Assembly type artificial wetland system for strengthening antibiotic enrichment and deep denitrification of plants through sulfur-iron circulation and operation method thereof

Abstract

The invention belongs to the technical field of rural sewage treatment, and particularly discloses an assembled artificial wetland system for strengthening antibiotic enrichment and deep denitrification of plants through sulfur-iron circulation and an operation method of the assembled artificial wetland system. The method is used for solving the problems of high cost, high carbon consumption and easy generation of secondary pollution in the existing advanced treatment technology of rural sewage containing antibiotics and nitrogen pollutants. The wetland system comprises a shell, a backwashing pump and a multi-parameter measurement and control instrument; 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 are sequentially arranged in the shell from left to right. According to the invention, on one hand, the sulfur-iron source is utilized to strengthen the antibiotic enrichment capability of the wetland plant root system, and the antibiotics in the sewage are absorbed into the wetland plant body; and on the other hand, sulfur iron is used as an electron donor for short-cut denitrification, and deep removal of ammonia nitrogen is realized through anaerobic ammonia oxidation, so that the effluent quality reaches the water quality standard of IV-type water in the Chinese surface water environment.

Description

Technical Field

[0001] The invention belongs to the technical field of rural sewage treatment, and in particular relates to an assembled artificial wetland system for enhancing plant enrichment of antibiotics and deep denitrification through ferrous sulfide circulation and an operation method thereof. Background Art

[0002] The main sources of rural sewage in my country are domestic sewage from farmers, agricultural production wastewater and aquaculture wastewater. Rural sewage contains a large amount of nitrogen-containing pollutants and antibiotic residues. Antibiotics are an emerging micropollutant that is widely present in various environmental media. Due to the lack of sewage collection pipe networks and sewage treatment facilities in rural areas, as the amount of rural sewage discharge increases year by year, coupled with the irrational use of pesticides in rural areas, nitrogen-containing pollutants and antibiotics can enter the rural environment through various channels, threatening the rural ecological environment.

[0003] Antibiotics are highly ecotoxic and can promote the generation, transfer and spread of drug-resistant genes. On the one hand, they will harm the growth and reproduction of aquatic and terrestrial plants and animals and affect the entire food chain. On the other hand, they will cause bacteria and other microorganisms to gradually develop drug resistance, which has serious potential hazards to human health and the ecological environment. At the same time, long-term exposure to low-dose antibiotics in humans will cause allergic and poisoning reactions. Some antibiotics seriously interfere with various physiological functions of humans and have carcinogenic, teratogenic and mutagenic effects. At present, there are a variety of treatment technologies that can achieve the removal of antibiotics, such as adsorption, photodegradation and advanced oxidation. However, due to the disadvantages of such methods such as complex operation, high cost and easy secondary pollution, the promotion and application of these technologies are limited.

[0004] Excessive discharge of nitrogen-containing pollutants into natural water bodies will cause environmental problems such as eutrophication and black and smelly water bodies. Traditional denitrification processes require the consumption of a large amount of external carbon sources, have high operating costs and increase carbon emissions. Anaerobic ammonium oxidation has attracted widespread attention because it has the advantage of achieving deep denitrification without the addition of external carbon sources. Ammonia nitrogen and nitrite nitrogen can be synergistically removed under the action of anaerobic ammonium oxidizing bacteria (Anammox bacteria), but nitrates accounting for 11% of the total nitrogen removed will be produced, so the theoretical total nitrogen removal rate of anaerobic ammonium oxidation is only 89%. Sulfur-iron autotrophic denitrification uses reduced sulfur iron as an electron donor. In an anoxic environment, it can reduce the nitrate produced by anaerobic ammonium oxidation to nitrite, thereby providing a stable substrate for anaerobic ammonium oxidation, thereby improving the overall denitrification efficiency. If sulfur-iron autotrophic denitrification is coupled with anaerobic ammonium oxidation, it can replace the carbon source with a sulfur iron source to achieve low-carbon deep denitrification. Summary of the invention

