A salt and alkali land desalination and recharge coordination system under a sunlight greenhouse shed

Abstract

The present application relates to saline-alkali soil technical field, disclose a kind of for solar greenhouse greenhouse under saline-alkali soil's salt removal desalination recharging coordination system, the system includes: intelligent monitoring and control system, salt removal collection and raw water regulation and storage system, brackish water pretreatment desalination and tail water disposal system, photovoltaic power supply and recharging salt control system, salt removal collection and raw water regulation and storage system include salt removal branch and water collecting well, salt removal branch is laid in saline-alkali soil ploughing layer below, collect brackish water in soil, water collecting well temporarily stores brackish water;Intelligent monitoring and control system meets the starting condition of brackish water pretreatment desalination and tail water disposal system and outputs starting instruction;Brackish water pretreatment desalination and tail water disposal system are used to receive starting instruction when, to brackish water is filtered, membrane desalination treatment;Photovoltaic power supply and recharging salt control system are used for power supply, fresh water is transported to greenhouse irrigation system, and the present application each system is operated in coordination, forms salt removal-desalination-recharging closed loop operation system, realizes water resource recycling.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land improvement technology, specifically to a combined system for desalination, salt removal, and recharge in saline-alkali land under solar greenhouses. Background Technology

[0002] Saline-alkali land, as an important reserve of arable land, has a high content of soluble salts in its soil, a high degree of groundwater mineralization, and strong regional evaporation, which makes it easy for soil salts to accumulate on the surface, seriously restricting agricultural production and sustainable land use.

[0003] Against this backdrop, underground drainage technology, as one of the more mature physical improvement methods, has been widely used in the improvement of saline-alkali land. Underground drainage technology usually involves laying drainage pipes with permeable holes at a certain depth in the soil. Under the action of gravity, the high-salt water in the soil is drained out, thereby reducing the soil salinity and improving the growth environment of crop roots.

[0004] Meanwhile, solar greenhouses are installed above the saline-alkali land remediation areas. These greenhouses, covered with plastic film or glass, create a relatively enclosed planting environment above the saline-alkali land, reducing surface evaporation, regulating temperature and humidity inside the greenhouses, improving the crop growth environment, and inhibiting salt migration. The solar greenhouse covering plays a positive role in inhibiting rapid evaporation of surface soil moisture and slowing the rise of salt to the surface via capillary water.

[0005] In existing underground pipe desalination technology, the saline water collected after desalination is directly discharged, without forming a resource utilization path, resulting in a large waste of usable water resources. Summary of the Invention

[0006] This invention provides a combined system for desalination and recharge of saline-alkali land under solar greenhouses to address the problem of resource utilization.

[0007] In a first aspect, the present invention provides a coordinated system for desalination and recharge of saline-alkali land under a solar greenhouse. This system includes an intelligent monitoring and control system, a desalination collection and raw water storage system, a saline water pretreatment and desalination system, and a photovoltaic power supply and recharge salt control system, wherein: The intelligent monitoring and control system is used to receive soil condition data collected by soil condition monitoring sensors and environmental condition data collected by greenhouse environment monitoring sensors, and to determine whether the soil is in a high-salt state, whether there is a need for water replenishment, and whether it may exacerbate evaporation and salt return. The salt drainage collection and raw water regulation system includes salt drainage branch pipes and water collection wells. The salt drainage branch pipes are laid below the cultivated layer of saline-alkali land and are used to collect saline water from the soil. The water collection wells are used to temporarily store the saline water collected by the salt drainage branch pipes. The intelligent monitoring and control system is also used to output start-up commands when the start-up conditions of the saline pretreatment desalination and tailwater treatment system are met; The saline water pretreatment and desalination and tailwater treatment system is used to filter and desalinate saline water when it receives the start command output by the intelligent monitoring and control system. The photovoltaic power supply and reinjection salt control system is used to supply power to the intelligent monitoring and control system, the salt discharge collection and raw water storage system, and the saline water pretreatment desalination and tailwater treatment system. The photovoltaic power supply and reinjection salt control system is also used to transport fresh water to the greenhouse irrigation system.

[0008] This invention integrates an intelligent monitoring and control system, a salt discharge collection and raw water storage system, a saline water pretreatment and desalination and tailwater treatment system, and a photovoltaic power supply and reinjection salt control system. With the intelligent monitoring and control system as the core, the salt discharge collection and raw water storage system collects saline water to provide raw water for subsequent irrigation. The saline water pretreatment and desalination and tailwater treatment system filters and desalinates the saline water using membrane technology, converting it into fresh water that meets irrigation standards. The photovoltaic power supply and reinjection salt control system supplies power to the entire system and performs fresh water reinjection, realizing the recycling of water resources. All systems work together to form a closed-loop operation system of salt discharge-desalination-reinjection.

