Constructed wetland system for enhancing plant-accumulation of antibiotics and deep denitrification by sulfur-iron cycle and operation method thereof

Abstract

The present application belongs to the technical field of rural sewage treatment, and specifically discloses a kind of assembly type constructed wetland system for sulfur-iron cycle enhanced plant enrichment of antibiotics and deep denitrification and a method for operating the same.The present application is used to solve the problems of high cost, high carbon consumption and secondary pollution in the existing deep treatment technology of rural sewage containing antibiotics and nitrogen pollutants.The wetland system comprises a housing, a backwashing pump and a multi-parameter measurement and control instrument, and the housing is internally provided with, from left to right, a water inlet area, an upward-flow constructed wetland area, a buffer area, a downward-flow constructed wetland area and a water outlet area arranged side by side.The present application, on one hand, utilizes sulfur-iron source to enhance the ability of wetland plants to enrich antibiotics, and absorbs the antibiotics in the sewage into the wetland plant body;on the other hand, utilizes sulfur-iron as an electron donor for short-term denitrification, and realizes deep removal of ammonia nitrogen through anaerobic ammonia oxidation, so that the effluent water quality meets the Class IV water quality standard of Chinese surface water environment.

Description

Technical Field

[0001] This invention belongs to the field of rural sewage treatment technology, and in particular relates to a prefabricated constructed wetland system and its operation method that enhances antibiotic enrichment and deep denitrification by sulfur-iron cycling. Background Technology

[0002] The main sources of rural sewage in my country include domestic sewage, agricultural wastewater, and livestock wastewater. Rural sewage contains large amounts of nitrogenous pollutants and antibiotic residues. Antibiotics are a newly emerging type of micropollutant, widely present in various environmental media. Due to the lack of sewage collection networks and treatment facilities in rural areas, and with the increasing volume of rural sewage discharge year by year, coupled with the irrational use of pesticides in rural areas, nitrogenous pollutants and antibiotics can enter the rural environment through multiple pathways, threatening the rural ecological environment.

[0003] Antibiotics are highly ecotoxic and can promote the generation, transfer, and spread of antibiotic resistance genes. On the one hand, they harm the growth and reproduction of aquatic and terrestrial plants and animals, affecting the entire food chain; on the other hand, they lead to the gradual development of antibiotic resistance in bacteria and other microorganisms, posing serious potential threats to human health and the ecological environment. Furthermore, long-term exposure to low doses of antibiotics can cause allergic reactions and poisoning in humans. Some antibiotics severely interfere with various physiological functions in humans and have carcinogenic, teratogenic, and mutagenic effects. Currently, various treatment technologies exist for antibiotic removal, such as adsorption, photodegradation, and advanced oxidation. However, the complexity, high cost, and potential for secondary pollution associated with these methods limit their widespread application.

[0004] Excessive discharge of nitrogenous pollutants into natural water bodies causes environmental problems such as eutrophication and black and odorous water. Traditional denitrification processes consume large amounts of external carbon sources, resulting in high operating costs and increased carbon emissions. Anaerobic ammonium oxidation (ANAO) has attracted widespread attention due to its advantage of achieving deep denitrification without the need for external carbon sources. Ammonia nitrogen and nitrite nitrogen can be synergistically removed by anammox bacteria, but nitrates, accounting for 11% of the total nitrogen removed, are produced, resulting in a theoretical total nitrogen removal rate of only 89% for ANAO. Sulfoferric autotrophic denitrification uses reduced ferroferric sulfate as an electron donor. In an anaerobic environment, it can reduce nitrates produced by ANAO to nitrites, thus providing a stable substrate for ANAO and improving overall denitrification efficiency. Coupled with ANAO, ferroferric autotrophic denitrification can replace carbon sources with ferroferric sulfate, achieving low-carbon deep denitrification. Summary of the Invention

[0005] One objective of this invention is to provide a prefabricated constructed wetland system that enhances antibiotic enrichment and deep denitrification through sulfur-iron cycling, effectively addressing the problems of high cost, high carbon consumption, and easy secondary pollution associated with existing deep treatment technologies for rural wastewater containing antibiotics and nitrogenous pollutants.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A prefabricated constructed wetland system for enhancing plant antibiotic enrichment and deep denitrification through sulfur-iron cycling includes a shell, two backwash pumps, and a multi-parameter monitoring and control instrument for regulating inlet and outlet water flow. The shell contains, from left to right, parallelly arranged inlet, upflow constructed wetland, buffer zone, downflow constructed wetland, and outlet zones, separated by partition walls. The water levels in the inlet, upflow, downflow, and outlet zones decrease sequentially. The water level in the upflow constructed wetland is higher than the water level in the buffer zone, and the water level in the buffer zone is not lower than the water level in the downflow constructed wetland.

