Multi-stage physicochemical and biochemical synergistic integrated treatment process for high-salt organic wastewater

Abstract

This invention discloses a multi-stage synergistic physicochemical and biochemical integrated treatment process for high-salt organic wastewater, belonging to the field of industrial wastewater treatment technology. It selectively breaks down heavy metal complexes in wastewater through pH adjustment coupled with advanced oxidation, followed by coagulation and sedimentation to separate precipitated metal salts and macromolecular organic matter. The effluent is then introduced into a sequencing batch reactor (SBR), employing specific salt-tolerant bacteria acclimated to gradient salinity. Under gradient salinity control, the layered structure of the biofilm achieves stable degradation of organic matter in the wastewater. This invention achieves selective breakdown and coagulation separation of heavy metal complexes through pH adjustment coupled with advanced oxidation, reducing subsequent biochemical load and salt interference. The specific salt-tolerant bacteria acclimated to gradient salinity, combined with the layered biofilm structure, can stably degrade organic matter in a high-salt environment. The low-intensity catalytic oxidation unit uses residual salt in the wastewater as a catalytic medium to deeply mineralize recalcitrant organic matter under mild conditions, simultaneously achieving salt balance regulation.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to an integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy. Background Technology

[0002] High-salinity organic wastewater is widely generated in industries such as chemical, pharmaceutical, printing and dyeing, and coal chemical processing. It is characterized by high salt content, high organic matter concentration, complex composition, and poor biodegradability, making it difficult to treat. High-salinity environments significantly inhibit the activity of conventional microorganisms, leading to unstable operation of biological treatment systems. The wastewater typically contains complexed heavy metals and stable macromolecular organic matter; relying solely on physicochemical methods is insufficient for efficient complex breaking and deep degradation, resulting in high treatment costs and a high risk of secondary pollution.

[0003] Existing treatment processes mostly employ a combination of physicochemical pretreatment and conventional biochemical methods, which suffer from poor selectivity in complex breaking, long acclimatization periods for salt-tolerant microorganisms, and weak system resistance to salinity shocks. Advanced treatment units often rely on external catalysts and oxidants, failing to fully utilize the catalytic potential of inherent salts in the wastewater, resulting in high energy and reagent consumption. Furthermore, each treatment unit is mostly independently controlled, lacking a comprehensive collaborative control mechanism based on online water quality monitoring, making it difficult to cope with system disturbances caused by fluctuations in influent water quality, and thus compromising treatment effectiveness and operational stability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a multi-stage synergistic physicochemical and biochemical integrated treatment process for high-salt organic wastewater. The technical solution adopted is as follows: The integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy includes the following steps: Step 1: Selectively break down heavy metal complexes in wastewater by coupling advanced oxidation with pH adjustment, followed by separation of precipitated metal salts and macromolecular organic matter through coagulation and sedimentation. Step 2: The effluent from Step 1 is introduced into a sequencing batch reactor (SBR). Specific salt tolerance acclimated to gradient salinity is adopted. Under gradient salinity control mode, the stratified structure of the biofilm is used to achieve stable degradation of organic matter in the wastewater. Step 3: Introduce the effluent from Step 2 into a low-intensity catalytic oxidation unit. Utilize the residual salt in the wastewater as a catalytic medium to generate free radicals through electrochemical or chemical oxidation, further mineralizing the residual recalcitrant organic matter, and simultaneously adjusting the effluent salt balance. Based on online monitoring data of the influent water quality, the operating parameters at each stage are dynamically optimized through a central control system. The online monitoring data includes influent flow rate Q, chemical oxygen demand (COD), and salinity. , Complex metal concentration M.

[0005] Optionally, the method for selectively breaking down heavy metal complexes in step 1 is as follows: Based on the type and stability constant of the complexes in the wastewater, the pH is precisely adjusted to 2.5-3.5 or 10.5-11.5, and persulfate or Fenton's reagent is added; through online ORP monitoring feedback, a PID control algorithm is used to automatically adjust the oxidant dosing rate, controlling the ORP within the target range of 450-550 mV to ensure that free radicals preferentially oxidize the ligands of the complexes; the expression for the PID control algorithm is: ; in The frequency of the oxidant dosing pump, , The deviation between the ORP setpoint and the measured value. , and These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0006] Optionally, in step 1, polyferric sulfate or polyacrylamide is added to the coagulation and sedimentation process, and the insoluble inorganic salts generated by the complex-breaking reaction are removed simultaneously by controlling the sedimentation time, so as to reduce the total salt content entering the biochemical system.