[0009] In one optional implementation, the water collection well is equipped with a liquid level sensor to collect the liquid level in the water collection well. The photovoltaic power supply and reinjection salt control system is equipped with an output power sensor and an energy storage SOC sensor. The output power sensor is used to output the photovoltaic power generation power, and the energy storage SOC sensor is used to output the SOC value of the energy storage battery. When the water level in the water collection well is higher than the liquid level threshold, the photovoltaic power generation power meets the start-up power of the saline water pretreatment desalination and tailwater treatment system, and the energy storage battery SOC value is higher than the minimum discharge SOC threshold, it is determined that the start-up conditions of the saline water pretreatment desalination and tailwater treatment system are met.

[0010] This invention uses the water level in the collection well, the photovoltaic power generation, and the SOC value of the energy storage battery to determine whether the start-up conditions of the saline pretreatment desalination and tailwater treatment system are met. This avoids blindly starting the system when there is insufficient raw water, insufficient power supply, or too low energy storage capacity, thereby reducing the risk of failure and extending the service life of the equipment.

[0011] In one optional embodiment, the saline water pretreatment desalination and tailwater treatment system includes a raw water pump, a saline water pretreatment unit, a membrane desalination unit, and a diversion unit. When the raw water pump receives a start command, it pumps the saline water temporarily stored in the collection well to the saline water pretreatment unit. The saline water pretreatment unit is used to filter impurities, and the membrane desalination unit is used to desalinate the filtered saline water. The diversion unit separates the desalinated water and the concentrated brine. The desalinated water is stored as fresh water in a clear water tank, and the concentrated brine is transported to the concentrated brine treatment unit. The concentrated brine treatment unit includes a concentrated brine tank, an evaporation tank, and a crystallization tank.

[0012] This invention uses a raw water pump to pump the saline water temporarily stored in the collection well to the saline water pretreatment unit for filtration and membrane desalination, thereby realizing the reuse of water resources. It separates the desalinated water and concentrated brine, avoiding the saturation and pollution of soil and water bodies caused by the direct discharge of high-salinity tailwater.

[0013] In one optional embodiment, the saline water pretreatment desalination and tailwater treatment system is further provided with a chemical dosing device, which is connected to the saline water pretreatment unit and is used to add scale inhibitors, reducing agents, and pH adjusters to the saline water before pretreatment.

[0014] This invention uses a chemical dosing device to add scale inhibitors to suppress the formation of precipitates and scale, adds reducing agents to protect membrane materials from damage by oxidizing substances, and adds pH adjusters to adjust the pH value of saline water and optimize water quality.

[0015] In one optional embodiment, the saline pretreatment desalination and tailwater treatment system is further equipped with a pressure sensor. The pressure sensor is used to collect the pressure at the inlet end of the saline water entering the membrane module and the pressure at the outlet end of the saline water after it passes through the membrane module. The difference between the pressure at the inlet end of the saline water entering the membrane module and the pressure at the outlet end of the saline water after it passes through the membrane module is determined as the membrane pressure difference. When the membrane pressure difference is higher than the preset membrane pressure difference threshold, a flushing procedure is executed, and / or the operating load is reduced, and / or a shutdown maintenance prompt signal is issued.

[0016] This invention monitors membrane pressure difference to determine abnormal operating conditions such as membrane module fouling, and takes corresponding measures to extend the service life of membrane modules, improve freshwater quality, and reduce the frequency of manual equipment maintenance.

[0017] In one optional implementation, the saline pretreatment desalination and tailwater treatment system is further equipped with a conductivity sensor. The conductivity sensor is used to measure the conductivity of the desalinated water. When the conductivity of the desalinated water is higher than the upper limit of conductivity, the desalinated water is determined to be substandard.

[0018] This invention measures the conductivity of desalinated water using a conductivity sensor to determine whether the desalinated water meets irrigation requirements, thereby avoiding the use of substandard desalinated water for irrigation and preventing secondary soil salinization.

[0019] In one optional implementation, the clear water tank and the concentrated brine tank are equipped with level sensors. When the level in the clear water tank is lower than the lower limit, the irrigation program is not started. When the level in the concentrated brine tank reaches the upper limit, the operation of the membrane desalination unit is suspended.

[0020] This invention monitors the liquid levels of the clear water tank and the concentrated brine tank using a liquid level sensor. When the liquid level in the clear water tank is low, irrigation is stopped to avoid irrigation failure due to insufficient water. When the liquid level in the concentrated brine tank is high, the operation of the membrane desalination unit is suspended to prevent the overflow of high-salt concentrated water.

[0021] In one optional implementation, the photovoltaic power supply and reinjection salt control system includes photovoltaic modules, energy storage batteries, and a power supply control unit. The photovoltaic modules are used to convert solar energy into electrical energy, the energy storage batteries are used to store excess electrical energy, and the power supply control unit is used to control the priority supply of electrical energy to real-time loads.

[0022] This invention converts solar energy into electrical energy using photovoltaic modules and stores excess electrical energy in energy storage batteries, achieving energy self-sufficiency, reducing dependence on external power grid supply, prioritizing the supply of electrical energy to real-time loads, and ensuring the stable operation of core processes such as salt removal, desalination, and irrigation.

