Seawater shrimp and crab culture pond water circulation purification system and utilization method thereof

Abstract

The present application belongs to the field of aquaculture engineering, and relates to a seawater shrimp and crab breeding pond water circulation and purification system and a utilization method. The system comprises a breeding pond, a filter dam, a biological filter pond, an ecological regulation pond and a disinfection and backflow unit connected in sequence to form a circulation loop; the ecological regulation pond is divided into a filter-feeding organism pond and a large algal pond and is connected through an adjustable weir gate; the system is provided with a central controller which can dynamically regulate the hydraulic retention time and the backflow injection depth according to water quality and water temperature data, realizes water self-purification and water temperature stratified management, and reduces water exchange demand and environmental pollution.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture engineering and relates to a water circulation and purification system and its utilization method for marine shrimp and crab farming ponds. Background Technology

[0002] Marine shrimp and crab pond farming is an important aquaculture model in my country. However, the traditional open-type farming model mainly relies on large-scale water exchange to maintain water quality. This not only consumes a lot of water resources, but also directly discharges aquaculture wastewater rich in pollutants such as uneaten feed, feces, and ammonia nitrogen into the external environment, causing serious pollution of the aquaculture itself and eutrophication of the surrounding water bodies.

[0003] To reduce water changes, recirculating aquaculture systems (RAS) have been introduced. The core of this technology is the purification and recycling of water within the system through a series of water treatment units (such as physical filtration, biological filtration, and disinfection). However, existing RAS technologies are mostly focused on intensive indoor aquaculture. Their system construction and operation are energy-intensive, equipment maintenance is complex, and investment costs are huge, making them difficult to promote in large-scale open-air pond aquaculture. Furthermore, traditional RAS systems often operate with fixed processes, lacking the refined utilization of the water's ecological purification potential (such as shellfish filter feeding and algal absorption), and cannot effectively address the temperature stratification problem caused by changes in light and air temperature. Temperature stratification can lead to hypoxia at the bottom, posing a serious threat to benthic shrimp and crab organisms.

[0004] Therefore, there is an urgent need in this field for an aquaculture system and method that can achieve efficient water circulation and purification, reduce dependence on the external environment, be suitable for open ponds, have low operating costs, and can intelligently regulate the physical and ecological state of the water. Summary of the Invention

[0005] This patent aims to provide a circulating purification system and method for marine shrimp and crab aquaculture ponds. By integrating physical, biological and ecological regulation units and introducing intelligent control, the system achieves self-purification and recycling of aquaculture water, thereby reducing the need for water exchange and environmental pollution.

[0006] A water circulation and purification system for marine shrimp and crab farming ponds includes: Aquaculture ponds are used for raising shrimp and crabs. The filter dam has its inlet connected to the drain outlet of the aquaculture pond, and is filled with one or more filter media selected from zeolite, coral stone, or ceramsite. A biological filter, the inlet of which is connected to the outlet of a filter dam, is filled with biological packing material for attaching microorganisms; The ecological regulation pond has its inlet connected to the outlet of the biological filter. The outlet of the biological filter has a sluice gate, which can be opened when needed to allow water to flow from the biological filter into the ecological regulation pond. The ecological regulation pond is divided into a filter-feeding organism pond and a large algae pond. Oysters or mussels are suspended in the filter-feeding organism pond, while Gracilaria or Pteris vittata is planted in the large algae pond. The filter-feeding organism pond and the large algae pond are connected by a first adjustable weir gate. The disinfection reflux unit has its inlet connected to the outlet of the ecological regulation pond, and its outlet returns to the aquaculture pond through a pipeline, forming a circulation loop. And a central controller, which connects to multiple actuators and sensor signals within the system.

[0007] This system organically integrates multiple treatment units, including physical filtration (filter dam), biodegradation (biofilter), ecological regulation (ecological regulation pond), and disinfection and sterilization (disinfection reflux unit), to construct a complete water circulation path of "aquaculture pond - purification unit - aquaculture pond". This structure fundamentally changes the traditional aquaculture model that relies on large-scale water exchange and sewage discharge, realizing internal circulation and self-purification of the aquaculture water, significantly improving water resource utilization efficiency, and effectively reducing pollution discharge to external water bodies.

[0008] The filter dam is a dam structure spanning the water flow channel, internally divided into at least three filter chambers arranged in series along the water flow direction. The coarse filter chamber is filled with 10–30 mm diameter ceramic pebbles or volcanic rock to trap large suspended solids in the water; the adsorption chamber is filled with 5–15 mm diameter zeolite to adsorb ammonia nitrogen and heavy metal ions; and the buffer chamber is filled with 20–40 mm diameter coral stone to stabilize the water's pH and provide trace elements for subsequent biological treatment. The filter chambers are separated by perforated partitions with pore sizes smaller than the minimum particle size of the filter media in the preceding chamber to prevent cross-contamination. This tiered configuration of different filter media types and particle sizes achieves progressive filtration from coarse to fine, effectively delaying filter bed clogging and extending the cleaning cycle.

[0009] Biological filters are treatment structures designed to enhance aerobic nitrification. They feature aeration holes at the bottom and are filled with a combination of high-surface-area biological packing materials, such as suspended ball packing and elastic three-dimensional packing, providing ample attachment surfaces for aerobic microorganisms like nitrifying and nitrite-oxidizing bacteria. The aeration holes are connected to an external blower for continuous oxygen supply, maintaining a dissolved oxygen concentration above 4 mg / L to ensure efficient and stable nitrification.

[0010] The ecological regulation pond includes a filter-feeding biological pond and a large algae pond. The filter-feeding biological pond is equipped with multi-layered, three-dimensional suspended culture racks for suspending oyster or mussel farming strings; the large algae pond contains hydroponic algae floating boards for fixing and cultivating algae such as Gracilaria or Gynostemma pentaphyllum. The multi-layered, three-dimensional suspended culture racks and floating raft cultivation system significantly increase the biological load density per unit water volume, enhancing the water purification capacity, and is particularly suitable for situations with limited land resources. Utilizing the "shellfish-algae" symbiotic ecological principle, it removes particulate organic matter (such as phytoplankton and organic debris) and dissolved nutrients (such as nitrogen and phosphorus) from the water, achieving the biological absorption and transformation of pollutants and realizing the resource utilization of pollutants.

[0011] The disinfection and return unit is located at the end of the system. It performs final disinfection on the purified water, kills pathogenic microorganisms, blocks the transmission of diseases, and ensures the biological safety of the returned water.

