An artificial natural wetland system and its purification method

Abstract

The present invention discloses an artificial natural wetland system and its purification method. Among them, the artificial natural wetland system includes an artificial ecological channel, an artificial plant ecological pond, and an artificial substrate ecological pond; wherein, the artificial ecological channel includes a flow channel and a valve arranged on the flow channel; the artificial plant ecological pond includes a plant pond and a water inlet and a water outlet respectively located on opposite sides of the plant pond; the water inlet is communicated to the flow channel; the plant pond includes a shoal area and a deep water area, the shoal area is planted with emergent plants, and the planting density is 10 - 30 plants / m²; the deep water area is planted with submerged plants, and the submerged plants cover 30 - 50% of the water surface area of the plant pond, and the biomass of the planted submerged plants is 2000 - 9000 g / m²; the artificial substrate ecological pond is communicated with the water outlet of the artificial plant ecological pond; the present invention can effectively provide the carbon source required for the denitrification of microorganisms without supplementing external carbon, and improve the nitrogen removal efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a natural wetland-like system and a purification method thereof. Background Art

[0002] An artificial wetland is a water treatment technology that uses the synergistic effect of three interdependent elements, namely soil, plants, and microorganisms, to efficiently purify pollutants through comprehensive actions such as filtration, adsorption, precipitation, ion exchange, plant absorption, and microbial degradation. Currently, in China, it is mainly used for the purpose of water quality improvement and is applied in many fields such as rural domestic sewage treatment and farmland non-point source pollution control.

[0003] Regarding the nitrogen and phosphorus removal effects of artificial wetland technology, a large number of studies have shown that biological nitrogen removal is the main mechanism for the removal of nitrogen-containing pollutants in wetland systems. Among them, nitrification-denitrification accounts for 60% - 86% of the nitrogen removal amount and is considered the most important biological pathway in wetland systems. Generally, an influent water quality C / N lower than 3 is a limiting factor for biological nitrogen removal. Insufficient organic carbon sources in water bodies will lead to low biological nitrogen removal efficiency, and external carbon sources need to be added to ensure good biological nitrogen removal effects. The phosphorus removal in artificial wetlands mainly includes three aspects: matrix filler adsorption and precipitation, plant absorption, and microbial absorption and transformation. Among them, the adsorption and precipitation of matrix fillers are the main ways for artificial wetlands to remove phosphorus. Approximately 70% of the phosphorus in sewage is removed through the adsorption and precipitation of the above-mentioned matrix fillers, and only 17% of the phosphorus is absorbed by plants.

[0004] Although the current artificial wetland technology has a wide range of application fields, there are still the following problems that need to be urgently solved for its popularization and application.

[0005] With a large amount of reclaimed water being used as landscape water to supplement rivers and lakes, the surface water environmental quality has been continuously improved. The application focus of artificial wetland technology has gradually shifted from heavily polluted water bodies to the deep purification of slightly polluted water bodies. In view of the characteristics of low-carbon, high-nitrogen, and high-phosphorus influent water, methods such as aeration optimization, matrix filler development, and addition of biological carbon sources are usually used to optimize the system. Although the above methods can effectively improve the nitrogen removal effect, there are problems of increased construction and operation costs; moreover, after adding carbon sources, risks such as matrix layer blockage and increased concentration of organic pollutants in the effluent are increased. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of traditional wetland technology, that is, for low-carbon, high-nitrogen, and high-phosphorus water bodies, external carbon needs to be added, which increases risks such as matrix layer blockage and increased concentration of organic pollutants in the effluent. Thus, a natural wetland-like system and a purification method thereof that can effectively provide the carbon source required for the denitrification of microorganisms without supplementing external carbon are provided.

[0007] A natural wetland-like system includes:

[0008] An artificial ecological channel, including a flow channel and a valve provided on the flow channel;

[0009] An artificial plant ecological pond, including a plant pond and an inlet and an outlet respectively located on opposite sides of the plant pond; the inlet is connected to the flow channel; the plant pond includes a shallow area and a deep area, and emergent plants are planted in the shallow area with a planting density of 10 - 30 plants / m 2 ; submerged plants are planted in the deep area, and the submerged plants cover 30 - 50% of the water surface area of the plant pond, and the biomass of the planted submerged plants is 2000 - 9000 g / m 2 ;

[0010] An artificial substrate ecological pond is connected to the outlet of the artificial plant ecological pond.

[0011] The above-mentioned planting biomass refers to the fresh weight of submerged plants per unit area in the deep area.

