Dynamic control method applied to aquaculture tail water circulation treatment system

Abstract

The invention relates to the technical field of sewage treatment, in particular to a dynamic control method applied to a culture tail water circulation treatment system. The method comprises the following steps: continuously detecting aquaculture tail water on a water inlet pipeline, calculating the ratio of chemical oxygen demand to five-day biochemical oxygen demand as a first degradation index, and calculating the ratio of ultraviolet absorbance to total organic carbon concentration as a second degradation index; according to the first degradation index and the second degradation index, identifying aging complementary and range complementary organic load degradation characteristics, and determining a process treatment path based on the organic load degradation characteristics; performing primary pretreatment on the aquaculture tail water in different process treatment paths to obtain intermediate water quality data; detecting the ammonia nitrogen concentration of the intermediate water quality data, and extracting the time change rate of the ammonia nitrogen concentration as an ammonia nitrogen conversion parameter. According to the invention, the oxygen utilization efficiency and the removal rate of organic matters and nitrogen are improved through regional dissolved oxygen and function configuration optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a dynamic control method applied to a breeding tail water circulating treatment system. BACKGROUND

[0002] Breeding tail water refers to breeding water discharged to the external environment from a breeding system (a pond, a net cage, a factory workshop, etc.) during or after aquaculture and no longer reused. The breeding tail water contains a large amount of pollutants such as organic matter, ammonia nitrogen and total nitrogen. If the water body is directly discharged without treatment, it will become a “catalyst” of water eutrophication and red tide. However, the existing breeding tail water treatment system mainly relies on a single chemical oxygen demand (COD) or biochemical oxygen demand (5-day) (BOD5) index to judge water quality, and cannot accurately identify the specific characteristics of organic load. The BOD5 detection needs 5 days, and the response lag is serious, so it is difficult to realize real-time control. For different types of organic matter (easily degradable proteins, difficult degradable cellulose, aromatic compounds, etc.) contained in the breeding tail water, the existing technology lacks effective classification and identification means. The traditional treatment system usually adopts a fixed process flow, and cannot dynamically adjust the treatment strategy according to the water quality characteristics. For organic loads with different degradation characteristics, the use of a unified treatment process often leads to low treatment efficiency and high energy consumption. In particular, in different stages of breeding production, the composition of tail water changes significantly, and the fixed process is difficult to adapt to such changes. SUMMARY

[0003] Therefore, it is necessary to provide a dynamic control method applied to a breeding tail water circulating treatment system to solve at least one of the above technical problems.

[0004] To achieve the above-mentioned purpose, a dynamic control method applied to a breeding tail water circulating treatment system comprises the following steps: Step S1: continuously detecting breeding tail water on an inlet pipe, calculating a ratio of chemical oxygen demand to five-day biochemical oxygen demand as a first degradation index, and calculating a ratio of ultraviolet absorbance to total organic carbon concentration as a second degradation index; Step S2: identifying time complementary and range complementary organic load degradation characteristics according to the first degradation index and the second degradation index, and determining a process treatment path based on the organic load degradation characteristics; performing primary pretreatment on the breeding tail water in different process treatment paths to obtain intermediate water quality data; Step S3: detecting an ammonia nitrogen concentration of the intermediate water quality data, and extracting a time variation rate of the ammonia nitrogen concentration as an ammonia nitrogen conversion parameter; Step S4: Gradient dissolved oxygen control processing is performed on the intermediate water quality data using the ammonia nitrogen conversion parameter, and secondary aerobic treatment effluent data is monitored on the effluent pipeline; Step S5: The secondary aerobic treatment effluent data is compared with a preset target, and closed-loop feedback adjustment and load impact protection are performed to realize stable and standard effluent.

[0005] The present application realizes real-time optimization and efficient operation of the aquaculture tail water treatment process by deeply integrating multi-dimensional water quality monitoring and intelligent process adjustment.

[0006] Utilize Multi-parameter collaborative monitoring such as ratio, TOC, UV254, ammonia nitrogen concentration change rate, and combined with sliding time window analysis and abnormal data elimination, ensure that the obtained water quality data is accurate and reliable, and reduce the deviation of control decisions from the source. Through trend stability determination and ammonia nitrogen conversion parameter grading quantification, the system can quickly match the optimal treatment path under different water quality fluctuation states, such as switching to high-intensity oxygenation or increasing anaerobic / anoxic pretreatment during pollution load peaks, thereby improving nitrogen removal efficiency. In terms of dissolved oxygen distribution and regional function division, the proportion of each functional area of the reactor, the oxygen concentration gradient and the aeration mode are dynamically adjusted according to the theoretical oxygen demand, realizing the maximization of oxygen utilization rate, and at the same time ensuring the balance of organic matter degradation and nitrification reaction. The biological membrane thickness self-adaptive regulation mechanism effectively prevents the blockage problem caused by residual feed particles accumulation, and maintains the long-term stable operation of the reactor.

[0007] In addition, the closed-loop feedback adjustment and load impact protection mechanism ensures that the system can immediately increase the treatment intensity and prolong the treatment time when the influent water quality suddenly changes, avoiding over-standard discharge. In summary, this method not only significantly enhances the system's adaptability to water quality fluctuations, reduces energy consumption and maintenance costs, but also can maintain stable and standard effluent in complex and variable aquaculture environments for a long time, taking into account treatment efficiency, operation economy and environmental safety. BRIEF DESCRIPTION OF DRAWINGS

[0008] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings: Fig. 1 The step flow chart of the dynamic control method of the aquaculture tail water recycling treatment system applied by the present application; Fig. 2 The process flow chart of the aquaculture tail water treatment system of one embodiment of the present application; Fig. 3 The sectional view of the secondary aerobic reactor structure of one embodiment of the present application. DETAILED DESCRIPTION

[0009] The technical method of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0010] In addition, the accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. Identical reference signs in the drawings represent identical or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities, which do not necessarily have to correspond to physically or logically independent entities. The functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0011] It should be understood that although the terms "first", "second" and the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the example embodiments. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0012] To achieve the above-mentioned purpose, please refer to Figs. 1 to 3 The present application provides a dynamic control method applied to a breeding tail water circulation treatment system, which comprises the following steps: Step S1: continuously detecting breeding tail water on the water inlet pipeline, calculating the ratio of chemical oxygen demand to five-day biochemical oxygen demand as a first degradation index, and calculating the ratio of nano-ultraviolet absorbance to total organic carbon concentration as a second degradation index; Further, step S1 comprises the following steps: Step S11: setting an automatic sampling device on the water inlet pipeline, automatically collecting water samples every set time to send to a chemical oxygen demand detector and a five-day biochemical oxygen demand detector for offline detection, so as to calculate the ratio of chemical oxygen demand to five-day biochemical oxygen demand as a first degradation index; Step S12: sequentially installing a total organic carbon analyzer and a 254-nanometer wavelength ultraviolet spectrophotometer on the breeding tail water inlet pipeline, and setting a continuous sampling interval of 5-10 minutes; Step S13: continuously detecting the total organic carbon concentration value of the breeding tail water through the total organic carbon analyzer, and synchronously continuously detecting the ultraviolet absorbance value of the breeding tail water at a 254-nanometer wavelength through the 254-nanometer wavelength ultraviolet spectrophotometer; Step S14: Calculate the ratio of UV absorbance value to total organic carbon concentration value as the second degradation index.

[0013] In some embodiments, an online sampling device with an automatic timing control unit is installed upstream of the main inlet pipeline for aquaculture wastewater. This sampling device, in conjunction with an electric valve and a sampling pump, delivers water samples collected every 30 minutes to a chemical oxygen demand (COD) analyzer and a five-day biochemical oxygen demand (BOD) analyzer. The detector was used for offline measurement, and the obtained COD value was compared with... The first degradation index is obtained by performing a ratio calculation on the numerical values. For example, in one embodiment, a COD of 120 mg / L was detected. If the concentration is 80 mg / L, the first degradation index is calculated to be 1.5. Simultaneously, a total organic carbon (TOC) analyzer and a 254 nm wavelength ultraviolet spectrophotometer are installed in series on the influent pipeline approximately 0.5 meters downstream of the automatic sampling point. The system sets the continuous sampling interval between the two devices to 5 minutes and ensures that their sampling ports are adjacent to each other to achieve spatiotemporal consistency of the data. During operation, the TOC analyzer can automatically and continuously detect the total organic carbon concentration in the influent. For example, if the detected value is 25 mg / L, and the absorbance detected by the simultaneous ultraviolet spectrophotometer at 254 nm wavelength is 0.35 Abs, then the second degradation index is calculated to be 0.35 / 25 = 0.014 Abs·L / mg. This ratio can be transmitted to the data processing module in real time and used together with the first degradation index for subsequent identification of organic load degradation characteristics.