[0008] Both the upflow and downflow artificial wetlands consist of a support layer, a filler layer, a plant root layer, and an emergent aquatic plant layer, from bottom to top. The filler layer and plant root layer of the upflow artificial wetland are filled with iron ore filter media, while the filler layer and plant root layer of the downflow artificial wetland are filled with sulfur-iron-based filter media.

[0009] The water inlet area includes a water inlet pool, a water inlet, and a water distribution pipe. The water inlet is located at the lower part of the partition wall between the water inlet area and the upflow artificial wetland area. The inlet of the water distribution pipe is connected to the water inlet. The water distribution pipe is located on the support layer of the upflow artificial wetland area. A water inlet valve is provided at the water inlet for controlling the opening and closing of the water inlet.

[0010] The buffer zone is equipped with through-wall pipes on both the left and right partition walls. The through-wall pipe on the left partition wall is positioned at the same level as the liquid level in the upward flow artificial wet area, while the through-wall pipe on the right partition wall is positioned at the same level as the liquid level in the downward flow artificial wet area.

[0011] The water outlet area includes a water outlet, a water collection tank, and a water collection pipe. The water outlet is located at the lower part of the partition wall between the downflow constructed wetland area and the water outlet area. The outlet of the water collection pipe is connected to the water outlet. The water collection pipe is located on the support layer of the downflow constructed wetland area. A water outlet valve is provided at the water outlet for controlling the opening and closing of the water outlet.

[0012] The two backwash pumps are connected to the inlet of the inlet water distribution pipe and the outlet of the outlet water collection pipe, respectively.

[0013] The inlet area, buffer zone, and outlet area are all equipped with level sensors for real-time monitoring of the liquid level. The upflow and downflow artificial wetlands are all equipped with temperature / dissolved oxygen monitors for real-time monitoring of temperature and dissolved oxygen. The level sensors, temperature / dissolved oxygen monitors, inlet valves, and outlet valves are all connected to a multi-parameter measuring and controlling instrument.

[0014] Furthermore, the thicknesses of the filler layer and the plant root layer in the upward flow artificial wetland are 70–100 cm and 30–40 cm, respectively, both filled with iron ore filter media prepared from iron tailings with a particle size of 5–10 mm, the main components of which are zero-valent iron, Fe2O3 and Fe3O4.

[0015] The thickness of the filler layer and the plant root layer in the downflow artificial wetland are 70-100cm and 30-40cm, respectively. Both are filled with sulfur-iron-based filter media made from sulfur solid waste and iron tailings with a particle size of 5-10mm. The main components are elemental sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4.

[0016] Furthermore, the outer surface of the partition wall panel is provided with a geotextile waterproof layer.

[0017] Furthermore, the supporting layer of both the upward flow artificial wetland area and the downward flow artificial wetland area has a thickness of 20cm and is filled with gravel with a particle size of 20-40mm.

[0018] Furthermore, the emergent aquatic plant layer in the upflow and downflow artificial wetlands is planted with wetland plants that have well-developed root systems, strong oxygen secretion capacity, and good stress resistance, including but not limited to yellow iris, reeds, and rush.

[0019] Furthermore, both the inlet water distribution pipe and the outlet water collection pipe include a main pipe and multiple branch pipes. The branch pipes are evenly distributed on both sides of the main pipe, and the branch pipes on the same side are arranged in parallel. Both the main pipe and the branch pipes are provided with multiple inlet and outlet holes at equal intervals along their respective axial directions.

[0020] Another objective of this invention is to provide an operation method for the assembled constructed wetland system described in the above embodiments, which enhances plant antibiotic enrichment and deep denitrification through sulfur-iron cycling, comprising three steps: startup, operation, and maintenance.

[0021] S1. For the start-up process: Use the residual sludge from the wastewater treatment plant as seed sludge, control the sludge concentration in the upflow and downflow constructed wetlands to be between 1000 and 1500 mg / L, and use a backwash pump to pump the diluted seed sludge into the upflow and downflow constructed wetlands through the inlet water distribution pipe and the outlet water collection pipe, respectively, until the liquid surface covers the roots of the wetland plants, in order to start the constructed wetland system.

