Ecological treatment process and structure for tail water purification

Abstract

The invention relates to a tail water purification ecological treatment process and structure, and relates to the technical field of tail water purification, and the tail water purification ecological treatment process comprises the following steps: S1, ecological enhancement area treatment: tail water is primarily purified through a composite ecological filter bed, an artificial aquatic plant purification zone, a three-dimensional ecological floating bed and a stain-resistant plant purification zone; s2, treatment in an ecological buffer area: introducing the effluent of the ecological enhancement area into the ecological buffer area, and carrying out secondary purification on the tail water by virtue of submerged plants in the ecological buffer area; s3, treating in an ecological display area, introducing the tail water treated in the ecological buffer area into the ecological display area, and purifying the tail water for the third time; and S4, treating an ecological stable area, constructing an aquatic plant community in the ecological stable area, adding zooplankton, benthonic animals and microorganisms to optimize the community, and purifying the tail water for four times. Fish participation is not needed, nitrogen is directly removed through microorganism-plant cooperation, animals only assist in removing impurities, no additional nitrogen load exists, and therefore the stability of the system can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of tail water purification, and in particular to an ecological treatment process and structure for tail water purification. Background Art

[0002] With the urban development and construction, the scale of urban sewage treatment is gradually increasing. Considering the environmental capacity, it is necessary to further treat the tail water of urban sewage treatment plants.

[0003] The invention publication number CN108793646B discloses a landscape-type domestic sewage ecological treatment system. In the specification, omnivorous fish other than silver carp that feed on phytoplankton are put in the biological cultivation oxidation pond I, biochemical cultivation oxidation pond II and decomposition pond, such as snakehead fish, catfish, carp, crucian carp, icefish, ornamental fish and snails, etc. Omnivorous fish (such as snakehead fish, carp, etc.) and filter-feeding fish (such as silver carp, bighead carp) are introduced, and the microbial community is indirectly affected by feeding on algae and plankton. In the relevant prior art, the fish excrement increases the ammonia nitrogen load, which will interfere with the denitrification efficiency, and the death of fish leads to water quality deterioration, or over-reproduction leads to system collapse, resulting in poor stability of the tail water purification system. Summary of the Invention

[0004] In order to improve the problems that the death of fish leads to water quality deterioration, or over-reproduction leads to system collapse, resulting in poor stability of the tail water purification system, the present application provides an ecological treatment process and structure for tail water purification.

[0005] The ecological treatment process and structure for tail water purification provided by the present application adopt the following technical solutions: An ecological treatment process for tail water purification includes the following steps: S1. Treatment in the ecological strengthening area: The tail water is introduced into the ecological strengthening area, and the tail water is preliminarily purified by passing through a composite ecological filter bed, an artificial waterweed purification belt, a three-dimensional ecological floating bed and a pollution-tolerant plant purification belt in sequence; S2. Treatment in the ecological buffer area: The effluent from the ecological strengthening area is introduced into the ecological buffer area, and the tail water is secondarily purified by the submerged plants in the ecological buffer area. The submerged plants are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Ceratophyllum demersum: Potamogeton malaianus: Potamogeton pectinatus = 6:1:1:1:1; S3. Treatment in the ecological display area: In the shallow water area of the ecological display area, the plants are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus = 8:1:1, and in the deep water area, they are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus = 1:6:3. The tail water after the treatment in the ecological buffer area is introduced into the ecological display area to perform tertiary purification on the tail water; S4. Treatment in the ecological stabilization area: Submerged plants, floating-leaved plants and emergent plants are arranged in the ecological stabilization area to construct an aquatic plant community, and then zooplankton, benthic animals and microorganisms are put in to optimize the community. The tail water after the treatment in the ecological display area is introduced into the ecological stabilization area to perform quaternary purification on the tail water.

[0006] By adopting the above technical solutions, the tail water undergoes multi-stage treatment in the ecological enhancement area, ecological buffer area, ecological display area and ecological stability area, and finally realizes efficient purification. In the ecological enhancement area, the compound ecological filter bed removes pollutants in water through physical filtration, chemical adsorption and biodegradation. The artificial waterweed purification zone provides a large specific surface area to promote the attachment of microorganisms, and the three-dimensional ecological floating bed and pollution-tolerant plant purification zone further reduce the pollution load. Subsequently, in the ecological buffer area, the submerged plants with reasonable proportion are used to secondary purify the tail water, effectively removing residual organic matter and nitrogen and phosphorus nutrients. After entering the ecological display area, the planting ratio is optimized according to different water area conditions, taking into account both the purification effect and the landscape requirements. Finally, in the ecological stability area, various aquatic plants are comprehensively arranged, and planktonic animals, benthic animals and microorganisms are put in to form a healthy ecosystem food chain, significantly improving the water self-purification ability and stability, and ensuring that the effluent meets the Class III water quality standard of the Environmental Quality Standards for Surface Water (TN≤1.5mg / L). There is no fish interference in the solution of this application. A stable ecological barrier is formed by submerged plants (coverage rate ≥80%) and microbial communities. The microorganisms and plants cooperate directly to denitrify, and the animals only assist in removing impurities without additional nitrogen load, thus enabling the purification system to be stable.

