Eutrophication sewage treatment system and use method thereof

Abstract

The invention discloses a eutrophic sewage treatment system and a use method thereof, a main water inlet is sequentially connected with a pretreatment unit, a biological treatment unit and a post-treatment unit, and the post-treatment unit is connected with a main water outlet; the biological treatment unit comprises a front-end unit framework and a rear-end unit framework; the framework of the front-end unit comprises an aerobic treatment tank and an anaerobic treatment tank which are connected in parallel; the rear-end unit architecture comprises an anaerobic treatment unit and an aerobic treatment unit which are sequentially connected in series; each of the anaerobic treatment unit and the aerobic treatment unit is of a cabinet structure and comprises a treatment unit cabinet, one side of the treatment unit cabinet is provided with a water inlet hole seat, and the other side of the treatment unit cabinet is provided with a water outlet hole seat; a volume buffer cavity and a flat gate are sequentially arranged on one side close to the water inlet hole seat, a plurality of advection spaces are arranged on the other side of the flat gate, and the advection spaces are connected with the water outlet hole seat through a water outlet buffer cavity; and a flow equalizing device is arranged in the flat gate and consists of a plurality of partition plates which are arranged in a staggered manner. According to the invention, the capability of coping with complex water quality is improved, and effective removal of pollutants is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a eutrophic sewage treatment system and a method for using the same. Background Art

[0002] Eutrophication is a phenomenon in which excessive levels of plant nutrients such as nitrogen and phosphorus lead to excessive growth of algae and other aquatic plants, resulting in "algal blooms" or "red tides," which in turn deteriorate water quality and disrupt ecosystem balance. In recent years, human activities have discharged large amounts of industrial wastewater, biogenic wastewater, and plant nutrients from agricultural runoff into slow-flowing water bodies such as lakes, reservoirs, estuaries, and bays. This has altered the biomass and species counts, disrupting the ecological balance of these water bodies and leading to an increasing incidence of eutrophication. Treatment of eutrophic wastewater is not only an important measure for environmental protection but also a key component 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 a green economy and sustainable development. Therefore, eutrophic wastewater treatment has far-reaching environmental, economic, and social significance.

[0003] Current treatment technologies for eutrophic water bodies primarily include physical, chemical, and biological methods. However, these technologies have varying degrees of limitations in practical application. Physical methods are often used in isolation, including sediment dredging, water exchange and dilution, artificial algae harvesting, aeration and oxygenation, and water diversion for flushing. While these methods can significantly improve water quality in the short term, they are not ideal in the long term. Furthermore, these methods are complex, labor-intensive, and costly, and can damage benthic ecosystems. Improper post-dredging sediment treatment can also lead to secondary pollution. Single chemical treatment methods primarily rely on the addition of chemical reagents (such as aluminum salts, iron salts, calcium salts, and algaecides) to remove pollutants from wastewater. However, this approach carries the risk of residual chemicals, leading to the risk of secondary water pollution and impacts on non-target organisms. While effective in the short term, they present limitations in the long term. Furthermore, these methods face challenges such as high operating costs and the development of antibiotic resistance. Biological treatment mainly utilizes the metabolic effects of microorganisms, plants or animals to remove pollutants from sewage. Its treatment effectiveness is significantly affected by environmental factors. At the same time, high concentrations of pollutants may inhibit microbial activity and affect the treatment effect of biological treatment technology. Pretreatment is required, and there are also defects such as high maintenance costs and poor adaptability to water quality fluctuations and sudden pollution incidents.

[0004] Given that a single method is difficult to efficiently remove multiple pollutants such as nitrogen, phosphorus, and organic matter, it cannot meet the needs of complex water quality treatment and it is difficult to achieve long-term and stable water quality improvement. Currently, a treatment strategy combining multiple technologies is generally adopted. However, these combined technologies also face challenges in practical applications, such as difficulty in technical integration, high operating costs, and complex management. In particular, in the biological treatment part, existing technologies mostly use a structural tank body plus biological filter material to construct it. Its treatment efficiency is relatively low, energy consumption is high and difficult to control, and it is also prone to local biofilm blockage. The replacement and maintenance of biological filter materials are also relatively cumbersome, resulting in insufficient uniformity in water treatment in the tank body, resulting in poor and unstable overall effect of the biological treatment part, and poor stability when working in conjunction with other treatment parts, which easily leads to a decrease in the efficiency of the entire treatment system, which limits its widespread application in eutrophic wastewater treatment. Summary of the Invention

[0005] In response to the above technical problems, the present invention provides a eutrophic sewage treatment system and a method for using the same. The system adopts a front-end aerobic and anaerobic parallel treatment architecture in the biological treatment unit, combined with a back-end anaerobic and aerobic series treatment process, thereby improving the ability to cope with complex water quality and achieving effective removal of pollutants.