[0007] Optionally, in step 2, specific salt tolerance is obtained by compound cultivation and acclimatization of marine sediment, salt field sludge and existing salt-tolerant bacteria in an environment with gradually increasing salinity. The acclimatization salinity gradient is set to 1%, 3%, 5%, and 8%, and at least two hydraulic retention times are maintained at each salinity gradient until the COD removal rate stabilizes at over 85%.

[0008] Optionally, the gradient salinity control mode in step 2 is: during the operation of the sequencing batch reactor, the salinity is controlled according to the influent salinity. With a preset gradient coefficient k, the actual salinity in the reactor is gradually increased under PLC control, and the salinity change within a single cycle is... Follow the functions below: ; Where gradient coefficient During the startup phase, the salinity shock index (I) linearly increases from 0.6 to 1.0 over 3-5 cycles. When the salinity shock index I > 1.2 is detected, the system automatically extends the set reaction time. .

[0009] Optionally, in step 2, the sequencing batch reactor is equipped with modified polyurethane sponge, and a multi-layer biofilm structure consisting of an outer layer of aerobic halophilic bacteria and an inner layer of anaerobic halophilic bacteria is formed on the surface of the packing. During a single operating cycle, intermittent aeration control is adopted, and the dissolved oxygen concentration is automatically adjusted according to the salinity gradient: the low-salinity section with salinity less than 3% is set at 2.0 mg / L, and the high-salinity section with salinity ≥ 3% is set at 2.5 mg / L-3.0 mg / L.

[0010] Optionally, the method for utilizing residual salts in wastewater as a catalytic medium in step 3 is as follows: In the electrochemical oxidation unit, a DSA electrode is used to generate active chlorine in situ at a low current density by utilizing the inherent chloride ions in the biochemically treated water; the current density J is determined based on the residual salt concentration. Dynamic optimization, the formula for dynamic optimization is: ; in For the maximum allowable current density, The salt concentration is calculated based on the conductivity of the effluent. a and b are empirical coefficients calibrated through experiments to ensure maximum current efficiency. The power supply is automatically cut off when the UV254 absorption value of the effluent is lower than the set threshold.

[0011] Optionally, another way to utilize the residual salt in the wastewater as a catalytic medium in step 3 is as follows: In the catalytic wet oxidation unit, a transition metal oxide catalyst is added, and sulfate ions in the wastewater are used as a promoter to activate persulfate and generate sulfate free radicals under the conditions of temperature 60-90℃ and pressure 0.1-0.3MPa; The reaction endpoint is determined by detecting the TOC removal rate of the effluent, and the reaction is stopped when the TOC removal rate is lower than 5%.

[0012] Optionally, in step 3, the salt balance is adjusted synchronously by: monitoring the inlet and outlet conductivity of the deep treatment unit online; when the conductivity is greater than 20 mS / cm, the bypass nanofiltration system is automatically activated for partial desalination; when the conductivity is 5 mS / cm-15 mS / cm, the catalytic properties are fully utilized to achieve waste treatment with salt.

[0013] Optionally, the central control system can dynamically optimize the pH value, oxidant dosage, salinity gradient change curve, and current density at each stage based on online monitoring data of the influent water quality. The central control system has a built-in mathematical model that automatically adjusts the PID parameters, gradient coefficient, and current density empirical coefficient according to real-time data to achieve intelligent collaborative control of the entire process.

[0014] In summary, the present invention has at least one of the following beneficial technical effects: This invention provides an integrated multi-stage physicochemical and biochemical treatment process for high-salt organic wastewater. Through pH adjustment coupled with advanced oxidation, it achieves selective removal and coagulation separation of heavy metal complexes, reducing subsequent biochemical load and salt interference. Specific salt-tolerant bacteria acclimated to gradient salinity, combined with a layered biofilm structure, can stably degrade organic matter in high-salt environments, enhancing the system's shock resistance. A low-intensity catalytic oxidation unit uses residual salt in the wastewater as a catalytic medium to deeply mineralize recalcitrant organic matter under mild conditions, simultaneously achieving salt balance regulation. The entire process relies on a central control system and online monitoring data to dynamically optimize operating parameters, improving treatment efficiency, reducing reagent and energy consumption, and ensuring stable effluent quality that meets standards. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy according to the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings.

[0017] This invention discloses an integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy.