[0022] S2. The operation process includes the following steps: S21. Wastewater is used as the influent of the constructed wetland system. The wastewater is stored in the influent area. When the liquid level in the influent area is higher than the liquid level in the upflow constructed wetland area, the influent valve is opened by controlling the multi-parameter measuring and control instrument to make the wastewater flow evenly into the upflow constructed wetland area to remove antibiotics from the wastewater.

[0023] S22. Wastewater flows into the buffer zone through the through-wall pipe located on the left side of the buffer zone and is stored there. When the liquid level in the buffer zone is higher than that in the through-wall pipe located on the right side of the buffer zone, the wastewater with uniform water quality flows from the through-wall pipe located on the right side of the buffer zone to the downflow artificial wet area.

[0024] S23. Wastewater flows from top to bottom through the plant root layer, filler layer and support layer of the downflow constructed wetland. Under the action of oxygen secretion from the roots of wetland plants, the wastewater gradually transitions from an aerobic environment to an anaerobic or hypoxic environment, so that nitrification, denitrification and anaerobic ammonia oxidation occur simultaneously in the wetland. Phosphorus in the wastewater is removed through absorption, assimilation and precipitation by wetland plants.

[0025] S24. The treated wastewater is collected by the effluent collection pipe and flows into the collection pool through the effluent outlet. The effluent water quality meets the requirements of Class IV surface water quality standards in China.

[0026] S3. Regarding the maintenance process: First, we can determine whether there is a blockage by monitoring the liquid level in different areas of the constructed wetland system. Second, we can determine the removal rate of antibiotics absorbed by wetland plants by monitoring the concentration of antibiotics in the influent and effluent.

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

[0028] (1) In an upflow constructed wetland, the iron ore filter media can release iron ions and, under the action of rhizosphere microorganisms, form an iron film with a thickness of 0.2-0.5 mm at the roots of wetland plants, thereby enhancing the ability of wetland plant roots to absorb antibiotics and maintaining an antibiotic removal rate of over 85%. No chemical additives are required, and compared with advanced oxidation methods, the treatment cost is reduced by 80%, with no secondary pollution.

[0029] (2) In the downflow constructed wetland area, the present invention creates an aerobic-anoxic-anaerobic wetland environment from top to bottom under the action of oxygen secretion from the roots of wetland plants, so that nitrogen can be removed synergistically through nitrification, denitrification and anaerobic ammonium oxidation. The sulfur / iron autotrophic denitrification coupled with anaerobic ammonium oxidation technology can achieve zero addition of external carbon sources, avoiding the drawback of excessive nitrate production in the single anaerobic ammonium oxidation process, and the effluent quality can stably meet the Class IV water quality standard of China's surface water environment. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the artificial wetland system of the present invention.

[0031] Figure 2 yes Figure 1 A cross-sectional view along line AA, where the hollow arrow indicates the direction of water flow.

[0032] Figure 3 This is a schematic diagram of the structure of the inlet water distribution pipe (or outlet water collection pipe).

[0033] List of reference numerals in the attached diagram: Shell-1; Backwash pump-2; Multi-parameter controller-3; Partition wall-4; Inlet tank-5; Inlet port-6; Inlet water distribution pipe-7; Outlet port-8; Collection tank-9; Outlet water collection pipe-10; Main pipeline-11; Branch pipeline-12; Inlet / outlet water hole-13; Through-wall pipe-14; Liquid level sensor-15; Temperature / dissolved oxygen monitor-16; Wetland plants-17; Inlet zone-I; Upflow artificial wetland area-II; Buffer zone-III; Downflow artificial wetland area-IV; Outlet zone-V; Support layer-i; Filler layer-ii; Plant root layer-iii; Emergent aquatic plant layer-iv. Detailed Implementation

[0034] Example 1: A modular constructed wetland system that enhances antibiotic enrichment and deep denitrification through sulfur-iron cycling, such as... Figure 1 and Figure 2 As shown, the system includes a housing 1, two backwash pumps 2, and a multi-parameter monitoring and control instrument 3 for regulating the inlet and outlet water flow rates. The housing 1 is composed of a stainless steel frame and steel plates. Inside the housing 1, from left to right, are arranged in parallel sections separated by lightweight partition walls 4: an inlet zone I, an upward-flowing artificial wetland zone II, a buffer zone III, a downward-flowing artificial wetland zone IV, and an outlet zone V. The liquid levels in the inlet zone I, upward-flowing artificial wetland zone II, downward-flowing artificial wetland zone IV, and outlet zone V decrease sequentially. The liquid level in the upward-flowing artificial wetland zone II is higher than the liquid level in the buffer zone III, and the liquid level in the buffer zone III is not lower than the liquid level in the downward-flowing artificial wetland zone IV. In this embodiment, the outer surface of the lightweight partition wall 4 is provided with a geotextile waterproof layer.