[0012] The system also features a central controller, which connects to all actuators and sensors, providing a foundation for automated operation and precise control. Based on real-time monitoring of water quality, temperature, and other parameters, the central controller can dynamically adjust the operating status of each unit, thereby upgrading from fixed-process operation to intelligent response control, significantly improving the system's purification efficiency and operational stability.

[0013] This marine shrimp and crab aquaculture pond water circulation and purification system features inlet and outlet gates on the side walls of the pond. The bottom height gradually decreases from the inlet to the outlet. A filter screen is installed inside the pond, with the shrimp and crab farming area above the screen and the sedimentation area below. The inlet gate is responsible for the initial water injection and replenishment during system operation; seawater is introduced from outside when the system starts up, and external water supply is activated when the water level in the pond falls below a set threshold during circulation. The gradually sloping bottom of the pond, decreasing from the inlet to the outlet, creates a stable hydraulic gradient. This design utilizes the water's own gravity to naturally drive uneaten feed, feces, and other solid waste towards the lower end of the outlet, effectively promoting the directional accumulation of pollutants towards the outlet gate and laying the structural foundation for efficient subsequent discharge. The filter screen within the pond vertically divides the water into the shrimp and crab farming area and the sedimentation area. This structure achieves in-situ preliminary solid-liquid separation: the upper aquaculture zone provides a clean activity space for shrimp and crabs, preventing secondary pollution caused by their agitation of bottom sediments; the lower sedimentation zone serves as a static settling and temporary storage container for sludge, effectively storing solid waste. When the drain gate is opened, the bottom sludge can first enter the filter dam and then the biological filter. The configuration of the inlet and outlet gates gives the system the dynamism of adjustable circulation flow, allowing for precise control according to the water quality requirements of different aquaculture stages. The structural slope of the pond bottom, combined with functional zoning, creates a self-cleaning aquaculture environment, reducing the frequency and labor intensity of cleaning, while also minimizing water disturbance.

[0014] This marine shrimp and crab aquaculture pond water circulation and purification system includes water quality monitoring modules in the filter-feeding biological pond and the large algae pond for real-time monitoring of total nitrogen, total phosphorus, and chlorophyll a content. The disinfection and recirculation unit includes a recirculation pipe connected to the large algae pond via a second adjustable weir. The water quality monitoring modules are signal-connected to a central controller, which dynamically adjusts the opening of the first and second adjustable weirs based on water quality data to control the hydraulic residence time of water in the filter-feeding biological pond and the large algae pond. By incorporating online water quality monitoring modules in the filter-feeding biological pond and the large algae pond and connecting them to the central controller, this system constructs a real-time sensing and feedback control closed loop for key water quality parameters (total nitrogen, total phosphorus, and chlorophyll a). This allows the system to transcend traditional fixed-mode operation, dynamically adjusting according to actual water quality conditions, achieving an upgrade from experience-driven to data-driven operation.

[0015] By dynamically and independently adjusting the openings of the first and second adjustable weirs, the central controller can precisely control the hydraulic retention time (HRT) of the filter-feeding biological pond and the large algae pond, respectively. When the suspended particulate matter (in the form of chlorophyll a or turbidity) content in the water is high, the system can significantly extend the HRT in the filter-feeding biological pond by reducing the opening of the first adjustable weir and coordinating with the second adjustable weir, thereby enhancing the filter feeding of shellfish. When the dissolved nutrients (total nitrogen and total phosphorus) content is high, the system can preferentially extend the HRT in the large algae pond by adjusting the combination of the openings of the two weirs, thereby enhancing the absorption of nutrients by algae.

[0016] This independent and coordinated control mechanism of the hydraulic retention time (HRT) of the two ecological purification units ensures that both shellfish and algae biological purification methods operate at their most efficient levels, achieving synergistic effects between subsystems. This design endows the ecological control tank with "intelligent scheduling" capabilities, responding to water quality fluctuations caused by feeding, biological activity, and temperature changes. By adjusting the hydraulic retention time in real time and with precision, the system can proactively mitigate peak water quality loads, preventing overload of any purification unit and maintaining stable effluent quality. This provides a continuous supply of high-quality recycled water to the aquaculture tank, effectively protecting the living environment of the cultured organisms.

[0017] In the water circulation and purification system of marine shrimp and crab farming ponds, the central controller is configured to execute a dynamic allocation algorithm for the hydraulic retention time of the ecological regulation pond. The steps of this algorithm are as follows: According to claim 3, in a marine shrimp and crab aquaculture pond water circulation and purification system, the central controller is configured to execute a dynamic allocation algorithm for the hydraulic retention time of the ecological regulation pond, the steps of which are as follows: S1: The water quality monitoring module obtains water quality parameters representing suspended solids and nutrient load inside the ecological regulation pond, mainly monitoring the total suspended particulate matter concentration and total nitrogen concentration in the filter-feeding biological pond and the large algae pond. S2: The optimization objective is to optimize the synergistic removal efficiency of the system for suspended solids and nutrients. The focus of the objective can be dynamically adjusted according to the farming stage. An objective function with the system's total nitrogen removal rate and total suspended solids removal rate as dual objectives is constructed, and weighting factors that are automatically adjusted according to different growth stages of shrimp and crabs are introduced. S3: Input the acquired water quality parameters into a neural network model. The model outputs the optimal hydraulic retention time allocation instruction corresponding to the current water quality condition. The neural network model is a BP neural network. S4: The central controller automatically adjusts the opening of the first and second adjustable weir gates set in the ecological control pool according to the instructions.

[0018] The central controller, employing a pre-trained BP neural network model, can process complex, multi-dimensional, and nonlinear water quality data such as total suspended particulate matter (TSP) concentration, total nitrogen (TNP) concentration, and water temperature, and outputs the optimal hydraulic retention time allocation ratio. This allows the system to transcend traditional control modes that rely on fixed parameters or human experience, achieving data-driven intelligent decision-making and significantly improving the scientific rigor and accuracy of regulation. The algorithm constructs a dual objective function with the system's TNP removal rate and TNP removal rate, and innovatively introduces weighting factors that are automatically adjusted according to different growth stages of shrimp and crabs. This enables the system to dynamically balance the load on the two major purification pathways of "shellfish filter feeding" and "algae absorption," precisely adjusting the control focus at different stages of aquaculture (such as early-stage dissolved oxygenation and later-stage nitrogen and phosphorus removal), achieving adaptive matching between purification strategies and aquaculture processes, thereby maintaining optimal purification efficiency throughout the entire aquaculture cycle. The BP neural network model has strong nonlinear mapping capabilities and fault tolerance, effectively handling the complex situation of multiple coupled and fluctuating water quality parameters in aquaculture water. Through real-time calculation and decision-making by this model, the system can quickly respond to instantaneous fluctuations in water quality and provide control instructions that approximate the optimal solution, thereby enhancing the system's anti-interference ability and ensuring the stability and reliability of the water quality at the outlet of the ecological control pond.

