A low-energy, long-lasting purification system for small and medium-sized polluted water bodies

Abstract

This utility model relates to a low-energy, long-lasting purification system for small to medium-sized polluted water bodies. It includes an anaerobic zone, an oxidation-aerobic zone, and an anoxic zone arranged sequentially along the water flow direction. A fully covered floating island area and a sponge iron deoxygenation zone are set up in the anaerobic and anoxic zones to create a low-oxygen environment. An oxygen-rich environment is created by installing an ozone generator and a wind-collecting aeration device. The water first flows through the anaerobic zone, where easily degradable organic matter undergoes preliminary biological transformation. It then enters the oxidation-aerobic zone to oxidize and decompose recalcitrant organic matter. Afterward, carrying dissolved oxygen, it sequentially enters the aerobic and anoxic zones to achieve efficient removal of pollutants. Later, the continuous oxygen supply from the ozone generator and wind-collecting aeration device, along with periodic heating by the deoxygenation device, maintains a suitable growth environment for microorganisms and plants, achieving a continuous purification effect.

Description

Technical Field

[0001] This utility model relates to the field of water treatment, and in particular to a low-energy-consumption, long-lasting purification system for small and medium-sized polluted water bodies. Background Technology

[0002] With the improvement of living standards and the increasing demands for environmental quality, the pollution problems of small and medium-sized water bodies in urban and rural areas have gradually attracted attention. These water bodies are greatly affected by pollutants from the surrounding environment, and their small water area, weak water cycle, and relatively simple aquatic ecosystem structure and function, coupled with poor self-regulation and resistance to external disturbances, have led to increasingly obvious water pollution, seriously affecting their environmental and landscape benefits.

[0003] Traditional physical and chemical methods can only temporarily alleviate the deterioration of water bodies and cannot effectively remove some recalcitrant organic matter. This approach is neither economical nor conducive to sustainable development, making the long-term management of small and medium-sized water bodies a challenging problem. Utility Model Content

[0004] The purpose of this invention is to propose a low-energy, long-lasting purification system for small and medium-sized polluted water bodies. By dividing the water body into zones and treating them step by step, the water body can be purified efficiently and continuously.

[0005] To achieve the above objectives, this utility model provides a low-energy-consumption, long-lasting purification system for small and medium-sized polluted water bodies, including an anaerobic zone set along the water flow direction and at least one set of oxidation-aerobic zone and anoxic zone.

[0006] The anaerobic zone includes a front end and an end deoxygenation zone, a first anaerobic bioreactor zone in the middle, and multiple sets of floating plant beds set on top. Aquatic plants are grown on the floating plant beds. The deoxygenation zone includes deoxygenation devices vertically spaced in the water. Each deoxygenation device includes multiple sets of vertically parallel perforated sponge iron plates and stainless steel plates, a DC power supply connected to the perforated sponge iron plates and stainless steel plates respectively via wires, and a control switch set on the wires. The perforated sponge iron plates and stainless steel plates are staggered at 45° to the direction of water flow. The first anaerobic bioreactor zone is a first immobilized microbial chamber suspended vertically on the floating plant beds. The first immobilized microbial chamber contains immobilized ammonifying bacterial balls.

[0007] The oxidation-aerobic zone includes an oxidation zone and an aerobic zone arranged sequentially along the water flow direction. The oxidation zone includes multiple air-collecting and aeration devices installed in the water, a second immobilized microbial chamber suspended between the air-collecting and aeration devices, submerged plants suspended on the air-collecting and aeration devices, and a nano-TiO2 coating on the outside of the air-collecting and aeration devices. The air-collecting and aeration devices include two funnel-shaped air inlets connected on their narrow sides on the water surface, a bidirectional switch that can move in both directions at the connection between the two air inlets, and a rotating shaft connecting the two air inlets. The system includes a narrow-sided vertically connected air supply pipe, an aeration disc installed underwater and connected to the bottom of the air supply pipe, a pressure-reducing sleeve installed around the air supply pipe, a Venturi fitting installed at the upper end of the pressure-reducing sleeve, and a fixing pile installed at the bottom for fixing the device. The diameter of the pressure-reducing sleeve is 1.5 times that of the air supply pipe, and the lower end has a trumpet-shaped opening. Multiple sets of pulleys are provided on the outside of the pressure-reducing sleeve. Planting boxes are suspended on the pulleys by ropes. The bottom of the planting boxes is filled with polyphosphate-fixed polyphosphate balls, and submerged plants are planted in the planting boxes.

