Solar-wind energy can be used to create a closed-loop freshwater system for salt fields and improve algae cultivation in saline-alkali land.

Abstract

This invention discloses a closed-loop system for freshwater production from salt fields using wind and solar power, and for algae cultivation in saline-alkali land improvement. It comprises six main units: wind and solar power supply, sealed salt production, in-situ saline-alkali land improvement and cultivation, salt-tolerant algae cultivation, a two-way multi-functional pipeline network, and intelligent sensing and control. The system achieves efficient freshwater recovery through sealed salt production coupled with condensation; long-term improvement through permanent HDPE waterproofing and in-situ straw mixing; tiered resource utilization through multi-shed linkage and gradient cultivation; and zero-carbon operation through wind and solar power. This forms a closed loop of "salt washing—salt production—freshwater production—cultivation—reuse," with zero wastewater and zero waste salt discharge, simultaneously producing refined salt, freshwater, crops, and algae powder. This invention is suitable for severely saline-alkali and arid areas, solving the problems of water shortage, salinization, high energy consumption, and large emissions, achieving synergy between ecological improvement and high-value production.

Description

Technical Field

[0001] This invention belongs to the fields of saline-alkali land ecological improvement, water-saving agriculture in arid areas, wind and solar renewable energy utilization, comprehensive utilization of seawater / saline-alkali water and microalgae cultivation coupling technology. Specifically, it relates to an integrated closed-loop device and operation method for wind and solar energy driven, sealed salt production, in-situ saline-alkali land improvement, facility planting and salt-tolerant algae cultivation suitable for severely saline-alkali and arid areas. Background Technology

[0002] my country faces large areas of severely saline-alkali land and drought-stricken water shortages. Traditional saline-alkali land improvement methods suffer from drawbacks such as high freshwater consumption, environmental pollution from leachate discharge, recurring secondary salinization, high energy dependence, and low resource utilization. Conventional salt production through solar evaporation is inefficient and freshwater recovery is difficult. The disposal of concentrated brine, a byproduct of seawater desalination, is a significant challenge. Monoculture or aquaculture alone cannot achieve tiered resource utilization and zero emissions. Current technologies lack an integrated system that combines wind and solar power generation, sealed evaporation for salt production, condensation and freshwater recovery, in-situ soil improvement, facility-based planting, and salt-tolerant algae cultivation, enabling multi-energy coupling, material closed-loop management, and intelligent control. This makes it difficult to meet the demands of large-scale, green, and high-value agricultural production in arid and saline-alkali areas. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a closed-loop salt field system for freshwater production and algae cultivation in saline-alkali land. It utilizes wind and solar power as the core energy source, sealed salt evaporation-condensation for freshwater production as the core water cycle, in-situ straw mixing and permanent seepage prevention as the core soil improvement, and multi-shed linkage (planting shed, algae cultivation shed, and sealed salt evaporation shed) as the core production method. This system achieves a closed-loop cycle of freshwater, salt, heat, and nutrients, resulting in zero wastewater and zero waste salt discharge. Simultaneously, it produces refined salt, freshwater, crops, and algae powder, overcoming the industrial bottlenecks of water scarcity, soil shortage, power shortage, and ecological fragility in arid and saline-alkali areas.

[0004] The technical solution of this invention is as follows.

[0005] A closed-loop system for producing freshwater from saline-alkali land using wind and solar energy, and for cultivating algae, includes a wind-solar hybrid energy supply unit, a sealed salt-producing unit, an in-situ saline-alkali land improvement and cultivation unit, a salt-tolerant algae cultivation unit, a two-way multi-functional pipeline network unit, and an intelligent sensing and control unit; all units are closed and interconnected, with energy utilized in a cascade manner and materials circulated in a closed loop.

[0006] The wind-solar hybrid power supply unit includes solar photovoltaic panels, wind turbines, and supporting energy storage battery modules installed on the roof / open ground, providing 24-hour uninterrupted clean power for the entire system's pumps, fans, lighting, sensing, and control equipment.