[0018] Reference Figure 1 Example 1, a multi-stage physicochemical and biochemical synergistic integrated treatment process for high-salt organic wastewater, includes the following steps: Step 1: Selectively break down heavy metal complexes in wastewater by coupling advanced oxidation with pH adjustment, followed by separation of precipitated metal salts and macromolecular organic matter through coagulation and sedimentation. Step 2: The effluent from Step 1 is introduced into a sequencing batch reactor (SBR). Specific salt tolerance acclimated to gradient salinity is adopted. Under gradient salinity control mode, the stratified structure of the biofilm is used to achieve stable degradation of organic matter in the wastewater. Step 3: Introduce the effluent from Step 2 into a low-intensity catalytic oxidation unit. Utilize the residual salt in the wastewater as a catalytic medium to generate free radicals through electrochemical or chemical oxidation, further mineralizing the residual recalcitrant organic matter, and simultaneously adjusting the effluent salt balance. Based on online monitoring data of the influent water quality, the operating parameters at each stage are dynamically optimized through a central control system. The online monitoring data includes influent flow rate Q, chemical oxygen demand (COD), and salinity. , Complex metal concentration M.

[0019] By adopting the above technical solutions, the stable and efficient treatment of high-salinity organic wastewater is achieved through the synergistic effect of three-level units: physicochemical pretreatment, gradient salinity biochemical degradation, and low-intensity catalytic oxidation, combined with intelligent control.

[0020] pH adjustment coupled with advanced oxidation can alter the coordination environment of heavy metal complexes, destroy the complex structure, and transform heavy metal ions from the complexed state to the free state. Combined with coagulation and precipitation, it can simultaneously separate the precipitated metal salts and macromolecular organic matter, thereby reducing the toxicity of wastewater and the load on subsequent biochemical treatment.

[0021] Sequencing batch biofilm reactors employ specific salt-tolerant bacteria acclimated to gradient salinity, which can adapt to high-salt environments and maintain metabolic activity. The layered structure of the biofilm creates different dissolved oxygen and microbial environments inside and outside, enabling the stepwise degradation of different types of organic matter and improving the stability of organic matter removal.

[0022] The low-intensity catalytic oxidation unit uses the salts contained in the wastewater as the catalytic medium to generate strong oxidizing free radicals in situ through electrochemical or chemical oxidation. Under mild conditions, it can deeply mineralize residual recalcitrant organic matter and adjust the salt balance according to the salt concentration of the effluent, thus avoiding the need for large-scale addition of external catalysts.

[0023] The central control system monitors influent flow rate, chemical oxygen demand, salinity, and complex metal concentration online, and provides real-time feedback and dynamic adjustment of the operating parameters of each unit, ensuring that each treatment stage is always in a state of efficient and coordinated operation, and guaranteeing the overall process's adaptability to water quality fluctuations and the stability of treatment effect.

[0024] Example 2, the method for selectively breaking down heavy metal complexes in step 1 is as follows: Based on the type and stability constant of the complexes in the wastewater, the pH is precisely adjusted to 2.5-3.5 or 10.5-11.5, and persulfate or Fenton's reagent is added; through online ORP monitoring feedback, a PID control algorithm is used to automatically adjust the oxidant dosing rate, controlling the ORP within the target range of 450-550mV to ensure that free radicals preferentially oxidize the ligands of the complexes; the expression of the PID control algorithm is: ; in The frequency of the oxidant dosing pump, , The deviation between the ORP setpoint and the measured value. , and These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0025] In Example 3, polyferric sulfate or polyacrylamide is added during the coagulation and sedimentation process in step 1, and the insoluble inorganic salts generated by the complex-breaking reaction are removed simultaneously by controlling the sedimentation time, so as to reduce the total salt content entering the biochemical system.

[0026] Example 4: In step 2, the specific salt tolerance was obtained by compounding and acclimatizing marine sediment, salt field sludge and existing salt-tolerant bacteria in an environment with gradually increasing salinity. The acclimatization salinity gradient was set to 1%, 3%, 5% and 8%, and at least two hydraulic retention times were maintained at each salinity gradient until the COD removal rate stabilized at more than 85%.

[0027] By employing the above technical solutions, the pH value of wastewater is precisely adjusted to alter the form of heavy metal complexes, thus weakening the stability of the complex bonds. Adding persulfate or Fenton's reagent generates strong oxidizing free radicals in the water. Within a set ORP range, these free radicals preferentially attack and destroy the complex ligands, causing the heavy metals to transform from a stable complexed state to a free state. The PID control algorithm adjusts the operating frequency of the oxidant dosing pump in real time based on the deviation between the ORP setpoint and the measured value, achieving precise automatic control of the oxidant dosage and ensuring the continuous and stable progress of the complex-breaking reaction.