[0012] The area of the plant pond does not exceed 50,000 m 2 , the depth of the deep area is 1.5 - 2 m, and the depth of the shallow area is 0.3 - 0.7 m.

[0013] The number of the artificial plant ecological ponds is multiple, and they are connected in parallel or / and in series between the artificial ecological channel and the artificial substrate ecological pond;

[0014] The number of the artificial substrate ecological ponds is multiple, and they are connected in parallel or / and in series at the outlet of the artificial plant ecological pond.

[0015] The width of the flow channel is 2 - 4 m, and the depth does not exceed 0.8 m. Phosphorus removal fillers are provided at the bottom of the flow channel.

[0016] The artificial substrate ecological pond includes a substrate pond, several ecological interception belts arranged in the substrate pond, and a water flow inlet and a water flow outlet respectively arranged on opposite sides of the substrate pond; the water flow inlet is connected to the outlet.

[0017] The water flow inlet and the water flow outlet are connected through an overflow weir;

[0018] The area of the substrate pond does not exceed 50,000 m 2 , and the depth is 1.5 - 2 m.

[0019] The area of the plant pond is 30,000 - 50,000 m 2 , and the area of the substrate pond is 30,000 - 50,000 m 2 .

[0020] The height of the ecological interception belt is 1.5 - 2 m, and it is arranged successively along the water flow direction. The interval between two adjacent ecological interception belts along the water flow direction is 5 - 10 m. The length of the ecological interception belt in the direction perpendicular to the water flow is more than 80% of the width of the corresponding position of the substrate pond. Preferably, the length of the ecological interception belt in the direction perpendicular to the water flow is 80% - 90% of the width of the corresponding position of the substrate pond. The width of the ecological interception belt along the water flow direction is 1 - 3 m. The ecological interception belt is filled with granular calcareous gravel, and the particle size specification of the granular calcareous gravel is 1 - 3 cm.

[0021] The ecological interception belt is also filled with phosphorus-removing filler or / and modified diatom mud.

[0022] The height of the ecological interception belt is the same as the depth of the substrate pond.

[0023] The emergent plants include one or more of reed and loosestrife; the submerged plants are one or more of myriophyllum verticillatum, vallisneria natans, hydrilla verticillata, potamogeton crispus, rotala rotundifolia, and potamogeton pectinatus.

[0024] A method for purifying water body by an artificial natural wetland system includes:

[0025] The water body flows into the artificial ecological channel by self-flow through the valve, and the residence time of the water body in the artificial ecological channel is 1 - 3 d; after passing through the artificial ecological channel, the water body flows into the artificial plant ecological pond by self-flow, and the residence time of the water body in the plant pond is 6 - 17 d; the plant pond flows into the artificial substrate ecological pond by self-flow, and the residence time of the water body in the artificial substrate ecological pond is 3 - 10 d, and the purified water flows out by self-flow.

[0026] The hydraulic load of the artificial natural wetland system is 0.04 - 0.15 m 3 / (m 2 ·d).

[0027] Phosphorus-removing filler is added to the artificial ecological channel, and the mixing ratio of the phosphorus-removing filler and the soil in the artificial ecological channel is 1:5 - 1:10.

[0028] The phosphorus-removing filler is prepared by uniformly mixing bentonite and lump quicklime according to a volume ratio of 1:1 - 1:3 and drying at 105°C.

[0029] The specific surface area of the phosphorus-removing filler is 11 - 20 m 2 / g.

[0030] The technical solution of the present invention has the following advantages:

[0031] 1. In view of the low biodegradability, low-carbon, high-nitrogen and high-phosphorus characteristics of reclaimed water and slightly polluted water bodies, that is, mainly for reclaimed water and slightly polluted water bodies with a C / N ratio lower than 3, by combining the morphological characteristics of natural wetlands and biodiversity, drawing on the principles of biological nitrogen and phosphorus removal, the present invention develops an artificial-natural wetland system. The artificial ecological channels, artificial plant ecological ponds and artificial substrate ecological ponds set in this system cooperate with each other to achieve comprehensive effects such as strengthening natural interception and sedimentation, optimizing the dissolved oxygen environment, increasing the carrier area, and replenishing natural carbon-rich substances, breaking through the technical bottleneck of nitrogen and phosphorus enhanced purification in artificial-natural wetlands; specifically, the present invention uses the small-molecule organic matter secreted and released during the growth and decay periods of aquatic plants with specific densities and planting biomasses to supplement the carbon source required for the denitrification of heterotrophic microorganisms in the water body, improve the biodegradability of the water body, and enhance the denitrification effect; at the same time, the optimized setting of the specific density and planting biomass of aquatic plants also helps to strengthen the adsorption and interception of insoluble small particulate matter in the water body, cause the insoluble small particulate matter to aggregate into large particulate matter, and accelerate the sedimentation effect; in addition, compared with traditional ecological ponds, the arrangement of aquatic plants in the present invention also provides a huge enrichment area for microorganisms in the water body, providing more favorable conditions for biological nitrogen removal; at the same time, it can also promote the denitrification effect of the subsequent artificial substrate ecological pond, effectively achieving the effect of strengthening the microbial action and significantly enhancing the removal effect of total nitrogen (TN).