[0023] In one optional implementation, when the photovoltaic power generation meets the load demand, the photovoltaic module supplies power to the load; when the photovoltaic power generation does not meet the load demand and the energy storage SOC is higher than the replenishment threshold, the energy storage battery supplements the power supply; when the energy storage SOC is lower than the safety lower limit, or the battery temperature exceeds the temperature threshold, the operation of energy-consuming equipment is restricted.

[0024] This invention employs a tiered power supply strategy based on photovoltaic power generation, energy storage SOC, and battery temperature to achieve energy dispatching that prioritizes power supply to photovoltaic modules and supplies energy to storage batteries on demand, thereby improving energy utilization efficiency.

[0025] In one optional implementation, the photovoltaic power supply and reinjection salt control system includes an irrigation flow sensor and an irrigation pressure sensor. When the irrigation flow is lower than the flow threshold and / or the irrigation pressure fluctuates within an abnormal range, a warning signal is generated to suspend the irrigation process.

[0026] This invention monitors irrigation flow and irrigation pressure using irrigation flow sensors and irrigation pressure sensors respectively, thus avoiding ineffective irrigation when flow or pressure is abnormal. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall architecture of a salt drainage, desalination and recharge system for saline-alkali land under a solar greenhouse, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of saline-alkali land treatment according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the intelligent monitoring and control system according to an embodiment of the present invention; Figure 4 This is a process flow diagram of the salt collection and raw water regulation system according to an embodiment of the present invention; Figure 5 This is a process flow diagram of a saline water pretreatment desalination and tailwater treatment system according to an embodiment of the present invention; Figure 6 This is a process flow diagram of a photovoltaic power supply and reinjection salt control system according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0031] This invention provides an embodiment of a combined desalination and recharge system for saline-alkali land under a solar greenhouse, such as... Figure 1 As shown, the system includes an intelligent monitoring and control system, a salt discharge collection and raw water storage system, a saline water pretreatment unit and tailwater treatment system, and a photovoltaic power supply and reinjection salt control system.

[0032] like Figure 2 As shown, the system uses the greenhouse planting area as the core area. The solar greenhouse is set up above the saline-alkali land treatment area to form a relatively closed planting environment, reduce soil surface evaporation, inhibit salt migration, and provide a spatial basis for crop planting and photovoltaic modules.

[0033] The planting area is equipped with soil condition monitoring sensors and greenhouse environment monitoring sensors. The soil condition monitoring sensors collect data on soil conditions and include soil conductivity sensors, soil moisture sensors, and soil pH sensors. The soil conductivity sensor monitors soil salinity levels, the soil moisture sensor monitors soil moisture, and the soil pH sensor monitors soil acidity / alkalinity. Greenhouse environment monitoring sensors are installed inside and on the roof of the greenhouse to collect environmental data. These sensors include temperature sensors, humidity sensors, and light intensity sensors. The temperature sensor monitors the temperature inside and on the roof of the greenhouse, the humidity sensor monitors the humidity inside the greenhouse, and the light intensity sensor monitors the light intensity.

[0034] It should be noted that the various thresholds in the embodiments of the present invention include, but are not limited to, soil salinity threshold, soil moisture content threshold, liquid level threshold, water quality threshold, energy supply threshold, and operational anomaly threshold. These thresholds are all preset based on crop growth requirements, soil type, greenhouse environmental conditions, raw water quality, desalination unit design, parameters, system specifications, and operating conditions, and can be corrected based on historical operating data. Preferably, the determination of each threshold is based on calibrated and temperature-compensated sensor data, combined with continuous sampling results.

[0035] like Figure 3 As shown, soil condition data collected by soil condition monitoring sensors and environmental condition data collected by greenhouse environment monitoring sensors are transmitted to an intelligent monitoring and control system to determine whether the soil is in a high-salt state, whether there is a need for water replenishment, and whether evaporation and salt return may be exacerbated. The determination of whether the soil is in a high-salt state is based on the temperature-compensated soil electrical conductivity monitoring value. The upper limit of soil electrical conductivity is the equivalent value of the electrical conductivity of the saturation extract (ECe) calculated according to the salt tolerance of the target crop. When the measured value is higher than the corresponding upper limit threshold, the soil is determined to be in a high-salt state. Whether there is a need for water replenishment in the crop root zone is preferably determined based on soil moisture content. The lower limit of soil moisture content is preferably determined to be a management-allowed deficit of 30%. When the detected soil electrical conductivity is higher than the preset upper limit, it is determined that the salt accumulation in the soil is high, and continued salt removal treatment is required. When the detected soil moisture content is lower than the preset lower limit, it is determined that there is a need for water replenishment in the crop root zone. When higher temperatures, lower humidity, and stronger light are detected inside the greenhouse, which enhances evaporation, the monitoring frequency of soil water and salt migration processes should be increased.

