[0007] Preferably, both the anaerobic treatment unit and the aerobic treatment unit are cabinet structures, including a treatment unit cabinet. One side of the treatment unit cabinet is provided with a water inlet seat, and the other side is provided with a water outlet seat. Inside the treatment unit cabinet, a volume buffer chamber and a flat gate are arranged in sequence on the side near the water inlet seat. On the other side of the flat gate, there are multiple horizontal flow spaces, which are connected to the water outlet seat through the water outlet buffer chamber.

[0008] More preferably, the flat gate is provided with a flow equalization device; the flow equalization device is composed of multiple staggered partitions; the partitions are provided with multiple through holes.

[0009] More preferably, the through holes are distributed in a plum blossom pattern, with a diameter of 15-25 mm and a spacing of 60-100 mm.

[0010] More preferably, the number of partitions is 3-5.

[0011] More preferably, the advection space is divided by a horizontal partition, which is fixed and limited by a fixed bracket.

[0012] The fixed partitions are evenly fixed on one side wall of the flow equalization device and the outlet buffer chamber near the advection space. Each fixed partition has a fixing component at the bottom for fixing the central rope in the biological packing.

[0013] More preferably, the advection space is provided with a flow guide pipe and an independent treatment unit connected in sequence; the flow guide pipe and the independent treatment unit are provided with biological packing material.

[0014] More preferably, the independent processing unit has a rapidly expanding tube structure, with the diameter at its widest point being 1.5-2.5 times the diameter at its narrowest point, and the diameter at its widest point being equal to the diameter of the guide tube; the biological packing includes a central rope and fiber packing; the fiber packing is fixed on the ring plate and then fixed on the central rope.

[0015] Furthermore, the rapid expansion cavity structure is specifically shaped like an olive, a spindle, or a straight tube, with a larger middle section and smaller ends.

[0016] Preferably, the anaerobic treatment unit is equipped with a first flat gate, an anaerobic sludge return pump and a first ultrasonic sensor at the bottom. When the first ultrasonic sensor detects that the sludge thickness at the bottom of the anaerobic treatment unit exceeds a set threshold, the anaerobic sludge return pump is started and 50%-100% of the sludge in the anaerobic treatment unit is returned to the anaerobic treatment tank. The remaining sludge that is not returned enters the sludge treatment system for concentration, digestion and dewatering.

[0017] Preferably, the aerobic treatment unit is equipped with a second flat gate and a second microporous aerator, and a second ultrasonic sensor and an aerobic sludge return pump at the bottom. When the second ultrasonic sensor detects that the sludge thickness at the bottom of the aerobic treatment unit exceeds a set threshold, the aerobic sludge return pump returns 50%-100% of the sludge in the aerobic treatment unit to the aerobic treatment tank. The remaining sludge that is not returned enters the sludge treatment system for concentration, digestion and dewatering.

[0018] More preferably, the first and second flat gates are either rising or falling flat gates, driven by a screw, hydraulically, or electrically.

[0019] Preferably, a hydraulic cavitation device is provided on the pipeline connecting the anaerobic treatment unit and the aerobic treatment unit.

[0020] More preferably, the hydraulic cavitation device is a Venturi tube or orifice plate HC reactor.

[0021] Preferably, the aerobic treatment tank is equipped with a microporous aerator, a stirring device, and a dissolved oxygen detector; the aerobic treatment unit is equipped with a second microporous aerator.

[0022] More preferably, the dissolved oxygen detector is any one of the following: SIN-DM2800 DO meter, MIK-DY2900 fluorescence dissolved oxygen meter, and SZ-RJYB online dissolved oxygen meter / DO meter; the microporous aerator is any one of the following: suspended chain aerator, membrane microporous aerator, tubular aerator, etc.

[0023] Preferably, the pretreatment unit includes a bar screen and a grit chamber connected in series; the posttreatment unit includes a sand filter, a chemical reaction tank, an activated carbon adsorption tank, and a deep oxidation tank connected in series.

[0024] More preferably, the grid pool is provided with two grids, namely a coarse grid with a spacing of 5-20mm and a fine grid with a spacing of 1-5mm.

[0025] More preferably, the sedimentation tank is a horizontal flow sedimentation tank; the outlet of the sedimentation tank is equipped with a filter cloth filter screen with a pore size of 0.2~0.5mm.

