Coastal saline-alkali land concealed conduit-water-collecting well pool salt elimination system

Abstract

The invention relates to a coastal saline-alkali soil concealed conduit-water collecting well pool salt elimination system. The system comprises a monitoring regulation and control system, and a water collecting system and a purification treatment system which are connected in sequence; the water collecting system comprises a concealed pipe water collecting system and a water collecting well pool system; the monitoring regulation and control system is used for detecting operation states of other systems and carrying out regulation and control; the concealed pipe water collecting system is used for collecting saline water in soil and conveying the saline water into the water collecting well pool system; the water collecting well pool system is used for precipitating, filtering and buffering the saline water conveyed by the concealed pipe water collecting system; the purification treatment system is used for carrying out secondary filtration and safe discharge on effluent of the water collecting well pool system; the water collecting well pool system comprises a sedimentation cavity, a filtering cavity and a buffering cavity. The technical problems that in the prior art, a salt discharging system is prone to secondary pollution, poor in adaptability to coastal areas, poor in water discharging efficiency in the complex environment of coastal saline-alkali soil, prone to pipeline blockage and needing to be frequently maintained can be solved.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land improvement technology, and in particular to a coastal saline-alkali land underground pipe-collection well salt drainage system. Background Technology

[0002] Coastal saline-alkali land is an important reserve land resource in my country, but its improvement and utilization have always faced severe challenges. Unlike inland saline-alkali land, the formation and evolution of coastal saline-alkali land are heavily influenced by the marine environment, mainly manifested in the following ways: ① The groundwater level in coastal areas is shallow and susceptible to the periodic backwater effect of tides, resulting in high and unstable groundwater or ditch water levels. Traditional underground drainage systems experience a sharp decline in efficiency under tidal backwater, and may even experience backflow; ② The soil and groundwater are mainly composed of sodium chloride, with high salt content, which is highly corrosive to concrete and metal components, greatly shortening the service life of engineering facilities; ③ Frequent tidal activities can easily cause seawater to backflow through drainage ditches, rendering remediation efforts futile; ④ The soil texture is complex, with some areas having high silt content and clay layers. The simple "fixed filter media + guide pipe" structure in existing technologies is easily blocked by fine silt particles, and there is a lack of effective dredging methods, making the drainage system prone to failure.

[0003] While existing technologies have attempted to improve precipitation or drainage efficiency by using structures such as guide pipes and booster pumps to rapidly direct water to aquifers, they still have significant limitations. For example, existing desalination systems often have a relatively singular function, focusing solely on the large-scale discharge of high-salinity wastewater. Excessive discharge of high-salinity wastewater can easily lead to secondary pollution of local water bodies due to salinity accumulation. Furthermore, existing desalination systems generally only discharge wastewater without addressing the underlying causes, lacking synergy with soil improvement and ecological restoration. This often necessitates the construction of separate ecological restoration systems, increasing costs and complexity. In addition, to ensure drainage effectiveness, existing technologies often incorporate various complex and expensive mechanical devices into the desalination system, such as negative pressure pumps or multi-stage pumping stations within the drainage pipes. However, in the high-salinity, high-siltation environment of coastal areas, these complex devices are prone to frequent malfunctions. This not only reduces the reliability of the desalination system and increases energy consumption but also places significant pressure on its construction, operation, and maintenance, further straining the already limited budget for saline-alkali land management.

[0004] Therefore, there is an urgent need in this field for a coastal saline-alkali land desalination system that can effectively cope with the effects of tides, resist salt corrosion, achieve efficient separation of sediment and resource recovery of salt, and has ecological synergy functions. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a coastal saline-alkali land underground pipe-collection well salt drainage system, which solves the technical problems of the existing salt drainage system being poorly adaptable to coastal areas, having poor drainage efficiency in the complex environment of coastal saline-alkali land and being prone to secondary pollution, and being prone to blockage and requiring frequent maintenance.

[0007] (II) Technical Solution

[0008] This invention provides a submerged pipe-collecting well system for desalination in coastal saline-alkali land, characterized in that it includes: a monitoring and control system and a water collection system and a purification system connected in sequence; the water collection system includes a submerged pipe water collection system and a collecting well system.

[0009] The monitoring and control system is used to detect and control the operating status of other systems; the underground pipe water collection system is used to collect saline water in the soil and transport it to the water collection well system; the water collection well system is used to precipitate, filter and buffer the saline water transported from the underground pipe water collection system; the purification treatment system is used to perform secondary filtration and safe discharge of the effluent from the water collection well system.

[0010] The underground pipe water collection system includes several pipe network subsystems, and the water collection well system is located at the end of one or more pipe network subsystems. The water collection well system includes a sedimentation chamber for sedimentation of silt in the effluent of the underground pipe water collection system, a filtration chamber for preliminary filtration of the effluent from the sedimentation chamber, and a buffer chamber for buffering the effluent from the filtration chamber and providing redundant space for tidal water level changes.

[0011] Optionally, the purification system includes a purification and diversion system for secondary filtration of the brine transported by the water collection system to reduce its salt content and for diverting the brine according to the salt concentration of the brine obtained after secondary filtration, and an ecological discharge system for receiving the brine generated by the purification and diversion system and discharging and / or reusing it in an ecological manner.

[0012] The ecological discharge system includes an ecological discharge pond for receiving brine with a salt concentration below a predetermined threshold and a recovery and emergency pond for receiving brine with a salt concentration above a predetermined threshold. The ecological discharge pond is provided with an ecological salt filter layer and a drainage pipe arranged in sequence along the water flow direction. The drainage pipe is connected to the groundwater layer or drainage ditch.

[0013] The buffer chamber is equipped with a water level monitoring instrument; the purification and diversion system includes a submersible pump, which is used to quickly discharge the brine in the purification and diversion system into the recycling and emergency pool of the ecological discharge system when the water level in the buffer chamber is too high.

[0014] Optionally, each pipeline subsystem includes several underground water collection pipes, multiple primary delivery pipes, and secondary delivery pipes; several seepage outlets are provided on the pipe walls of the underground water collection pipes; the underground water collection pipes, primary delivery pipes, and secondary delivery pipes are all inclined, with a slope of 0.2%-0.6%; several underground water collection pipes are connected to one primary delivery pipe; multiple primary delivery pipes are connected to the secondary delivery pipes;

[0015] The secondary delivery pipe is also provided with several low-pressure node cavities to enhance the low-pressure environment in the primary delivery pipe; along the brine flow direction in the secondary delivery pipe, the low-pressure node cavities include a constriction cone, a throttling tube, and a diffusion cone; the primary delivery pipe is connected to the side wall of the constriction cone or the throttling tube.

[0016] Optionally, the two ends of the water collection pipe are a venting end and a water outlet end, respectively; the water outlet end is connected to the primary delivery pipe; the venting end is equipped with a vent pipe, which is higher than the ground surface and its outlet is connected to the outside; the diameter of the outlet of the vent pipe does not exceed 20% of the diameter of the water collection pipe.

[0017] A flow meter is installed at the outlet of the primary delivery pipe to monitor the flow rate of the brine output from the primary delivery pipe; a flow regulating valve is installed at the outlet of the secondary delivery pipe; both the flow meter and the flow regulating valve are connected to the monitoring and control system; the outlet of the secondary delivery pipe is connected to the collection well system.

[0018] Optionally, the concealed pipe water collection system also includes a flushing subsystem; the flushing subsystem is connected to the relatively high end of the secondary delivery pipe and is used to inject clean water into the secondary delivery pipe.

[0019] Optionally, the purification and diversion system includes a secondary filtration chamber and a diversion valve; the inlet of the secondary filtration chamber is connected to the collection well system; inside the secondary filtration chamber, a zeolite adsorption layer, a submersible pump, and a water quality monitoring unit are sequentially arranged along the brine flow direction; the water quality monitoring unit is used to monitor the salt concentration of the brine after passing through the zeolite adsorption layer; the outlet of the secondary filtration chamber is connected to the diversion valve; the diversion valve diverts the brine according to the monitoring results of the water quality monitoring unit; both the water quality monitoring unit and the diversion valve are communicatively connected to the monitoring and control system.

[0020] Optionally, the ecological discharge pond includes a pond body; the pond body is an above-ground or semi-underground structure with a top cover; the ecological salt filter layer and drainage pipe are located at the bottom of the pond body.

[0021] Optionally, according to the water flow direction, the ecological salt-filtering layer includes a gravel filter layer, a coarse sand filter layer, a bacterial-carrying ceramic particle filter layer, and a fine sand filter layer arranged in sequence; the drainage pipe includes a filtration section and a conveying section; the filtration section is set in the pool body, and the conveying section passes through the pool body and is connected to the drainage ditch or groundwater layer; the filtration section of the drainage pipe is provided with filter holes with an opening rate of 15-20%; the pore size of the filter holes is smaller than the particle size of the fine sand in the fine sand filter layer.

[0022] The particle size of the ceramsite in the bacterial-loaded ceramsite layer is 5-10 mm, and the porosity is not less than 30%. The bacterial-loaded ceramsite layer is loaded with salt-tolerant bacteria for removing organic pollutants from brine.