[0032] 2. The application of traditional wetland technologies mostly uses single forms such as subsurface flow and surface flow for construction or simple combination. In artificial wetland systems mainly aimed at water quality purification, although the system operation efficiency can be improved through measures such as structural optimization, process combination, improvement of substrate materials, and operation mode regulation, there are still problems such as a single structural form and obvious artificial construction traces, and there are still shortcomings in aspects such as the reconstruction of damaged habitats, the construction of biological communities, and the improvement of biodiversity. The artificial-natural wetland system in the present invention is a near-natural wetland system established under the background of sustainable development of ecological civilization construction, adhering to the concept of ecological nature, forming a natural spatial pattern of alternating deep pools and shallow beaches, and alternating rapid and slow flows, providing a suitable growth space for different types of aquatic plants such as submerged plants and emergent plants, providing a diverse enrichment space for microorganisms suitable for different environments, and providing diverse spawning, development, reproduction, migration and refuge places for benthic and fish aquatic animal communities at different stages of life; it can effectively promote the comprehensive improvement and healthy development of its water quality improvement and ecological restoration functions, fully meeting the inevitable trend of the development of artificial wetland technologies. Therefore, by setting up the artificial-natural wetland system of the present invention, while strengthening the water quality purification effect, it can effectively combine ecological restoration effects such as the reconstruction of damaged habitats, the construction of biological communities, and the improvement of biodiversity, as well as the purpose of landscape improvement.

[0033] 3. The present invention further optimizes the structure of the artificial substrate ecological pond. A number of ecological interception zones are provided in the artificial substrate ecological pond. The optimization of the structure of the artificial substrate ecological pond increases the interception effect on large particle and refractory pollutants, enlarges the microbial enrichment area, optimizes the dissolved oxygen environment of the water body in the traditional ecological pond, provides more suitable action conditions for denitrifying and de-nitrifying microorganisms, and further improves the removal effect of total nitrogen. Moreover, by adding materials such as phosphorus removal fillers, the adsorption and removal effect of phosphorus can be simultaneously strengthened, and the effect is more remarkable.

[0034] 4. The present invention also provides a method for purifying water body by an artificial natural wetland system. By optimizing the water retention time of the water body in the artificial ecological channel, the artificial plant ecological pond and the artificial substrate ecological pond, as well as the addition of phosphorus removal fillers in the artificial ecological channel and the artificial substrate ecological pond, and the composition and addition amount of the phosphorus removal fillers; the hydraulic load of the artificial natural wetland system of the present invention can effectively reach 0.04 - 0.15 m 3 / (m 2 ·d), significantly improving the removal effect of nitrogen and phosphorus. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 is a schematic structural diagram of the artificial natural wetland system of the present invention;

[0037] Description of the reference numerals:

[0038] 1 - artificial ecological channel, 2 - artificial plant ecological pond, 3 - artificial substrate ecological pond, 4 - overflow weir;

[0039] 11 - flow channel, 12 - valve;

[0040] 21 - shallow area, 22 - deep water area, 23 - water inlet, 24 - water outlet;

[0041] 31 - substrate pond, 32 - ecological interception zone, 33 - water flow inlet, 34 - water flow outlet. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] Embodiment 1

[0047] An artificial natural wetland system, as Figure 1 shown, includes an artificial ecological channel 1, an artificial plant ecological pond 2, and an artificial substrate ecological pond 3. Among them, the artificial ecological channel 1 includes a flow channel 11 and a valve 12 provided on the flow channel 11; the artificial plant ecological pond 2 includes a plant pond and a water inlet 23 and a water outlet 24 located on opposite sides of the plant pond respectively; the plant pond includes a shallow area 21 and a deep area 22. Emergent plants are planted in the shallow area 21, and the planting density is 10 - 30 plants / m 2 ; submerged plants are planted in the deep area 22, and the submerged plants cover 30 - 50% of the water surface area of the plant pond, and the biomass of the planted submerged plants is 2000 - 9000 g / m 2 . The water inlet 23 is connected to the flow channel 11; the artificial substrate ecological pond 3 is connected to the water outlet 24 of the artificial plant ecological pond 2.