[0007] The sealed salt-producing unit includes a sealed greenhouse or a membrane-covered salt field, a shell-and-tube condenser assembly, a primary distillation medium-temperature freshwater storage tank, a secondary distillation freshwater storage tank, and a low-temperature freshwater storage tank. The raw brine is preheated by the condenser and then sprayed into the sealed salt field. Strong light and a closed system evaporate the brine, creating high-temperature, high-humidity air, which is then pumped to the shell-and-tube condenser for condensation to produce medium-temperature freshwater. The condenser uses low-temperature freshwater or the raw brine as a cooling medium. After heat exchange and temperature increase, the condenser is reused for spraying in the planting shed or as feed into the salt field. The dry medium-temperature / dry cold air discharged from the condenser is returned to the sealed salt field, planting shed, or livestock shed as needed for temperature regulation.

[0008] The in-situ saline-alkali land improvement planting unit includes a fully enclosed planting shed, a permanent impermeable saline-alkali membrane at the base, a mixed straw-improved saline-alkali soil layer, a two-way multi-functional pipeline matrix, a high-pressure fine mist spraying device, intelligent supplemental lighting, and air / soil temperature and humidity sensors. A 60cm deep pit is excavated in the planting area, and the base and sidewalls are fully covered with a 1.5mm thick high-density polyethylene impermeable membrane to prevent saline-alkali backflow. Native saline-alkali soil is mixed with 2-5mm well-rotted corn straw particles at a volume ratio of 7:3 and backfilled to form an improved soil layer. The two-way multi-functional pipeline matrix is ​​buried at the bottom of the improved soil layer, enabling rapid switching between multiple functions such as water suction, salt washing and drainage, water, fertilizer and pesticide spraying, deep-layer ventilation and oxygenation, and hot and cold air delivery. Humid and hot air from the planting shed is extracted to a condenser for desalination, creating a constant temperature and humidity precise planting environment.

[0009] The salt-tolerant algae cultivation unit includes a photovoltaic panel-shaded algae cultivation shed, an algae cultivation pond, a two-way pipe matrix with filter cloth at the bottom of the pond, water temperature and salinity sensors, supplemental lighting, and a circulating spray pump. The cultivation water uses raw material saline-alkali water or concentrated brine of appropriate concentration. The bottom pipe network realizes water circulation spraying, wastewater filtration and discharge, and reverse ventilation for oxygenation. Humid air from the cultivation shed is drawn into the condenser for desalination, and dry and cold air is blown in to regulate the temperature. The cultivation wastewater is collected into the raw material saline-alkali water system, preheated, and then sent to a sealed salt field for concentration and crystallization.

[0010] The bidirectional multifunctional pipeline unit includes a bidirectional multifunctional pipeline matrix in the planting area, a pipeline matrix with filter cloth at the bottom of the aquaculture pond, a cross-unit connecting main pipe, a pump and valve group, and a sealed quick interface, realizing integrated switching of fresh water transportation, saline water transportation, hot and cold air transportation, spraying, suction, drainage, ventilation, and water, fertilizer and medicine injection.

[0011] The intelligent sensing and control unit includes a sunlight intensity sensor, an air temperature and humidity sensor, a planting soil temperature and humidity sensor, and a water temperature and salinity sensor. It controls supplementary lighting, spraying, ventilation, air supply, and pump valve switching in a coordinated manner to dynamically maintain optimal growth and evaporation conditions for the air, soil, and water in the greenhouse.

[0012] The closed-loop operation mode is as follows: freshwater rinsing of soil in planting sheds—collection of brine and delivery to sealed salt fields—evaporation and crystallization to produce salt—condensation of hot and humid air to produce freshwater—freshwater return to planting and aquaculture; algae cultivation in concentrated brine in aquaculture sheds—concentration of wastewater and delivery to salt fields—evaporation and crystallization and freshwater recovery; power supply by wind and solar energy—cascade heat exchange in condensers—multi-shed temperature control linkage; no wastewater discharge or waste salt accumulation throughout the entire process, and a freshwater recycling rate of ≥95%.

[0013] The in-situ improved soil layer is a mixture of native saline-alkali soil and decomposed straw particles in a volume ratio of 7:3, which is then compacted in layers to form a loose, breathable, high-organic-matter, and highly buffered planting layer, eliminating the need for external soil.

[0014] The seepage-proof and salt-alkali-proof membrane is a 1.5mm thick high-density polyethylene membrane, with full coverage of the base and sidewalls without any seams, permanently blocking the capillary rise of underground saline water and preventing secondary salinization from the source.

[0015] The algae cultivation adopts a gradient salinity adaptation: Chlorella is cultivated in slightly saline water, Dunaliella salina is cultivated in moderately saline water, and Dunaliella salina is cultivated in heavily saline water / concentrated seawater desalination water.