[0014] It should be noted that, in order to avoid instantaneous anomalies in the TOC and UV254 detection values ​​due to temperature fluctuations or interference from water sample particles, a short-time moving average filtering algorithm can be set at the signal acquisition end to improve the stability and reliability of the second degradation index.

[0015] Step S2: Identify the time-complementary and range-complementary organic load degradation characteristics based on the first and second degradation indicators, and determine the process treatment path based on the organic load degradation characteristics; perform primary pretreatment on aquaculture wastewater in different process treatment paths to obtain intermediate water quality data; Further, in step S2, identifying time-complementary and range-complementary organic load degradation characteristics based on the first and second degradation indices includes: The organic load is initially predicted by using the rapid detection characteristics of the second degradation index. When the value of the second degradation index is greater than the preset aromaticity threshold, it is predicted that it contains recalcitrant aromatic components. When the value of the second degradation index is less than or equal to the preset aromaticity threshold, it is predicted that the content of aromatic components is low, thus obtaining the aromaticity characteristics. The organic load was fully verified by utilizing the full-spectrum detection characteristics of the first degradation index. When the value of the first degradation index was greater than the preset biodegradability threshold, it was verified as a difficult-to-degrade organic load. When the value of the first degradation index was less than or equal to the preset biodegradability threshold, it was verified as an easily degradable organic load, thus obtaining the degradation load characteristics. When the aromaticity characteristics show a low content of aromatic components and the degradation load characteristics show an easily degradable organic load, the organic load degradation characteristics are determined to be of the easily degradable type. When the aromaticity characteristics indicate the presence of recalcitrant aromatic components and the degradation load characteristics indicate a recalcitrant organic load, the organic load degradation characteristics are determined to be of the recalcitrant type. When the aromaticity characteristics show a low content of aromatic components but the degradation load characteristics show a recalcitrant organic load, the organic load degradation characteristics are determined to be of the non-aromatic recalcitrant type. When aromaticity and degradation load characteristics have other combinations, the organic load degradation characteristics are determined to be of a mixed type.

[0016] In some embodiments, to achieve both rapid and reliable organic load determination, a second degradation index is first used in practice ( Continuous rapid screening is performed (sampling interval 5–10 minutes). When the ratio exceeds a preset aromaticity threshold (e.g., 0.02), it is presumed to contain recalcitrant aromatic components; when the ratio is less than or equal to the threshold, it is presumed to contain low levels of aromatic components. Subsequently, the first degradation index (…) is used… Perform full-spectrum validation (from results of automated sampling and offline detection, e.g., every 30 minutes): When When the value exceeds a preset biodegradability threshold (e.g., 2.0), it is verified as difficult to degrade, which helps correct short-term misjudgments of the second indicator; when When the content is less than or equal to the threshold, it is verified as easily degradable. The judgment logic maps the combination of two characteristics into four categories: if the aromaticity characteristic shows low content and the degradation load shows easily degradable, it is classified as easily degradable; if both show difficult degradation, it is classified as difficult degradable; if the aromaticity is low but the degradation load is difficult degradable, it is classified as non-aromatic difficult degradable; the rest are classified as mixed types.

[0017] In some embodiments, if TOC = 25 mg / L and UV254 = 0.35 Abs, then the second index = 0.35 ÷ 25 = 0.014 (less than 0.02), indicating a low content of aromatic components; if COD = 120 mg / L, =80mg / L, then the first indicator =120÷80=1.5 (≤2.0), which verifies that it is easily degradable, and it is finally determined to be of the easily degradable type.

[0018] In other embodiments, TOC = 20 mg / L, UV254 = 0.5 Abs → second index = 0.5 ÷ 20 = 0.025 (>0.02), initially judged to contain aromatic and difficult-to-degrade substances; if COD = 180 mg / L, =60mg / L→First index=180÷60=3.0 (>2.0) Verification indicates it is difficult to degrade, and it is finally determined to be a difficult-to-degrade type; if the second index is low (e.g. 0.0075) but the first index is high (e.g. 3.333…), it is treated as a non-aromatic difficult-to-degrade type; other combinations are recorded as mixed types.

[0019] It should be noted that the threshold should be adjusted according to the local tailwater characteristics and equipment calibration; to reduce the impact of instantaneous noise or particulate matter interference on the second indicator, short-time moving average or filtering can be used for continuous readings; in addition, after the first indicator is updated, the system should be allowed to confirm or correct the initial judgment once, so as to avoid frequently switching the process treatment path in a short period of time, so as to seamlessly connect with the subsequent steps (selecting the corresponding pretreatment path according to the judgment result).

[0020] Furthermore, step S2, which determines the process path based on the degradation characteristics of organic load, includes: When the organic load degradation characteristics are easily degradable, the direct aerobic treatment path is selected, and the parameter combination is set as follows: hydraulic retention time 1.0-2.0 hours, dissolved oxygen concentration 1.8-2.8 mg / L, and hydrogen ion concentration index 7.0-7.5. When the organic load degradation characteristics are recalcitrant, the hydrolysis acidification pretreatment path is selected, and the parameter combination is set as follows: hydraulic retention time 6.5-8.5 hours, dissolved oxygen concentration less than 0.08 mg / L, and hydrogen ion concentration index 6.6-7.0. When the organic load degradation characteristics are non-aromatic and difficult to degrade, an enhanced hydrolysis pretreatment path is selected, and the parameter combination is set as follows: hydraulic retention time 5.0-7.0 hours, dissolved oxygen concentration 0.1-0.3 mg / L, and hydrogen ion concentration index 6.8-7.2. When the degradation characteristics of organic load are mixed, select the anoxic pretreatment path and set the parameter combination as follows: hydraulic retention time 5.0-7.0 hours, dissolved oxygen concentration 0.1-0.3 mg / L, and hydrogen ion concentration index 6.8-7.2. The selected processing path and the corresponding parameter combination are used as the process processing path and transmitted to the control center of the primary pretreatment reactor.

[0021] In some embodiments, based on the previously determined organic load degradation characteristics as triggering conditions, the corresponding pretreatment process is automatically selected, and the complete parameter combination is sent as a "process package" to the control center of the primary pretreatment reactor (transmitted via the plant control network / PLC-SCADA interface) to achieve equipment linkage and parameter readiness. This process package includes: target hydraulic retention time (controlled by influent flow rate or adjusted by a distribution valve), dissolved oxygen setpoint or control range, etc. Set the range and corresponding buffer and dosing rate, start / stop logic and operating parameters of equipment such as agitator / aeration / internal circulation / heating (e.g., agitator speed, aeration mode and cycle, reflux ratio, etc.). For example: If determined to be easily degradable, the control center issues HRT=1.0–2.0h (example: 1.5h), DO setting 1.8–2.8mg / L (example: 2.2mg / L), pH 7.0–7.5, and automatically starts pre-aeration (2–5min), starts the high-speed agitator at 150–200rpm, and simultaneously starts the NaOH dosing pump to maintain pH; if determined to be difficult to degrade (aromatic), issues HRT=6.5–8.5h (example: 7.0h), DO <0.08mg / L, etc. For non-aromatic, recalcitrant or mixed-type hydrolysis, the following control strategies are implemented: pH 6.6–7.0; regular aeration is disabled; anaerobic stirring (60–80 rpm) is initiated; nitrogen purging and heating (35–40°C, example) are activated; and sodium bicarbonate buffer is added. For hydrolysis-enhanced or anoxic hydrolysis, the corresponding HRT (5.0–7.0 h), low DO (0.1–0.3 mg / L), and pH 6.8–7.2 are issued. Appropriate phosphate / mixed buffer addition, intermittent aeration, or internal circulation (200–300% reflux ratio, example) are also implemented. The control center simultaneously records the issued commands and monitors equipment response and real-time water quality feedback data for subsequent verification and necessary adjustments.

