Boron-magnesium reinforced plant oxygen excretion to achieve sulfur autotrophic denitrification and phosphorus removal and hydrogen sulfide reduction artificial wetland system and operation method

Abstract

The present application belongs to the technical field of sewage treatment, and particularly relates to a boron-magnesium reinforced plant oxygen excretion to realize sulfur autotrophic denitrification and phosphorus removal and hydrogen sulfide reduction amount of constructed wetland system and operation method. The system comprises a wetland system main body, the main body comprises a buffer zone and a reaction zone, and the two are separated by a porous plate; the buffer zone is provided with a water inlet; the reaction zone is provided with sulfur filter material capable of releasing boron and magnesium, the top end of the reaction zone is planted with wetland plants, and a water outlet is arranged; a hollow pipe is arranged in the center of the reaction zone, and a pH and dissolved oxygen probe is arranged in the pipe, the probe is connected with a pH and dissolved oxygen combined monitor through a wire; and the wetland system main body is connected with a water inlet bucket and a water outlet bucket. The system can realize low-carbon deep denitrification treatment of low-carbon nitrogen ratio sewage, realizes zero addition of external carbon source, the sulfur filter material capable of releasing boron and magnesium releases boron and magnesium elements to strengthen plant root oxygen excretion, an aerobic micro area appears, hydrogen sulfide is oxidized, hydrogen sulfide yield is reduced, and the generated elemental sulfur or sulfate further promotes sulfur autotrophic denitrification.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a boron-magnesium enhanced plant oxygen secretion system for sulfur autotrophic denitrification, phosphorus removal, and hydrogen sulfide reduction, and its operation method. Background Technology

[0002] Nitrogen and phosphorus pollutants generated by human activities are a major cause of eutrophication in water bodies. Excessive emissions of nitrogen and phosphorus can lead to the deterioration of the aquatic environment. Minimizing the amount of nitrogen and phosphorus pollutants entering natural water bodies is an important way to control eutrophication and ensure water use and ecological security.

[0003] Traditional heterotrophic denitrification is a key step in nitrogen removal from water bodies and has been widely used in wastewater treatment. However, it usually requires additional carbon sources, resulting in high operating costs and difficulty in precisely controlling the dosage. This can easily lead to excessive COD in the effluent or incomplete denitrification, while also releasing greenhouse gases and exacerbating global warming. Phosphorus removal relying on polyphosphate-accumulating bacteria under anaerobic-aerobic conditions is a widely adopted method. However, because polyphosphate-accumulating bacteria and related denitrifying bacteria have different sludge ages, there is a contradiction in achieving simultaneous nitrogen and phosphorus removal.

[0004] Sulfur autotrophic denitrification technology uses reduced sulfur as an electron donor to reduce nitrate nitrogen to nitrogen gas in an anaerobic environment. Compared with traditional heterotrophic denitrification, it has advantages such as no need to add organic carbon sources, wide availability and low cost of sulfur sources, good adaptability to fluctuations in influent nitrogen load, and low sludge production, making it a new approach for low-carbon, deep nitrogen removal in constructed wetlands. However, the sulfur autotrophic denitrification process produces sulfate, causing the pH to drop to acidic levels. Furthermore, due to the anaerobic and anoxic environment in the wetland substrate, sulfate is converted to hydrogen sulfide by sulfate-reducing bacteria. This is the main reason for root rot and black, odorous water formation after the application of constructed wetlands. Hydrogen sulfide is also an acutely toxic gas, harmful to human health. In addition, a single sulfur autotrophic denitrification process cannot achieve simultaneous phosphorus removal; it needs to be coupled with other processes to achieve deep phosphorus removal. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a boron-magnesium enhanced plant oxygen secretion system and its operation method for achieving sulfur autotrophic denitrification, phosphorus removal, and hydrogen sulfide reduction. The system constructs a vertical subsurface flow type constructed wetland system, in which boron-magnesium-releasing sulfur filter media and quartz sand are added to the reaction zone. Boron and magnesium elements are released in the upper part of the reaction zone, enhancing oxygen secretion from plant roots, regulating the environment around the wetland roots, and reducing hydrogen sulfide production. Simultaneously, the iron salts precipitated from the boron-magnesium-releasing sulfur filter media achieve deep removal of phosphorus-containing pollutants, realizing a sulfur autotrophic denitrification-constructed wetland coupled system. This achieves the goal of low-carbon, deep denitrification and phosphorus removal from nitrogen- and phosphorus-containing wastewater, with the effluent meeting the Class IV water quality requirements of the Chinese Surface Water Environmental Standard.

