Constructed wetland construction method for lifting tail water of urban domestic sewage treatment plant

Abstract

The invention discloses a constructed wetland construction method for tail water lifting of an urban domestic sewage treatment plant, and particularly relates to the technical field of sewage treatment, and the constructed wetland construction method comprises the following steps: S1, landform reconstruction and diversion system construction; s2, layered construction of the composite anti-seepage structure; s3, precise configuration of gradient plants; s4, constructing an anti-impact hydraulic system; s5, establishing an ecological cooperation system; and S6, implementing a dynamic operation and maintenance mechanism. Uniform distribution of water flow is achieved through optimization of a flow guide structure, long-acting anti-seepage is guaranteed through a composite anti-seepage layer, gradient plant communities construct a three-dimensional purification network, the pollutant removal efficiency is remarkably improved, an anti-impact system is integrated with an intelligent regulation and control module, water quantity fluctuation of 30% or above can be rapidly responded, and the water quality is improved. The three-level ecological cooperation system realizes pollution interception-deep purification-ecological restoration whole process control, and the intelligent operation and maintenance system improves the management precision by three times and reduces the operation cost by more than 40% through a real-time monitoring and prediction model.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method for constructing an artificial wetland for lifting tail water of a town sewage treatment plant. Background Art

[0002] As an important ecological means to improve the quality of tailwater from urban sewage treatment plants, artificial wetland technology has been widely used in engineering practice in recent years. Traditional construction methods mostly use single-structure wetlands to remove pollutants through matrix adsorption, plant absorption and microbial decomposition, but they have exposed significant defects in actual operation. In existing technologies, diversion systems often use straight ditches or simple cofferdams, resulting in uneven water distribution, short-circuit rates as high as 30%-40%, and effective reaction area utilization rates of less than 65%; anti-seepage structures mostly rely on single-layer geomembranes or clay, which are prone to leakage due to root penetration or foundation settlement during long-term operation, and the leakage volume generally exceeds 2m 3 / d, posing a risk of groundwater contamination. Furthermore, the plant configuration is limited to single species such as reeds and cattails, resulting in significant seasonal fluctuations in biomass. The purification efficiency varies by over 60% between summer and winter, and the synergistic removal efficiency of nitrogen and phosphorus has long stagnated at 50%-60%.

[0003] Existing technologies also have significant shortcomings in hydraulic regulation and operation and maintenance management. Most systems rely on manual valves to adjust water flow, resulting in emergency response times exceeding one hour, making them unable to cope with instantaneous water volume fluctuations (>20% of design flow). Substrate blockage monitoring relies on monthly manual sampling, and repair costs account for over 35% of operating expenses. These technical deficiencies have severely restricted the large-scale application of constructed wetlands. Pollutant penetration rates exceed 30% during rainstorms, and TN removal rates are less than 50% at low temperatures in winter, making it difficult to meet the Level A requirements of the "Pollutant Discharge Standards for Urban Wastewater Treatment Plants." Furthermore, extensive operation and maintenance lead to high energy consumption, which conflicts with the energy conservation and consumption reduction needs of the "dual carbon" goals. The prominent problem of single ecological functions and the lack of a biodiversity support system limit their value extension in the field of ecological restoration. These systemic bottlenecks have given rise to an urgent need for new construction methods with precise parameter control, intelligent regulation, and multi-stage coordinated purification capabilities. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for constructing an artificial wetland for lifting tailwater from urban domestic sewage treatment plants, which can effectively solve the problems in the above-mentioned background technology.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant comprises the following steps:

[0007] S1. Terrain modification and diversion system construction: The original depression was used to create a water level drop of 0.3-0.6m. A combined diversion system was formed by setting up folded plate cofferdams with a spacing of 1.2m and 0.8m wide transverse deep trenches to stabilize the water flow velocity at 0.05-0.08m / s.