[0026] More preferably, the sand filter is a pressure sand filter, in which water enters from the bottom and exits from the top when the pressure difference is >0.15MPa, and in which water enters from the bottom and exits from the top when the pressure difference is ≤0.15MPa.

[0027] More preferably, the structure of the chemical reaction tank is basically the same as that of a chemical dosing tank or chemical dosing system commonly used in sewage treatment. It is equipped with a stirring device. Coagulants, flocculants and other chemical agents are added from the top of the chemical reaction tank. The coagulated and precipitated substances are periodically discharged through the sludge collection device at the bottom of the chemical reaction tank. The treated water is discharged from the upper part of one side of the chemical reaction tank.

[0028] More preferably, the water in the activated carbon adsorption tank is fed from the top and discharged from the bottom; the deep oxidation tank includes a dosing device and a stirring device, and the water quality is deeply purified by adding a strong oxidant such as chloride.

[0029] Preferably, the pipeline connecting the pretreatment unit and the biological treatment unit is equipped with a water quality analyzer, an inlet regulating valve, and a water pressure regulating pump.

[0030] More preferably, the water quality detector is used to detect the wastewater quality after the pretreatment unit, and then, based on the water quality data, the inlet regulating valve and the water pressure regulating pump are controlled by the control unit connected by communication to control the amount and pressure of water entering the biological treatment unit.

[0031] More preferably, the grit chamber in the pretreatment unit is connected to the aerobic treatment tank and the anaerobic treatment tank respectively; the pipeline connecting the grit chamber and the aerobic treatment tank is equipped with a water quality analyzer, a first inlet regulating valve and a first water pressure regulating pump; the pipeline connecting the grit chamber and the anaerobic treatment tank is equipped with a water quality analyzer, a second inlet regulating valve and a second water pressure regulating pump.

[0032] More preferably, the first and second water pressure regulating pumps are unidirectional fixed displacement hydraulic pumps.

[0033] Preferably, the effluent pipelines of the pretreatment unit, biological treatment unit, and posttreatment unit are equipped with a real-time water quality feedback system; the real-time water quality feedback system includes an online sensor group, which is communicatively connected to the control unit to implement water quality data feedback, and controls the aeration intensity of the microporous aerators connected to the communication unit through a preset algorithm in the control unit, and controls the height of the flat gate, thereby controlling the number of advection spaces activated; the sensor group includes a combination of pH sensor, dissolved oxygen sensor, ammonia nitrogen sensor, and total phosphorus sensor.

[0034] The present invention also provides a method for using an eutrophic wastewater treatment system, comprising the following steps: (1) Eutrophic wastewater enters the treatment system through the main inlet and is physically filtered by the pretreatment unit; (2) After physical filtration, the water quality is tested and the water volume and pressure are adjusted by a water quality tester, an inlet regulating valve and a water pressure regulating pump. The water then enters the biological treatment unit, where it undergoes aerobic treatment and anaerobic treatment, and then passes through the anaerobic treatment unit and aerobic treatment unit in sequence. (3) After the biological treatment is completed, it enters the post-treatment unit for deep oxidation.

[0035] Preferably, when the anaerobic treatment unit and the aerobic treatment unit in step (2) treat wastewater, the activation level of the advection space is adjusted by using a flat gate according to the wastewater load, and the total flow fluctuation range is kept within ±5% by the flow equalization device, and the flow deviation entering each advection space is ≤10%; wherein when the wastewater load is COD 300-500mg / L, 100% of the advection space is activated; when the wastewater load is COD 150-300mg / L, 50%-60% of the advection space is activated; when the wastewater load is COD<150mg / L, 20-30% of the advection space is activated.

[0036] Preferably, in step (2), the influent flow rate of the aerobic treatment tank and the anaerobic treatment tank is 5-20 m³ / h, and the water pressure ranges from 0.2 to 0.6 bar; the aeration intensity of the aerobic treatment tank is 0.8-2.5 m³ / (m²·h), and the dissolved oxygen concentration is controlled at 2-4 mg / L.

[0037] The beneficial effects of this invention are: the modular assembly structure enables independent control of each processing unit, supports rapid on-site replacement or cleaning, reduces downtime and maintenance costs.