[0016] The planting adopts a gradient of salt-tolerant crops: lettuce and romaine lettuce are planted in slightly saline-alkali land; bok choy is planted in moderately saline-alkali land; and highly salt-tolerant arugula and grain crops are planted in severely saline-alkali land.

[0017] The above solutions can be summarized as follows: A closed-loop device for improving saline-alkali land and cultivating algae using wind and solar energy in a sealed salt field is characterized by comprising a wind-solar complementary energy supply unit, a sealed salt-drying and desalination unit, an in-situ saline-alkali land improvement and cultivation unit, a salt-tolerant algae cultivation unit, a two-way multi-functional pipeline network unit, and an intelligent sensing and control unit; each unit is sealed and interconnected, with energy utilized in a cascade manner and materials circulated in a closed loop. The wind-solar hybrid power supply unit includes solar photovoltaic panels, wind turbines, and energy storage battery modules; The sealed salt drying and desalination unit includes a sealed salt drying field greenhouse / frame film, a condenser group, a primary distillation medium-temperature desalination water storage tank, a secondary distillation desalination water storage tank, and a low-temperature desalination water storage tank. The raw material brine water is preheated by the condenser and then sent into the sealed salt drying field. The high-temperature and high-humidity air generated by evaporation is drawn to the condenser to condense and produce desalination water. The dry air discharged from the condenser is returned to each greenhouse as needed to regulate the temperature. The in-situ saline-alkali land improvement planting unit includes a fully enclosed planting shed, a 1.5mm thick HDPE permanent impermeable saline-alkali membrane, an improved soil layer made by mixing native saline-alkali soil and decomposed straw in a volume ratio of approximately 7:3, a two-way multi-functional pipeline matrix in the soil layer of the planting area, a spray device in the shed, supplemental lighting, and air / soil temperature and humidity sensors. The salt-tolerant algae cultivation unit includes a cultivation shed under photovoltaic panels, a cultivation pond, a two-way pipe matrix with filter cloth at the bottom of the pond, a water temperature and salinity sensor, supplemental lighting, and a circulating spray pump; the cultivation wastewater is fed into the raw material saline-alkali water system, and after preheating, it is sent to a sealed salt field. The intelligent sensing and control unit includes a sunlight intensity sensor, an air temperature and humidity sensor, a soil temperature and humidity sensor, and a water temperature and salinity sensor, which are linked to control supplementary lighting, spraying, ventilation, and pump valve switching.

[0018] The planting area is excavated to a depth of 60cm, and the base and sidewalls are fully covered by a seepage-proof and salt-alkali-proof membrane with no seams, permanently blocking the capillary rise of underground saline-alkali water.

[0019] The improved soil layer is formed by uniformly mixing native saline-alkali soil with 2–5 mm decomposed corn stalk particles in a volume ratio of approximately 7:3, and then compacting the mixture in layers.

[0020] The bidirectional multi-functional pipeline matrix in the planting area is buried at the bottom of the improved soil layer with a spacing of 50cm, integrating functions such as water pumping, salt washing and drainage, water, fertilizer and pesticide spraying, deep air supply and oxygenation, and hot and cold air transportation.

[0021] The pipeline matrix at the bottom of the aquaculture pond is fitted with a filter cloth to realize water circulation spraying, wastewater filtration and discharge, reverse ventilation and oxygenation, and water, fertilizer and medicine delivery.

[0022] The closed-loop operation is as follows: freshwater rinsing of the planting soil → brine sent to the sealed salt field → evaporation and crystallization to produce salt → condensation of hot and humid air to produce freshwater → freshwater returned to planting and aquaculture; concentrated aquaculture water for algae cultivation → wastewater concentration and fed into the salt field; wind and solar power supply → cascade heat exchange in the condenser → multi-shed temperature regulation linkage, with zero wastewater and zero waste salt discharge throughout the entire process.

[0023] Cultivation and aquaculture gradient adaptation: Lettuce / romaine lettuce are planted and Chlorella is cultivated in slightly saline-alkali land; Chinese cabbage is planted and Dunaliella salina is cultivated in moderately saline-alkali land; Dunaliella salina is cultivated in highly saline-alkali land / concentrated brine from desalination and highly salt-tolerant Arugula is planted.

[0024] The condenser uses low-temperature fresh water or raw material brine as the cooling medium. After heat exchange and heating, it is reused for spraying in planting sheds or feeding into salt fields.