[0022] It should be noted that, in order to avoid frequent process switching due to short-term fluctuations in influent, a confirmation window or lag mechanism should be set between the judgment and the issuance, and manual verification should be allowed. In addition, the control and measurement of ultra-low DO (<0.08mg / L) has high requirements for sensor accuracy and calibration. The dosing formula and equipment parameters should be fine-tuned based on local calibration curves and operating experience.

[0023] Furthermore, in step S2, the aquaculture wastewater undergoes a process treatment procedure to obtain intermediate water quality data, including: Aquaculture wastewater is introduced into a primary pretreatment reactor. The equipment combination is started and the operating parameters are set according to the process treatment path to obtain the corresponding reactor operating status. In the operating state of the reactor, the primary pretreatment reactor performs biochemical treatment on the aquaculture wastewater to adjust the hydrogen ion concentration index to the target range and obtain standard wastewater with hydrogen ion concentration. Specifically, the biochemical treatment involves adding sodium hydroxide solution in the direct aerobic treatment path, adding sodium bicarbonate buffer in the hydrolysis acidification pretreatment path, adding phosphate buffer in the enhanced hydrolysis pretreatment path, and adding mixed buffer in the anoxic pretreatment path. By installing monitoring devices in the reactors of each process path, the hydrogen ion concentration standard tailwater is monitored in real time. The direct aerobic treatment path monitors dissolved oxygen and pH value, the hydrolysis acidification pretreatment path monitors temperature and redox potential, the enhanced hydrolysis pretreatment path monitors enzyme activity and particle size, and the anoxic pretreatment path monitors dissolved oxygen change cycle and circulation flow rate, thus obtaining a real-time parameter set. Chemical oxygen demand (COD) and total organic carbon (TOC) concentrations were measured at the effluent outlet of the primary pretreatment reactor. The treatment effect was verified by combining the real-time parameter set, and intermediate water quality data were obtained.

[0024] In some embodiments, the aquaculture wastewater from the main inlet pipeline is introduced into the primary pretreatment reactor through a controlled flow valve or regulating pump. The control center starts the corresponding equipment combination with one click according to the issued "process package" and sets the operating parameters (including target hydraulic retention time, stirring speed, aeration mode / blower speed, internal circulation ratio, temperature control setting, and the dosing rate of each buffer / alkali solution, etc.) to put the reactor into the corresponding operating state. In the operating state, the pH adjuster is precisely added according to the process path through the dosing system—the direct aerobic path turns on the sodium hydroxide dosing pump as needed to maintain the pH in the range of 7.0–7.5; the hydrolysis acidification path adds sodium bicarbonate buffer at a set rate and turns off conventional aeration while starting anaerobic stirring and controlling the temperature; the enhanced hydrolysis path adds phosphate buffer and maintains low DO and moderate stirring; the anoxic path adds formulated mixed buffer and configures intermittent aeration and high internal circulation; and online and offline systems are used simultaneously. A monitoring network composed of field sensors monitors the "hydrogen ion concentration standard effluent" in real time. The direct aerobic pathway focuses on collecting DO and pH values, the hydrolysis acidification pathway focuses on collecting temperature and oxidation-reduction potential (ORP), the enhanced hydrolysis pathway uses enzyme activity sensors or representative biochemical rate indicators and particle size measurement devices to monitor bacterial activity and solid phase characteristics, and the anoxic pathway monitors the DO change cycle and circulation flow rate to confirm the alternating aerobic / anoxic microenvironment. At the reactor effluent outlet, chemical oxygen demand (COD) and total organic carbon (TOC) are measured at predetermined frequencies (which can be done using an online analyzer or a combination of automatic sampling and offline detection). The COD / TOC test results of the effluent are coupled with the real-time parameter set in the reactor in the data processing module for analysis and treatment effect verification (e.g., comparing the removal rate, pH stability, temperature, and ORP under the target HRT to see if they are within the target window). Finally, intermediate water quality data is generated for transfer to secondary treatment. For example, when the direct aerobic pathway is determined, the system can issue an HRT of 1.5h, a stirring speed of 180rpm, a DO setting of 2.2mg / L, and a pH target of 7.2, and automatically start the NaOH dosing (example reference dosing rate 0.5–1.0mL / min, actual dosing adjusted according to influent alkalinity). The system will also read the COD / TOC at the outlet every hour. If the effluent COD drops from 120mg / L to 60mg / L and the TOC drops from 25mg / L to 10mg / L, the intermediate water quality data will be recorded as meeting the standards and reported. If the expected results are not met, parameter adjustments or alarms will be triggered.

[0025] It should be noted that the precise dosage of buffer and alkali solution should be determined by calibration based on the influent alkalinity, total alkalinity and instantaneous pH response curves; some monitoring methods, such as enzyme activity or particle size, may use representative sampling and rapid detection methods instead of real-time online sensors. The system should consider detection lag and sampling retention time in the control strategy to ensure that the effluent monitoring values ​​are time-aligned with the reactor operating status.

[0026] Most importantly, the process of introducing aquaculture wastewater into the primary pretreatment reactor, starting the equipment combination and setting the operating parameters according to the process treatment path, and obtaining the corresponding reactor operating status are specifically as follows: In the direct aerobic treatment path, the pre-aeration device is started to pre-aerate the incoming aquaculture wastewater for 2-5 minutes to achieve rapid homogenization. At the same time, a high-speed agitator is used to fully mix the wastewater at a speed of 150-200 rpm, and the influent flow rate is adjusted to keep the hydraulic retention time at 1.0-2.0 h, so as to obtain the reactor operation state that meets the requirements of direct aerobic treatment. During the hydrolysis acidification pretreatment process, all aeration equipment is shut down and the anaerobic agitator is started and slowly stirred at a low speed of 60-80 rpm. Nitrogen is introduced into the reactor to replace dissolved oxygen to below 0.08 mg / L, and the heating device is started to control the reactor temperature at 35-40℃ to promote the activity of anaerobic bacteria, so as to obtain a reactor operating state that meets the requirements of hydrolysis acidification treatment. In the anoxic pretreatment pathway, an intermittent aeration mode is adopted, alternating between aeration for 15 minutes and aeration stopping for 45 minutes. At the same time, the internal circulation pump is started to continuously circulate at a reflux ratio of 200-300%, so as to form an alternating aerobic-anoxic microenvironment in the reactor and obtain a reactor operating state that meets the requirements of anoxic pretreatment.

[0027] In some embodiments, after the control center introduces the influent into the primary reactor via PLC / SCADA, it activates the corresponding equipment combination and enters the corresponding operating condition with one click based on the judgment result: For the direct aerobic treatment path, the workshop pre-aeration device is first started to aerate the incoming effluent for 2–5 minutes to achieve rapid homogenization (the aerator operates at low airflow pulse to avoid excessive oxygen enrichment). At the same time, the high-speed agitator is started and the speed is set to 150–200 rpm to ensure thorough solid-liquid mixing. The influent pump or diversion valve is adjusted to match the reactor volume with the influent flow rate, and the hydraulic retention time is maintained at 1.0–2.0 h (e.g., reactor volume). Water inflow The DO controller then maintains dissolved oxygen within a set range (e.g., For the hydrolysis-acidification pretreatment path, close all conventional aeration valves and activate the anaerobic agitator. Slow mixing at low speed, with dissolved oxygen reduced to below 0.08 mg / L by nitrogen purging or displacement, and maintaining a closed or slightly displaced gas phase to prevent oxygen re-dissolution, while simultaneously starting the heating device to control the reactor temperature at 35–40°C to promote the activity of hydrolytic and acidifying bacteria (e.g., reactor volume). , water inlet →HRT≈7.0h, stirring at 70rpm, initial nitrogen purging flow rate can be set to 5L / min until DO is below 0.05mg / L); For the anoxic pretreatment path, timed intermittent aeration is adopted—the cycle of 15min aeration / 45min stop is achieved by the coordinated output of PLC timer and aeration valve or blower, while the internal circulation pump is started to continuously circulate at a 200-300% reflux ratio to create an alternating aerobic / anoxic microenvironment (e.g., influent). Reflux → Reflux ratio 300%), the redox state at each stage is monitored in real time by DO and ORP sensors, and the aeration time and reflux flow rate are finely adjusted accordingly to ultimately achieve the required operating state for each path. Throughout the process, the control system should record operating parameters, real-time water quality and equipment status, and trigger adaptive adjustment or alarm when steady state is reached or when the set threshold is deviated.