[0023] Optionally, the top cover is provided with several planting holes, in which deep-rooted salt-tolerant plants are planted. The deep-rooted salt-tolerant plants are at least one of the following: Suaeda salsa, mangrove, Suaeda salsa, reed, Salicornia glutinosa, Deer antler velvet, Salix babylonica, and Elaeagnus angustifolia. The bottom of the top cover is also connected to a hanging cage, which is filled with a soil conditioner. The soil conditioner includes at least one of the following: crushed brick, fly ash, desulfurized gypsum, phosphogypsum, and lime.

[0024] Optionally, the recovery and emergency pool includes an emergency buffer pool for temporarily storing brine with a salt concentration higher than a predetermined threshold, and an evaporation crystallization pool connected in sequence; the top of the evaporation crystallization pool is covered with an insulating membrane to increase the temperature inside the evaporation crystallization pool; the emergency buffer pool also receives brine discharged from the buffer chamber.

[0025] (III) Beneficial Effects

[0026] The coastal saline-alkali land underground pipe-collection well salt discharge system (hereinafter referred to as the salt discharge system) of this invention, compared with the prior art, achieves integrated "sedimentation-filtration-buffering" treatment of water from the underground pipe through the series design of sedimentation chamber, filtration chamber and buffer chamber in its water collection system. This achieves effective sedimentation of high-sand-content brine, avoiding excessive siltation and blockage of subsequent systems. At the same time, the buffer chamber provides valuable redundancy for the system to cope with tidal fluctuations, greatly enhancing the system's environmental adaptability and operational stability. Furthermore, the filtration chamber and purification system, through two filtration processes, effectively reduce the salt concentration in the brine discharged by the salt discharge system, which is beneficial to the environment.

[0027] Meanwhile, the buffer chamber can also be combined with the monitoring and control system for water level monitoring, enabling the desalination system to maintain normal hydraulic circulation even in tidal environments, greatly enhancing the system's environmental adaptability and operational stability.

[0028] Furthermore, compared to existing technologies, this invention, through the coordination of a purification and diversion system with an ecological discharge pond system, allocates different treatment paths to the brine collected by this invention based on the different salt concentrations. This not only enables the safe discharge of compliant brine, avoiding the discharge of large amounts of high-concentration brine into the ground and preventing secondary pollution and salt backflow, but also enables the resource recovery of high-concentration brine. While reducing environmental pressure, the recovered salt crystals can also be used as snow melting agents or industrial raw materials, recovering some funds and reducing the budget pressure of the salt discharge system of this invention during operation and maintenance.

[0029] Meanwhile, because the ecological discharge pond of this invention is also equipped with a drainage pipe that directly leads to a drainage ditch or groundwater layer, it can directly guide the brine flowing into the ecological discharge pond into the surface water or groundwater layer. This gives the salt removal system of this invention a faster drainage speed, effectively avoiding the problem of precipitation difficulties caused by clay layers. After passing through the ecological salt filter layer, the salt content of the brine in the ecological discharge pond is further reduced, which can further reduce potential secondary pollution and other problems. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the salt drainage system of the coastal saline-alkali land underground pipe-collection well pool of the present invention;

[0031] Figure 2 This is a schematic diagram of the low-pressure node cavity in the secondary water conveyance underground pipe of the coastal saline-alkali land underground pipe-collection well salt drainage system of the present invention.

[0032] Figure 3 This is a schematic diagram of the ventilation pipe and the water collection pipe of the coastal saline-alkali land underground pipe-water collection well salt drainage system of the present invention.

[0033] Figure 4 This is a schematic diagram of the water collection well system of the coastal saline-alkali land underground pipe-water collection well system of the present invention.

[0034] Figure 5 This is a schematic diagram of the secondary filtration chamber of the coastal saline-alkali land underground pipe-collecting well salt discharge system of the present invention.

[0035] Figure 6 This is a schematic diagram of the semi-underground structure of the ecological discharge pool of the coastal saline-alkali land underground pipe-collection well salt discharge system of the present invention.

[0036] Figure 7 This is a schematic diagram of the above-ground structure of the ecological discharge pool of the coastal saline-alkali land underground pipe-collection well salt discharge system of the present invention;

[0037] Figure 8 This is a schematic diagram of the evaporation crystallization pool of the coastal saline-alkali land underground pipe-collecting well salt discharge system of the present invention.

[0038] [Attached image captions]

[0039] 1: Water collection pipe; 2: Primary delivery pipe; 3: Secondary delivery pipe; 4: Contraction cone pipe; 5: Throttling pipe; 6: Diffusion cone pipe; 7: Vent pipe; 8: Siphon pipe; 9: Sedimentation chamber; 10: Filtration chamber; 11: Buffer chamber; 12: First partition wall; 13: First water outlet; 14: Second partition wall; 15: Second water outlet; 16: Sludge hopper; 17: Sludge scraper; 18: Dredging pipe; 19: Guide plate; 20: Support layer; 21: Main filter layer; 22: Adsorption layer; 23: Backwash pipe; 24: Mesh screen ; 25: Water level monitoring instrument; 26: Secondary filtration chamber; 27: Diverter valve; 28: Zeolite adsorption layer; 29: Submersible pump; 30: Water quality monitoring unit; 31: Pool body; 32: Ecological salt filter layer; 33: Groundwater layer; 34: Drainage pipe; 35: Fine sand filter layer; 36: Bacterial-loaded ceramic granule filter layer; 37: Coarse sand filter layer; 38: Gravel filter layer; 39: Top cover; 40: Planting hole; 41: Hanging cage; 42: Soil conditioner; 43: Evaporation crystallization pool; 44: Insulation membrane; 45: Water collection tank. Detailed Implementation

[0040] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, this invention provides a submerged pipe-collecting well system for desalination in coastal saline-alkali land, comprising: a monitoring and control system, and a water collection system and a purification system connected in sequence. The water collection system includes a submerged pipe water collection system and a collecting well system.

[0042] The monitoring and control system is used to detect and regulate the operating status of other systems. The underground pipe water collection system is used to collect saline water from the soil and transport it to the collection well system. The collection well system is used to settle, filter, and buffer the saline water transported by the underground pipe water collection system. The purification system is used to perform secondary filtration and safe discharge of the effluent from the collection well system.

[0043] When constructing the salt drainage system of this invention, site survey and design should be carried out first: conduct geological surveys of the target coastal saline-alkali area to determine the distribution and thickness of the clay layer with water-resistant properties (i.e., the clay layer that is not easily permeable by water), the condition of natural water channels, and the groundwater depth in the area; based on the survey results, plan the laying route of the underground pipes in the underground pipe water collection system, the location and number of the water collection well system and the ecological discharge pond, etc. (If there is a clay layer in the area and it is necessary to discharge the collected salt water into the groundwater, it is necessary to ensure that the drainage pipe 34 of the ecological discharge pond can penetrate the clay layer and extend to the groundwater layer 33 below the clay layer. Such preliminary planning should be adapted to local conditions and will not be elaborated here).

[0044] like Figure 1As shown, preferably, the underground water collection system includes several pipe network subsystems. Each pipe network subsystem includes several underground water collection pipes 1, multiple primary delivery pipes 2, and secondary delivery pipes 3. Several underground water collection pipes 1 are connected to one primary delivery pipe 2, and multiple primary delivery pipes 2 are connected to the secondary delivery pipes 3, forming an underground water collection and delivery network. The overall shape of this network can be a conventional herringbone structure or a tree structure, or other shapes, depending on the actual situation, as long as it can effectively collect and deliver water. When laying the underground pipes, they should be laid below the topsoil layer (cultivated layer) and above the clay layer as much as possible along the planned laying route.

[0045] The wall of the water collection pipe 1 is equipped with several seepage ports. Salt water in the soil (formed by water from artificial irrigation or natural rainfall dissolving salt in the soil) can seep into the water collection pipe 1 through the seepage ports, and then be transported to the primary transport pipe 2 through the water collection pipe 1, and then to the secondary transport pipe 3.

[0046] Both the primary delivery pipe 2 and the secondary delivery pipe 3 are seamless pipes with one end closed, and are all laid underground to ensure the full-process sealing of brine during transportation, prevent brine leakage, and ensure the operation of the subsequent flushing subsystem and other related structures, such as preventing salt backflow in the pipeline during the operation of the flushing subsystem.

[0047] The underground water collection pipe 1, the primary delivery pipe 2, and the secondary delivery pipe 3 are all installed at an incline, with their burial depths increasing sequentially. This allows the underground water collection system to transport brine by gravity, avoiding the use of mechanical structures such as negative pressure pumps and ensuring the reliability of the underground water collection system during long-term use. The slope of the underground water collection pipe 1, the primary delivery pipe 2, and the secondary delivery pipe 3 is all 0.2%-0.6%, preferably 0.4%-0.6%, ensuring that the brine can flow entirely by gravity.