[0008] The anoxic zone includes a front end and an end deoxygenation zone, a middle second anaerobic bioreactor zone, and multiple sets of floating plant beds set on top. Aquatic plants are planted on the floating plant beds. The deoxygenation zone includes deoxygenation devices that are vertically spaced in the water. The second anaerobic bioreactor zone is a third immobilized microbial chamber that is suspended on the floating plant beds and vertically set in multiple sets. The third immobilized microbial chamber contains immobilized denitrifying bacteria balls.

[0009] Preferably, the distance between the perforated sponge iron plate and the stainless steel plate is less than 10cm, the width of the plate is 30~50cm, and the height is 1~1.5m.

[0010] Preferably, when the dissolved oxygen content of the water is 0.5 mg / L or below, no deoxygenation zone is set at the front end; when the dissolved oxygen content of the water is 0.5~2 mg / L, the length of the deoxygenation zone set at the front end is 1~2 m; when the dissolved oxygen content of the water is 2~3 mg / L, the length of the deoxygenation zone set at the front end is 2~3 m; and the length of the deoxygenation zone set at the end is 1~1.5 m.

[0011] Preferably, the first immobilized microbial chamber has a side length of less than 15cm, the mesh size is smaller than the diameter of the prepared immobilized ammonified bacterial balls, and the spacing between each group is 30~50cm.

[0012] Preferably, the length of the first anaerobic biological reaction zone is determined based on the water flow velocity, and the hydraulic retention time is 1-2 hours, calculated using the formula: L A =V*T, where L AV is the length of the anaerobic biological reaction zone, in meters; V is the water flow velocity, in meters per hour; and T is the hydraulic retention time, in hours. For polluted water bodies with COD between 50 and 100 mg / L, T is 1 to 1.5 hours; for heavily polluted water bodies with COD greater than 100 mg / L, T is 1.5 to 2 hours.

[0013] Preferably, the air intake is located 3-5m above the water surface; the aeration disc has a diameter of 0.2-0.3m and is provided with holes with a diameter of 0.9-1.1cm, the outside of which is blocked by a hollow ball valve with a diameter of 1.2-1.5cm; the pulley is located 50-100cm above the water surface.

[0014] Preferably, the Venturi tube is flared at both ends, with a flared diameter of 0.4m and a width of 0.5m on one side. The flared Venturi tube is connected in the middle by a narrow tube with a length twice the diameter of the air supply pipe, and the narrow tube is connected to the pressure reducing sleeve.

[0015] Preferably, the second immobilized microbial chamber is a cubic mesh cage, and the second immobilized microbial chamber contains immobilized nitrifying bacteria balls; multiple second immobilized microbial chambers are connected in series by metal wires to form a chain and arranged in the direction of water flow, with both ends fixed to the air supply pipe, and the spacing between the second immobilized microbial chambers is 20~30cm.

[0016] Preferably, the top of the planting box is provided with a sliding cover, and the planting boxes are connected in a chain by stainless steel ropes and arranged perpendicular to the direction of water flow. The planting boxes forming the chain are arranged at intervals of 50-60cm from the bottom to the water surface. The side of the planting boxes forming the chain is provided with movable pulleys, and the movable pulleys are connected to each other by ropes.

[0017] Based on the above technical solution, the advantages of this utility model are:

[0018] This novel system is designed with zones according to the water flow direction. An anaerobic zone is created at the very beginning of the water body, followed by multiple oxidation, aerobic, and anoxic zones. This design removes not only conventional pollutants but also some recalcitrant organic matter from daily life. During operation, the system controls the temperature and oxygen content of the water through the deoxygenation device, ensuring the activity of the microorganisms. Therefore, this novel system not only achieves excellent treatment results during the treatment process but also enables long-term maintenance of the treated water. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of the low-energy-consumption, long-lasting purification system for small and medium-sized polluted water bodies according to this utility model;

[0021] Figure 2 This is a schematic diagram of the deoxygenation unit layout;

[0022] Figure 3 This is a schematic diagram of the deoxygenation device.

[0023] Figure 4 This is a schematic diagram of the perforated sponge iron plate structure;

[0024] Figure 5 This is a schematic diagram of the air collection and aeration device.