[0008] S2. Layered construction of composite anti-seepage structure: using 0.3m thick HDPE geomembrane and 0.6m compacted clay composite layer (compaction degree 93%-95%), with 3-5cm graded cobblestone cover layer, to form a permeability coefficient ≤1×10 -6 cm / s three-dimensional anti-seepage system;

[0009] S3. Gradient plant precise configuration: 36 plants / m are configured according to the water depth gradient of 0-0.4m, 0.4-1m and 1-2m. 2 Emergent plants, 49 plants / m 2 Reeds and 18 plants / m 2 Submerged plants form a three-layer purification zone;

[0010] S4. Construction of shock-resistant hydraulic system: A plum blossom-shaped water inlet system with a 1% opening ratio is set up, equipped with a DN800 overrun pipe (slope 2.5%) and a 0.05MPa differential pressure on-off valve to achieve 20% overload emergency diversion;

[0011] S5. Establishment of ecological synergy system: Construction of 3350m hedge belt (3 shrubs / m) - 17500m 2 Buffer zone (25 plants / m 2 Aquatic plants) - artificial wetland three-stage purification system, hydraulic retention time ratio of 6:15:9;

[0012] S6. Implementation of dynamic operation and maintenance mechanism: adopt three-point sampling to monitor the substrate permeability coefficient every month, combined with double harvest in March / October (leaving 5-8cm stubble) and 8mg / L ammonia nitrogen concentration early warning mechanism.

[0013] Preferably, the diversion system in S1 consists of folded plate cofferdams with a spacing of 1.2m and transverse deep trenches with a width of 0.8m. The height of the folded plate is 1 / 2 of the water depth of the treatment area, and a gravel layer with a particle size of 5cm is laid at the bottom of the deep trench.

[0014] Preferably, the composite anti-seepage structure in step S2 comprises three layers: upper, middle and lower layers, wherein:

[0015] The lower layer is a composite layer of 1.2mm thick high-density polyethylene geomembrane and 0.6m thick clay. The geomembrane seams are double-welded, and the clay layer is compacted three times to a compaction degree of 93%-95%;

[0016] The middle layer is a 0.4 m thick clay-humus mixed layer (7:3 volume ratio, organic matter content 3.5%-4.2%);

[0017] The upper layer is a 3 cm thick cobblestone covering layer (5-8 cm:3-5 cm=2:1 mass ratio), and a nylon anti-sinking net with a pore size of 2 mm is laid underneath.

[0018] Preferably, the plant configuration in step S3 is specifically as follows:

[0019] 0-0.4m shallow water area: 36 plants each of windmill grass, iris, and lily of the valley / m 2 Planting is staggered in a checkerboard pattern;

[0020] 0.4-1m transition zone: 49 reeds / m 2 Forming a continuous strip distribution;

[0021] 1-2m deep water area: Vallisneria and Hydrilla are planted at a density ratio of 2:1, with a total density of 18 plants / m 2 .

[0022] Preferably, the hydraulic system in step S4 comprises:

[0023] Water inlet unit: The perforated pipe has an opening diameter of 8mm, a hole spacing of 12cm, and is arranged in a plum blossom shape;

[0024] Water outlet unit: The adjustable elbow is equipped with a 30cm diameter HDPE one-way valve, and the opening and closing pressure difference is set to 0.05MPa;

[0025] Emergency unit: The diameter of the overflow pipe is DN800 and the slope is set to 2.5%.

[0026] Preferably, the ecological synergy system in step S5 includes:

[0027] Hedgerow isolation belt: Photinia fraseri and Pittosporum tobira are planted in a ratio of 2:1, with a spacing of 0.3m between plants;

[0028] Ecological buffer zone: The width of the emergent plant belt is 8m, with 25 reeds and 25 cattails per m 2 ;

[0029] The third-level purification area: hydraulic retention time is controlled at 6h, 15h and 9h respectively.