[0028] It should be noted that operations such as ultra-low DO control, nitrogen purging, and heating have high requirements for gas supply, sealing, and sensor accuracy. During implementation, sensor calibration, gas handling, and safe ventilation should be carried out, and hysteresis and confirmation windows should be set to avoid frequent switching of process conditions due to instantaneous reading fluctuations.

[0029] Step S3: Detect the ammonia nitrogen concentration in the intermediate water quality data and extract the time change rate of ammonia nitrogen concentration as an ammonia nitrogen conversion parameter; Furthermore, step S3 includes the following steps: Step S31: Install an online ammonia nitrogen analyzer 0.5-1.0 meters away from the inlet of the secondary aerobic reactor in the inlet pipeline, set the detection interval to 10-15 minutes, continuously detect the ammonia nitrogen concentration value of intermediate water quality data, and record the timestamp of each detection to obtain a time-stamped ammonia nitrogen concentration sequence data; Step S32: When any value in the ammonia nitrogen concentration sequence data deviates from its adjacent value by more than 30%, it is marked as abnormal data; Step S33: When abnormal data is detected, the repeated detection mechanism is activated. The median of the three consecutive detections is taken as the effective value at the current moment, thus obtaining a reliable ammonia nitrogen concentration time series. Step S34: Use the ammonia nitrogen concentration time series to extract ammonia nitrogen conversion parameters and obtain graded and quantified ammonia nitrogen conversion parameters.

[0030] In some embodiments, an online ammonia nitrogen analyzer is fixedly installed 0.5–1.0 m from the inlet of the secondary aerobic reactor in the inlet pipe and connected to the PLC / SCADA data bus. The instrument automatically samples at a detection interval of 10–15 min and records each detection value along with a precise timestamp into the database to form a time-stamped ammonia nitrogen sequence. The system performs real-time anomaly detection on the received sequence: if any measurement value differs from its adjacent values ​​by more than 30% (either absolute or relative percentage can be set), the point is marked as "abnormal," and a re-detection mechanism is automatically triggered—three consecutive rapid acquisitions are made at the same time position, and the median is reported as the valid value for the current time, thereby replacing the original abnormal point to ensure sequence quality. Subsequently, at the data processing end, the ammonia nitrogen conversion parameters are extracted with an analysis window of approximately 1 hour (if the sampling interval is 10 min, the window can take the most recent 6 points; if it is 15 min, it takes 4 points). Linear least squares fitting is performed on the time-stamped data within the window to obtain the slope of the ammonia nitrogen concentration over time during that period (using...). The original change rate (in units of 1.5) is used as the initial change rate, and the standard deviation of the change rate over the past hour is calculated as the change rate fluctuation coefficient to assess trend stability (fluctuation coefficient <0.15 is considered stable, >0.25 is considered volatile, and between the two is considered transitional). A confidence weight is assigned to the change rate based on stability (e.g., 1.0 for stability, 0.75 for transitional, and 0.5 for volatility; specific values ​​can be calibrated based on field experience). The original change rate is multiplied by this weight to obtain the trend-corrected ammonia nitrogen change rate. Finally, it is quantified and converted into ammonia nitrogen conversion parameters according to absolute value: when the change rate is negative and the absolute value is... Determined as a high-intensity conversion parameter, with an absolute value in Determined as moderate intensity, absolute value The intensity is determined to be low, and the grading and quantification parameters (including the rate of change, stability indicator, and timestamp) are sent to the secondary aerobic reactor via the communication interface for dissolved oxygen regulation and aeration strategy adjustment. Example: If online readings are taken at 10-minute intervals of 10.0, 9.0, 8.0, 6.0, 4.0, and 3.0 mg / L, then a linear fit of the last six points yields a slope of approximately... (High intensity), if the standard deviation of the rate of change in the same period is <0.15, then the weight is ≈1.0, and the high intensity conversion parameter is finally reported; Another example of anomaly handling: if two adjacent points are 2.0 and 2.7 (increase of 35%), the system marks it as an anomaly and immediately repeats the sampling to obtain 2.6, 2.65, and 2.70, and takes the median of 2.65 as the effective value to replace the original anomaly point.

[0031] It should be noted that all thresholds (30% for anomaly detection, sliding window length, stability limits and confidence weights, etc.) should be calibrated and adjusted according to the accuracy of on-site sensors, sampling delay and characteristics of aquaculture wastewater; in addition, diagnostic logic for sensor drift and fouling, data time alignment (sampling lag compensation) and lag / acknowledgment mechanisms to avoid frequent control strategy switching due to short-term noise should be considered.

[0032] Further, step S34 includes the following steps: Step S341: Use a predetermined number of consecutive detection points in the ammonia nitrogen concentration time series to form a sliding time window, and calculate the linear relationship between ammonia nitrogen concentration and time within the window. Use the slope of the fitted line as the rate of change of ammonia nitrogen concentration in that time period. Step S342: Calculate the standard deviation of the rate of change of ammonia nitrogen concentration in the past hour, and record it as the rate of change fluctuation coefficient; Step S343: When the rate of change fluctuation coefficient is less than 0.15, it is determined to be a stable trend; when the rate of change fluctuation coefficient is greater than 0.25, it is determined to be a fluctuating trend; when the rate of change fluctuation coefficient is between 0.15 and 0.25, it is determined to be a transitional trend. Record the trend stability. Step S344: Assign a confidence weight to the ammonia nitrogen concentration change rate based on trend stability to obtain the trend-corrected ammonia nitrogen change rate; Step S345: When the ammonia nitrogen change rate is negative and the absolute value is greater than 5 mg / L / h, it is set as a high-intensity conversion parameter; when the absolute value of the ammonia nitrogen change rate is between 2 and 5 mg / L / h, it is set as a medium-intensity conversion parameter; when the absolute value of the ammonia nitrogen change rate is less than 2 mg / L / h, it is set as a low-intensity conversion parameter. The graded and quantified ammonia nitrogen conversion parameters are obtained and transmitted to the secondary aerobic reactor through the communication interface.

[0033] In some embodiments, a predetermined number of consecutive ammonia nitrogen detection points are taken in the form of a "sliding time window" at the data processing end. For example, but not limited to, 6 points are taken to form a 1-hour window when the sampling interval is 10 minutes; if the sampling interval is 15 minutes, 4 points are taken; the timestamp of each detection point is converted to hours (e.g., ...). Then, a linear least squares fit is performed on the concentration-time pair within the window. The slope of the fitted line is the rate of change of ammonia nitrogen concentration during that time period (in mg / L·h). For example, assuming the concentration at 6 points in a 10-minute interval is [10.0, 9.2, 8.5, 7.6, 6.8, 6.0] mg / L, the slope can be approximated using the first and last points as (6.0-10.0)÷1.0h=-4.0mg / L·h (as the rate of change for that window). This is the implementation of step S341. Next, according to step S342, a series of short-term rates of change are calculated in the most recent hour for fluctuation assessment. For example, but not limited to, a simple and commonly used method is to calculate the instantaneous rate of change between two adjacent points and convert it to mg / L·h. In this example, the change and conversion between two adjacent points are as follows: the first segment 9.2-10.0=-0.8mg / L, converted to an hourly rate. mg / L·h; Paragraph 2 Paragraph 3 Paragraph 4 Paragraph 5 The instantaneous rate sequence is obtained. mg / L·h; When calculating the standard deviation of this series (denoted as the rate of change fluctuation coefficient), first calculate the mean: (-4.8-4.2-5.4-4.8-4.8)=-24.0, mean= The sum of squares of each deviation is ,variance Standard deviation = mg / L·h; compare with the threshold in step S343 (<0.15 stable, >0.25 fluctuating, 0.15–0.25 transitional). In this example, 0.38>0.25, so it is determined to be a fluctuating trend and the stability is recorded as "fluctuating". According to step S344, a confidence weight is assigned based on trend stability (an empirical weight of 1.0 for steady state, 0.75 for transition, and 0.5 for fluctuation can be used). In this example, the weight is 0.5. Therefore, the original change rate obtained in step S341, -4.0 mg / L·h, is multiplied by 0.5 to obtain the trend-corrected ammonia nitrogen change rate -4.0 × 0.5 = -2.0 mg / L·h. Finally, according to step S345, the corrected change rate is classified: if the change rate is negative and the absolute value is >5, it is high intensity; 2–5 is medium intensity; and <2 is low intensity. Therefore, in this example, |-2.0| = 2.0 mg / L·h falls into the medium intensity conversion parameter range. The system will send (corrected change rate value, intensity level, stability identifier, timestamp, and corresponding original sequence metadata) to the secondary aerobic reactor through the communication interface for aeration / dissolved oxygen control decision-making.

