An aquaculture pond cleaning period tail water grading treatment method based on carbon source precise regulation and process optimization

Abstract

The present application relates to a kind of water classification treatment method of water tail during pond cleaning period based on carbon source precision control and process optimization in aquaculture, comprising the following: first, after pond cleaning, standing drainage, retaining rich water body;Then activate the mud and based on innovative carbon source dosing model accurately input high C / N ratio solid carbon source;Subsequently, in-situ enhanced denitrification under the control logic of dynamic dissolved oxygen;Finally, the treated water is discharged into the tail water treatment area of biological reinforcement for deep purification.The water classification treatment method of water tail during pond cleaning period based on carbon source precision control and process optimization proposed in the present application makes full use of existing pond to carry out the most expensive high-load pretreatment, without additional occupation of a large amount of land to build pretreatment facilities, the construction and operation cost is greatly reduced.The in-situ denitrification efficiency is high, which reduces the pressure of the back-end treatment.The agricultural waste such as bagasse powder is used as carbon source, which realizes the resource utilization of waste.The whole process is mainly biological treatment, without secondary pollution risk of chemical agents.

Description

Technical Field

[0001] This invention relates to the technical fields of aquaculture and environmental protection, and in particular to a method for graded treatment of tailwater during the pond clearing period of aquaculture based on precise carbon source control and process optimization. Background Technology

[0002] Aquaculture wastewater, especially the wastewater discharged during the pond clearing period, contains high concentrations of pollutants such as nitrogen, phosphorus, and organic particulate matter, and is one of the main sources of pollution leading to eutrophication of surrounding waters.

[0003] Currently, mainstream wastewater treatment technologies such as the "three pools and two dams" (sedimentation tank, aeration tank, ecological tank, and two filtration dams) have certain effects, but they have significant shortcomings: 1) Insufficient applicability: Traditional processes have limited capacity to handle the high-load wastewater impact generated during the pond clearing period, easily leading to treatment failure; 2) Large land area: Additional treatment facilities are required, resulting in high land costs; 3) Low carbon source utilization efficiency: Inadequate carbon source supplementation during denitrification often leads to insufficient carbon sources resulting in incomplete denitrification, or excessive carbon sources causing secondary pollution and cost waste. Furthermore, the conventional method involves setting a fixed threshold for dissolved oxygen (DO) in the corresponding water body and determining whether to shut down the aeration equipment based on the relationship between the current DO and the fixed threshold. However, this method has the following problems: rising water temperature leads to a decrease in dissolved oxygen saturation, resulting in a more severe actual oxygen deficiency for the same DO value; increased organic matter content increases oxygen consumption, requiring a higher control threshold to maintain the oxygen deficiency state; and natural oxygen deficiency at night or in the early morning leads to complete anaerobic blackening and bottom decay at the fixed threshold; 4) The pond's capacity was not fully utilized: After the pond was cleared, it was left idle, and its huge volume and treatment potential were not effectively utilized.

[0004] In production practice, after pond fish are harvested, the ponds need to undergo steps such as drainage, pond cleaning, pond drying, and disinfection before entering the next round of production. For major species such as California bass, sea bass, and tilapia, harvesting begins in November each year, and the ponds do not resume production until April of the following year, leaving them idle for nearly five months. Currently, the "three ponds and two dams" tailwater treatment technology mainly relies on sedimentation to remove total nitrogen from the water, with a total nitrogen removal efficiency of less than 40%. However, this technology cannot handle the concentrated tailwater discharge during the pond cleaning period after fish harvesting, becoming a major flaw in aquaculture tailwater treatment technology. The latest technologies in the industry, besides continuously increasing the pretreatment area (e.g., "four ponds and three dams" and "five ponds and four dams" derived from the "three ponds and two dams" system), only increase the tailwater treatment area, occupying 10-15% of land resources, and have limited effectiveness, resulting in the solidification and waste of land resources. If we can combine production realities and utilize idle ponds after pond clearing for wastewater pretreatment, we can solve the problem of peak wastewater pollution during the pond clearing period. Theoretically, the pretreatment area can be increased to 100%, meaning that all existing aquaculture ponds can be used for aquaculture wastewater pretreatment, and almost no additional land resources or costs are required. Summary of the Invention