[0036] The salt discharge collection and raw water regulation system includes several salt discharge branch pipes, water collection wells and water collection main pipes. The salt discharge branch pipes are laid in advance under the soil layer, and the water collection wells are set at the edge of the greenhouse and adjacent areas.

[0037] Specifically, the salt drainage branch pipe is made of corrosion-resistant PVC or PE pipe or other corrosion-resistant materials. The pipe diameter is designed according to the soil permeability coefficient. Water-permeable holes are opened in the pipe wall, and it is wrapped with salt-resistant filter cloth and protective net. The burial depth is determined according to the distribution of the salt and alkali layer, and the laying slope is 0.2%~0.6%, preferably 0.4%. The water collection well is a corrosion-resistant water collection well, and its volume is designed according to the peak drainage of the underground pipe. It has a built-in liquid level sensor to link the start and stop of the water pump.

[0038] Under greenhouse cover, surface evaporation is suppressed, and the migration of water and salt in the soil is more concentrated in the area below the topsoil. The saline water in the soil gradually converges into the salt drainage branch pipe. The salt drainage branch pipe collects the high saline water in the surrounding soil layer through the water-permeable holes on the pipe wall. With the help of the slope, the collected saline water flows into the main water collection pipe under the action of gravity, and finally flows into the collection well for temporary storage.

[0039] It should be noted that the desalination branch pipe, main collection pipe, and collection well are equipped with flow sensors, velocity sensors, pressure sensors, level sensors, and well water TDS (Total Dissolved Solids) sensors to monitor the operational status of the desalination process in real time. This monitoring determines whether the desalination from the underground pipes is smooth, whether there are blockages or reduced drainage efficiency, and whether the salinity of the raw water in the collection well is suitable for subsequent treatment. When a continuous decrease in flow rate and an abnormal increase in pressure are detected, it indicates a risk of blockage in the underground pipes, and a maintenance warning signal is issued. When the water level in the collection well continues to rise and approaches a set threshold, conditions for pumping and desalination treatment are gradually being met.

[0040] like Figure 4 As shown, when a certain volume of saline water accumulates in the collection well, it does not immediately enter the pumping treatment stage. Instead, the intelligent monitoring and control system determines whether the start-up conditions of the saline water pretreatment desalination and tailwater treatment system are met. It determines whether the liquid level in the collection well has reached the pumping threshold, whether the TDS of the raw water in the well is within the acceptable range of the desalination system, whether the current equipment status is normal, and whether the photovoltaic energy storage power supply system can provide sufficient start-up and operating power.

[0041] The collection well is equipped with a level sensor to collect the water level. If the water level is higher than the threshold, it is determined that the water volume meets the start-up conditions. Combined with data from the photovoltaic output power sensor and the energy storage SOC sensor, it is determined whether photovoltaic power generation can meet the start-up power requirements of the saline water pretreatment desalination and tailwater treatment system, and whether the energy storage battery can supplement power supply when photovoltaic power is insufficient.

[0042] The startup conditions for the saline water pretreatment desalination and tailwater treatment system are determined only when the water level in the collection well is higher than the water level threshold, the photovoltaic power generation meets the startup power of the saline water pretreatment desalination and tailwater treatment system, and the SOC value of the energy storage battery is higher than the minimum discharge SOC threshold, i.e., "water level meets the requirements, power supply meets the requirements, and equipment is normal". This avoids blindly starting the saline water pretreatment desalination and tailwater treatment system when there is insufficient raw water, insufficient power supply, or equipment abnormality, which could lead to idling or failure.

[0043] When the start-up conditions of the saline water pretreatment desalination and effluent treatment system are met, a start-up command is output. For example... Figure 5As shown, the saline water pretreatment desalination and tailwater treatment system filters and desalinates the saline water upon receiving a start-up command. Preferably, the raw water storage condition is determined based on the water level in the collection well, and the water level threshold is preset according to the minimum safe submersion depth of the raw water pump, the minimum treatment volume required for stable operation in a single cycle, and control requirements to avoid frequent start-stop cycles. Preferably, the raw water quality condition is determined based on the total dissolved solids (TDS) content and / or conductivity of the raw water in the well, with the TDS content preferably between 2000 and 6000 mg / L; when the TDS content is within this range, the raw water is deemed suitable for subsequent desalination processes. The power supply condition is preferably determined based on the system's available power supply capacity; the equipment's operational condition is preferably determined based on the status information of the raw water pump, saline water pretreatment unit, membrane desalination unit, and related sensors.

[0044] Specifically, the saline water pretreatment desalination and tailwater treatment system includes a raw water pump, a saline water pretreatment unit, a membrane desalination unit, and a diversion unit. When the start-up conditions are met, a start-up command is sent to the raw water pump, which then begins pumping the saline water temporarily stored in the collection well to the saline water pretreatment unit. During the pumping and transportation process, the raw water flow rate and the pressure in the transportation pipeline are monitored simultaneously to ensure that the pumping process is stable and to prevent pump idling, abnormal vibration, or pipeline blockage.