[0019] A water circulation and purification system for marine shrimp and crab aquaculture ponds is characterized by: a disinfection and return unit comprising a sealed storage tank, a return pipe connecting the sealed storage tank and a large algae pond, and a return branch pipe connecting the sealed storage tank and the aquaculture pond; an immersion-type ultraviolet disinfection lamp assembly installed within the sealed storage tank; and several liftable spray pipes arranged at the bottom of the aquaculture pond, with water from the sealed storage tank being transported to each liftable spray pipe via the return branch pipes. The immersion-type ultraviolet disinfection lamp assembly, located within the sealed storage tank, integrates disinfection functionality with water circulation power. Ultraviolet disinfection is direct and efficient in a closed environment, effectively killing pathogenic microorganisms in the water and significantly reducing the risk of disease transmission across water bodies. Simultaneously, this design uses the disinfected purified water as a power source to directly improve the flow field in the aquaculture pond, achieving multi-functionality within a single unit.

[0020] A water circulation and purification system for marine shrimp and crab aquaculture ponds is characterized by: liftable spray pipes passing through the bottom of the pond and the filter screen, with each pipe having an adjustable nozzle at its outlet. This system distributes purified water evenly throughout the pond at specific angles and directions via the liftable spray pipes. This design simulates natural water flow, effectively eliminating dead zones in water exchange, promoting full-dimensional circulation and mixing of the water, and ensuring uniformity of water quality, temperature, and dissolved oxygen, creating a more natural and healthy aquatic environment for shrimp and crab growth. The linkage between the liftable spray pipes and each nozzle allows for precise control of the injection depth. This enables the system to proactively select the optimal injection depth based on real-time monitored water temperature stratification data: either injecting from the bottom to push the lower-temperature water at the bottom upwards and break up thermal stratification; or injecting from the surface to minimize disturbance to the insulation layer. This three-dimensional control method achieves refined management of the pond's water temperature structure.

[0021] This marine shrimp and crab aquaculture pond water circulation and purification system features temperature sensor arrays spaced at equal intervals at different heights within the pond. These arrays are connected to a central controller, which adjusts the height of adjustable spray nozzles based on sensor data. This precise control of the nozzle injection depth allows for stratified temperature control or the breaking up of water stratification. By linking temperature sensor arrays at different heights within the pond with precisely adjustable nozzles, the system constructs a closed-loop, three-dimensional water temperature control system. This enables the system to perceive the thermocline structure of the water in real time and dynamically execute two distinct control strategies—maintaining beneficial stratification or breaking up harmful stratification—through precise control of injection depth and position. This fundamentally solves the problems of crude and slow-responding water temperature management in traditional aquaculture.

[0022] The marine shrimp and crab aquaculture pond water circulation and purification system features a central controller connected to a weather data receiving module. This module is configured to predict water temperature stratification trends in the pond based on received forecasts of future sunlight, air temperature, and wind speed, combined with real-time data from a temperature sensor array. It then proactively controls the nozzle injection depth to regulate the temperature stratification structure of the aquaculture water. By introducing a weather data receiving module and configuring a predictive control algorithm, the system achieves a leap from "real-time response" to "feedforward prediction." The system can predict water temperature stratification trends in advance based on future weather conditions and actively adjust nozzle injection depth to prevent or mitigate potentially stressful thermal structures for aquaculture organisms. This significantly enhances the initiative and reliability of environmental management, providing a more stable and resilient growth environment for shrimp and crabs. The combination of water temperature stratification control and backflow flow regulation based on water quality parameters achieves synergistic optimization of environmental factor control and water purification requirements. The system can intelligently decide whether to prioritize energy use to break up stratification to improve dissolved oxygen at the bottom or to maintain stratification to ensure bottom water temperature based on the actual condition of the aquaculture pond. At the same time, it matches the most suitable circulating water volume, thereby achieving the best control effect while optimizing the system's operating energy consumption.

[0023] The method for utilizing a water circulation and purification system in marine shrimp and crab farming ponds includes the following steps. System startup steps: Fill the aquaculture pond with seawater; add nitrifying and denitrifying bacteria agents to the biological filter for biofilm culture; Normal operating procedure: After the biofilm in the biological filter matures, shrimp and crab seedlings are introduced for aquaculture. The system continues to operate, and the water flows through the filter dam, biological filter, ecological regulation pond and disinfection return unit in sequence before returning to the aquaculture pond. Dynamic control steps: Using a central controller, based on real-time monitoring data of total nitrogen, total phosphorus, and chlorophyll a in the ecological control pond, the opening of the first adjustable weir gate, located between the filter-feeding biological pond and the large algae pond within the ecological control pond, is dynamically adjusted. Based on water temperature data at different heights within the aquaculture pond, the injection depth of the nozzles in the disinfection and recirculation unit is controlled. This method constructs a complete aquaculture water treatment methodology integrating biological domestication, circulating purification, and intelligent control. The independent functions of the aforementioned device units are integrated into an organically synergistic and sequentially acting complete process chain. This represents a leap from discrete equipment innovation to a replicable and scalable systematic solution, providing clear operational guidelines for closed-loop recirculating aquaculture of marine shrimp and crabs. Through the "dynamic control steps," the intelligent decisions of the central controller are transformed into real-time and precise adjustments to the hydraulic distribution in the ecological control pond and the injection depth of the disinfection and recirculation unit. This method not only maintains continuous water circulation but, more importantly, proactively optimizes the internal treatment paths and energy distribution based on real-time water quality and temperature feedback, thereby dynamically maintaining the aquaculture environment at its optimal state and significantly improving the predictability and accuracy of water quality management. After the biofilm in the biological filter matures, seedlings are introduced, ensuring that the treatment capacity of the purification system is activated and matched with the pollution load of aquaculture. At the same time, the dynamic control steps can respond to water quality fluctuations caused by different growth stages of shrimp and crabs and changes in the external environment, so that the system's operation strategy is always adapted to the actual needs of the farmed species, achieving water quality safety throughout the entire aquaculture process.