[0006] In order to achieve the above-mentioned objectives, the present invention provides a eutrophic sewage treatment system, wherein the total water inlet is connected to the pretreatment unit, the biological treatment unit and the post-treatment unit in sequence, and the post-treatment unit is connected to the total water outlet; the biological treatment unit includes a front-end unit architecture and a back-end unit architecture; the front-end unit architecture is an aerobic treatment tank and an anaerobic treatment tank connected in parallel; the back-end unit architecture is composed of an anaerobic treatment unit and an aerobic treatment unit connected in series in sequence.

[0007] Preferably, the anaerobic treatment unit and the aerobic treatment unit are both cabinet structures, including a treatment unit cabinet, with a water inlet seat on one side of the treatment unit cabinet and a water outlet seat on the other side; a volume buffer chamber and a flat gate are sequentially provided on one side of the treatment unit cabinet close to the water inlet seat, and a plurality of horizontal flow spaces are provided on the other side of the flat gate, and the horizontal flow spaces are connected to the water outlet seat through the water outlet buffer chamber.

[0008] Further preferably, a flow balancing device is provided in the flat gate; the flow balancing device is composed of a plurality of staggered partitions; and a plurality of through holes are provided on the partitions.

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

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

[0011] Further preferably, the horizontal flow space is divided by a transverse partition, and the transverse partition is fixed and limited by a fixed partition frame.

[0012] The fixed partitions are evenly fixed on a side wall of the flow equalizing device and the water outlet buffer chamber close to the horizontal flow space. A fixing piece is provided at the bottom of each fixed partition for fixing the central rope in the biological filler.

[0013] More preferably, the horizontal flow space is provided with a diversion pipeline and an independent processing unit connected in sequence; and biological fillers are provided in the diversion pipeline and the independent processing unit.

[0014] More preferably, the independent processing unit is a fast-expanding tubular structure, the diameter at the widest point is 1.5-2.5 times the diameter at the narrowest point, and the diameter at the narrowest point is equal to the diameter of the diversion pipeline; the biological filler includes a central rope and a fiber filler; the fiber filler is fixed on the ring sheet and then fixed on the central rope.

[0015] Furthermore, the rapid expansion lumen structure is specifically olive-shaped, spindle-shaped or straight-tube-shaped, with a large middle and small ends.

[0016] Preferably, a first flat gate is provided inside the anaerobic treatment unit, and an anaerobic sludge return pump and a first ultrasonic sensor are provided 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, and the remaining sludge that is not returned enters the sludge treatment system for concentration, digestion and dehydration treatment.

[0017] Preferably, a second flat gate and a second microporous aerator are provided inside the aerobic treatment unit, and a second ultrasonic sensor and an aerobic sludge return pump are provided 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, and the remaining sludge that is not returned enters the sludge treatment system for concentration, digestion and dehydration.

[0018] Further preferably, the first flat gate and the second flat gate are rising flat gates or descending flat gates, and are driven by any one of screw drive, hydraulic drive and electric drive.

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

[0020] Further preferably, the hydrodynamic cavitation device is a venturi tube or a perforated plate HC reactor.

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

[0022] Further preferably, the dissolved oxygen detector is any one of the LianCe_SIN-DM2800 DO meter, the fluorescence dissolved oxygen tester MIK-DY2900, and the SZ-RJYB online dissolved oxygen meter / DO meter; the microporous aerator is any one of a suspended chain aerator, a diaphragm microporous aerator, a tubular aerator, and the like.

[0023] Preferably, the pretreatment unit includes a grid tank and a grit tank connected in series in sequence; the post-treatment unit includes a sand filter tank, a reagent reaction tank, an activated carbon adsorption tank and a deep oxidation tank connected in series in sequence.

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

[0025] Further preferably, the grit chamber is a horizontal flow grit chamber; the water outlet of the grit chamber is provided with a filter cloth screen with a pore size of 0.2~0.5mm.