[0028] After the complex-breaking reaction, free heavy metal ions combine with inorganic ions to form insoluble inorganic salts. Adding polyferric sulfate or polyacrylamide can enhance the aggregation effect of colloids and suspended solids, simultaneously adsorbing and entraining metal salts and large organic molecules during precipitation. By rationally controlling the precipitation time, insoluble salts and pollutants can be fully separated and settled, reducing the inorganic salt content entering the biochemical system and mitigating the inhibitory effect of high salt on microorganisms.

[0029] Based on naturally occurring halophilic microorganisms in marine sediments and salt field sludge, co-culture with artificially selected salt-tolerant strains is carried out in an environment with gradually increasing salinity to achieve targeted acclimatization. The progressively increasing salinity environment allows for the selection and retention of dominant bacterial groups that still possess metabolic activity under high salinity conditions. Extending the residence time at each gradient enhances the adaptability of the bacterial groups to high salinity environments, enabling the acclimatized microorganisms to maintain a stable organic matter degradation capacity under high salinity conditions, ensuring that COD removal efficiency consistently meets standards.

[0030] Example 5, the gradient salinity control mode in step 2 is: during the operation of the sequencing batch reactor, the salinity is controlled according to the influent salinity. With a preset gradient coefficient k, the actual salinity in the reactor is gradually increased under PLC control, and the salinity change within a single cycle is... Follow the functions below: ; Where gradient coefficient During the startup phase, the salinity shock index (I) linearly increases from 0.6 to 1.0 over 3-5 cycles. When the salinity shock index I > 1.2 is detected, the system automatically extends the set reaction time. .

[0031] In Example 6, the sequencing batch reactor in step 2 is equipped with modified polyurethane sponge, and a multi-layer biofilm structure consisting of an outer layer of aerobic halophilic bacteria and an inner layer of anaerobic halophilic bacteria is formed on the surface of the packing. During a single operating cycle, intermittent aeration control is adopted, and the dissolved oxygen concentration is automatically adjusted according to the salinity gradient: the low-salinity section with salinity less than 3% is set at 2.0 mg / L, and the high-salinity section with salinity ≥ 3% is set at 2.5 mg / L-3.0 mg / L.

[0032] By adopting the above technical solution, during the operation of the sequencing batch reactor (SBR), the actual salinity inside the reactor is gradually increased by a PLC control system based on the influent salinity and a preset gradient coefficient. The salinity change within a single cycle follows a set function. During the start-up phase, the gradient coefficient increases linearly, allowing microorganisms to gradually adapt to salinity changes and avoiding shocks to microbial activity caused by sudden salinity fluctuations. A salinity shock index is used to determine the degree of influent salinity fluctuation. When the index exceeds a set threshold, the system automatically extends the reaction time, providing sufficient time for microorganisms to adapt and metabolize, ensuring stable reactor operation and maintaining organic matter degradation efficiency.

[0033] The modified polyurethane sponge built into the sequencing batch reactor (SBR) provides a stable carrier for microbial attachment, facilitating the formation of a stratified biofilm structure. The outer layer of aerobic halophilic bacteria degrades readily degradable organic matter in an aerobic environment, while the inner layer of anaerobic halophilic bacteria degrades recalcitrant organic matter, achieving efficient stepwise degradation of different types of organic matter. Intermittent aeration control combined with dynamic adjustment of dissolved oxygen concentration using salinity gradients maintains lower dissolved oxygen levels in low-salt sections to meet the metabolic needs of microorganisms, while increasing dissolved oxygen concentration in high-salt sections alleviates the inhibitory effect of high-salt environments on microbial activity, ensuring the metabolic efficiency of the biofilm community and the stability of the system.

[0034] Example 7, the method of using residual salt in wastewater as a catalytic medium in step 3 is as follows: In the electrochemical oxidation unit, a DSA electrode is used to generate active chlorine in situ at a low current density by utilizing the chloride ions inherent in the biochemically treated water; the current density J is based on the residual salt concentration. Dynamic optimization, the formula for dynamic optimization is: ; in For the maximum allowable current density, The salt concentration is calculated based on the conductivity of the effluent. a and b are empirical coefficients calibrated through experiments to ensure maximum current efficiency. The power supply is automatically cut off when the UV254 absorption value of the effluent is lower than the set threshold.