[0034] It should be noted that the above calculation methods for sliding window length, sampling interval, instantaneous rate, and standard deviation are examples based on the "population standard deviation". The threshold (0.15 / 0.25), window size, and weight should be calibrated according to the on-site sensor accuracy, sampling strategy, and dynamic characteristics of aquaculture wastewater. In the case of outliers or sensor drift, it is advisable to perform outlier filtering (such as median filtering) first and pay attention to time alignment to avoid incorrect judgments due to sampling lag.

[0035] Step S4: Use ammonia nitrogen conversion parameters to perform gradient dissolved oxygen regulation on intermediate water quality data, and monitor the secondary aerobic treatment effluent data on the effluent pipeline; Further, step S4 includes the following steps: Step S41: Convert the received ammonia nitrogen conversion parameters into ammonia nitrogen conversion oxygen demand coefficients, read the chemical oxygen demand (COD) value from the intermediate water quality data, and calculate the COD removal oxygen demand based on the theoretical ratio that 1.2 mg / L of dissolved oxygen is consumed to remove 1 mg / L of COD, thus obtaining the organic matter degradation oxygen demand value. Step S42: Calculate the oxygen demand for carbon oxidation based on the empirical ratio that 1 mg / L of total organic carbon requires 1.8 mg / L of dissolved oxygen, using the total organic carbon concentration value from the intermediate water quality data; Step S43: The oxygen demand coefficient for ammonia nitrogen conversion, the oxygen demand value for organic matter degradation, and the oxygen demand value for carbon oxidation are weighted and calculated to obtain the theoretical dissolved oxygen demand value. The weighted calculation is (oxygen demand for organic matter degradation + oxygen demand for carbon oxidation) × oxygen demand coefficient for ammonia nitrogen conversion × 1.2. Step S44: Based on the theoretical dissolved oxygen demand, the dissolved oxygen gradient of the secondary aerobic reactor is set in different zones. The reactor is divided into three zones along the water flow direction: the front high load zone, the middle transition zone, and the rear fine treatment zone, thus obtaining the zoned dissolved oxygen control scheme. Step S45: Under the control of the regional dissolved oxygen control scheme, the intermediate water quality data is subjected to aerobic biological treatment, and the biofilm thickness adaptive regulation mechanism is activated at the same time to obtain real-time monitoring data of the treatment process; Step S46: Pre-evaluate the treatment effect of real-time monitoring data during the treatment process, and test the effluent quality in the effluent pipeline of the secondary aerobic reactor. Compare and verify the pre-evaluation results with the actual test data to obtain the effluent data of the secondary aerobic treatment.

[0036] Most importantly, the biofilm thickness adaptive regulation mechanism is as follows: based on the characteristic that residual feed particles in aquaculture tailwater can easily cause excessive biofilm thickening, an adaptive regulation mechanism for hydraulic flushing intensity is activated to prevent excessive biofilm clogging by adjusting the water flow velocity and aeration intensity in each area.

[0037] In some embodiments, the ammonia nitrogen conversion parameter is mapped to the ammonia nitrogen conversion oxygen demand coefficient (for ease of engineering implementation, high / medium / low intensity can be mapped to 1.4 / 1.2 / 1.0 respectively based on experience, but should ultimately be corrected according to on-site calibration). Then, the COD and TOC values ​​in the intermediate water quality are read and the oxygen demand is calculated according to regulations: Oxygen demand removed by chemical oxygen demand = COD × 1.2 ( The oxygen requirement for carbon oxidation = TOC × 1.8 After adding the two to obtain the basic organic oxygen demand, the theoretical dissolved oxygen demand is calculated using the formula (organic matter degradation oxygen demand + carbon oxidation oxygen demand) × ammonia nitrogen conversion oxygen demand coefficient × 1.2. This value is then used to drive the zonal DO gradient setting and aeration strategy. For example: If the intermediate water quality has COD = 3.0 mg / L and TOC = 1.0 mg / L, first calculate the organic matter degradation oxygen demand = 3.0 × 1.2 = 3.6 mg / L, and the carbon oxidation oxygen demand = 1.0 × 1.8 = 1.8 mg / L, totaling 5.4 mg / L. If the ammonia nitrogen conversion coefficient is taken as an average of 1.2, then the theoretical dissolved oxygen demand = 5.4 × 1.2 × 1.2 = 7.776 mg / L (approximately 7.78 mg / L). The threshold is then determined according to step S44 (>8 / 4 – 8 / <4). If the value falls within the 4–8 mg / L range, the reactor is divided into zones with a length ratio of 3:4:3 (high load at the beginning / transition in the middle / fine treatment at the end). The DO target is then allocated to each zone according to the load (which can be set according to a load weight of 40%:35%:25%). The corresponding target DO is approximately 3.11 mg / L for the beginning zone, 2.72 mg / L for the middle zone, and 1.94 mg / L for the end zone. The control layer uses a zone DO controller, a variable frequency blower, and adjustable aerators (alternating between large bubbles and microbubbles) to achieve the desired DO levels. The system sets up and simultaneously activates an adaptive biofilm thickness control mechanism. This mechanism uses biofilm thickness probes or replacement quantities (such as zone pressure difference, effluent turbidity increase, DO gradient anomaly, or biofilm thickness measured by representative sampling) as trigger signals. When a threshold is reached, it automatically increases the local water flow velocity (adjusts the reflux / bypass valve or briefly increases the internal circulation pump speed), briefly increases the aeration intensity, or initiates pulsed high-shear aeration for hydraulic flushing. When necessary, it triggers periodic backwashing / scraping operations to prevent clogging. Throughout the aerobic treatment process, the system collects real-time monitoring data on DO, ORP, MLSS / biofilm indicators, flow rate, and effluent COD / TOC. First, a pre-assessment of the treatment effect is performed at the control end (based on the current DO and kinetic model to predict effluent indicators). Then, actual online / offline detection is performed on the effluent pipeline of the secondary reactor, and the measured values ​​are compared with the pre-assessment results (if the error exceeds the limit, a feedback command is automatically sent to the upper level to adjust the aeration, reflux ratio, or add auxiliary materials to the primary stage). Finally, the effluent data of the secondary aerobic treatment is generated and recorded as the basis for closed-loop control.

[0038] It should be noted that the above coefficients (1.2, 1.8, ammonia nitrogen coefficient mapping), windows and weights are implementation examples. Before the project is implemented, tests and calibrations should be conducted in conjunction with the influent characteristics, aeration equipment capacity and safety margin of the site. At the same time, attention should be paid to the air supply capacity limitations of blowers and microbubble devices, avoiding dissolved oxygen oversaturation or local hypoxia, and ensuring the reliability of biofilm detection and valve pump response to avoid malfunctions.