[0026] Further preferably, the sand filter is a pressure sand filter, and when the pressure difference is greater than 0.15 MPa, water enters from the bottom and exits from the top; when the pressure difference is less than or equal to 0.15 MPa, water enters from the bottom and exits from the top.

[0027] Further preferably, the structure of the reagent reaction tank is basically the same as the structure of the dosing tank or sewage treatment dosing system commonly used in sewage treatment, and is provided with a stirring device. Chemical agents such as coagulants and coagulant aids are added from the top of the reagent reaction tank, and the condensed and precipitated substances are regularly discharged through the sludge collection device at the bottom of the reagent reaction tank, and the treated water is discharged from the upper part of one side of the reagent reaction tank.

[0028] Further preferably, the water in the activated carbon adsorption tank enters from the top and exits from the bottom; the deep oxidation tank includes a dosing device and a stirring device, and deeply purifies the water quality by adding a strong oxidant such as chloride.

[0029] Preferably, a water quality detector, a water inlet regulating valve and a water pressure regulating pump are provided on the pipeline connecting the pretreatment unit and the biological treatment unit.

[0030] Further preferably, the water quality detector is used to detect the water quality of the sewage after being treated by the pretreatment unit, and then according to the water quality data, the water 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] Further 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 provided with a water quality detector, a first water inlet regulating valve and a first water pressure regulating pump; the pipeline connecting the grit chamber and the anaerobic treatment tank is provided with a water quality detector, a second water inlet regulating valve and a second water pressure regulating pump.

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

[0033] Preferably, a real-time water quality feedback system is provided on the outlet pipelines of the pretreatment unit, the biological treatment unit and the post-treatment unit; the real-time water quality feedback system includes an online sensor group, which is communicatively connected to the control unit to implement feedback of water quality data, and controls the aeration intensity of the microporous aerator connected thereto through an algorithm preset in the control unit, and controls the height of the flat gate, thereby controlling the number of activated horizontal flow spaces; the sensor group includes a combination of a pH sensor, a dissolved oxygen sensor, an ammonia nitrogen sensor and a total phosphorus sensor.

[0034] The present invention also provides a method for using the eutrophication sewage treatment system, comprising the following steps: (1) Eutrophic wastewater enters the treatment system through the main water inlet and is physically filtered through the pretreatment unit; (2) After physical filtration, the water passes through a water quality detector, a water inlet regulating valve, and a water pressure regulating pump to detect and adjust the water volume and pressure, and then enters the biological treatment unit, undergoes aerobic treatment tanks and anaerobic treatment tanks, and then passes through the anaerobic treatment unit and aerobic treatment unit in sequence; (3) After biological treatment, the product enters the post-treatment unit for deep oxidation.

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

[0036] Preferably, the water inlet flow rate of the aerobic treatment tank and the anaerobic treatment tank in step (2) is 5-20 m³ / h, and the water pressure range is 0.2-0.6 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 the present invention are: adopting a modular assembly structure to achieve independent control of each processing unit, supporting rapid on-site replacement or cleaning, reducing downtime for maintenance, and lowering maintenance costs.

[0038] The biological treatment unit features a front-end aerobic and anaerobic treatment tanks connected in parallel, while the back-end anaerobic and aerobic treatment units are connected in series. The parallel front-end structure allows for a pre-treatment of the wastewater, improving treatment efficiency. Furthermore, by adjusting the volume and pressure of water entering the front-end, the system's adaptability to complex water qualities is enhanced, ensuring good overall treatment efficiency under varying water quality conditions and ensuring efficient pollutant removal. The back-end series structure, with anaerobic treatment in the front and aerobic in the back, further enhances the treatment of the water treated by the front-end structure. This further enhances the decomposition of organic matter in the anaerobic treatment unit into simpler substances such as methane and carbon dioxide, removing organic compounds such as nitrogen and phosphorus from the water, and the oxidation of ammonia nitrogen by nitrifying bacteria in the aerobic treatment unit, effectively preventing excessive eutrophication of the water. Furthermore, by incorporating biological filler treatment modules into the anaerobic and aerobic treatment units at the back end of the biological treatment unit, favorable conditions are created for the growth and reproduction of microorganisms, improving the efficiency of the biological treatment and achieving efficient removal of nitrogen, phosphorus, and organic matter from the wastewater. This improves treatment efficiency, and offers advantages such as ease of operation, good operational stability, and low operating costs.