[0045] After entering the saline water pretreatment unit, the water passes through a filtration device to remove suspended particles, silt, and colloidal impurities, thereby reducing the pollution load on the membrane desalination unit.

[0046] After pretreatment, the saline water enters the membrane desalination unit for desalination. The membrane desalination unit can use technologies such as reverse osmosis and electrodialysis.

[0047] In some optional implementations, depending on the raw water quality, the saline water pretreatment desalination and tailwater treatment system is also equipped with a chemical dosing device. The chemical dosing device is connected to the saline water pretreatment unit and is used to add scale inhibitors, reducing agents, and pH adjusters to the saline water before pretreatment to improve water quality stability.

[0048] In some optional implementations, turbidity sensors, pH sensors, and TDS sensors are installed at the inlet and outlet of the saline water pretreatment unit to continuously collect water quality data. Based on the collected water quality data, it is determined whether the filtration effect meets the standard, whether the filtration needs to be strengthened, whether chemical adjustment is needed, and whether the desalination parameters need to be corrected. This ensures that the water entering the membrane desalination unit is in a suitable operating condition, reduces the risk of membrane fouling, and extends the service life of the membrane module.

[0049] Specifically, during the desalination process, pressure sensors are installed before and after the membrane module. These sensors collect the pressure at the inlet of the saline water entering the membrane module (pre-membrane pressure) and the pressure at the outlet of the saline water after it has passed through the membrane module (post-membrane pressure). The difference between the pressure at the inlet and outlet of the saline water is defined as the membrane differential pressure. When the membrane differential pressure exceeds a preset threshold, it is determined that the membrane module has a fouling or scaling tendency. At this point, a flushing procedure is executed, and / or the operating load is reduced, and / or a shutdown maintenance warning signal is issued. The membrane differential pressure flushing trigger threshold is preferably determined using a relative change. When the standardized membrane differential pressure increases by 15% from the initial stable operating value, at least one of the following measures is executed: a flushing procedure, reduction of the operating load, issuance of a maintenance warning signal, or shutdown protection. Preferably, the pressure drop of a single unit is no higher than 15 psi (approximately 0.103 MPa); the pressure drop of a multi-element pressure vessel is no higher than 50 psi (approximately 0.345 MPa) to reduce the risk of membrane damage.

[0050] Specifically, during the saline water desalination process, the electrical conductivity of the desalinated water is used to determine whether the pretreatment and effluent treatment system is operating normally. Conductivity sensors are installed to measure the electrical conductivity of the desalinated water. When the electrical conductivity exceeds the upper limit, i.e., exceeds the irrigation water quality standard, the desalinated water is deemed substandard and cannot be used directly for irrigation. Instead, it requires further treatment, recirculation, or isolation. Specifically, conductivity sensors are used to monitor the desalinated water quality online, preferably using the conductivity value converted from temperature as the criterion. The upper limit of the electrical conductivity of water (ECw) is determined by inversely calculating the crop salinity threshold. Under leaching fraction conditions of 15%–20%, ECw ≤ ECe / 1.5 is preferred. When the electrical conductivity of the desalinated water exceeds the corresponding upper limit threshold, the desalinated water is deemed substandard and cannot be directly used in the irrigation reuse process. Instead, it requires further treatment, recirculation, or isolation storage.

[0051] This method allows for continuous monitoring and dynamic adjustment of the membrane desalination process, improving the stability of desalinated water and extending the service life of membrane modules.

[0052] After the membrane desalination is completed, the diversion unit separates the treated water into two streams: desalinated water and concentrated brine. The desalinated water is stored in the clear water tank as fresh water, while the concentrated brine is transported to the concentrated brine treatment unit through a dedicated management system. The concentrated brine treatment unit includes a concentrated brine tank, an evaporation tank, and a crystallization tank.

[0053] Specifically, the clear water tank is equipped with a level sensor to monitor the freshwater level in real time. The level in the clear water tank determines whether the required water volume for irrigation and reuse is available. When the level in the clear water tank is below the lower limit, the minimum requirements for irrigation are not met, and the irrigation process is temporarily suspended. During the desalination process, concentrated brine continuously flows into the concentrated brine tank, evaporation tank, and crystallization tank. To prevent environmental risks caused by wastewater overflow, the concentrated brine tank is also equipped with a level sensor to monitor the accumulated amount of concentrated brine in real time. When the level in the concentrated brine tank reaches or approaches the upper limit, the operation of the membrane desalination unit is immediately restricted or suspended, and a warning signal is issued, prompting evaporation, crystallization, off-site transportation, or other standardized treatments to prevent high-salinity wastewater overflow and effectively avoid secondary salinization or pollution caused by untimely treatment of high-salinity wastewater. When the level in the concentrated brine tank has not reached the upper limit, the normal treatment process continues.

[0054] This method achieves the separation of desalination products, providing qualified water sources for irrigation reuse while avoiding the direct discharge of high-salinity concentrated water that could cause environmental pollution.

