A coastal saline-alkali land salt discharge tail water self-adaptive ecological purification system and method

Abstract

This invention discloses an adaptive ecological purification system and method for saline wastewater discharge from coastal saline-alkali land, relating to the field of constructed wetlands. The system includes a storage unit, a first intelligent monitoring and diversion unit, a first-stage ecological treatment unit, a second-stage ecological treatment unit, and a control unit. The first and second-stage ecological treatment units are respectively equipped with salt-tolerant plant communities with high and low salinity tolerance thresholds. Each unit's inner wall is provided with an impermeable isolation layer. The first intelligent monitoring and diversion unit monitors the salinity of the discharge wastewater in real time and transmits the data to the control unit. When the salinity exceeds a preset threshold, the wastewater is diverted to the first-stage ecological treatment unit where highly salt-tolerant pioneer plants resist high osmotic pressure stress. When the salinity is below the preset threshold, the wastewater is diverted to the second-stage ecological treatment unit for conventional nitrogen and phosphorus removal. This system and method solve the problems of poor habitat adaptability and significant decline in purification efficiency under extreme salt stress in traditional wetlands, and also address the problem of secondary salinization of surrounding soils.

Description

Technical Field

[0001] This invention relates to the field of constructed wetlands, and in particular to an adaptive ecological purification system and method for saline tailwater discharge from coastal saline-alkali land. Background Technology

[0002] In recent years, engineering technologies such as underground pipe salt discharge and open ditch salt discharge have been widely promoted in coastal areas. However, the wastewater generated during the improvement of saline-alkali land has two characteristics: firstly, high and fluctuating salinity (TDS typically fluctuates between 2g / L and 30g / L); and secondly, it carries large amounts of nutrients such as nitrogen and phosphorus from farmland. If high-salinity, eutrophic wastewater is discharged directly into receiving water bodies without treatment, it will cause serious stress to the coastal aquatic environment. Constructed wetlands, as a conventional ecological technology for treating agricultural non-point source pollution, have the advantages of balancing ecological considerations and low cost. However, when directly applied to the treatment of coastal wastewater discharge, they face significant technical bottlenecks and have the following drawbacks: (1) Habitat mismatch leads to a significant decline in purification efficiency. Existing constructed wetlands generally use conventional salt-tolerant plants such as reeds and cattails, whose salt tolerance limit is generally no more than 10-15 g / L. The salinity of coastal salt discharge tailwater fluctuates drastically due to meteorological and agricultural factors (it is very easy to exceed 20 g / L in the dry season), far exceeding the osmotic regulation capacity of conventional plants. The high osmotic pressure environment formed by high salt easily causes plant cells to lose water, leading to plant community degradation. At the same time, the high salt environment (TDS>10 g / L) will significantly inhibit the enzyme activity of nitrifying / denitrifying bacteria, causing the biological nitrogen and phosphorus removal system to almost fail under extreme salt stress.

[0003] (2) Lack of systematic seepage prevention leads to the infiltration of high-salinity tailwater, causing secondary salinization of the surrounding soil. The groundwater level in coastal plains is generally shallow. In order to ensure the hydraulic retention time (HRT) and treatment load of water purification, traditional constructed wetlands often maintain a high operating water level, resulting in a reverse hydraulic pressure difference between the water and the groundwater layer of the surrounding farmland. Such pressure difference is difficult to avoid in shallow coastal groundwater areas, and existing constructed wetlands generally lack systematic seepage prevention design. As a result, high-concentration salt water is backflowed and infiltrated through the soil channels under the pressure difference, which aggravates the risk of salt return to the surrounding soil and seriously weakens the overall benefits of salt drainage and improvement projects. Summary of the Invention

[0004] To address the above technical problems, this invention provides an adaptive ecological purification system and method for wastewater discharge from coastal saline-alkali land. This system solves the problems of poor adaptability to traditional wetland habitats and significant decline in purification efficiency under extreme salt stress, and also solves the problem of secondary salinization of surrounding soils induced by the operation of the ecological purification system.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides an adaptive ecological purification system for wastewater discharge from coastal saline-alkali land, comprising a storage unit, a first intelligent monitoring and diversion unit, a first-stage ecological treatment unit, a second-stage ecological treatment unit, and a control unit. The storage unit receives and stores wastewater from the coastal saline-alkali land. The outlet of the storage unit is connected to the first intelligent monitoring and diversion unit, which is connected to both the inlet of the first-stage ecological treatment unit and the inlet of the second-stage ecological treatment unit. All three units have an impermeable isolation layer on their inner walls. The first-stage ecological treatment unit contains a first salt-tolerant plant community, and the second-stage ecological treatment unit contains a second salt-tolerant plant community. The first salt-tolerant plant community has a salinity tolerance threshold greater than that of the first-stage ecological treatment unit. The second salt-tolerant plant community's salinity tolerance threshold; the first intelligent monitoring diversion unit is electrically connected to the control unit, the first intelligent monitoring diversion unit is used to monitor a first real-time salinity parameter and transmit it to the control unit, the control unit is used to compare the first real-time salinity parameter with a first preset salinity threshold, and control the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit or the inlet of the second-level ecological treatment unit, wherein, when the first real-time salinity parameter is greater than the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the second-level ecological treatment unit.