[0035] By adopting the above technical solution, the electrochemical oxidation unit uses a DSA electrode, utilizing the chloride ions naturally present in the biochemical effluent as a catalytic medium. Under low current density conditions, chloride ions undergo an electrochemical reaction on the electrode surface to generate active chlorine in situ. Active chlorine has strong oxidizing properties and can efficiently mineralize residual recalcitrant organic matter in wastewater. The current density is dynamically optimized based on the residual salt concentration calculated from the effluent conductivity, adjusted according to a set formula, taking into account the correlation between the maximum allowable current density and salt concentration. An empirical coefficient calibrated through experiments ensures that the current efficiency is at its optimal level. The UV254 absorbance value of the effluent is used to determine the degree of mineralization of recalcitrant organic matter. When this value is below a set threshold, it indicates that the organic matter has been fully degraded, and the system automatically cuts off the power supply, achieving energy-saving and efficient operation of the process.

[0036] Example 8, another way to utilize the residual salt in wastewater as a catalytic medium in step 3 is as follows: In the catalytic wet oxidation unit, a transition metal oxide catalyst is added, and sulfate ions in the wastewater are used as a promoter to activate persulfate and generate sulfate free radicals under the conditions of temperature 60-90℃ and pressure 0.1-0.3MPa; The reaction endpoint is determined by detecting the TOC removal rate of the effluent, and the reaction is stopped when the TOC removal rate is lower than 5%.

[0037] By adopting the above technical solution, in the catalytic wet oxidation unit, the transition metal oxide catalyst can effectively activate persulfate, and the sulfate ions present in the wastewater can further enhance the activation process, continuously generating highly oxidizing sulfate free radicals under set temperature and pressure conditions. These sulfate free radicals can rapidly attack and mineralize residual recalcitrant organic matter in the wastewater, improving effluent quality. The reaction progress is judged by real-time monitoring of the effluent TOC removal rate. When the removal rate falls below a set value, it indicates that the degradable organic matter has been essentially completely treated, at which point the reaction is stopped. This ensures treatment effectiveness while reducing energy and reagent consumption, improving the economic efficiency of the process operation.

[0038] In Example 9, the synchronous adjustment of salt balance in step 3 is as follows: by monitoring the inlet and outlet conductivity of the deep treatment unit online, when the conductivity is greater than 20 mS / cm, the bypass nanofiltration system is automatically turned on for partial desalination; when the conductivity is 5 mS / cm-15 mS / cm, the catalytic properties are fully utilized to achieve waste treatment with salt.

[0039] By adopting the above technical solution, conductivity can directly reflect the salt concentration in wastewater. Online monitoring of the inlet and outlet conductivity of the deep treatment unit allows for real-time monitoring of changes in effluent salt content. When the conductivity exceeds a set threshold, it indicates excessively high effluent salt concentration. In this case, the bypass nanofiltration system is automatically activated for partial desalination, reducing the effluent salinity to a reasonable range and ensuring effluent compliance. When the conductivity is within a suitable range, no additional desalination treatment is required. The catalytic effect of residual salt in the wastewater is fully utilized to continuously enhance the mineralization process of recalcitrant organic matter, achieving the goal of treating waste with salt. This ensures stable salt balance, improves process efficiency, and reduces treatment costs.

[0040] Example 10: The central control system dynamically optimizes the pH value, oxidant dosage, salinity gradient change curve, and current density at each stage based on online monitoring data of the influent water quality. The central control system has a built-in mathematical model that automatically adjusts the PID parameters, gradient coefficient, and current density empirical coefficient according to real-time data to achieve intelligent collaborative control of the entire process.

[0041] By adopting the above technical solutions, the central control system consists of an online monitoring module, a data processing module, a model calculation module, an execution control module, and a feedback adjustment module. All modules work together to achieve intelligent collaborative control of the entire process. The core relies on the online monitoring data of the influent water quality to carry out dynamic optimization of various parameters, ensuring that the operating efficiency and treatment effect of each treatment stage reach the optimal level.

[0042] The online monitoring module collects key water quality parameters in real time, including influent flow rate, chemical oxygen demand (COD), salinity, and complex metal concentration. The monitoring frequency is set to once every 10 minutes. The collected data is preprocessed and then transmitted to the data processing module to remove outliers and supplement missing data, forming a standardized real-time water quality dataset. This provides a precise and reliable basis for subsequent parameter optimization. Specifically, COD is detected online using potassium dichromate, salinity is obtained through conductivity conversion, and complex metal concentration is detected online using spectrophotometry.

