Constructed wetland purification system and method

Abstract

The present application relates to the technical field of ecological water treatment, and particularly relates to an artificial wetland technology comprising a two-stage synergistic purification system and a dynamic regulation and control purification method. The system comprises: an upstream ecological regulation and storage circulation unit composed of n series of regulation and storage pools, a serpentine water flow channel is formed by 85-95 degree staggered dikes in the pool, and the hydraulic retention time is extended to 36-48 hours; a downstream ecological purification unit comprising parallel ecological islands, a zoned purification filter bed and a three-stage ecological gain pond. The overall ammonia nitrogen / total phosphorus removal rate is 70% and 60% respectively, the bird habitat density is increased to 3.8 per hectare, and the aeration energy consumption is reduced. The present application solves the problems of low hydraulic efficiency, weak ecological function and response lag of traditional wetlands, and is suitable for river and lake pollution control and ecological restoration.

Description

Technical Field

[0001] This invention relates to the field of ecological water treatment technology, specifically to an artificial wetland technology comprising a two-stage synergistic purification system and a dynamic control purification method, used to improve pollutant removal efficiency and ecosystem service functions. Background Technology

[0002] Constructed wetland technology, as a green infrastructure that combines ecological restoration and wastewater treatment, has become a research hotspot in the field of water environment management. Although traditional constructed wetland systems can remove pollutants through plant absorption, microbial degradation, and matrix filtration, their treatment efficiency is limited by technical bottlenecks such as short hydraulic retention time, uneven dissolved oxygen distribution, and limited biodiversity. Especially when dealing with water bodies heavily polluted by nitrogen and phosphorus, they generally suffer from problems such as large fluctuations in pollutant removal rates, limited ecosystem service functions, and insufficient operational stability.

[0003] In existing technologies, constructed wetland systems mostly adopt a single-stage series or parallel layout, with linear water flow paths. This leads to the formation of short-flow dead zones in the upstream area, while the downstream area suffers from reduced organic matter concentration, weakening the metabolic activity of microorganisms. In addition, traditional wetland systems do not make sufficient use of topographic features and fail to construct a multi-stage hydraulic circulation system, resulting in limited reoxygenation capacity of the water body and restricting the growth and reproduction of aerobic microbial communities.

[0004] In the ecological purification stage, existing technologies mostly employ single-function purification units, such as relying solely on plant absorption or matrix adsorption, lacking a synergistic mechanism of biological manipulation and habitat creation. Furthermore, traditional wetland systems suffer from insufficient adaptation to topographic features and fail to construct multi-stage treatment units based on surface runoff path analysis, thus limiting the effectiveness of pollutant degradation in a cascade manner.

[0005] To address the aforementioned technical deficiencies, the following technical bottlenecks urgently need to be overcome in this field: First, construct an intelligent hydraulic control system to achieve dynamic matching between hydraulic residence time and dissolved oxygen concentration; second, develop a multi-level synergistic purification system to enhance biodiversity through terrain reshaping and habitat creation; and third, establish a dual optimization mechanism for pollutant removal and ecosystem service functions to overcome the limitations of traditional single-function technologies.

[0006] Based on the aforementioned needs, this invention innovatively proposes a two-level collaborative processing unit architecture by deeply integrating wetland topographic feature analysis with hydraulic control technology. This provides an innovative solution for the intelligent upgrading and ecological benefit enhancement of constructed wetland technology. Summary of the Invention

[0007] I. Technical Issues 1. The hydraulic efficiency of constructed wetland systems is low and their ecological functions are weak, resulting in insufficient synergy. 2. Lack of dynamic control strategies based on multi-source data.

[0008] II. Technical Solution To address the above problems, the present invention provides an artificial wetland purification system, comprising: The upstream ecological regulation and circulation unit consists of n series-connected regulation tanks, where n>1. Adjacent regulation tanks are connected by culverts, and groynes are staggered within the tanks to form a serpentine water flow channel perpendicular to the main water flow axis. The downstream ecological purification unit includes ecological islands, ecological purification filter beds, and ecological enhancement ponds arranged in parallel. The coordinated connection component connects the end of the upstream ecological regulation and circulation unit with the beginning of the downstream ecological purification unit through a culvert, and a pumping station is set up at the end of the downstream ecological purification unit to regulate the water level.

[0009] Preferably, the groynes are arranged at an angle of 85°-95°, and an array of ecological floating islands is set on the water-facing side of the groynes, with plants for removing nitrogen and phosphorus planted in the array.

[0010] Preferably, the dead water zone of the regulating tank is equipped with a solar aeration system, and the aeration intensity of the solar aeration system is dynamically adjusted based on feedback from a dissolved oxygen sensor.

[0011] Preferably, the slope ratio of the ecological island is 1:8–1:12, the top height is 1m above the normal water level, and the surface is planted with berry shrubs.