[0006] The technical solution adopted is as follows:

[0007] A boron-magnesium enhanced plant oxygen secretion constructed wetland system to achieve sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction includes a vertical flow wetland system body, which includes a bottom buffer zone and an upper reaction zone, separated by a perforated plate.

[0008] The buffer zone is equipped with a base, and an inlet is provided on the side of the upper area of ​​the base. The upper layer of the buffer zone is a perforated plate. The upper layer of the perforated plate is a reaction zone, in which sulfur filter media and quartz sand that can release boron and magnesium are added. The top of the reaction zone is open for planting wetland plants. An outlet is provided on the side wall of the reaction zone near the top opening.

[0009] A hollow tube is set in the center of the reaction zone, and a pH and dissolved oxygen probe is placed inside the hollow tube. The pH and dissolved oxygen probe is connected to a pH and dissolved oxygen combined monitoring instrument via wires.

[0010] The inlet of the main body of the wetland system is connected to the inlet tank via a peristaltic pump, and its outlet is connected to the outlet tank.

[0011] Preferably, the reaction zone is cylindrical, and a row of filter media sampling ports is evenly arranged on its sidewall from bottom to top, with at least two filter media sampling ports.

[0012] As a further preferred embodiment, a water sampling port is uniformly arranged from bottom to top on the sidewall of the reaction zone, and at least two water sampling ports are provided.

[0013] As a further preferred embodiment, the buffer zone, except for the base portion, is cylindrical, the cylindrical diameter of the reaction zone is equal to the cylindrical diameter of the buffer zone, and the height ratio of the buffer zone to the reaction zone is 1:3 to 20.

[0014] An air inlet is provided on the opposite side of the water inlet of the buffer zone, and the air inlet is connected to an aeration pump.

[0015] Preferably, the porous plate is a circular plate with a certain thickness, with two circumferences. The diameter of the inner circumference is adapted to the diameter of the buffer zone and the reaction zone. Several water distribution holes are evenly arranged in the inner circle for supporting the filter media and distributing water evenly.

[0016] The diameter of the outer circumference of the porous plate is larger than the diameter of the reaction zone, and the connection between the porous plate and the buffer zone and the reaction zone is a closed connection.

[0017] The diameter of the water distribution holes is smaller than the diameter of the sulfur filter media particles that can release boron and magnesium.

[0018] Preferably, the roots of the wetland plants are located at the water outlet.

[0019] Preferably, the boron-magnesium-releasing sulfur filter media is uniformly mixed with quartz sand in a ratio of 3 to 5:1. The boron-magnesium-releasing sulfur filter media is prepared using waste materials containing sulfur, iron, boron, and magnesium generated in industrial production. In the upper part of the reaction zone, when the pH is in the range of 5.75-6.85, the release of boron and magnesium elements can be promoted.

[0020] Preferably, the top of the hollow tube is higher than the top of the reaction zone, and the hollow tube is a PVC tube with a number of evenly distributed small holes.