[0007] Preferably, the compound ecological filter bed includes a gravel bed, filter media, emergent plants and an aeration pipe, and removes nitrogen and phosphorus through the synergistic action of physical filtration, chemical adsorption and biofilm, wherein: the sewage retention time is 1.3 - 1.7 hours; the porosity of the filter media is 70% - 75%; the filtration rate is 0.5 - 0.7 m / h; the aeration intensity is 18 - 22 L / (m²·s).

[0008] By adopting the above technical solutions, the sewage retention time is set to 1.3 - 1.7 hours, ensuring sufficient reaction time to fully remove pollutants. Secondly, the porosity of the filter media is controlled at 70% - 75%, which not only ensures good filtration performance but also maintains appropriate permeability to avoid clogging. At the same time, the design parameter of the filtration rate of 0.5 - 0.7 m / h can reduce energy consumption on the basis of ensuring the treatment efficiency. Finally, the aeration intensity is set to 18 - 22 L / (m²·s), which promotes the metabolic activities of aerobic microorganisms, improves the nitrification efficiency, and finally realizes the effect of efficient nitrogen and phosphorus removal.

[0009] Preferably, the filter media has a porous structure so that microorganisms can attach to the filter media and form aerobic and anoxic zones. The microorganisms carry out nitrification reactions in the aerobic zone and denitrification reactions in the anaerobic zone.

[0010] By adopting the above technical solutions, the porous structure of the filter material significantly increases the attachment area of microorganisms, forming a rich biofilm. The biofilm is naturally stratified inside, with the coexistence of aerobic and anoxic zones, thus realizing the process of simultaneous nitrification and denitrification. This design effectively improves the nitrogen removal efficiency, simplifies the process flow, reduces energy consumption and operating costs, and ensures that the effluent quality meets the standards stably.

[0011] Preferably, in the artificial aquatic plant purification zone, the specific surface area of the artificial aquatic plants is ≥ 250 m² / m², the tensile strength is ≥ 10 KN / m, and the laying density is 8 - 12 plants / m².

[0012] By adopting the above technical solutions, the artificial aquatic plants in the artificial aquatic plant purification zone have a large specific surface area, can effectively adsorb pollutants in water, and improve the purification efficiency. At the same time, the high tensile strength ensures the stability of the artificial aquatic plants under the impact of water flow and extends the service life. The reasonable laying density not only ensures sufficient purification capacity but also avoids the maintenance difficulties caused by overcrowding, thus effectively removing pollutants such as nitrogen and phosphorus in the tail water.

[0013] Preferably, the three-dimensional ecological floating bed includes iris and hydrocotyle vulgaris planted in the upper layer with a density of 9 clusters / m², and artificial aquatic plants suspended in the lower layer with a length of 1.2 - 1.8 m and an area ratio accounting for 1.2 - 1.8 times of the floating bed area.

[0014] By adopting the above technical solutions, the upper and lower layer structures of the three-dimensional ecological floating bed can effectively improve the water purification capacity. Iris and hydrocotyle vulgaris are planted in the upper layer with a density of 9 clusters per square meter. These plants have strong root absorption ability and growth and metabolism ability, can efficiently remove nitrogen and phosphorus nutrients in water, and beautify the water area landscape at the same time. Artificial aquatic plants are suspended in the lower layer with a length range of 1.2 - 1.8 m and an area accounting for 1.2 - 1.8 times of the total floating bed area. The artificial aquatic plants provide a large specific surface area, which is beneficial to the formation and growth of the microbial film, thus further strengthening the adsorption and degradation of organic matter and suspended particles. This combined design not only improves the pollutant removal efficiency but also enhances the stability and sustainability of the entire ecosystem.

[0015] Preferably, the pollution-tolerant plant purification zone includes hydrilla verticillata, myriophyllum spicatum, ceratophyllum demersum, and potamogeton crispus, arranged at a density of 72 plants per square meter.

[0016] By adopting the above technical solutions, the pollution-tolerant plant purification zone is composed of submerged plants such as hydrilla verticillata, myriophyllum spicatum, ceratophyllum demersum, and potamogeton crispus, and is arranged at a density of 72 plants per square meter. It can effectively absorb nitrogen and phosphorus nutrients in water, inhibit the overgrowth of algae, improve the water transparency, enhance the underwater light conditions, and thus achieve the efficient purification of the tail water.

[0017] Preferably, in step S4, submerged plants are arranged in the shallow water area of the ecological stabilization zone in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton malaianus = 5:3:2, and aquatic plants are arranged in the deep water area in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton malaianus = 2:4:4. The plant density of Vallisneria natans is 80 plants per square meter, and that of other plants is 50 plants per square meter. The coverage rate of submerged plants is ≥80%.