[0006] Preferably, the first intelligent monitoring and diversion unit includes a first outlet pipe, a first branch pipe, a second branch pipe, a first salinity monitoring component, a first delivery pump, and a first three-way valve. One end of the first outlet pipe is connected to the outlet of the storage unit, and the other end of the first outlet pipe is sequentially connected to the first salinity monitoring component, the first delivery pump, and the first three-way valve. The first outlet and the second outlet of the first three-way valve are respectively connected to the first branch pipe and the second branch pipe. The end of the first branch pipe away from the first three-way valve is connected to the inlet of the first-stage ecological treatment unit, and the end of the second branch pipe away from the first three-way valve is connected to the inlet of the second-stage ecological treatment unit. The first salinity monitoring component, the first delivery pump, and the first three-way valve are all electrically connected to the control unit.

[0007] Preferably, the system further includes a second intelligent monitoring and diversion unit. The outlet of the first-stage ecological treatment unit is connected to the second intelligent monitoring and diversion unit. The second intelligent monitoring and diversion unit is connected to both the return port of the first-stage ecological treatment unit and the inlet of the second-stage ecological treatment unit. The second intelligent monitoring and diversion unit is electrically connected to the control unit. The second intelligent monitoring and diversion unit is used to monitor a second real-time salinity parameter and transmit it to the control unit. The control unit is used to compare the second real-time salinity parameter with a second preset salinity threshold and control the second intelligent monitoring and diversion unit to connect with either the return port of the first-stage ecological treatment unit or the inlet of the second-stage ecological treatment unit. Specifically, when the second real-time salinity parameter is greater than the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the return port of the first-stage ecological treatment unit; when the second real-time salinity parameter is less than or equal to the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the inlet of the second-stage ecological treatment unit.

[0008] Preferably, the second intelligent monitoring and diversion unit includes a second outlet pipe, a third branch pipe, a fourth branch pipe, a second salinity monitoring component, a second delivery pump, and a second three-way valve. One end of the second outlet pipe is connected to the outlet of the first-stage ecological treatment unit, and the other end of the second outlet pipe is sequentially connected to the second salinity monitoring component, the second delivery pump, and the second three-way valve. The first outlet and the second outlet of the second three-way valve are respectively connected to the third branch pipe and the fourth branch pipe. The end of the third branch pipe away from the second three-way valve is connected to the return port of the first-stage ecological treatment unit, and the end of the fourth branch pipe away from the second three-way valve is connected to the inlet of the second-stage ecological treatment unit. The second salinity monitoring component, the second delivery pump, and the second three-way valve are all electrically connected to the control unit.

[0009] Preferably, a first inlet valve and a first outlet valve are respectively provided at the inlet and outlet of the first-stage ecological treatment unit, and a first depth monitoring component is provided in the first-stage ecological treatment unit. The first inlet valve, the first outlet valve and the first depth monitoring component are all electrically connected to the control unit.

[0010] Preferably, a second inlet valve and a second outlet valve are respectively provided at the inlet and outlet of the second-stage ecological treatment unit, and a second depth monitoring component is provided in the second-stage ecological treatment unit. The second inlet valve, the second outlet valve and the second depth monitoring component are all electrically connected to the control unit.

[0011] Preferably, the first salt-tolerant plant community is Salicornia glutinosa and / or Suaeda salsa.

[0012] Preferably, the second salt-tolerant plant community includes a highly salt-tolerant zone plant community, a transition zone plant community, and a deep purification zone plant community arranged sequentially from the inlet near the second-level ecological treatment unit to the outlet near the second-level ecological treatment unit. The highly salt-tolerant zone plant community uses reeds, the transition zone plant community uses tamarisk, and the deep purification zone plant community uses calamus and / or canna lily.

[0013] Preferably, the impermeable barrier layer is a composite geomembrane or a compacted clay layer, and the permeability coefficient of the impermeable barrier layer is not greater than 1×10⁻⁶. -7 cm / s.

[0014] This invention also provides a purification method based on an adaptive ecological purification system for saline wastewater discharge from coastal saline-alkali land, comprising the following steps: Step 1: The tailwater from the coastal saline-alkali land is collected into the storage unit, and the salinity parameters of the water effluent from the storage unit are monitored in real time through the first intelligent monitoring and diversion unit to obtain the first real-time salinity parameter. Step 2: Based on the comparison result of the first real-time salinity parameter and the first preset salinity threshold, the control unit automatically controls the first intelligent monitoring diversion unit to perform dynamic switching of the hydraulic path: when the first real-time salinity parameter is greater than the first preset salinity threshold, the effluent is introduced into the first-level ecological treatment unit; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the effluent is introduced into the second-level ecological treatment unit.

[0015] The present invention achieves the following technical effects compared to the prior art: This invention introduces a first intelligent monitoring and diversion unit based on a first real-time salinity parameter. During low-salinity periods, the system automatically diverts the effluent to the second-stage ecological treatment unit, i.e., the conventional salt-tolerant main treatment unit. When the influent exhibits high-salinity characteristics, the system automatically switches to the first-stage ecological treatment unit, i.e., the extreme salt-tolerant pioneer unit. The first-stage ecological treatment unit utilizes the high osmotic pressure characteristics of the first salt-tolerant plant community with a high salinity tolerance threshold to resist physiological dehydration caused by external high osmotic pressure, enabling it to adapt to high-salinity stress environments and improve purification stability under high-salinity conditions. This avoids the vegetation withering and community degradation problems that occur in traditional wetland single salt-tolerant vegetation systems under high-salinity impacts during the dry season. At the same time, it significantly alleviates the inhibitory effect of high-salinity environments on the activity of nitrifying and denitrifying microbial enzymes, ensuring that the system continuously and stably achieves nitrogen removal, phosphorus removal, and salt reduction under alternating high and low salinity conditions. This solves the problems of poor habitat adaptability and significant decline in purification efficiency under extreme salt stress in traditional wetlands.