[0025] Figure 6 This is a schematic diagram of the planting box structure. Detailed Implementation

[0026] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] This invention provides a low-energy, long-lasting purification system for small to medium-sized polluted water bodies. The system is structured sequentially from front to back along the water flow direction: an anaerobic zone, an aerobic oxidation zone, and an anoxic zone. A fully covered floating island area and a sponge iron deoxygenation zone are incorporated into the anaerobic and anoxic zones to create a low-oxygen environment. An oxygen-rich environment is created by installing an ozone generator and a wind-collecting aeration device. The water first flows through the anaerobic zone, where readily biodegradable organic matter undergoes preliminary biological transformation. It then enters the aerobic oxidation zone to oxidize and decompose recalcitrant organic matter. Finally, carrying dissolved oxygen, the water sequentially flows into the aerobic and anoxic zones, achieving efficient removal of pollutants. The continuous oxygen supply from the ozone generator and wind-collecting aeration device, along with periodic heating from the deoxygenation device, maintains a suitable growth environment for microorganisms and plants, achieving continuous purification.

[0028] like Figure 1 As shown, the low-energy, long-lasting purification system includes an anaerobic zone A arranged along the water flow direction, and at least one set of oxidation-aerobic zones B and anoxic zones C. Anaerobic zone A is divided into three sections according to the water flow direction: deoxygenation zones at the front and end, and a first anaerobic biological reaction zone in the middle. The top is equipped with floating plant beds 2 to reduce the reoxygenation process.

[0029] Specifically, the anaerobic zone A includes a front end and an end deoxygenation zone, a first anaerobic biological reaction zone in the middle, and multiple sets of floating plant beds 2 set on top. Aquatic plants 4 are planted on the floating plant beds 2. The deoxygenation zone includes deoxygenation devices 1 that are vertically spaced in the water to remove dissolved oxygen.

[0030] like Figure 2 , Figure 3As shown, the deoxygenation device 1 includes multiple sets of vertically parallel perforated sponge iron plates 6 and stainless steel plates 7, a DC power supply 9 connected to the perforated sponge iron plates 6 and stainless steel plates 7 respectively via wires, and a control switch 8 mounted on the wires. Figure 2 As shown, the perforated sponge iron plate 6 and stainless steel plate 7 are staggered at 45° to the water flow direction, with a distance of no more than 10cm. The width of the plate is 30~50cm and the height is 1~1.5m. The staggered arrangement at 45° to the water flow direction increases the hydraulic residence time.

[0031] like Figure 2 As shown, the upper end of the perforated sponge iron plate 6 is connected to the cathode of a 15V DC power supply, and the upper end of the stainless steel plate 7 is connected to the anode. A control switch 8 is installed in the circuit. When the dissolved oxygen concentration exceeds 0.5mg / L after water flows through the sponge iron, the control switch 8 is turned on to remove the rust using electrochemical action. After the rust is removed, the switch is turned off to continue removing dissolved oxygen. The perforated sponge iron plate 6 has holes, such as... Figure 4 As shown.

[0032] The length of the front-end deoxygenation zone is determined based on the oxygen content of the water: Preferably, when the dissolved oxygen content is 0.5 mg / L or below, no front-end deoxygenation zone is required; when the dissolved oxygen content is 0.5~2 mg / L, the length of the front-end deoxygenation zone is 1~2 m; when the dissolved oxygen content is 2~3 mg / L, the length of the front-end deoxygenation zone is 2~3 m; and the length of the end-end deoxygenation zone is 1~1.5 m. The 1 m long deoxygenation zone at the end prevents oxygen from diffusing from the oxidation-aerobic zone B into the anaerobic zone A.

[0033] The first anaerobic bioreactor zone consists of multiple vertically arranged immobilized microbial chambers 10 suspended on the plant floating bed 2. Each immobilized microbial chamber 10 contains immobilized ammonifying bacterial balls. Specifically, the first anaerobic bioreactor zone is spaced 0.8–1.2 m from the deoxygenation zone. The first immobilized microbial chambers 10 are suspended by the top plant floating bed 2, and each chamber contains immobilized ammonifying bacteria to complete the ammonification process of organic nitrogen in the water. The side length of each first immobilized microbial chamber 10 does not exceed 15 cm, the mesh size should be smaller than the diameter of the prepared immobilized bacterial balls, and the spacing between each group is 30–50 cm.