[0005] The purpose of this invention is to at least address one of the shortcomings of the existing technology by utilizing idle ponds after aquaculture pond clearing, combining them with actual production after pond clearing, reducing unnecessary pond drying and disinfection time, and performing pretreatment processes such as solid sedimentation, aerobic nitrification, and anaerobic denitrification on the original ponds, thereby providing a graded treatment method for aquaculture pond clearing tailwater based on precise carbon source control and process optimization.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Specifically, a graded treatment method for aquaculture pond clearing wastewater based on precise carbon source regulation and process optimization is proposed, including the following: Step 110: After the aquatic products are harvested, the water in the original aquaculture pond is left to stand still for N days to achieve in-situ sedimentation. Then, the supernatant is discharged and enters the conventional tailwater treatment process, leaving a rich water body of depth H at the bottom of the pond. Step 120: Mechanically disturb the bottom sediment in the enriched water body to fully mix the bottom sediment with the water body to form a homogenized mud-water mixture. Based on the pond area and the estimated initial total nitrogen concentration in the mud-water mixture according to the preset rules, add a carbon source with a preset carbon-nitrogen ratio of M to the current pond. Step 130: After adding the carbon source, turn on the pond aerator for 3-5 days to maintain the dissolved oxygen in the mud-water mixture at no less than 3 mg / L for aerobic biological denitrification. Then turn off the aerator and maintain the pond water in an anoxic-anaerobic state for in-situ anaerobic biological denitrification treatment for a period of T days (T≥10 days). When the total nitrogen in the effluent drops below 10 mg / L, proceed to the next treatment step. Utilizing the cleaned pond for in-situ treatment improves land use efficiency and reduces the area required for subsequent effluent treatment. Step 140: Discharge the water body after the denitrification treatment to the tailwater treatment area for treatment until the total nitrogen, total phosphorus, COD, pH and suspended solids content in the water body reaches the preset discharge standards.

[0007] Furthermore, specifically, the value of N ranges from 3 to 5 days, and the value of H ranges from 0.4 to 0.6 meters.

[0008] Furthermore, specifically, the carbon source is at least one of sugarcane bagasse powder, straw powder, or cassava bagasse powder, with a particle size of 20-60 mesh and a carbon-to-nitrogen ratio (C / N) of 10-15:1.

[0009] Furthermore, specifically, the process of maintaining the pond water in a hypoxic-anaerobic state includes, A preset monitoring cycle is set, and M dissolved oxygen (DO) data are collected in the water body in each monitoring cycle. A floating DO threshold is set for each monitoring cycle based on the DO data within the monitoring cycle. Furthermore, for any monitoring period, the number of data points with DO values ​​lower than the corresponding floating DO threshold is recorded as M1. If M1 is lower than M_Th, it is determined that there is no hypoxia in the current monitoring period, and the oxygenation equipment is turned off in the next monitoring period. If M1 is not lower than M_Th, it is determined that there is hypoxia in the current monitoring period, and the oxygenation equipment is turned on in the next monitoring period, where M_Th is a preset quantity threshold.

[0010] Furthermore, specifically, a floating DO threshold is set for each monitoring period based on the DO data within that period, including: Let any monitoring period be [DO_1, DO_2, ..., DO_M], and DO_i, i∈[1,M]; The minimum value of DO_i is calculated as follows: ; Where avg· means to calculate the average value, max· means to calculate the maximum value, and min· means to calculate the minimum value; Then, the number of data corresponding to the small value farth coefficient being less than the preset coefficient threshold in the current monitoring period is counted as R1, and R1 / M is further calculated. The upward floating coefficient α of DO_Th is determined according to the interval where R1 / M is located. Then, (1+α)DO_Th is used as the floating DO threshold of the current monitoring period, where DO_Th is the preset benchmark value of DO threshold. By pre-dividing [0,1] into multiple intervals, each interval corresponds to an upward floating coefficient α. The upward floating coefficient α can be read according to the interval where R1 / M is located.

[0011] Furthermore, specifically, the tailwater treatment area is a "three pools and two dams" system, an artificial wetland, or a moving bed biofilm reactor (MBBR). The tailwater treatment area is filled with functional biological packing material, which is loaded with highly efficient nitrogen and phosphorus removal bacteria.