[0016] In this invention, an impermeable isolation layer is deployed throughout the storage unit, the first-stage ecological treatment unit, and the second-stage ecological treatment unit. This effectively isolates the high-salinity water body inside the unit from the hydraulic connection with the groundwater of the surrounding farmland. Even if there is a reverse hydraulic pressure difference due to maintaining a high operating water level, the high-salinity tailwater cannot seep back into or flow back into the surrounding soil through the soil channels. This solves the problem of secondary salinization of the surrounding soil induced by the operation of the ecological purification system, ensures that the treatment effect of the underground pipe and open ditch salt drainage improvement project in coastal saline-alkali land does not rebound, and improves the stability, adaptability, and engineering application value of the treatment of salt tailwater in coastal areas. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the adaptive ecological purification system for salt discharge tailwater from coastal saline-alkali land provided by the present invention; Figure 2 This is a schematic diagram of the structure of the second-stage ecological treatment unit in the adaptive ecological purification system for salt discharge tailwater from coastal saline-alkali land provided by the present invention.

[0019] Explanation of reference numerals in the attached diagram: 1. Storage unit; 2. First-stage ecological treatment unit; 3. Second-stage ecological treatment unit; 4. First outlet pipe; 5. First salinity monitoring component; 6. First transfer pump; 7. First three-way valve; 8. First branch pipe; 9. Second branch pipe; 10. Second outlet pipe; 11. Second salinity monitoring component; 12. Second transfer pump; 13. Second three-way valve; 14. Third branch pipe; 15. Fourth branch pipe; 16. First depth monitoring component; 17. Second depth monitoring component; 18. First salt-tolerant plant community; 19. Plant community in the highly salt-tolerant zone; 20. Plant community in the transition zone; 21. Plant community in the deep purification zone. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide an adaptive ecological purification system and method for salt discharge tailwater from coastal saline-alkali land, which solves the problems of poor adaptability of traditional wetland habitats and significant decline in purification efficiency under extreme salt stress, and solves the problem of secondary salinization of surrounding soil induced by the operation of the ecological purification system.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figures 1-2 As shown, this embodiment provides an adaptive ecological purification system for wastewater discharge from coastal saline-alkali land, including a storage unit 1, a first intelligent monitoring and diversion unit, a first-stage ecological treatment unit 2, a second-stage ecological treatment unit 3, and a control unit. The storage unit 1 receives and stores wastewater discharge from the coastal saline-alkali land. The outlet of the storage unit 1 is connected to the first intelligent monitoring and diversion unit, which is connected to the inlet of the first-stage ecological treatment unit 2 and the inlet of the second-stage ecological treatment unit 3. All three units—storage unit 1, first-stage ecological treatment unit 2, and second-stage ecological treatment unit 3—are equipped with impermeable isolation layers on their inner walls. The first-stage ecological treatment unit 2 contains a first salt-tolerant plant community 18, and the second-stage ecological treatment unit 3 contains a second salt-tolerant plant community. The first intelligent monitoring diversion unit is electrically connected to the control unit. The first intelligent monitoring diversion unit is used to monitor the first real-time salinity parameter and transmit it to the control unit. The control unit is used to compare the first real-time salinity parameter with the first preset salinity threshold and control the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit 2 or the inlet of the second-level ecological treatment unit 3. When the first real-time salinity parameter is greater than the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit 2. When the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the second-level ecological treatment unit 3.

[0024] This embodiment introduces a first intelligent monitoring and diversion unit based on a first real-time salinity parameter. During low-salinity periods, the system automatically switches the effluent to the second-stage ecological treatment unit 3, which is a conventional salt-tolerant main treatment unit. When the influent exhibits high-salinity characteristics, the system automatically switches to the first-stage ecological treatment unit 2, which is an extreme salt-tolerant pioneer treatment unit. The first-level ecological treatment unit 2 utilizes the high osmotic pressure of the first salt-tolerant plant community 18, which has a high salt tolerance threshold, to resist physiological dehydration caused by external high osmotic pressure. Under extreme high salt stress, it maintains biological interception and enrichment salt reduction functions, enabling it to adapt to high salt stress environments and improve purification stability under high salt conditions. This avoids the problems of vegetation withering and community degradation that occur in traditional wetland single salt-tolerant vegetation systems under the impact of high salt in the dry season. At the same time, it significantly alleviates the inhibitory effect of high salt environment on the activity of nitrification and denitrification microbial enzymes, ensuring that the system can continuously and stably achieve nitrogen removal, phosphorus removal and salt reduction under alternating high and low salt conditions. This solves the problems of poor habitat adaptability and significant decline in purification efficiency under extreme salt stress in traditional wetlands.

[0025] In this embodiment, an impermeable isolation layer is deployed throughout the storage unit 1, the first-level ecological treatment unit 2, and the second-level ecological treatment unit 3. This effectively isolates the high-salinity water body inside the unit from the hydraulic connection with the groundwater of the surrounding farmland. Even if there is a reverse hydraulic pressure difference due to maintaining a high operating water level, the high-salinity tailwater cannot seep back into or flow back into the surrounding soil through the soil channel. This solves the problem of secondary salinization of the surrounding soil induced by the operation of the ecological purification system, ensures that the treatment effect of the coastal saline-alkali land underground pipe and open ditch salt drainage improvement project does not rebound, and improves the stability, adaptability, and engineering application value of the treatment of salt drainage tailwater in the coastal area.