[0048] like Figure 2 As shown, the secondary delivery pipe 3 is also provided with several low-pressure node cavities to enhance the low-pressure environment within the primary delivery pipe 2. Along the brine flow direction in the secondary delivery pipe 3, the low-pressure node cavities include a constricting cone 4 (gradually narrowing structure), a throttling pipe 5, and a diffusing cone 6 (gradually expanding structure) connected in sequence. The constricting cone 4 is a gradually narrowing structure, with its diameter gradually decreasing along the brine flow direction until it connects with the throttling pipe 5. The diffusing cone 6 is a gradually expanding structure, with its initial diameter being the same as the throttling pipe 5, and then its diameter gradually increasing along the brine flow direction until it is the same as that of the secondary delivery pipe 3.

[0049] The low-pressure node cavity utilizes the tapered structure of the contraction cone 4, the throttling tube 5, and the expanding structure of the diffusion cone 6 to form a Venturi-like structure. The flow velocity of the brine increases as it passes through the contraction cone 4, reaching its maximum in the throttling tube 5. This creates a low-pressure zone within the low-pressure node cavity, drawing water (and air) from the primary delivery pipe 2 into this low-pressure zone (pressure difference-driven suction). This water mixes with the high-speed water flow in the secondary delivery pipe 3 before flowing away. Simultaneously, because the primary delivery pipe 2 is a seamless pipe, the suction of the brine and air inside also creates a low-pressure environment, further drawing water from the collection pipe 1. This creates a low-pressure environment within the collection pipe 1, allowing it to actively draw brine from the soil, accelerating brine collection, increasing the collection speed and efficiency of the collection pipe 1, and expanding its collection range. This enables the collection of brine over a larger area, further improving the desalination efficiency of the system and preventing brine infiltration and residue. The primary delivery pipe 2 is connected to the side wall of the secondary delivery pipe 3 at the throttling pipe 5 or the contraction cone pipe 4 to ensure the formation of a low-pressure environment in the primary delivery pipe 2. More preferably, the primary delivery pipe 2 is connected to the side wall of the secondary delivery pipe 3 at the throttling pipe 5, and the connection is made with a rounded transition to ensure that the brine flow in the primary delivery pipe 2 smoothly flows into the mainstream in the secondary delivery pipe 3, avoiding excessive turbulence, interfering with the operation of the low-pressure node cavity, and reducing energy loss.

[0050] Preferably, the length of the contraction cone 4 is 1-1.5 times the diameter of the secondary delivery pipe 3, and the length of the throttling pipe 5 is 0.5-1 times the diameter of the secondary delivery pipe 3, while its diameter is 0.35-0.5 times the diameter of the secondary delivery pipe 3. This ensures the stability of the brine flow rate and pressure within the throttling pipe 5 and avoids problems such as blockage, thus ensuring the reliability of the salt drainage system of this invention. The length of the expansion cone is 3-5 times the diameter of the secondary delivery pipe 3. This prevents the brine from separating from the pipe wall and generating eddies, ensuring a smooth water flow, avoiding excessive loss of kinetic energy in the brine, and preventing a decrease in drainage efficiency.

[0051] The materials for the water collection pipe 1, the primary delivery pipe 2, and the secondary delivery pipe 3 should be high-strength materials, such as high-strength PVC + carbon fiber composite pipes, to ensure that they will not deform and can maintain their strength for a long time under conditions of relatively high soil density and high soil pressure in clay areas.

[0052] like Figure 3As shown, the two ends of the water collection pipe 1 are a venting end and a water outlet end, respectively. The water outlet end is connected to the primary conveying pipe 2. The venting end is equipped with a venting pipe 7, the outlet of which is higher than the ground surface and connected to the outside. By venting pipe 7, the internal air pressure of the water collection pipe 1, the primary conveying pipe 2, and the secondary conveying pipe 3 during drainage is balanced, reducing air resistance and improving the initial water collection efficiency. This allows the salt water in the soil to flow smoothly into the water collection pipe 1 and flow smoothly into the primary conveying pipe 2 under the action of gravity at the beginning of artificial watering or natural rainfall, before the salt drainage system of this invention has fully started operating. This ensures that the salt drainage system of this invention can effectively collect salt water even in clay areas where the soil is relatively dense and the water resistance is high.

[0053] Preferably, the diameter of the outlet of the vent pipe 7 does not exceed 20% of the diameter of the water collection pipe 1, and more preferably does not exceed 10%. The smaller diameter of the vent pipe 7 effectively prevents foreign objects from entering. Furthermore, it is important that, due to the small orifice of the vent pipe 7, its ventilation capacity is limited. This effectively maintains the stability of the low-pressure environment within the water collection pipe 1 and the primary delivery pipe 2. Its lower ventilation capacity ensures high suction within the water collection pipe 1 and the primary delivery pipe 2 during the operation of the salt drainage system of this invention, further improving the water collection effect of the salt drainage system. Simultaneously, it allows a certain amount of air to be drawn in during the operation of the salt drainage system, preventing excessive suction within the pipes (excessive pressure difference between the inside and outside of the pipe), which could damage the pipes or surrounding soil, and avoiding backflow problems after the salt drainage system stops.

[0054] Preferably, the outlet of the vent pipe 7 is also equipped with a dust cover.

[0055] Along the direction from the vent end to the outlet end, the density of seepage holes on the pipe wall of the water collection pipe 1 gradually increases. Since the water collection pipe 1 is installed at an angle underground, in clay areas, the deeper it is, the greater the water resistance generally is. By gradually increasing the density of seepage holes, the water collection capacity of the water collection pipe 1 is ensured. The arrangement of the seepage holes can be uniform, spiral, or other distribution methods depending on the actual situation, as long as the permeability is ensured.

[0056] like Figure 2As shown, preferably, the secondary conveying pipe 3 also includes a siphon pipe 8, which is located at the connection between the secondary conveying pipe 3 and the collection well system. The height difference between the two ends of the siphon pipe 8 is not less than 0.5m. The siphon pipe 8 creates a significant height difference within the secondary conveying pipe 3, thereby generating negative pressure at the siphon pipe 8. This siphon draws water from the secondary conveying pipe 3, ensuring a high flow velocity even at a relatively low overall slope. This improves the effectiveness of the low-pressure node cavity and enhances the water conveyance efficiency of the pipe network subsystem, thereby increasing the drainage and desalination efficiency of the desalination system of this invention. It also ensures that the water in the collection well system has sufficient driving force to enter the next system. Furthermore, the high flow velocity further prevents the deposition of impurities in the secondary conveying pipe 3, avoiding blockages and improving the reliability of the desalination system of this invention.

[0057] Preferably, the slope of the siphon pipe 8 is not less than 1%, and more preferably 1%-5%. This further ensures the water flow rate.

[0058] The outer side of the water collection pipe 1 is covered with a water collection filter layer to prevent excessive impurities from entering the pipe. This filter layer can be made of quartz sand, straw, geotextile, or other filter materials to intercept impurities and prevent them from entering the pipe. A removable stainless steel filter screen or similar structure can also be added inside the pipe for filtration. These conventional anti-clogging methods can be used in the salt drainage system of this invention and will not be elaborated upon here. Furthermore, the pipe diameters, lengths, and orifice diameters of the seepage points on the water collection pipe 1, primary delivery pipe 2, and secondary delivery pipe 3 can be designed and selected according to the actual salinity of the saline-alkali land, rainfall intensity, and amount of artificial irrigation, using conventional methods. These details will not be elaborated upon here.

[0059] The underground pipe water collection system of the present invention relies entirely on gravity for water flow. Through the coordinated operation of the vent, low-pressure node cavity and siphon 8, the system can maintain efficient and stable water collection and transportation capacity even in coastal clay areas with dense soil and high water resistance. Moreover, it has extremely low energy consumption and high reliability.

[0060] Furthermore, this invention can achieve high water collection, salt removal, and drainage effects without the need for an external pump, and its pipelines are not prone to blockage. It not only has high reliability, but also low construction costs and low investment in operation and maintenance.

[0061] Preferably, a flow meter is installed at the outlet of the primary delivery pipe 2 to monitor the flow rate of the brine output from the primary delivery pipe 2. A flow regulating valve is installed at the outlet of the secondary delivery pipe 3 (or the outlet of the siphon pipe 8) to control the maximum allowable flow rate of brine in the secondary delivery pipe 3. Both the flow meter and the flow regulating valve are communicatively connected to the monitoring and control system.

[0062] The flow regulating valve controls the maximum flow rate of water allowed through the secondary delivery pipe 3 based on the flow rate of the brine in all the primary delivery pipes 2 monitored by the flow meter, maintaining the brine flow in the secondary delivery pipe 3 at full capacity, ensuring the water flow rate and the stability of the low-pressure environment formed at the low-pressure node cavity.

[0063] In the secondary conveying pipe 3, a set of pressure sensors and one-way valves are installed every 30-80 meters along the water flow direction. When the tide causes the external water level to rise, and the water pressure inside the pipe exceeds the warning threshold (generally 0.3 MPa), the valves automatically open to release pressure to the outside, preventing excessive pressure inside the pipe from affecting drainage efficiency or even damaging the pipe. When the tide recedes and the water pressure inside the pipe falls below the safety threshold (generally 0.1 MPa), the valves automatically close to maintain the necessary operating head inside the concealed pipe system and ensure drainage power. By using pressure sensors and one-way valves, pressure fluctuations caused by tides can be effectively mitigated, ensuring the stable operation of the salt discharge system of this invention under different tidal conditions.