[0035] The water inlet area I includes a water inlet pool 5, a water inlet 6, and a water distribution pipe 7. The water inlet 6 is located at the lower part of the lightweight partition wall 4 between the water inlet area I and the upward flow constructed wetland area II. The inlet of the water distribution pipe 7 is connected to the water inlet 6. The water distribution pipe 7 is located on the support layer i of the upward flow constructed wetland area II. A water inlet valve is provided at the water inlet 6 to control the opening and closing of the water inlet 6.

[0036] The water outlet zone V includes an outlet 8, a water collection tank 9, and an outlet water collection pipe 10. The outlet 8 is located at the lower part of the lightweight partition wall 4 between the downflow constructed wetland zone IV and the water outlet zone V. The outlet of the outlet water collection pipe 10 is connected to the outlet 8. The outlet water collection pipe 10 is located on the support layer i of the downflow constructed wetland zone IV. An outlet valve is provided at the outlet 8 to control the opening and closing of the outlet 8.

[0037] Two backwash pumps 2 are connected to the inlet of the inlet water distribution pipe 7 and the outlet of the outlet water collection pipe 10, respectively. In this embodiment, as... Figure 3 As shown, both the inlet water distribution pipe 7 and the outlet water collection pipe 10 include a main pipe 11 and multiple branch pipes 12. The main pipe 11 is a PVC pipe with an inner diameter of 10 cm, and 10 inlet and outlet holes 13 with a diameter of 15 mm are evenly spaced along its axial direction. The branch pipes 12 are evenly distributed on both sides of the main pipe 11, and the branch pipes 12 on the same side are arranged in parallel. The branch pipes 12 are PVC pipes with an inner diameter of 6 cm, and 8 inlet and outlet holes 13 with a diameter of 10 mm are evenly spaced along their axial direction. The structural arrangement of the inlet water distribution pipe 7 and the outlet water collection pipe 10 is conducive to both uniform water distribution and collection, and also to the replenishment of the filler layer ii matrix with water flow in the form of microparticles (particle size of about 100 micrometers).

[0038] Buffer zone III primarily serves a buffering function to achieve uniform water distribution. Through-wall pipes 14 are installed on both the left and right lightweight partition walls 4 of buffer zone III. The through-wall pipe 14 on the left partition wall 4 of buffer zone III is positioned at the same level as the liquid level in the upward-flowing artificial wetland area II, while the through-wall pipe 14 on the right partition wall 4 of buffer zone III is positioned at the same level as the liquid level in the downward-flowing artificial wetland area IV. In this embodiment, the through-wall pipe 14 is a PVC pipe with an inner diameter of 15cm.

[0039] The inlet zone I, buffer zone III, and outlet zone V are all equipped with level sensors 15 for real-time monitoring of the liquid level. The upflow constructed wetland zone II and the downflow constructed wetland zone IV are each equipped with temperature / dissolved oxygen monitors 16 for real-time monitoring of temperature and dissolved oxygen. The level sensors 15, temperature / dissolved oxygen monitors 16, inlet valves, and outlet valves are all connected to the multi-parameter measuring and controlling instrument 3.

[0040] Both the upflow constructed wetland II and the downflow constructed wetland IV consist of, from bottom to top, a support layer i, a filler layer ii, a plant root layer iii, and an emergent aquatic plant layer iv. In this embodiment, the thicknesses of the filler layer ii and the plant root layer iii in the upflow constructed wetland II are 70–100 cm and 30–40 cm, respectively. Both are filled with iron ore filter media prepared from iron tailings with a particle size of 5–10 mm. The main components are zero-valent iron, Fe2O3, and Fe3O4, as well as a small amount of CaCO3, etc., mainly for iron cycling enhancement and plant enrichment of antibiotics. The thicknesses of the packing layer ii and the plant root layer iii in the downflow constructed wetland IV are 70–100 cm and 30–40 cm, respectively. Both are filled with sulfur-iron-based filter media prepared from sulfur solid waste and iron tailings with a particle size of 5–10 mm. The main components are elemental sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4, etc., which mainly carry out sulfur-iron cycle enhanced sulfur / iron autotrophic denitrification coupled with anaerobic ammonia oxidation for deep denitrification.