[0024] The water circulation and purification method for marine shrimp and crab farming ponds, specifically the stratified water temperature control step in the dynamic regulation process, includes: During the day or in hot seasons, when the surface water temperature of the aquaculture pond is detected to be significantly higher than that of the bottom layer, the nozzles are lowered to near the bottom layer to inject purified water from the bottom, thereby pushing the bottom water to rise and breaking up the thermal stratification. At night or when heat preservation is required, control the nozzle to be raised to near the water surface for injection, so as to reduce disturbance to the water temperature stratification structure and maintain the temperature of the bottom water.

[0025] Based on two diametrically opposed injection strategies for different time periods and seasons, this method demonstrates a high degree of targetedness and scientific rigor in its design. By controlling the injection of purified water from the bottom to push the bottom water level up, it can actively break up thermal stratification, effectively solving the problem of bottom hypoxia caused by stratification during high-temperature seasons. By injecting from the surface to reduce disturbance, it can consciously maintain a stratified structure conducive to heat preservation. This achieves a leap from "passive adaptation" to "active shaping" of the aquatic physical environment. This regulation method can intelligently select the most favorable aquatic structure pattern for farmed organisms according to diurnal rhythms and environmental needs. Breaking stratification during the day can prevent the formation of "oxygen debt" and the accumulation of toxic substances at the bottom; maintaining stratification at night helps to lock in the bottom water temperature and mitigate the stress caused by sudden temperature drops. This strategy, which follows natural laws and involves precise intervention, creates a more stable and less stressful habitat for shrimp and crabs, meeting the inherent requirements of ecological aquaculture. This method uses the return water as an energy carrier and power tool, and the changes in its injection depth directly achieve different hydrodynamic objectives. When breaking up stratification, the kinetic energy of the water body is used to promote vertical mixing, thus avoiding the energy consumption of additional aerators or mixing equipment; when maintaining stratification, energy conservation is achieved by reducing energy input. This allows the disinfection recirculation unit to perform its core disinfection function while also taking on multiple roles in intelligently regulating the physical structure of the water body, achieving functional integration and improved energy efficiency. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0027] Figure 1 This is a two-dimensional schematic diagram of the overall device of the present invention; Figure 2 This is a three-dimensional schematic diagram of the overall device of the present invention; Figure 3 This is a schematic diagram of the aquaculture pond of the present invention; Figure 4 This is a schematic diagram of the liftable water spray pipe and nozzle of the present invention; Figure 5 This is a schematic diagram of Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of Embodiment 3 of the present invention.

[0028] Attached diagram descriptions: 1-Aquaculture pond, 2-Filter dam, 3-Biological filter, 4-Ecological regulation pond, 5-Disinfection and reflux unit, 11-Inlet gate, 12-Outlet gate, 13-Filter screen, 1a-Shrimp and crab farming area, 1b-Sedimentation area, 14-Temperature sensor, 15-Liftable spray pipe, 15a-Sprinkler head, 31-Aeration hole, 41-Filter feeding biological pond, 42-Large algae pond, 43-First adjustable weir gate, 44-Water quality monitoring module, 45-Second adjustable weir gate, 51-Sealed storage tank, 51a-Immersion ultraviolet disinfection lamp assembly, 52-Reflux pipe, 52a-Pumping component No. 1, 53-Reflux branch pipe, 53a-Pumping component No. 2. Detailed Implementation

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

[0030] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Example 1: This system is applied to a marine shrimp and crab farming pond, aiming to achieve internal water circulation and self-purification, reducing the need for water exchange and pollution to the external environment. The main components of the system include aquaculture pond 1, filter dam 2, biological filter 3, ecological regulation pond 4, disinfection and reflux unit 5, and central controller. All components are connected by pipes and valves to form a closed loop.

[0032] See attached document Figure 1 , 2 As shown, the aquaculture pond 1 is a rectangular concrete structure with a bottom designed to slope from the inlet to the outlet at an angle of approximately 2% to facilitate the collection of solid waste towards the outlet. The side walls are equipped with an inlet gate 11 and an outlet gate 12, both electrically controlled. A filter screen 13 (2mm mesh size) is installed parallel to the surface of the pond, dividing the water into an upper shrimp and crab farming zone 1a and a lower sedimentation zone 1b. An array of temperature sensors 14 is also installed in the aquaculture pond 1, positioned at 0.2 meters below the surface, 0.8 meters in the middle layer, and 1.2 meters below the bottom layer, for real-time monitoring of water temperature stratification.

[0033] See attached document Figure 1 ,2 The filter dam 2 shown is located downstream of the outlet of aquaculture pond 1 and is a brick-built dam structure. Internally, it is divided into three series-connected filter chambers along the water flow direction: a coarse filter chamber, an adsorption chamber, and a buffer conditioning chamber. The coarse filter chamber is filled with 10-30mm diameter ceramsite to trap large suspended solids; the adsorption chamber is filled with 5-15mm diameter zeolite to adsorb ammonia nitrogen and heavy metals; and the buffer conditioning chamber is filled with 20-40mm diameter coral stone to stabilize pH and provide trace elements. The chambers are separated by perforated partitions with 5mm pores to prevent cross-contamination of filter media.

[0034] See attached document Figure 1 , 2 As shown, the bottom of the biological filter 3 is equipped with aeration holes 31. The biological filter 3 is connected to the outlet of the filter dam 2, and the aeration holes 31 are connected to external aeration equipment. The tank is filled with combined biological packing materials, including suspended ball packing materials (80mm in diameter) and elastic three-dimensional packing materials (specific surface area > 300 m²). 2 / m 3 This provides an attachment interface for nitrifying bacteria. A dissolved oxygen sensor is installed inside the tank to ensure that the dissolved oxygen concentration is maintained at 4-6 mg / L.

[0035] See attached document Figure 1 , 2 As shown, the ecological regulation pond 4 is an open-air earthen pond, divided into a filter-feeding biological pond 41 and a large algae pond 42, which are connected by a first adjustable weir gate 43. The filter-feeding biological pond 41 is equipped with multi-layered suspended culture racks for cultivating oyster strings (10-15 oysters per string); the large algae pond 42 is equipped with hydroponic algae floating boards for growing Asparagus setaceus. Water quality monitoring modules 44 are installed in both the filter-feeding biological pond 41 and the large algae pond 42 to monitor the concentrations of total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chl-a) in real time.