[0005] One purpose of the present invention is to provide an assembled artificial wetland system for enhanced plant enrichment of antibiotics and deep denitrification by sulfur-iron circulation, which effectively solves the problems of high cost, high carbon consumption and easy secondary pollution in the existing deep treatment technology of rural sewage containing antibiotics and nitrogen-containing pollutants.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] An assembled artificial wetland system for enhanced plant enrichment of antibiotics and deep denitrification through sulfide-iron circulation comprises a shell, two backwash pumps and a multi-parameter measuring and controlling instrument for regulating the inlet and outlet water flow rates. The shell is provided with 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 boards from left to right. 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 decrease in sequence. 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.

[0008] The upward flow artificial wetland area and the downward flow artificial wetland area both include a supporting layer, a filler layer, a plant root layer and an emergent aquatic plant layer from bottom to top. The filler layer and the plant root layer of the upward flow artificial wetland area are both filled with iron ore filter material, and the filler layer and the plant root layer of the downward flow artificial wetland area are both filled with sulfide-based filter material.

[0009] The water inlet area includes a water inlet pool, a water inlet and a water inlet distribution pipe. The water inlet is arranged at the lower part of the partition board between the water inlet area and the upward flow artificial wetland area. The inlet of the water inlet distribution pipe is connected to the water inlet. The water inlet distribution pipe is arranged in the supporting layer of the upward flow artificial wetland area. The water inlet is provided with a water inlet valve for controlling the opening and closing of the water inlet.

[0010] Through-wall pipes are provided on the partition boards on the left and right sides of the buffer zone. The through-wall pipe on the left partition board of the buffer zone is set at the same level as the liquid level of the upward flow artificial wetland area, and the through-wall pipe on the right partition board of the buffer zone is set at the same level as the liquid level of the downward flow artificial wetland area.

[0011] The water outlet area includes a water outlet, a water collecting pool and a water outlet collecting pipe. The water outlet is arranged at the lower part of the partition board between the downward flow artificial wetland area and the water outlet area. The outlet of the water outlet collecting pipe is connected to the water outlet. The water outlet collecting pipe is arranged in the supporting layer of the downward flow artificial wetland area. The water outlet is provided with a water outlet valve for controlling the opening and closing of the water outlet.

[0012] Two backwash pumps are respectively connected to the inlet of the water inlet water distribution pipe and the outlet of the water outlet water collecting pipe.

[0013] The water inlet area, buffer area and water outlet area are all equipped with liquid level sensors for real-time monitoring of liquid levels. The upward flow artificial wetland area and the downward flow artificial wetland area are all equipped with temperature / dissolved oxygen monitors for real-time monitoring of temperature and dissolved oxygen. The liquid level sensor, temperature / dissolved oxygen monitor, water inlet valve and water outlet valve are all connected to a multi-parameter measurement and control instrument.

[0014] Furthermore, the thickness of the filler layer and the plant root layer in the upward flow artificial 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, 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 downward flow artificial wetland area are 70-100 cm and 30-40 cm respectively, and both are filled with sulfide-iron-based filter materials prepared from sulfur solid waste and iron tailings with a particle size of 5-10 mm, and the main components of which are elemental sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4.

[0016] Furthermore, a geotextile waterproof layer is provided on the outer surface of the partition board.

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

[0018] Furthermore, the emergent aquatic plant layers in the upward flow artificial wetland area and the downward flow artificial wetland area are planted with wetland plants with developed root systems, strong oxygen secretion capabilities and good stress resistance, including but not limited to yellow iris, reed and Phragmites australis.

[0019] Furthermore, the water inlet distribution pipe and the water outlet collection pipe both 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, and multiple water inlet and outlet holes are arranged on the main pipe and the branch pipes at equal intervals around the axis along their respective axes.

[0020] Another object of the present invention is to provide an operating method for the assembled artificial wetland system for enhanced plant enrichment of antibiotics and deep denitrification by sulfide-iron circulation as described in the above embodiments, which includes three steps: startup, operation and maintenance.