[0021] The operation method of a boron-magnesium enhanced plant oxygen secretion constructed wetland system to achieve sulfur autotrophy, nitrogen and phosphorus removal, and hydrogen sulfide reduction includes the following steps:

[0022] (1) Connect the water inlet tank, peristaltic pump, and wetland system body through the water inlet pipe, and connect the water inlet pipe to the water inlet of the buffer zone; connect the wetland system body and water outlet tank through the water outlet pipe, and connect the water outlet pipe from the water outlet of the reaction zone to the water outlet tank;

[0023] (2) Start the peristaltic pump. The sewage enters the buffer zone of the main body of the wetland system from the inlet tank through the inlet pipe. The water inlet is continuous flow. After passing through the perforated plate, it enters the reaction zone. In the reaction zone, nitrogen and phosphorus pollutants are removed from bottom to top through sulfur filter media that can release boron and magnesium. The pH and dissolved oxygen probes monitor the pH value and dissolved oxygen concentration in the hollow tube in real time. The water retention time is 2 to 4.5 hours.

[0024] (3) The purified wastewater flows from the outlet of the reaction zone through the outlet pipe into the outlet bucket and is discharged into the natural water body.

[0025] Preferably, in step (2), in the lower part of the reaction zone, some dissolved oxygen is introduced into the influent, causing nitrification, consuming dissolved oxygen, and converting ammonia nitrogen into nitrate; in the middle of the reaction zone, an autotrophic denitrification process is carried out using sulfur released from the sulfur filter media that can release boron and magnesium as an electron donor, achieving nitrate removal, generating nitrogen gas, and forming sulfate in the wastewater, consuming dissolved oxygen, and sulfate-reducing bacteria reduce some sulfate to hydrogen sulfide under anaerobic or hypoxic conditions; in the upper part of the reaction zone, sulfur autotrophic denitrification continues, causing the pH to drop to 5.75- At a pH range of 6.85, the release of iron, boron, and magnesium elements in the filter media can be promoted. On the one hand, iron ions will react with phosphate to form precipitates, achieving deep phosphorus removal. On the other hand, the released boron and magnesium elements are absorbed by plants, promoting root growth, strengthening the root oxygen secretion process, and forming multiple micro-zones containing dissolved oxygen. Furthermore, these dissolved oxygens will re-oxidize the hydrogen sulfide produced by reduction, producing elemental sulfur or sulfate, thus reducing the amount of hydrogen sulfide. Elemental sulfur further promotes the process of sulfur autotrophic denitrification. The dissolved oxygen concentration monitored by the pH and dissolved oxygen probes is between 0.5 and 0.8 mg / L.

[0026] The ammonia nitrogen content of the effluent through the outlet is 0.3±0.2 mg / L, the nitrate content is 0.6±0.3 mg / L, and the phosphate content is 0.1±0.1 mg / L.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The system of this invention employs a coupled process technology of sulfur autotrophic denitrification and constructed wetlands. Compared with traditional heterotrophic denitrification, it can achieve deep denitrification of low-carbon wastewater with a low carbon-to-nitrogen ratio, such as urban domestic sewage, including effluent from urban sewage treatment plants that does not contain biodegradable organic matter. It achieves zero external carbon source addition, saving 100% of carbon source addition costs. The sludge production of autotrophic bacteria is reduced by 87% compared to heterotrophic bacteria. The effluent quality can stably meet the Class IV water quality standards of the Chinese Surface Water Environmental Standard, demonstrating good environmental and economic benefits.

[0029] The system of this invention is equipped with a buffer zone, which allows for the regulation of the water intake to the reaction zone. This enables the reaction zone to resist the impact of fluctuations in the water intake load, ensuring long-term operational stability. The operating and maintenance costs are reduced by 45% compared to heterotrophic denitrification systems that use sodium acetate as an external carbon source, and the system has a wide range of applications.

[0030] This sulfur-containing filter media, capable of releasing boron and magnesium, is prepared by fully utilizing industrial waste rich in boron, magnesium, and sulfur. The released boron and magnesium elements enhance oxygen secretion from plant roots in the constructed wetland system, creating an aerobic microzone in the upper part of the reaction zone with dissolved oxygen levels around 0.5–0.8 mg / L. This effectively reduces hydrogen sulfide generated from the oxidation of sulfate ions, with a hydrogen sulfide yield below 0.5 ppm. The resulting product is elemental sulfur or sulfate ions, which can then serve as a sulfur source to further promote sulfur autotrophic denitrification. Attached Figure Description

[0031] Figure 1 This is a structural diagram of the boron-magnesium enhanced plant oxygen secretion artificial wetland system of the present invention, which achieves sulfur autotrophy, nitrogen and phosphorus removal, and hydrogen sulfide reduction.