[0039] Multiple horizontal flow spaces are separated in the anaerobic and aerobic treatment units by diaphragms. Flat gates and flow equalization devices are used at the front end to regulate and equalize the sewage load, ensuring uniform distribution of water entering the horizontal flow spaces. This reduces turbulence or eddies and avoids excessively high or low localized flow rates, thereby improving the treatment efficiency and operational smoothness of the anaerobic and aerobic treatment units. The shape of the diaphragms creates independent treatment units with outward-expanding lumen structures, which not only enhances the turbulent effect of the fluid but also facilitates the uniform distribution of the biofill. Furthermore, the staggered distribution of the independent treatment units increases the density of the biofill, providing an adequate and ideal habitat for the growth and reproduction of microorganisms, promoting their growth and reproduction and thus improving biological treatment efficiency. The detachable structure of the diaphragms facilitates maintenance and inspection. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 Schematic diagram of the overall structure of the biological treatment unit.

[0042] Figure 3 Schematic diagram of the overall structure of the optimized biological treatment unit.

[0043] Figure 4Schematic diagram of the structure of the aerobic treatment unit.

[0044] Figure 5 Schematic diagram of the structure of the advection space.

[0045] Figure 6 Schematic diagram of the structure of the biological filler, A is the overall structure diagram, B is the structure diagram of the ring piece.

[0046] In the figure, 1 is the main water inlet, 2 is the pretreatment unit, 3 is the biological treatment unit, 4 is the post-treatment unit, 5 is the screen pool, 501 is the coarse screen, 502 is the fine screen, 6 is the grit chamber, 7 is the aerobic treatment tank, 701 is the first water 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 water 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, 102 is the second ultrasonic sensor, 10 3 is an aerobic sludge return pump, 104 is the second microporous aerator, 11 is a sand filter, 12 is a chemical reaction tank, 13 is an activated carbon adsorption tank, 14 is a deep oxidation tank, 15 is a total water outlet, 16 is a water quality detector, 17 is a water inlet seat, 18 is a volume buffer chamber, 19 is a flow equalizing device, 191 is a partition, 192 is a through hole, 20 is a processing unit cabinet, 21 is a horizontal flow space, 22 is a transverse partition, 211 is a diversion pipeline, 212 is an independent processing unit, 23 is a fixed partition, 24 is a biological filler, 241 is a center rope, 242 is a ring sheet, 243 is a fiber filler, 25 is a hydraulic cavitation device, 26 is a sludge treatment system, and 27 is a water outlet seat. DETAILED DESCRIPTION

[0047] The technical solutions of the present invention are further explained 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 shall be determined by the claims. Any modifications or substitutions made to the technical solutions of the present invention by those skilled in the art without creative effort shall fall within the scope of protection of the present invention.

[0048] Example 1 like Figure 1-6As shown, a eutrophic sewage treatment system, the total water inlet 1 is connected to the pretreatment unit 2, the biological treatment unit 3 and the post-treatment unit 4 in sequence, and the post-treatment unit 4 is connected to the total water outlet 15; the eutrophic sewage enters the system from the total water inlet 1, undergoes physical filtration in the pretreatment unit 2, removes impurities, large particles with a particle size greater than 0.5 mm and suspended matter in the sewage, and then enters the biological treatment unit 3 for aerobic treatment and anaerobic treatment; after the treatment is completed, it enters the post-treatment unit 4, and further removes residual pollutants in the water by physical adsorption, chemical oxidation and the like, thereby improving the effluent water quality. Finally, the treated water flows out through the total water outlet 16, completing the treatment of the eutrophic sewage; the biological treatment unit 3 It includes a front-end unit architecture and a back-end unit architecture; the front-end unit architecture is an aerobic treatment tank 7 and an anaerobic treatment tank 8 connected in parallel, which respectively perform aerobic treatment and anaerobic treatment on the sewage, and perform a pre-treatment on the sewage entering the biological treatment unit 3 at the front end, thereby improving the treatment efficiency and the system's adaptability to complex water quality, and can flexibly adjust the treatment load according to the actual water quality conditions to ensure efficient removal of pollutants; the back-end unit architecture is composed of an anaerobic treatment unit 9 and an aerobic treatment unit 10 connected in series, which perform anaerobically and aerobic treatment on the sewage in turn, further strengthen the treatment of the sewage, improve the treatment effect, and convert organic pollutants in the sewage into simple molecular harmless substances, such as carbon dioxide, water or methane.