[0041] In this embodiment, the thickness of the support layer i in both the upflow constructed wetland area II and the downflow constructed wetland area IV is 20 cm, and both are filled with gravel with a particle size of 20-40 mm. The emergent aquatic plant layer iv in both the upflow and downflow constructed wetland areas II and IV is planted with wetland plants 17 that have well-developed root systems, strong oxygen secretion capacity, and good stress resistance, such as yellow iris, reeds, and rush, at a planting density of 25 plants / m². 2 .

[0042] This embodiment is used to achieve deep denitrification and synergistic removal of antibiotic pollutants from rural sewage. Specifically, on the one hand, the sulfur-iron source is used to enhance the ability of wetland plant 17 to accumulate antibiotics in its roots, absorbing antibiotics from the sewage into the wetland plant 17, and finally removing the antibiotics by harvesting the wetland plant 17; on the other hand, sulfur-iron is used as an electron donor for short-range denitrification, and the generated nitrite is further removed by anaerobic ammonia oxidation with the ammonia nitrogen in the original sewage. The following embodiment, Example 2, further details the operation method of the assembled constructed wetland system described in Example 1, which uses sulfur-iron cycling to enhance antibiotic accumulation and deep denitrification in wetland plants 17.

[0043] Example 2: An operation method for a prefabricated constructed wetland system with enhanced plant antibiotic enrichment and deep denitrification via sulfur-iron cycling as described in Example 1, comprising three steps: startup, operation, and maintenance.

[0044] (1) For the start-up process: using the residual sludge from the wastewater treatment plant as seed sludge, the sludge concentration in the upflow constructed wetland area II and the downflow constructed wetland area IV is controlled at 1000-1500 mg / L. The mixed activated sludge (i.e., the diluted seed sludge) is pumped into the upflow constructed wetland area II and the downflow constructed wetland area IV through the inlet water distribution pipe 7 and the outlet water collection pipe 10, respectively, until the wetland liquid surface covers the roots of the wetland plants 17, so as to start up the constructed wetland system.

[0045] (2) The operation process includes the following steps: S21, using rural sewage as the influent of the constructed wetland system. The rural sewage mainly contains ammonia nitrogen (21.9±2.1mg / L), nitrate (3.3±3.7mg / L), phosphate (1.7±0.8mg / L), COD (253.2±5.3mg / L) and antibiotics (total concentration of 78.3±0.1~2044.3±52.8ng / L), etc. Among them, the concentrations of tetracycline, quinolone, sulfonamide and macrolide antibiotics are 1756.5±56.4ng / L, 255.7±3.4ng / L, 150.8±2.2ng / L and 67.9±4.6ng / L, respectively.

[0046] Rural sewage is stored in inlet area I. When the liquid level in inlet area I is higher than the liquid level in upflow constructed wetland area II, the inlet valve is opened by the multi-parameter measuring and control instrument 3 to allow the rural sewage to flow evenly into upflow constructed wetland area II to remove antibiotics from the rural sewage.

[0047] Antibiotics in rural sewage are removed through the following process: First, as the water level rises, the sewage flows into the anoxic packing layer ii filled with iron ore filter media. Under the action of microorganisms, antibiotics (such as tetracycline, oxytetracycline, and ofloxacin) act as electron donors, and iron oxides act as electron acceptors, resulting in redox reactions that partially degrade antibiotics. At the same time, high-valence iron ions are reduced to low-valence states, promoting the activity of dissimilatory metal-reducing bacteria and other related microorganisms. Second, as the water level rises to the plant root layer iii, the dissolved oxygen content increases, and the reduced low-valence iron is further oxidized, generating an iron cycle, thereby improving the removal effect of antibiotics. Finally, the roots of wetland plants 17 can enrich antibiotics through surface adsorption and absorption. Bacteria utilize the iron film formed in the rhizosphere by catalase secreted by plants, as well as oxides such as ferric hydroxide produced by the hydrolysis of iron ore filter media, to promote the accumulation of antibiotics in the roots of wetland plants 17. After antibiotics accumulate in the roots of wetland plant 17, most of them are transferred to other tissues of wetland plant 17 through diffusion and plant transpiration, and finally the antibiotics are removed by harvesting wetland plant 17.