[0021] S1. For the startup process: use the residual sludge from the sewage treatment plant as seed sludge, control the sludge concentration in the upward flow artificial wetland area and the downward flow artificial wetland area at 1000-1500 mg / L, and use a backwash pump to pump the diluted seed sludge 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 respectively, until the liquid surface covers the roots of the wetland plants, so as to start the artificial wetland system.

[0022] S2. The operation process includes the following steps: S21. Using sewage as the inlet water of the artificial wetland system, the sewage is stored in the inlet area. When the liquid level in the inlet area is greater than the liquid level in the upward flow artificial wetland area, the inlet valve is controlled by a multi-parameter measurement and control instrument to open the water inlet, so that the sewage flows evenly into the upward flow artificial wetland area to remove antibiotics in the sewage.

[0023] S22. Sewage flows into the buffer zone through the through-the-wall pipe on the left side of the buffer zone for storage. When the liquid level in the buffer zone is higher than the through-the-wall pipe on the right side of the buffer zone, sewage with uniform water quality flows from the through-the-wall pipe on the right side of the buffer zone to the downward-flow artificial wetland area.

[0024] S23. The sewage flows from top to bottom through the plant root layer, filler layer and support layer of the downward flow artificial wetland area. Under the action of oxygen secretion by the roots of wetland plants, the sewage gradually transitions 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 precipitation by wetland plants.

[0025] S24. The treated sewage is collected by the outlet water collection pipe and flows into the water collection tank through the outlet. The effluent water quality meets the requirements of China's surface water environment Class IV water quality standards.

[0026] S3. For the maintenance process: First, the liquid level in different areas of the artificial wetland system is monitored to determine whether there is blockage; second, the removal rate of antibiotics absorbed by wetland plants is determined by monitoring the concentration of antibiotics in the inlet and outlet water.

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

[0028] (1) In the upward flow artificial wetland area of ​​the present invention, the iron ore filter material can release iron ions and form an iron film with a thickness of 0.2 to 0.5 mm on the roots of wetland plants under the action of rhizosphere microorganisms, thereby enhancing the ability of wetland plant roots to absorb antibiotics, and the antibiotic removal rate is maintained at more than 85%. No need to add chemicals, compared with the advanced oxidation method, the treatment cost is reduced by 80%, and there is no secondary pollution.

[0029] (2) In the downward flow artificial wetland area of ​​the present invention, under the action of oxygen secretion by the roots of wetland plants, an aerobic-anoxic-anaerobic wetland environment is formed from top to bottom, so that nitrogen is removed synergistically under the action of nitrification, denitrification and anaerobic ammonium oxidation. Sulfur / iron autotrophic denitrification coupled with anaerobic ammonium oxidation technology can achieve zero addition of external carbon source, avoid the disadvantage of excessive nitrate production by a single anaerobic ammonium oxidation process, and the effluent water quality can stably meet the water quality standard of Class IV water in China's surface water environment. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0033] List of reference numerals: shell-1; backwash pump-2; multi-parameter measuring and controlling instrument-3; partition board-4; water inlet pool-5; water inlet-6; water inlet distribution pipe-7; water outlet-8; water collecting pool-9; water outlet collecting pipe-10; main pipeline-11; branch pipeline-12; water inlet and outlet holes-13; through-wall pipe-14; liquid level sensor-15; temperature / dissolved oxygen monitor-16; wetland plants-17; water inlet area-I; upward flow artificial wetland area-II; buffer zone-III; downward flow artificial wetland area-IV; water outlet area-V; supporting layer-i; filler layer-ii; plant root layer-iii; emergent aquatic plant layer-iv. DETAILED DESCRIPTION