[0032] Figure 2 This is a structural diagram of a porous plate used for supporting filter media and distributing water evenly.

[0033] In the diagram, 1-water inlet tank, 2-water inlet pipe, 3-peristaltic pump, 4-water inlet, 5-main body of wetland system, 6-wetland plants, 7-hollow pipe, 8-pH and dissolved oxygen combined monitoring instrument, 9-pH and dissolved oxygen probe, 10-water sample sampling port, 11-filter media sampling port, 12-sulfur filter media, 13-porous plate, 14-water outlet, 15-water outlet pipe, 16-water outlet tank, 17-air inlet, Ⅰ-reaction zone, Ⅱ-buffer zone. Detailed Implementation

[0034] The accompanying drawings are for illustrative purposes only. Directional terms in the drawings, such as "up," "down," "left," "right," "inner," "outer," and "side," are merely illustrative based on the drawings and do not represent actual locations. The technical solution of the present invention will be fully and thoroughly described below in conjunction with the accompanying drawings and embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, the boron-magnesium enhanced plant oxygen secretion artificial wetland system realizes sulfur autotrophy, denitrification, phosphorus removal and hydrogen sulfide reduction, including a vertical flow wetland system body 5. The wetland system body 5 includes a bottom buffer zone II and an upper reaction zone I, separated by a porous plate 13 for filter media support and uniform water distribution.

[0037] The buffer zone II is equipped with a base for placing the entire system body. The upper layer of the base is a cylindrical area with an inlet 4 on its side. Above the cylindrical area is a perforated plate 13. Above the perforated plate 13 is the reaction zone I, where the filter media is a mixture of boron-magnesium-releasing sulfur filter media 12 and quartz sand in a 4:1 ratio. The top of the reaction zone I is open for planting wetland plants. An outlet 14 is located on the side wall of the reaction zone I near the top opening. The roots of the wetland plants 6 are located at the outlet 14 (or, when planting the wetland plants 6, the roots of the wetland plants 6 are located in the area above and below the outlet of the reaction zone).

[0038] A row of water sample sampling ports 10 is evenly arranged from bottom to top on the side wall of reaction zone I, and five water sample sampling ports 10 are evenly arranged; a row of filter media sampling ports 11 is evenly arranged from bottom to top on the side wall of reaction zone I, and five filter media sampling ports 11 are evenly spaced.

[0039] A hollow tube 7 is installed in the center of the reaction zone I, with its top end higher than the top end of the reaction zone I. The hollow tube 7 is a PVC pipe with several evenly distributed small holes. A pH and dissolved oxygen probe 9 is placed inside the hollow tube 7, and the pH and dissolved oxygen probe 9 is connected to a pH and dissolved oxygen combined monitoring instrument 8 via wires.

[0040] The inlet 4 of the main body of the wetland system is connected to the inlet tank 1 via a peristaltic pump 3, and its outlet 14 is connected to the outlet tank 16 via an outlet pipe 15.

[0041] The sulfur filter media 12 that can release boron and magnesium is prepared using waste materials containing sulfur, iron, boron and magnesium generated in industrial production, especially waste materials containing more boron and magnesium. When the pH in the upper part of reaction zone I reaches 5.75-6.85, it can promote the release of boron and magnesium elements, promote plant root growth, and enhance the root oxygen secretion process.