[0039] Further, step S44 includes: Based on the theoretical dissolved oxygen demand, the reactor is divided into functional zones. When the demand is greater than 8 mg / L, the reactor is divided into a high-load zone, a transition zone, and a fine treatment zone in a 4:3:3 ratio. When the demand is between 4 and 8 mg / L, the zone is divided in a 3:4:3 ratio. When the demand is less than 4 mg / L, the zone is divided in a 2:4:4 ratio, thus obtaining the zone length configuration scheme. Based on the regional length configuration scheme, adjustable baffles are installed in the reactor, and dissolved oxygen concentration transition buffer zones are set at the boundaries of each region. The length of the buffer zone is set to 10-15% of the length of the adjacent region, resulting in a physical partition structure layout. By using alternating large and microbubbles for aeration, rapid protein decomposition aeration is carried out in the high-load zone at the front end, resulting in a dedicated aeration configuration for the front end area. In the intermediate transition zone, when the carbon-nitrogen ratio is detected to be lower than 8:1, a carbon source is automatically added; when the carbon-nitrogen ratio is higher than 15:1, the aeration intensity is increased to obtain a balanced regulation configuration in the intermediate zone. Periodic configuration is carried out in the downstream fine treatment area. During the peak period of fish water exchange, fine filtration devices and deep aeration equipment are added, and intermittent aeration mode is used during other periods to obtain the periodic adaptive configuration of the downstream area. A regional dissolved oxygen control scheme is formed based on the physical zoning structure layout and the configuration scheme of each region.

[0040] In some embodiments, the zoning ratio is determined based on the theoretical dissolved oxygen requirement, and the reactor is physically divided along the water flow direction into a high-load front zone, a transition zone, and a fine treatment zone: for example, when the theoretical requirement is 7.78 mg / L (falling within the 4–8 mg / L range), the zone is divided in a 3:4:3 ratio—if the total length of the reactor is 12.0 m, then the front zone is 3.6 m, the middle zone is 4.8 m, and the rear zone is 3.6 m; adjustable baffles (such as electric sliding plates or flaps) are installed at the boundaries of each zone to facilitate... The interval length is fine-tuned as needed, and a dissolved oxygen concentration transition buffer zone is set at each boundary. The length of the buffer zone is 10-15% of the length of the adjacent zone (in this example, the front / middle buffer zone = 3.6m × 10% = 0.36m, and the middle / rear buffer zone = 4.8m × 10% = 0.48m), to achieve a smooth transition of DO through physical and hydrodynamic means. The front section uses alternating aeration of large bubbles and microbubbles to balance the shear / mixing requirements of rapid protein decomposition and efficient oxygen transport (for example, large bubble coarse aeration can be set). The microbubble aeration system operates in 10-minute alternating cycles, using a variable frequency blower and a switchable diffuser assembly. The dissolved oxygen (DO) in this zone is set to a load-guided value (which can be allocated according to load weight; for example, in this case, it's allocated as front:middle:back = 40%:35%:25, corresponding to approximately 3.11 mg / L for the front, 2.72 mg / L for the middle, and 1.94 mg / L for the back). The middle zone serves as a balance zone, where the carbon-to-nitrogen ratio is calculated in real-time (derived from online TOC and ammonia / total nitrogen sensors). When C:N < 8:1, the carbon source dosing system (e.g., a metering pump for methanol or acetate solution) is automatically activated to raise the ratio to the target range (example target 10–12:1). When C:N > 15:1, the aeration intensity and duration are increased to promote further aeration. Oxidation removal; the subsequent section is the fine treatment zone, which can automatically activate fine filtration devices (such as drum filters or microfiltration modules) and start deep aeration devices during peak fish water exchange periods to increase local DO to >4mg / L to cope with short-term high loads. During off-peak periods, intermittent aeration mode is adopted, which can stop aeration for 45 minutes after every 15 minutes of aeration to save energy and maintain the stability of the effluent. All zones are equipped with distributed DO / ORP / flow and turbidity sensors. The baffles, aeration volume and dosing pumps are regulated by PLC / SCADA closed loop. The control strategy contains two layers of logic: feedforward (based on theoretical DO demand) and feedback (based on real-time monitoring) to ensure that each zone works according to the set gradient and triggers protective actions such as biofilm flushing, backwashing or carbon source addition.

[0041] It should be noted that the above partition ratios, buffer zone lengths, aeration alternation cycles, carbon source types, and addition targets are only implementation examples. In actual engineering, adjustments should be made based on reactor geometry, aeration and reflux equipment capacity, particle and solid load characteristics, and on-site calibration curves. Baffles and buffer zones will occupy the effective reaction volume. During the design, HRT should be adjusted simultaneously, and attention should be paid to solid retention and ease of maintenance to prevent blockage or disruption to farm operation.

[0042] Step S5: Compare the effluent data from the secondary aerobic treatment with the preset target, and perform closed-loop feedback adjustment and load shock protection to achieve stable effluent that meets the standards.

[0043] Further, step S5 includes the following steps: Step S51: Compare the effluent data from the secondary aerobic treatment with the preset target to obtain the water quality compliance assessment results; Step S52: Based on the water quality compliance assessment results, perform closed-loop feedback adjustment. When the effluent indicators exceed the standards, automatically send parameter adjustment instructions to the upstream treatment unit, including extending the pretreatment time, increasing the dissolved oxygen concentration, or increasing the aeration intensity, and obtain system feedback adjustment instructions. Step S53: Monitor sudden changes in influent load and implement load shock protection. When the influent chemical oxygen demand or ammonia nitrogen concentration increases by more than 20% within 10 minutes, the protection mode is activated, automatically switching the system to high-intensity treatment state and extending the treatment time, thus entering the load shock protection state. Step S54: Achieve stable and compliant effluent under system feedback regulation and load shock protection.

[0044] In some embodiments, the effluent water quality data (such as chemical oxygen demand (COD), ammonia nitrogen) from the secondary aerobic treatment reactor are used. The system compares the concentration of COD (electrochemical oxygen demand) with pre-set water quality standards to assess whether the treatment effect meets environmental emission requirements. For example, if the target COD concentration is 30 mg / L and the measured COD of the effluent is 35 mg / L, it is judged as non-compliant, generating an unqualified water quality assessment result. Based on this assessment result, the system automatically activates a closed-loop feedback regulation mechanism, sending adjustment instructions to the upstream pretreatment unit, such as extending the hydraulic retention time of the pretreatment reactor by 1 hour, increasing the dissolved oxygen concentration to 2.5 mg / L, or increasing the operating intensity of the aeration equipment to enhance the decomposition of organic matter and the conversion of ammonia nitrogen, thereby improving the subsequent treatment effect. The system monitors the influent load in real time. If the influent chemical oxygen demand or ammonia nitrogen concentration is detected to increase by more than 20% in a short period of time (e.g., within 10 minutes), the load shock protection mode is triggered, switching the entire treatment system to a high-intensity operating state, such as doubling the aeration intensity, extending the retention time, and increasing the circulation flow rate, to prevent pollutant overload from causing system failure. Under the synergistic effect of feedback regulation and load protection, the system dynamically adjusts operating parameters to ensure that the effluent water quality consistently meets the standards. For example, during a peak period of aquaculture pond drainage, due to a large influx of feed residue, the system detected that the influent COD rapidly increased from 40 mg / L to 60 mg / L, automatically activated the protection mode and extended the pretreatment time, so that the effluent COD remained below the target value.

[0045] It should be noted that feedback adjustment commands should take into account the operating limits and economy of the equipment to avoid excessive adjustment that could lead to energy waste or equipment damage. At the same time, the threshold and response time of load impact protection should be reasonably set according to the actual operating conditions to avoid false triggering.

[0046] See Fig. 2 The intelligent aquaculture wastewater treatment system provided by this invention includes an aquaculture wastewater raw water tank, an automatic sampling device, a primary pretreatment reactor, an ammonia nitrogen analyzer, a secondary aerobic reactor, and an effluent discharge system. The aquaculture wastewater raw water tank collects wastewater from the aquaculture farm, providing a stable water source for the entire treatment system. The wastewater is transported from the raw water tank to the subsequent treatment units via an inlet pipeline. The automatic sampling device is installed on the inlet pipeline and has an automatic sampling function at 30-minute intervals. The automatic sampling device can periodically collect water samples and send them to a chemical oxygen demand (COD) analyzer and a five-day biochemical oxygen demand (BOD5) analyzer, respectively. The system employs an offline detector and a continuous online total organic carbon (TOC) analyzer and a 254 nm ultraviolet spectrophotometer for calculating the first and second degradation indices. The primary pretreatment reactor is the core pretreatment unit, containing four different process pathways: direct aerobic treatment, hydrolysis-acidification pretreatment, enhanced hydrolysis pretreatment, and anoxic pretreatment. Based on the organic load degradation characteristics obtained from the aforementioned tests, the system automatically selects the appropriate treatment pathway and sets the corresponding operating parameters.