[0036] See attached document Figure 1 , 2 As shown in Figure 4, the disinfection return unit 5 includes a sealed storage tank 51 and a return pipe 52. A first pumping assembly 52a is installed in the return pipe 52 to transport water from the large algae pond 42 into the sealed storage tank. The sealed storage tank 51 is made of stainless steel and contains an immersion-type ultraviolet disinfection lamp assembly 51a (2kW power, 254nm wavelength). A return branch pipe 53 is led out from the water tank and connected to a rotatable spray head 15a. A second pumping assembly 53a is installed in the return branch pipe 53 to transport water from the sealed storage tank 51 into the liftable spray pipe 15.

[0037] The central controller employs a PLC control system and integrates a weather data receiving module (obtaining 24-hour forecasts of sunlight, temperature, and wind speed via the internet). The central controller connects to all sensors (water temperature, water quality, flow rate, etc.) and actuators (gates, weirs, lifting masts, regulating valves, etc.), and incorporates a built-in BP neural network model for optimizing control strategies.

[0038] Regarding system startup and normal operation, the inlet gate 11 is opened to fill the aquaculture pond 1 with seawater (salinity 30‰). Nitrifying and denitrifying bacteria are added to the biological filter 3 for biofilm formation and continuous aeration. The biofilm formation period is approximately 2-3 weeks. Once the biofilm has matured (indicated by an ammonia nitrogen removal rate >80%), shrimp and crab seedlings are introduced into the aquaculture pond 1. During the aquaculture period, the system continues to operate. When the sludge in the sedimentation zone 1b accumulates to a certain height, the outlet gate 12 is opened to allow water to flow from the aquaculture pond 1 into the filter dam 2. In the filter dam 2, the water undergoes cascade filtration to remove suspended solids and adsorbed pollutants; then it enters the biological filter 3 for biological nitrification, converting ammonia nitrogen into nitrates; subsequently, it flows into the ecological regulation pond 4, where nutrients are further removed through shellfish filter feeding and algae absorption; finally, after ultraviolet disinfection by the disinfection and return unit 5, it is returned to the aquaculture pond 1 through nozzle 15a.

[0039] Example 2: See attached document Figure 5 As shown, this embodiment is a specific implementation of the marine shrimp and crab aquaculture pond water circulation and purification system of Embodiment 1. It aims to explain in detail how the central controller executes the dynamic control algorithm of the hydraulic residence time of the ecological control pond 4 in order to maximize the water purification efficiency of the "shell-algae" subsystem.

[0040] See attached document Figure 1 , 2As shown, in the ecological control pond 4, the filter-feeding biological pond 41 and the large algae pond 42 are connected in series: the water flow path is as follows: water first enters the filter-feeding biological pond 41, then enters the large algae pond 42 through the first adjustable weir 43, and then flows out of the ecological control pond 4 through the second adjustable weir 45. An online total suspended particulate matter (TSS) sensor is installed at the inlet of the filter-feeding biological pond 41, and an online total nitrogen (TN) sensor is installed at the outlet of the large algae pond 42. A water temperature sensor is also installed inside the pond. All these sensors are connected to the central controller. Both the first adjustable weir 43 and the second adjustable weir 45 are electrically adjustable weirs, and their opening (0%-100%) is precisely controlled by an actuator driven by the central controller. The opening of the first adjustable weir 43 regulates the flow rate from the filter-feeding biological pond 41 to the large algae pond 42; the opening of the second adjustable weir 45 controls the flow rate from the large algae pond 42 to the disinfection and return unit 5. By independently adjusting the opening of the two weirs, the hydraulic retention time (HRT) of the filter-feeding biological pond 41 and the large algae pond 42 can be controlled separately. A trained BP neural network model is pre-installed in the central controller, and a control program incorporating the aforementioned dynamic regulation algorithm has been written. To ensure the BP neural network model possesses good generalization ability and prediction accuracy, it needs to be fully trained before the system is put into use. The model's training dataset is constructed primarily through two methods: first, historical operational data collection. In the prototype system or a similar experimental base, after at least one complete aquaculture cycle (e.g., 90-120 days from stocking to harvest), key water quality parameters (such as TSS, TN, and water temperature), corresponding weir opening combinations (K1, K2), and the final system purification efficiency data are systematically collected under different seasons and aquaculture stages. This data constitutes the main body of the training dataset, ensuring that the model learns complex nonlinear relationships under real-world conditions. Given that historical data may not cover all extreme or boundary conditions, we established a mechanistic model of the ecological regulation pond based on the principles of water purification kinetics and aquaculture technology knowledge. This model generates a large amount of simulated data covering various potential operating conditions, supplementing and expanding the historical dataset to improve the model's robustness and ability to handle abnormal situations. Finally, the data from the two sources are cleaned, normalized, and validated, then merged to form a complete training dataset. Using this dataset, the BP neural network is subjected to offline supervised learning via the backpropagation algorithm until the error between the model's output value and the expected output value reaches the preset accuracy requirement. The trained model parameters (weights and thresholds) are then fixed and embedded into the central controller's program for online real-time decision-making.

[0041] The central controller executes the following algorithm once at a fixed time period (e.g., every 30 minutes) to determine the optimal opening of the first adjustable weir gate 43 and the second adjustable weir gate 45.

[0042] S1: Data Acquisition and Preprocessing The central controller acquires real-time data from sensors, TSS 实时 =Total suspended particulate matter concentration at the inlet of filter-feeding biological tank 41 (unit: mg / L), TN 实时 =Total nitrogen concentration at outlet 42 of large algae pond (unit: mg / L), T 实时 =Water temperature in ecological control pond 4 (unit: °C). To prevent interference from instantaneous data fluctuations, the central controller will take the moving average of the most recent 5 sampled values ​​as the input value for this calculation.

[0043] S2: Determination of Objective Function and Weighting Factors The algorithm constructs a bi-objective optimization function with the system's total nitrogen removal rate and total suspended solids removal rate as its core. Its key lies in introducing a weighting factor that adapts to the shrimp and crab's growth stage. The weighting factor (α) is defined as follows: this factor is used to balance the priority of TN removal and TSS removal.

[0044] In the early stages of aquaculture (0-30 days after stocking), shrimp and crab larvae are small, have low metabolism, require less feed, and have minimal water pollution. The key to management is maintaining water cleanliness and preventing excessive particulate matter from affecting larvae survival rates. Therefore, the weighting is biased towards TSS removal, with α=0.3 (i.e., TN weighting is 0.3, and TSS weighting is 0.7).

[0045] During the mid-stage of aquaculture (31-60 days), biological growth accelerates, feeding increases, and dissolved pollutants such as ammonia nitrogen begin to accumulate. At this time, a balancing treatment is required, with α set at 0.5.