[0012] Furthermore, specifically, the highly efficient nitrogen and phosphorus removal agent is constructed based on a complex microbial community of Pseudomonas, Acinetobacter, and denitrifying bacteria.

[0013] Furthermore, specifically, the method for calculating the amount M of the fixed carbon source is as follows: ; Where A is the pond area and ρ is the empirical density coefficient. To preset the carbon-nitrogen ratio, For the estimated initial total nitrogen concentration, This is the theoretical nitrogen conversion efficiency coefficient of the carbon source.

[0014] The beneficial effects of this invention are as follows: This invention proposes a method and device for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization. On one hand, it fully utilizes existing ponds for the most expensive high-load pretreatment, eliminating the need for large-scale land acquisition for new pretreatment facilities, thus significantly reducing construction and operating costs. In-situ denitrification efficiency is high, alleviating pressure on downstream treatment. Using agricultural waste such as sugarcane bagasse powder as a carbon source achieves waste resource utilization. The entire process is primarily biological treatment, eliminating the risk of secondary pollution from chemical agents. On the other hand, while maintaining the pond water in an anoxic-anaerobic state, a floating DO threshold is set for each monitoring period based on DO data. This allows for intelligent control of aeration equipment, avoiding frequent start-ups and shutdowns, and dynamically adjusting the DO threshold. Compared to fixed thresholds, this method balances environmental factors and maintains the anoxic-anaerobic state more accurately. Attached Figure Description

[0015] The above and other features of this disclosure will become more apparent from the detailed description of the embodiments illustrated in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals denote the same or similar elements. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort. In the drawings: Figure 1 The diagram shows a flowchart of a method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to the present invention. Figure 2 The diagram shows the principle of a method for graded treatment of aquaculture tailwater during pond clearing based on precise carbon source regulation and process optimization according to the present invention. Detailed Implementation

[0016] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The same reference numerals used throughout the accompanying drawings indicate the same or similar parts.

[0017] Example 1, referring to Figure 1 as well as Figure 2 This invention proposes a method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization, comprising the following: Step 110: After the aquatic products are harvested, the water in the original aquaculture pond is left to stand still for N days to achieve in-situ sedimentation. Then, the supernatant is discharged and enters the conventional tailwater treatment process, leaving a rich water body of depth H at the bottom of the pond. Step 120: Mechanically disturb the bottom sediment in the enriched water body to fully mix the bottom sediment with the water body to form a homogenized mud-water mixture. Based on the pond area and the estimated initial total nitrogen concentration in the mud-water mixture according to the preset rules, add a carbon source with a preset carbon-nitrogen ratio of M to the current pond. Step 130: After adding the fixed carbon source, turn on the pond aerator for 3-5 days to maintain the dissolved oxygen in the mud-water mixture at no less than 3 mg / L for aerobic biological denitrification. Then turn off the aerator and maintain the pond water in an anoxic-anaerobic state for in-situ anaerobic biological denitrification treatment for a period of T days (T≥10 days). When the total nitrogen in the effluent drops below 10 mg / L, proceed to the next treatment step. Utilizing the cleaned pond for in-situ treatment improves land use efficiency and reduces the area required for subsequent effluent treatment. Step 140: Discharge the water body after the denitrification treatment to the tailwater treatment area for treatment until the total nitrogen, total phosphorus, COD, pH and suspended solids content in the water body reaches the preset discharge standards.

[0018] In this Example 1, existing ponds are fully utilized for the most expensive high-load pretreatment, eliminating the need for constructing new pretreatment facilities with large land areas, thus significantly reducing construction and operating costs. In-situ denitrification is highly efficient, alleviating pressure on downstream processing. Agricultural waste such as sugarcane bagasse powder is used as a carbon source, achieving waste resource utilization. The entire process is primarily biological treatment, eliminating the risk of secondary pollution from chemical agents.

[0019] In a preferred embodiment of the present invention, specifically, the value of N ranges from 3 to 5 days, and the value of H ranges from 0.4 to 0.6 meters.

[0020] In this preferred embodiment, the value of N is controlled within the range of 3-5 days, and the value of H is controlled within the range of 0.4-0.6 meters, which can better achieve the clearing and settling of the pond and the formation of the enriched water layer.