[0038] The biological treatment unit features a parallel aerobic and anaerobic treatment tanks at the front end, and a series-connected anaerobic and aerobic treatment units at the rear end. The parallel front-end structure provides initial pretreatment of wastewater, improving treatment efficiency. Furthermore, by adjusting the water flow and pressure at the front end, the system's adaptability to complex water qualities is enhanced, ensuring good overall treatment efficiency under varying water conditions and guaranteeing efficient pollutant removal. The series-connected rear end, with anaerobic treatment preceding aerobic treatment, further enhances the treatment of the water already treated by the front end. This further improves the decomposition of organic matter in the anaerobic unit into simpler substances such as methane and carbon dioxide, removes nitrogen, phosphorus, and other organic compounds from the water, and utilizes the oxidation of ammonia nitrogen by nitrifying bacteria in the aerobic unit, effectively preventing eutrophication. Additionally, by incorporating biological packing modules into the anaerobic and aerobic treatment units at the rear end of the biological treatment unit, favorable conditions are provided for microbial growth and reproduction, improving the efficiency of biological treatment and achieving efficient removal of nitrogen, phosphorus, and organic matter from wastewater. This design also offers advantages such as ease of operation, good operational stability, and low operating costs.

[0039] The diaphragms separate multiple advection spaces within the anaerobic and aerobic treatment units. At the front end, flat gates and flow equalization devices regulate and equalize the wastewater load, ensuring uniform water distribution within the advection spaces. This reduces turbulence and eddies, preventing excessively high or low local velocities, thereby improving the overall treatment efficiency and operational stability of the anaerobic and aerobic units. The shape of the diaphragms creates independent treatment units with outward-expanding cavities, enhancing fluid turbulence and facilitating the uniform distribution of biological packing material. Furthermore, the staggered distribution of these independent units increases the density of the biological packing material, providing a sufficient and ideal habitat for microbial growth and reproduction, thus improving biological treatment efficiency. The detachable structure of the diaphragms facilitates maintenance and repair. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0041] Figure 2 This is a schematic diagram of the overall structure of the biological treatment unit.

[0042] Figure 3 This is a schematic diagram of the overall structure of the optimized biological treatment unit.

[0043] Figure 4This is a schematic diagram of the aerobic treatment unit.

[0044] Figure 5 This is a schematic diagram of the structure of advection space.

[0045] Figure 6 This is a schematic diagram of the structure of the biological packing material. In the diagram, A is a schematic diagram of the overall structure, and B is a schematic diagram of the structure of the ring plate.

[0046] In the diagram, 1 is the main inlet, 2 is the pretreatment unit, 3 is the biological treatment unit, 4 is the post-treatment unit, 5 is the bar screen, 501 is the coarse bar, 502 is the fine bar, 6 is the grit chamber, 7 is the aerobic treatment tank, 701 is the first inlet regulating valve, 702 is the first water pressure regulating pump, 703 is the stirring device, 704 is the first microporous aerator, 8 is the anaerobic treatment tank, 801 is the second inlet regulating valve, 802 is the second water pressure regulating pump, 9 is the anaerobic treatment unit, 901 is the first flat gate, 902 is the first ultrasonic sensor, 903 is the anaerobic sludge return pump, 10 is the aerobic treatment unit, 101 is the second flat gate, and 102 is the second ultrasonic sensor. Wave sensor, 103 aerobic sludge return pump, 104 second microporous aerator, 11 sand filter, 12 chemical reaction tank, 13 activated carbon adsorption tank, 14 deep oxidation tank, 15 main outlet, 16 water quality analyzer, 17 inlet port seat, 18 volumetric buffer chamber, 19 flow equalization device, 20 treatment unit cabinet, 21 horizontal flow space, 22 horizontal partition, 211 flow guide pipe, 212 independent treatment unit, 23 fixed partition, 24 biological packing, 241 central rope, 242 ring plate, 243 fiber packing, 25 hydraulic cavitation device, 26 sludge treatment system, 27 outlet port seat. Detailed Implementation