[0048] S22. Wastewater flows into buffer zone III through the through-wall pipe 14 located on the left side of buffer zone III and is stored therein. When the liquid level in buffer zone III is higher than that in the through-wall pipe 14 located on the right side of buffer zone III, the wastewater with uniform water quality flows from the through-wall pipe 14 located on the right side of buffer zone III to the downflow artificial wetland area IV.

[0049] S23. Wastewater flows from top to bottom through the plant root layer iii, packing layer ii, and support layer i of the downflow constructed wetland IV. Under the oxygen secretion of the plant roots, the wastewater gradually transitions from an aerobic environment to an anaerobic or hypoxic environment in the lower part of the wetland, thus allowing nitrification, denitrification, and anaerobic ammonium oxidation to occur simultaneously. In the plant root layer iii, sufficient dissolved oxygen provides a favorable growth and reproduction environment for ammonia-oxidizing and nitrite-oxidizing bacteria, converting ammonia nitrogen into nitrate. Simultaneously, some ammonia nitrogen in the wastewater is absorbed by the well-developed root system of wetland plants 17, supplying the growth and development of these plants. Due to the consumption of dissolved oxygen, the packing layer ii, filled with sulfur-iron-based filter media, is mainly in an anaerobic and hypoxic state. In the upper layer of packing layer ii, nitrate in the wastewater is converted into nitrite under sulfur / iron autotrophic short-range denitrification, providing sufficient substrate for anaerobic ammonium oxidation. In the lower layer of packing layer ii, the generated nitrite and ammonia nitrogen in the wastewater are synergistically removed under the action of anaerobic ammonium-oxidizing bacteria. In addition, residual organic matter in the wastewater and organic matter secreted by the roots of 17 wetland plants provide some electron donors, driving heterotrophic denitrification.

[0050] Phosphorus in wastewater is primarily removed through plant absorption, assimilation, and precipitation. Some phosphates in the wastewater are absorbed and assimilated by the roots of wetland plants (layer iii), accumulating in the plants and subsequently removed through harvesting. In the filter media (layer ii), phosphates in the wastewater can react with Fe released from the sulfur-iron filter media. 3+ Precipitate is generated and removed.

[0051] S24. Finally, the treated wastewater is collected by the effluent collection pipe 10 and flows into the collection tank 9 through the effluent outlet 8.

[0052] Under continuous flow operation with a hydraulic retention time of 36 hours, the total concentration of antibiotics in the constructed wetland system decreased to 65.7–408.9 ng / L. The removal rates of tetracyclines, quinolones, sulfonamides, and macrolides were 85.4±0.6%, 90.1±0.2%, 84.3±0.5%, and 81.5±0.7%, respectively. The effluent concentrations of tetracycline, oxytetracycline, and ofloxacin were as low as 12.7±0.1 ng / L, 11.7±0.4 ng / L, and 2.2±0.3 ng / L, respectively. Furthermore, the effluent ammonia nitrogen was 0.8±0.1 mg / L, nitrate was 0.7±0.2 mg / L, phosphate was 0.2±0.1 mg / L, and COD was 23.6±0.7 mg / L, meeting the Class IV water quality standards for surface water in China.

[0053] This invention can be applied not only to the treatment of rural sewage but also to the treatment of effluent from urban sewage treatment plants. The functional parameters of the filter media layer, such as thickness and hydraulic retention time, can be flexibly adjusted according to the specific sewage quality testing results, adapting to local conditions. The burial depth of the prefabricated constructed wetland system can also be adjusted accordingly based on the actual terrain and geology.

[0054] (3) For maintenance, the main task is to regularly check its working condition. First, by monitoring the liquid level in different areas of the constructed wetland system, it is determined whether there is blockage. If the liquid level relationship does not conform to the following: inlet area I > upflow constructed wetland area II > buffer zone III ≥ downflow constructed wetland area IV > outlet area V, it indicates that there is blockage in the wetland. Backwash pump 2 can be used to alleviate the blockage. Second, by monitoring the concentration of antibiotics in the influent and effluent, it is determined that the antibiotics are removed by the absorption of wetland plants 17. If the antibiotic removal rate is significantly reduced, it indicates that the upper limit of the antibiotic accumulation capacity of wetland plants 17 has been reached. In this case, wetland plants 17 should be harvested and new wetland plant 17 seedlings should be planted.

