Efficient outdoor dunaliella salina culture system based on brine resources

Abstract

The invention discloses an efficient outdoor dunaliella salina culture system based on brine resources. The efficient outdoor dunaliella salina culture system comprises a brine collection and storage module, a brine pretreatment module, an inoculation and initial culture module and a large-scale outdoor culture module which are communicated in sequence, the brine pretreatment module comprises an original brine buffer pool, a purification pool and a nutritive salt blending pool which are communicated in sequence, a micro-nano bubble generator, a heating device and an electrochemical disinfection device are arranged in the original brine buffer pool, a conveying pipeline with an electromagnetic valve is communicated between the original brine buffer pool and the purification pool, a free chlorine sensor is arranged in the original brine buffer pool, and the nutritive salt blending pool is communicated with the purification pool. The free chlorine sensor is in signal connection with an electromagnetic valve on the conveying pipeline through a controller; an alkaline solution and an interception screen plate are arranged in the purification tank; and a microfiltration device is communicated between the nutritive salt blending tank and the purification tank. By means of module integration and automatic control, the brine pretreatment process is shortened, the equipment cost is reduced, and the system has the all-weather operation capacity and is suitable for large-scale outdoor dunaliella salina cultivation.

Description

Technical Field

[0001] This invention relates to the field of microalgae cultivation technology, and more specifically, to a high-efficiency outdoor Dunaliella salina cultivation system based on brine resources, particularly a large-scale outdoor Dunaliella salina cultivation system integrating a high-efficiency brine pretreatment function. Background Technology

[0002] Dunaliella salina (Dunaliella salina) Dunaliella salina Dunaliella salina is a highly economically valuable halophilic single-celled microalga that can accumulate large amounts of natural products such as β-carotene under specific conditions, showing broad application prospects in health products, cosmetics, and food additives. Utilizing natural or industrial by-product brine for Dunaliella salina cultivation allows for the high-value utilization and ecological treatment of brine resources, representing an important direction for the coordinated development of the Dunaliella salina industry and the salt chemical industry. However, heavy metal pollution in the brine is currently the biggest problem in domestic Dunaliella salina cultivation, resulting in widespread excessive heavy metal content in Dunaliella salina products on the domestic market.

[0003] The cultivation of Dunaliella salina using brine generally includes the following steps: brine collection and storage, brine pretreatment, inoculation and initial cultivation, large-scale outdoor cultivation, harvesting and concentration, dehydration and drying, product processing and storage, and wastewater treatment and recycling. Among these, brine pretreatment is a crucial step, aiming to remove harmful organisms, heavy metal ions, suspended impurities, and other contaminants from the original brine to ensure the healthy growth of Dunaliella salina and the safety of the products.

[0004] In existing technologies, brine pretreatment often employs a multi-stage, separate process combination. For example, a typical process includes: sequentially disinfecting the brine in a shaded, sealed environment; removing chlorine through open-air sun exposure; adding alkali to form magnesium hydroxide colloids to adsorb heavy metals; and micron-level precision filtration. While effective, this process has significant drawbacks: it is lengthy, requiring the construction of multiple independent structures such as disinfection tanks, aeration tanks, reaction tanks, and sedimentation tanks, resulting in high equipment investment and energy consumption. Furthermore, it relies on large-area open-air sun exposure ponds, making it difficult to implement in areas with limited land resources or frequent rainy weather, significantly impacting its economic viability and operability in large-scale outdoor aquaculture scenarios.

[0005] In addition, there are also advanced treatment solutions for specific pollutants in the existing technology. For example, Chinese patent CN110066042A, "Method and System for Reducing Arsenic in Brine for Dunaliella Aquaculture", includes the following methods: 1) pre-oxidation precipitation, 2) preparation of calcium hydroxide solution, 3) secondary precipitation, 4) preparation of calcium carbonate slurry, and 5) accelerated flocculation precipitation; the system includes a ferric chloride storage tank, a calcium hydroxide solution preparation system, a calcium carbonate slurry preparation system, and a stirring treatment tank. Arsenic in arsenic-containing brine is separated through primary oxidation, secondary oxidation, and flocculation sedimentation, achieving a significant reduction in arsenic content to below 0.004 mg / L. The arsenic content in the Dunaliella salina cultivated using this method is reduced to below 3.0 mg / kg after harvesting and processing, improving the product quality. Simultaneously monitoring the impact of brine changes on Dunaliella salina cultivation ensures that the quality and yield of the algae are not compromised. A well-designed treatment system allows for the orderly implementation of arsenic reduction. However, the pretreatment processes (such as simple chemical disinfection or deep treatment for single heavy metals) lack an integrated and efficient purification process for complex outdoor brine (containing multiple impurities and microorganisms).