[0046] Late-stage aquaculture (61 days to harvest): The cultured organisms reach maximum biomass, feeding rates peak, and the system's nitrogen and phosphorus load is at its heaviest. The focus of regulation is preventing excessive levels of ammonia nitrogen and nitrite. Therefore, the weighting is biased towards TN removal, with α set to 0.7. The central controller has an internal timing program that automatically switches the value of the weighting factor α according to a preset aquaculture calendar.

[0047] Weighted overall purification efficiency = α × total nitrogen removal rate + (1-α) × total suspended solids removal rate.

[0048] S3: Reasoning and Decision Making in Backpropagation Neural Network Models Preprocessed TSS 实时， TN 实时 T 实时 The four parameters, including the weight factor α corresponding to the current breeding stage, are normalized and mapped to the [0,1] interval, and then used as input vectors to be fed into the pre-trained BP neural network model.

[0049] The neural network model structure has an input layer with 4 nodes, corresponding to the 4 input parameters mentioned above. The hidden layer can be designed as 1 or 2 layers, with 6-10 nodes per layer. This embodiment uses a single hidden layer with 8 nodes, employing the Tanh activation function. The output layer has 2 nodes, using the Sigmoid activation function. The output values ​​are the optimal opening K1 of the first adjustable weir gate 43 and the optimal opening K2 of the second adjustable weir gate 43, i.e., (0%≤K1≤100%, 0%≤K1≤100%). The neural network optimizes by maximizing the weighted comprehensive purification efficiency defined in S2, and calculates the optimal opening combination K1 and K2 under the current water quality and aquaculture stage through internal nonlinear mapping. Before the system is put into use, this BP neural network is trained using a sample set consisting of orthogonal experimental calibration data and ecological hydrodynamic simulation data. Offline supervised training is performed using the Levenberg-Marquardt improved error backpropagation algorithm, with mean squared error as the loss function. When the training iteration error is reduced to 1×10⁻⁶, the optimal combination is determined. -3 The training is then completed, and the final connection weights and thresholds are stored in the central controller to ensure the speed and reliability of online decision-making. After obtaining the output results of K1 and K2, the central controller directly drives the corresponding actuators to adjust the first adjustable weir gate 43 and the second adjustable weir gate 45 to the target opening.

[0050] Suppose that in the afternoon during the middle of aquaculture, the system's operating data is as follows: Real-time data: TSS 实时 =25mg / L,TN 实时 =1.8mg / L,T 实时 =28℃.

[0051] The breeding stage is day 45, so the weighting factor α = 0.5.

[0052] The central controller inputs the data set [TSS=25, TN=1.8, T=28, α=0.5] into the trained BP neural network. After forward propagation calculations within the neural network, the final output layer yields the results: K1=40%, K2=60%.

[0053] In this situation, the system determines that the current suspended particulate matter load is high, so it appropriately restricts the flow rate into the large algae pond (K1=40%), while allowing a larger flow rate out (K2=60%), in order to extend the HRT of the filter-feeding biological pond and enhance the filter feeding effect of shellfish; at the same time, it moderately controls the HRT of the large algae pond to balance algae absorption and the overall hydraulic load of the system.

[0054] Example 3: See attached document Figure 4 , 6As shown, this embodiment is a specific implementation of the aforementioned marine shrimp and crab aquaculture pond water circulation and purification system. It aims to explain in detail how the central controller, based on real-time water temperature and weather forecast data, controls the injection depth of the nozzles 15a in the disinfection return unit 5 to achieve intelligent temperature stratification control of the aquaculture pond 1. The core of this embodiment lies in the system's ability to identify and utilize the dynamic conditions created by the temperature difference between the return water and the pond water to achieve distinctly different control objectives.

[0055] See attached document Figure 3 As shown, a temperature sensor array 14 is arranged vertically in the aquaculture pond 1. It typically includes at least three sensors, each fixed to the surface (0.2 meters above the water surface) to measure the surface water temperature T. s The water temperature T in the middle layer (the center of the water depth, about 0.75 meters) m The water temperature T at the bottom (approximately 1.2 meters from the bottom of the pool) is... b .

[0056] See attached document Figure 4 As shown, each nozzle 15a is connected to a liftable water pipe 15, whose raising and lowering can be precisely controlled by a central controller, thereby changing the depth (H1) of the injected water. The central controller is connected to a weather data receiving module, which can acquire weather forecast data for the next 24-48 hours, including: future temperature (T). a ), light intensity (I) f ) and wind speed (W f ).

[0057] The water in the disinfection reflux unit 5 exchanges heat with the external environment as it flows through the entire system, and its reflux temperature (T) h The reflux temperature T is dynamically changing. h The primary heat source is solar energy generated as the water flows through the open-air ecological regulation pond 4. The main cooling effect of the system originates from the continuous heat dissipation achieved through surface evaporation, convection heat transfer, and thermal radiation as the water flows through the filter dam 2, biological filter 3, and ecological regulation pond 4. Therefore, T h Typically, the temperature is closer to the ambient temperature at the time of the event. However, in aquaculture ponds, especially deep water, temperature changes lag due to greater thermal inertia, resulting in stratification. The key to intelligent system control lies in... h Whether the pool water is cold or hot, the temperature difference can be converted into the power to achieve the control target by controlling the injection depth.

[0058] The central controller executes the core algorithm described below once at fixed time intervals (e.g., every 15 minutes) and triggers additional calculations in a feedforward mode when significant weather changes are predicted.

[0059] S1: Real-time thermal stratification intensity calculation The central controller reads data from the temperature sensor array and calculates two key metrics: ΔT=T s -T b ΔT is the temperature difference between the surface and the bottom layer, which is the most direct indicator for determining the existence and intensity of thermal stratification.

[0060] Temperature gradient, where G s =(T s -T m) / (H m -H s ), where G s For the surface-to-middle layer gradient, T s For surface temperature, T m For the middle layer temperature, T s -T m The calculation refers to the total temperature difference between the surface and middle layers; H m For mid-level height, H s Surface height H m -H s It calculates the total depth difference between the surface and the middle layers; the result of this formula is how many degrees Celsius the temperature drops per meter of water depth within the "surface to middle layer" interval.

[0061] G b =(T m -T b ) / (H b -H m ), where G b For the middle-to-lower-layer gradient, T b For the bottom layer temperature, H b The bottom layer is the water depth. Similarly, the calculation is for the temperature change per meter of water depth within the "middle layer to bottom layer" range.