[0048] In view of the low biodegradability, low-carbon, high-nitrogen and high-phosphorus characteristics of reclaimed water and slightly polluted water bodies, specifically for reclaimed water and slightly polluted water bodies with a C / N ratio lower than 3, the present invention develops an artificial natural wetland system by combining the form of natural wetlands and the characteristics of biodiversity and drawing on the principles of biological nitrogen and phosphorus removal. In this system, the artificially constructed ecological channels, artificial plant ecological ponds and artificial substrate ecological ponds cooperate with each other to achieve comprehensive effects such as strengthening natural interception and sedimentation, optimizing the dissolved oxygen environment, increasing the carrier area, and natural carbon-rich supply, thus breaking through the technical bottleneck of nitrogen and phosphorus enhanced purification in artificial natural wetlands. Specifically, the present invention utilizes the small-molecule organic matter secreted and released during the growth and decay periods of aquatic plants with specific density and planting biomass to supplement the carbon source required for the denitrification of heterotrophic microorganisms in the water body, improve the biodegradability of the water body, and enhance the nitrogen removal effect. At the same time, the optimized setting of the specific density and planting biomass of aquatic plants also helps to strengthen the adsorption and interception of insoluble small particulate matter in the water body, causing the insoluble small particulate matter to aggregate into large particulate matter and accelerating the sedimentation effect. In addition, compared with traditional ecological ponds, the arrangement of aquatic plants in the present invention also provides a huge enrichment area for microorganisms in the water body, providing more favorable conditions for biological nitrogen removal. At the same time, it can also promote the nitrogen removal effect of the subsequent artificial substrate ecological pond, effectively achieving the effect of strengthening the microbial action and significantly enhancing the removal effect of total nitrogen (TN).

[0049] The application of traditional wetland technologies mostly constructs or simply combines them in a single form such as subsurface flow and surface flow. In artificial wetland systems mainly aimed at water quality purification, although the system operation efficiency can be improved through measures such as structural optimization, process combination, improvement of substrate materials, and operation mode regulation, there are still problems such as a single structural form and obvious artificial construction traces, and there are still deficiencies in aspects such as the reconstruction of damaged habitats, the construction of biological communities, and the improvement of biodiversity. The artificial natural wetland system in the present invention is a near-natural wetland system established under the background of sustainable development of ecological civilization construction, adhering to the concept of ecological nature. It constitutes a natural spatial pattern with alternating deep pools and shallow beaches, and alternating rapid and slow flows, providing a suitable growth space for different types of aquatic plants such as submerged plants and emergent plants, providing a diverse enrichment space for microorganisms suitable for different environments, and providing diverse spawning, development, reproduction, migration, and refuge places for benthic and fish aquatic animal communities at different life stages. It can effectively promote the comprehensive improvement and healthy development of its water quality improvement and ecological restoration functions, fully meeting the inevitable trend of the development of artificial wetland technologies. Therefore, by setting up the artificial natural wetland system of the present invention, while strengthening the water quality purification effect, it can effectively combine ecological restoration effects such as the reconstruction of damaged habitats, the construction of biological communities, and the improvement of biodiversity, as well as the purpose of landscape improvement.

[0050] In this embodiment, in order to obtain the best effect of nitrogen and phosphorus removal, the number and structure of the artificial ecological channel 1, the artificial plant ecological pond 2, and the artificial substrate ecological pond 3 are further optimized.