[0064] The theoretical drainage capacity of a single concealed pipe system is calculated using the following formula: Q = K•i•k•A. Where Q is the theoretical drainage capacity of a single concealed pipe (m³). 3 / s). K is the soil permeability coefficient (m / s) (the K value of sandy soil in coastal saline-alkali areas is generally 1×10⁻⁶ m / s). -4 -5×10 - 4 m / s, the K value for clay soils is generally 1×10 -4 -5×10 -4 (m / s). i is the hydraulic gradient coefficient, its magnitude is equal to the specific laying slope of the culvert, only the numerical value is given, without units. A is the area of ​​the culvert's drainage cross-section (m²). 2 k is the negative pressure influence coefficient, the magnitude of which is determined based on the magnitude of the negative pressure influence received in the actual concealed pipe. Generally, it is in the range of 1.2-1.5, reflecting the multiple by which negative pressure increases the drainage volume of the concealed pipe. It has no unit.

[0065] Preferred, such as Figure 1As shown, the underground water collection system also includes a flushing subsystem. The flushing subsystem is connected to the relatively high end of the secondary delivery pipe 3 and is used to inject clean water into the secondary delivery pipe 3 when salt discharge stops. Specifically, in the salt discharge system of this invention, when the flow meter detects that the water flow rate in the primary delivery pipe 2 is lower than or equal to a predetermined value for a certain period of time (generally, the water flow rate in the primary delivery pipe 2 is 0, and the duration exceeds 30 minutes), salt discharge is considered to have stopped, the flow regulating valve is fully opened (the flow regulating valve switches to the fully open state), and the flushing subsystem starts operating, injecting clean water (the clean water source can be groundwater, surface water, recycled and emergency pool water, etc.) into the secondary delivery pipe 3. Then, the residual brine in the pipe is flushed away and replaced with clean water, effectively avoiding the salt crystallization and blockage problem caused by long-term evaporation of brine in the pipe. This achieves preventative and automated pipe maintenance, effectively improving the reliability of the salt discharge system of this invention, enabling it to maintain long-term stable operation for several years, and significantly reducing its maintenance costs. At the same time, the injected clean water can also clean the subsequent purification and diversion system and the ecological discharge pool system, removing excess salt residue (such as salt in the zeolite filter layer) from their structures, further improving the reliability of these systems and reducing their maintenance intervals.

[0066] After cleaning is completed, the flow regulating valve is completely closed, and the flushing subsystem continues to inject water until the secondary delivery pipe 3 is completely filled, maintaining positive pressure in the pipe and forming a clean water filling section (water seal), avoiding residual salt crystallization corrosion on the inner wall of the pipe, further reducing the corrosion rate of the pipe and valve, extending the equipment life, and enabling the salt discharge system of the present invention to quickly form a full pipe flow when started next time.

[0067] When the salt is discharged next time, the newly generated brine will flow into the cleaning water seal. The flow meter detects the continuous water flow, the flow regulating valve opens, and the salt discharge system of the present invention starts to operate. Under the action of the cleaning water seal in the secondary delivery pipe 3, the secondary delivery pipe 3 can immediately form a full pipe flow, quickly start up and generate a low-pressure environment, and quickly drain and discharge salt. It is not only highly reliable, but also has a fast response speed.

[0068] The monitoring and control system monitors the operation of the salt discharge system through a communication connection and adjusts the operation of the entire salt discharge system according to the actual situation to ensure the efficient operation of the entire salt discharge system.

[0069] like Figure 1 As shown, the water collection well system is located at the end of one or more pipe network subsystems and is used to precipitate, filter, and buffer the brine collected by the pipe network subsystems.

[0070] like Figure 4 As shown, the water collection well system includes a water collection well and a sedimentation chamber 9, a filtration chamber 10 and a buffer chamber 11 arranged in series in the water collection well.

[0071] like Figure 4 As shown, the collection well pool is a horizontally arranged concrete structure, which can be fully underground or semi-underground, preferably semi-underground. The sedimentation chamber 9 and the filtration chamber 10 are separated by a first partition wall 12, which has a first water outlet 13 for connecting the sedimentation chamber 9 and the filtration chamber 10. The filtration chamber 10 and the buffer chamber 11 are separated by a second partition wall 14, which has a second water outlet 15 for connecting the filtration chamber 10 and the buffer chamber 11.

[0072] The sedimentation chamber 9 is used to precipitate the brine collected by the underground pipe water collection system and initially remove mud and sand. The supernatant in the sedimentation chamber 9 enters the filter chamber 10 through the first water outlet 13.

[0073] Furthermore, the sedimentation zone has sufficient capacity to handle peak inflows, achieve effective solid-liquid separation, and prevent the filter chamber from clogging too quickly. The volume of the sedimentation chamber can be expressed by the formula: V s =Q max •t s Calculate, where V s Minimum volume required for the sedimentation zone (m³) 3 Q max This represents the maximum instantaneous flow rate (m³ / s) expected to enter the collection well. Its magnitude is determined comprehensively based on the sum of the theoretical drainage volumes Q of the underground pipes connected to the collection well, as well as local rainfall intensity and water level conditions. t s This is the shortest residence time (s) required for sediment in the water flow to settle in the sedimentation zone. Its value is determined based on the settling velocity of the sediment particles, and is generally taken as 600-1800 s (seconds) to ensure sufficient sedimentation.

[0074] The inlet of the sedimentation chamber 9 is located at the top of the sedimentation chamber 9 or at the top of the side wall of the sedimentation chamber 9 away from the first partition wall 12. A sludge hopper 16 is provided at the bottom of the sedimentation chamber 9 on the side away from the first partition wall 12.

[0075] The bottom of the sedimentation chamber 9 is inclined along the direction from the first partition wall 12 to the sludge hopper 16, so as to facilitate the deposition of sludge into the sludge hopper 16.

[0076] like Figure 4 As shown, preferably, the sedimentation chamber 9 is also equipped with a sludge scraper 17 and a sludge removal pipe 18, which are used to push the sludge deposited in the sedimentation chamber 9 into the sludge hopper 16 and discharge it from the sedimentation chamber 9. Of course, it is also possible to omit the sludge scraper 17 and other equipment, and use natural sedimentation and manual sludge removal.

[0077] like Figure 4As shown, the top of the sedimentation chamber 9 is also provided with a guide plate 19, which is used to guide the water flow entering from the inlet of the sedimentation chamber 9, so as to avoid the water flow speed being too fast, impacting the first water outlet 13 or causing the water flow to fail to settle sufficiently.

[0078] Filter chamber 10 is used for preliminary filtration of the water effluent from sedimentation chamber 9. In filter chamber 10, such as... Figure 4 As shown, the support layer 20, the main filter layer 21, and the adsorption layer 22 are arranged in order from bottom to top. The water effluent from the first water outlet 13 passes through the support layer 20, the main filter layer 21, and the adsorption layer 22 in sequence, and then enters the buffer chamber 11 through the second water outlet 15.

[0079] The support layer 20 is made of gravel with a particle size of 50-80 mm and a thickness of 150-200 mm. The main filter layer 21 is made of quartz sand with a particle size of 2-5 mm and a thickness of 300-400 mm. The filter layer is made of activated carbon or modified zeolite with a particle size of 1-2 mm and a thickness of 100-150 mm.

[0080] More preferably, a backwash pipe 23 is laid at the bottom of the support layer 20 for periodically backwashing the support layer 20, the main filter layer 21 and the adsorption layer 22 to further restore their filtration performance.

[0081] A partition 24 is also provided at the connection between the first water outlet 13 and the second water outlet 15 and the filter chamber 10 to prevent the filter material in the filter chamber 10 from being lost.

[0082] like Figure 4 As shown, the buffer chamber 11 is used to temporarily store the water from the second water outlet 15 and provide redundant space for the collection well pool, ensuring that the collection well pool has enough space to cope with the water level changes caused by tidal changes, and ensuring that the salt discharge system can operate normally when facing tides.

[0083] To ensure sufficient space within the collection well system to accommodate incoming water from the underground pipes during peak tidal levels, preventing system malfunction due to external water level rise, and to allow ample reaction time for triggering the submersible pump, the volume of the buffer chamber can be calculated using the following formula: V 缓 =ΔH•S•l. Where, V 缓 Minimum volume required for the buffer chamber (m³) 3 ΔH is the historical maximum tidal level difference in the coastal area (m), and S is the horizontal cross-sectional area of ​​the buffer cavity (m²). 2 k is the safety factor, ranging from 1.5 to 2.0, used to cope with unpredictable extreme weather such as extreme tides or heavy rainfall.

[0084] like Figure 4As shown, the second water outlet 15 is located at the top of the second partition wall 14 to ensure drainage even when the water level in the buffer chamber 11 is high. A water level monitor 25 is installed in the buffer chamber 11 to detect the water level. The water level monitor 25 is communicatively connected to the monitoring and control system.