[0018] By adopting the above technical solution, the types and densities of submerged plants are reasonably configured according to different water depth areas in the ecological stabilization zone, ensuring the diversity and stability of the aquatic plant community. Specifically, the arrangement in the shallow water area in the ratio of Vallisneria natans, Potamogeton maackianus, and Potamogeton malaianus of 5:3:2 helps to give full play to the purification advantages of different plants and improve the absorption capacity of nutrients such as nitrogen and phosphorus in water; the arrangement in the deep water area in the ratio of Vallisneria natans, Potamogeton maackianus, and Potamogeton malaianus of 2:4:4 adapts to the characteristics of the deep water environment and enhances the fixation and transformation of pollutants in the bottom sediment by plant roots. At the same time, specifying the plant density of Vallisneria natans as 80 plants per square meter and that of other plants as 50 plants per square meter, and ensuring that the coverage rate of submerged plants is not less than 80% not only improves the purification efficiency of the tail water but also effectively prevents the competitive inhibition phenomenon caused by overcrowded plants, thus ensuring the long-term stable operation of the entire ecosystem and excellent landscape effects.

[0019] A tail water purification ecological treatment structure includes a composite ecological filter bed. The composite ecological filter bed includes a gravel layer, a filter material layer, and an emergent plant layer arranged from bottom to top. An aeration distribution pipe is buried in the gravel layer. An inlet channel and an outlet channel are respectively arranged on both sides of the composite ecological filter bed. One end of the aeration distribution pipe is communicated with the inlet channel so that the tail water in the inlet channel can flow into the composite ecological filter bed. An aeration system is externally connected to the aeration distribution pipe to be able to introduce air into the aeration distribution pipe. An overflow port is arranged on one side of the composite ecological filter bed so that the water in the composite ecological filter bed can flow into the outlet channel.

[0020] By adopting the above technical solution, the tail water is sequentially treated by the gravel layer, the filter material layer, and the emergent plant layer of the composite ecological filter bed, effectively realizing the synergistic effects of physical filtration, chemical adsorption, and biodegradation, and significantly reducing the nitrogen and phosphorus content in water. Among them, the design of the aeration distribution pipe ensures sufficient oxygen supply, promotes the activity of aerobic microorganisms, and improves the decomposition efficiency of organic matter; at the same time, the reasonable water flow organization and gas distribution help to form a stable biofilm environment and strengthen the nitrification and denitrification processes. Finally, this structure can stably output purified water that meets the Class III water quality standard of the Environmental Quality Standards for Surface Water, with both high efficiency and stability.

[0021] Preferably, the aeration water distribution pipe includes an inner pipe and an outer pipe. The end of the inner pipe forms a water inlet part communicating with the water inlet channel. The diameter of the connection end of the water inlet part and the water inlet channel is smaller than that of the connection end with the inner pipe. The port of the aeration system communicating with the inner pipe is located downstream of the water inlet part. A bending part is formed between one end of the inner pipe far from the water inlet part and the outer pipe. The tail water sequentially flows along the inner pipe and the bending part into the channel between the outer pipe and the inner pipe. The outer pipe is provided with water outlet holes so that the tail water can flow into the gravel layer.

[0022] By adopting the above technical solution, the special structural design of the aeration water distribution pipe effectively improves the mixing efficiency of the tail water and air. The setting of the bending part formed by the inner pipe and the outer pipe and the water outlet holes ensures that the tail water can fully contact with air before entering the gravel layer, thereby increasing the dissolved oxygen content in the water, which is beneficial to the growth and reproduction of subsequent microorganisms and the degradation of pollutants. At the same time, the unique diameter design of the water inlet part helps to control the flow rate of the tail water, avoids the situation that gas cannot be fully dissolved in the water due to too fast flow rate, and improves the treatment efficiency of the entire ecological filter bed.

[0023] Preferably, a guiding block is provided at the top of the inner wall of the inner pipe. A guiding surface is provided on one side of the guiding block facing the flowing direction of the tail water. The guiding surface can guide the bubbles and the tail water to move downward. The surface of the guiding block facing away from the flowing direction of the tail water is concave to form a groove to limit the contact between the rising bubbles and the guiding block.

[0024] By adopting the above technical solution, when the bubbles flow in the inner pipe along with the tail water, the bubbles are located at the top of the inner pipe. When the bubbles flow through the guiding block, the bubbles flow towards the bottom of the inner pipe under the guidance of the guiding surface. When the bubbles cross the guiding block, the bubbles rise to the top of the inner pipe in the tail water. During the rising process of the bubbles, the bubbles do not contact the guiding block, increasing the contact area between the bubbles and the tail water, improving the dissolution rate of the gas dissolved in the tail water, and being able to reduce the aeration flow rate while keeping the dissolved oxygen concentration in the tail water unchanged, reducing the energy consumption of the aeration system.