[0030] Preferably, the dynamic operation and maintenance in step S6 includes:

[0031] Substrate monitoring: Take three column samples with a depth of 0.5m at the water inlet, treatment area and outlet every month;

[0032] Plant harvesting: Above-ground parts harvested from March 20-25, underground rhizomes dredged from October 10-15;

[0033] Emergency control: When the influent NH3-N concentration exceeds 8mg / L, start the standby aeration unit and add 5g / m 3 nitrifying bacteria.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention achieves uniform water distribution through optimized diversion structure, a composite anti-seepage layer ensures long-term leakage prevention, and a gradient plant community constructs a three-dimensional purification network, significantly improving pollutant removal efficiency. The impact-resistant system integrates an intelligent control module, which can quickly respond to water volume fluctuations of more than 30% and ensure stable operation under extreme working conditions. The three-level ecological synergy system realizes full-process control of pollution interception, deep purification, and ecological restoration. The intelligent operation and maintenance system improves management accuracy by 3 times and reduces operating costs by more than 40% through real-time monitoring and prediction models.

[0036] 2. The present invention provides habitats for aquatic organisms through diversified plant communities, hedge buffer zones reduce non-point source pollution by more than 60%, biomass resource utilization avoids secondary pollution, zero chemical additions throughout the entire process ensure environmental safety, and the effluent water quality is stable and meets the surface water Class IV standard. The system is climate adaptable, maintains 85% purification efficiency in winter, and has a treatment capacity during heavy rains that is twice that of conventional processes. It provides urban sewage treatment plants with an economical and efficient ecological improvement plan that combines environmental benefits with promotional value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0038] Figure 2 It is a schematic diagram of the composite anti-seepage structure process of the present invention;

[0039] Figure 3 It is a schematic diagram of the hydraulic system flow of the present invention. DETAILED DESCRIPTION

[0040] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0041] like Figure 1-3 As shown, the method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant comprises the following steps:

[0042] S1. Terrain modification and diversion system construction: The original depression was used to create a water level drop of 0.3-0.6m. A combined diversion system was formed by setting up folded plate cofferdams with a spacing of 1.2m and 0.8m wide transverse deep trenches to stabilize the water flow velocity at 0.05-0.08m / s.

[0043] Specifically, the original depression was used to reshape the terrain to form a three-level terraced terrain with a water level drop of 0.3m-0.6m. A folded plate cofferdam with a spacing of 1.2m±0.1m, a height of 0.5m, and an inclination angle of 55° was set up, combined with a transverse deep ditch with a width of 0.8m±0.05m. A 5cm thick gravel layer (particle size 3-5cm) was laid at the bottom of the deep ditch to form a combined diversion system. The diversion system stabilizes the water flow velocity at 0.05-0.08m / s and the turbulence coefficient is ≤0.15.

[0044] S2. Layered construction of composite anti-seepage structure: 1.2mm thick HDPE geomembrane and 0.6m compacted clay composite layer (compaction degree 93%-95%), with 3-5cm graded cobblestone cover layer, to form a permeability coefficient ≤1×10 -6 cm / s three-dimensional anti-seepage system;

[0045] Specifically, the lower layer uses a 1.2mm thick HDPE geomembrane (breaking strength ≥ 25kN / m) and a 0.6m compacted clay layer for composite anti-seepage, the middle layer is a clay-humus mixed layer (7:3 volume ratio, CEC ≥ 25cmol / kg), and the upper layer is paved with 3-5cm pebbles (5-8cm:3-5cm = 2:1 mass ratio), with 6-8 air holes (2cm in diameter) set per square meter.

[0046] S3. Gradient plant precise configuration: 36 plants / m are configured according to the water depth gradient of 0-0.4m, 0.4-1m and 1-2m. 2 Emergent plants, 49 plants / m 2 Reeds and 18 plants / m 2 Submerged plants form a three-layer purification zone;

[0047] S4. Construction of shock-resistant hydraulic system: A plum blossom-shaped water inlet system with a 1% opening ratio is set up, equipped with a DN800 overrun pipe (slope 2.5%) and a 0.05MPa differential pressure on-off valve to achieve 20% overload emergency diversion;

[0048] S5. Establishment of ecological synergy system: Construction of 3350m hedge belt (3 shrubs / m) - 17500m 2 Buffer zone (25 plants / m 2 Aquatic plants) - artificial wetland three-stage purification system, hydraulic retention time ratio of 6:15:9;

[0049] Hedge belt: Build a 3350m double-row hedge, with 2 red-leaf photinia plants / m in the front row and 1 pittosporum plant / m in the back row.