[0085] In this invention, the coordinated operation of the underground water collection pipe system 1 and the water collection well system significantly reduces the possibility of the desalination system being blocked by silt, thus greatly improving the reliability of the desalination system. Simultaneously, the buffer chamber 11 in the water collection well provides good resistance to tides. During tides, the change in water level in the buffer chamber 11 indicates that the desalination system can normally discharge salt, and this can be regulated through monitoring and control, demonstrating good tidal adaptability.

[0086] The effluent from the collection well enters the purification system under the influence of gravity.

[0087] The purification and treatment system comprises a purification and diversion system and an ecological discharge pond system connected in sequence. The purification and diversion system performs secondary filtration on the brine transported by the collection system, reducing its salt content and diverting it according to the salt concentration of the purified brine. The ecological discharge pond system receives the brine diverted by the purification and diversion system and discharges it ecologically and / or reuses it.

[0088] The ecological discharge pond system includes an ecological discharge pond for receiving brine with a salt concentration below a predetermined threshold and a recovery and emergency pond for receiving brine with a salt concentration above a predetermined threshold. For example... Figure 6 As shown, in the ecological discharge pond, an ecological salt filter layer 32 and a drainage pipe 34 are sequentially arranged along the direction of salt water flow. Depending on the local soil conditions and design requirements, the drainage pipe 34 can be connected to the groundwater layer 33 or to a drainage ditch (which can be an artificially excavated drainage ditch or a natural waterway such as a river or stream) to directly discharge the water into the salt discharge system, thus avoiding the impact of the clay layer on the drainage effect of the salt discharge system during natural seepage.

[0089] like Figure 1As shown, the coastal saline-alkali land underground pipe-collection well salt drainage system (hereinafter referred to as the salt drainage system) of the present invention, through the cooperation of a water collection system, a purification and diversion system, and an ecological discharge pond system, addresses the issue of different treatment paths for different salt concentrations in the collected brine, as proposed by the present invention. This allows for the safe discharge of compliant brine, avoiding the discharge of large amounts of high-concentration brine into the ground and preventing secondary pollution and salt backflow. Furthermore, it enables the resource recovery of high-concentration brine, reducing environmental pressure. The recovered salt crystals can also be used as de-icing agents or industrial raw materials, recovering some funds and reducing the budget pressure of the salt drainage system during operation and maintenance. Simultaneously, since the ecological discharge pond of the present invention is also equipped with a drainage pipe 34 that directly reaches the groundwater layer 33 or a drainage ditch, it can directly guide the brine flowing into the ecological discharge pond into the groundwater layer 33 or surface water, giving the salt drainage system a faster drainage speed and effectively avoiding the problem of precipitation difficulties caused by clay layers. After passing through the ecological salt filter layer 32, the salt content of the brine in the ecological discharge pond will be further reduced, which can further reduce potential secondary pollution and other problems.

[0090] The water collection system, purification and diversion system, and ecological discharge pond system of this invention work together to form a system engineering project that integrates salt collection, transportation, purification, differentiated treatment, and ecological synergy. It can achieve high drainage efficiency and salt removal effect while ensuring that the operating cost of the entire salt removal system is low and relatively environmentally friendly. Its drainage efficiency is also less affected by soil quality and is not prone to secondary pollution.

[0091] Preferred, such as Figure 5 As shown, the purification and diversion system includes a secondary filtration chamber 26 and a diversion valve 27 connected in sequence. The inlet of the secondary filtration chamber 26 is connected to the water collection system. Inside the secondary filtration chamber 26, a zeolite adsorption layer 28, a submersible pump 29, and a water quality monitoring unit 30 are arranged in sequence along the brine flow direction. One secondary filtration chamber 26 can be connected to one or more water collection wells, depending on the size of the purification and diversion system. Preferably, the secondary filtration chambers 26 correspond one-to-one with the pipe network subsystem, and the diversion valves 27 correspond one-to-one with the secondary filtration chambers 26, ensuring the purification effect of the secondary filtration chambers 26 and the diversion effect of the diversion valves 27.

[0092] Submersible pump 29 is connected to an external drainage ditch or a recovery and emergency pool, preferably to the recovery and emergency pool. When the water level monitor 25 detects that the water level in the emergency buffer pool exceeds the warning level (the warning level is determined based on the volume of the emergency buffer pool and local hydrological conditions) and remains high, it indicates that due to the influence of tides / heavy rainfall / other conditions, the drainage speed of subsequent treatment systems is slow and cannot effectively discharge the brine in the collection well pool, which may affect the normal operation of the desalination system. At this time, in order to avoid problems such as seawater backflow / brine seepage after diversion, the brine in the secondary filtration chamber 26 can be quickly extracted by submersible pump 29 and discharged in an emergency (further ecological purification can be disregarded in an emergency, prioritizing the normal water collection and operation of the desalination system) to ensure normal desalination. If necessary, the flow can also be cut off or significantly reduced by controlling the diversion valve 27 to further prevent problems such as seawater backflow and allow the water in the recovery and emergency pool and the ecological recovery well pool to seep down. When the water level monitoring instrument 25 detects that the water level in the emergency buffer pool is lower than the safe water level, the salt discharge system resumes normal operation.

[0093] Furthermore, due to the presence of an ecological discharge system, the outlet of the water collection system of this invention is not directly connected to the outside. When the tide comes, the external water level is unlikely to affect the water collection system through the ecological discharge system, and it can still drain water normally, thus exhibiting good tidal adaptability.

[0094] Furthermore, since the submersible pump 29 is located behind the zeolite filter layer, it does not come into direct contact with the high-salt environment and is less prone to malfunction.

[0095] Because submersible pumps need to overcome significant static pressure differences and pipeline resistance, their head is determined by the formula: H = H1 + H2 + H3 + H4, where H is the required design head of the submersible pump (m). H1 is the height difference between the warning water level in the sump and the highest water level in the external water body (m). H3 is the local head loss in the pipeline (m), generally H3 = (0.1-0.2)·H2. H4 is the safety redundancy head (m), typically taken as 0.5-1.0m. H2 is the friction head loss along the pipeline (m), determined by the formula: H2 = λ·(L / D)·(υ). 2 The value is calculated as / 2g). Where λ is the pipe friction coefficient, determined based on the pipe material (e.g., 0.01-0.02 for PE pipes), L is the pipe length (m) from the submersible pump to its outlet, D is the pipe inner diameter (m), υ is the water velocity in the pipe (m / s), typically taken as 0.8-1.2 m / s, and g is the acceleration due to gravity (9.81 m / s²). 2 Ensure the submersible pump has sufficient head.

[0096] The zeolite in the zeolite filter layer is modified and activated zeolite. The brine flows through the zeolite filter layer for a distance of no less than 1.5m to ensure the contact area and reaction time between the brine and the modified zeolite. This ensures the efficient and stable adsorption and removal of cations such as sodium ions from the brine by the zeolite filter layer, reducing the sodium adsorption ratio of the brine after passing through the zeolite filter layer and minimizing its environmental pollution.

[0097] Preferably, the zeolite filter layer is S-shaped, and the secondary filtration chamber 26 is provided with an S-shaped flow channel. The zeolite filter layer is disposed in the S-shaped flow channel, and the cross-sectional area of ​​the flow channel is determined according to the expected amount of brine to be treated, preferably not less than 100 cm². 2 By designing an S-shaped flow channel, the overall length of the secondary filter chamber 26 is shortened.

[0098] The water quality monitoring unit 30 is used to monitor the salt concentration of the brine after passing through the zeolite adsorption layer 28. The outlet of the secondary filtration chamber 26 is connected to the diversion valve 27, which diverts the brine according to the monitoring results of the water quality monitoring unit. Both the water quality monitoring unit 30 and the diversion valve 27 are communicatively connected to the monitoring and control system.

[0099] Preferably, the water quality monitoring unit 30 is a conductivity sensor, and the diversion valve 27 is a multi-way valve (electric multi-way valve).

[0100] Preferably, when the water quality monitoring unit 30 detects that the conductivity of the brine is greater than 5 mS / cm, it determines that the brine has a high salt content and transports it to the recovery and emergency pool through the diversion valve 27. When the water quality monitoring unit 30 detects that the conductivity of the brine is less than or equal to 5 mS / cm, it transports the brine to the ecological discharge pool through the diversion valve 27. When the diversion valve 27 responds to the monitoring results of the water quality monitoring unit 30, a corresponding delay time can be set according to the distance between the brine and the water quality monitoring unit 30 to ensure accurate delivery of the brine.

[0101] Meanwhile, this monitoring method can also effectively deal with problems such as seawater backflow. When the water quality monitoring unit 30 detects an abnormal increase in the conductivity of the brine, which may indicate seawater backflow, it can immediately shut off the connection between the secondary filtration chamber 26 and the ecological discharge pool, and use the submersible pump 29 to divert the flow to the recovery and emergency pool.

[0102] The secondary filtration chamber 26 can be set at an angle or horizontally, and the brine inside it will move towards the diversion valve 27 under the push of the brine in the water collection system.