[0055] In the upflow constructed wetland II, iron ore filter media releases iron ions, which, under the action of rhizosphere microorganisms, form an iron film with a thickness of 0.2-0.5 mm on the roots of wetland plants 17, enhancing the ability of the wetland plants 17 roots to absorb antibiotics, maintaining an antibiotic removal rate of over 85%. No chemical additives are required, reducing treatment costs by 80% compared to advanced oxidation methods, and there is no secondary pollution. In the downflow constructed wetland IV, under the oxygen secretion of the wetland plants 17 roots, an aerobic-anoxic-anaerobic wetland environment is formed from top to bottom, allowing nitrogen to be removed synergistically through nitrification, denitrification, and anaerobic ammonium oxidation. The sulfur / iron autotrophic denitrification coupled with anaerobic ammonium oxidation technology achieves zero addition of external carbon sources, avoiding the drawbacks of excessive nitrate production in a single anaerobic ammonium oxidation process, and the effluent quality can stably meet the Class IV water quality standards of Chinese surface water environment.

[0056] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the examples above. The present invention can reasonably select iron ore filter media and sulfide-based filter media with different particle sizes and iron contents, or plant different wetland plants 17 according to the application scenario, so as to achieve the purpose of purifying antibiotics and nitrogen and phosphorus pollutants in sewage.

Claims

1. A method for operating a sulfidogenic, enhanced-plant, antibiotic-accumulating, and denitrifying-deepening, assembled constructed wetland system, characterized in that, The assembled artificial wetland system comprises a shell, two backwashing pumps and a multi-parameter monitoring and control instrument for regulating the inflow and outflow of water, the shell is internally provided with, from left to right, a water inlet area, an upward-flow artificial wetland area, a buffer area, a downward-flow artificial wetland area and a water outlet area which are arranged in parallel and separated by partition walls, the liquid levels of the water inlet area, the upward-flow artificial wetland area, the downward-flow artificial wetland area and the water outlet area are successively lowered, the liquid level of the upward-flow artificial wetland area is higher than that of the buffer area, and the liquid level of the buffer area is not lower than that of the downward-flow artificial wetland area; The upward-flow artificial wetland area and the downward-flow artificial wetland area each comprise, from bottom to top, a supporting layer, a filler layer, a plant root layer and a emergent aquatic plant layer, the filler layer and the plant root layer of the upward-flow artificial wetland area are each filled with iron ore filter material, and the filler layer and the plant root layer of the downward-flow artificial wetland area are each filled with sulfur-iron-based filter material; The water inlet area comprises a water inlet pool, a water inlet port and a water inlet distribution pipe, the water inlet port is arranged at the lower part of the partition wall between the water inlet area and the upward-flow artificial wetland area, the inlet of the water inlet distribution pipe is connected with the water inlet port, the water inlet distribution pipe is arranged in the supporting layer of the upward-flow artificial wetland area, and a water inlet valve for controlling the opening and closing of the water inlet port is arranged at the water inlet port; The partition walls on the left and right sides of the buffer area are each provided with a through-wall pipe, the through-wall pipe arranged on the partition wall on the left side of the buffer area is arranged at the same level as the liquid level of the upward-flow artificial wetland area, and the through-wall pipe arranged on the partition wall on the right side of the buffer area is arranged at the same level as the liquid level of the downward-flow artificial wetland area; The water outlet area comprises a water outlet port, a water collection pool and a water outlet collection pipe, the water outlet port is arranged at the lower part of the partition wall between the downward-flow artificial wetland area and the water outlet area, the outlet of the water outlet collection pipe is connected with the water outlet port, the water outlet collection pipe is arranged in the supporting layer of the downward-flow artificial wetland area, and a water outlet valve for controlling the opening and closing of the water outlet port is arranged at the water outlet port; The two backwashing pumps are respectively connected with the inlet of the water inlet distribution pipe and the outlet of the water outlet collection pipe; The water inlet area, the buffer area and the water outlet area are each provided with a liquid level sensor for real-time monitoring of the liquid level, and the upward-flow artificial wetland area and the downward-flow artificial wetland area are each provided with a temperature / dissolved oxygen monitor for real-time monitoring of the temperature and dissolved oxygen, and the liquid level sensor, the temperature / dissolved oxygen monitor, the water inlet valve and the water outlet valve are all connected with the multi-parameter monitoring and control instrument; The operation method comprises three steps of starting, running and maintaining; S1, for the starting process, the residual sludge of a sewage treatment plant is used as seed sludge, the sludge concentration of the upward-flow artificial wetland area and the downward-flow artificial wetland area is controlled to be 1000-1500 mg / L, the diluted seed sludge is pumped into the upward-flow artificial wetland area and the downward-flow artificial wetland area through the water inlet distribution pipe and the water outlet collection pipe by the backwashing pumps, and the liquid surface covers the roots of the wetland plants, so as to start the artificial wetland system; S2, for the running process, the following steps are included: S21, sewage is used as the influent of the constructed wetland system, and the sewage is stored in the influent area; when the liquid level height of the influent area is greater than that of the upward-flow constructed wetland area, the influent valve is opened by the multi-parameter monitoring and control instrument to make the sewage evenly flow into the upward-flow constructed wetland area to remove the antibiotics in the sewage; S22, the sewage flows into the buffer area through the wall pipe on the left side of the buffer area and is stored; when the liquid level of the buffer area is higher than that of the wall pipe on the right side of the buffer area, the water quality uniform sewage flows into the downward-flow constructed wetland area through the wall pipe on the right side of the buffer area; S23, the sewage flows through the plant root layer, the filler layer and the supporting layer of the downward-flow constructed wetland area in sequence from top to bottom; under the action of oxygen secretion of the wetland plant roots, the sewage gradually transits from an aerobic environment to an anaerobic or anoxic environment, so that nitrification, denitrification and anaerobic ammonia oxidation occur simultaneously in the wetland; the phosphorus in the sewage is removed by absorption, assimilation and sedimentation of the wetland plants; S24, the treated sewage is collected by the effluent collecting pipe, flows into the water collecting tank through the effluent port, and the effluent water quality meets the requirements of the Chinese surface water environmental IV-class water quality standard; S3, for the maintenance process: one is to judge whether it is blocked by monitoring the liquid level height in different areas of the constructed wetland system, and the other is to judge the removal rate of the antibiotics absorbed by the wetland plants by monitoring the concentration of the antibiotics in the influent and effluent.