[0025] In summary, the present application includes at least the following beneficial technical effects: 1. There is no interference from fish in the solution of the present application. Relying on submerged plants (coverage rate ≥ 80%) and microbial communities to form a stable ecological barrier, the microorganism-plant cooperation directly denitrifies, and animals only assist in removing impurities without additional nitrogen load, thereby improving the stability of the purification system; 2. The porous structure of the filter material significantly increases the attachment area of microorganisms and forms a rich biofilm. The biofilm is naturally stratified inside, and the aerobic zone and the anoxic zone coexist, thereby realizing the synchronous nitrification and denitrification process, simplifying the process flow, reducing energy consumption and operating costs, and ensuring that the effluent quality meets the standards stably; 3. When the bubbles flow in the inner pipe along with the tail water, the bubbles are located at the top of the inner pipe. When the bubbles flow through the guiding block, the bubbles flow towards the bottom of the inner pipe under the guidance of the guiding surface. When the bubbles cross over the guiding block, the bubbles rise to the top of the inner pipe in the tail water. During the rising process of the bubbles, they do not come into contact with the guiding block, increasing the contact area between the bubbles and the tail water, enhancing the dissolution rate of the gas dissolved into the tail water, and being able to reduce the aeration flow rate while keeping the dissolved oxygen concentration in the tail water unchanged, thus reducing the energy consumption of the aeration system. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of an ecological treatment structure for tail water purification according to an embodiment of the present application.

[0027] Figure 2 is Figure 1 The enlarged view of part A in

[0028] Figure 3 is Figure 1 The enlarged view of part B in

[0029] Figure 4 It is a flowchart of an ecological treatment process for tail water purification according to an embodiment of the present application.

[0030] Description of the reference numerals: 1. Composite ecological filter bed; 11. Impermeable layer; 12. Gravel layer; 13. Filter media layer; 14. Emergent plant layer; 15. Aeration distribution pipe; 151. Inner pipe; 152. Outer pipe; 153. Inlet part; 154. Electromagnetic valve; 155. Plugging cover; 156. Bending part; 157. Outlet hole; 161. Guiding block; 162. Guiding surface; 163. Groove; 2. Outlet channel; 21. Overflow port; 3. Inlet channel; 4. Air pipe. Detailed Description of the Embodiment

[0031] The following Figures 1-4 further describes the present application in detail with reference to the attached

[0032] The inventors of the present application found that in the existing tail water purification process, there are problems such as the decline in denitrification efficiency due to the increase in ammonia nitrogen load caused by fish excrement, and at the same time, the death or over - reproduction of fish will lead to water quality deterioration and even system collapse. Therefore, the present application mainly adopts a tail water purification solution that does not require the introduction of fish and realizes stable and efficient tail water purification through multiple ecological treatment units, achieving the remarkable advantages of avoiding secondary pollution, improving the purification effect, and maintaining the long - term stability of the system.

[0033] An embodiment of the present application discloses an ecological treatment structure for tail water purification.

[0034] Refer to Figure 1A tailwater purification ecological treatment structure includes a composite ecological filter bed 1. This embodiment only shows two composite ecological filter beds 1. The composite ecological filter bed 1 can be transformed from a natural pond or artificially excavated. Each composite ecological filter bed 1 includes an impermeable layer 11, a gravel layer 12, a filter material layer 13, and an emergent plant layer 14 arranged from bottom to top. The impermeable layer 11 is a clay material, and a low permeability layer is formed by compacting the clay. The gravel layer 12 uses pebbles or multi-angular crushed stones with a particle size of 30-50mm as the base material, forming a certain gap between each other, and an aeration water distribution pipe 15 is buried in the gravel layer 12.

[0035] Reference Figure 1 An outlet channel 2 is provided between the two composite ecological filter beds 1. An inlet channel 3 is provided on the side of each composite ecological filter bed 1 facing away from the outlet channel 2. Each inlet channel 3 is used in conjunction with a water distribution channel. One end of the aeration water distribution pipe 15 is connected to the inlet channel 3, so that the tail water in the inlet channel 3 enters the composite ecological filter bed 1 through the aeration water distribution pipe 15, and then passes through the gap between the gravel layers 12 to achieve horizontal water distribution, so that the water surface of the tail water is more evenly raised. The porous filter material layer 13 is composed of volcanic rock, ceramsite or other natural mineral materials, and the weight per cubic meter is controlled within the range of 400kg to 600kg for easy handling and maintenance. The complex network space formed inside the filter material allows the dissolved oxygen concentration gradient to change, thereby supporting the coexistence and symbiosis of aerobic and anaerobic bacteria. For example: volcanic rock has good air permeability and a large specific surface area, which is very suitable for microbial attachment and growth.

[0036] Reference Figure 1 The emergent plant layer 14 can be selected from reeds, variegated reed, umbrella grass, pickerel grass, yellow iris, iris, aquatic canna, calamus, cattail, and lily of the valley according to the regional climate and geological landforms. An air pipe 4 is pre-buried in the filter material layer 13. The air pipe 4 and the aeration water pipe 15 are both externally connected to the aeration system. The aeration system mainly includes a fan and a pipeline. The fan is connected to the air pipe 4 and the aeration water pipe 15 through a pipeline, and air is passed into the air pipe 4 and the aeration water pipe 15 respectively. The setting of the air pipe 4 can provide oxygen for the emergent plants and prevent the emergent plants from rotting their roots.