[0050] Buffer zone: 17500m 2 Emergent plant belt (25 plants each of reed and cattail / m 2 , inter-row intercropping).

[0051] Hydraulic connection of the three-level system: hedge belt (HRT6h) → artificial wetland (HRT15h) → buffer belt (HRT9h), set up online flow meter (accuracy ±2%), and realize hydraulic load 0.3-0.5m 3 / (m 2 ·d).

[0052] S6. Implementation of dynamic operation and maintenance mechanism: adopt three-point sampling to monitor the substrate permeability coefficient every month, combined with double harvest in March / October (leaving 5-8cm stubble) and 8mg / L ammonia nitrogen concentration early warning mechanism.

[0053] Substrate monitoring: Columnar samples (5 cm in diameter, 50 cm in depth) were collected at the inlet (0-0.5 m depth), the middle of the treatment area (0.3-0.8 m depth), and the outlet (0-0.3 m depth) on the 5th, 15th, and 25th of each month, respectively.

[0054] Plant management: When harvesting the above-ground parts from March 20 to 25, leave 5cm±1cm of stubble. When dredging the underground rhizomes from October 10 to 15, remove 40%±5%.

[0055] The diversion system in S1 consists of folded plate cofferdams with a spacing of 1.2m and a transverse deep ditch with a width of 0.8m. The height of the folded plate is 1 / 2 of the water depth of the treatment area, and a gravel layer with a particle size of 5cm is laid at the bottom of the deep ditch.

[0056] Furthermore, the diversion system forms a multi-level energy dissipation structure through a combination of 304 stainless steel folded plate cofferdams (thickness 1.5mm, surface galvanized) with a spacing of 1.2m and a 0.8m wide transverse deep ditch, combined with a 5cm thick gravel layer (with a particle size of 3-5cm accounting for more than 85%) laid at the bottom of the deep ditch.

[0057] This design controls the water flow Reynolds number within the range of 800-1200, effectively eliminating the eddy current phenomenon. Actual measurements have shown that the incidence of short-circuiting can be reduced from 35% in traditional processes to below 8%. The 55° inclination angle design of the folded plate has been optimized through fluid mechanics simulation, allowing the water flow to produce alternating laminar and turbulent motion at a flow rate of 0.05-0.08m / s, promoting a 42% increase in oxygen mass transfer efficiency. At the same time, the built-in ultrasonic flow sensor (sampling frequency 10Hz) can provide real-time feedback on the flow rate distribution and automatically adjust the opening of the water inlet valve to ensure that the hydraulic load deviation of each treatment unit is ≤±5%.

[0058] The composite anti-seepage structure in step S2 includes three layers: upper, middle and lower layers, wherein:

[0059] The lower layer is a composite layer of 1.2mm thick high-density polyethylene geomembrane and 0.6m thick clay. The geomembrane seams are double-welded, and the clay layer is compacted three times to a compaction degree of 93%-95%;

[0060] The middle layer is a 0.4 m thick clay-humus mixed layer (7:3 volume ratio, organic matter content 3.5%-4.2%);

[0061] The upper layer is a 3 cm thick cobblestone covering layer (5-8 cm:3-5 cm=2:1 mass ratio), and a nylon anti-sinking net with a pore size of 2 mm is laid underneath.

[0062] The composite anti-seepage layer is constructed using a double-weld process (weld width 10mm, air pressure detection value 0.15-0.20MPa), and the clay layer is compacted three times (compaction energy of each layer ≥30kJ / m 3 ), spray 2% lime water (dosage 0.5L / m 2 ) to form an anti-scouring surface. A polyester anti-sinking net with a pore size of 2 mm (breaking strength ≥ 50 kN / m) was laid under the cobblestone layer. After 500 freeze-thaw cycle tests, the permeability coefficient remained ≤ 1.0 × 10 -6 cm / s, and the service life is extended to more than 15 years.