[0049] Preferably, the anaerobic treatment unit 9 and the aerobic treatment unit 10 are both closed cabinet structures, including a treatment unit cabinet 20, with a water inlet seat 17 on one side of the treatment unit cabinet 20 and a water outlet seat 27 on the other side for the entry and exit of sewage; a volume buffer chamber 18 and a flat gate are sequentially provided on one side of the treatment unit cabinet 20 close to the water inlet seat 17, and a plurality of horizontal flow spaces 21 are provided on the other side of the flat gate, and the horizontal flow space 21 is connected to the water outlet seat 27 through the water outlet buffer chamber; the volume buffer chamber 18 is used to buffer the sewage entering the treatment unit cabinet 20 and reduce the impact force, and then the sewage entering the treatment unit cabinet 20 enters the horizontal flow space 21 for treatment after the load is adjusted by the flat gate, and the treated sewage enters the water outlet buffer chamber for collection, and then is discharged through the water outlet seat 27 to enter the next treatment process.

[0050] Further preferably, a flow balancing device 19 is provided in the flat gate; the flow balancing device 19 is composed of a plurality of staggered partitions 191; a plurality of through holes 192 are provided on the partitions 191. The sewage after the load is adjusted by the flat gate passes through the flow balancing device 19 to optimize the flow characteristics, so that the sewage flow entering each horizontal flow space 21 is evenly distributed, the flow deviation is ≤10%, and the total flow fluctuation range is ±5%, thereby reducing the generation of turbulence or eddy currents, avoiding excessively high or low local flow velocities, and thereby improving the overall treatment efficiency of the corresponding aerobic treatment unit 10 or anaerobic treatment unit 9.

[0051] More preferably, the through holes 192 are distributed in a plum blossom shape, the diameter of the through holes is 15-25 mm, and the hole spacing is 60-100 mm.

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

[0053] Further preferably, the horizontal flow space 21 is separated by a transverse partition 22, and the transverse partition 22 is fixed and limited by a fixed partition frame 25; the transverse partition 22 is placed on the fixed partition frame 25, dividing the space after the flow equalizing device 19 into multiple horizontal flow spaces 21, and independently treating the water body.

[0054] Further preferably, the fixed partition 25 is evenly fixed on the side wall of the flow equalizing device 19 and the water outlet buffer chamber close to the horizontal flow space 21 to form a fixed component for fixing and limiting the position of the diaphragm 22. At the same time, the diaphragm 22 is placed on the fixed partition 25 and can be pulled out for cleaning and maintenance, while also exposing the corresponding horizontal flow space 21 for maintenance; a fixing part is provided at the bottom of each fixed partition 25 for fixing the center rope 241 in the biological filler 24.

[0055] More preferably, the transverse partition 22 is directly formed and corresponds to the structure of the guide pipe 211 and the independent processing unit 212, so that two adjacent transverse partitions 22 can be combined to obtain an independent processing unit 212 with an external expanded hole cavity structure and a horizontal flow space 21 connected in sequence to the guide pipe 211.

[0056] Furthermore, Φ10mm ventilation holes are provided on the top of the transverse partition, which are distributed in a plum blossom shape with a spacing of 150mm, and are matched with gas guide grooves (depth 20mm, width 30mm) to ensure aeration uniformity.

[0057] More preferably, the horizontal flow space 21 is provided with a diversion pipeline 211 and an independent treatment unit 212 connected in sequence; the diversion pipeline 211 and the independent treatment unit 212 are provided with biological fillers 24, which can independently treat the water body.

[0058] Further preferably, the independent processing unit 212 is a fast-expanding tubular structure, the diameter at the widest point is 1.5-2.5 times the diameter at the narrowest point, and the diameter at the narrowest point is equal to the diameter of the diversion pipeline; the biological filler 24 includes a central rope 241 and a fiber filler 243; the fiber filler 243 is fixed on the ring piece 242 and then fixed on the central rope 241.

[0059] Furthermore, the rapid expansion lumen structure is specifically olive-shaped, spindle-shaped or straight-tube-shaped, with a large middle and small ends.

[0060] Furthermore, in each horizontal flow space 21, the independent treatment units 212 are staggered, which increases the arrangement density of the biological filler 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 filler, thereby improving the biological treatment efficiency.