[0055] like Figure 6 As shown, the photovoltaic power supply and reinjection salt control system provides the electrical energy required for salt discharge, water pumping, pretreatment, desalination and irrigation processes, and supplies power to the intelligent monitoring and control system, the salt discharge collection and raw water storage system, and the saline water pretreatment desalination and tailwater treatment system. The photovoltaic power supply and reinjection salt control system is also used to transport fresh water to the greenhouse irrigation system to realize reinjection and rationally utilize resources.

[0056] Specifically, the photovoltaic power supply and reinjection salt control system includes photovoltaic modules, which are installed on the top or around the greenhouse and are used to convert solar energy into electrical energy.

[0057] The photovoltaic power supply and reinjection salt control system also includes energy storage batteries. When the real-time power generation is higher than the current load demand, the energy storage batteries store excess energy.

[0058] The photovoltaic power supply and reinjection salinity control system also includes a power supply control unit. After the photovoltaic modules convert solar energy into electrical energy, the power supply control unit regulates and prioritizes supplying real-time loads such as raw water pumps, saline water pretreatment units, and membrane desalination units.

[0059] Specifically, determining whether the start-up conditions of the saline pretreatment desalination and tailwater treatment system are met requires a comprehensive assessment of the water level in the collection well, the photovoltaic power generation capacity, and the SOC value of the energy storage battery.

[0060] Specifically, energy status is continuously monitored using photovoltaic output power sensors, voltage sensors, current sensors, energy storage SOC sensors, battery temperature sensors, and load power sensors to perform energy dispatch. The dispatch strategy is as follows: When photovoltaic (PV) power generation meets load demand, PV modules are prioritized for power supply. When PV power generation does not meet load demand, and the energy storage SOC (State of Charge) is higher than the replenishment threshold, the energy storage battery provides supplementary power. When the energy storage SOC is lower than the safety lower limit, or the battery temperature exceeds the temperature threshold, the operation of high-energy-consuming equipment is restricted or a protective shutdown is implemented. This ensures the system's continuous operation capability even in remote areas or environments without a stable external power grid. The energy storage battery SOC protection lower limit is preferably 10%–20%, more preferably 20%; when the SOC is lower than the protection lower limit, the operation of high-energy-consuming equipment is restricted or a protective shutdown is implemented. To avoid frequent start-up and shutdown of the energy storage system near boundary conditions, a SOC hysteresis range consisting of a start-up allowable threshold and a protection threshold is preferably set; preferably, the start-up allowable threshold can be 10 percentage points higher than the protection threshold, for example, when the protection threshold is 20%, the start-up allowable threshold can be 30%.

[0061] Once a certain amount of desalinated water has accumulated in the clear water tank, data from the soil conductivity sensor, soil moisture sensor, and clear water tank level sensor are retrieved again to determine whether the conditions for irrigation reuse are met.

[0062] The conditions for starting irrigation include: soil electrical conductivity is higher than the upper limit of the salt control target, soil moisture content is lower than the water demand threshold, the clear water tank level is higher than the minimum irrigation level, and the irrigation network is in an operational state.

[0063] If the irrigation start-up conditions are met, an activation command is sent to the solenoid valve and drip irrigation branch, and fresh water is delivered to the crop root zone through the irrigation main pipe to achieve precise re-irrigation. If the soil moisture content is high, or the water in the clear water tank is insufficient, water is maintained and the system continues to wait.

[0064] This method allows for the assessment of soil condition and water availability before irrigation, effectively avoiding ineffective and excessive irrigation and better maintaining soil water and salt balance.

[0065] After irrigation is started, the operating status of the irrigation network is continuously monitored by irrigation flow and pressure sensors to determine if there are any branch blockages, local leaks, insufficient pressure, or valve malfunctions. When the irrigation flow rate is lower than the flow threshold and / or the irrigation pressure fluctuates abnormally, a warning signal is generated, and the irrigation program is suspended.

[0066] During and after irrigation, soil conductivity and moisture content sensors in the re-irrigated area are continuously monitored to assess the effectiveness of this round of re-irrigation in improving soil water and salt conditions. If soil conductivity decreases significantly and soil moisture content reaches the target range after re-irrigation, the salt control effect of this round of irrigation is deemed effective. Understandably, the irrigation results can be used to optimize the irrigation amount, duration, and frequency for the next round, achieving a shift from single-cycle irrigation control to continuous adaptive adjustment.

[0067] After completing one round of desalination, pumping, desalination, water storage, irrigation, and concentrated brine treatment, the intelligent monitoring and control system summarizes and analyzes the data from this round. The analyzed data includes soil salinity trends, soil moisture content changes, underground drainage flow rate changes, well water level changes, raw water salinity changes, membrane unit pressure differential changes, desalinated water quality, photovoltaic power supply status, energy storage consumption, and irrigation feedback effects. Based on the summarized analysis results, the operating strategy for the next round is optimized, such as adjusting the pumping start threshold, modifying the pretreatment intensity, changing the desalination unit load, optimizing irrigation timing and frequency, and increasing or decreasing the proportion of energy storage participation. This forms a closed-loop control chain of "collection—judgment—execution—feedback—optimization," which not only completes the water and salinity treatment tasks of the current round but also achieves continuous adaptive optimization during long-term operation.