[0037] Reference Figure 1 , Figure 2, on the dam on the side of the composite ecological filter bed 1 close to the water outlet channel 2, there is an overflow port 21. The overflow port 21 is at a certain height above the filter media layer 13. The aeration water distribution pipe 15 includes an inner pipe 151 and an outer pipe 152. The inner pipe 151 and the outer pipe 152 are coaxially arranged and fixedly connected to the dams on both sides of the composite ecological filter bed 1. One end of the inner pipe 151 is inserted into the water inlet channel 3. The end of the inner pipe 151 inserted into the water inlet channel 3 forms a water inlet part 153. The water inlet part 153 is a conical port, so that the caliber of the connection end of the water inlet part 153 and the water inlet channel 3 is smaller than the caliber of the connection end with the inner pipe 151. The pipeline of the aeration system is fixed at the end of the inner pipe 151 inserted into the water inlet channel 3, and the communication port with the inner pipe 151 is located downstream of the water inlet part 153. Since the caliber of the inlet end of the water inlet part 153 is smaller than that of the other end, the water pressure at the inlet end of the water inlet part 153 is greater than that of the other end, thus effectively preventing the bubbles in the tail water from entering the water inlet channel 3. The unique caliber design of the water inlet part 153 helps to control the flow rate of the tail water, avoid the situation that the gas cannot be fully dissolved in the water due to too fast flow rate, and improve the treatment efficiency of the entire ecological filter bed.

[0038] Refer to Figure 1 , Figure 2 , an electromagnetic valve 154 is provided at the front end of the water inlet part 153 to control the opening and closing of the water inlet part 153. When the tail water in the composite ecological filter bed 1 accumulates to the specified height, the electromagnetic valve 154 is closed. When the purification of the tail water in the composite ecological filter bed 1 is completed, the electromagnetic valve 154 is opened, and the tail water in the water inlet channel 3 enters the composite ecological filter bed 1, raising the liquid level of the purified tail water, and then flowing the purified tail water into the water outlet channel 2 from the overflow port 21 to realize the outlet of the purified tail water.

[0039] Refer to Figure 1 , Figure 3 , the end of the inner pipe 151 away from the water inlet part 153 is communicated with the water outlet channel 2, and a sealing cover 155 is equipped at this end, which is normally closed. When it is necessary to drain all the tail water in the composite ecological filter bed 1 at one time, the sealing cover 155 is opened so that all the tail water is drained into the water outlet channel 2. The inner pipe 151 is provided with through holes at the end away from the water inlet part 153. The arrangement of the through holes forms a bending part 156. At this time, the tail water enters the inner pipe 151 from the water inlet part 153, flows along the inner pipe 151 to the bending part 156, and then flows into the channel between the inner pipe 151 and the outer pipe 152. A plurality of water outlet holes 157 are opened on the outer pipe 152. The plurality of water outlet holes 157 are arranged at intervals along the length direction of the outer pipe 152. The tail water in the channel between the inner pipe 151 and the outer pipe 152 flows into the gravel layer 12 through the water outlet holes 157, increasing the uniformity of the tail water distribution in the composite ecological filter bed 1.

[0040] The bent portion 156 formed by the inner pipe 151 and the outer pipe 152 and the arrangement of the water outlet holes 157 ensure that the tail water can fully contact with the air before entering the gravel layer 12, thereby enhancing the dissolved oxygen content in the water, which is beneficial to the growth and reproduction of subsequent microorganisms and the degradation of pollutants.

[0041] Refer to Figure 1 、 Figure 2 On the top of the inner wall of the inner pipe 151, a plurality of guiding blocks 161 are provided. The plurality of guiding blocks 161 are arranged at intervals along the length of the inner pipe 151. On the side of the guiding block 161 facing the flowing direction of the tail water, a guiding surface 162 is provided. The guiding surface 162 is inclined towards the bottom of the inner pipe 151 along the water flow direction, so that the guiding surface 162 guides the tail water and the bubbles to flow towards the bottom of the inner pipe 151. The side of the guiding block 161 facing away from the flowing direction of the tail water is concave to form a groove 163. The arrangement of the guiding surface 162 and the groove 163 makes the cross-section of the guiding block 161 in the shape of a dovetail, and a tip is formed at the connection between the guiding surface 162 and the groove wall of the groove 163. When the bubble crosses the guiding surface 162, the bubble rises along the water flow direction towards the top of the inner pipe 151. During the rising process of the bubble, the bubble does not contact the guiding block 161. Every time the bubble passes through a guiding block 161, the bubble descends and then rises. During this process, the bubble contacts the tail water, increasing the contact area between the bubble and the tail water and improving the dissolution rate of the gas dissolved in the tail water. It can reduce the aeration flow rate and the energy consumption of the aeration system while keeping the dissolved oxygen concentration in the tail water unchanged.