[0047] The technical solution of the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0048] Example 1 like Figure 1-6As shown, an eutrophic wastewater treatment system has a main inlet 1 connected sequentially to a pretreatment unit 2, a biological treatment unit 3, and a post-treatment unit 4. The post-treatment unit 4 is connected to a main outlet 15. Eutrophic wastewater enters the system through the main inlet 1 and undergoes physical filtration in the pretreatment unit 2 to remove impurities, large particles larger than 0.5 mm, and suspended solids. After pretreatment, the wastewater enters the biological treatment unit 3 for aerobic and anaerobic treatment. Following this, the wastewater enters the post-treatment unit 4, where residual pollutants are further removed through physical adsorption and chemical oxidation to improve the effluent quality. Finally, the treated water flows out through the main outlet 16, completing the treatment of the eutrophic wastewater. The biological treatment unit 3... The system includes a front-end unit architecture and a back-end unit architecture. The front-end unit architecture consists of a parallel aerobic treatment tank 7 and an anaerobic treatment tank 8, which respectively treat wastewater aerobicly and anaerobicly. This provides pretreatment for the wastewater entering the biological treatment unit 3, improving treatment efficiency and the system's adaptability to complex water qualities. It also allows for flexible adjustment of the treatment load based on actual water quality conditions, ensuring efficient removal of pollutants. The back-end unit architecture consists of an anaerobic treatment unit 9 and an aerobic treatment unit 10 connected in series, which sequentially treat wastewater anaerobicly and aerobically, further enhancing the treatment effect and converting organic pollutants in the wastewater into simple, harmless substances such as carbon dioxide, water, or methane.

[0049] Preferably, both the anaerobic treatment unit 9 and the aerobic treatment unit 10 are enclosed cabinet structures, including a treatment unit cabinet 20. One side of the treatment unit cabinet 20 has an inlet seat 17, and the other side has an outlet seat 27 for wastewater inflow and outflow. Inside the treatment unit cabinet 20, near the inlet seat 17, a volumetric buffer chamber 18 and a flat gate are sequentially arranged. On the other side of the flat gate, multiple horizontal flow spaces 21 are provided. The horizontal flow spaces 21 are connected to the outlet seat 27 via the outlet buffer chamber. The volumetric buffer chamber 18 is used to buffer the wastewater entering the treatment unit cabinet 20, reducing the impact force. The wastewater entering the treatment unit cabinet 20 then passes through the flat gate to adjust the load before entering the horizontal flow spaces 21 for treatment. The treated wastewater is collected in the outlet buffer chamber and then discharged through the outlet seat 27 to enter the next treatment process.

[0050] Further preferably, the flat gate is equipped with a flow equalization device 19; the flow equalization device 19 is composed of multiple staggered baffles; the baffles are provided with multiple through holes, and the sewage after the load is adjusted by the flat gate is optimized for flow characteristics by the flow equalization device 19, so that the sewage flow rate entering each advection space 21 is evenly distributed, the flow rate deviation is ≤10%, and the total flow rate fluctuation range is ±5%, which reduces the generation of turbulence or eddies, avoids local flow velocities that are too high or too low, thereby improving the overall treatment efficiency of the corresponding aerobic treatment unit 10 or anaerobic treatment unit 9.

[0051] More preferably, the through holes are distributed in a plum blossom pattern, with a diameter of 15-25 mm and a spacing of 60-100 mm.

[0052] More preferably, the number of partitions is 3-5.

[0053] In a further preferred embodiment, the advection space 21 is divided by a horizontal partition 22, which is fixed and limited by a fixed bracket 23. The horizontal partition 22 is placed on the fixed bracket 23 to divide the space after the flow equalization device 19 into multiple advection spaces 21 for independent treatment of the water.

[0054] More preferably, the fixed partitions 23 are evenly fixed on one side wall of the flow equalization device 19 and the outlet buffer chamber near the advection space 21, forming a fixed assembly for fixing and limiting the position of the transverse partitions 22. At the same time, the transverse partitions 22 placed on the fixed partitions 23 can be pulled out for cleaning and maintenance, and the corresponding advection space 21 can also be exposed for maintenance. Each fixed partition 23 has a fixing piece at its bottom for fixing the central rope 241 in the biological packing 24.

[0055] More preferably, the diaphragm 22 is a directly formed structure corresponding to the flow guide pipe 211 and the independent processing unit 212, so that two adjacent diaphragms 22 can be combined to form an independent processing unit 212 with an outwardly expanded cavity structure and a flow guide pipe 211 connected in sequence to form a flow space 21.