[0034] Preferably, the length of the first anaerobic biological reaction zone is determined based on the water flow velocity, and the hydraulic retention time is preferably 1-2 hours, calculated using the formula: L A =V*T; where L AV is the length of the anaerobic biological reaction zone, in meters; V is the water flow velocity, in meters per hour; and T is the hydraulic retention time, in hours. For polluted water bodies with COD between 50 and 100 mg / L, T is 1 to 1.5 hours; for heavily polluted water bodies with COD greater than 100 mg / L, T is 1.5 to 2 hours.

[0035] By setting up deoxygenation devices and floating aquatic plant beds, the oxygen content and reoxygenation capacity of polluted water can be further reduced, allowing ammonifying bacteria to complete the ammonification process of organic matter. At the same time, the floating aquatic plant beds can further remove pollutants in addition to preventing the reoxygenation process of the water. Connecting perforated sponge iron and stainless steel plates to form an electrolysis circuit not only facilitates the removal of rust produced by deoxygenation of sponge iron, but also allows the water to be heated by the temperature generated during electrolysis, ensuring the life activities of aquatic plants and microorganisms in the low-temperature season.

[0036] Furthermore, the oxidation-aerobic zone B includes an oxidation zone and an aerobic zone arranged sequentially along the water flow direction. An oxidation zone of 1-2m is set at the front end of the aerobic zone, where ozone is generated using low-voltage electrolysis. A solar cell is used as the power source for the ozone generator. Nano-TiO2 is coated on the outside of the air-collecting aeration device to achieve photocatalytic-ozone oxidation combined degradation of recalcitrant organic matter in the water. Simultaneously, dissolved oxygen and degraded organic matter are supplied to the next aerobic zone.

[0037] The oxidation zone degrades recalcitrant organic matter while simultaneously providing dissolved oxygen for the subsequent aerobic zone, thus initially increasing the oxygen content in the aerobic zone. The aerobic zone further increases the oxygen content of the water through a designed air-collecting aeration device, and completes the nitrification of ammonia nitrogen from the anaerobic stage by suspending immobilized nitrifying bacteria in small chambers.

[0038] Specifically, the oxidation zone includes multiple air-collecting aeration devices 5 disposed in the water, a second immobilized microbial chamber 11 suspended between the air-collecting aeration devices 5, submerged plants 20 suspended on the air-collecting aeration devices 5, and a nano-TiO2 coating disposed on the outside of the air-collecting aeration devices 5.

[0039] like Figure 5As shown, the air collection and aeration device 5 includes two funnel-shaped air inlets 14 connected on the narrow side and set on the water surface, a bidirectional switch 15 that can move in both directions at the connection of the two air inlets 14, an air supply pipe 17 that is vertically connected to the narrow side of the two air inlets 14 through a rotating shaft 16, an aeration disc 22 set underwater and connected to the bottom of the air supply pipe 17, a pressure-reducing sleeve 25 set around the air supply pipe 17, a Venturi tube fitting 18 set at the upper end of the pressure-reducing sleeve 25, and a fixing pile 24 set at the bottom for fixing the device. The diameter of the pressure-reducing sleeve 25 is 1.5 times the diameter of the air supply pipe 17 and the lower end opening is funnel-shaped. Multiple sets of pulleys 19 are provided on the outside of the pressure-reducing sleeve 25. A planting box 21 is suspended on the pulleys 19 by ropes. The bottom of the planting box 21 is filled with polyphosphate-polysaccharide balls 28 fixed by polyvinyl alcohol. Submerged plants 20 are planted in the planting box 21.