[0034] Example 1: An assembled artificial wetland system for enhancing plant enrichment of antibiotics and deep denitrification by ferrous sulfide circulation, such as Figure 1 and Figure 2 As shown, it includes a shell 1, two backwash pumps 2 and a multi-parameter measuring and controlling instrument 3 for regulating the inlet and outlet water flow. The shell 1 is composed of a stainless steel frame and a steel plate. From left to right, the shell 1 is provided with a water inlet area I, an upward flow artificial wetland area II, a buffer area III, a downward flow artificial wetland area IV and a water outlet area V, which are arranged in parallel and separated by a lightweight partition board 4. The liquid levels of the water inlet area I, the upward flow artificial wetland area II, the downward flow artificial wetland area IV and the water outlet area V decrease in sequence. The liquid level of the upward flow artificial wetland area II is higher than the liquid level of the buffer area III, and the liquid level of the buffer area III is not lower than the liquid level of the downward flow artificial wetland area IV. In this embodiment, the outer surface of the lightweight partition board 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 inlet distribution pipe 7. The water inlet 6 is arranged at the lower part of the lightweight partition board 4 between the water inlet area I and the upward flow artificial wetland area II. The inlet of the water inlet distribution pipe 7 is connected to the water inlet 6. The water inlet distribution pipe 7 is arranged on the supporting layer i of the upward flow artificial wetland area II. A water inlet valve for controlling the opening and closing of the water inlet 6 is provided at the water inlet 6.

[0036] The water outlet area V includes a water outlet 8, a water collecting pool 9 and a water outlet collecting pipe 10. The water outlet 8 is arranged at the lower part of the lightweight partition board 4 between the downward flow artificial wetland area IV and the water outlet area V. The outlet of the water outlet collecting pipe 10 is connected to the water outlet 8. The water outlet collecting pipe 10 is arranged on the supporting layer i of the downward flow artificial wetland area IV. The water outlet 8 is provided with a water outlet valve for controlling the opening and closing of the water outlet 8.

[0037] The two backwash pumps 2 are connected to the inlet of the water inlet distribution pipe 7 and the outlet of the water outlet collection pipe 10 respectively. Figure 3 As shown, the water inlet distribution pipe 7 and the water outlet collection pipe 10 both include a main pipe 11 and a plurality of branch pipes 12. The main pipe 11 is a PVC pipe with an inner diameter of 10 cm. Ten water inlet and outlet holes 13 with an aperture of 15 mm are arranged at equal intervals along the axial direction of the main pipe 11. 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. Eight water inlet and outlet holes 13 with an aperture of 10 mm are arranged at equal intervals along the axial direction of the branch pipes 12. The structural arrangement of the water inlet distribution pipe 7 and the water outlet collection pipe 10 is not only conducive to uniform water distribution and water collection, but also conducive to supplementing the matrix of the filler layer ii in the form of microparticles (particle size of about 100 microns) along the water flow.

[0038] The buffer zone III mainly plays a buffering role to achieve uniform water distribution. The lightweight partition boards 4 on the left and right sides of the buffer zone III are both provided with through-wall pipes 14. The through-wall pipe 14 on the partition board 4 on the left side of the buffer zone III is set at the same level as the liquid level of the upward flow artificial wetland area II, and the through-wall pipe 14 on the partition board 4 on the right side of the buffer zone III is set at the same level as the liquid level of the downward flow artificial wetland area IV. In this embodiment, the through-wall pipe 14 is a PVC pipe with an inner diameter of 15 cm.

[0039] The water inlet area I, buffer area III and water outlet area V are all provided with a liquid level sensor 15 for real-time monitoring of the liquid level, and the upward flow artificial wetland area II and the downward flow artificial wetland area IV are all provided with a temperature / dissolved oxygen monitor 16 for real-time monitoring of temperature and dissolved oxygen. The liquid level sensor 15, the temperature / dissolved oxygen monitor 16, the water inlet valve and the water outlet valve are all connected to the multi-parameter measurement and control instrument 3.