2. The operation method of the sulfide iron cycle enhanced constructed wetland system for antibiotic and deep denitrification of plant enrichment according to claim 1, characterized in that, The thicknesses of the filler layer and the plant root layer of the upward-flow constructed wetland area are 70-100 cm and 30-40 cm respectively, and both are filled with iron ore filter material prepared from iron tailings with a particle size of 5-10 mm, and the main components are zero-valent iron, Fe2O3 and Fe3O4; The thicknesses of the filler layer and the plant root layer of the downward-flow constructed wetland area are 70-100 cm and 30-40 cm respectively, and both are filled with sulfur-iron-based filter material prepared from sulfur solid waste and iron tailings with a particle size of 5-10 mm, and the main components are elemental sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4.

3. The operation method of the sulfide iron cycle enhanced constructed wetland system for antibiotic and deep denitrification of plant enrichment according to claim 1, characterized in that, The outer surface of the partition plate is provided with a geotextile waterproof layer.

4. The operation method of the sulfide iron cycle enhanced constructed wetland system for antibiotic and deep denitrification of plant enrichment according to claim 1, characterized in that, The thicknesses of the supporting layers of the upward-flow constructed wetland area and the downward-flow constructed wetland area are both 20 cm, and both are filled with gravel with a particle size of 20-40 mm.

5. The operation method of the sulfide iron cycle enhanced constructed wetland system for antibiotic and deep denitrification of plant enrichment according to claim 1, characterized in that, The emergent aquatic plant layer of the upward-flow constructed wetland area and the downward-flow constructed wetland area is planted with wetland plants with strong root system, strong oxygen secretion capacity and good stress resistance, including but not limited to Acorus gramineus, Phragmites australis and Arundo donax.

6. The operation method of the sulfide iron cycle enhanced constructed wetland system for antibiotic and deep denitrification of plant enrichment according to claim 1, characterized in that, The influent distribution pipe and the effluent collecting pipe both include a main pipe and a plurality of branch pipes, the branch pipes are uniformly distributed on both sides of the main pipe, the branch pipes on the same side are arranged in parallel, and a plurality of inlet and outlet holes are arranged on the main pipe and the branch pipes along the respective axial directions.

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