[0063] The plant configuration in step S3 is as follows:

[0064] 0-0.4m shallow water area: 36 plants of windmill grass, iris and lily of the valley are planted in a checkerboard pattern;

[0065] 0.4-1m transition zone: 49 reeds / m2 form a continuous strip distribution;

[0066] 1-2m deep water area: Vallisneria and Hydrilla are planted at a density ratio of 2:1, with a total density of 18 plants / m 2 .

[0067] Furthermore, the emergent plant belt adopts a planting layout of 15° from north to south and east, with windmill grass and iris arranged alternately with a plant spacing of 15cm×15cm, and the reed strips are at an angle of 30° to the water flow direction.

[0068] An online transparency monitor (range 0-5m, accuracy ±0.1m) is installed in the submerged plant area. When the water depth / transparency value is ≥1.8, the supplementary lighting system (light intensity ≥5000lux) is automatically activated to ensure that the photosynthetic efficiency of submerged plants is ≥85%.

[0069] The hydraulic system in step S4 includes:

[0070] Water inlet unit: The perforated pipe has an opening diameter of 8mm, a hole spacing of 12cm, and is arranged in a plum blossom shape;

[0071] Water outlet unit: The adjustable elbow is equipped with a 30cm diameter HDPE one-way valve, and the opening and closing pressure difference is set to 0.05MPa;

[0072] Emergency unit: The diameter of the overflow pipe is DN800 and the slope is set to 2.5%.

[0073] Furthermore, the water inlet perforated pipe is made of UPVC (ring stiffness ≥ 8kN / m 2 The orifice is chamfered (45° angle, 0.5mm depth) to prevent clogging. The bypass pipe is equipped with a quick-connect flange (PN 1.0MPa) and a pneumatic actuator (response time ≤ 5s). This allows for emergency diversion of 30% of the water flow within 15 minutes during heavy rain events, and the system's shock load resistance is 1.8 times the design value.

[0074] The ecological synergy system in step S5 includes:

[0075] Hedgerow isolation belt: Photinia fraseri and Pittosporum tobira are planted in a ratio of 2:1, with a spacing of 0.3m between plants;

[0076] Ecological buffer zone: The width of the emergent plant belt is 8m, with 25 reeds and 25 cattails per m 2 ;

[0077] The third-level purification area: hydraulic retention time is controlled at 6h, 15h and 9h respectively.

[0078] The hedge belt is planted in double rows (0.3m spacing in the front row and 0.5m in the back row) and equipped with a drip irrigation system (flow rate 2L / h per plant). The buffer zone is equipped with an adjustable overflow weir (adjustment accuracy ±2cm), and the water level is controlled to stabilize the oxygen secretion of the roots of the emergent plants at 0.8-1.2gO2 / m 2 ·d, promote the abundance of nitrifying bacteria to 10 6 -10 7 CFU / g, and the ammonia nitrogen conversion efficiency is increased by more than 40%.

[0079] The dynamic operation and maintenance in step S6 includes:

[0080] Substrate monitoring: Take three column samples with a depth of 0.5m at the water inlet, treatment area and outlet every month;

[0081] Plant harvesting: Above-ground parts harvested from March 20-25, underground rhizomes dredged from October 10-15;

[0082] Emergency control: When the influent NH3-N concentration exceeds 8mg / L, start the standby aeration unit and add 5g / m 3 nitrifying bacteria.

[0083] Substrate monitoring utilizes a custom sampler (5cm inner diameter, 50cm length), with a sampling depth error of ≤±1cm. Root dredging utilizes a combination of high-pressure water jets (2-3MPa) and vacuum extraction, achieving a removal efficiency of ≥90% and a root damage rate of ≤5%. An intelligent control system, leveraging a machine learning model (with a prediction accuracy of ≥92%), provides 12 hours of advance warning of water quality fluctuations, automatically adjusting hydraulic load (±20%) and aeration intensity (DO controlled at 4-5mg / L).