[0042] The implementation principle of an ecological treatment structure for tail water purification in an embodiment of the present application is as follows: When discharging the tail water into the composite ecological filter bed 1, the electromagnetic valve 154 is opened, and the tail water in the water inlet channel 3 enters the inner pipe 151, and then enters the gravel layer 12 along the inner pipe 151 and the outer pipe 152, and rises along the gravel layer 12 and the filter material layer 13 to the emergent plant layer 14 and is located below the overflow port 21. On the other hand, the aeration system injects air into the inner pipe 151, and the air forms bubbles in the inner pipe 151 and moves along the water flow direction at the top of the inner pipe 151. When the bubble passes through the guiding block 161, the guiding surface 162 guides the tail water and the bubble to flow towards the bottom of the inner pipe 151. When the bubble crosses the guiding surface 162, the bubble rises along the water flow direction towards the top of the inner pipe 151. During the rising process of the bubble, the bubble does not contact the guiding block 161. Every time the bubble passes through a guiding block 161, the bubble descends and then rises. During this process, the bubble contacts the tail water, increasing the contact area between the bubble and the tail water and improving the dissolution rate of the gas dissolved in the tail water. It can reduce the aeration flow rate and the energy consumption of the aeration system while keeping the dissolved oxygen concentration in the tail water unchanged.

[0043] After the purification of the tail water in the composite ecological filter bed 1 is completed, the electromagnetic valve 154 is opened, and the tail water in the water inlet channel 3 enters the composite ecological filter bed 1, raising the liquid level of the purified tail water, and then flowing the purified tail water into the water outlet channel 2 from the overflow port 21 to achieve the effluent of the purified tail water.

[0044] An embodiment of the present application discloses an ecological treatment process for tail water purification.

[0045] Refer to Figure 4 , an ecological treatment process for tail water purification, comprising the following steps: S1. Treatment in the ecological strengthening area: The tail water is introduced into the ecological strengthening area, and the tail water is preliminarily purified by passing through the composite ecological filter bed 1, the artificial aquatic plant purification zone, the three-dimensional ecological floating bed, and the pollution-tolerant plant purification zone in sequence, and the TN after purification is ≤ 4 mg / L.

[0046] The composite ecological filter bed 1 includes a gravel bed, filter media, emergent plants, and an aeration pipe. Among them, the gravel layer 12 selects cobblestones or multi-angular crushed stones with a particle size of 30 - 50 mm as the basic material, forming certain voids with each other. An aeration pipe is buried in the gravel layer 12, and the aeration intensity of the aeration pipe is 18 - 22 L / (m²·s). The setting of this aeration intensity promotes the metabolic activities of aerobic microorganisms, improves the nitrification efficiency, and finally achieves the effect of efficient nitrogen and phosphorus removal.

[0047] The filter media is composed of porous volcanic rock, ceramsite, or other natural mineral materials, and the weight per cubic meter is controlled within the range of 400 kg to 600 kg for easy handling and maintenance. The porous structure of the filter media significantly increases the microbial attachment area and forms a rich biofilm. The biofilm is naturally stratified inside, with an aerobic zone and an anoxic zone coexisting, thus realizing the synchronous nitrification and denitrification process. This design effectively improves the nitrogen removal efficiency, simplifies the process flow, reduces energy consumption and operating costs, and ensures that the effluent quality meets the standards stably.

[0048] The emergent plants can be selected according to the regional climate, geology, and landform, such as reed, variegated giant reed, umbrella grass, pickerelweed, yellow iris, iris ensata, water canna, calamus, cattail, and thalia dealbata.

[0049] In the artificial aquatic plant purification zone, biological affinity materials are selected as the carriers of artificial aquatic plants, such as modified bamboo fibers and natural plant fibers (such as coconut shell fibers), which can promote the attachment of microorganisms. The artificial aquatic plants are designed in a three-dimensional grid shape, such as brush-shaped or honeycomb-shaped, to increase the amount of microbial attachment and the oxygen exchange efficiency. The artificial aquatic plants are fixed to the bottom of the pool by heavy objects (concrete blocks, stones) or steel bars, and the spacing is adjusted according to the water flow velocity and the water pollution load, with an interval of 20-50 cm. In the initial stage, activated sludge or high-efficiency strains (such as nitrifying bacteria and denitrifying bacteria) are added to accelerate the formation of biofilms, and carbon sources (such as glucose) or trace elements are supplemented to optimize the microbial metabolic environment. The water flow is controlled to slowly pass through the artificial aquatic plant zone through a guide plate or a water pump to extend the hydraulic retention time.

[0050] The specific surface area of the artificial aquatic plants ≥ 250 m² / m². The artificial aquatic plants in the artificial aquatic plant purification zone have a large specific surface area, which can effectively adsorb pollutants in the water and improve the purification efficiency; the tensile strength ≥ 10 KN / m. The high tensile strength ensures the stability of the artificial aquatic plants under the impact of water flow and extends the service life; the laying density is 8-12 plants / m². The reasonable laying density not only ensures sufficient purification capacity but also avoids the maintenance difficulties caused by overcrowding, thus effectively removing pollutants such as nitrogen and phosphorus in the tail water.