[0043] Based on real-time water quality data after pretreatment, the central control system dynamically optimizes the core operating parameters of each treatment stage. For the pH adjustment and advanced oxidation process in step 1, the system automatically adjusts the pH adjustment range according to the concentration of complexed metals and chemical oxygen demand (COD) values ​​to ensure that the pH is accurately maintained within the set range. At the same time, it dynamically adjusts the oxidant dosage to match the concentration of pollutants in the wastewater, avoiding waste caused by excessive oxidant or incomplete complex breaking due to insufficient dosage.

[0044] For the sequencing batch reactor (SBR) operation in step 2, the system dynamically optimizes the salinity gradient curve based on influent salinity data, adjusting the gradient ramp rate and the duration of each gradient to ensure that salinity changes within the reactor are consistent with the adaptation rhythm of the specific salt-tolerant bacterial community. Simultaneously, the hydraulic retention time of the reactor is adjusted to guarantee the degradation efficiency of organic matter by the bacteria. For the low-intensity catalytic oxidation unit in step 3, the system dynamically optimizes the current density based on the salt concentration data of the biochemical effluent to ensure efficient catalytic oxidation while avoiding energy waste caused by excessively high current densities.

[0045] The central control system incorporates multiple dedicated mathematical models, including a water quality prediction model, a parameter optimization model, and a feedback control model. These models work together to achieve automatic parameter correction and optimization. Specifically, the water quality prediction model predicts the effluent quality of each treatment unit based on real-time influent water quality data, providing a predictive basis for parameter optimization. The parameter optimization model automatically adjusts PID control parameters, salinity gradient coefficient, and current density empirical coefficient based on the prediction results and actual operating data.

[0046] Regarding PID control parameter adjustment, the system automatically corrects the proportional, integral, and derivative coefficients based on the deviation between online ORP monitoring data and the set target value, optimizing the operating frequency of the oxidant dosing pump to ensure that the ORP remains stable within the target range of 450-550mV, guaranteeing the stability and thoroughness of the complex-breaking reaction. As for salinity gradient coefficient adjustment, the system automatically corrects the linear growth rate and stable value of the gradient coefficient based on influent salinity fluctuations. During startup, it ensures that the gradient coefficient increases linearly from 0.6 to 1.0 within 3-5 cycles. When an abnormal salinity shock index is detected, the gradient coefficient and reaction time are adjusted simultaneously to mitigate the impact of salinity shock on the biological system.

[0047] Regarding the adjustment of the empirical coefficients for current density, the system automatically updates the empirical coefficients a and b based on the salt concentration calculated from the conductivity of the biochemical effluent using a built-in model, ensuring that the current density always follows the established parameters. The optimized formula balances current efficiency and energy consumption control. When the UV254 absorption value of the effluent is lower than the set threshold, the power supply is automatically cut off to achieve energy-saving operation.

[0048] The execution control module transforms the optimized parameters calculated by the model into specific control commands, which are then transmitted to the actuators of each treatment unit, including pH adjustment pumps, oxidant dosing pumps, PLC controllers, aeration equipment, nanofiltration systems, and electrode power supplies, to achieve precise execution of the operating parameters of each unit. The feedback adjustment module collects effluent water quality data and operating status data from each treatment unit in real time and compares them with the set standards. If parameter deviations or substandard water quality occur, feedback is immediately sent to the data processing module and the model calculation module to re-optimize parameters and adjust commands, forming a closed-loop control.

[0049] The following specific embodiments illustrate the implementation principle of the present invention: For high-salt organic wastewater generated by the chemical industry, a multi-stage physicochemical-biological integrated treatment process is adopted to achieve efficient treatment and compliant discharge of wastewater. The specific implementation process is as follows: The influent water quality of the high-salt organic wastewater to be treated is as follows: chemical oxygen demand (COD) concentration of 3500-4200 mg / L, salinity of 4%-7%, complex metal concentration of 120-180 mg / L, and influent flow rate of 8-12 m³ / h. The specific steps for treatment using this process are as follows: Step 1, pH adjustment coupled with advanced oxidation and coagulation sedimentation: First, based on the types and stability constants of complexes in the wastewater, the pH is precisely adjusted to 2.5-3.5. Persulfate is added as an oxidant. Through online ORP monitoring feedback, a PID control algorithm is used to automatically adjust the oxidant dosing rate, controlling the ORP to remain stable within the 450-550mV range, selectively breaking down heavy metal complexes in the wastewater. After the complex-breaking reaction is complete, polyferric sulfate is added to the wastewater, controlling the sedimentation time, simultaneously separating the precipitated metal salts and macromolecular organic matter, reducing wastewater toxicity and the load on subsequent biological treatment. The effluent salinity is reduced to 3%-5%, and the chemical oxygen demand removal rate reaches 40%-50%.