[0012] Preferably, the berry-bearing shrubs include paper mulberry and firethorn.

[0013] Preferably, the ecological purification filter bed comprises: In shallow water areas with a depth of 0.5–0.7m, emergent plant belts are laid out, including a complex rhizosphere oxidation community of reeds and cattails; In the deep water area with a depth of 0.7–1.0m, a combined submerged-floating plant zone is set up, including a combination of Vallisneria natans and water lilies.

[0014] Preferably, the ecological enhancement pond includes: Plant Vallisneria natans and water shield in the deep water area; Mixed planting of water chestnut and water bamboo in shallow water areas; The ecological enhancement pond is equipped with a three-tiered trophic cascade system consisting of plankton, fish, shrimp, shellfish, snails, and filter-feeding fish.

[0015] Preferably, the culvert is equipped with a water level sensor and an automatic opening and closing device to dynamically adjust the water level difference according to the upstream inflow and downstream purification requirements.

[0016] On the other hand, the present invention also provides a method for purifying constructed wetlands, based on the above-mentioned constructed wetland purification system, comprising the following steps: S1. By using groynes arranged at 85°-95° ​​intervals, the water flow path is extended by more than 30%; S2. Construct a three-tiered trophic cascade system in the ecological enhancement pond, with a stocking density of ≥5 individuals / m². 2 Filter-feeding shellfish and those with a density ≤0.5kg / m³ 3 Filter-feeding fish; S3. The intensity of solar aeration is dynamically adjusted based on dissolved oxygen data, and the pump station's drainage volume is controlled by feedback from the water level sensor.

[0017] III. Beneficial Effects This invention extends the hydraulic retention time to 36-48 hours through a serpentine flow channel formed by staggered groynes at 85°-95° ​​within the upstream regulating reservoir, increasing the contact efficiency between pollutants and plants / microorganisms by over 50%. Simultaneously, the turbulence induced by the spatial arrangement of the groynes enhances dissolved oxygen diffusion, resulting in an ammonia nitrogen removal rate of 70%, fundamentally solving the problem of low hydraulic efficiency in traditional wetlands. Furthermore, based on real-time feedback of dissolved oxygen and dynamic control of solar-powered aeration, the dissolved oxygen concentration in stagnant water zones is stabilized within a constant range. This not only prevents secondary release of pollutants caused by anaerobic environments but also reduces energy waste compared to a fixed mode by adjusting the aeration intensity as needed, achieving a dual breakthrough in energy conservation and pollution control.

[0018] More significantly, the systemic proliferation of ecosystem services is evident: on the one hand, the berry shrubs (paper mulberry / firethorn) on the ecological island and the three-level trophic cascade (plankton → shellfish → filter-feeding fish) of the enrichment pond synergistically attract birds, resulting in a habitat density of 3.2 birds / hectare; on the other hand, emergent plants (reed / cattail) and submerged plants (valley grass / water lily) configured according to water depth gradient zones construct a three-dimensional symbiotic system of rhizosphere oxidation-matrix adsorption-microbial degradation, achieving a total phosphorus removal rate of up to 60%, significantly enhancing the ecological self-purification capacity.

[0019] The synergistic optimization of water level linkage control and biological manipulation in this invention has achieved remarkable results: the sluice gate dynamically adjusts the water level difference according to the inflow rate, the pumping station maintains the optimal water depth, and the submerged plants receive sufficient sunlight. With the addition of filter-feeding shellfish and fish in a gradient manner, the survival rate is increased to 85%, forming a sustainable ecological purification closed loop.

[0020] In summary, this invention, with hydraulic regulation as its foundation, biological proliferation as its efficiency enhancement, and intelligent collaborative optimization as its core, simultaneously achieves efficient degradation of pollutants, ecosystem enhancement, and refined energy consumption control, thus completely bridging the contradiction between pollution control and ecological function in traditional technologies. Attached Figure Description

[0021] This manual includes the following figures, which illustrate the following: Figure 1 This is a schematic diagram of the purification system structure according to Embodiment 1 of the present invention; In the diagram: 1. Regulating reservoir; 2. Culvert; 3. Groynes; 4. Water flow channel; 5. Ecological island; 6. Ecological purification filter bed; 7. Ecological enhancement pond; 8. Pump station; 9. Aeration system; 10. Ecological floating island. Detailed Implementation

[0022] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0023] Example 1: This embodiment provides an artificial wetland purification system. Taking a wetland restoration project at the estuary of the lower Yangtze River as an application scenario, the system covers an area of ​​approximately 15 hectares and is designed to treat 3000 cubic meters of water per day. The upstream ecological regulation and circulation unit consists of four series-connected regulation tanks 1, each with an area of ​​approximately 200 square meters and a depth of 1.5 meters. The tanks are connected by steel culverts 2 with a width of 1.5 meters, and the gate opening and closing stroke is controlled within 0-100 centimeters. Groynes 3 are vertically arranged within the tanks along the main water flow direction. After optimization through fluid dynamics simulation, the angle of the groynes 3 is set at 89.3°±1.5°. The groynes 3 are made of reinforced concrete, with their top elevation 0.3 meters above the normal water level. They are spaced apart to form a serpentine water flow channel 4 with a total length of 210 meters, extending the water flow path by 42% compared to a straight line.