[0068] After this round of operation concludes, the process returns to the soil and environmental condition monitoring phase, restarting with a new round of soil condition identification, salt collection, desalination treatment, and irrigation reuse. With each cycle, the control strategy is continuously updated based on sensor feedback, gradually reducing soil salinity within the greenhouse coverage area, making irrigation water supply more precise, energy utilization more rational, and concentrated brine disposal safer. This forms a continuously closed-loop, adaptive, and optimized collaborative governance system. Through the integration of multiple systems and unified scheduling, the comprehensive goals of saline-alkali land management, saline water resource utilization, and energy-saving operation can be achieved in solar greenhouse scenarios.

[0069] The salinity removal, desalination, and recharge system provided in this embodiment for saline-alkali land under solar greenhouses integrates an intelligent monitoring and control system, a salinity removal and raw water storage system, a saline water pretreatment and desalination and tailwater treatment system, and a photovoltaic power supply and recharge salinity control system. With the intelligent monitoring and control system as the core, the salinity removal and raw water storage system collects saline water to provide raw water for subsequent irrigation. The saline water pretreatment and desalination and tailwater treatment system filters and desalinates the saline water using membrane technology, converting it into fresh water that meets irrigation standards. The photovoltaic power supply and recharge salinity control system supplies power to the entire system and performs fresh water recharge, realizing the recycling of water resources. All systems work together to form a closed-loop operation system of salinity removal, desalination, and recharge.

[0070] In terms of the effectiveness of saline-alkali land management, relying on the coverage of solar greenhouses can effectively reduce the intensity of surface evaporation and inhibit the migration of salt to the surface through capillary action. At the same time, by combining underground pipe drainage with drip irrigation reuse, the migration path of salt is shortened and the efficiency of downward migration and discharge of salt is enhanced, thereby improving the effect of saline-alkali land improvement, making the soil water and salt environment more stable, and conducive to crop growth.

[0071] In terms of energy utilization, by integrating photovoltaic power generation systems on or around the greenhouse, local power supply can be provided for desalination equipment, water pumps, and control systems, forming an energy self-sufficiency system. By introducing energy storage units and combining them with intelligent dispatch strategies, the system can be guaranteed to operate continuously when sunlight is insufficient, effectively reducing dependence on the external power grid and significantly reducing operating costs, making it particularly suitable for remote areas or areas without power grid coverage.

[0072] In terms of water treatment, a pretreatment module is set up before the saline water enters the membrane desalination unit. Through filtration and chemical adjustment, the turbidity of the influent and the risk of scaling are reduced. Combined with real-time monitoring of parameters such as membrane pressure difference and influent and effluent water quality, dynamic control of membrane fouling and operating status is achieved, thereby extending the service life of the membrane module and improving the system's operational stability and the quality of freshwater output.

[0073] In terms of intelligent control, multiple types of sensors are deployed to collect real-time data on soil water and salt status, desalination process, water quality parameters, equipment operating status, and energy status. The intelligent monitoring and control system then processes this data, identifies the status, and makes decisions, enabling coordinated scheduling of pumping, pretreatment, desalination, energy supply, and irrigation processes. This multi-source data-driven control method allows the system to automatically adjust its operating strategies according to environmental changes, improving system efficiency and adaptability.

[0074] In terms of environmental protection, by centrally collecting concentrated brine and transporting it to evaporation ponds or crystallization facilities for standardized treatment, the direct discharge of high-salinity wastewater can be avoided from polluting the surrounding soil and water bodies. At the same time, it provides conditions for the subsequent utilization of salt resources, which has good ecological benefits.

[0075] In terms of system scalability, the modular greenhouse unit design allows for replication and expansion based on the scale of the treatment area, making it suitable for the zoned treatment of large areas of saline-alkali land. The subsystems are connected through standard interfaces, facilitating project implementation and maintenance, and demonstrating good engineering applicability and promotional value.

[0076] In summary, by organically combining structural integration, energy optimization, and intelligent control, the technical bottlenecks of low salt removal efficiency, low saline water utilization rate, and high energy consumption in traditional saline-alkali land management have been overcome. This has achieved synergistic optimization of saline-alkali land improvement, water resource recycling, and clean energy application, resulting in significant economic, ecological, and social benefits.

[0077] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended invention.