[0026] Specifically, the first intelligent monitoring and diversion unit includes a first outlet pipe 4, a first branch pipe 8, a second branch pipe 9, a first salinity monitoring component 5, a first delivery pump 6, and a first three-way valve 7. One end of the first outlet pipe 4 is connected to the outlet of the storage unit 1, and the other end of the first outlet pipe 4 is sequentially connected to the first salinity monitoring component 5, the first delivery pump 6, and the first three-way valve 7. The first outlet and the second outlet of the first three-way valve 7 are respectively connected to the first branch pipe 8 and the second branch pipe 9. The end of the first branch pipe 8 away from the first three-way valve 7 is connected to the inlet of the first-stage ecological treatment unit 2, and the end of the second branch pipe 9 away from the first three-way valve 7 is connected to the inlet of the second-stage ecological treatment unit 3. The first salinity monitoring component 5, the first delivery pump 6, and the first three-way valve 7 are all electrically connected to the control unit.

[0027] During operation, when the first real-time salinity parameter is greater than the first preset salinity threshold, the control unit controls the first three-way valve 7 to connect the first outlet pipe 4, the first branch pipe 8, and the first-stage ecological treatment unit 2 in sequence, so as to introduce the salt discharge tailwater into the first-stage ecological treatment unit 2; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the control unit controls the first three-way valve 7 to connect the first outlet pipe 4, the second branch pipe 9, and the second-stage ecological treatment unit 3 in sequence, so as to introduce the salt discharge tailwater into the second-stage ecological treatment unit 3.

[0028] This embodiment also includes a second intelligent monitoring and diversion unit. The outlet of the first-stage ecological treatment unit 2 is connected to the second intelligent monitoring and diversion unit. The second intelligent monitoring and diversion unit is connected to the return port of the first-stage ecological treatment unit 2 and the inlet of the second-stage ecological treatment unit 3, respectively. The second intelligent monitoring and diversion unit is electrically connected to the control unit. The second intelligent monitoring and diversion unit is used to monitor a second real-time salinity parameter and transmit it to the control unit. The control unit is used to compare the second real-time salinity parameter with a second preset salinity threshold and control the second intelligent monitoring and diversion unit to connect with the return port of the first-stage ecological treatment unit 2 or the inlet of the second-stage ecological treatment unit 3. Specifically, when the second real-time salinity parameter is greater than the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the return port of the first-stage ecological treatment unit 2; when the second real-time salinity parameter is less than or equal to the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the inlet of the second-stage ecological treatment unit 3. In this embodiment, the second preset salinity threshold is less than the first preset salinity threshold.

[0029] In this embodiment, a second intelligent monitoring and diversion unit based on a second real-time salinity parameter is introduced. When the second real-time salinity parameter is greater than the second preset salinity threshold, the control unit controls the effluent of the first-stage ecological treatment unit 2 to be returned through the return port of the first-stage ecological treatment unit 2. When the second real-time salinity parameter is less than or equal to the second preset salinity threshold, the control unit controls the effluent of the first-stage ecological treatment unit 2 to enter the second-stage ecological treatment unit 3 for secondary deep purification.

[0030] Specifically, the second intelligent monitoring and diversion unit includes a second outlet pipe 10, a third branch pipe 14, a fourth branch pipe 15, a second salinity monitoring component 11, a second delivery pump 12, and a second three-way valve 13. One end of the second outlet pipe 10 is connected to the outlet of the first-stage ecological treatment unit 2, and the other end of the second outlet pipe 10 is sequentially connected to the second salinity monitoring component 11, the second delivery pump 12, and the second three-way valve 13. The first outlet and the second outlet of the second three-way valve 13 are respectively connected to the third branch pipe 14 and the fourth branch pipe 15. The end of the third branch pipe 14 away from the second three-way valve 13 is connected to the return port of the first-stage ecological treatment unit 2, and the end of the fourth branch pipe 15 away from the second three-way valve 13 is connected to the inlet of the second-stage ecological treatment unit 3. The second salinity monitoring component 11, the second delivery pump 12, and the second three-way valve 13 are all electrically connected to the control unit.

[0031] During operation, when the second real-time salinity parameter is greater than the second preset salinity threshold, the control unit controls the second three-way valve 13 to connect the second outlet pipe 10, the third branch pipe 14, and the return port of the first-stage ecological treatment unit 2 in sequence, so that the effluent from the first-stage ecological treatment unit 2 flows back to the first-stage ecological treatment unit 2; when the second real-time salinity parameter is less than or equal to the second preset salinity threshold, the control unit controls the second three-way valve 13 to connect the second outlet pipe 10, the fourth branch pipe 15, and the inlet of the second-stage ecological treatment unit 3 in sequence, so that the effluent from the first-stage ecological treatment unit 2 is introduced into the second-stage ecological treatment unit 3.

[0032] To facilitate control of the effective water depth and hydraulic residence time of the first-stage ecological treatment unit 2, a first inlet valve and a first outlet valve are respectively installed at the inlet and outlet of the first-stage ecological treatment unit 2. A first depth monitoring component 16 is installed in the first-stage ecological treatment unit 2, and the first inlet valve, the first outlet valve, and the first depth monitoring component 16 are all electrically connected to the control unit. In this embodiment, the first depth monitoring component 16 is a first depth sensor.