[0024] Ten ecological floating islands are installed on the water-facing side of groynes 3. The island frames are made of high-density polyethylene, with each module measuring 1 meter x 1 meter. The reeds and cattails planted on the islands are sourced from a local wetland nursery. In the stagnant water area of ​​regulating reservoir 1, twelve solar-powered aeration systems are installed, each equipped with a 200-watt monocrystalline silicon photovoltaic panel and a 2.2-kilowatt oil-free air compressor. The aeration intensity is monitored and fed back in real time by a Hach HQ40d dissolved oxygen sensor, automatically increasing the aeration rate when the dissolved oxygen level falls below the standard value.

[0025] The downstream ecological purification units adopt a parallel layout, as detailed below: Ecological Island 5 was constructed using excavated earthwork, with a base area of ​​120 square meters and a slope of 1:10. The top elevation of the island was set at 1.05 meters above the normal water level, and a total of 330 paper mulberry and firethorn trees were planted on the surface, with a spacing of 0.6 meters between the trees.

[0026] The ecological purification filter bed is divided into a shallow water area and a deep water area: the shallow water area has a water depth of 0.65 meters, with a planting density of 8 reeds per square meter and 4 cattails per square meter to form a complex rhizosphere oxidation community; the deep water area has a water depth of 0.88 meters, with a coverage rate of 75% for Vallisneria natans and water lilies arranged at a spacing of 1.2 meters.

[0027] The bottom of Ecological Enhancement Pond 7 is sloped to create deep and shallow water zones. When the water level at Pump Station 8 is 0.78 meters, the deep water zone has a depth of 0.88 meters. In the deep water zone of Ecological Enhancement Pond 7, Vallisneria natans and Water Shield are planted, while in the shallow water zone, Water Chestnut and Wild Rice are mixed, with planting densities of 6 plants per square meter and 4 plants per square meter, respectively. The pond's three-tiered trophic cascade system includes: a plankton propagation zone, a filter-feeding shellfish stocking zone, and a filter-feeding fish farming zone. Optionally, the algae density in the plankton propagation zone is 1.2 × 10⁻⁶. 5 The density of snails in the filter-feeding shellfish breeding area was 7.3 per square meter, and the density of silver carp in the filter-feeding fish breeding area was 0.47 kg per cubic meter.

[0028] In the coordinated connection component, culvert 2 is equipped with a Siemens ultrasonic level gauge with a range of 0-2 meters. Based on data from the upstream inflow sensor, when the flow rate exceeds 12 cubic meters per hour, the automatic opening and closing device increases the gate opening to 85%. A submersible pumping station 8 is installed at the downstream end, with a drainage capacity of 10 cubic meters per hour. A PID controller maintains the water level at pumping station 8 within the range of 0.78 ± 0.05 meters, thereby achieving dynamic water level control. The automatic opening and closing device can be a winch-type gate opener, a hydraulic gate opener, etc., as long as it can achieve automatic gate opening and closing. This technology has long been maturely applied in water conservancy projects; therefore, its specific structure and working principle will not be described in detail in this embodiment.

[0029] In this embodiment, the hydraulic retention time reaches 45 hours through the serpentine water flow channel 4; the three-level trophic cascade system attracts 7 species of birds, including black-crowned night herons and kingfishers, with a density of 3.8 birds per hectare; the removal rates of ammonia nitrogen and total phosphorus are 70% and 60%, respectively, which are significantly superior to industry standards.

[0030] Example 2: This embodiment provides a method for purifying artificial wetlands, which is based on the purification system of Embodiment 1.

[0031] Specifically, the location of groynes 3 was precisely determined using a total station, ensuring that the average angle between groynes 3 and the main water flow axis was 89.6° with a standard deviation of 0.8°. Velocity profilers measured the original straight path length, which increased from 183 meters to 257 meters, a 40.4% increase. The turbulence intensity increased to 0.28, improving oxygen mass transfer efficiency and increasing the uniformity of dissolved oxygen distribution by 62%, thus laying a favorable foundation for downstream biological colonization.