[0056] Furthermore, the top of the diaphragm 22 is provided with Φ10mm ventilation holes, spaced 150mm apart in a quincunx pattern, and is equipped with a gas guide channel (20mm deep, 30mm wide) to ensure uniform aeration.

[0057] More preferably, the advection space 21 is provided with a flow guide pipe 211 and an independent treatment unit 212 connected in sequence; the flow guide pipe 211 and the independent treatment unit 212 are provided with biological packing material 24, which can independently treat the water.

[0058] More preferably, the independent processing unit 212 has a rapid expansion cavity structure, with the diameter at its widest point being 1.5-2.5 times the diameter at its narrowest point, and the diameter at its widest point being equal to the diameter of the guide pipe; the biological packing material 24 includes a central rope 241 and a fiber packing material 243; the fiber packing material 243 is fixed on the ring plate 242 and then fixed on the central rope 241.

[0059] Furthermore, the rapid expansion cavity structure is specifically shaped like an olive, a spindle, or a straight tube, with a larger middle section and smaller ends.

[0060] Furthermore, within each advection space 21, the independent treatment units 212 are arranged in a staggered manner, which increases the arrangement density of the biological packing material 24 in the entire treatment unit cabinet 20, while optimizing the fluid short-circuiting phenomenon between layers, ensuring that the sewage can fully contact the biological packing material, thereby improving the biological treatment efficiency.

[0061] Preferably, the anaerobic treatment unit 9 is equipped with a first flat gate 901 inside, and an anaerobic sludge return pump 903 and a first ultrasonic sensor 902 at the bottom. When the first ultrasonic sensor 902 detects that the sludge thickness at the bottom of the anaerobic treatment unit 9 exceeds a set threshold, the anaerobic sludge return pump 903 starts and returns 50%-100% of the sludge in the anaerobic treatment unit 9 to the anaerobic treatment tank 8. The remaining sludge that is not returned enters the sludge treatment system 26 for concentration, digestion and dewatering.

[0062] More preferably, the threshold value for the sludge thickness is 3-8 mm.

[0063] Preferably, the aerobic treatment unit 10 is equipped with a second flat gate 101 and a second microporous aerator 104, and a second ultrasonic sensor 102 and an aerobic sludge return pump 103 at the bottom. When the second ultrasonic sensor 102 detects that the sludge thickness at the bottom of the aerobic treatment unit 10 exceeds a set threshold, the aerobic sludge return pump 103 returns 50%-100% of the sludge in the aerobic treatment unit 10 to the aerobic treatment tank 7. The remaining sludge that is not returned enters the sludge treatment system 26 for concentration, digestion and dewatering.

[0064] More preferably, the threshold value for the sludge thickness is 3-8 mm.

[0065] More preferably, the bottom of the anaerobic treatment unit 9 and the aerobic treatment unit 10 is provided with a V-shaped sludge trough with an opening angle of 60° and a depth of 50mm. An adjustable weir gate is installed in the trough with an adjustment range of 20-50mm to facilitate sludge settling and return.

[0066] More preferably, the first flat gate 901 and the second flat gate 101 are either rising or falling flat gates, driven by a screw, hydraulically, or electrically. The gate height can be adjusted by controlling the sewage load, thereby regulating the number of open horizontal flow spaces 21. Specifically, when the sewage load is COD 300-500 mg / L, 100% of the horizontal flow space is activated; when the sewage load is COD 150-300 mg / L, 50%-60% of the horizontal flow space is activated; and when the sewage load is COD < 150 mg / L, 20-30% of the horizontal flow space is activated.

[0067] Preferably, a hydraulic cavitation device 25 is provided on the pipeline connecting the anaerobic treatment unit 9 and the aerobic treatment unit 10. The hydraulic cavitation device 25 can generate microbubbles, reduce aeration energy consumption, and at the same time, the rising microbubbles will drive the water flow, enhance water disturbance, promote full contact between microorganisms and pollutants, and further improve biological treatment efficiency. In addition, the hydraulic cavitation effect can also generate a local temperature and high pressure environment, which is conducive to the decomposition of recalcitrant organic matter, prevent pipeline blockage, and make it more adaptable and efficient in treating complex eutrophic water bodies.

[0068] More preferably, the hydraulic cavitation device 25 is a venturi tube or orifice plate HC reactor.