[0103] The brine passing through the diversion valve 27 can flow into the ecological discharge pool or the recovery and emergency pool via a water pump or under gravity. In this case, the ecological discharge pool or the recovery and emergency pool should be relatively deep to ensure natural water flow. Of course, if it is inconvenient to construct a deep ecological discharge pool or the recovery and emergency pool, a water pump can be used for diversion. A small number of water pumps will not significantly increase maintenance costs and can reduce construction requirements to some extent.

[0104] Preferred, such as Figure 6 As shown, the ecological discharge pond includes a pond body 31 and an ecological salt filter layer 32 and a drainage pipe 34 arranged sequentially in the direction of water flow within the pond body.

[0105] According to design requirements, pool body 31 is a semi-underground structure (i.e., part of the structure is built below the ground surface and part of the structure is exposed on the ground surface) or an above-ground structure, with a roof 39 on top.

[0106] When pool 31 is a semi-underground structure, such as Figure 6 As shown, preferably, the brine passing through the diversion valve 27 flows into the ecological discharge pond under gravity, and the drain pipe 34 is connected to the groundwater layer 33. When the pond body 31 is an above-ground structure, as... Figure 7 As shown, preferably, a water pump is installed between the diversion valve 27 and the pool body 31. The brine passing through the diversion valve 27 flows into the ecological discharge pool under the action of the water pump, and the drain pipe 33 is connected to the drainage ditch.

[0107] A semi-underground structure reduces the complexity of the desalination system and minimizes mechanical components (such as pumps). Only a deeper ecological drainage pond is needed, allowing drainage to proceed under gravity. However, this structure requires a relatively high groundwater level and is susceptible to tidal influences. An above-ground structure uses pumps to direct water from a diversion valve into the above-ground ecological drainage pond. Its drainage efficiency is unaffected by tides and can be continuous and efficient, but it requires additional pumps for water delivery. The specific solution should be chosen based on actual geological and hydrological conditions, prioritizing efficient drainage.

[0108] Preferred, such as Figure 6-7 As shown, the ecological salt-filtering layer 32 and the drain pipe 34 are located at the bottom of the pool body 31. The drain pipe 34 includes a filtration section and a conveying section. The ecological salt-filtering layer 32 covers the outer periphery of the pipe wall of the filtration section. In the direction away from the outer periphery of the drain pipe 34 (in the opposite direction of water flow), the ecological salt-filtering layer 32 sequentially includes a fine sand filter layer 35, a bacterial-loaded ceramic particle filter layer 36, a coarse sand filter layer 37, and a gravel filter layer 38. The thickness of each filter layer is 150-300 mm. The filtration section of the drain pipe 34 is provided with filter holes with an opening rate of 15-20%.

[0109] like Figure 6-7 As shown, the conveying section passes through the bottom of the pool body 31 and connects to the groundwater layer 33 or the drainage ditch, preferably to the groundwater layer 33. After the brine enters the ecological discharge pool, it needs to pass through the gravel filter layer 38, the coarse sand filter layer 37, the bacteria-laden ceramic particle filter layer 36, and the fine sand filter layer 35 in sequence. Then, it enters the filter section of the drain pipe 34 through the filter holes, flows into the conveying section, and then flows into the groundwater layer 33 or the drainage ditch to complete the discharge.

[0110] Among them, a physical filtration barrier is formed by fine sand, ceramsite, coarse sand and gravel to filter impurities and reduce the salt content of the brine entering the groundwater layer 33 or drainage ditch.

[0111] Preferably, the particle size of the bacterial-loaded ceramic granule layer is 5-10 mm, and the porosity is not less than 30%. The bacterial-loaded ceramic granule layer is loaded with salt-tolerant bacteria (such as Pseudomonas, Bacillus subtilis, and Bacillus licheniformis) for removing organic pollutants from brine. The salt-tolerant bacteria loaded on the bacterial-loaded ceramic granules can be a single bacterial group or a complex bacterial group composed of multiple bacteria to ensure the synergistic degradation of multiple organic pollutants.

[0112] The bacterial-loaded ceramic particles have a porous structure with a porosity of not less than 30%, ensuring effective bacterial loading. During loading, a biofilm loading method is used. Selected salt-tolerant bacteria, culture medium, and bacterial-loaded ceramic particles are mixed and cultured for a certain period. Loading is complete once the salt-tolerant bacteria have multiplied extensively within the ceramic particles and produced a stable biofilm. The salt-tolerant bacteria, in conjunction with their secreted biofilm, effectively degrade dissolved organic matter in the brine, significantly reducing the chemical oxygen demand (COD) and biological oxygen demand (BOD) of the brine, achieving deep purification of the discharged brine. Simultaneously, the activity of the microorganisms also produces organic acids and other substances, effectively preventing the gravel filter layer 38, coarse sand filter layer 37, bacterial-loaded ceramic particle filter layer 36, and fine sand filter layer 35 from caking due to prolonged exposure to a saline-alkali environment. This avoids loss of filtration effectiveness or decreased permeability, leading to brine accumulation and further improving the reliability of the salt discharge system of this invention, ensuring its long-term maintenance-free operation.

[0113] More preferably, the fine sand filter layer 35 has a particle size of 0.5-1 mm and a thickness of 100-150 mm; the coarse sand filter layer 37 has a particle size of 2-5 mm and a thickness of 200-300 mm; and the gravel filter layer 38 has a particle size of 10-20 mm and a thickness of 150-200 mm. All the fine sand, coarse sand, and gravel have been washed and screened, and the mud content does not exceed 3 wt%. Different filter layers can be separated and fixed using perforated plates. Alternatively, a longer flow channel structure can be configured and the filter layers filled sequentially, such as a U-shaped flow channel structure, but this may affect the drainage efficiency.

[0114] The filter holes on the drain pipe 34 should have a diameter smaller than that of fine sand particles, allowing water to pass through while preventing filter media loss. Additionally, the drain pipe 34 should be made of high-strength pipe material capable of withstanding geological pressure (such as stainless steel pipe, high-strength PVC + carbon fiber pipe, etc.), and its internal support frame can be further installed to prevent pipe deformation.

[0115] Preferably, the pool body 31 is also lined with an aging-resistant geomembrane (such as a high-density polyethylene geomembrane), and the geomembranes are connected by hot-melt welding, with the welding strength not less than 80% of the strength of the geomembrane parent material, to ensure the seepage prevention effect.

[0116] Preferably, the ecological discharge pond is equipped with at least one ecological salt-filtering layer 32 and one drain pipe 34, and is connected to at least one secondary filtration chamber 26 (via a diversion valve 27). More preferably, in the ecological discharge pond, the pond body 31 is made of cast concrete, the thickness of the concrete on the side walls and bottom of the pond body 31 is not less than 200mm, preferably 200-300mm, the length of the pond body 31 is 3-5m, the width is 2-4m, and the depth is 2-3m, the diameter of the drain pipe 34 is 200-300mm, and the pond body 31 is equipped with one ecological salt-filtering layer 32 and one drain pipe 34, and is connected to 1-3 secondary filtration chambers 26.

[0117] Preferred, such as Figure 6 As shown, the top cover 39 is provided with several planting holes 40, and deep-rooted salt-tolerant plants are planted in the planting holes 40, including at least one of the following: Suaeda salsa, mangrove, Suaeda salsa, reed, Salicornia glutinosa, Deer antler velvet, Salix babylonica, and Elaeagnus angustifolia. Among them, the salt-tolerant plants planted on the ecological discharge pond have relatively long root systems. Their roots can penetrate into the pond through the planting holes 40 and enter the salt water in the pond body 31. Through transpiration, they help to lower the water level and reduce the salt content of the salt water in the pond body 31 (the salt-tolerant plants can absorb salt water through their roots and transfer the salt to their leaves or other parts for excretion, thus reducing the salt content of the salt water in the pond body 12 to a certain extent). At the same time, and importantly, the roots of these plants can attach to and penetrate into the filter layer outside the drain pipe 34, working together with microorganisms (mainly bacteria attached to the bacterial-carrying ceramic particles) to form micropores. This improves the structure of the filter layer, further preventing problems such as caking, ensuring the continuous filtration capacity of the multiple filter layers in the well tank of this invention, improving reliability, and reducing maintenance costs. Furthermore, the plant roots can also provide effective attachment points for microorganisms, facilitating their further reproduction.

[0118] Preferred, such as Figure 6As shown, a hanging cage 41 is connected to the bottom of the top cover 39, and the hanging cage 41 is filled with soil conditioner 42. When the soil conditioner 42 comes into contact with the brine, it undergoes continuous ion exchange, further reducing the sodium ion content in the brine while releasing a large number of active ingredients. These active ingredients (such as calcium ions and magnesium ions) can be released along with the brine into the groundwater layer 33 or drainage ditch (preferably into the groundwater layer 33, where its diffusion effect is better), and then diffuse into the surrounding soil, improving water quality, reducing soil alkalinity, reducing the possibility of soil salinization, and accelerating the ecological restoration process of saline-alkali land. After a certain period of use, the hanging cage 41 needs to be removed and replaced with new soil conditioner 42 to ensure the soil improvement effect.

[0119] Preferably, the soil conditioner 42 includes at least one of crushed brick, fly ash, desulfurized gypsum, phosphogypsum, and lime. More preferably, it is crushed brick and / or fly ash, which, as construction / industrial waste, achieve soil improvement while also being relatively inexpensive.