[0033] To facilitate control of the effective water depth and hydraulic residence time of the second-stage ecological treatment unit 3, a second inlet valve and a second outlet valve are respectively installed at the inlet and outlet of the second-stage ecological treatment unit 3. A second depth monitoring component 17 is installed in the second-stage ecological treatment unit 3. The second inlet valve, the second outlet valve, and the second depth monitoring component 17 are all electrically connected to the control unit. In this embodiment, the second depth monitoring component 17 is a second depth sensor.

[0034] Based on the influent salinity, the first depth monitoring component 16 monitors the effective water depth of the first-stage ecological treatment unit 2 in real time and feeds it back to the control unit. The control unit then adjusts the first inlet valve and the first outlet valve accordingly to control the effective water depth and hydraulic retention time (HRT) of the first-stage ecological treatment unit 2. Similarly, the second depth monitoring component 17 monitors the effective water depth of the second-stage ecological treatment unit 3 in real time and feeds it back to the control unit. The control unit then adjusts the second inlet valve and the second outlet valve accordingly to control the effective water depth and hydraulic retention time (HRT) of the second-stage ecological treatment unit 3.

[0035] Under high salinity conditions, the water level of the first-stage ecological treatment unit 2 is maintained at a shallow level to enhance evapotranspiration and facilitate salt reduction through halophyte enrichment. Specifically, the effective water depth of the first-stage ecological treatment unit 2 is controlled at 0.3m~0.5m, with a hydraulic retention time (HRT) of ≥3 days. Under normal conditions, the hydraulic retention time of the second-stage ecological treatment unit 3 is extended to compensate for the decrease in microbial denitrification rate caused by salt stress. Specifically, the effective water depth of the second-stage ecological treatment unit 3 is controlled at 0.4m~0.8m, with an HRT of ≥5 days.

[0036] In this specific embodiment, the first real-time salinity parameter is the first real-time TDS, and the first salinity monitoring component 5 is the first TDS sensor. The first preset salinity threshold T1 is set to 10 g / L~15 g / L.

[0037] In this specific embodiment, the second real-time salinity parameter is the second real-time TDS, and the second salinity monitoring component 11 is the second TDS sensor. The second preset salinity threshold T2 is set to 8 g / L~10 g / L, and the second preset salinity threshold T2 is less than the first preset salinity threshold T1.

[0038] In this specific embodiment, the first salt-tolerant plant community 18 adopts Salicornia and / or Suaeda salsa.

[0039] In this specific embodiment, the second salt-tolerant plant community includes a highly salt-tolerant zone plant community 19, a transition zone plant community 20, and a deep purification zone plant community 21, arranged sequentially from the inlet near the second-level ecological treatment unit 3 to the outlet near the second-level ecological treatment unit 3. The salt tolerance of the highly salt-tolerant zone plant community 19, the transition zone plant community 20, and the deep purification zone plant community 21 decreases sequentially while their purification capacity increases sequentially. The highly salt-tolerant zone plant community 19 uses reeds, the transition zone plant community 20 uses tamarisk, and the deep purification zone plant community 21 uses calamus and / or canna lilies. The effluent flows sequentially through the plant community configuration section with decreasing salt tolerance and increasing purification capacity, completing the main nitrogen and phosphorus removal purification.

[0040] In this specific embodiment, the impermeable barrier layer is a composite geomembrane or a compacted clay layer, and the permeability coefficient of the impermeable barrier layer is no greater than 1×10⁻⁶.-7 cm / s.

[0041] In this specific embodiment, the storage unit 1 is a storage tank, and the control unit is a controller.

[0042] This embodiment also provides a purification method based on an adaptive ecological purification system for saline tailwater discharge from coastal saline-alkali land, including the following steps: Step 1: The tailwater from the coastal saline-alkali land is fed into the storage unit 1, and the salinity parameters of the water effluent from the storage unit 1 are monitored in real time by the first intelligent monitoring and diversion unit to obtain the first real-time salinity parameters.

[0043] Step 2: Based on the comparison between the first real-time salinity parameter and the first preset salinity threshold, the control unit automatically controls the first intelligent monitoring and diversion unit to perform dynamic switching of the hydraulic path: when the first real-time salinity parameter is greater than the first preset salinity threshold, the effluent is introduced into the first-stage ecological treatment unit 2, where highly salt-tolerant pioneer plants resist high osmotic pressure stress; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the effluent is introduced into the second-stage ecological treatment unit 3 to complete conventional nitrogen and phosphorus removal.

[0044] This embodiment uses a comparative experiment method. All data from the comparative examples and the embodiment are derived from the actual operation monitoring of a saline-alkali land improvement demonstration area.

[0045] Overview of the demonstration area: A newly formed saline-alkali land, with tailwater from underground pipes / open ditches. The TDS fluctuates between 2g / L and 30g / L (extremely high in the dry season and lower in the rainy season), the TN average is 15 mg / L, and the TP average is 1.5mg / L.

[0046] Experimental setup: Comparative Example 1: Conventional salt-tolerant constructed wetland (single configuration, static operation): using a single impermeable layer (permeability coefficient 1×10⁻⁶). -6 (cm / s), all reeds are planted, and the static fixed hydraulic retention time (HRT) is 5 days.