[0051] Regarding the number, in this embodiment, the artificial ecological channel 1, the artificial plant ecological pond 2, and the artificial substrate ecological pond 3 can be one or multiple; when there are multiple ones, they can be arranged in parallel, in series, or in a combination of parallel and series. For example: in the artificial wetland system imitating nature in this embodiment, when the number of the artificial plant ecological ponds 2 is three, the three artificial plant ecological ponds 2 can be arranged in series between the artificial ecological channel 1 and the artificial substrate ecological pond 3, or in parallel between the artificial ecological channel 1 and the artificial substrate ecological pond 3, or two of the artificial plant ecological ponds 2 can be arranged in series and then in parallel with the remaining one artificial plant ecological pond 2 between the artificial ecological channel 1 and the artificial substrate ecological pond 3. Regarding the artificial ecological channel 1 and the artificial substrate ecological pond 3, their numbers can also be one or multiple, and when there are multiple ones, the arrangement methods can also be parallel or / and series. Any one or more of the artificial ecological channel 1, the artificial plant ecological pond 2, and the artificial substrate ecological pond 3 can be arbitrarily interspersed between the artificial ecological channel 1, the artificial plant ecological pond 2, and the artificial substrate ecological pond 3. For example: an artificial ecological channel 1 can be further arranged between the artificial plant ecological pond 2 and the artificial substrate ecological pond 3, as long as it is ensured that the water body settled through the artificial ecological channel 1 can pass through an artificial plant ecological pond 2 to achieve nitrogen removal and carbon source supplementation, and the water body after carbon source supplementation can pass through the artificial substrate ecological pond 3 to further remove suspended particles and pollutants such as nitrogen and phosphorus. The more unit structures there are, the better the water body treatment result. In this embodiment, the structure of one artificial ecological channel 1, two parallel artificial plant ecological ponds 2, and one artificial substrate ecological pond 3 is adopted.

[0052] Regarding the structure of the artificial ecological channel 1, the width of the flow channel 11 is set to 2 - 4 m, the depth does not exceed 0.8 m, and a phosphorus removal filler is provided at the bottom of the flow channel 11. The mixing ratio of the phosphorus removal filler and the soil in the artificial ecological channel is 1:5 - 1:10. In this embodiment, the width of the flow channel 11 is set to 3 m, the depth does not exceed 0.8 m, and the total length is 10 m. By volume, the mixing ratio of the phosphorus removal filler and the soil with a depth of 50 cm at the bottom of the flow channel 11 is 1:5.

[0053] Regarding the structure of the artificial plant ecological pond 2, the area of the plant pond in the artificial plant ecological pond 2 is set to not exceed 50,000 m 2 , and the area of the plant pond is preferably 30,000 - 50,000 m 2, the depth of the deep water area 22 is 1.5 - 2 m, and the depth of the shoal area 21 is 0.3 - 0.7 m; the emergent plants planted in the shoal area 21 include one or more of reed and loosestrife, and the planting density is 10 - 30 plants / m 2 ; the submerged plants planted in the deep water area 22 are one or more of Myriophyllum verticillatum, Vallisneria natans, Hydrilla verticillata, Potamogeton crispus, Myriophyllum spicatum, and Potamogeton pectinatus; the submerged plants cover 30 - 50% of the water surface area of the plant pond, and the planting biomass of the submerged plants is 2000 - 9000 g / m 2 . In this embodiment, the area of the artificial plant ecological pond 2 is set to 50,000 m 2 , the depth of the shoal area 21 is 0.5 m, mainly planted with reed, and the planting density is 10 - 15 plants / m 2 ; the depth of the deep water area 22 is 1.5 m, densely planted with one or more of Potamogeton crispus, Myriophyllum verticillatum, and Potamogeton pectinatus; the submerged plants cover about 30% of the water surface area, and the plant biomass is 2000 - 4000 g / m 2 .

[0054] For the structure of the artificial substrate ecological pond 3, the artificial substrate ecological pond 3 includes a substrate pond 31, several ecological interception zones 32 arranged in the substrate pond 31 in sequence along the water flow direction, and a water inlet 33 and a water outlet 34 respectively arranged on opposite sides of the substrate pond 31; the water inlet 33 is communicated with the water outlet 24 through an overflow weir 4. The area of the substrate pond 31 does not exceed 50,000 m 2 , and the depth is 1.5 - 2 m; the area of the substrate pond 31 is preferably 30,000 - 50,000 m 2 . Among them, the height of the ecological interception zone 32 is 1.5 - 2 m, preferably the same as the depth of the substrate pond 31. The interval between two adjacent ecological interception zones 32 along the water flow direction is 5 - 10 m, and the length of the ecological interception zone 32 perpendicular to the water flow direction is more than 80% of the width of the substrate pond 31 at the corresponding position. Preferably, the length of the ecological interception zone perpendicular to the water flow direction is 80% - 90% of the width of the substrate pond at the corresponding position. In this embodiment, the length of the ecological interception zone perpendicular to the water flow direction is basically the same as the width of the substrate pond at the corresponding position. The width of the ecological interception zone 32 along the water flow direction is 1 - 3 m. The ecological interception zone 32 is filled with granular calcareous gravel, and the particle size specification of the granular calcareous gravel is 1 - 3 cm. The ecological interception zone 32 is also filled with phosphorus removal filler or / and modified diatom mud. In this embodiment, the area of the substrate pond 31 is 50,000 m 2, with a depth of 2 m, a total of 10 ecological interception zones 32 are set, with a spacing of 10 m between adjacent ecological interception zones 32. The width of a single ecological interception zone 32 is 2 m, and the height of the ecological interception zone 32 is the same as that of the substrate pond 31. The main material of the substrate layer is granular calcareous gravel with a particle size specification of 1 - 3 cm, and a phosphorus removal filler is admixed inside. The admixing ratio of the phosphorus removal filler to the calcareous gravel is 1:10.