[0006] In summary, there is currently a lack of a brine pretreatment system that can adapt to large-scale outdoor aquaculture scenarios, integrates efficient disinfection, dechlorination, heavy metal removal, and deep filtration, and is not dependent on specific climatic conditions. Therefore, there is an urgent need to develop a highly integrated, compact, and automated outdoor Dunaliella salina cultivation system based on brine resources. This system could significantly shorten the brine pretreatment process, reduce the investment cost of pretreatment equipment, and thus promote the large-scale development of the Dunaliella salina cultivation industry. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-efficiency outdoor cultivation system for Dunaliella salina based on brine resources.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A highly efficient outdoor Dunaliella salina cultivation system based on brine resources includes a brine collection and storage module, a brine pretreatment module, an inoculation and initial cultivation module, and a large-scale outdoor cultivation module connected in sequence. The brine pretreatment module includes a raw brine buffer tank, a purification tank, and a nutrient salt mixing tank connected in sequence. The raw brine buffer tank is equipped with a foaming device, a heating device, and an electrochemical disinfection device. A conveying pipeline equipped with a solenoid valve connects the raw brine buffer tank and the purification tank. The raw brine buffer tank is equipped with a free chlorine sensor to detect the chlorine content in the brine. The free chlorine sensor is connected to the solenoid valve on the conveying pipeline via a controller. When the free chlorine sensor detects that the chlorine content in the raw brine buffer tank is below a preset threshold, the controller controls the solenoid valve to open, allowing the brine to enter the mixing zone of the purification tank. The purification tank is equipped with an alkaline solution for adsorbing heavy metals from the brine and a retaining screen for initially removing impurities. The retaining screen divides the purification tank into a mixing zone and a purification zone. The alkaline solution is placed in the mixing zone. A microfiltration device is installed between the nutrient salt mixing tank and the purification tank. The purification zone of the purification tank is connected to an outlet pipe, which is connected to the input end of the microfiltration device. The output end of the microfiltration device is connected to the nutrient salt mixing tank. The heating device is a plate heat exchanger or an electric heating jacket, and the electrochemical disinfection device is an iron-carbon internal electrolysis component or a low-voltage electric field sterilizer.

[0009] Further configured, the alkaline solution is a magnesium hydroxide solution used to adsorb heavy metal impurities in the brine to form magnesium hydroxide colloid, the bottom of the purification tank is equipped with a sludge hopper and a sludge discharge pipe connected to the sludge hopper, and a sludge discharge valve is installed on the sludge discharge pipe for periodically discharging magnesium hydroxide-heavy metal composite sludge, and a foaming device is also provided in the mixing zone of the purification tank to ensure that the alkaline solution and heavy metal impurities are in full contact, and the foaming devices in the original brine buffer tank and the purification tank are both micro-nano bubble generators.

[0010] Further configured, a feeding tank for storing magnesium hydroxide solution, a discharge pipe connected to the feeding tank, and a metering pump installed at the output end of the discharge pipe are provided next to the purification tank. The metering pump is connected to the mixing zone through a pipe. A pH sensor for detecting the pH value of the mixing zone is installed in the mixing zone of the purification tank. The pH sensor is connected to the metering pump through a controller so that the metering pump controls and adjusts the amount of magnesium hydroxide solution added according to the signal feedback from the pH sensor to maintain the pH in the purification tank at 8.5–10.5, so as to promote the adsorption of heavy metals and the formation of colloids.

[0011] The microfiltration device is further configured to include a filter housing and a diaphragm pump, wherein the input end of the diaphragm pump is connected to the outlet of the purification zone through an outlet pipe, and is used to pump brine into the filter housing. The filter box is equipped with a heavy metal adsorption packing layer and a microfiltration membrane in sequence along the brine flow direction. The output end of the filter box is connected to the nutrient salt mixing tank through a pipe. The pore size of the microfiltration membrane is 0.1–1.0 μm, and the membrane material is PVDF or PTFE.