[0047] Example 1: Adaptive ecological purification system (tiered configuration, dynamic scheduling) as described in this example: A seepage-proof isolation layer (permeability coefficient 1×10⁻⁶) is used. -7 The first TDS sensor at the front end is linked with the first three-way valve 7, and the first preset salinity threshold T1 = 15 g / L. The system is configured with a first-level ecological treatment unit 2 (Salix babylonica) and a second-level ecological treatment unit 3 (reed-tamarisk-calamus gradient zone), and the HRT is dynamically adjusted according to salinity.

[0048] Steady-state nitrogen and phosphorus removal was validated under extreme high salinity stress. Specifically, the operating scenario was a coastal dry season (e.g., April-May each year), where rising temperatures and high evaporation rates caused a rapid increase in TDS concentration in the brine effluent. This experiment simulated extreme high salinity conditions (average influent TDS 19.5 g / L). After two weeks of continuous monitoring, the pollutant removal rates after system stabilization are shown in Table 1. Table 1: Comparison of energy efficiency between Comparative Example 1 and Example 1 under extreme high-salinity conditions

[0049] The data in Table 1 clearly demonstrates the significant advancements of this embodiment compared to conventional technologies: Reasons for the collapse of conventional technology (Comparative Example 1): Under the high osmotic pressure stress of TDS of nearly 20 g / L, due to the lack of dynamic diversion protection, the conventional salt-tolerant plant reed in Comparative Example 1 suffered severe physiological drought death, and the activity of biological denitrifying bacteria enzymes was inhibited, resulting in a TN removal rate of only 8.7%, and the system was almost paralyzed.

[0050] The synergistic effect mechanism of this embodiment is confirmed (Example 1): Example 1 activates the intelligent diversion mechanism through online TDS sensing, completely diverting the high-salinity tailwater to the first-level ecological treatment unit 2 (Salix matsudana area). It makes full use of the high cell sap osmotic pressure characteristics of the pioneer plant community, which not only maintains a stable enrichment and salt reduction capacity (TDS removal rate of 13.8%), but also achieves efficient steady-state treatment of 45.3% TN and 55.1% TP under extreme high salt stress, which strongly demonstrates the technical advancement of the dynamic compensation mechanism in this embodiment.

[0051] Verification of treatment efficiency and soil salinization prevention under full dynamic operating conditions. Specifically, the operating background: the demonstration area was put into operation for the first year, experiencing a full cycle of drastic fluctuations including low salinity during the rainy season (TDS ~8g / L), high salinity during the dry season (TDS ~25g / L), and agricultural fertilization (nutrient pulse). This experiment aims to demonstrate the ability of this embodiment to solve the problem of low efficiency in low salinity periods for purely extreme salt-tolerant plants.

[0052] Test group settings: Add comparative example 2: fully extreme salt-tolerant wetland - fully planted with Salicornia glutinosa, static HRT=5 days.

[0053] Example 1: Adaptive ecological purification system (tiered configuration, dynamic scheduling) as described in this example: A seepage-proof isolation layer (permeability coefficient 1×10⁻⁶) is used. -7 The first TDS sensor at the front end is linked with the first three-way valve 7, and the first preset salinity threshold T1 = 15 g / L. The system is equipped with a first-level ecological treatment unit 2 (Salix babylonica) and a second-level ecological treatment unit 3 (reed-tamarisk-calamus gradient), and the HRT is dynamically adjusted according to salinity.

[0054] Table 2 shows the overall TN removal rate comparison data of the system during the rainy season and low salinity period (TDS ~8g / L, less than T1 =15g / L): Table 2: Comparison of nitrogen and phosphorus removal efficiencies between Comparative Example 2 and Example 1 under low-salt conditions

[0055] The data in Table 2 addresses industry biases regarding single-plant configurations: Limitations of pure extreme salt-tolerant wetlands (Comparative Example 2): Although Salicornia is extremely salt-tolerant, its biomass is relatively small and its rhizosphere space is limited. Under low-salt conditions, its nitrogen and phosphorus removal load is not as good as that of conventional wetland plants, resulting in drastic fluctuations in the average purification performance throughout the year.

[0056] This embodiment has an adaptive advantage (Embodiment 1): When TDS is below 15g / L, the first three-way valve 7 directs the tailwater to the second-stage ecological treatment unit 3 (reed-tamarisk-calamus gradient zone), giving full play to the advantages of reeds and other plants in low salinity, large biomass and high decontamination rate, and achieving efficient treatment at all times under dynamic fluctuation conditions.

[0057] A rigorous verification of soil salinization prevention safety was conducted, specifically addressing the bottleneck of secondary salinization caused by high water levels, as highlighted in the background technology. Comparative Example 1 (a regulating reservoir with an impermeability coefficient of 1×10⁻⁶) underwent continuous dynamic monitoring for 12 months. -6 (cm / s) and the regulating tank of Example 1 (seepage prevention coefficient ≤1×10) -7 Soil salinity (cm / s) of farmland at the base and on the outer sidewalls. Monitoring data are shown in Table 3. Table 3: Safety monitoring data of soil salinity around Comparative Example 1 and Example 1 for 12 consecutive months

[0058] The data in Table 3 fundamentally confirms the non-obviousness of the security features of this embodiment: Confirmation of conventional seepage prevention collapse (Comparative Example 1): Comparative Example 1 uses a permeability coefficient of 1×10 -6 During the dry season when the wetland is operating at high water levels, a single anti-seepage layer with a flow rate of cm / s will cause severe backflow and infiltration of high-concentration saline water due to hydraulic pressure difference. This will cause the salinity of the surrounding farmland soil to soar (from 0.32% to 0.88%, p<0.05, a significant increase), which will seriously weaken the overall benefits of the salt drainage and improvement project.