[0069] Preferably, the aerobic treatment tank 7 is equipped with a microporous aerator 704, a stirring device 703 and a dissolved oxygen detector to provide an aerobic environment and promote the growth and reproduction of aerobic microorganisms; the aerobic treatment unit 10 is equipped with a second microporous aerator 104 to provide an aerobic environment and promote the growth and reproduction of aerobic microorganisms.

[0070] More preferably, the dissolved oxygen detector is any one of the following: SIN-DM2800 DO meter, MIK-DY2900 fluorescence dissolved oxygen meter, and SZ-RJYB online dissolved oxygen meter / DO meter; the microporous aerator is any one of the following: suspended chain aerator, membrane microporous aerator, tubular aerator, etc.

[0071] Preferably, the pretreatment unit 2 includes a screen tank 5 and a grit chamber 6 connected in series to perform pre-filtration of eutrophic wastewater, removing impurities, large particles with a diameter greater than 0.5 mm, and suspended solids, thus preventing blockage of subsequent treatment units and connecting pipelines; the post-treatment unit 4 includes a sand filter tank 11, a chemical reaction tank 12, an activated carbon adsorption tank 13, and a deep oxidation tank 14 connected in series to perform secondary filtration and deep oxidation of wastewater, thereby improving water quality.

[0072] More preferably, the grit chamber 5 is provided with two grit chambers, namely a coarse grit chamber with a spacing of 5-20mm and a fine grit chamber with a spacing of 1-5mm, which are used to intercept larger suspended matter and remove smaller particulate matter, respectively, to ensure that particulate matter in the sewage entering the grit chamber is effectively removed.

[0073] More preferably, the sedimentation tank 6 is a horizontal flow sedimentation tank; the outlet of the sedimentation tank 6 is equipped with a filter cloth with a pore size of 0.2-0.5mm, which removes heavier inorganic particles through gravity sedimentation, reducing the burden on subsequent treatment units; the filter cloth serves as the last physical filtration barrier, further refining the filtration effect and ensuring that the water quality of the pretreatment unit meets the requirements of the subsequent biological treatment unit.

[0074] More preferably, the sand filter 11 is a pressure sand filter. When the pressure difference is >0.15MPa, the water enters from the bottom and exits from the top; when the pressure difference is ≤0.15MPa, the water enters from the bottom and exits from the top. When the raw water enters the sand filter through the inlet pipe, it first enters the support layer, where larger particles are initially intercepted. Subsequently, the water flows through the quartz sand layer, utilizing the pores and gaps between the quartz sand particles to intercept and adsorb suspended solids, particles, and organic matter in the water. This process is similar to filtering out larger particles through a sieve. At the same time, the fine pores can further block smaller particles and suspended solids, achieving deep filtration.

[0075] More preferably, the structure of the chemical reaction tank 12 is basically the same as that of a chemical dosing tank or chemical dosing system commonly used in sewage treatment. It is equipped with a stirring device. Coagulants, flocculants, and other chemical agents are added from the top of the chemical reaction tank 12. The coagulated and precipitated substances are periodically discharged through a sludge collection device at the bottom of the chemical reaction tank 12, and the treated water is discharged from the upper part of one side of the chemical reaction tank 12. For example, by adding flocculants such as PAC or PAM to react with water to generate flocculated precipitates, which adsorb suspended impurities in the water, and then using flocculants to help the flocculated precipitates settle, solid-liquid separation is achieved. Simultaneously, the stirring device helps the added flocculants mix quickly and evenly with the water, fully flocculating suspended impurities.

[0076] More preferably, the water in the activated carbon adsorption tank 13 is fed from top to bottom, utilizing the strong physical adsorption capacity of activated carbon to effectively adsorb organic pollutants in wastewater. Furthermore, during the activation process, oxygen-containing functional groups, such as carboxyl groups (-COOH), hydroxyl groups (-OH), and carbonyl groups, are formed on the non-crystalline parts of the activated carbon surface, giving the activated carbon certain chemical adsorption and catalytic oxidation and reduction properties. This effectively removes some metal ions from the wastewater and removes suspended impurities that were not completely flocculated in the reagent reaction tank 12. The deep oxidation tank 14 includes a dosing device and a stirring device. Water quality can be deeply purified by adding strong oxidants such as chlorides; alternatively, photochemical oxidation (semiconductor catalysts are added through a dosing device, mixed evenly, and then irradiated with an ultraviolet light source), catalytic wet oxidation (catalysts are added and mixed through a dosing and stirring device, and a high-temperature and high-pressure environment is maintained with a heating and pressurizing device to oxidize and decompose wastewater), Fenton oxidation (iron salts and hydrogen peroxide are added through a dosing device, and after mixing with a stirring device, pollutants are oxidized and degraded), or Fenton-like methods can be used to deeply oxidize water bodies and purify water quality.