[0025] The hot and humid air from planting sheds, breeding sheds, and salt fields is all drawn into a condenser for condensation and desalination, realizing the centralized recovery of fresh water from multiple sources of hot and humid air.

[0026] By continuously supplying air and oxygen to the improved soil layer through the reverse inlet of the pipeline network, soil compaction is broken up and microbial activity is enhanced.

[0027] The beneficial effects of this invention are: 1) Driven by clean wind and solar energy, it operates with zero carbon emissions and is suitable for desert areas without power grids; 2) Sealed salt drying coupled with condensation for desalination results in high freshwater recovery rate, a closed loop of salt washing, salt production, and desalination, with zero wastewater and zero waste salt; 3) In-situ straw mixing and improvement + permanent seepage prevention eliminates the need for soil replacement, reduces costs, and provides long-term protection against salt return; 4) tiered utilization of saline-alkali water for planting and algae cultivation yields high-value crops and algae powder; 5) Multi-shed linkage and intelligent control ensure constant temperature and humidity for high yields, suitable for extremely arid and saline-alkali environments; 6) It can absorb concentrated brine from seawater desalination, solving the problem of concentrated brine discharge in coastal and Middle Eastern regions. Attached Figure Description

[0028] Figure 1. Schematic diagram of the overall structure of the system of the present invention.

[0029] Figure 2. Schematic diagram of the multi-unit linkage process of the present invention.

[0030] Figure 1-2 The numbers for each part are as follows: 1-Solar photovoltaic panels and wind turbines; 2-Sealed salt field greenhouse / frame membrane; 3-Diluted medium-temperature freshwater storage tank; 4-Planting shed; 5-Low-temperature freshwater cooling pipe shell condenser; 6-Planting shed supplemental lighting; 7-Raw material brine cooling pipe shell condenser; 8-Permanent impermeable brine membrane; 9-Salt field crystallization zone; 10-Straw-mixed improved saline-alkali soil layer; 11-Two-way multi-functional pipeline matrix in planting area; 12-Raw material brine; 13-Salt washing drainage from planting soil layer to salt field; 14-Condenser preheating of brine into salt field; 15-High-temperature and high-humidity air from salt field to condenser; 16-Dry medium-temperature air returned to salt field / planting shed; 17-Medium-temperature freshwater transported to planting shed; 18-Humid air from planting shed to condenser; 19-Dry and cold air returned to planting shed / planting shed 20-Double-distilled freshwater enters the double-distilled water storage tank; 21-Sunlight intensity sensor; 22-Air temperature and humidity sensor; 23-Planting soil temperature and humidity sensor; 24-Double-distilled freshwater storage tank; 25-Soil layer pipeline reverse inlet; 26-Air-cooled cooler hot air enters the evaporation crystallization shed; 27-Air-cooled cooler; 28-Low-temperature freshwater storage tank; 29-Low-temperature freshwater enters the condenser; 30-Heated freshwater spray enters the planting shed; 31-Algae cultivation shed under photovoltaic power; 32-Algae cultivation pond; 33-Suitable algae saline-alkali water; 34-Cultivation pond bottom with filter cloth pipeline matrix; 35-Cultivation wastewater returned to raw material saline-alkali water; 36-Humid air from the cultivation shed to the condenser; 37-Dry and cold air enters the cultivation shed; 38-Cultivation shed supplemental lighting; 39-Water temperature and salinity sensor; 40-Cultivation water circulation spray pump; 41-Cultivation pond pipeline reverse ventilation port. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Example

[0032] like Figure 1-2 As shown, a closed-loop device for improving saline-alkali land and cultivating algae using wind and solar energy to seal salt fields and produce freshwater is available, suitable for large-scale agriculture in severely saline-alkali and arid areas.

[0033] 1) Base seepage prevention laying: dig a pit 60cm deep in the planting area, and lay a 1.5mm thick HDPE seepage prevention and salt-alkali barrier membrane (8) on the base and side walls without splicing to block the seepage of underground salt-alkali water.

[0034] 2) Pipeline matrix layout: A two-way multi-functional pipeline matrix (11) is laid on the impermeable membrane inside the planting shed. The spacing between the deep pipelines is 50cm. It is used for water pumping, water and fertilizer spraying, hot and cold air transportation, deep oxygenation, salt collection and drainage. The interface is sealed to prevent blockage. A pipeline matrix (34) with filter cloth is laid at the bottom of the water pool (32) in the breeding shed. It is used for water circulation spraying, wastewater discharge, reverse ventilation, and water and fertilizer transportation.