[0040] The upward flow artificial wetland area II and the downward flow artificial wetland area IV both include a support layer i, a filler layer ii, a plant root layer iii and an emergent aquatic plant layer iv from bottom to top. In this embodiment, the thickness of the filler layer ii and the plant root layer iii of the upward flow artificial wetland area II 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, the main components of which are zero-valent iron, Fe2O3 and Fe3O4, etc., and a small amount of CaCO3, etc., mainly for iron cycle enhancement plant enrichment of antibiotics. The thickness of the filler layer ii and the plant root layer iii in the downward flow artificial wetland area IV are 70-100 cm and 30-40 cm respectively. They are both filled with sulfur-iron based filter materials prepared from sulfur solid waste and iron tailings with a particle size of 5-10 mm. The main components are sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4, etc. The main purpose is to carry out sulfur-iron cycle to enhance sulfur / iron autotrophic denitrification coupled with anaerobic ammonia oxidation for deep nitrogen removal.

[0041] In this embodiment, the thickness of the supporting layer i in the upward flow artificial wetland area II and the downward flow artificial wetland area IV is 20 cm, and both are filled with gravel with a particle size of 20 to 40 mm. The emergent aquatic plant layer iv in the upward flow artificial wetland area II and the downward flow artificial wetland area IV is planted with wetland plants 17 with developed root systems, strong oxygen secretion capacity and good stress resistance, such as yellow calamus, reed and reed bamboo, etc., with a planting density of 25 plants / m 2 .

[0042] This embodiment is used to achieve deep denitrification of rural sewage and synergistic removal of antibiotic pollutants. Specifically, on the one hand, the ability of the roots of wetland plants 17 to enrich antibiotics is enhanced by using a sulfide iron source, and the antibiotics in the sewage are absorbed into the wetland plants 17, and finally the removal of antibiotics is achieved by harvesting the wetland plants 17; on the other hand, sulfide iron is used as an electron donor for short-range denitrification, and the generated nitrite is further deeply removed by anaerobic ammonia oxidation with ammonia nitrogen in the raw sewage. The operation method of the assembled artificial wetland system for enhancing the enrichment of antibiotics and deep denitrification of wetland plants 17 by sulfide iron circulation described in Example 1 is further described in detail through Example 2.

[0043] Example 2: A method for operating an assembled artificial wetland system for enhanced plant enrichment of antibiotics and deep denitrification by sulfide-iron circulation as described in Example 1, comprising three steps: startup, operation and maintenance.

[0044] (1) For the startup process: the residual sludge from the sewage treatment plant is used as seed sludge, and the sludge concentration in the upward flow artificial wetland area II and the downward flow artificial wetland area IV is controlled at 1000-1500 mg / L. The mixed activated sludge (i.e. the diluted seed sludge) is pumped into the upward flow artificial wetland area II and the downward flow artificial wetland area IV through the water inlet distribution pipe 7 and the water outlet collection pipe 10 by the backwash pump 2, respectively, until the wetland liquid surface covers the roots of the wetland plants 17, so as to start the artificial wetland system.

[0045] (2) The operation process includes the following steps: S21, using rural sewage as the inlet water of the artificial wetland system. 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 is 78.3±0.1~2044.3±52.8ng / L), etc., among which 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] The rural sewage is stored in the water inlet area I. When the liquid level of the water inlet area I is greater than the liquid level of the upward flow artificial wetland area II, the water inlet valve is controlled by the multi-parameter measurement and control instrument 3 to open the water inlet 6, so that the rural sewage can flow evenly into the upward flow artificial wetland area II to remove antibiotics in the rural sewage.

[0047] Antibiotics in rural sewage are removed through the following process: First, as the water level rises, sewage flows into the anoxic filler layer ii filled with iron ore filter media. Under the action of microorganisms, antibiotics (such as tetracycline, oxytetracycline and ofloxacin, etc.) are used as electron donors and iron oxides are used as electron acceptors to undergo redox reactions, which partially degrade the antibiotics. At the same time, high-valent iron ions are reduced to low-valent states, promoting the activity of related microorganisms such as dissimilatory metal-reducing bacteria; secondly, as the water level rises to the plant root layer iii, the dissolved oxygen content increases, and the reduced low-valent iron is further oxidized, resulting in 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, and bacteria use the iron film formed in the rhizosphere by the catalase secreted by the plants, as well as oxides such as iron hydroxide produced by the hydrolysis of iron ore filter media to promote the accumulation of antibiotics in the roots of wetland plants 17. After the antibiotics are enriched in the roots of wetland plants 17, most of them are transferred to other tissues of wetland plants 17 through diffusion and plant transpiration, and finally the antibiotics are removed by harvesting the wetland plants 17.