[0120] More preferably, a booster pump is also provided between the ecological discharge pond and the diversion valve 27, and the inlet of the ecological discharge pond is higher than the ground surface. If necessary, in areas where seawater frequently backflows and the seawater level is relatively high compared to the ground surface, the booster pump can be used to transport brine to the ecological discharge pond. By maintaining a high water level in the pond 31 through the higher inlet, the drainage power of the ecological discharge pond can be improved. At the same time, the higher inlet can further avoid problems such as backflow that may be caused by gravity drainage.

[0121] Preferably, the recovery and emergency pool includes an emergency buffer pool for temporarily storing brine with a salt concentration higher than a predetermined threshold and water from the submersible pump 29, connected in sequence, and an evaporation crystallization pool 43 for brine evaporation and crystallization. After the diversion valve 27 or the submersible pump 29 discharges brine into the recovery and emergency pool, the brine will be temporarily stored in the emergency buffer pool first, and then gradually released into the evaporation crystallization pool 43 for crystallization. This avoids excessive brine in the evaporation crystallization pool 43, preventing it from becoming too dense for crystallization, and also avoids direct discharge of the brine to the outside. Of course, if there is no concern about the collected brine contaminating the outside environment, or if the emergency buffer pool and the evaporation crystallization pool 43 are completely full (which is a very small probability that may occur under severe weather conditions such as strong typhoons, when heavy rainfall and high water levels combine), the water from the submersible pump 29 can also be directly discharged into a drainage ditch.

[0122] Preferably, the emergency buffer pool is a semi-underground or underground structure (i.e., emergency buffer pools are generally built underground) to ensure smooth water flow. The interior of the emergency buffer pool is also lined with an aging-resistant geomembrane with a thickness of not less than 1.5 mm. The geomembranes are joined by hot-melt welding, with a weld strength of not less than 80% of the strength of the parent material. Preferably, the aging-resistant geomembrane has an aging resistance of not less than 50 years for outdoor use, ensuring its seepage prevention and aging resistance in high-salt environments.

[0123] Preferably, the evaporation crystallization tank 43 is an above-ground or semi-underground structure. To ensure its evaporation crystallization effect, such as... Figure 7 As shown, a ground-level structure is preferred. When the evaporation crystallization tank 43 adopts a ground-level structure, a water pump can also be used to connect the emergency buffer tank and the evaporation crystallization tank 43, pumping the brine from the emergency buffer tank to the evaporation crystallization tank 43. In this case, although a water pump is used, it is generally built above ground and only used for the transfer of small amounts of brine (especially when using a ground-level ecological discharge well), so problems are less likely to occur, and the maintenance cost is also lower. Multiple emergency buffer tanks can be connected to the same evaporation crystallization tank 43 simultaneously.

[0124] The crystalline salt precipitated in evaporation crystallization tank 43 can be collected periodically. After passing the test, it can be used as a snow melting agent or industrial raw material (such as raw material for chlor-alkali industry) for resource utilization and capital recovery.

[0125] Of course, a deeper semi-underground evaporation crystallization tank 43 can also be set up, and gravity (which requires the installation of water valves and other structures) can be used for transfer.

[0126] The top of the evaporation crystallization tank 43 is an open structure and is covered with a heat-insulating film 44 to increase the temperature inside the evaporation crystallization tank 43. The heat-insulating film 44 creates a greenhouse inside the evaporation crystallization tank 43, which accelerates the evaporation of water.

[0127] More preferably, the side of the evaporation crystallization tank 43 is provided with a water collection trough 45 and a water collection tank connected in sequence. The heat insulation membrane 44 is inclined, and its bottom end is located in the water collection trough 45. The water evaporated in the evaporation crystallization tank 43 condenses on the heat insulation membrane 44 and slides into the water collection trough 45 along the inclination angle of the heat insulation membrane 44, and then flows into the water collection tank, avoiding the backflow of evaporated water or waste of water resources. The water in the water collection tank can be directly discharged or used for the reserve water of the flushing subsystem (i.e., the above-mentioned recycled and emergency pool recycled water), reducing the water demand of the desalination system of the present invention.

[0128] In addition, since coastal areas have abundant sunshine with virtually no obstructions, structures such as reflectors and tube-screen evaporators can be installed to collect and better utilize solar energy, assisting in evaporation and concentration and accelerating the evaporation and crystallization rate of brine.

[0129] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0130] Example 1

[0131] This embodiment provides a subsurface pipe-collection well salt drainage system for coastal saline-alkali land. The system is applied to a 100-mu (approximately 6.7 hectares) coastal reclaimed moderately saline-alkali land improvement project. The soil is chloride-saline soil, with an average salt content of 4.5 g / kg in the 0-30 cm soil layer and a pH of 8.5. Surveys show that the groundwater level is significantly affected by tides, fluctuating between 1.5 m and 2.5 m in depth. Discontinuous clay lenses are present 1.2 m below the soil surface.

[0132] The desalination system includes: a water collection system (consisting of a submerged pipe water collection system and a water collection well system), a purification and diversion system, an ecological discharge pool system, and a monitoring and control system.

[0133] The underground water collection system employs a herringbone layout: a high-strength PVC+carbon fiber composite underground water collection pipe 1 with a diameter (DN) of 160mm is laid at a depth of 1.0 meter underground at a slope of 0.4%. The outside of the underground water collection pipe 1 is successively wrapped with a geotextile filter layer and a straw layer, with removable stainless steel filter screens (0.8mm aperture) embedded in its permeable pores. All underground water collection pipes 1 (spaced 10 meters apart) converge into a DN200 primary delivery pipe 2; multiple primary delivery pipes 2 then converge into a DN250 secondary delivery pipe 3. On the secondary delivery pipe 3, a set of pressure sensors and one-way valves are installed every 50 meters along the water flow direction. The pressure sensors have a range of 0-0.5MPa, and the opening and closing thresholds are set to 0.3MPa and 0.1MPa, respectively. The end of the secondary delivery pipe 3 is connected to a siphon pipe 8 with a vertical drop of 0.8 meters.

[0134] The collection well system is constructed at the end of the pipeline network and is an underground reinforced concrete structure. Its walls are reinforced with a composite structure of concrete and fiberglass reinforced plastic (FRP). The interior of the well is divided into a sedimentation chamber 9, a filtration chamber 10, and a buffer chamber 11, arranged in series. The sedimentation chamber 9 has a sludge hopper 16 and a scraper 17 at its bottom. The filtration chamber 10 is filled from bottom to top with a gravel support layer 20 (50-80mm particle size, 180mm thick), a quartz sand main filter layer 21 (2-5mm particle size, 350mm thick), and an activated carbon adsorption layer 22 (1-2mm particle size, 120mm thick), with a backflushing pipe 23 at the bottom. The buffer chamber 11 is equipped with an immersion-type level sensor for monitoring the water level.

[0135] In the purification and diversion system, the secondary filtration chamber 26 is an underground concrete structure. After entering the chamber, the brine first flows through the zeolite adsorption layer 28, which has a total flow channel length of 2.0 meters and is arranged in an S-shape, and then flows through the online conductivity sensor. The sensor data is transmitted to the monitoring and control system in real time. When the reading exceeds the set threshold of 5.0 mS / cm, the control system commands the diversion valve 27 (electric three-way valve) to operate, diverting the high-salinity brine to the recovery and emergency pool. The monitoring and control system is connected to local tidal forecast information. When a spring tide is predicted and the water level in the buffer chamber 11 remains high, the system can enter a standby state in advance and can automatically trigger emergency diversion when the influent salinity rises abnormally (such as an EC value that suddenly exceeds 8 g / L).

[0136] In the ecological discharge pond system, the ecological discharge pond is a semi-underground structure. The pond top cover 39 has reserved planting holes 40 for cultivating salt-tolerant plants (such as Suaeda salsa), and hanging cages 41 containing soil conditioner 42 are suspended from it. The recycling and emergency pond includes an underground emergency buffer pond and an above-ground evaporation crystallization pond 43.

[0137] After 24 months of continuous operation, the system demonstrated outstanding overall performance. During operation, the collection well system effectively removed over 85% of suspended sediment from the incoming water, and the buffer chamber 11 effectively mitigated water level fluctuations caused by multiple tides. The peak discharge flow rate remained stable at 1.3 m³ / h. 3 The average salinity of the 0-30 cm soil layer decreased from 4.5 g / kg to 1.3 g / kg per hour. Approximately 80% of the brine was purified to meet standards and safely discharged through an ecological discharge pond. No abnormal increase in salinity was observed in the surrounding ditches after discharge. The remaining 20% ​​of the brine was diverted to recovery and emergency ponds, recovering approximately 1.8 tons of crystallized salt annually. The tidal pressure balancing valve of the underground pipe system automatically opened and closed multiple times during operation, effectively mitigating pressure fluctuations within the pipes. The flushing subsystem operated regularly, and the entire system experienced no blockages, demonstrating excellent reliability and environmental adaptability.