[0035] 3) In-situ soil improvement: The native saline-alkali soil and 2-5mm decomposed corn stalk particles are mixed evenly at a volume ratio of 7:3, backfilled and compacted in layers to form a loose, breathable, and high organic matter improved planting soil layer (10), without the need for external soil.

[0036] 4) Main structure construction: The salt field is covered by a sealed greenhouse / frame film (2), and a fully enclosed planting shed (4) and a photovoltaic algae cultivation shed (31) are built adjacent to it. The base of each shed is waterproofed. After the raw material saline water is adjusted, it enters the cultivation shed (33) and is sprayed into the pool (32). The pump is used for circulating spraying (40), and dry and cold air (19) is blown in (37). The humid air on the top of the shed is drawn into the condenser (15) to produce desalinated water. The cultivation wastewater (35) is collected into the raw material saline water (12), preheated by the condenser (14) and sprayed into the sealed salt field (2). The salt is purified and removed in the crystallization zone (9). High-temperature and high-humidity air (15) is condensed by condenser (7) to produce medium-temperature fresh water (17), which is then fed into the primary fresh water tank (3) or directly supplied to the planting shed; the condensed dry medium-temperature air (16) is sent back to the salt field or planting shed for temperature regulation; the humid and hot air (18) in the planting shed is drawn into condenser (7) to produce fresh water (20) which is then fed into the secondary fresh water tank (24); the low-temperature primary fresh water (29) is used as a cooling medium for heat exchange and temperature rise, and then flows back to the planting shed for spraying (30); the dry and cold air (19) is blown back to the planting shed or sent to the breeding shed (37), thus realizing the linkage between irrigation and temperature regulation.

[0037] 5) Energy supply system assembly: Photovoltaic panels, small wind turbines and energy storage modules (1) are installed outside the shed to provide wind and solar complementarity and energy storage for continuous power supply, ensuring uninterrupted power supply for 24 hours.

[0038] 6) Intelligent control installation: The planting shed is equipped with intelligent supplemental lighting (6), and the spectral brightness is adjusted according to the light intensity (21) and the growth period; an air temperature and humidity sensor (22), a soil temperature and humidity sensor (23), and a water temperature and salinity sensor (39) are configured to link constant temperature and humidity control.

[0039] 7) Coordinated regulation and adjustment: During the summer when the temperature is high and the sun is strong, start the spray (30) to cool down and shade, draw the hot and humid air (18) into the condenser, and return the dry and cold air (19) to regulate the temperature. The underground pipe network (13) quickly drains the accumulated water to achieve salt washing and drainage, prevent root rot and prevent caking.

[0040] 8) Soil oxygenation and maintenance: Through the reverse inlet (25) of the pipeline network, air is continuously supplied to the deep soil layer to increase oxygen throughout the day, break up the compaction, and enhance the activity of microorganisms.

[0041] 9) Gradual selection of planting and cultivation: According to soil salinity: lightly saline-alkaline soil, plant lettuce / romaine lettuce and cultivate Chlorella; moderately saline soil, plant Chinese cabbage and cultivate medium-salt Dunaliella salina; heavily saline soil, plant highly salt-tolerant arugula and cultivate high-salt Dunaliella salina; in the Middle East, concentrated brine from desalinated seawater can be used to cultivate Dunaliella salina.

[0042] 10) Closed-loop salt washing cycle: The soil is regularly rinsed with fresh water (17, 30), and the salt is sent to the sealed salt field (2) through the pipeline (13) with the water. The salt is separated by evaporation and crystallization, and the condensed fresh water is returned to the planting system. The whole process is a closed loop with zero emissions.

[0043] 11) Multi-shed linkage operation: the aquaculture shed uses concentrated brine to cultivate algae, and the tail brine is sent to the salt field to produce salt and fresh water; the fresh water is used for improvement and planting; the brine from planting is washed back into the salt field; multiple sheds share fresh water and hot and cold air, which greatly reduces fresh water consumption; achieve zero waste salt and zero wastewater, dispose of concentrated brine, and simultaneously produce refined salt, fresh water, algae powder and crops, turning waste into treasure.

[0044] Components and labels not mentioned are as described above.