[0077] Preferably, the pipeline connecting the pretreatment unit 2 and the biological treatment unit 3 is equipped with a water quality analyzer 16, an inlet regulating valve, and a water pressure regulating pump to perform water quality testing on the wastewater treated by the pretreatment unit 2 and to regulate the amount and pressure of water entering the biological treatment unit 3.

[0078] More preferably, the water quality detector 16 is used to detect the wastewater quality after treatment by the pretreatment unit 2, and then, based on the water quality data, the inlet regulating valve and the water pressure regulating pump are controlled by the control unit connected by communication to control the amount and pressure of water entering the biological treatment unit 3.

[0079] More preferably, the grit chamber 6 in the pretreatment unit 2 is connected to the aerobic treatment tank 7 and the anaerobic treatment tank 8 respectively; a water quality analyzer 16, a first inlet regulating valve 701 and a first water pressure regulating pump 702 are provided on the pipeline connecting the grit chamber 6 and the aerobic treatment tank 7; a water quality analyzer 16, a second inlet regulating valve 801 and a second water pressure regulating pump 802 are provided on the pipeline connecting the grit chamber 6 and the anaerobic treatment tank 8.

[0080] More preferably, the first water pressure regulating pump 702 and the second water pressure regulating pump 802 are unidirectional fixed displacement hydraulic pumps.

[0081] Preferably, the effluent pipelines of the pretreatment unit 2, biological treatment unit 3, and posttreatment unit 4 are equipped with a real-time water quality feedback system; the real-time water quality feedback system includes an online sensor group, which is connected to the control unit to provide real-time feedback of water quality data, and controls the aeration intensity of the microporous aerator connected to the control unit through a preset algorithm, and controls the height of the flat gate, thereby controlling the number of advection spaces 21 that are activated; the sensor group includes a combination of pH sensor, dissolved oxygen sensor, ammonia nitrogen sensor, and total phosphorus sensor.

[0082] Example 2 An eutrophic wastewater treatment system as described in Example 1 was constructed to treat wastewater originating from an eutrophic river in a suburban area of ​​Hunan Province. The wastewater had an ammonia nitrogen content of 8.2 mg / L, a total phosphorus content of 1.8 mg / L, a COD content of 120 mg / L, and an algal density of 1.5 × 10⁻⁶. 6 -2.5×10 6 The water volume is measured in cells / mL, and the water transparency is 0.3-0.5m. (1) Eutrophic wastewater enters the treatment system through the main inlet 1 and is physically filtered by the pretreatment unit 2; (2) After physical filtration, the water quality is tested and the water flow and pressure are adjusted by the water quality tester 16, the inlet regulating valve and the water pressure regulating pump, and then the water enters the biological treatment unit. It then enters the aerobic treatment tank 7 and the anaerobic treatment tank 8 respectively, and then passes through the anaerobic treatment unit 9 and the aerobic treatment unit 10 in sequence; the water flow entering the aerobic treatment tank 7 is 15m³. 3 The water pressure is 0.4 bar, and the volume of water entering anaerobic treatment tank 8 is 15 m³. 3The water pressure is 0.3 bar, and 40% of the advection space 21 is activated in the anaerobic treatment unit 9 and the aerobic treatment unit 10. (3) After the biological treatment is completed, the wastewater enters the post-treatment unit 4 for deep oxidation. In the reagent reaction tank 12 of the post-treatment unit 4, PAC 50mg / L + PAM 0.5mg / L are added, and sodium hypochlorite is added to the deep oxidation tank 14 to further oxidize the wastewater and remove pollutants.