[0040] Specifically, the aeration device 5 is made of PVC material, with its top 3-5m above the water surface. It has two flared air inlets 14 on either side, each with a diameter of 0.6-0.8m and a width of 0.8-1m. A bidirectional switch 15 is located in the center. The bidirectional switch 15 is in the form of a baffle plate; it closes on the opposite side when airflow is strong, allowing air to flow downwards through a 5-8cm diameter air supply pipe 17 connected to a rotating shaft 16 to the bottom. An aeration disc 22 is connected to the bottom. The aeration disc 22 has a diameter of 0.2-0.3m and perforations of approximately 1cm. The outside of the perforations is blocked with a hollow ball valve 23 with a diameter of 1.2-1.5cm to prevent external water from entering the device when the wind is weak. The air supply duct 17 is surrounded by a pressure-reducing sleeve 25. The diameter of the pressure-reducing sleeve 25 is 1.5 times that of the air supply duct 17. The lower end has a funnel-shaped opening, with a diameter approximately 1.5 times that of the aeration disc 23. The upper end is connected to a Venturi tube assembly 18. The Venturi tube assembly 18 is also funnel-shaped at both ends, with a diameter of 0.4m and a width of approximately 0.5m on each side. It is connected in the middle by a narrow tube twice the diameter of the air supply duct 17, which is connected to the pressure-reducing sleeve 25. When air passes through, the wind speed increases, creating a local negative pressure that draws water upward from the bottom, reducing the upward pressure of the water on the hollow ball valve 23, making it easier for the air from the air supply duct 17 to diffuse downward into the water. Multiple sets of pulleys 19 are installed 50-100cm above the water surface to suspend the planting boxes 21 for submerged plants 20.

[0041] The aerobic zone's air collection and aeration device utilizes air inlets and air delivery pipes to directly aerate downwards, reducing energy losses during conversion. The air inlet's height exceeds its diameter, and a rotating shaft at the bottom automatically adjusts its orientation to the incoming wind direction using wind resistance, achieving efficient wind energy collection without manual adjustment. Furthermore, when air passes through the Venturi tube connected above the casing, airflow is further accelerated, achieving localized pressure reduction and siphoning the water flow upwards within the casing, reducing localized water pressure on the aeration discs and facilitating aeration.

[0042] Preferably, the second immobilized microbial chamber 11 is a cubic mesh cage with dimensions of approximately 10cm x 10cm x 10cm. The chamber contains immobilized nitrifying bacteria balls (nitrite-oxidizing bacteria and nitrate-oxidizing bacteria) to further convert the ammonia nitrogen produced in the anaerobic stage into nitrate nitrogen. These balls are strung together in a chain shape with metal wires, arranged in the direction of water flow, and fixed at both ends to the air supply pipe 17 of the air collection and aeration device 5. The distance between every two chambers is 20-30cm.

[0043] like Figure 6 As shown, the submerged plant 20 is fixed in a plastic planting box 21. The planting box 21 is approximately 15cm x 10cm x 10cm in length, width, and height, with a sliding cover 26 on top for easy placement of the plant. Each planting box 21 contains 3-5 *Hydrilla verticillata* plants as submerged plants. Polyphosphate-accumulating bacteria are fixed in the box with polyvinyl alcohol (PVA) and then filled into the planting box 21 to bury the roots of the *Hydrilla verticillata*, providing some fixation. The planting boxes 21 are connected in a chain by stainless steel ropes, arranged perpendicular to the water flow direction, with one rope every 50-60cm from the bottom to the water surface. The connected planting boxes 21 are fitted with movable pulleys 27 at both ends, with pulley 19 serving as fixed pulleys. The ropes are wound around and suspended, facilitating the lifting of the plant chain out of the water for regular cleaning of the submerged plants and polyphosphate-accumulating bacteria.

[0044] A combination of fixed and movable pulleys is used to suspend the submerged plant planting boxes, reducing the pulling force required during lifting. Immobilized polyphosphate-accumulating bacteria are filled into the planting boxes, which not only anchors the submerged plants and provides sufficient phosphorus for plant growth, but also allows the oxygen released by the submerged plants' photosynthesis to further increase the oxygen content in the water surrounding the polyphosphate-accumulating bacteria, accelerating the absorption of phosphorus from the water by the polyphosphate-accumulating bacteria. Using a single PVA layer to immobilize polyphosphate-accumulating bacteria that require regular removal reduces the cost of using immobilized polyphosphate-accumulating bacteria.

[0045] Except for the bioreactor zone, the anoxic zone is structurally identical to the anaerobic zone. The microbial chambers in the bioreactor zone are filled with immobilized denitrifying bacteria to remove nitrogen. The length of the bioreactor zone is the same as the preceding aerobic zone.

[0046] Specifically, the anoxic zone C includes a front end and an end deoxygenation zone, a middle second anaerobic biological reaction zone, and multiple sets of plant floating beds 2 set on top. Aquatic plants 4 are planted on the plant floating beds 2. The deoxygenation zone includes deoxygenation devices 1 vertically spaced in the water. The second anaerobic biological reaction zone is a third immobilized microbial chamber 13 suspended on the plant floating beds 2 and vertically set in multiple sets. The third immobilized microbial chamber 13 contains immobilized denitrifying bacteria balls.