Claims

1. A wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, characterized in that, It includes a wind-solar hybrid energy supply unit, a sealed salt-producing unit, an in-situ saline-alkali land improvement and planting unit, a salt-tolerant algae cultivation unit, a two-way multi-functional pipeline network unit, and an intelligent sensing and control unit; each unit is sealed and interconnected, with energy utilized in a cascade manner and materials recycled in a closed loop. The wind-solar hybrid power supply unit includes solar photovoltaic panels, wind turbines, and energy storage battery modules; The sealed salt drying and desalination unit includes a sealed salt drying field greenhouse / frame film, a condenser group, a primary distillation medium-temperature desalination water storage tank, a secondary distillation desalination water storage tank, and a low-temperature desalination water storage tank. The raw material brine water is preheated by the condenser and then sent into the sealed salt drying field. The high-temperature and high-humidity air generated by evaporation is drawn to the condenser to condense and produce desalination water. The dry air discharged from the condenser is returned to each greenhouse as needed to regulate the temperature. The in-situ saline-alkali land improvement planting unit includes a fully enclosed planting shed, a 1.5mm thick HDPE permanent impermeable saline-alkali membrane, an improved soil layer made by mixing native saline-alkali soil and decomposed straw in a volume ratio of approximately 7:3, a two-way multi-functional pipeline matrix in the soil layer of the planting area, a spray device in the shed, supplemental lighting, and air / soil temperature and humidity sensors. The salt-tolerant algae cultivation unit includes a cultivation shed under photovoltaic panels, a cultivation pond, a two-way pipe matrix with filter cloth at the bottom of the pond, a water temperature and salinity sensor, supplemental lighting, and a circulating spray pump; the cultivation wastewater is fed into the raw material saline-alkali water system, and after preheating, it is sent to a sealed salt field. The intelligent sensing and control unit includes a sunlight intensity sensor, an air temperature and humidity sensor, a soil temperature and humidity sensor, and a water temperature and salinity sensor, which are linked to control supplementary lighting, spraying, ventilation, and pump valve switching.

2. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The planting area is excavated to a depth of 60cm, and the base and sidewalls are fully covered by a seepage-proof and salt-alkali-proof membrane with no seams, permanently blocking the capillary rise of underground saline-alkali water.

3. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The improved soil layer is formed by uniformly mixing native saline-alkali soil with 2–5 mm decomposed corn stalk particles in a volume ratio of approximately 7:3, and then compacting the mixture in layers.

4. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The bidirectional multi-functional pipeline matrix in the planting area is buried at the bottom of the improved soil layer with a spacing of 50cm, integrating functions such as water pumping, salt washing and drainage, water, fertilizer and pesticide spraying, deep air supply and oxygenation, and hot and cold air transportation.

5. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The pipeline matrix at the bottom of the aquaculture pond is fitted with a filter cloth to realize water circulation spraying, wastewater filtration and discharge, reverse ventilation and oxygenation, and water, fertilizer and medicine delivery.

6. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The closed-loop operation is as follows: freshwater rinsing of the planting soil → brine sent to the sealed salt field → evaporation and crystallization to produce salt → condensation of hot and humid air to produce freshwater → freshwater returned to planting and aquaculture; concentrated aquaculture water for algae cultivation → wastewater concentration and fed into the salt field; wind and solar power supply → cascade heat exchange in the condenser → multi-shed temperature regulation linkage, with zero wastewater and zero waste salt discharge throughout the entire process.

7. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... Cultivation and aquaculture gradient adaptation: Lettuce / romaine lettuce are planted and Chlorella is cultivated in slightly saline-alkali land; Chinese cabbage is planted and Dunaliella salina is cultivated in moderately saline-alkali land; Dunaliella salina is cultivated in highly saline-alkali land / concentrated brine from desalination and highly salt-tolerant Arugula is planted.

8. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The condenser uses low-temperature fresh water or raw material brine as the cooling medium. After heat exchange and heating, it is reused for spraying in planting sheds or feeding into salt fields.

9. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... The hot and humid air from planting sheds, breeding sheds, and salt fields is all drawn into a condenser for condensation and desalination, realizing the centralized recovery of fresh water from multiple sources of hot and humid air.

10. The wind-solar energy-powered closed salt field freshwater production system for improving saline-alkali land and cultivating algae, as described in claim 1, is characterized in that... By continuously supplying air and oxygen to the improved soil layer through the reverse inlet of the pipeline network, soil compaction is broken up and microbial activity is enhanced.

Images