[0048] S22. The sewage flows into the buffer zone III through the through-the-wall pipe 14 located on the left side of the buffer zone III for storage. When the liquid level of the buffer zone III is higher than the through-the-wall pipe 14 located on the right side of the buffer zone III, the sewage with uniform water quality flows from the through-the-wall pipe 14 located on the right side of the buffer zone III to the downward flow artificial wetland area IV.

[0049] S23, the sewage flows from top to bottom through the plant root layer iii, filler layer ii and support layer i of the downward flow artificial wetland area IV. Under the action of plant root oxygen secretion, the sewage gradually transitions from the aerobic environment of the root system to the anaerobic or anoxic environment of the lower part of the wetland, so that nitrification, denitrification and anaerobic ammonia oxidation occur simultaneously in the wetland. In the plant root layer iii, sufficient dissolved oxygen provides a good growth and reproduction environment for ammonia oxidizing bacteria and nitrite oxidizing bacteria, converting ammonia nitrogen into nitrate; at the same time, part of the ammonia nitrogen in the sewage is absorbed by the developed root system of wetland plants 17, supplying the growth and development of wetland plants 17. Due to the consumption of dissolved oxygen, the filler layer ii filled with sulfur-iron based filter material mainly presents anaerobic and anoxic states. In the upper layer of filler layer ii, the nitrate in the sewage generates nitrite under the action of sulfur / iron autotrophic short-range denitrification, providing sufficient substrate for anaerobic ammonia oxidation; in the lower layer of filler layer ii, the generated nitrite and ammonia nitrogen in the sewage are synergistically removed under the action of anaerobic ammonia oxidizing bacteria. In addition, the organic matter remaining in the sewage and the organic matter secreted by the roots of wetland plants17 provide some electron donors, driving the heterotrophic denitrification.

[0050] Phosphorus in sewage is mainly removed by plant absorption, assimilation and precipitation. Part of the phosphate in sewage is absorbed and assimilated by plants in the root layer iii of wetland plants 17, accumulated in the plants, and then removed by harvesting wetland plants 17. In the filler layer ii, the phosphate in sewage can react with the Fe released by the ferrous sulfide-based filter material. 3+ The generated precipitate is removed.

[0051] S24. Finally, the treated sewage is collected by the outlet water collecting pipe 10 and flows into the water collecting tank 9 through the outlet 8.

[0052] Under the conditions of hydraulic retention time of 36h and continuous flow operation, the total concentration of antibiotics in the artificial wetland system was reduced to 65.7-408.9ng / L, and the removal rates of tetracycline, quinolone, sulfonamide and macrolide antibiotics 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±0.1ng / L, 11.7±0.4ng / L and 2.2±0.3ng / L; and the effluent ammonia nitrogen was 0.8±0.1mg / L, nitrate was 0.7±0.2mg / L, phosphate was 0.2±0.1mg / L, COD was 23.6±0.7mg / L, which met the water quality standards for Class IV surface water in China.

[0053] In addition to being applicable to the treatment of rural sewage, the present invention can also be applied to the treatment of effluent from urban sewage treatment plants. The thickness of the functional filter material of the packing layer, the hydraulic retention time and other parameters can be flexibly adjusted according to the specific sewage quality detection conditions and adapted to local conditions. The burial depth of the assembled artificial wetland system can also be adjusted accordingly according to the actual terrain and geology.