Claims

1. A combined system for desalination, salt removal, and recharge in saline-alkali land under a solar greenhouse, characterized in that, The system includes an intelligent monitoring and control system, a salt discharge collection and raw water storage system, a saline water pretreatment and desalination and tailwater treatment system, and a photovoltaic power supply and reinjection salt control system, wherein: The intelligent monitoring and control system is used to receive soil status data collected by soil status monitoring sensors and environmental status data collected by greenhouse environment monitoring sensors, and to determine whether the soil is in a high-salt state, whether there is a need for water replenishment, and whether it may exacerbate evaporation and salt return. The salt drainage collection and raw water regulation system includes a salt drainage branch pipe and a water collection well. The salt drainage branch pipe is laid below the cultivated layer of saline-alkali land covered by the solar greenhouse. The salt drainage branch pipe is used to collect saline water in the soil. The water collection well is used to temporarily store the saline water collected by the salt drainage branch pipe. The intelligent monitoring and control system is also used to output a start command when the start-up conditions of the saline pretreatment desalination and tailwater treatment system are met. The saline water pretreatment desalination and tailwater treatment system is used to filter and desalinate saline water using membrane technology when it receives a start command from the intelligent monitoring and control system. The photovoltaic power supply and reinjection salt control system is used to supply power to the intelligent monitoring and control system, the salt discharge collection and raw water storage system, and the saline water pretreatment desalination and tailwater treatment system. The photovoltaic power supply and reinjection salt control system is also used to transport fresh water to the greenhouse irrigation system.

2. The system according to claim 1, characterized in that, The water collection well is equipped with a liquid level sensor to collect the liquid level in the water collection well. The photovoltaic power supply and reinjection salt control system is equipped with an output power sensor and an energy storage SOC sensor. The output power sensor is used to output the photovoltaic power generation power, and the energy storage SOC sensor is used to output the SOC value of the energy storage battery. When the water level in the water collection well is higher than the liquid level threshold, the photovoltaic power generation power meets the start-up power of the saline water pretreatment desalination and tailwater treatment system, and the energy storage battery SOC value is higher than the minimum discharge SOC threshold, the start-up conditions of the saline water pretreatment desalination and tailwater treatment system are determined to be met.

3. The system according to claim 1, characterized in that, The saline water pretreatment desalination and tailwater treatment system includes a raw water pump, a saline water pretreatment unit, a membrane desalination unit, and a diversion unit. When the raw water pump receives a start command, it pumps the saline water temporarily stored in the collection well to the saline water pretreatment unit. The saline water pretreatment unit is used to filter impurities. The membrane desalination unit is used to desalinate the filtered saline water. The diversion unit separates the desalinated water and the concentrated brine. The desalinated water is stored as fresh water in a clear water tank, and the concentrated brine is transported to the concentrated brine treatment unit. The concentrated brine treatment unit includes a concentrated brine tank, an evaporation tank, and a crystallization tank.

4. The system according to claim 3, characterized in that, The saline water pretreatment desalination and tailwater treatment system is also equipped with a chemical dosing device, which is connected to the saline water pretreatment unit. The chemical dosing device is used to add scale inhibitors, reducing agents, and pH adjusters to the saline water before pretreatment.

5. The system according to claim 1, characterized in that, The saline pretreatment desalination and tailwater treatment system is also equipped with a pressure sensor. The pressure sensor is used to collect the pressure at the inlet end of the saline water entering the membrane module and the pressure at the outlet end of the saline water after it passes through the membrane module. The difference between the pressure at the inlet end of the saline water entering the membrane module and the pressure at the outlet end of the saline water after it passes through the membrane module is determined as the membrane pressure difference. When the membrane pressure difference is higher than the preset membrane pressure difference threshold, a flushing procedure is executed, and / or the operating load is reduced, and / or a shutdown maintenance prompt signal is issued.

6. The system according to claim 1, characterized in that, The saline water pretreatment desalination and tailwater treatment system is also equipped with a conductivity sensor, which is used to measure the conductivity of the desalinated water. When the conductivity of the desalinated water is higher than the upper limit of conductivity, the desalinated water is determined to be substandard.

7. The system according to claim 3, characterized in that, The clear water tank and the concentrated brine tank are equipped with level sensors. When the level in the clear water tank is lower than the lower limit, the irrigation program will not be started. When the level in the concentrated brine tank reaches the upper limit, the operation of the membrane desalination unit will be suspended.

8. The system according to claim 1, characterized in that, The photovoltaic power supply and reinjection salt control system includes photovoltaic modules, energy storage batteries, and a power supply control unit. The photovoltaic modules are used to convert solar energy into electrical energy, the energy storage batteries are used to store excess electrical energy, and the power supply control unit is used to control the priority supply of electrical energy to real-time loads.

9. The system according to claim 8, characterized in that, When the photovoltaic power generation meets the load demand, the photovoltaic module supplies power to the load; when the photovoltaic power generation does not meet the load demand and the energy storage SOC is higher than the replenishment threshold, the energy storage battery provides supplementary power; when the energy storage SOC is lower than the safety lower limit, or the battery temperature exceeds the temperature threshold, the operation of energy-consuming equipment is restricted.

10. The system according to claim 1, characterized in that, The photovoltaic power supply and recharge salt control system includes an irrigation flow sensor and an irrigation pressure sensor. When the irrigation flow is lower than the flow threshold and / or the irrigation pressure fluctuates within an abnormal range, a prompt signal is generated to suspend the irrigation process.

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