[0012] A further configuration is provided, wherein the filter housing includes a door that facilitates opening the filter housing to maintain the heavy metal adsorption packing layer and the microfiltration membrane, and the door is located at the top of the filter housing.

[0013] Further configured, the heavy metal adsorption filler layer is filled with surface-modified zeolite or chitosan-supported adsorption material.

[0014] A further feature is that the intercepting mesh plate in the purification tank is a wedge-shaped stainless steel mesh, and the intercepting mesh plate is detachably connected to the purification tank so as to facilitate the removal of the intercepting mesh plate for subsequent cleaning and maintenance.

[0015] A further configuration is provided, wherein the edge of the intercepting mesh plate is fitted with a rubber ring that abuts against the inner wall of the purification tank, and the inner wall of the purification tank is inclined toward the sludge hopper.

[0016] By adopting the above technical solution, the beneficial effects of the present invention are as follows: 1. High integration, compact process, and reduced investment: By integrating disinfection, dechlorination, and homogenization functions into the original brine buffer tank, and coagulation and sedimentation functions into the purification tank, the brine pretreatment process is significantly shortened, reducing the need for multiple independent structures and special equipment, thereby reducing the system's footprint and infrastructure investment costs.

[0017] 2. Eliminating reliance on open-air exposure and enabling all-weather operation: By adopting an electrochemical disinfection device, a micro-nano bubble generator, and automatic control based on a free chlorine sensor, the reliance on open-air exposure is eliminated, enabling stable operation of brine pretreatment in all weather conditions and regions, significantly improving operability and economy in large-scale outdoor aquaculture scenarios.

[0018] 3. Multi-stage synergy for thorough purification: By constructing a multi-stage synergistic purification process consisting of disinfection and dechlorination, chemical coagulation and adsorption, physical interception and deep filtration and adsorption, it can integrate and efficiently remove various impurities such as microorganisms, heavy metals and suspended solids in brine, producing water of excellent quality and providing a stable and reliable cultivation water source for Dunaliella salina.

[0019] 4. Intelligent control and convenient maintenance: Through the coordinated control of free chlorine sensors, pH sensors, and corresponding valves and pumps, key process parameters are automatically monitored and adjusted, improving processing efficiency and stability. Meanwhile, the detachable filter screen and filter housing with maintenance door make cleaning and replacement of key components easier, reducing long-term maintenance costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0021] Figure 2 A schematic diagram showing the structure of the brine buffer tank, purification tank, and nutrient salt mixing tank.

[0022] Figure 3 This is a schematic diagram of the structure of the diaphragm pump and the filter housing.

[0023] Figure 4 This is a schematic diagram of the structure of the purification tank and the feeding tank.

[0024] In the diagram: raw brine buffer tank 100, purification tank 200, nutrient salt mixing tank 300, foaming device 1, heating device 2, electrochemical disinfection device 3, conveying pipeline 4, free chlorine sensor 5, interception screen 6, mixing zone 201, purification zone 202, microfiltration device 400, liquid outlet pipe 7, sludge hopper 8, sludge discharge pipe 9, feeding tank 10, discharge pipe 11, metering pump 12, pH sensor 13, filter box 14, diaphragm pump 15, heavy metal adsorption packing layer 16, microfiltration membrane 17, box door 141, rubber ring 61. Detailed Implementation

[0025] Reference Figures 1 to 4 The embodiments of the present invention will be further described below. The core of the system of the present invention lies in its highly integrated brine pretreatment module, which connects with the subsequent aquaculture module to form a complete outdoor aquaculture system.