[0083] After 30 days of treatment of eutrophic rivers using the above methods, the ammonia nitrogen content in the water decreased to 1.5 mg / L, the total phosphorus content decreased to 0.4 mg / L, and the COD content decreased to 30 mg / L; algae density decreased by 80%, and water transparency increased to 1.2 meters. The treated eutrophic wastewater can be directly discharged into the river, used for farmland irrigation, or sent to a domestic sewage treatment plant for further purification. The purification process effectively reduces the operational burden on related equipment, improving operational stability and reliability, and extending its service life.

Claims

1. A eutrophic wastewater treatment system, characterized in that: The main inlet (1) is connected in sequence to the pretreatment unit (2), the biological treatment unit (3), and the post-treatment unit (4), and the post-treatment unit (4) is connected to the main outlet (15); the biological treatment unit (3) includes a front-end unit architecture and a back-end unit architecture; the front-end unit architecture consists of a parallel aerobic treatment tank (7) and an anaerobic treatment tank (8); the back-end unit architecture consists of an anaerobic treatment unit (9) and an aerobic treatment unit (10) connected in series. Both the anaerobic treatment unit (9) and the aerobic treatment unit (10) are cabinet structures, including a treatment unit cabinet (20). The treatment unit cabinet (20) has an inlet seat (17) on one side and an outlet seat (27) on the other side. The treatment unit cabinet (20) has a volume buffer chamber (18) and a flat gate on the side near the inlet seat (17). The flat gate has multiple horizontal flow spaces (21) on the other side. The horizontal flow spaces (21) are connected to the outlet seat (27) through the outlet buffer chamber. The advection space (21) is divided by a horizontal partition (22), which is fixed and limited by a fixed bracket (23); the advection space (21) is provided with a flow guide pipe (211) and an independent treatment unit (212) connected in sequence; biological packing material (24) is provided in the flow guide pipe (211) and the independent treatment unit (212). The independent processing unit (212) has a fast-expanding cavity structure, with the diameter at the widest point being 1.5-2.5 times the diameter at the narrowest point, and the diameter at the widest point being equal to the diameter of the guide pipe.

2. The eutrophic wastewater treatment system according to claim 1, characterized in that: The flat gate is equipped with a flow equalization device (19); the flow equalization device (19) is composed of multiple staggered partitions; the partitions are provided with multiple through holes.

3. The eutrophic wastewater treatment system according to claim 1, characterized in that: The biological filler (24) includes a central rope (241) and a fiber filler (243); the fiber filler (243) is fixed on the ring plate (242) and then fixed on the central rope (241).

4. The eutrophic wastewater treatment system according to claim 1, characterized in that: The pretreatment unit (2) includes a grid tank (5) and a grit chamber (6) connected in series; the posttreatment unit (4) includes a sand filter (11), a reagent reaction tank (12), an activated carbon adsorption tank (13), and a deep oxidation tank (14) connected in series.

5. The eutrophic wastewater treatment system according to claim 1, characterized in that: The pipeline connecting the pretreatment unit (2) and the biological treatment unit (3) is equipped with a water quality tester (16), an inlet regulating valve, and a water pressure regulating pump.

6. A method of using an eutrophic wastewater treatment system as described in any one of claims 1-5, characterized in that: Includes the following steps: (1) Eutrophic wastewater enters the treatment system through the main inlet (1) and is physically filtered by the pretreatment unit (2); (2) After physical filtration, the water quality is tested and the water volume and pressure are adjusted by the water quality tester (16), the inlet regulating valve and the water pressure regulating pump. Then the water enters the biological treatment unit and undergoes aerobic treatment and anaerobic treatment respectively. After that, it goes through anaerobic treatment and aerobic treatment in sequence. (3) After the biological treatment is completed, it enters the post-treatment unit (4) for deep oxidation.

7. The method of use according to claim 6, characterized in that: During the sequential anaerobic and aerobic treatment, the activation level of the advection space (21) is adjusted using a flat gate according to the wastewater load. The total flow fluctuation range is kept within ±5% by the flow equalization device (19), and the flow deviation entering each advection space (21) is ≤10%. Specifically, when the wastewater load is COD 300-500mg / L, 100% of the advection space is activated; when the wastewater load is COD 150-300mg / L, 50%-60% of the advection space is activated; and when the wastewater load is COD<150mg / L, 20-30% of the advection space is activated.

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