[0050] Step 2, Biochemical Degradation Treatment by Sequencing Batch Reactor (SBR): The effluent from Step 1 is introduced into a SBR. The reactor contains modified polyurethane sponge packing material, forming a multi-layered biofilm structure on the packing surface consisting of an outer layer of aerobic halophilic bacteria and an inner layer of anaerobic halophilic bacteria. The specific halophilic bacterial community used in the reactor is obtained through co-cultivation and directed acclimation of marine sediment, salt field sludge, and existing halophilic bacterial strains under gradually increasing salinity. The acclimation salinity gradient is set sequentially to 1%, 3%, 5%, and 8%, with each salinity gradient maintained for at least two hydraulic retention times until the COD removal rate stabilizes above 85%.

[0051] The reactor operates using a gradient salinity control mode. Based on the influent salinity and a preset gradient coefficient, the actual salinity within the reactor is gradually increased via PLC control. Salinity changes within a single cycle follow a set function. During the start-up phase, the gradient coefficient linearly increases from 0.6 to 1.0 over 3-5 cycles. When the salinity shock index exceeds 1.2, the system automatically extends the reaction time. Intermittent aeration is used within a single operating cycle. The dissolved oxygen concentration is automatically adjusted according to the salinity gradient: 2.0 mg / L for low-salinity sections (less than 3%) and 2.5-3.0 mg / L for high-salinity sections (not less than 3%). Stable degradation of organic matter in the wastewater is achieved through a biofilm stratified structure. In this step, the effluent chemical oxygen demand (COD) is reduced to 350-450 mg / L, and the COD removal rate remains stable above 85%.

[0052] Step 3, Low-intensity catalytic oxidation and salt balance adjustment: The effluent from Step 2 is introduced into a low-intensity catalytic oxidation unit, with two implementation methods available. Method 1 is electrochemical oxidation, using a DSA electrode. It utilizes the inherent chloride ions in the biochemical effluent to generate active chlorine in situ at a low current density. The current density is dynamically optimized based on the residual salt concentration calculated from the effluent conductivity, adjusted according to a set formula. The power is automatically cut off when the UV254 absorbance of the effluent falls below a set threshold. Method 2 is catalytic wet oxidation, adding a transition metal oxide catalyst. It utilizes sulfate ions in the wastewater as a promoter, activating persulfate to generate sulfate free radicals under conditions of 60-90℃ and 0.1-0.3MPa. The reaction endpoint is determined by detecting the TOC removal rate of the effluent; the reaction is stopped when the TOC removal rate falls below 5%.

[0053] During the treatment process, the salt balance is simultaneously adjusted. The inlet and outlet conductivity of the deep treatment unit is monitored online. When the conductivity exceeds 20 mS / cm, the bypass nanofiltration system is automatically activated for partial desalination. When the conductivity is between 5 and 15 mS / cm, the catalytic properties are fully utilized to treat wastewater with salt. After this step, the recalcitrant organic matter in the wastewater is deeply mineralized, the effluent chemical oxygen demand is reduced to below 50 mg / L, the salinity is controlled between 5 and 15 mS / cm, and the heavy metal concentration meets the standards for industrial wastewater discharge.

[0054] Throughout the treatment process, the central control system dynamically optimizes the operating parameters at each stage based on online monitoring data of the influent water quality. This online monitoring data includes influent flow rate, chemical oxygen demand (COD), salinity, and complex metal concentration, with a monitoring frequency set to once every 10 minutes. The central control system consists of an online monitoring module, a data processing module, a model calculation module, an execution control module, and a feedback adjustment module. It incorporates a dedicated mathematical model and automatically adjusts PID parameters, gradient coefficients, and empirical current density coefficients based on real-time data, achieving intelligent and coordinated control across the entire process. This ensures efficient linkage between treatment units, responds to fluctuations in influent water quality, and guarantees stable treatment results.