[0026] A highly efficient outdoor Dunaliella salina cultivation system based on brine resources includes a brine collection and storage module, a brine pretreatment module, an inoculation and initial cultivation module, and a large-scale outdoor cultivation module connected in sequence. The brine pretreatment module includes a raw brine buffer tank 100, a purification tank 200, and a nutrient salt mixing tank 300 connected in sequence. The raw brine buffer tank 100 is equipped with a foaming device 1, a heating device 2, and an electrochemical disinfection device 3. The purification tank 200 is equipped with an alkaline solution for adsorbing heavy metals in the brine and a retaining mesh plate 6 for initially intercepting impurities. The retaining mesh plate 6 is a wedge-shaped stainless steel mesh. The retaining mesh plate 6 divides the purification tank 200 into a mixing zone 201 and a purification zone 202. The alkaline solution is placed in the mixing zone 201. The mixing zone 201 of the purification tank 200 is also equipped with a foaming device 1 to ensure that the alkaline solution and heavy metal impurities are in full contact. The alkaline solution is a magnesium hydroxide solution used to adsorb heavy metal impurities in the brine to form magnesium hydroxide colloid. The bottom of the purification tank 200 is equipped with a sludge hopper 8 and a sludge discharge pipe 9 connected to the sludge hopper 8. A sludge discharge valve (not shown in the figure) is installed on the sludge discharge pipe 9 for periodically discharging magnesium hydroxide-heavy metal composite sludge.

[0027] Both the original brine buffer tank 100 and the purification tank 200 contain micro-nano bubble generators. The micro-nano bubble generator in the original brine buffer tank 100 is used to enhance the removal of residual chlorine, gas-liquid mass transfer and brine homogenization. The bubble generator in the purification tank 200 is used to promote the uniform dispersion of magnesium hydroxide and the rapid complexation / adsorption of heavy metals, shorten the reaction time and improve the removal efficiency.

[0028] Heating device 2 is a plate heat exchanger or electric heating jacket, used to maintain the brine in a suitable pretreatment temperature range of 25–35℃ to improve the efficiency of electrochemical disinfection and coagulation / adsorption; electrochemical disinfection device 3 is an iron-carbon internal electrolysis component or a low-voltage electric field sterilizer, used for efficient and broad-spectrum microbial control of the brine.

[0029] A conveying pipe 4 with a solenoid valve connects the raw brine buffer tank 100 and the purification tank 200. The raw brine buffer tank 100 is equipped with a free chlorine sensor 5 for detecting the chlorine content in the brine. The free chlorine sensor 5 is connected to the solenoid valve on the conveying pipe 4 via a controller (PLC). When the controller detects that the chlorine content in the raw brine buffer tank 100 has dropped below a preset threshold (chlorine content 0.1 mg / L, which is lower than the concentration that inhibits algae growth), it controls the solenoid valve to open so that the brine enters the mixing zone 201 of the purification tank 200.

[0030] A microfiltration device 400 is installed between the nutrient salt preparation tank 300 and the purification tank 200. The purification zone 202 of the purification tank 200 is connected to the outlet pipe 7. The microfiltration device 400 includes a filter box 14 and a diaphragm pump 15. The input end of the diaphragm pump 15 is connected to the outlet of the purification zone 202 through the outlet pipe 7, and is used to pump brine into the filter box 14. The filter box 14 is provided with a heavy metal adsorption packing layer 16 and a microfiltration membrane 17 in sequence along the brine flow direction. The output end of the filter box 14 is connected to the nutrient salt preparation tank 300 through a pipe. The pore size of the microfiltration membrane 17 is 0.1–1.0 μm, preferably 0.2 μm, and the membrane material is PVDF or PTFE. The heavy metal adsorption packing layer 16 is filled with surface-modified zeolite, such as hydrogen-type clinoptilolite or sodium-type mordenite, for further adsorption of residual lead, cadmium and other ions and removal of ammonium salts. When the arsenic content in the brine is known to be high, the heavy metal adsorption packing layer 16 is preferably filled with a chitosan-supported adsorption material, such as a chitosan-iron composite adsorption material, for the specific adsorption of anionic heavy metals such as arsenates. The filter housing 14 includes a door 141 that facilitates opening the filter housing 14 for maintenance of the heavy metal adsorption packing layer 16 and the microfiltration membrane 17, and the door 141 is located at the top of the filter housing 14.

[0031] Working principle: The brine enters the original brine buffer tank 100, where electrochemical disinfection and micro-nano bubble dechlorination work together. Specifically, the electrochemical disinfection device 3 (taking an iron-carbon internal electrolysis component as an example, with parameters of 1:1 iron-carbon mass ratio, 3V±0.5V working voltage, 5mA / cm² current density, cast iron / graphite electrode material, and 20 minutes processing time) performs efficient and broad-spectrum instantaneous sterilization on the brine, eliminating harmful microorganisms at the source. At the same time, the micro-nano bubble generator produces a large number of extremely small bubbles. Their huge specific surface area and slow rising speed can greatly enhance the gas-liquid mass transfer efficiency. This not only promotes the homogenization of the brine but also accelerates the dissipation of free chlorine (residual chlorine) in the water into the atmosphere. Compared with "open-air exposure" that relies on sunlight and natural diffusion, the efficiency is greatly improved.