[0042] The diameter of reaction zone I is equal to the diameter of buffer zone II, and the height ratio of buffer zone II to reaction zone I is 1:6. For example... Figure 2 As shown, the porous plate 13 is a circular plate with a certain thickness (the thickness is set according to actual needs). It has two circumferences. The diameter of the inner circumference is adapted to the diameter of the buffer zone II and the reaction zone I. Several water distribution holes are evenly arranged on the inner circumference for supporting the filter media and distributing water evenly. The diameter of the outer circumference of the porous plate 13 is larger than the diameter of the reaction zone I. The connection between the porous plate 13 and the buffer zone II and the reaction zone I is a closed connection, which is achieved using existing technology.

[0043] The operation method of a boron-magnesium enhanced plant oxygen secretion constructed wetland system to achieve sulfur autotrophy, nitrogen and phosphorus removal, and hydrogen sulfide reduction includes the following steps:

[0044] (1) Connect the water inlet tank 1, peristaltic pump 3, and wetland system body 5 through the water inlet pipe 2. The water inlet pipe 2 is connected to the water inlet 4 of buffer zone II. Connect the wetland system body 5 and water outlet tank 16 through the water outlet pipe 15. The water outlet pipe 15 is connected from the water outlet 14 of reaction zone I to the water outlet tank 16.

[0045] (2) The constructed wetland system provided in this embodiment is started by inoculating residual sludge from the secondary sedimentation tank of a municipal wastewater treatment plant. The effluent from the municipal wastewater treatment plant is used as the wetland system influent, mainly containing ammonia nitrogen (<5 mg / L, 1.6±2.3 mg / L), nitrate (<15 mg / L, 5.6±8.2 mg / L), and phosphate (<0.5 mg / L, 0.2±0.2 mg / L). The peristaltic pump 3 is started, and wastewater enters the buffer zone II of the main body 5 of the wetland system from the influent tank 1 through the influent pipe 2. The influent flow is continuous. After passing through the perforated plate 13 supported by filter media and evenly distributed with water, it enters the reaction zone I. In the reaction zone, nitrogen and phosphorus pollutants are removed from bottom to top through sulfur filter media that can release boron and magnesium. The specific method is as follows:

[0046] In the lower part of reaction zone I, some dissolved oxygen is introduced into the influent, causing nitrification, which consumes dissolved oxygen and converts ammonia nitrogen into nitrate. In the middle part of reaction zone I, an autotrophic denitrification process takes place, using sulfur released from sulfur filter media that can release boron and magnesium as an electron donor, to remove nitrate, produce nitrogen gas, and form sulfate in the wastewater. Dissolved oxygen is consumed, and sulfate-reducing bacteria reduce some of the sulfate to hydrogen sulfide under anaerobic or anoxic conditions. In the upper part of reaction zone I, sulfur autotrophic denitrification continues, causing the pH to drop to 5.75-6. At 85%, the release of iron, boron, and magnesium from the filter media is promoted. On the one hand, iron ions react with phosphates to form precipitates, achieving deep phosphorus removal. On the other hand, the released boron and magnesium are absorbed by plants, promoting root growth, enhancing root oxygen secretion, and forming multiple micro-zones containing dissolved oxygen. This dissolved oxygen will further oxidize the hydrogen sulfide produced by reduction, producing elemental sulfur or sulfate, thus reducing the amount of hydrogen sulfide. Elemental sulfur further promotes the autotrophic denitrification process. The dissolved oxygen concentration monitored by pH and dissolved oxygen probes is 0.5 mg / L. In addition, during the growth process, the roots of plants in the constructed wetland system release organic exudates into the rhizosphere, driving part of the heterotrophic denitrification process. At the same time, the absorption by plant roots and the adsorption by the filter media also enhance the absorption and removal of nitrogen and phosphorus pollutants.

[0047] pH and dissolved oxygen probe 9 monitors the pH value and dissolved oxygen concentration in hollow tube 7 in real time and transmits the data to pH and dissolved oxygen combined monitor 8 for display; the water retention time is 4.5h.