[0032] Gradual biological introduction was implemented in ecological enhancement pond 7: Plankton proliferation: A mixed diatom and green algae spore strain was introduced, reaching a density of 1.5 × 10⁻⁶. 5 One per liter; Filter-feeding shellfish were introduced: snails (shell height 3.5±0.3 cm) and river clams (shell length 2.8±0.2 cm) were selected, with densities of 6.8 per square meter and 5.2 per square meter, respectively, for a total density of 12 per square meter; Filter-feeding fish stocking: Silver carp (body length 15±2 cm) and bighead carp (body length 18±2 cm) were stocked at a ratio of 3:2, with a biomass density of 0.49 kg per cubic meter.

[0033] When the dissolved oxygen sensor detects that the dissolved oxygen level is below 3.9 mg / L for 20 consecutive minutes, the DSP controller instructs to increase the aeration intensity to 1.15 L / min / m³, and restores the dissolved oxygen level to 5.1 mg / L within 2 to 3 hours; When the water level sensor detects that the downstream water depth exceeds 1.02 meters, the pumping station 8 increases its drainage capacity from 7 cubic meters per hour to 11 cubic meters per hour to ensure that the water level drops back to about 0.78 meters within 24 hours.

[0034] This embodiment significantly improves the system's resistance to shock loads using the methods described above. Under extreme rainstorm conditions with a sudden 120% increase in influent flow, the ammonia nitrogen removal rate remains at 70%; the natural proliferation rate of shellfish reaches 23.5%, and the survival rate is 91.2%; energy-saving analysis shows that aeration energy consumption is reduced by 39.7%.

[0035] In summary, this invention constructs a serpentine water flow channel 4 by using staggered groynes 3 at 85°-95° ​​upstream, significantly extending the hydraulic residence time to 36–48 hours. Combined with a downstream three-stage trophic cascade system, it achieves an ammonia nitrogen removal rate of 70% and a total phosphorus removal rate of 60%. This "structural optimization-intelligent sensing-precise control" three-in-one model overcomes the three major bottlenecks of traditional wetlands: low hydraulic efficiency, weak ecological function, and delayed response, providing an innovative paradigm for water ecological governance.

[0036] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An artificial wetland purification system, characterized in that, include: The upstream ecological regulation and circulation unit consists of n series-connected regulation tanks (1) with n>1. Adjacent regulation tanks (1) are connected by culverts (2). The tanks are arranged with groynes (3) perpendicular to the main water flow axis to form a serpentine water flow channel (4). The downstream ecological purification unit includes an ecological island (5), an ecological purification filter bed (6), and an ecological enhancement pond (7) arranged in parallel. The coordinated connection component connects the end of the upstream ecological regulation and circulation unit with the beginning of the downstream ecological purification unit through the culvert (2), and sets up a pump station (8) at the end of the downstream ecological purification unit to regulate the water level; The groynes (3) are arranged at an angle of 85°-95°, and an array of ecological floating islands (10) is set on the water-facing side of the groynes (3). The array of ecological floating islands (10) is planted with plants that remove nitrogen and phosphorus. The dead water zone of the storage tank (1) is equipped with a solar aeration system (9), and the aeration intensity of the solar aeration system (9) is dynamically adjusted based on the feedback from the dissolved oxygen sensor. The ecological purification filter bed (6) includes: In shallow water areas with a depth of 0.5–0.7m, emergent plant belts are laid out, including a complex rhizosphere oxidation community of reeds and cattails; In the deep water area with a depth of 0.7–1.0m, a combined submerged-floating plant zone is set up, including a combination of Vallisneria natans and water lilies; The ecological enhancement pond (7) includes: Plant Vallisneria natans and water shield in the deep water area; Mixed planting of water chestnut and water bamboo in shallow water areas; An ecological enhancement pond (7) is constructed with a three-level trophic cascade system consisting of plankton, fish, shrimp, shellfish, snails, and filter-feeding fish. The culvert (2) is equipped with a water level sensor and an automatic opening and closing device, which dynamically adjusts the water level difference according to the upstream inflow and downstream purification needs.

2. The constructed wetland purification system according to claim 1, characterized in that: The slope ratio of the ecological island (5) is 1:8–1:12, the top height is 1m above the normal water level, and the surface is planted with berry shrubs.

3. The constructed wetland purification system according to claim 2, characterized in that: The berry-bearing shrubs include paper mulberry and firethorn.

4. A method for purifying constructed wetlands, implemented based on the constructed wetland purification system according to any one of claims 1-3, characterized in that, Including the following steps: S1. By using groynes (3) arranged at 85°-95°, the water flow path is extended by more than 30%; S2. Construct a three-level trophic cascade system in the ecological enhancement pond (7), with a stocking density of ≥5 individuals / m². 2 Filter-feeding shellfish and those with a density ≤0.5kg / m³ 3 Filter-feeding fish; S3. The intensity of solar aeration is dynamically adjusted based on dissolved oxygen data, and the drainage volume of the pump station (8) is controlled by feedback from the water level sensor.

Images