[0061] Preferably, a first flat gate 901 is provided inside the anaerobic treatment unit 9, and an anaerobic sludge return pump 903 and a first ultrasonic sensor 902 are provided 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 is started and 50%-100% of the sludge in the anaerobic treatment unit 9 is returned to the anaerobic treatment tank 8. The remaining sludge that is not returned enters the sludge treatment system 26 for concentration, digestion and dehydration treatment.

[0062] Further preferably, the set threshold value of the sludge thickness is 3-8 mm.

[0063] Preferably, a second flat gate 101 and a second microporous aerator 104 are provided inside the aerobic treatment unit 10, and a second ultrasonic sensor 102 and an aerobic sludge return pump 103 are provided 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, and the remaining sludge that is not returned enters the sludge treatment system 26 for concentration, digestion and dehydration.

[0064] Further preferably, the set threshold value of the sludge thickness is 3-8 mm.

[0065] Further 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 50 mm. An adjustable weir gate is installed in the trough with an adjustment range of 20-50 mm to facilitate sludge sedimentation and backflow.

[0066] Further preferably, the first flat gate 901 and the second flat gate 101 are rising flat gates or descending flat gates, which are any one of screw drive, hydraulic drive and electric drive; they can control the height adjustment of the gate according to the sewage load, and thus adjust the number of activated advection spaces 21, wherein when the sewage load is COD 300-500mg / L, 100% of the advection space is activated; when the sewage load is COD 150-300mg / L, 50%-60% of the advection space is activated; when the sewage load is COD<150mg / L, 20-30% of the advection 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 to reduce aeration energy consumption. At the same time, the microbubbles will drive the water flow during their rise, enhance water disturbance, promote full contact between microorganisms and pollutants, and further improve the biological treatment efficiency. In addition, the hydraulic cavitation effect can also produce a local high-temperature and high-pressure environment, which is conducive to the decomposition of difficult-to-degrade organic matter and prevent pipeline blockage, so that it exhibits stronger adaptability and efficiency when treating complex eutrophic water bodies.

[0068] Further preferably, the hydrodynamic cavitation device 25 is a venturi tube or a perforated plate HC reactor.

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

[0070] Further preferably, the dissolved oxygen detector is any one of the LianCe_SIN-DM2800 DO meter, the fluorescence dissolved oxygen tester MIK-DY2900, and the SZ-RJYB online dissolved oxygen meter / DO meter; the microporous aerator is any one of a suspended chain aerator, a diaphragm microporous aerator, a tubular aerator, and the like.

[0071] Preferably, the pretreatment unit 2 includes a grid pool 5 and a grit chamber 6 connected in series, which perform pre-filtration treatment on the eutrophic sewage to remove debris, large particles with a particle size greater than 0.5 mm and suspended matter to avoid clogging subsequent treatment units and connecting pipes; the post-treatment 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, which perform secondary filtration and deep oxidation on the sewage to improve water quality.

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

[0073] Further preferably, the grit chamber 6 is a horizontal flow grit chamber; the water outlet of the grit chamber 6 is provided with a filter cloth screen with a pore size of 0.2-0.5 mm, which removes heavier inorganic particles through gravity sedimentation and reduces the burden on subsequent treatment units; the filter cloth screen serves as the last physical filtration barrier to further refine the filtration effect and ensure that the water quality of the outlet water of the pretreatment unit meets the requirements of the subsequent biological treatment unit.

[0074] Further preferably, the sand filter 11 is a pressure-type sand filter. When the pressure differential is greater than 0.15 MPa, water flows in from the bottom and out from the top. When the pressure differential is ≤ 0.15 MPa, water flows in from the bottom and out from the top. When raw water enters the sand filter through the inlet pipe, it first enters the support layer, where larger particles are initially intercepted. The water then flows through the quartz sand layer, where the pores and gaps between the quartz sand particles intercept and adsorb suspended matter, 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 matter, achieving deep filtration.

[0075] Further preferably, the structure of the chemical reaction tank 12 is substantially the same as that of a chemical dosing tank or a chemical dosing system commonly used in sewage treatment, and is provided with a stirring device. Chemical agents such as coagulants and coagulant aids are added from the top of the chemical reaction tank 12, and the condensed and precipitated substances are regularly 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, flocculants such as PAC and PAM are added to react with water to form flocculated precipitates, which absorb suspended impurities in the water, and then coagulant aids are used to assist the flocculation and precipitation to achieve solid-liquid separation; at the same time, a stirring device is used to help the added flocculants mix quickly and evenly with the water to fully flocculate the suspended impurities.