[0032] Heating device 2 (This invention takes a plate heat exchanger as an example, with the following parameters: heat transfer coefficient ≥3500 W / (m²)) 2 The plate material is 316L stainless steel, and the design pressure is 1.0MPa. It maintains the brine at the optimal reaction temperature of 25–35℃, while improving the efficiency of electrochemical disinfection and subsequent coagulation and adsorption kinetics. The heating device 2 heats the brine and, together with the micro-nano bubble generator, enhances gas-liquid mass transfer, further accelerating the release of free chlorine (residual chlorine) in the water into the atmosphere.

[0033] Furthermore, the integrated free chlorine sensor 5, along with the controller and solenoid valve, forms an intelligent closed loop: when the sensor detects that the residual chlorine content has dropped to a safe threshold that is harmless to Dunaliella salina (e.g., ≤0.1mg / L), the controller automatically opens the solenoid valve, precisely delivering the pretreated brine to the next stage. This invention highly integrates the traditionally dispersed disinfection, dechlorination, and homogenization processes through the original brine buffer tank 100, shortening the brine pretreatment process and replacing the two sets of facilities in the traditional process: the "shaded and sealed disinfection tank" and the "large-area open-air exposure tank," thus reducing equipment investment costs.

[0034] This invention utilizes a smart closed loop consisting of a feeding tank 10, a metering pump 12, and a pH sensor 13 to automatically add magnesium hydroxide solution to the mixing zone 201 and precisely control the pH within the optimal range of 8.5–10.5. In this alkaline environment, magnesium hydroxide rapidly forms a colloid with a large surface charge, which can efficiently trap various heavy metal ions such as lead, arsenic, and copper through adsorption, co-precipitation, and ion exchange. The micro-nano bubble generator within the purification tank 200 further agitates the colloid, ensuring sufficient contact between the colloid and the heavy metal ions, significantly shortening the reaction time. The generated magnesium hydroxide-heavy metal composite colloid is initially intercepted and enriched by the wedge-shaped stainless steel mesh interception plate 6 when it flows into the purification zone 202. The wedge-shaped structure of the interception plate 6 is not easily clogged, and the intercepted flocs easily slide off under gravity. The bottom of the purification tank 200 is designed with an inner wall that slopes towards the sludge hopper 8. Combined with the auxiliary disturbance of microbubbles, the heavier flocs and colloids can quickly settle and collect in the sludge hopper 8, which is convenient for periodic discharge through the sludge discharge valve. This design in the present invention combines the functions of the traditional "reaction tank" and "sedimentation tank" and realizes the directional enrichment and convenient removal of heavy metal pollutants.

[0035] The supernatant from purification zone 202 is pumped into microfiltration unit 400 via diaphragm pump 15. The brine first flows through a heavy metal adsorption packing layer 16 composed of surface-modified zeolite or chitosan-supported adsorption materials. These two materials have extremely strong selective adsorption capacity for low concentrations of specific types of heavy metal ions (e.g., surface-modified zeolite for ammonium ions and some heavy metals, and chitosan composite materials for arsenic, chromium, etc.), serving as an important supplement and safeguard against the upstream magnesium hydroxide adsorption. Subsequently, the brine passes through a PVDF or PTFE microfiltration membrane 17 with a pore size of 0.1–1.0 μm. This membrane can 100% retain residual suspended particles, bacteria, fine colloids, and large organic molecules, ensuring clear and sterile effluent. The design of the door 141 on the top of the filter housing 14 makes the replacement of the adsorption packing and the cleaning and maintenance of the microfiltration membrane 17 exceptionally simple, ensuring long-term stable operating efficiency of the unit and reducing long-term maintenance costs.