[0138] Example 2

[0139] This embodiment provides a coastal saline-alkali land underground pipe-collection well salt drainage system. The salt drainage system is used to treat 100 acres of severely saline-alkali land that is heavily affected by tides. The average soil salt content is 7.2 g / kg, the pH value is 8.8, the groundwater level can be as shallow as 0.8 m, the soil texture is heavy and the permeability is poor.

[0140] Based on the actual situation, the desalination system was specifically enhanced based on Example 1. In the underground water collection system, the spacing between the underground water collection pipes 1 was increased to 7 meters, and more low-pressure node cavities were added to the secondary delivery pipe 3 to improve water collection efficiency in heavy clay soil. In the purification and diversion system, the flow channel length of the zeolite adsorption layer 28 was increased to 3.0 meters to cope with higher initial salinity. The ecological discharge pond is an above-ground structure, and a water pump is used to transport the water from the purification and diversion system to the ecological discharge pond.

[0141] After 18 months of stable operation, despite frequent fluctuations in the water level of the external ditches due to tidal influences, the internal hydraulic state of the drainage system remained stable thanks to the regulating effect of the buffer chamber 11 in the collection well and the subsequent diversion and ecological discharge systems, preventing any seawater backflow. Soil salinity decreased to 2.5 g / kg. Due to the initial high salinity, 35% of the brine was diverted to the recovery and emergency pools, resulting in an annual recovery of 4.8 tons of crystalline salt, demonstrating significant benefits. The backwashing structure of the flushing subsystem and the filtration chamber 10 in the collection well operates automatically according to a preset cycle, effectively maintaining filtration performance. The sludge scraper 17 in the sedimentation chamber 9 reduces the frequency of manual sludge removal. The entire system exhibits low maintenance requirements and high operational stability even in harsh environments.

[0142] In summary, the present invention can solve the technical problems existing in the prior art, such as the salt drainage system being prone to secondary pollution, poor adaptability to coastal areas, poor drainage efficiency in the complex environment of coastal saline-alkali land, easy pipe blockage, and the need for frequent maintenance.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coastal saline-alkali land subsurface pipe-catch well pond salt discharge system, characterized in that, The application relates to a monitoring and regulating system and a water collecting system and a purification treatment system connected in sequence. The water collecting system comprises a buried pipe water collecting system and a water collecting well pool system. The monitoring and regulating system is used for detecting the running state of other systems and regulating; the buried pipe water collecting system is used for collecting salt water in soil and conveying the salt water to the water collecting well pool system; the water collecting well pool system is used for depositing, filtering and buffering the salt water conveyed by the buried pipe water collecting system; and the purification treatment system is used for secondary filtering and safe discharging of the water discharged by the water collecting well pool system. The buried pipe water collecting system comprises a plurality of pipe network subsystems, and the water collecting well pool system is arranged at the end of one or more pipe network subsystems; the water collecting well pool system comprises a depositing cavity (9) for depositing silt in the water discharged by the buried pipe water collecting system, a filtering cavity (10) for preliminarily filtering the water discharged by the depositing cavity (9), and a buffering cavity (11) for buffering the water discharged by the filtering cavity (10) and providing a redundant space for tidal level change. The purification treatment system comprises a purification and shunting system for secondary filtering of the salt water conveyed by the water collecting system, reducing the salt content of the salt water and shunting the salt water according to the salt concentration of the salt water after secondary filtering, and an ecological discharging system for receiving the salt water generated by the purification and shunting system and discharging and / or reusing the salt water in an ecological way.

2. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 1, characterized in that, The ecological discharging system comprises an ecological discharging pool for receiving salt water with a salt concentration lower than a predetermined threshold and a recovery and emergency pool for receiving salt water with a salt concentration higher than the predetermined threshold; the ecological discharging pool is sequentially provided with an ecological salt filtering layer (32) and a drain pipe (34) along the water flow direction, and the drain pipe (34) is communicated with a groundwater layer (33) or a drain channel. A water level height monitor (25) is arranged in the buffering cavity (11); the purification and shunting system comprises a submersible pump (29) for quickly discharging the salt water in the purification and shunting system into the recovery and emergency pool of the ecological discharging system when the water level in the buffering cavity (11) is too high. Each pipe network subsystem comprises a plurality of water collecting buried pipes (1), a plurality of first conveying pipes (2) and a second conveying pipe (3); a plurality of water seepage openings are arranged on the pipe wall of the water collecting buried pipe (1); the water collecting buried pipe (1), the first conveying pipe (2) and the second conveying pipe (3) are all arranged in an inclined mode, and the gradient is 0.2%-0.6%; a plurality of water collecting buried pipes (1) are connected with one first conveying pipe (2); a plurality of first conveying pipes (2) are connected with the second conveying pipe (3). A plurality of low-pressure node cavities for enhancing the low-pressure environment in the first conveying pipe (2) are arranged in the second conveying pipe (3); along the salt water flow direction in the second conveying pipe (3), the low-pressure node cavities comprise a contraction cone pipe (4), a throttling pipe (5) and a diffusion cone pipe (6); the first conveying pipe (2) is connected to the side wall of the contraction cone pipe or the throttling pipe.

3. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 1, characterized in that, ​ ​ 4. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 3, characterized in that, The water collecting underground pipe (1) has an air vent end and a water outlet end; the water outlet end is connected with the first conveying pipe (2); the air vent end is provided with an air vent pipe (7) which is higher than the ground and has an outlet communicating with the outside; the diameter of the outlet of the air vent pipe (7) is not more than 20% of the diameter of the water collecting underground pipe (1); The outlet of the first conveying pipe (2) is provided with a flow meter for monitoring the flow of the brine output by the first conveying pipe (2); the outlet of the second conveying pipe (3) is provided with a flow regulating valve; the flow meter and the flow regulating valve are both in communication connection with the monitoring and control system; the water outlet of the second conveying pipe (3) is connected with the water collecting well pool system.

5. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 3, characterized in that, The water collecting underground pipe system further comprises a flushing sub-system which is connected with the end of the second conveying pipe (3) higher than the other end and is used for injecting clean water into the second conveying pipe (3).

6. The underdrain-catchwell pond salt removal system of coastal saline soil according to claim 2, wherein The purification and distribution system comprises a secondary filtering bin (26) and a distribution valve (27); the water inlet of the secondary filtering bin (26) is connected with the water collecting well pool system; the secondary filtering bin (26) is provided with, in sequence along the flow direction of the brine, a zeolite adsorption layer (28), a submersible pump (29) and a water quality monitoring unit (30); the water quality monitoring unit (30) is used for monitoring the salt concentration of the brine after passing through the zeolite adsorption layer (28); the water outlet of the secondary filtering bin (26) is connected with the distribution valve (27); the distribution valve (27) distributes the brine according to the monitoring result of the water quality monitoring unit; the water quality monitoring unit (30) and the distribution valve (27) are both in communication connection with the monitoring and control system.

7. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 2, wherein The ecological discharge pool comprises a pool body (31); the pool body (31) is of an above-ground structure or a semi-underground structure and is provided at the top with a top cover (39); the ecological salt filter layer (32) and the drain pipe (34) are arranged at the bottom of the pool body (31).

8. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 7, characterized in that, In the direction of water flow, the ecological salt filter layer (32) comprises, in sequence, a gravel filter layer (38), a coarse sand filter layer (37), a bacteria-loaded ceramic filter layer (36) and a fine sand filter layer (35); the drain pipe (34) comprises a filtering section and a conveying section; the filtering section is arranged in the pool body (31) and the conveying section passes through the pool body (31) and communicates with a drain channel or an underground water layer (33); the filtering section of the drain pipe (34) is provided with filtering holes with an opening rate of 15-20%; the diameter of the filtering holes is smaller than the particle size of the fine sand in the fine sand filter layer (35); The particle size of the ceramic in the bacteria-loaded ceramic layer is 5-10 mm and the porosity is not less than 30%; the bacteria-loaded ceramic layer is loaded with salt-tolerant bacteria for removing organic pollutants in the brine.

9. The underdrain-catchwell pond salt discharge system of coastal saline soil according to claim 7, wherein The top cover (39) is provided with a plurality of planting holes (40), and deep-rooted salt-tolerant plants are planted in the planting holes (40), wherein the deep-rooted salt-tolerant plants are at least one of Suaeda salsa, mangrove, Artemisia halodendron, Phragmites australis, Salicornia, Salix, red willow, strange willow and Russian olive; the bottom of the top cover (39) is further connected with a hanging cage (41), and the hanging cage (41) is filled with a soil conditioner (42); the soil conditioner (42) comprises at least one of broken bricks, fly ash, desulfurization gypsum, phosphogypsum and lime.

10. The underdrain-catchwell pond salt removal system of coastal saline soil according to claim 2, wherein The recovery and emergency pool comprises an emergency buffer pool and an evaporation crystallization pool (43) connected in sequence, and the emergency buffer pool is used for temporarily storing brine with a salt concentration higher than a predetermined threshold; the top of the evaporation crystallization pool (43) is covered with a heat preservation film (44) for increasing the temperature in the evaporation crystallization pool (43); and the emergency buffer pool further receives the brine discharged from the buffer cavity (11).

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