[0054] (3) For the maintenance process, the main work is to regularly check its working condition. First, by monitoring the liquid level height in different areas of the artificial wetland system to determine whether there is blockage. If the liquid level height relationship does not meet the inlet area I>upward flow artificial wetland area II>buffer zone III≥downward flow artificial wetland area IV>outlet area V, it means that blockage has occurred in the wetland, and the backwash pump 2 can be used to alleviate the blockage inside the wetland. Second, by monitoring the concentration of antibiotics in the inlet and outlet water, the removal rate of antibiotics absorbed by wetland plants 17 can be determined. If the antibiotic removal rate is significantly reduced, it means that the upper limit of the wetland plant 17's ability to enrich antibiotics has been reached, and the wetland plants 17 should be harvested and new wetland plant 17 seedlings should be planted.

[0055] In the upward flow artificial wetland area II of the present invention, the iron ore filter material can release iron ions, and under the action of rhizosphere microorganisms, an iron film with a thickness of 0.2 to 0.5 mm is formed on the roots of the wetland plants 17, thereby enhancing the ability of the roots of the wetland plants 17 to absorb antibiotics, and the antibiotic removal rate is maintained at more than 85%. No need to add agents, compared with the advanced oxidation method, the treatment cost is reduced by 80%, and there is no secondary pollution. In the downward flow artificial wetland area IV, under the action of oxygen secretion by the roots of the wetland plants 17, an aerobic-anoxic-anaerobic wetland environment is formed from top to bottom, so that nitrogen is synergistically removed under the action of nitrification, denitrification and anaerobic ammonia oxidation. The sulfur / iron autotrophic denitrification coupled anaerobic ammonia oxidation technology can achieve zero addition of external carbon source, avoid the disadvantage of excessive nitrate produced by a single anaerobic ammonia oxidation process, and the effluent water quality can stably meet the water quality standard of Class IV water in China's 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 above examples. The present invention can reasonably select iron ore filter materials and sulfide-based filter materials with different particle sizes and different 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. An assembled artificial wetland system for enhancing plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation, characterized in that: It comprises a shell, two backwash pumps and a multi-parameter measuring and controlling instrument for regulating the inlet and outlet water flow rates. The shell is provided with 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 boards from left to right. 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 decrease in sequence. The liquid level of the upward flow artificial wetland area is higher than the liquid level of the buffer area, and the liquid level of the buffer area is not lower than the liquid level of the downward flow artificial wetland area. The upward flow artificial wetland area and the downward flow artificial wetland area both include a supporting layer, a filler layer, a plant root layer and an emergent aquatic plant layer from bottom to top, the filler layer and the plant root layer of the upward flow artificial wetland area are both filled with iron ore filter material, and the filler layer and the plant root layer of the downward flow artificial wetland area are both filled with sulfide-based filter material; The water inlet area includes a water inlet pool, a water inlet and a water inlet distribution pipe, the water inlet is arranged at the lower part of the partition board between the water inlet area and the upward flow artificial wetland area, the inlet of the water inlet distribution pipe is connected to the water inlet, the water inlet distribution pipe is arranged at the supporting layer of the upward flow artificial wetland area, and the water inlet is provided with a water inlet valve for controlling the opening and closing of the water inlet; The partition boards on the left and right sides of the buffer zone are both provided with through-wall pipes. The through-wall pipe on the left partition board of the buffer zone is set at the same level as the liquid level of the upward-flowing artificial wetland area, and the through-wall pipe on the right partition board of the buffer zone is set at the same level as the liquid level of the downward-flowing artificial wetland area. The water outlet area includes a water outlet, a water collecting pool and a water outlet collecting pipe, the water outlet is arranged at the lower part of the partition board between the downward flow artificial wetland area and the water outlet area, the outlet of the water outlet collecting pipe is connected to the water outlet, the water outlet collecting pipe is arranged at the supporting layer of the downward flow artificial wetland area, and the water outlet is provided with a water outlet valve for controlling the opening and closing of the water outlet; The two backwash pumps are respectively connected to the inlet of the water inlet distribution pipe and the outlet of the water outlet collection pipe; The water inlet area, buffer area and water outlet area are all equipped with liquid level sensors for real-time monitoring of liquid levels. The upward flow artificial wetland area and the downward flow artificial wetland area are all equipped with temperature / dissolved oxygen monitors for real-time monitoring of temperature and dissolved oxygen. The liquid level sensor, temperature / dissolved oxygen monitor, water inlet valve and water outlet valve are all connected to a multi-parameter measurement and control instrument.