[0076] Further preferably, the water in the activated carbon adsorption tank 13 is inlet and outlet from the bottom, and the strong physical adsorption capacity of the activated carbon is used to effectively adsorb organic pollutants in the wastewater. In addition, during the activation process, some oxygen-containing functional groups such as carboxyl (-COOH), hydroxyl (-OH), and carbonyl are formed on the non-crystalline part of the activated carbon surface, so that the activated carbon has certain chemical adsorption and catalytic oxidation and reduction properties, which can effectively remove some metal ions in the wastewater and remove suspended impurities that are not completely flocculated in the reagent reaction tank 12; the deep oxidation tank 14 includes a dosing device and a stirring device , by adding strong oxidants such as chlorides to deeply purify the water quality; photochemical oxidation method (adding semiconductor catalysts through a dosing device, mixing evenly and then assisting with ultraviolet light irradiation), catalytic wet oxidation method (adding catalysts through a dosing device and a stirring device, mixing evenly, and cooperating with a heating and pressurizing device to maintain a high temperature and high pressure environment to oxidize and decompose the sewage), Fenton oxidation method (using a dosing device to add iron salts and hydrogen peroxide, stirring a device to mix evenly and then oxidize and degrade pollutants) or Fenton-like methods can also be used to deeply oxidize the water body and purify the water quality.

[0077] Preferably, a water quality detector 16, a water inlet regulating valve and a water pressure regulating pump are provided on the pipeline connecting the pretreatment unit 2 and the biological treatment unit 3 to perform water quality detection on the sewage treated by the pretreatment unit 2 and to regulate the water volume and water pressure entering the biological treatment unit 3.

[0078] Further preferably, the water quality detector 16 is used to detect the water quality of the sewage after being treated by the pretreatment unit 2, and then the water inlet regulating valve and the water pressure regulating pump are controlled by the control unit connected through the communication according to the water quality data to control the amount and pressure of water entering the biological treatment unit 3.

[0079] Further 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; the pipeline connecting the grit chamber 6 and the aerobic treatment tank 7 is provided with a water quality detector 16, a first water inlet regulating valve 701 and a first water pressure regulating pump 702; the pipeline connecting the grit chamber 6 and the anaerobic treatment tank 8 is provided with a water quality detector 16, a second water inlet regulating valve 801 and a second water pressure regulating pump 802.

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

[0081] Preferably, a real-time water quality feedback system is provided on the outlet pipelines of the pretreatment unit 2, the biological treatment unit 3 and the post-treatment unit 4; the real-time water quality feedback system includes an online sensor group, which is communicatively connected to the control unit to implement feedback of water quality data, and controls the aeration intensity of the microporous aerator connected in communication through an algorithm preset in the control unit, and controls the height of the flat gate, thereby controlling the number of activated horizontal flow spaces 21; the sensor group includes a combination of a pH sensor, a dissolved oxygen sensor, an ammonia nitrogen sensor, and a total phosphorus sensor.

[0082] Example 2 A eutrophic sewage treatment system as described in Example 1 was constructed to treat sewage. The sewage was sourced from a eutrophic river in an urban-rural fringe area in Hunan Province. The sewage 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 algae density of 1.5 × 10 6 -2.5×10 6 cells / mL, water transparency is 0.3-0.5m; (1) The eutrophic wastewater enters the treatment system through the main water inlet 1 and is physically filtered through the pretreatment unit 2; (2) After physical filtration, the water volume and pressure are detected and adjusted by the water quality detector 16, the water inlet regulating valve and the water pressure regulating pump, and then enter the biological treatment unit, enter the aerobic treatment tank 7, the anaerobic treatment tank 8, and then pass through the anaerobic treatment unit 9 and the aerobic treatment unit 10 in sequence; the water volume entering the aerobic treatment tank 7 is 15m 3 , the water pressure is 0.4 bar, and the amount of water entering the anaerobic treatment tank 8 is 15m 3, the 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, wherein PAC 50 mg / L + PAM 0.5 mg / L is added to the reagent reaction tank 12 in the post-treatment unit 4, and sodium hypochlorite is added to the deep oxidation tank 14 to deeply oxidize the wastewater and remove pollutants.