[0062] M G =max(|G s |,|G b |), where M G To find the maximum gradient, compare the absolute values ​​of the gradients in the two intervals above, and take the maximum value, M. G This represents the intensity of the water layer in the entire body where the temperature changes most drastically (i.e., the thermocline).

[0063] Reflux temperature difference ΔT i The central controller calculates the temperature difference between the return water and different layers of water in the aquaculture pond. Temperature difference ΔT between reflux water and bottom water hb =T h -T b , Temperature difference ΔT between return water and surface water hs =Th -T s , The sign and magnitude of these two data points directly determine the buoyancy effect after injection into the water body, and are important bases for selecting control strategies and evaluating effects.

[0064] S2: Regulation Strategy Selection and Feedforward Triggering The central controller compares the calculated ΔT with a preset activation threshold. This threshold can be set based on the sensitivity of the farmed species, establishing a stratification breaking threshold ΔT. b and maintain the stratification threshold ΔT m When ΔT ≥ ΔT b (A typical scenario is a summer afternoon), water in nozzle 15a is injected from the bottom layer, at which time T is usually... h >T b (i.e., ΔT) hb >0), the return water is "warm light water". After being injected from the bottom of aquaculture pond 1, its low density generates strong buoyancy, drawing in and pushing the surrounding cold bottom water upwards, creating strong vertical mixing and efficiently breaking up stratification. When ΔT≤ΔT m (Typical scenario: nighttime, cloudy day) Water in nozzle 15a is injected from the surface to reduce disturbance to the water body. At this time, T... h ≤T s (i.e., ΔT) hs When the lower-temperature, higher-density return water (≤0) is injected from the surface, its density, being higher than the warmer surface water below, immediately forms a stable, downward-spreading density flow. This flow, under the influence of gravity, slowly infiltrates in a laminar manner, greatly suppressing turbulence and vertical convection caused by wind and water inertia. This "laminar coverage" effect effectively isolates the warmer bottom water from the cold atmosphere, significantly slowing down heat exchange (especially heat loss) between the water and air, providing a stable growth environment for shrimp and crabs, and reducing the energy consumption for maintaining the system's temperature. When ΔT m <ΔT<ΔT b The height of nozzle 15a remains unchanged, and the system is in a stable transition state, requiring no adjustment.

[0065] S3: Feedforward Prediction and Control (Based on Weather Forecast) This is the optimization part of the algorithm, enabling the system to have predictive capabilities. The central controller analyzes the received weather forecast data. The central controller calculates the future heat gain index (F). u ), F u =w1×(I fm / I rm )+w2×(T p -T ac ), where I fm For the predicted maximum illumination, Irm For reference light intensity, T p T is the predicted peak temperature. ac Here, w1 represents the current air temperature, and w2 represents the weighting coefficients. The core purpose of this formula is to quantify and predict the extent of heating effect that the external environment will have on the aquaculture pond water over a future period (e.g., the next 6-24 hours).

[0066] When strong heating is predicted, F u If the set threshold is exceeded, even if the current ΔT has not yet been reached. b The central controller can also set the nozzle 15a depth to the bottom height H in advance, either on the night of the same day or the following morning. b By utilizing the power of the returning water (regardless of its temperature), the thermal stability of the water body is weakened in advance. This means that during the daytime heating process, more solar energy is required to re-establish strong stratification, thus delaying or mitigating the formation of harmful stratification and preventing problems before they occur.

[0067] When strong cooling is predicted, the central controller can pre-set the nozzle depth to H. s This may reduce the backflow rate. Purpose and principle: To maximize the protective effect of surface injection on the bottom insulation layer, slow down the rate of temperature drop in the bottom water, and provide a buffer for aquaculture organisms to cope with sudden temperature drops.

[0068] Based on the decision results of S2 and S3, the central controller outputs the final control command to determine the target depth H. t By combining real-time and feedforward decision-making, the final target depth of nozzle 15a is determined. The central controller sends a command to the liftable water hose 15 to adjust it to H. t Depth. In the next cycle after the adjustment execution, the central controller recalculates ΔT and M. G The central controller can then assess the effectiveness of the control measures. If the results are not as expected, the central controller can fine-tune the nozzle depth (e.g., precisely position the nozzle at the bottom of the identified thermocline) or adjust the return flow rate accordingly to optimize mixing or insulation efficiency.

[0069] The following example uses a specific calculation to illustrate the real-time data T during a sunny summer day. s =31.0℃,T b =26.5℃, calculate ΔT=4.5℃. T h =30.5℃ to obtain ΔT hb =+4.0℃. The weather forecast predicts sunny and hot weather the next day, F u The index is relatively high. High F uThe index indicates extremely strong solar energy input the following day, which will drive the water body to absorb a large amount of heat, thus drastically exacerbating water temperature stratification (ΔT will be much greater than today). This stronger stratification will lead to more severe bottom-level anoxic conditions. To counteract this process in advance, the system chooses to act ahead of time during the night when the thermal stratification is weakest. The purpose of implementing the "breaking stratification" strategy in advance at night is not to solve the current anoxic conditions, but to preemptively deplete the water body's "thermal stability" or "thermal inertia" through gentle mixing throughout the night.

[0070] The system implemented a "break-the-stratification" strategy in advance at night, placing the nozzles at the bottom layer for gentle mixing throughout the night, thus preemptively weakening the water's stability. The system detected that ΔT = 4.5℃ was significantly exceeded, and ΔT... hb =+4.0℃ (the return water is significantly warm). Therefore, the bottom injection strategy was maintained and strengthened. Warm return water (30.5℃) was injected from the bottom of the pool. Because its temperature was much higher than the bottom water temperature (26.5℃), it generated extremely strong buoyancy, forming an upwelling that powerfully agitated the water, achieving efficient mixing. Forced vertical circulation directly transported the oxygen-rich surface water to the bottom, while simultaneously pushing the oxygen-deficient bottom water to the surface for contact with air. After the thermal stratification was broken, the stable "oxygen debt zone" previously formed at the bottom due to oxygen isolation was completely destroyed, preventing the reproduction of anaerobic microorganisms and the production of toxic substances such as hydrogen sulfide. Two hours later, T b The temperature rose to 28.0℃, and ΔT dropped to 4.0℃, significantly increasing dissolved oxygen at the bottom layer and effectively mitigating the risk of hypoxia. By integrating the temperature characteristics of the return water into the control logic, this embodiment clearly demonstrates how the system can go beyond simple temperature judgment and instead utilize the principles of water physics and dynamics to achieve more scientific, energy-efficient, and precise intelligent environmental management.