[0036] In summary, this invention highly integrates multiple independent processes in traditional processes, such as "shading disinfection," "open-air sun exposure for chlorination," "reaction tank," and "sedimentation tank," into two core modules: the raw brine buffer tank 100 and the purification tank 200. Through the coordinated operation of electrochemical disinfection, micro-nano bubble chlorination, and heating, it replaces open-air sun exposure. This not only significantly shortens the process flow and reduces the number of specialized structures and equipment, but also directly reduces land occupation and infrastructure investment. Secondly, this invention employs electrochemical disinfection, micro-nano bubble-enhanced mass transfer, and automatic control technologies such as the free chlorine sensor 5, achieving stable operation of the pretreatment process around the clock and in all regions. This completely eliminates dependence on weather and land resources, greatly improving the economics and operability of large-scale outdoor aquaculture, while significantly improving processing efficiency through automated control. Finally, this invention constructs a multi-level synergistic purification chain of "disinfection and dechlorination → chemical coagulation and adsorption → physical interception → deep filtration and adsorption", forming an efficient and integrated purification process for complex brine containing bacteria, heavy metals and suspended solids, producing comprehensive and thorough water quality, and providing a stable and high-quality culture medium for Dunaliella salina cultivation.

[0037] A feeding tank 10 for storing magnesium hydroxide solution, a discharge pipe 11 connected to the feeding tank 10, and a metering pump 12 installed at the output end of the discharge pipe 11 are provided next to the purification tank 200. The metering pump 12 is connected to the mixing zone 201 through a pipe. A pH sensor 13 for detecting the pH value of the mixing zone 201 is installed in the mixing zone 201 of the purification tank 200. The pH sensor 13 is connected to the metering pump 12 through a controller so that the metering pump 12 controls and adjusts the amount of magnesium hydroxide solution added according to the signal feedback from the pH sensor 13. The pH in the purification tank 200 is 8.5–10.5 to promote the adsorption of heavy metals and the formation of colloids.

[0038] pH sensor 13 provides real-time feedback on the acidity or alkalinity of mixing zone 201, and the controller dynamically adjusts the dosage of metering pump 12 to ensure that the reaction is always within the optimal pH window (8.5–10.5), achieving precise and automated dosing of magnesium hydroxide solution. This design not only maximizes the removal rate of heavy metals but also avoids waste, increased salinity, and potential contamination of the subsequent microfiltration membrane 17 caused by excessive alkali addition.

[0039] The inner wall of the purification tank 200 is inclined towards the sludge hopper 8. This structure guides the sediment to slide naturally into the sludge hopper 8 in the center of the tank, greatly improving the efficiency of sludge accumulation and discharge, reducing sludge buildup at the bottom of the tank, and lowering the frequency of tank cleaning and labor intensity. It also facilitates a tighter contact between the rubber ring 61 and the inner wall of the purification tank 200 as it is continuously pressed downwards, which helps to improve the installation stability of the intercepting mesh plate 6.

[0040] The edge of the intercepting mesh plate 6 is fitted with a rubber ring 61 that abuts against the inner wall of the purification tank 200 so that the intercepting mesh plate 6 can be disassembled and connected to the purification tank 200. This makes it easy to remove the intercepting mesh plate 6 for later cleaning and maintenance, remove attachments, and prevent the intercepting mesh plate 6 from clogging and affecting its use.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0042] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] The control method of this invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Furthermore, since this invention is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency outdoor Dunaliella salina cultivation system based on brine resources, comprising a brine collection and storage module, a brine pretreatment module, an inoculation and initial culture module, and a large-scale outdoor cultivation module connected in sequence, wherein the brine pretreatment module comprises a raw brine buffer tank (100), a purification tank (200), and a nutrient salt preparation tank (300) connected in sequence, characterized in that: The original brine buffer tank (100) is equipped with a foaming device (1), a heating device (2) and an electrochemical disinfection device (3). The original brine buffer tank (100) and the purification tank (200) are connected by a conveying pipe (4) with a solenoid valve. The original brine buffer tank (100) is equipped with a free chlorine sensor (5) for detecting the chlorine content in the brine. The free chlorine sensor (5) is connected to the solenoid valve on the conveying pipe (4) through a controller. When the controller detects that the chlorine content in the original brine buffer tank (100) is lower than a preset threshold, it controls the solenoid valve to open so that the brine enters the mixing zone (201) of the purification tank (200). The purification tank (200) is equipped with an alkaline solution for adsorbing heavy metals in the brine and a retaining screen (6) for initially retaining impurities. The retaining screen (6) divides the purification tank (200) into a mixing zone (201) and a purification zone (202). The alkaline solution is placed in the mixing zone (201). A microfiltration device (400) is provided between the nutrient salt preparation tank (300) and the purification tank (200). The purification zone (202) of the purification tank (200) is connected to an outlet pipe (7). The outlet pipe (7) is connected to the input end of the microfiltration device (400). The output end of the microfiltration device (400) is connected to the nutrient salt preparation tank (300). The heating device (2) is a plate heat exchanger or an electric heating jacket, and the electrochemical disinfection device (3) is an iron-carbon internal electrolysis component or a low-voltage electric field sterilizer.