[0047] Specifically, when the organic load degradation characteristics are easily degradable, a direct aerobic treatment path is selected, with a hydraulic retention time of 1.0-2.0 hours, a dissolved oxygen concentration of 1.8-2.8 mg / L, and a pH of 7.0-7.5. When the organic load degradation characteristics are difficult to degrade, a hydrolysis-acidification pretreatment path is selected, with a hydraulic retention time of 6.5-8.5 hours, a dissolved oxygen concentration below 0.08 mg / L, and a pH of 6.6-7.0. When the organic load degradation characteristics are non-aromatic and difficult to degrade, an enhanced hydrolysis pretreatment path is selected. When the organic load degradation characteristics are mixed, an anoxic pretreatment path is selected. An ammonia nitrogen analyzer is installed on the effluent pipeline of the primary pretreatment reactor to detect the ammonia nitrogen concentration in the intermediate water quality data after treatment. The ammonia nitrogen analyzer uses an online detection method with a detection interval of 10-15 minutes, enabling continuous monitoring of changes in ammonia nitrogen concentration and extraction of ammonia nitrogen conversion parameters. The secondary aerobic reactor receives intermediate water quality data from the primary pretreatment reactor and performs gradient dissolved oxygen regulation based on ammonia nitrogen conversion parameters.

[0048] See also Fig. 3The two-stage aerobic reactor employs a zoned dissolved oxygen gradient control design. The reactor is 12 meters long and is divided into three functional zones along the water flow direction: a high-load zone at the front, a transition zone in the middle, and a fine treatment zone at the rear. The high-load zone at the front is 3.6 meters long and is primarily responsible for the rapid degradation of high-concentration organic matter. A dissolved oxygen sensor is installed in this zone, with a target dissolved oxygen concentration of 3.11 mg / L. The high-load zone at the front is equipped with a large-bubble aeration device with an aerator diameter of [missing information]. The 40mm thick section provides ample oxygen supply and strong hydraulic agitation, ensuring rapid oxidation and decomposition of organic matter. The intermediate transition zone, 4.8 meters long, serves as a buffer and balance area between the high-load pretreatment and the subsequent fine treatment. A dissolved oxygen sensor is installed in this zone, with a target dissolved oxygen concentration of 2.72 mg / L. The intermediate transition zone uses rectangular aerators to provide moderate aeration intensity, primarily for balancing the carbon-to-nitrogen ratio and degrading organic matter under moderate load. The final fine treatment zone, 3.6 meters long, is responsible for the final advanced treatment and stabilization of the effluent quality. A dissolved oxygen sensor is installed in this zone, with a target dissolved oxygen concentration of 1.94 mg / L. The final fine treatment zone uses intermittent aeration or fine filtration to achieve final optimization of the effluent quality through lower dissolved oxygen concentrations and precise control. Dashed lines separate the zones, indicating adjustable boundary settings. Each zone is equipped with a monitoring point for real-time monitoring of its treatment effect and operating status. The dissolved oxygen concentration throughout the reactor exhibits a gradient distribution that gradually decreases from the front section to the rear section, i.e. This enables differentiated oxygen supply and optimal control at different treatment stages.

[0049] Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0050] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A dynamic control method applied to an aquaculture wastewater recycling system, characterized in that, Includes the following steps: Step S1: Continuously monitor the aquaculture wastewater on the inlet pipe, calculate the ratio of chemical oxygen demand to five-day biochemical oxygen demand as the first degradation indicator, and calculate the ratio of ultraviolet absorbance to total organic carbon concentration as the second degradation indicator. Step S2: Identify time-dependent and range-dependent organic load degradation characteristics based on the first and second degradation indicators, and determine the process treatment path based on the organic load degradation characteristics; Primary pretreatment of aquaculture wastewater was carried out in different process treatment paths to obtain intermediate water quality data; Step S3: Detect the ammonia nitrogen concentration in the intermediate water quality data and extract the time change rate of ammonia nitrogen concentration as an ammonia nitrogen conversion parameter; Step S4: Use ammonia nitrogen conversion parameters to perform gradient dissolved oxygen regulation on intermediate water quality data, and monitor the secondary aerobic treatment effluent data on the effluent pipeline; Step S5: Compare the effluent data from the secondary aerobic treatment with the preset target, and perform closed-loop feedback adjustment and load shock protection to achieve stable effluent that meets the standards.

2. The dynamic control method for an aquaculture wastewater recycling system according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Install an automatic sampling device on the inlet pipe. Automatically collect water samples at set intervals and send them to the chemical oxygen demand (COD) analyzer and the five-day biochemical oxygen demand (BOD) analyzer for offline testing. Calculate the ratio of COD to BOD as the first degradation indicator. Step S12: Install a total organic carbon analyzer and a 254 nm wavelength ultraviolet spectrophotometer sequentially on the aquaculture wastewater inlet pipe, and set the continuous sampling interval to 5-10 minutes; Step S13: The total organic carbon concentration of the aquaculture wastewater is continuously detected by a total organic carbon analyzer, and the ultraviolet absorbance of the aquaculture wastewater at a wavelength of 254 nm is continuously detected by a 254 nm wavelength ultraviolet spectrophotometer. Step S14: Calculate the ratio of UV absorbance value to total organic carbon concentration value as the second degradation index.

3. The dynamic control method for aquaculture wastewater recycling system according to claim 2, characterized in that, Step S2, which identifies time-complementary and range-complementary organic load degradation characteristics based on the first and second degradation indices, includes: The organic load is initially predicted by using the rapid detection characteristics of the second degradation index. When the value of the second degradation index is greater than the preset aromaticity threshold, it is predicted that there are aromatic components. When the value of the second degradation index is less than or equal to the preset aromaticity threshold, it is predicted that the content of aromatic components is low, thus determining the aromaticity characteristics. The organic load was fully verified by utilizing the full-spectrum detection characteristics of the first degradation index. When the value of the first degradation index was greater than the preset biodegradability threshold, it was verified as a difficult-to-degrade organic load. When the value of the first degradation index was less than or equal to the preset biodegradability threshold, it was verified as an easily degradable organic load, thus determining the degradation load characteristics. When the aromaticity characteristics show a low content of aromatic components and the degradation load characteristics show an easily degradable organic load, the organic load degradation characteristics are determined to be of the easily degradable type. When the aromaticity characteristics indicate the presence of recalcitrant aromatic components and the degradation load characteristics indicate a recalcitrant organic load, the organic load degradation characteristics are determined to be of the recalcitrant type. When the aromaticity characteristics show a low content of aromatic components but the degradation load characteristics show a recalcitrant organic load, the organic load degradation characteristics are determined to be of the non-aromatic recalcitrant type. When aromaticity and degradation load characteristics have other combinations, the organic load degradation characteristics are determined to be of a mixed type.

4. The dynamic control method for an aquaculture wastewater recycling system according to claim 3, characterized in that, Step S2, which determines the process path based on the degradation characteristics of organic load, includes: When the organic load degradation characteristics are easily degradable, the parameter combination is set as follows: hydraulic retention time 1.0-2.0 hours, dissolved oxygen concentration 1.8-2.8 mg / L, and hydrogen ion concentration index 7.0-7.5, which is determined as the direct aerobic treatment path; When the organic load degradation characteristics are recalcitrant, the parameter combination is set as follows: hydraulic retention time 6.5-8.5 hours, dissolved oxygen concentration less than 0.08 mg / L, and hydrogen ion concentration index 6.6-7.0, which is determined as the hydrolysis acidification pretreatment path; When the organic load degradation characteristics are non-aromatic and difficult to degrade, the parameter combination is set as follows: hydraulic retention time 5.0-7.0 hours, dissolved oxygen concentration 0.1-0.3 mg / L, and hydrogen ion concentration index 6.8-7.2, which is determined as the enhanced hydrolysis pretreatment path; When the degradation characteristics of organic load are mixed, the parameter combination is set as follows: hydraulic retention time 5.0-7.0 hours, dissolved oxygen concentration 0.1-0.3 mg / L, and hydrogen ion concentration index 6.8-7.2, which is determined as the anoxic pretreatment path; The determined processing path and corresponding parameter combination are used as the process processing path and transmitted to the control center of the primary pretreatment reactor.