[0055] In this embodiment, the phosphorus removal filler used is prepared by uniformly mixing bentonite and lump quicklime in a volume ratio of 1:1 - 1:3, and then drying at 105 °C; the specific surface area of the prepared phosphorus removal filler is 11 - 20 m 2 / g, and the theoretical saturated adsorption capacity for soluble phosphate is between 0.876 - 0.992 mg / g. Specifically, the phosphorus removal filler is prepared by uniformly mixing bentonite and lump quicklime in a volume ratio of 1:2, and then drying at 105 °C. The specific surface area of the prepared phosphorus removal filler is 15 m 2 / g.

[0056] This embodiment also discloses a method for purifying water body using the above artificial natural wetland system. Among them, the water purification capacity of the above artificial natural wetland system is 0.1 - 0.3 m 3 / s, and the hydraulic retention time is 8 - 24 m 3 / s, and the hydraulic load can reach about 0.05 - 0.15 m 3 / (m 2 ·d); the specific purification process of the above artificial natural wetland system is as follows: Select the slightly polluted surface water body of a certain river in Beijing and apply it to the above artificial natural wetland system in this embodiment. The operation period is from September to December. The surface hydraulic load of the system is 0.048 m 3 / (m 2 ·d), and the continuous flow inlet mode is adopted, with an inlet flow rate of 0.1 m 3 / s. The water body flows into the artificial ecological channel by self-flow through the inlet valve, and the residence time of the water body in the artificial ecological channel is 3 d; after passing through the artificial ecological channel, the water body flows into the artificial plant ecological pond by self-flow, and the residence time of the water body in the plant pond is 17 d; the plant pond flows into the artificial substrate ecological pond by self-flow, and the residence time of the water body in the artificial substrate ecological pond is 8 d, and the purified water flows out by self-flow after that.

[0057] The average concentrations of the main pollutant indicators COD Cr , TN, TP, and ammonia nitrogen in the influent are 24.3 mg / L, 2.89 mg / L, 0.4 mg / L, and 0.55 mg / L respectively, and the water quality indicators fluctuate between surface water class Ⅳ and class Ⅴ.

[0058] After purification by the artificial natural wetland system, the average concentrations of the above pollutants in the effluent are reduced to 19.4 mg / L, 1.8 mg / L, 0.18 mg / L and 0.3 mg / L respectively, and all indicators basically stably reach the standard better than Class IV of surface water. COD Cr The average removal rates of indicators such as TN, TP and ammonia nitrogen reach 21.11%, 33.73%, 57.41% and 35.58% respectively.

[0059] Specifically, the relative average removal rates of COD Cr , TN, TP and ammonia nitrogen by the artificial ecological channel 1 reach 7.05%, 17.99%, 48.9% and 38% respectively; the relative average removal rates of COD Cr , TN, TP and ammonia nitrogen by the artificial plant ecological pond 2 reach 10%, 14.5%, 6.06% and 6.5% respectively. The average removal rates of the above pollutants by the artificial substrate ecological pond 3 are 1.96%, 7.24%, 19.78% and 11.88% respectively.

[0060] Example 2

[0061] The difference between this example and Example 1 is that the specific structures of the artificial ecological channel 1, the artificial plant ecological pond 2 and the artificial substrate ecological pond 3 are different from those in Example 1, and the specific settings are as follows:

[0062] Regarding the structure of the artificial ecological channel 1, in this example, the width of the flow channel 11 is set to 3 m, the depth does not exceed 0.8 m, and the total length is 10 m. By volume ratio, the mixing ratio of the phosphorus-removing filler in the soil 50 cm deep at the bottom of the flow channel 11 is 1:10.