[0051] The floating bed frame of the three-dimensional ecological floating bed uses lightweight, corrosion-resistant and environmentally friendly materials, such as PVC pipes, bamboo, recycled plastics or foam boards. A mesh structure (nylon mesh or metal mesh) is installed at the bottom of the frame to carry the substrate and plants while keeping the water flow smooth. Porous lightweight materials such as ceramsite, biochar, coconut shell fibers or synthetic fibers are selected as the substrate filling. The substrate is packed into a permeable mesh bag and evenly laid in the frame grid or fixed to the bottom of the frame with ropes to prevent loss. Iris and Hydrocotyle vulgaris are planted in the upper layer of the three-dimensional ecological floating bed at a density of 9 clusters / m². Iris and Hydrocotyle vulgaris have strong root absorption ability and growth and metabolic ability, which can efficiently remove nitrogen and phosphorus nutrients in the water and beautify the water area landscape at the same time. Artificial aquatic plants are suspended in the lower layer, with a length of 1.2-1.8 m and an area ratio of 1.2-1.8 times that of the floating bed area. The artificial aquatic plants provide a large specific surface area, which is conducive to the formation and growth of microbial films, thus further strengthening the adsorption and degradation of organic matter and suspended particles.

[0052] The pollution-tolerant plant purification zone consists of submerged plants such as Hydrilla verticillata, Myriophyllum spicatum, Ceratophyllum demersum and Potamogeton crispus, arranged at 72 plants per square meter, which can effectively absorb nitrogen and phosphorus nutrients in the water, inhibit the overgrowth of algae, improve the water transparency and enhance the underwater light conditions, thus achieving the efficient purification of the tail water.

[0053] S2. Ecological buffer treatment: The effluent from the ecological enhancement area is introduced into the ecological buffer, and the submerged plants in the ecological buffer are used to secondary purify the tail water, with the TN in the purified water ≤ 3 mg / L.

[0054] In the ecological buffer, submerged plants are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Ceratophyllum demersum: Potamogeton wrightii: Potamogeton pectinatus = 6:1:1:1:1. In the waterfront zone, especially in areas with good hydrophilicity, submerged plants mainly composed of Vallisneria natans are arranged. The ecological buffer secondary purifies the tail water through the reasonably proportioned submerged plants, effectively removing residual organic matter and nitrogen and phosphorus nutrients.

[0055] S3. Ecological display area treatment: While ensuring the purification effect to the greatest extent, the ecological display area enhances the landscape effect of the water body. In the shallow water area of the ecological display area, plants are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus = 8:1:1, and in the deep water area, they are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus = 1:6:3. The tail water treated by the ecological buffer is introduced into the ecological display area to tertiary purify the tail water, with the TN in the purified tail water ≤ 2 mg / L.

[0056] S4. Ecological stabilization area treatment: Submerged plants, floating-leaved plants, and emergent plants are arranged in the ecological stabilization area to construct an aquatic plant community, and then zooplankton, benthic animals, and microorganisms are put in to optimize the community. The tail water treated by the ecological display area is introduced into the ecological stabilization area to quaternary purify the tail water, with the TN in the purified tail water ≤ 1.5 mg / L, and the effluent quality stably reaches the Class III water quality standard of "Surface Water Environment Quality Standard" (GB3838 - 2002) (TN ≤ 1.5 mg / L).

[0057] In the shallow water area of the ecological stabilization area, submerged plants are arranged in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton wrightii = 5:3:2, and in the deep water area, aquatic plants are arranged in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton wrightii = 2:4:4, which helps to give full play to the purification advantages of different plants and improve the absorption capacity of nutrients such as nitrogen and phosphorus in water; the plant density of Vallisneria natans is 80 plants per square meter, and that of other plants is 50 plants per square meter, and the coverage rate of submerged plants ≥ 80%, which not only improves the tail water purification efficiency but also effectively prevents the competitive inhibition phenomenon caused by excessive plant density, thus ensuring the long-term stable operation of the entire ecosystem and excellent landscape effect.

[0058] The floating-leaved plant Nymphaea tetragona is selected, and the emergent plants can be selected according to the regional climate, geology and landform, such as Phragmites australis, Arundo donax var. versicolor, Cyperus alternifolius, Pontederia cordata, Iris wilsonii, Iris ensata var. hortensis, Canna glauca, Acorus calamus, Typha orientalis, Thalia dealbata, etc.

[0059] The zooplankton are cladocerans, such as water fleas and daphnia, which are used to feed on algae and suspended particles. The benthic animals are mollusks and crustaceans, such as river mussels, snails, and freshwater mussels, which filter and feed on suspended matter and algae; gammarids, which decompose the organic matter in the bottom mud; and caridina and mysids, which feed on organic debris and algae.

[0060] The above are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. An ecological treatment process for tail water purification, characterized in that: It includes the following steps: S1. Treatment in the ecological enhancement area: The tail water is introduced into the ecological enhancement area, and the tail water is preliminarily purified by passing through a composite ecological filter bed (1), an artificial waterweed purification zone, a three-dimensional ecological floating bed, and a pollution-tolerant plant purification zone in sequence; S2. Treatment in the ecological buffer zone: The effluent from the ecological enhancement area is introduced into the ecological buffer zone, and the tail water is secondarily purified by submerged plants in the ecological buffer zone. The submerged plants are planted in the ratio of Vallisneria natans: Potamogeton maackianus: Ceratophyllum demersum: Potamogeton wrightii: Potamogeton pectinatus = 6:1:1:1:1; S3. Treatment in the ecological display area: In the shallow water area of the ecological display area, Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus are planted in the ratio of 8:1:1, and in the deep water area, Vallisneria natans: Potamogeton maackianus: Potamogeton pectinatus are planted in the ratio of 1:6:

3. The tail water after treatment in the ecological buffer zone is introduced into the ecological display area for tertiary purification of the tail water; S4. Treatment in the ecological stabilization area: Submerged plants, floating-leaved plants, and emergent plants are arranged in the ecological stabilization area to construct an aquatic plant community, and then zooplankton, benthic animals, and microorganisms are put in to optimize the community. The tail water after treatment in the ecological display area is introduced into the ecological stabilization area for quaternary purification of the tail water.