[0021] In a preferred embodiment of the present invention, the fixed carbon source is at least one of sugarcane bagasse powder, straw powder or cassava bagasse powder, with a particle size of 20-60 mesh and a carbon-nitrogen ratio (C / N) of 10-15:1.

[0022] In this preferred embodiment, agricultural waste such as sugarcane bagasse powder is used as a carbon source, realizing the resource utilization of waste. The entire process is mainly biological treatment, eliminating the risk of secondary pollution from chemical agents.

[0023] In this preferred embodiment, mechanical disturbance in the above manner can better achieve sediment activation.

[0024] In a preferred embodiment of the present invention, the process of maintaining the pond water in an anoxic-anaerobic state specifically includes: A preset monitoring cycle is set, and M dissolved oxygen (DO) data are collected in the water body in each monitoring cycle. A floating DO threshold is set for each monitoring cycle based on the DO data within the monitoring cycle. Furthermore, for any monitoring period, the number of data points with DO values ​​lower than the corresponding floating DO threshold is recorded as M1. If M1 is lower than M_Th, it is determined that there is no hypoxia in the current monitoring period, and the oxygenation equipment is turned off in the next monitoring period. If M1 is not lower than M_Th, it is determined that there is hypoxia in the current monitoring period, and the oxygenation equipment is turned on in the next monitoring period, where M_Th is a preset quantity threshold.

[0025] In a preferred embodiment of the present invention, specifically, a floating DO threshold is set for each monitoring period based on the DO data within the monitoring period, including... Let any monitoring period be [DO_1, DO_2, ..., DO_M], and DO_i, i∈[1,M]; The minimum value of DO_i is calculated as follows: ; Where avg· means to calculate the average value, max· means to calculate the maximum value, and min· means to calculate the minimum value; Then, the number of data corresponding to the small value farth coefficient being less than the preset coefficient threshold in the current monitoring period is counted as R1, and R1 / M is further calculated. The upward floating coefficient α of DO_Th is determined according to the interval where R1 / M is located. Then, (1+α)DO_Th is used as the floating DO threshold of the current monitoring period, where DO_Th is the preset benchmark value of DO threshold. By pre-dividing [0,1] into multiple intervals, each interval corresponds to an upward floating coefficient α. The upward floating coefficient α can be read according to the interval where R1 / M is located.

[0026] In this preferred embodiment, considering the problems of rising water temperature leading to decreased dissolved oxygen saturation, resulting in more severe actual hypoxia at the same DO value; increased organic matter content leading to increased oxygen consumption necessitating a higher control threshold to maintain the hypoxic state; and natural hypoxia at night or in the early morning causing complete anaerobic blackening and sediment decay at a fixed threshold, all these issues would lead to a lower fixed DO threshold than the actual situation. In other words, if adjustment is only made after the fixed DO threshold is reached, it is already too late. Therefore, a more sensitive, i.e., higher DO threshold, is needed. Based on the above considerations, a floating DO threshold is set for each monitoring cycle according to the DO data within the monitoring cycle, thereby enabling intelligent control of the aeration equipment. This avoids frequent start-ups and shutdowns of the aeration equipment and dynamically adjusts the DO threshold. Compared to a fixed threshold method, this balances the influence of environmental factors, making the hypoxic-anaerobic state more accurate. A minimum value principle coefficient is designed to determine when the data in the monitoring cycle tends towards a lower value. The more such data there are, the more it indicates that even if the DO has not reached the minimum threshold, the environment is driving it towards a lower value. Therefore, we need to increase the DO threshold to counteract this change and better maintain the hypoxic-anaerobic state.

[0027] In a preferred embodiment of the present invention, the tailwater treatment zone is a "three-pond, two-dam" system, an artificial wetland, or a moving bed biofilm reactor (MBBR). The tailwater treatment zone is filled with functional biological packing material, which is loaded with highly efficient nitrogen and phosphorus removal bacteria.

[0028] In a preferred embodiment of the present invention, the highly efficient denitrifying and phosphorus-removing bacterial agent is specifically constructed based on a complex microbial community of Pseudomonas, Acinetobacter, and denitrifying bacteria.