[0071] This embodiment clearly demonstrates how the circulating purification system transcends traditional fixed-mode operation. Through a complex, adaptive intelligent algorithm, it dynamically optimizes the working state of the ecological purification unit, thereby maintaining excellent water quality stably and efficiently throughout the entire aquaculture cycle.

[0072] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art can make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as the technology or embodiments that are substantially the same as the present invention.

[0073] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A water circulation and purification system for marine shrimp and crab farming ponds, characterized in that, include: Aquaculture pond (1) is used for raising shrimp and crabs; The filter dam (2) has its inlet connected to the drain outlet of the aquaculture pond (1), and the filter dam (2) is filled with one or more filter media selected from zeolite, coral stone or ceramsite. The biofilter (3) has its inlet connected to the outlet of the filter dam (2) and is filled with biological packing material for attaching microorganisms. An ecological regulation pond (4) is connected to the outlet of the biological filter pond (3) at its inlet. The ecological regulation pond (4) is divided into a filter-feeding biological pond (41) and a large algae pond (42). Oysters or mussels are suspended in the filter-feeding biological pond (41), and seaweed or purslane are planted in the large algae pond (42). The filter-feeding biological pond (41) and the large algae pond (42) are connected by a first adjustable weir gate (43). The disinfection return unit (5) has its inlet connected to the outlet of the ecological regulation pool (4), and its outlet returns to the aquaculture pool (1) through a pipeline, forming a circulation loop; And a central controller, which connects to multiple actuators and sensor signals within the system.

2. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 1, characterized in that, The aquaculture pond (1) has an inlet gate (11) and an outlet gate (12) on its side wall. The bottom height gradually decreases from the inlet gate (11) to the outlet gate (12). The aquaculture pond (1) is equipped with a filter screen (13). Above the filter screen (13) is the shrimp and crab aquaculture area (1a), and below it is the sedimentation area (1b).

3. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 1, characterized in that, Water quality monitoring modules (44) are installed in the filter-feeding biological pool (41) and the large algae pool (42) to monitor the total nitrogen, total phosphorus and chlorophyll a content in the water in real time; the disinfection return unit (5) includes a return pipe (52) and a second adjustable weir (45) is provided between the return pipe (52) and the large algae pool (42); the water quality monitoring module (44) is connected to the central controller, and the central controller can dynamically adjust the opening of the first adjustable weir (43) and the second adjustable weir (45) according to the water quality data to control the hydraulic residence time of the water in the filter-feeding biological pool (41) and the large algae pool (42).

4. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 3, characterized in that, The central controller is configured to execute a dynamic allocation algorithm for the hydraulic retention time of an ecological control pond (4), the steps of which are as follows: S1: Obtain water quality parameters representing suspended solids and nutrient load inside the ecological regulation pond (4) through the water quality monitoring module; S2: The optimization target is the synergistic removal efficiency of the system for suspended solids and nutrients, and the focus of the target can be dynamically adjusted according to the breeding stage; S3: Input the acquired water quality parameters into a neural network model, which outputs the optimal hydraulic retention time allocation instruction corresponding to the current water quality condition; S4: The central controller automatically adjusts the opening of the first adjustable weir gate (43) and the second adjustable weir gate (45) set in the ecological control pool (4) according to the instructions.

5. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 3, characterized in that: The disinfection return unit (5) includes a sealed storage tank (51), a return pipe (52) is provided between the sealed storage tank (51) and the large algae pond (42), a return branch pipe (53) is provided between the sealed storage tank (51) and the aquaculture pond (1), and an immersion ultraviolet disinfection lamp group (51a) is provided in the sealed storage tank (51); a number of liftable water spray pipes (15) are arranged at the bottom of the aquaculture pond (1), and the water in the sealed storage tank (51) is transported to each liftable water spray pipe (15) through the return branch pipe (53).

6. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 5, characterized in that: The liftable water spray pipe (15) passes through the bottom of the breeding pond (1) and the filter screen (13), and the outlet of each liftable water spray pipe (15) is a nozzle (15a) with adjustable direction.

7. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 5, characterized in that, The aquaculture pond (1) is equipped with an array of temperature sensors (14) at different heights. The array of temperature sensors (14) is connected to the central controller. Based on the data fed back by the array of temperature sensors (14), the lifting and lowering of the water spray pipe (15) is controlled, thereby precisely adjusting the injection depth of the nozzle (15a) to achieve stratified regulation of the water temperature in the aquaculture pond (1) or to break the water stratification.

8. The marine shrimp and crab aquaculture pond water circulation and purification system according to claim 6, characterized in that, The central controller is also connected to a weather data receiving module and is configured to predict the water temperature stratification trend of the aquaculture pond (1) based on the received future light, temperature and wind speed forecast data, combined with the real-time data of the temperature sensor (14) array, and control the water injection depth of the nozzle (15a) in advance to regulate the temperature stratification structure of the aquaculture water.

9. A method for utilizing the marine shrimp and crab aquaculture pond water circulation and purification system based on claim 8, characterized in that, Includes the following steps, System startup steps: Fill the aquaculture pond (1) with seawater; add nitrifying and denitrifying bacteria agents to the biological filter (3) for biofilm culture; Normal operation steps: After the biofilm in the biological filter (3) matures, shrimp and crab seedlings are introduced for breeding. The system continues to operate, and the water flows through the filter dam (2), biological filter (3), ecological regulation pond (4) and disinfection return unit (5) in sequence before returning to the breeding pond (1). Dynamic control steps: The opening of the first adjustable weir gate (43) between the filter-feeding biological pool (41) and the large algae pool (42) in the ecological control pool (4) is dynamically adjusted by the central controller based on the real-time monitoring data of total nitrogen, total phosphorus and chlorophyll a in the ecological control pool (4); the injection depth of the nozzle (15a) in the disinfection return unit (5) is controlled based on the water temperature data at different heights in the aquaculture pool (1).

10. The method for circulating and purifying water in marine shrimp and crab aquaculture ponds according to claim 9, characterized in that, The water temperature stratification control in the dynamic control step specifically includes: During the daytime or high-temperature season, when the surface water temperature of the aquaculture pond (1) is detected to be significantly higher than that of the bottom layer, the nozzle (15a) is controlled to descend to near the bottom layer, and purified water is injected from the bottom to push the bottom water to rise and break the thermal stratification. At night or when heat preservation is required, the nozzle (15a) is raised to near the water surface for injection to reduce disturbance to the water temperature stratification structure and maintain the bottom water temperature.

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