2. The ecological treatment process for tail water purification according to claim 1, characterized in that: The composite ecological filter bed (1) includes a gravel bed, filter media, emergent plants, and an aeration pipe, and denitrifies and removes phosphorus through the synergistic action of physical filtration, chemical adsorption, and biofilm, where: The sewage residence time is 1.3 - 1.7 hours; The porosity of the filter media is 70% - 75%; The filtration rate is 0.5 - 0.7 m / h; The aeration intensity is 18 - 22 L / (m²·s).

3. The tail water purification ecological treatment process according to claim 2, characterized in that: The filter media has a porous structure so that microorganisms can adhere to the filter media and form aerobic zones and anoxic zones. Microorganisms carry out nitrification reactions in the aerobic zones and denitrification reactions in the anaerobic zones.

4. The tail water purification ecological treatment process according to claim 1, characterized in that: In the artificial waterweed purification zone, the specific surface area of the artificial waterweed is ≥250 m² / m², the tensile strength is ≥10 KN / m, and the laying density is 8 - 12 plants / m².

5. The ecological treatment process for tail water purification according to claim 1, characterized in that: The three-dimensional ecological floating bed includes Iris tectorum and Hydrocotyle vulgaris planted in the upper layer with a density of 9 clusters / m², and artificial waterweeds are suspended in the lower layer with a length of 1.2 - 1.8 m and an area ratio that is 1.2 - 1.8 times the area of the floating bed.

6. The ecological treatment process for tail water purification according to claim 1, characterized in that: The pollution-tolerant plant purification zone includes Hydrilla verticillata, Myriophyllum spicatum, Ceratophyllum demersum, and Potamogeton crispus, and is arranged at 72 plants per square meter.

7. The tail water purification ecological treatment process according to claim 1, characterized in that: In step S4, in the shallow water area of the ecological stabilization area, submerged plants are arranged in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton wrightii = 5:3:2, and in the deep water area, aquatic plants are arranged in the ratio of Vallisneria natans: Potamogeton maackianus: Potamogeton wrightii = 2:4:

4. The plant density of Vallisneria natans is 80 plants per square meter, and that of other plants is 50 plants per square meter. The coverage rate of submerged plants is ≥80%.

8. An ecological treatment structure for tail water purification, using the ecological treatment process for tail water purification described in any one of claims 1-7, characterized in that: It includes a composite ecological filter bed (1), and the composite ecological filter bed (1) includes a gravel layer (12), a filter media layer (13), and an emergent plant layer (14) arranged from bottom to top. An aeration water distribution pipe (15) is buried in the gravel layer (12). An inlet channel (3) and an outlet channel (2) are respectively arranged on both sides of the composite ecological filter bed (1). One end of the aeration water distribution pipe (15) is communicated with the inlet channel (3) so that the tail water in the inlet channel (3) can flow into the composite ecological filter bed (1). An aeration system is externally connected to the aeration water distribution pipe (15) so that air can be introduced into the aeration water distribution pipe (15). An overflow port (21) is arranged on one side of the composite ecological filter bed (1) so that the water in the composite ecological filter bed (1) can flow into the outlet channel (2).

9. The tail water purification ecological treatment structure according to claim 8, characterized in that: The aeration water distribution pipe (15) includes an inner pipe (151) and an outer pipe (152). An inlet part (153) communicated with the inlet channel (3) is formed at the end of the inner pipe (151). The diameter of the connection end of the inlet part (153) and the inlet channel (3) is smaller than the diameter of the connection end with the inner pipe (151). The port of the aeration system communicated with the inner pipe (151) is located downstream of the inlet part (153). A bending part (156) is formed between one end of the inner pipe (151) far from the inlet part (153) and the outer pipe (152). The tail water sequentially flows along the inner pipe (151) and the bending part (156) into the channel between the outer pipe (152) and the inner pipe (151). The outer pipe (152) is provided with water outlet holes (157) so that the tail water can flow into the gravel layer (12).

10. The tail water purification ecological treatment structure according to claim 9, characterized in that: A guiding block (161) is arranged at the top of the inner wall of the inner pipe (151). A guiding surface (162) is arranged on the side of the guiding block (161) facing the flowing direction of the tail water. The guiding surface (162) can guide the bubbles and the tail water to move downward. A groove (163) is formed in a concave shape on the side of the guiding block (161) facing away from the flowing direction of the tail water to limit the contact between the rising bubbles and the guiding block (161).

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