[0059] Physical isolation in this embodiment (Example 1): Example 1 uses a permeability coefficient ≤1×10 -7Even under conditions of high water levels and extremely high salinity during the dry season, the seepage barrier layer with a flow rate of cm / s prevented any abnormal increase in soil salinity in the surrounding farmland (statistical analysis showed p>0.05, indicating no significant difference). The data in the table strongly confirms this specific numerical range (≤1×10⁻⁶). -7 (cm / s) can effectively reduce the risk of secondary salt return.

[0060] As can be seen, compared with the prior art, this embodiment has achieved the following outstanding substantive features and significant technical progress: Firstly, it can adapt to high-salt stress environments, improving purification stability under high-salt conditions. Technical features and mechanisms: This embodiment introduces an intelligent diversion mechanism based on real-time TDS sensing. When the influent exhibits high-salt characteristics (TDS>T1), the system automatically switches to the first-level ecological treatment unit 2. This area utilizes the high osmotic pressure characteristics of pioneer plants (such as Salicornia glutinosa) to resist physiological dehydration caused by external high osmotic pressure.

[0061] Quantitative effect: Data from the example show that under the condition of influent TDS of 19.5 g / L, the TN removal rate of conventional constructed wetlands is 8.7%; while the system in this example, through diversion and treatment by the first-stage ecological treatment unit 2, maintains the TN removal rate at 45.3%, effectively improving the problem of conventional wetlands being prone to failure under high salinity.

[0062] Secondly, to overcome the limitations of a single plant configuration and to consider treatment efficiency under different salinity levels, the technical features and mechanism are as follows: Addressing the issue of low treatment load during low-salinity periods when planting only extremely salt-tolerant plants, this embodiment incorporates a second-level ecological treatment unit 3 (including a plant configuration of reeds, tamarisk, and calamus). During low-salinity periods (TDS≤T1), the system automatically directs the effluent into the second-level ecological treatment unit 3, utilizing the larger biomass and rhizosphere space of conventional wetland plants for nitrogen and phosphorus removal.

[0063] Quantitative results: Data from the example show that under low salinity conditions during the rainy season, the 3TN removal rate of the second-stage ecological treatment unit in this example is 72.8%, which is a significant improvement compared to the 27.4% of the single pioneer plant control group, and adapts to the seasonal fluctuations in salinity of the salt discharge tailwater.

[0064] Thirdly, severing the hydraulic connection effectively prevents secondary salinization of the surrounding soil. Technical features and mechanism: Addressing the issue of tailwater backflow caused by wetland operating water levels exceeding the surrounding groundwater layer, this embodiment incorporates permeability coefficients ≤1×10⁻⁶ on the foundation and sidewalls of storage unit 1 and each treatment unit. -7 A seepage-proof isolation layer with a flow rate of cm / s cuts off the hydraulic connection between the high-concentration tailwater and the groundwater in the surrounding farmland.

[0065] Quantitative effect: Monitoring data over 12 consecutive months showed that, in conventional seepage prevention (1×10⁻⁶),-6 Under the condition that the soil salinity around the system (cm / s) rises to 0.88%, the soil salinity around the system in this embodiment remains stable at around 0.33% (p>0.05, no significant difference), thus controlling the risk of secondary salinization.

[0066] Fourthly, dynamically adjusting hydraulic parameters to compensate for the impact of salt stress on microbial activity. Technical features and mechanisms: In this embodiment, the hydraulic residence time (HRT) and effective water depth are adaptively adjusted by linking the TDS sensor, depth monitoring component, inlet valve, and outlet valve.

[0067] Results: In high-salt mode, shallow water level (0.3~0.5m) was maintained to facilitate salt accumulation and reduction by pioneer plants; in conventional mode, the HRT (≥5 days) was extended to compensate for the decrease in nitrification / denitrification rate caused by salt stress by increasing hydraulic retention time, thus optimizing the treatment conditions under different operating conditions.

[0068] Fifthly, the system's control structure is streamlined, facilitating engineering applications. The core diversion decision-making process requires only the linkage between a TDS sensor and a three-way valve, eliminating the need for complex high-performance computing equipment or large-scale meteorological and hydrological forecasting models. This streamlined hardware architecture reduces construction and subsequent maintenance costs, making it suitable for large-scale deployment in coastal saline-alkali areas with relatively harsh environmental conditions and weak communication infrastructure.

[0069] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A self-adaptive ecological purification system for wastewater discharge from coastal saline-alkali land, characterized in that, The system includes a storage unit, a first intelligent monitoring and diversion unit, a first-stage ecological treatment unit, a second-stage ecological treatment unit, and a control unit. The storage unit receives and stores the wastewater from the coastal saline-alkali land. The outlet of the storage unit is connected to the first intelligent monitoring and diversion unit, which is connected to the inlet of both the first-stage and second-stage ecological treatment units. All three units have impermeable isolation layers on their inner walls. The first-stage ecological treatment unit contains a first salt-tolerant plant community, and the second-stage ecological treatment unit contains a second salt-tolerant plant community. The salinity tolerance threshold of the first salt-tolerant plant community is greater than that of the second salt-tolerant plant community. Threshold; the first intelligent monitoring diversion unit is electrically connected to the control unit. The first intelligent monitoring diversion unit is used to monitor a first real-time salinity parameter and transmit it to the control unit. The control unit is used to compare the first real-time salinity parameter with a first preset salinity threshold and control the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit or the inlet of the second-level ecological treatment unit. Specifically, when the first real-time salinity parameter is greater than the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the first-level ecological treatment unit; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the control unit controls the first intelligent monitoring diversion unit to connect with the inlet of the second-level ecological treatment unit.

2. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The first intelligent monitoring and diversion unit includes a first outlet pipe, a first branch pipe, a second branch pipe, a first salinity monitoring component, a first delivery pump, and a first three-way valve. One end of the first outlet pipe is connected to the outlet of the storage unit, and the other end of the first outlet pipe is sequentially connected to the first salinity monitoring component, the first delivery pump, and the first three-way valve. The first outlet and the second outlet of the first three-way valve are respectively connected to the first branch pipe and the second branch pipe. The end of the first branch pipe away from the first three-way valve is connected to the inlet of the first-stage ecological treatment unit, and the end of the second branch pipe away from the first three-way valve is connected to the inlet of the second-stage ecological treatment unit. The first salinity monitoring component, the first delivery pump, and the first three-way valve are all electrically connected to the control unit.

3. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The system also includes a second intelligent monitoring and diversion unit. The outlet of the first-stage ecological treatment unit is connected to the second intelligent monitoring and diversion unit. The second intelligent monitoring and diversion unit is connected to both the return port of the first-stage ecological treatment unit and the inlet of the second-stage ecological treatment unit. The second intelligent monitoring and diversion unit is electrically connected to the control unit. The second intelligent monitoring and diversion unit is used to monitor a second real-time salinity parameter and transmit it to the control unit. The control unit is used to compare the second real-time salinity parameter with a second preset salinity threshold and control the second intelligent monitoring and diversion unit to connect with either the return port of the first-stage ecological treatment unit or the inlet of the second-stage ecological treatment unit. Specifically, when the second real-time salinity parameter is greater than the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the return port of the first-stage ecological treatment unit; when the second real-time salinity parameter is less than or equal to the second preset salinity threshold, the control unit controls the second intelligent monitoring and diversion unit to connect with the inlet of the second-stage ecological treatment unit.

4. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 3, characterized in that, The second intelligent monitoring and diversion unit includes a second outlet pipe, a third branch pipe, a fourth branch pipe, a second salinity monitoring component, a second delivery pump, and a second three-way valve. One end of the second outlet pipe is connected to the outlet of the first-stage ecological treatment unit, and the other end of the second outlet pipe is sequentially connected to the second salinity monitoring component, the second delivery pump, and the second three-way valve. The first outlet and the second outlet of the second three-way valve are respectively connected to the third branch pipe and the fourth branch pipe. The end of the third branch pipe away from the second three-way valve is connected to the return port of the first-stage ecological treatment unit, and the end of the fourth branch pipe away from the second three-way valve is connected to the inlet of the second-stage ecological treatment unit. The second salinity monitoring component, the second delivery pump, and the second three-way valve are all electrically connected to the control unit.

5. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The first-stage ecological treatment unit is equipped with a first inlet valve and a first outlet valve at its inlet and outlet, respectively. The first-stage ecological treatment unit is also equipped with a first depth monitoring component. The first inlet valve, the first outlet valve, and the first depth monitoring component are all electrically connected to the control unit.

6. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The second-stage ecological treatment unit is equipped with a second inlet valve and a second outlet valve at its inlet and outlet, respectively. The second-stage ecological treatment unit is also equipped with a second depth monitoring component. The second inlet valve, the second outlet valve, and the second depth monitoring component are all electrically connected to the control unit.

7. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The first salt-tolerant plant community consists of Salicornia and / or Suaeda salsa.

8. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The second salt-tolerant plant community includes a highly salt-tolerant zone plant community, a transition zone plant community, and a deep purification zone plant community arranged sequentially from the inlet near the second-level ecological treatment unit to the outlet near the second-level ecological treatment unit. The highly salt-tolerant zone plant community uses reeds, the transition zone plant community uses tamarisk, and the deep purification zone plant community uses calamus and / or canna lily.

9. The adaptive ecological purification system for wastewater discharge from coastal saline-alkali land according to claim 1, characterized in that, The impermeable barrier layer is a composite geomembrane or a compacted clay layer, and the permeability coefficient of the impermeable barrier layer is not greater than 1×10⁻⁶. -7 cm / s.

10. A purification method based on an adaptive ecological purification system for wastewater discharge from coastal saline-alkali land as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: The tailwater from the coastal saline-alkali land is collected into the storage unit, and the salinity parameters of the water effluent from the storage unit are monitored in real time through the first intelligent monitoring and diversion unit to obtain the first real-time salinity parameter. Step 2: Based on the comparison result of the first real-time salinity parameter and the first preset salinity threshold, the control unit automatically controls the first intelligent monitoring diversion unit to perform dynamic switching of the hydraulic path: when the first real-time salinity parameter is greater than the first preset salinity threshold, the effluent is introduced into the first-level ecological treatment unit; when the first real-time salinity parameter is less than or equal to the first preset salinity threshold, the effluent is introduced into the second-level ecological treatment unit.

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