[0048] (3) The purified wastewater flows from the outlet 14 of the reaction zone through the outlet pipe 15 into the outlet tank 16 and is discharged into the natural water body. The ammonia nitrogen content of the effluent through the outlet 14 is 0.3±0.2mg / L, the nitrate content is 0.6±0.3mg / L, and the phosphate content is 0.1±0.1mg / L.

[0049] Natural water bodies have relatively fast flow rates, and the waterfalls created by the drop in elevation provide ample dissolved oxygen, making it difficult for sulfates to be reduced to hydrogen sulfide and causing black and odorous water. This results in good ecological and environmental benefits and can be used for deep denitrification of wastewater in ecologically sensitive areas. In addition to treating effluent from urban wastewater treatment plants, this invention can also be applied to treat secondary biological treatment effluent from urban wastewater, and parameters such as hydraulic retention time can be adjusted accordingly based on operational conditions.

[0050] Example 2

[0051] A boron-magnesium enhanced plant oxygen secretion artificial wetland system for sulfur autotrophy, denitrification, phosphorus removal, and hydrogen sulfide reduction includes a vertical flow wetland system body 5. The wetland system body 5 includes a bottom buffer zone II and an upper reaction zone I, separated by a porous plate 13 for filter media support and uniform water distribution.

[0052] like Figure 1 As shown, the buffer zone II is equipped with a base for placing the entire system body. The upper part of the base is a cylindrical area, with a water inlet 4 on the side of the cylindrical area. An air inlet 17 is located on the opposite side of the water inlet 4 for connecting an aeration pump (not shown in the figure). If fluctuations occur during the operation of the constructed wetland system, such as insufficient oxygen secretion by wetland plants, air can be injected into the buffer zone II through the aeration pump. The air is transported upward through the perforated plate 13 to replenish dissolved oxygen. A flow meter is installed on the connecting pipe of the aeration pump, and the aeration rate can be adjusted in real time by monitoring the pH and dissolved oxygen probes.

[0053] A row of six water sample sampling ports 10 are evenly arranged from bottom to top on the side wall of the reaction zone; a row of six filter media sampling ports 11 are evenly arranged from bottom to top on the side wall of the reaction zone.

[0054] The ratio of sulfur filter media 12, which can release boron and magnesium, to quartz sand in the filter media is 3:1.

[0055] Preferably, the diameter of reaction zone I is equal to the diameter of buffer zone II, and the height ratio of buffer zone to reaction zone I is 1:8.

[0056] The operation method of a boron-magnesium enhanced plant oxygen secretion constructed wetland system to achieve sulfur autotrophy, nitrogen and phosphorus removal, and hydrogen sulfide reduction includes the following steps:

[0057] (1) Connect the water inlet tank 1, peristaltic pump 3, and wetland system main body 5 through water inlet pipe 2. Water inlet pipe 2 is connected to water inlet 4 of buffer zone II. Connect the wetland system main body 5 and water outlet tank 16 through water outlet pipe 15. Water outlet pipe 15 is connected from water outlet 14 of reaction zone I to water outlet tank 16. Air inlet 17 is connected to aeration pump through air inlet pipe (when air inlet 17 is not in use, it is plugged with a sealable plug).

[0058] (2) Start the peristaltic pump 3. The sewage enters the buffer zone II of the wetland system 5 from the inlet tank 1 through the inlet pipe 2. The water inlet is continuous flow. After passing through the filter media and the porous plate 13 that distributes water evenly, it enters the reaction zone I. In the reaction zone, nitrogen and phosphorus pollutants are removed from bottom to top through the sulfur filter media 12 that can release boron and magnesium.

[0059] pH and dissolved oxygen probe 9 monitors the pH value and dissolved oxygen concentration in hollow tube 7 in real time and transmits the data to pH and dissolved oxygen combined monitor 8 for display. When the dissolved oxygen concentration monitored by pH and dissolved oxygen probe 9 is relatively low, the aeration pump is turned on to introduce air. The air is transmitted upward through the perforated plate to replenish dissolved oxygen and make the dissolved oxygen concentration about 0.8 mg / L. The water retention time is 3 hours.