[0029] In a preferred embodiment of the present invention, the amount M of the fixed carbon source is calculated as follows: ; Where A is the pond area and ρ is the empirical density coefficient. To preset the carbon-nitrogen ratio, For the estimated initial total nitrogen concentration, This is the theoretical nitrogen conversion efficiency coefficient of the carbon source.

[0030] In this preferred embodiment, the initial total nitrogen load of the water body is used. Based on the target carbon-to-nitrogen ratio required by the system. The theoretical carbon requirement is calculated; the carbon source conversion efficiency coefficient η is introduced to correct the loss and utilization rate of carbon source in practical applications; the empirical density coefficient ρ is used to adapt to the actual working conditions of the project; and the fixed carbon source addition amount M required to meet the anoxic-anaerobic environment regulation is finally obtained by combining the water body size (pond area) A. Based on this, the accurate fixed carbon source addition amount can be obtained.

[0031] Specifically, when applying the method proposed in this invention, taking the treatment of pond effluent from a Litopenaeus vannamei shrimp farming pond as an example, The processing procedure is as follows: 1. Pond conditions: 10 mu in area, with an average water depth of 1.5 meters. After harvesting, the pond is left to stand for 4 days, the top layer of water is drained, and the bottom of the pond is left to accumulate water to a depth of about 0.5 meters.

[0032] 2. Sediment activation: Turn on two waterwheel aerators to vigorously stir for 3 hours to completely suspend the sediment.

[0033] 3. Carbon source addition: Samples were taken to measure the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the mixed water, estimating the initial total nitrogen concentration (N0) to be approximately 35 mg / L. Based on Formula 1, ρ was set to 1 ton / acre. =12, η ​​is taken as 0.8, and the simplified simulation value of the amount of sugarcane bagasse powder (C / N≈12:1, 40 mesh) to be added is about 10 mu × 1 ton / mu × 12 × (35 / 0.8). Based on actual experience, the final amount to be added is 12 tons.

[0034] 4. In-situ denitrification: After adding the carbon source, stop strong aeration. Refer to the installed online DO monitor. Figure 2 The control logic, based on Formula 2, automatically controls a microporous aerator to maintain a slight water flow. After 12 days of treatment, the total nitrogen in the water was measured to have decreased to below 8 mg / L.

[0035] 5. Advanced Treatment: The pond water is discharged into the existing "three ponds and two dams" system. The ecological ponds in this system are filled with biological packing materials loaded with compound microbial agents (including Pseudomonas, Acinetobacter, etc.). After 5 days of flow treatment, the final effluent has a total nitrogen of ≤3mg / L and a total phosphorus of ≤0.5mg / L, meeting the Class II standard of "Freshwater Pond Aquaculture Water Discharge Requirements" (SC / T 9101-2007).

[0036] Comparison of effects: In the same aquaculture farm, another pond with similar conditions was selected as a control. After cleaning the pond, without any in-situ treatment, all the pond water (initially with a total nitrogen of about 28 mg / L) was directly pumped into the same "three ponds and two dams" system.

[0037] Results: After 15 days of treatment using traditional methods, the total nitrogen in the effluent remained as high as 12 mg / L, making it difficult to consistently meet the standards. Furthermore, the treatment system was overloaded.

[0038] Conclusion: The method of this invention eliminates the main pollution load in the pond by pre-treatment in situ enhanced denitrification, thereby significantly improving the treatment effect and stability of the traditional downstream process.

[0039] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment, depending on actual needs.

[0040] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0041] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or system capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0042] Although the description of the invention has been quite detailed and particularly of several described embodiments, it is not intended to limit it to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

[0043] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any embodiment that achieves the technical effects of the present invention using the same means should fall within the protection scope of the present invention. Within the protection scope of the present invention, various modifications and variations can be made to the technical solutions and / or implementation methods.