[0047] Immobilized denitrifying bacteria in the anoxic zone can convert nitrate nitrogen produced in the upstream aerobic zone into nitrogen gas through denitrification, thus removing nitrogen from the water.

[0048] Furthermore, the low-energy-consumption, long-lasting purification system for small and medium-sized polluted water bodies of this invention can be operated in the following manner:

[0049] Treatment period: Ammonifying and nitrifying bacteria are immobilized using PVA+SA+biochar as a carrier, and polyphosphate-accumulating bacteria are immobilized using PVA. The low-energy, long-lasting purification system is constructed during the summer. The lengths of the bioreactor zones in the oxidation-aerobic zone B and the anoxic zone C are determined based on the length of the first anaerobic bioreactor zone. The ratio of the lengths of the first anaerobic bioreactor zone, the aerobic zone in the first group of oxidation-aerobic zones B (set along the water flow direction), and the second anaerobic bioreactor zone in the first group of anoxic zones C (set along the water flow direction) is 1:1.8:1.8. If the treatment section is long, a second group of oxidation-aerobic zones B and anoxic zones C is added, wherein the lengths of the aerobic zones in the second group of oxidation-aerobic zones B and anoxic zones C, and the second anaerobic bioreactor zone, are 1.2 to 1.5 times that of the first group.

[0050] After operation, monitor the dissolved oxygen in the deoxygenation zone of anaerobic zone A. When the dissolved oxygen content in the anaerobic zone is higher than 0.5 mg / L, close control switch 8 for 20-40 minutes to remove surface rust. Record the time interval from the start of system operation to the closing of control switch 8 and set the time for the next closure of control switch 8 accordingly. Similarly, control the dissolved oxygen in anoxic zone C to below 1 mg / L. When the dissolved oxygen is higher than 1 mg / L, close control switch 8 to remove rust. Record the time interval from the start of system operation to the closing of control switch 8 and set control switch 8 accordingly. The closing time; replace the submerged plants 20 and polyphosphate-accumulating bacteria balls 28 in the planting box 21 every 15-30 days; maintenance period: after the water quality meets the standards, remove all polyphosphate-accumulating bacteria balls 28 in the planting box 21, replace the submerged plants 20 and cover the roots of the submerged plants 20 with vermiculite, and put them back underwater. After that, extend the time for cleaning the black algae according to the growth of the submerged plants 20, or clean them seasonally, 2-3 times a year; in winter, increase the closing frequency and closing time of the timer switch 8 in each deoxygenation zone to increase the water temperature and ensure the life activities of plants and microorganisms in the water.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.

Claims

1. A low-energy, long-lasting purification system for small to medium-sized polluted water bodies, characterized in that: It includes an anaerobic zone (A) set along the direction of water flow, and at least one set of oxidation-aerobic zone (B) and anoxic zone (C); The anaerobic zone (A) includes a front end and an end deoxygenation zone, a first anaerobic bioreactor zone in the middle, and multiple sets of plant floating beds (2) set on top. Aquatic plants (4) are planted on the plant floating beds (2). The deoxygenation zone includes deoxygenation devices (1) set vertically at intervals in the water. The deoxygenation device (1) includes multiple sets of vertically parallel sponge iron perforated plates (6) and stainless steel plates (7), a DC power supply (9) connected to the sponge iron perforated plates (6) and stainless steel plates (7) respectively by wires, and a control switch (8) set on the wires. The sponge iron perforated plates (6) and stainless steel plates (7) are set at a 45° angle to the direction of water flow. The first anaerobic bioreactor zone is a first immobilized microbial chamber (10) set vertically in multiple sets suspended on the plant floating bed (2). The first immobilized microbial chamber (10) is filled with immobilized ammonified bacterial balls. The oxidation-aerobic zone (B) includes an oxidation zone and an aerobic zone arranged sequentially along the water flow direction. The oxidation zone includes multiple air-collecting aeration devices (5) arranged in the water, a second immobilized microbial chamber (11) suspended between the air-collecting aeration devices (5), submerged plants (20) suspended on the air-collecting aeration devices (5), and a nano-TiO2 coating arranged on the outside of the air-collecting aeration devices (5). The air-collecting aeration device (5) includes two funnel-shaped air inlets (14) connected on the narrow side on the water surface, a bidirectional switch (15) that can move in both directions at the connection of the two air inlets (14), and an air supply pipe (17) that is vertically connected to the narrow side of the two air inlets (14) through a rotating shaft (16). The device includes an aeration disc (22) installed underwater and connected to the bottom of the air supply pipe (17), a pressure-reducing sleeve (25) installed around the air supply pipe (17), a Venturi fitting (18) installed at the upper end of the pressure-reducing sleeve (25), and a fixing pile (24) installed at the bottom for fixing the device. The diameter of the pressure-reducing sleeve (25) is 1.5 times the diameter of the air supply pipe (17) and the lower end opening is a trumpet-shaped opening. Multiple sets of pulleys (19) are provided on the outside of the pressure-reducing sleeve (25). A planting box (21) is suspended on the pulleys (19) by ropes. The bottom of the planting box (21) is filled with polyphosphate-fixed polyphosphate balls (28) and submerged plants (20) are planted in the planting box (21). The anoxic zone (C) includes a front end, an end deoxygenation zone, a middle second anaerobic bioreactor zone, and multiple sets of plant floating beds (2) set on top. Aquatic plants (4) are planted on the plant floating beds (2). The deoxygenation zone includes deoxygenation devices (1) set vertically at intervals in the water. The second anaerobic bioreactor zone is a third immobilized microbial chamber (13) set vertically in multiple sets suspended on the plant floating beds (2). The third immobilized microbial chamber (13) contains immobilized denitrifying bacteria balls.

2. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The distance between the perforated sponge iron plate (6) and the stainless steel plate (7) is less than 10cm, the width of the plate is 30~50cm, and the height is 1~1.5m.

3. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: No deoxygenation zone is set up at the front end when the dissolved oxygen content of the water is 0.5 mg / L or below; when the dissolved oxygen content of the water is 0.5~2 mg / L, the length of the deoxygenation zone set at the front end is 1~2 m; when the dissolved oxygen content of the water is 2~3 mg / L, the length of the deoxygenation zone set at the front end is 2~3 m; and the length of the deoxygenation zone set at the end is 1~1.5 m.

4. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The first immobilized microbial chamber (10) has a side length of less than 15cm, and the mesh size is smaller than the diameter of the prepared immobilized ammonified bacterial balls. The spacing between each group is 30~50cm.

5. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The length of the first anaerobic biological reaction zone is determined based on the water flow velocity, and the hydraulic retention time is 1-2 hours. The calculation formula is: L A =V*T, where L A V is the length of the anaerobic biological reaction zone, in meters; V is the water flow velocity, in meters per hour; and T is the hydraulic retention time, in hours. For polluted water bodies with COD between 50 and 100 mg / L, T is 1 to 1.5 hours; for heavily polluted water bodies with COD greater than 100 mg / L, T is 1.5 to 2 hours.

6. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The air intake (14) is located 3-5m above the water surface; the aeration disc (22) has a diameter of 0.2-0.3m and is provided with holes with a diameter of 0.9-1.1cm. The outside of the holes is blocked by hollow ball valves (23) with a diameter of 1.2-1.5cm; the pulley (19) is located 50-100cm above the water surface.

7. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The Venturi fitting (18) is flared at both ends with a diameter of 0.4m and a width of 0.5m on one side. The flared Venturi fitting (18) is connected in the middle by a narrow pipe with a length twice the diameter of the air supply pipe (17). The narrow pipe is connected to the pressure reducing sleeve (25).

8. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The second immobilized microbial chamber (11) is a cubic mesh box, and the second immobilized microbial chamber (11) contains immobilized nitrifying bacteria balls; multiple second immobilized microbial chambers (11) are connected in series by metal wires to form a chain and arranged in the direction of water flow, with both ends fixed on the air supply pipe (17), and the spacing between the second immobilized microbial chambers (11) is 20~30cm.

9. The low-energy-consumption, long-lasting purification system according to claim 1, characterized in that: The top of the planting box (21) is provided with a sliding cover (26). The planting boxes (21) are connected in a chain by stainless steel rope and arranged perpendicular to the direction of water flow. The planting boxes (21) forming the chain are arranged every 50~60cm from the bottom to the water surface. The side of the planting boxes (21) forming the chain is provided with a movable pulley (27). The movable pulley (27) and the pulley (19) are connected by rope winding.

Images