2. The assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to claim 1, characterized in that: The thickness of the filler layer and the plant root layer in the upward flow artificial 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, the main components of which are zero-valent iron, Fe2O3 and Fe3O4; The thickness of the filler layer and the plant root layer in the downward flow artificial wetland area are 70-100 cm and 30-40 cm respectively, and both are filled with sulfide-iron-based filter materials prepared from sulfur solid waste and iron tailings with a particle size of 5-10 mm, and the main components of which are elemental sulfur, zero-valent iron, FeS, Fe2O3 and Fe3O4.

3. The assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to claim 2 is characterized in that: The outer surface of the partition board is provided with a geotextile waterproof layer.

4. The assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to claim 3 is characterized in that: The thickness of the supporting layer of the upward flow artificial wetland area and the downward flow artificial wetland area is 20 cm, and both are filled with gravel with a particle size of 20 to 40 mm.

5. The assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to claim 4 is characterized in that: The emergent aquatic plant layers in the upward flow artificial wetland area and the downward flow artificial wetland area are planted with wetland plants with developed root systems, strong oxygen secretion capabilities and good stress resistance, including but not limited to yellow iris, reed and Phragmites australis.

6. The assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to claim 5, characterized in that: The water inlet distribution pipe and the water outlet collection pipe both include a main pipeline and multiple branch pipelines. The branch pipelines are evenly distributed on both sides of the main pipeline, and the branch pipelines on the same side are arranged in parallel. The main pipeline and the branch pipeline are both provided with multiple water inlet and outlet holes at equal intervals around the axis along their respective axes.

7. An operating method of an assembled artificial wetland system for strengthening plant enrichment of antibiotics and deep denitrification by ferrous sulfur circulation according to any one of claims 1 to 6, characterized in that: It includes three steps: startup, operation and maintenance; S1. For the startup process: the excess sludge from the sewage treatment plant is used as seed sludge, the sludge concentration in the upward and downward artificial wetland areas is controlled at 1000-1500 mg / L, and the diluted seed sludge is pumped into the upward and downward artificial wetland areas through the inlet water distribution pipe and the outlet water collection pipe respectively by a backwash pump until the liquid surface covers the roots of the wetland plants, so as to start the artificial wetland system; S2. The operation process includes the following steps: S21. Use sewage as the inlet of the artificial wetland system and store the sewage in the inlet area. When the liquid level in the inlet area is higher than the liquid level in the upward-flowing artificial wetland area, control the inlet valve through a multi-parameter measuring and controlling instrument to open the inlet, so that the sewage flows evenly into the upward-flowing artificial wetland area to remove antibiotics in the sewage. S22. Sewage flows into the buffer zone through the through-wall pipe on the left side of the buffer zone for storage. When the liquid level in the buffer zone is higher than the through-wall pipe on the right side of the buffer zone, the sewage with uniform water quality flows from the through-wall pipe on the right side of the buffer zone to the downward flow artificial wetland area. S23. Sewage flows from top to bottom through the plant root layer, filler layer and support layer in the downward flow artificial wetland area. Under the action of oxygen secretion by the roots of wetland plants, the sewage gradually transitions from an aerobic environment to an anaerobic or anoxic environment, so that nitrification, denitrification and anaerobic ammonium oxidation occur simultaneously in the wetland; phosphorus in sewage is removed by absorption, assimilation and precipitation of wetland plants; S24. The treated sewage is collected by the effluent collection pipe and flows into the collection tank through the outlet. The effluent water quality meets the requirements of China's surface water environment Class IV water quality standards; S3. For the maintenance process: First, the liquid level in different areas of the artificial wetland system is monitored to determine whether there is blockage; second, the removal rate of antibiotics absorbed by wetland plants is determined by monitoring the concentration of antibiotics in the inlet and outlet water.

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