2. The efficient outdoor cultivation system for Dunaliella salina based on brine resources according to claim 1, characterized in that, The alkaline solution is a magnesium hydroxide solution used to adsorb heavy metal impurities in the brine to form magnesium hydroxide colloid. The bottom of the purification tank (200) is equipped with a sludge hopper (8) and a sludge discharge pipe (9) connected to the sludge hopper (8). A sludge discharge valve is installed on the sludge discharge pipe (9) for periodically discharging magnesium hydroxide-heavy metal composite sludge. A foaming device (1) is also provided in the mixing zone (201) of the purification tank (200) to ensure that the alkaline solution and heavy metal impurities are in full contact. The foaming devices (1) in the original brine buffer tank (100) and the purification tank (200) are both micro-nano bubble generators.

3. The high-efficiency outdoor cultivation system for Dunaliella salina based on brine resources according to claim 2, characterized in that, Next to the purification tank (200) is a feeding tank (10) for storing magnesium hydroxide solution, a discharge pipe (11) connected to the feeding tank (10), and a metering pump (12) installed at the output end of the discharge pipe (11). The metering pump (12) is connected to the mixing zone (201) through a pipe. A pH sensor (13) for detecting the pH value of the mixing zone (201) is installed in the mixing zone (201) of the purification tank (200). The pH sensor (13) is connected to the metering pump (12) through a controller so that the metering pump (12) controls and adjusts the amount of magnesium hydroxide solution added according to the signal feedback from the pH sensor (13). The pH in the purification tank (200) is 8.5–10.5 to promote the adsorption of heavy metals and the formation of colloids.

4. The efficient outdoor cultivation system for Dunaliella salina based on brine resources according to claim 1, characterized in that, The microfiltration device (400) includes a filter box (14) and a diaphragm pump (15). The input end of the diaphragm pump (15) is connected to the outlet of the purification zone (202) through the outlet pipe (7) to pump brine into the filter box (14). The filter box (14) is provided with a heavy metal adsorption packing layer (16) and a microfiltration membrane (17) in sequence along the brine flow direction. The output end of the filter box (14) is connected to the nutrient salt mixing tank (300) through a pipe. The pore size of the microfiltration membrane (17) is 0.1–1.0 μm and the membrane material is PVDF or PTFE.

5. The high-efficiency outdoor cultivation system for Dunaliella salina based on brine resources according to claim 4, characterized in that, The filter housing (14) includes a door (141) for easy opening of the filter housing (14) to maintain the heavy metal adsorption packing layer (16) and the microfiltration membrane (17), and the door (141) is located on the top of the filter housing (14).

6. The high-efficiency outdoor cultivation system for Dunaliella salina based on brine resources according to claim 4, characterized in that, The heavy metal adsorption filler layer (16) is filled with surface-modified zeolite or chitosan-supported adsorption material.

7. The efficient outdoor cultivation system for Dunaliella salina based on brine resources according to claim 1, characterized in that, The intercepting mesh plate (6) in the purification tank (200) is a wedge-shaped stainless steel mesh. The intercepting mesh plate (6) is detached and connected in the purification tank (200) so that the intercepting mesh plate (6) can be removed for later cleaning and maintenance.

8. The high-efficiency outdoor cultivation system for Dunaliella salina based on brine resources according to claim 8, characterized in that, The edge of the intercepting mesh plate (6) is fitted with a rubber ring (61) that abuts against the inner wall of the purification tank (200), and the inner wall of the purification tank (200) is inclined toward the sludge hopper (8).

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