[0060] (3) The purified wastewater flows from the outlet 14 of the reaction zone through the outlet pipe 15 into the outlet tank 16 and is discharged into the natural water body. The ammonia nitrogen content of the effluent through the outlet 14 is 0.3±0.1mg / L, the nitrate content is 0.6±0.1mg / L, and the phosphate content is 0.1±0.1mg / L.

[0061] Other areas not mentioned are the same as in Example 1.

[0062] Example 3

[0063] A boron-magnesium enhanced plant oxygen secretion artificial wetland system for sulfur autotrophy, denitrification, phosphorus removal, and hydrogen sulfide reduction includes a vertical flow wetland system body 5. The wetland system body 5 includes a bottom buffer zone II and an upper reaction zone I, separated by a porous plate 13 for filter media support and uniform water distribution.

[0064] The buffer zone II is equipped with a base for placing the entire system body. The upper layer of the base is a cylindrical area, with water inlets 4 located on the side of the cylindrical area. If fluctuations occur during the operation of the constructed wetland system, such as insufficient oxygen secretion by wetland plants, wetland plants can be selected appropriately according to the application scenario. Planting plants with large leaf areas can double the leaf area, increasing root oxygen secretion by 70%, which can reduce the amount of hydrogen sulfide produced through oxidation. Dissolved oxygen levels are monitored in real time using pH and dissolved oxygen probes 9.

[0065] A row of water sample sampling ports 10 is evenly arranged from bottom to top on the side wall of the reaction zone, and four water sample sampling ports 10 are evenly arranged; a row of filter media sampling ports 11 is evenly arranged from bottom to top on the side wall of the reaction zone, and four filter media sampling ports 11 are evenly spaced.

[0066] The ratio of sulfur filter media 12, which can release boron and magnesium, to quartz sand in the filter media is 5:1.

[0067] The diameter of reaction zone I is equal to the diameter of buffer zone II, and the height ratio of buffer zone II to reaction zone I is 1:10.

[0068] Other areas not mentioned are the same as in Example 1.

[0069] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation", "connection", "linking", etc., should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for operating an artificial wetland system that enhances plant oxygen secretion to achieve sulfur autotrophic denitrification, phosphorus removal, and hydrogen sulfide reduction. The method is characterized by the following: The system includes a vertical flow wetland system body, which includes a bottom buffer zone and an upper reaction zone, separated by a perforated plate. The buffer zone is equipped with a base, and an inlet is provided on the side of the upper area of ​​the base. The upper layer of the buffer zone is a perforated plate. The upper layer of the perforated plate is a reaction zone, in which sulfur filter media and quartz sand that can release boron and magnesium are added. The top of the reaction zone is open for planting wetland plants. An outlet is provided on the side wall of the reaction zone near the top opening. A hollow tube is set in the center of the reaction zone, and a pH and dissolved oxygen probe is placed inside the hollow tube. The pH and dissolved oxygen probe is connected to a pH and dissolved oxygen combined monitoring instrument through wires. The boron-magnesium-releasing sulfur filter material is uniformly mixed with quartz sand in a ratio of 3 to 5:

1. The boron-magnesium-releasing sulfur filter material is prepared using waste materials containing sulfur, iron, boron and magnesium generated in industrial production. The inlet of the main body of the wetland system is connected to the inlet tank via a peristaltic pump, and its outlet is connected to the outlet tank. The operating method includes the following steps: (1) Connect the water inlet tank, peristaltic pump, and wetland system body through the water inlet pipe, and connect the water inlet pipe to the water inlet of the buffer zone; connect the wetland system body and water outlet tank through the water outlet pipe, and connect the water outlet pipe from the water outlet of the reaction zone to the water outlet tank; (2) Start the peristaltic pump. The sewage enters the buffer zone of the main body of the wetland system from the inlet tank through the inlet pipe. The water inlet is continuous flow. After passing through the perforated plate, it enters the reaction zone. In the reaction zone, nitrogen and phosphorus pollutants are removed from bottom to top through sulfur filter media that can release boron and magnesium. The pH and dissolved oxygen probes monitor the pH value and dissolved oxygen concentration in the hollow tube in real time. The water retention time is 2 to 4.5 hours. (3) The purified wastewater flows from the outlet of the reaction zone through the outlet pipe into the outlet bucket and is discharged into the natural water body; In step (2), in the lower part of the reaction zone, some dissolved oxygen is introduced into the influent, causing nitrification, which consumes dissolved oxygen and converts ammonia nitrogen into nitrate. In the middle of the reaction zone, an autotrophic denitrification process is carried out using sulfur released from sulfur filter media that can release boron and magnesium as an electron donor to remove nitrate, generate nitrogen gas, and form sulfate in the wastewater. Dissolved oxygen is consumed, and sulfate-reducing bacteria reduce some sulfate to hydrogen sulfide under anaerobic or hypoxic conditions. In the upper part of the reaction zone, sulfur autotrophic denitrification continues, causing the pH to drop. With a pH of 5.75-6.85, it promotes the release of iron, boron, and magnesium elements from the sulfur filter media. Iron ions react with phosphate to form precipitates, achieving deep phosphorus removal. The released boron and magnesium elements are absorbed by plants, promoting root growth and enhancing root oxygen secretion. This creates multiple micro-zones containing dissolved oxygen, which then re-oxidizes the hydrogen sulfide produced by reduction, generating elemental sulfur or sulfate, thus reducing the amount of hydrogen sulfide. The elemental sulfur further promotes the autotrophic denitrification process. The dissolved oxygen concentration monitored by the pH and dissolved oxygen probes is between 0.5 and 0.8 mg / L.

2. The operation method of the constructed wetland system for sulfur autotrophic denitrification, phosphorus removal, and hydrogen sulfide reduction achieved by enhancing plant oxygen secretion with boron and magnesium as described in claim 1, characterized in that, The reaction zone is cylindrical, and a row of filter media sampling ports is evenly arranged on its sidewall from bottom to top. At least two filter media sampling ports are provided.

3. The operation method of the constructed wetland system for achieving sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction by enhancing plant oxygen secretion according to claim 2, characterized in that, A water sampling port is uniformly arranged from bottom to top on the side wall of the reaction zone, and at least two water sampling ports are provided.

4. The operation method of the constructed wetland system for achieving sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction by enhancing plant oxygen secretion according to claim 3, characterized in that, Except for the base portion, the buffer zone is cylindrical. The diameter of the cylindrical reaction zone is equal to the diameter of the cylindrical buffer zone, and the height ratio of the buffer zone to the reaction zone is 1:3 to 20. An air inlet is provided on the opposite side of the water inlet of the buffer zone, and the air inlet is connected to an aeration pump.

5. The operation method of the constructed wetland system for achieving sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction by enhancing plant oxygen secretion according to claim 4, characterized in that, The porous plate is a circular plate with a certain thickness, with two circumferences. The diameter of the inner circumference is matched with the diameter of the buffer zone and the reaction zone. Several water distribution holes are evenly arranged in the inner circle for supporting the filter media and distributing water evenly. The diameter of the outer circumference of the porous plate is larger than the diameter of the reaction zone and the buffer zone, and the connection between the porous plate and the reaction zone and the buffer zone is a closed connection. The diameter of the water distribution holes is smaller than the diameter of the sulfur filter media particles that can release boron and magnesium.

6. The operation method of the constructed wetland system for achieving sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction by enhancing plant oxygen secretion according to claim 1, characterized in that, The roots of the wetland plants are located at the water outlet.

7. The operation method of the constructed wetland system for achieving sulfur autotrophy, nitrogen removal, phosphorus removal, and hydrogen sulfide reduction by enhancing plant oxygen secretion according to claim 1, characterized in that, The top of the hollow tube is higher than the top of the reaction zone. The hollow tube is a PVC pipe with several small holes evenly distributed on it.

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