5. The dynamic control method for an aquaculture wastewater recycling system according to claim 4, characterized in that, In step S2, the aquaculture wastewater is treated using a specific process, and the resulting intermediate water quality data includes: Aquaculture wastewater is introduced into a primary pretreatment reactor. The equipment combination is started and the operating parameters are set according to the process treatment path to obtain the corresponding reactor operating status. The primary pretreatment reactor, under operating conditions, performs biochemical treatment on aquaculture wastewater to adjust the hydrogen ion concentration index to the target range, thus obtaining standard hydrogen ion concentration wastewater. By installing monitoring devices in the reactors of each process path, the hydrogen ion concentration standard tailwater is monitored in real time. The direct aerobic treatment path monitors dissolved oxygen and pH value, the hydrolysis acidification pretreatment path monitors temperature and redox potential, the enhanced hydrolysis pretreatment path monitors enzyme activity and particle size, and the anoxic pretreatment path monitors dissolved oxygen change cycle and circulation flow rate, thus obtaining a real-time parameter set. Chemical oxygen demand (COD) and total organic carbon (TOC) concentrations were measured at the effluent outlet of the primary pretreatment reactor. The treatment effect was verified by combining the real-time parameter set, and intermediate water quality data were obtained.

6. The dynamic control method for an aquaculture wastewater recycling system according to claim 5, characterized in that, Step S3 includes the following steps: Step S31: Install an online ammonia nitrogen analyzer 0.5-1.0 meters away from the inlet of the secondary aerobic reactor in the inlet pipeline, set the detection interval to 10-15 minutes, continuously detect the ammonia nitrogen concentration value of intermediate water quality data, and record the timestamp of each detection to obtain a time-stamped ammonia nitrogen concentration sequence data; Step S32: When any value in the ammonia nitrogen concentration sequence data deviates from its adjacent value by more than 30%, it is marked as abnormal data; Step S33: When abnormal data is detected, the repeated detection mechanism is activated. The median of the three consecutive detections is taken as the effective value at the current moment, thus obtaining a reliable ammonia nitrogen concentration time series. Step S34: Use the ammonia nitrogen concentration time series to extract ammonia nitrogen conversion parameters and obtain graded and quantified ammonia nitrogen conversion parameters.

7. The dynamic control method for an aquaculture wastewater recycling system according to claim 6, characterized in that, Step S34 includes the following steps: A sliding time window is constructed by using a predetermined number of consecutive detection points in the ammonia nitrogen concentration time series, and the linear relationship between ammonia nitrogen concentration and time within the window is calculated. The slope of the fitted line is taken as the rate of change of ammonia nitrogen concentration during that time period. Calculate the standard deviation of the rate of change of ammonia nitrogen concentration in the past hour, and denote it as the rate of change fluctuation coefficient. When the rate of change fluctuation coefficient is less than 0.15, it is determined to be a stable trend; when the rate of change fluctuation coefficient is greater than 0.25, it is determined to be a fluctuating trend; when the rate of change fluctuation coefficient is between 0.15 and 0.25, it is determined to be a transitional trend. The trend stability is recorded. The confidence weight of the ammonia nitrogen concentration change rate is assigned based on the trend stability to obtain the trend-corrected ammonia nitrogen change rate. When the ammonia nitrogen change rate is negative and its absolute value is greater than 5 mg / L / h, it is set as a high-intensity conversion parameter; when the absolute value of the ammonia nitrogen change rate is between 2 and 5 mg / L / h, it is set as a medium-intensity conversion parameter; and when the absolute value of the ammonia nitrogen change rate is less than 2 mg / L / h, it is set as a low-intensity conversion parameter. The graded and quantified ammonia nitrogen conversion parameters are then transferred to the secondary aerobic reactor.

8. The dynamic control method for an aquaculture wastewater recycling system according to claim 7, characterized in that, Step S4 includes the following steps: Step S41: Convert the received ammonia nitrogen conversion parameters into ammonia nitrogen conversion oxygen demand coefficients, read the chemical oxygen demand (COD) value from the intermediate water quality data, and calculate the COD removal oxygen demand based on the theoretical ratio that 1.2 mg / L of dissolved oxygen is consumed to remove 1 mg / L of COD, thus obtaining the organic matter degradation oxygen demand value. Step S42: Calculate the oxygen demand for carbon oxidation based on the empirical ratio that 1 mg / L of total organic carbon requires 1.8 mg / L of dissolved oxygen, using the total organic carbon concentration value from the intermediate water quality data; Step S43: The oxygen demand coefficient for ammonia nitrogen conversion, the oxygen demand value for organic matter degradation, and the oxygen demand value for carbon oxidation are weighted and calculated to obtain the theoretical dissolved oxygen demand value. Step S44: Set the regional dissolved oxygen gradient of the secondary aerobic reactor according to the theoretical dissolved oxygen demand value to obtain the regional dissolved oxygen control scheme; Step S45: Under the control of the regional dissolved oxygen control scheme, aerobic biological treatment is carried out, and the biofilm thickness adaptive regulation mechanism is activated at the same time to obtain real-time monitoring data of the treatment process; Step S46: Pre-evaluate the treatment effect of real-time monitoring data during the treatment process, and test the effluent quality in the effluent pipeline of the secondary aerobic reactor. Compare and verify the pre-evaluation results with the actual test data to obtain the effluent data of the secondary aerobic treatment.

9. The dynamic control method for an aquaculture wastewater recycling system according to claim 8, characterized in that, Step S44 includes: Based on the theoretical dissolved oxygen demand, the reactor is divided into a high-load zone, a transition zone, and a fine treatment zone. When the demand is greater than 8 mg / L, the reactor is divided in a 4:3:3 ratio; when the demand is between 4 and 8 mg / L, it is divided in a 3:4:3 ratio; and when the demand is less than 4 mg / L, it is divided in a 2:4:4 ratio, thus obtaining the zone length configuration scheme. Based on the regional length configuration scheme, adjustable baffles are installed in the reactor, and dissolved oxygen concentration transition buffer zones are set at the boundaries of each region. The length of the buffer zone is set to 10-15% of the length of the adjacent region, resulting in a physical partition structure layout. By using alternating large and microbubbles for aeration, rapid protein decomposition aeration is carried out in the high-load zone at the front end, resulting in a dedicated aeration configuration for the front end area. In the intermediate transition zone, when the carbon-nitrogen ratio is detected to be lower than 8:1, a carbon source is automatically added; when the carbon-nitrogen ratio is higher than 15:1, the aeration intensity is increased to obtain a balanced regulation configuration in the intermediate zone. Periodic configuration is carried out in the downstream fine treatment area. During the peak period of fish water exchange, fine filtration devices and deep aeration equipment are added, and intermittent aeration mode is used during other periods to obtain the periodic adaptive configuration of the downstream area. A regional dissolved oxygen control scheme is formed based on the physical zoning structure layout and the configuration scheme of each region.

10. The dynamic control method for an aquaculture wastewater recycling system according to claim 9, characterized in that, Step S5 includes the following steps: Step S51: Compare the effluent data from the secondary aerobic treatment with the preset target to obtain the water quality compliance assessment results; Step S52: Based on the water quality compliance assessment results, perform closed-loop feedback adjustment. When the effluent indicators exceed the standards, automatically send parameter adjustment instructions to the upstream treatment unit to obtain system feedback adjustment instructions. Step S53: Monitor sudden changes in influent load and implement load shock protection. When the influent chemical oxygen demand or ammonia nitrogen concentration increases by more than 20% within 10 minutes, the protection mode is activated, automatically switching the system to high-intensity treatment state and extending the treatment time, thus entering the load shock protection state. Step S54: Achieve stable and compliant effluent under system feedback regulation and load shock protection.

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