Claims

1. A method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source regulation and process optimization, characterized in that, Including the following: Step 110: After the aquatic products are harvested, the water in the original aquaculture pond is left to stand still for N days to achieve in-situ sedimentation. Then, the supernatant is discharged and enters the conventional tailwater treatment process, leaving a rich water body of depth H at the bottom of the pond. Step 120: Mechanically disturb the bottom sediment in the enriched water body to fully mix the bottom sediment with the water body to form a homogenized mud-water mixture. Based on the pond area and the estimated initial total nitrogen concentration in the mud-water mixture according to the preset rules, add a carbon source with a preset carbon-nitrogen ratio of M to the current pond. Step 130: After adding the fixed carbon source, turn on the pond aerator for 3-5 days to maintain the dissolved oxygen in the mud-water mixture at no less than 3 mg / L for aerobic biological denitrification. Then turn off the aerator and maintain the pond water in an anoxic-anaerobic state for in-situ anaerobic biological denitrification treatment for a period of T days (T≥10 days). When the total nitrogen in the effluent drops below 10 mg / L, proceed to the next treatment step. Utilizing the cleaned pond for in-situ treatment improves land use efficiency and reduces the area required for subsequent effluent treatment. Step 140: Discharge the water body after the denitrification treatment to the tailwater treatment area for treatment until the total nitrogen, total phosphorus, COD, pH and suspended solids content in the water body reaches the preset discharge standards.

2. The method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to claim 1, characterized in that, Specifically, the value of N ranges from 3 to 5 days, and the value of H ranges from 0.4 to 0.6 meters.

3. The method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to claim 1, characterized in that, Specifically, the fixed carbon source is at least one of sugarcane bagasse powder, straw powder, or cassava residue powder, with a particle size of 20-60 mesh and a carbon-to-nitrogen ratio (C / N) of 10-15:

1.

4. The method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to claim 1, characterized in that, Specifically, the process of maintaining a pond in an anoxic-anaerobic state includes, A preset monitoring cycle is set, and M dissolved oxygen (DO) data are collected in the water body in each monitoring cycle. A floating DO threshold is set for each monitoring cycle based on the DO data within the monitoring cycle. Furthermore, for any monitoring period, the number of data points with DO values ​​lower than the corresponding floating DO threshold is recorded as M1. If M1 is lower than M_Th, it is determined that there is no hypoxia in the current monitoring period, and the oxygenation equipment is turned off in the next monitoring period. If M1 is not lower than M_Th, it is determined that there is hypoxia in the current monitoring period, and the oxygenation equipment is turned on in the next monitoring period, where M_Th is a preset quantity threshold.

5. A method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to claim 4, characterized in that, Specifically, a floating DO threshold is set for each monitoring period based on the DO data within that period, including: Let any monitoring period be [DO_1, DO_2, ..., DO_M], and DO_i, i∈[1,M]; The minimum value of DO_i is calculated as follows: ; Where avg· means to calculate the average value, max· means to calculate the maximum value, and min· means to calculate the minimum value; Then, the number of data corresponding to the small value farth coefficient being less than the preset coefficient threshold in the current monitoring period is counted as R1, and R1 / M is further calculated. The upward floating coefficient α of DO_Th is determined according to the interval where R1 / M is located. Then, (1+α)DO_Th is used as the floating DO threshold of the current monitoring period, where DO_Th is the preset benchmark value of DO threshold. By pre-dividing [0,1] into multiple intervals, each interval corresponds to an upward floating coefficient α. The upward floating coefficient α can be read according to the interval where R1 / M is located.

6. A method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization, as described in claim 1, is characterized in that... Specifically, the tailwater treatment area is a "three pools and two dams" system, an artificial wetland, or a moving bed biofilm reactor (MBBR). The tailwater treatment area is filled with functional biological packing material, which is loaded with highly efficient nitrogen and phosphorus removal bacteria.

7. A method for graded treatment of aquaculture pond clearing wastewater based on precise carbon source control and process optimization according to claim 6, characterized in that, Specifically, the highly efficient nitrogen and phosphorus removal agent is constructed based on a complex microbial community of Pseudomonas, Acinetobacter, and denitrifying bacteria.

8. A device for graded treatment of aquaculture pond clearing wastewater based on precise carbon source regulation and process optimization, characterized in that, Specifically, the amount M of the fixed carbon source added is calculated as follows: ； Where A is the pond area and ρ is the empirical density coefficient. To preset the carbon-nitrogen ratio, For the estimated initial total nitrogen concentration, This is the theoretical nitrogen conversion efficiency coefficient of the carbon source.

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