[0063] Regarding the structure of the artificial plant ecological pond 2, in this example, the area of the artificial plant ecological pond 2 is set to 50,000 m 2 , the depth of the shoal area 21 is 0.5 m, mainly planted with reeds, and the planting density is 10 - 15 plants / m 2 ; the depth of the deep water area 22 is 2 m, densely planted with one or more of submerged plants such as Vallisneria natans, Myriophyllum verticillatum, Potamogeton pectinatus, Hydrilla verticillata; the submerged plants cover about 45% of the water surface area, and the plant biomass is 6000 - 9000 g / m 2 .

[0064] Regarding the structure of the artificial substrate ecological pond 3, in this example, the area of the substrate pond 31 is 50,000 m 2, with a depth of 1.5 m, there are 10 ecological intercepting belts 32 in total. The interval between two adjacent ecological intercepting belts 32 is 10 m. The width of a single ecological intercepting belt 32 is 2 m, and the height of the ecological intercepting belt 32 is 2 m. The main material of the substrate layer is granular calcareous gravel with a particle size specification of 1 - 3 cm, and a phosphorus removal filler is admixed inside. The admixing ratio of the phosphorus removal filler to the calcareous gravel is 1:10.

[0065] This embodiment also discloses a method for purifying water body by using the above-mentioned natural wetland-like system. The specific process is as follows: Select the slightly polluted surface water of a certain river in Beijing and apply it to the above-mentioned natural wetland-like system in this embodiment. The operation period is from April to August. The surface hydraulic load of this system is 0.14 m 3 / (m 2 ·d), and the continuous flow inlet mode is adopted, with an inlet flow rate of 0.3 m 3 / s. The water body enters the artificial ecological channel by gravity through the inlet valve, and the residence time of the water body in the artificial ecological channel is 1 d; after passing through the artificial ecological channel, the water body flows into the artificial plant ecological pond by gravity, and the residence time of the water body in the plant pond is 6 d; the plant pond flows into the artificial substrate ecological pond by gravity, and the residence time of the water body in the artificial substrate ecological pond is 3 d. After purification, the effluent flows out by gravity.

[0066] The average concentrations of the main pollutant indicators COD Cr , TN, TP, and ammonia nitrogen in the influent are 24.67 mg / L, 2.81 mg / L, 0.12 mg / L, and 0.088 mg / L respectively.

[0067] After being purified by the natural wetland-like system, the average concentrations of the above pollutant indicators in the effluent are reduced to 22.6 mg / L, 1.2 mg / L, 0.062 mg / L, and 0.05 mg / L respectively. The average removal rates of the indicators such as COD Cr , TN, TP, and ammonia nitrogen reach 8.11%, 56.89%, 49.18%, and 43.02% respectively.

[0068] Specifically, the relative average removal rates of COD Cr , TN, TP, and ammonia nitrogen by the artificial ecological channel 1 reach 5%, 4.7%, 20%, and 13% respectively; the artificial plant ecological pond 2 for COD CrThe relative average removal rates of COD, TN, TP, and ammonia nitrogen reached 3%, 35.24%, 14.67%, and 10% respectively. The average removal rates of the above pollutants by the artificial substrate ecological pond 3 were 14%, 44.06%, 22.95%, and 11.3% respectively. The relative removal efficiency of COD by the above artificial plant ecological pond 2 was relatively low, which was related to the organic substances secreted by the plants. Some of the organic substances were regarded as organic carbon sources, creating favorable conditions for the denitrification of heterotrophic microorganisms. At the same time, the C / N in the water discharged from this unit increased from 1.2 to 4.3, and the biodegradability increased significantly.

[0069] The surface hydraulic load of the artificial natural wetland system is higher than that of the traditional surface flow artificial wetland, and its operation effect is better than that of the traditional surface flow wetland in purifying TN and TP in slightly polluted water bodies.

[0070] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. An artificial natural wetland system, characterized in that, it includes: An artificial ecological channel (1), including a flow channel (11) and a valve (12) arranged on the flow channel (11); Artificial plant ecological pond (2), comprising a plant pond, and an inlet (23) and an outlet (24) respectively located on opposite sides of the plant pond; the inlet (23) is connected to the flow channel (11); the plant pond includes a shallow area (21) and a deep area (22), emergent plants are planted in the shallow area (21), and the planting density is 10 - 30 plants / m 2 ; submerged plants are planted in the deep area (22), and the submerged plants cover 45 - 50% of the water surface area of the plant pond, and the biomass of the planted submerged plants is 6000 - 9000 g / m 2 ; An artificial substrate ecological pond (3), which is connected to the water outlet (24) of the artificial plant ecological pond (2); the water body entering the artificial ecological channel (1) through the valve (12) is reclaimed water and slightly polluted water with a C / N lower than 3; The submerged plants are one or more of Myriophyllum verticillatum, Vallisneria natans, Hydrilla verticillata, Potamogeton crispus, Ceratophyllum demersum, Potamogeton pectinatus.