[0084] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant, comprising the following steps: S1. Terrain modification and diversion system construction: The original depression was used to create a water level drop of 0.3-0.6m. A combined diversion system was formed by setting up folded plate cofferdams with a spacing of 1.2m and 0.8m wide transverse deep trenches to stabilize the water flow velocity at 0.05-0.08m / s. S2. Layered construction of composite anti-seepage structure: using 0.3m thick HDPE geomembrane and 0.6m compacted clay composite layer (compaction degree 93%-95%), with 3-5cm graded cobblestone cover layer, to form a permeability coefficient ≤1×10 -6 cm / s three-dimensional anti-seepage system; S3. Gradient plant precise configuration: 36 plants / m are configured according to the water depth gradient of 0-0.4m, 0.4-1m and 1-2m. 2 Emergent plants, 49 plants / m 2 Reeds and 18 plants / m 2 Submerged plants form a three-layer purification zone; S4. Construction of shock-resistant hydraulic system: A plum blossom-shaped water inlet system with a 1% opening ratio is set up, equipped with a DN800 overrun pipe (slope 2.5%) and a 0.05MPa differential pressure on-off valve to achieve 20% overload emergency diversion; S5. Establishment of ecological synergy system: Construction of 3350m hedge belt (3 shrubs / m) - 17500m 2 Buffer zone (25 plants / m 2 Aquatic plants) - artificial wetland three-stage purification system, hydraulic retention time ratio of 6:15:9; S6. Implementation of dynamic operation and maintenance mechanism: adopt three-point sampling to monitor the substrate permeability coefficient every month, combined with double harvest in March / October (leaving 5-8cm stubble) and 8mg / L ammonia nitrogen concentration early warning mechanism.

2. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The diversion system in S1 consists of folded plate cofferdams with a spacing of 1.2m and a transverse deep ditch with a width of 0.8m. The height of the folded plate is 1 / 2 of the water depth of the treatment area, and a gravel layer with a particle size of 5cm is laid at the bottom of the deep ditch.

3. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The composite anti-seepage structure in step S2 comprises three layers: upper, middle and lower layers, wherein: The lower layer is a composite layer of 1.2mm thick high-density polyethylene geomembrane and 0.6m thick clay. The geomembrane seams are double-welded, and the clay layer is compacted three times to a compaction degree of 93%-95%; The middle layer is a 0.4 m thick clay-humus mixed layer (7:3 volume ratio, organic matter content 3.5%-4.2%); The upper layer is a 3 cm thick cobblestone covering layer (5-8 cm:3-5 cm=2:1 mass ratio), and a nylon anti-sinking net with a pore size of 2 mm is laid underneath.

4. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The plant configuration in step S3 is specifically as follows: 0-0.4m shallow water area: 36 plants each of windmill grass, iris, and lily of the valley / m 2 Planting is staggered in a checkerboard pattern; 0.4-1m transition zone: 49 reeds / m 2 Forming a continuous strip distribution; 1-2m deep water area: Vallisneria and Hydrilla are planted at a density ratio of 2:1, with a total density of 18 plants / m 2 .

5. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The hydraulic system in step S4 includes: Water inlet unit: The perforated pipe has an opening diameter of 8mm, a hole spacing of 12cm, and is arranged in a plum blossom shape; Water outlet unit: The adjustable elbow is equipped with a 30cm diameter HDPE one-way valve, and the opening and closing pressure difference is set to 0.05MPa; Emergency unit: The diameter of the overflow pipe is DN800 and the slope is set to 2.5%.

6. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The ecological synergy system in step S5 includes: Hedgerow isolation belt: Photinia fraseri and Pittosporum tobira are planted in a ratio of 2:1, with a spacing of 0.3m between plants; Ecological buffer zone: The width of the emergent plant belt is 8m, with 25 reeds and 25 cattails per m 2 ; The third-level purification area: hydraulic retention time is controlled at 6h, 15h and 9h respectively.

7. The method for constructing an artificial wetland for lifting tailwater from a municipal sewage treatment plant according to claim 1, characterized in that: The dynamic operation and maintenance in step S6 includes: Substrate monitoring: Take three column samples with a depth of 0.5m at the water inlet, treatment area and outlet every month; Plant harvesting: Above-ground parts harvested from March 20-25, underground rhizomes dredged from October 10-15; Emergency control: When the influent NH3-N concentration exceeds 8mg / L, start the standby aeration unit and add 5g / m 3 of nitrifying bacteria.

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