[0083] After 30 days of treating a eutrophic river using this method, the ammonia nitrogen content in the water dropped to 1.5 mg / L, the total phosphorus content to 0.4 mg / L, and the COD content to 30 mg / L. Algae density decreased by 80%, and water transparency increased to 1.2 meters. Treated eutrophic wastewater can be discharged directly into the river, used for agricultural irrigation, or sent to a domestic sewage treatment plant for further purification. This purification process effectively reduces the operating burden of related equipment, improving operational stability and reliability, and extending its service life.

Claims

1. A eutrophic wastewater treatment system, characterized by: The total water inlet (1) is connected to the pretreatment unit (2), the biological treatment unit (3) and the post-treatment unit (4) in sequence, and the post-treatment unit (4) is connected to the total water outlet (15); the biological treatment unit (3) includes a front-end unit structure and a back-end unit structure; the front-end unit structure is an aerobic treatment tank (7) and an anaerobic treatment tank (8) connected in parallel; the back-end unit structure is an anaerobic treatment unit (9) and an aerobic treatment unit (10) connected in series in sequence.

2. A eutrophic wastewater treatment system according to claim 1, characterized in that: The anaerobic treatment unit (9) and the aerobic treatment unit (10) are both cabinet structures, including a treatment unit cabinet (20), wherein one side of the treatment unit cabinet (20) is provided with a water inlet seat (17), and the other side is provided with a water outlet seat (27); a volume buffer chamber (18) and a flat plate gate are sequentially provided on one side of the treatment unit cabinet (20) close to the water inlet seat (17), and a plurality of advection spaces (21) are provided on the other side of the flat plate gate, and the advection spaces (21) are connected to the water outlet seat (27) via the water outlet buffer chamber.

3. A eutrophic wastewater treatment system according to claim 2, characterized in that: A flow balancing device (19) is provided in the flat gate; the flow balancing device (19) is composed of a plurality of staggered partitions (191); and a plurality of through holes (192) are provided on the partitions (191).

4. A eutrophic wastewater treatment system according to claim 2, characterized in that: The advection space (21) is separated by a transverse partition (22), and the transverse partition (22) is fixed and limited by a fixed partition frame (25).

5. A eutrophic wastewater treatment system according to claim 4, characterized in that: The advection space (21) is provided with a flow guiding pipeline (211) and an independent processing unit (212) connected in sequence; biological fillers (24) are provided in the flow guiding pipeline (211) and the independent processing unit (212).

6. A eutrophic wastewater treatment system according to claim 5, characterized in that: The independent processing unit (212) is a fast-expanding tubular structure, the diameter at the widest point is 1.5-2.5 times the diameter at the narrowest point, and the diameter at the narrowest point is equal to the diameter of the diversion pipeline; the biological filler (24) includes a central rope (241) and a fiber filler (243); the fiber filler (243) is fixed to the ring piece (242) and then fixed to the central rope (241).

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

8. The eutrophic wastewater treatment system according to claim 1, characterized in that: A water quality detector (16), a water inlet regulating valve and a water pressure regulating pump are provided on the pipeline connecting the pretreatment unit (2) and the biological treatment unit (3).

9. A method for using a eutrophic wastewater treatment system according to any one of claims 1 to 8, characterized in that: The steps include: (1) Eutrophic wastewater enters the treatment system through the main water inlet (1) and is physically filtered through the pretreatment unit (2); (2) After physical filtration, the water is tested and the water pressure is adjusted by a water quality detector (16), a water inlet regulating valve and a water pressure regulating pump, and then enters the biological treatment unit for aerobic treatment, anaerobic treatment, and then anaerobic treatment and aerobic treatment in sequence; (3) After the biological treatment is completed, it enters the post-treatment unit (4) for deep oxidation.

10. The method of use according to claim 9, wherein: When the sewage is subjected to anaerobic treatment and aerobic treatment in sequence, the activation level of the advection space (21) is adjusted by using a flat gate according to the sewage load, and the total flow fluctuation range is made within ±5% by using a flow equalizing device (19), and the flow deviation entering each advection space (21) is ≤10%; when the sewage load is COD 300-500 mg / L, 100% of the advection space is activated; when the sewage load is COD 150-300 mg / L, 50%-60% of the advection space is activated; when the sewage load is COD <150 mg / L, 20-30% of the advection space is activated.

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