2. The artificial natural wetland system according to claim 1, characterized in that, The area of the plant pond does not exceed 50,000 m 2 , the depth of the deep water area (22) is 1.5 - 2 m, and the depth of the shoal area (21) is 0.3 - 0.7 m.

3. The artificial natural wetland system according to claim 1 or 2, characterized in that, The number of the artificial plant ecological ponds (2) is multiple, which are connected in parallel or / and in series between the artificial ecological channel (1) and the artificial substrate ecological pond (3); The number of the artificial substrate ecological ponds (3) is multiple, which are connected in parallel or / and in series on the water outlet (24) of the artificial plant ecological pond (2).

4. The artificial natural wetland system according to claim 1 or 2, characterized in that, The width of the flow channel (11) is 2 - 4 m, the depth does not exceed 0.8 m, and a phosphorus removal filler is arranged at the bottom of the flow channel (11).

5. The artificial natural wetland system according to claim 1 or 2, characterized in that, The artificial substrate ecological pond (3) includes a substrate pond (31), several ecological interception belts (32) arranged in the substrate pond (31), and a water inlet (33) and a water outlet (34) respectively arranged on opposite sides of the substrate pond (31); the water inlet (33) is connected to the water outlet (24).

6. The artificial natural wetland system according to claim 5, characterized in that, The water inlet (33) is connected to the water outlet (24) through an overflow weir (4); The area of the substrate pond (31) does not exceed 50,000 m 2 , and the depth is 1.5 - 2 m.

7. The artificial natural wetland system according to claim 6, characterized in that, The area of the plant pond is 30,000 - 50,000 m 2 , and the area of the substrate pond (31) is 30,000 - 50,000 m 2 .

8. The artificial natural wetland system according to claim 6 or 7, characterized in that, The height of the ecological interception belt (32) is 1.5 - 2 m, which are arranged in sequence along the water flow direction, the interval between two adjacent ecological interception belts (32) along the water flow direction is 5 - 10 m, the length of the ecological interception belt (32) perpendicular to the water flow direction is 80% - 90% of the width of the corresponding position of the substrate pond (31), the width of the ecological interception belt (32) along the water flow direction is 1 - 3 m, and the ecological interception belt (32) is filled with granular calcareous gravel, and the particle size specification of the granular calcareous gravel is 1 - 3 cm.

9. The artificial natural wetland system according to claim 8, characterized in that, The ecological interception belt (32) is also filled with a phosphorus removal filler or / and modified diatom mud.

10. The artificial natural wetland system according to claim 6 or 7, characterized in that, The height of the ecological interception belt (32) is the same as the depth of the substrate pond (31).

11. The artificial natural wetland system according to claim 1 or 2, characterized in that, The emergent plants include one or more of Phragmites australis, Lythrum salicaria.

12. A method for purifying water body by an artificial natural wetland system according to any one of claims 1-11, characterized in that, it includes: The water body flows into the artificial ecological channel by gravity through a valve, and the residence time of the water body in the artificial ecological channel is 1-3 days; After passing through the artificial ecological channel, the water body flows into the artificial plant ecological pond by gravity. The residence time of the water body in the plant pond is 6-17 days; the plant pond flows into the artificial substrate ecological pond by gravity. The residence time of the water body in the artificial substrate ecological pond is 3-10 days, and the purified water flows out by gravity after that; The hydraulic load of the artificial natural wetland system is 0.04 - 0.15 m 3 / (m 2 ·d).

13. The method according to claim 12, characterized in that, phosphorus-removing fillers are added to the artificial ecological channel, and the mixing ratio of the phosphorus-removing fillers to the soil in the artificial ecological channel is 1:5-1:

10.

14. The method according to claim 13, characterized in that, the phosphorus-removing fillers are prepared by uniformly mixing bentonite and lump quicklime in a volume ratio of 1:1-1:3 and then drying at 105 °C.

15. The method according to claim 14, characterized in that, The specific surface area of the phosphorus removal filler is 11 to 20 m 2 / g.

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