[0055] The core technical performance indicators of the process of this invention were compared with those of traditional high-salt organic wastewater treatment processes. The comparison conditions were based on the same influent water quality (COD 3500-4200 mg / L, salinity 4%-7%, complex metal concentration 120-180 mg / L), the same treatment scale, and the same operating conditions. The specific comparison results are shown in Table 1. Table 1

[0056] In summary, under the same influent water quality, treatment scale, and operating conditions, the process of this invention demonstrates significant advantages over traditional treatment processes in core technical performance indicators such as COD removal, heavy metal removal, salinity control, and mineralization of recalcitrant organic matter. Through multi-stage physicochemical and biochemical synergy and intelligent full-process control, this invention achieves highly efficient and stable treatment of high-salinity organic wastewater. It not only significantly improves pollutant removal efficiency and effluent compliance stability but also reduces sludge production and treatment costs, broadens the process's applicability, and effectively solves the technical pain points of traditional processes for treating high-salinity organic wastewater, such as poor treatment effect, unstable operation, and narrow applicability. It possesses significant technical superiority and practical application value.

[0057] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater, characterized in that, Includes the following steps: Step 1: Selectively break down heavy metal complexes in wastewater by coupling advanced oxidation with pH adjustment, followed by separation of precipitated metal salts and macromolecular organic matter through coagulation and sedimentation. Step 2: The effluent from Step 1 is introduced into a sequencing batch reactor (SBR). Specific salt tolerance acclimated to gradient salinity is adopted. Under gradient salinity control mode, the stratified structure of the biofilm is used to achieve stable degradation of organic matter in the wastewater. Step 3: Introduce the effluent from Step 2 into a low-intensity catalytic oxidation unit. Utilize the residual salt in the wastewater as a catalytic medium to generate free radicals through electrochemical or chemical oxidation, further mineralizing the residual recalcitrant organic matter, and simultaneously adjusting the effluent salt balance. Based on online monitoring data of the influent water quality, the operating parameters at each stage are dynamically optimized through a central control system. The online monitoring data includes influent flow rate Q, chemical oxygen demand (COD), and salinity. , Complex metal concentration M.

2. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 1, characterized in that, The method for selectively breaking down heavy metal complexes in step 1 is as follows: Based on the type and stability constant of the complexes in the wastewater, the pH is precisely adjusted to 2.5-3.5 or 10.5-11.5, and persulfate or Fenton's reagent is added; through online ORP monitoring feedback, a PID control algorithm is used to automatically adjust the oxidant dosing rate, controlling the ORP within the target range of 450-550mV to ensure that free radicals preferentially oxidize the ligands of the complexes; the expression for the PID control algorithm is: ； in The frequency of the oxidant dosing pump, , The deviation between the ORP setpoint and the measured value. , and These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

3. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 2, characterized in that, In step 1, polyferric sulfate or polyacrylamide is added during the coagulation and sedimentation process. By controlling the sedimentation time, the insoluble inorganic salts generated by the complex-breaking reaction are removed simultaneously to reduce the total salt content entering the biochemical system.

4. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 3, characterized in that, In step 2, specific salt tolerance is obtained by compound cultivation and acclimatization of marine sediment, salt field sludge and existing salt-tolerant bacteria in an environment with gradually increasing salinity. The acclimatization salinity gradient is set to 1%, 3%, 5% and 8%, and at least two hydraulic retention times are maintained at each salinity gradient until the COD removal rate stabilizes at over 85%.

5. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 4, characterized in that, The gradient salinity control mode in step 2 is as follows: during the operation of the sequencing batch reactor (SBR), the salinity is controlled according to the influent salinity. With a preset gradient coefficient k, the actual salinity in the reactor is gradually increased under PLC control, and the salinity change within a single cycle is... Follow the functions below: ； Where gradient coefficient During the startup phase, the salinity shock index (I) linearly increases from 0.6 to 1.0 over 3-5 cycles. When the salinity shock index I > 1.2 is detected, the system automatically extends the set reaction time. .

6. The integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy as described in claim 5, characterized in that, In step 2, the sequencing batch reactor (SBR) incorporates modified polyurethane sponge, forming a multi-layered biofilm structure on the packing surface consisting of an outer layer of aerobic halophilic bacteria and an inner layer of anaerobic halophilic bacteria. During a single operating cycle, intermittent aeration is used for control, and the dissolved oxygen concentration is automatically adjusted according to the salinity gradient: 2.0 mg / L for the low-salinity range (salinity less than 3%) and 2.5 mg / L-3.0 mg / L for the high-salinity range (salinity ≥ 3%).

7. The integrated treatment process for high-salt organic wastewater with multi-stage physicochemical and biochemical synergy as described in claim 6, characterized in that, The method of using residual salt in wastewater as a catalyst in step 3 is as follows: In the electrochemical oxidation unit, a DSA electrode is used to generate active chlorine in situ at a low current density by utilizing the chloride ions inherent in the biochemically effluent. Current density J depends on residual salt concentration Dynamic optimization, the formula for dynamic optimization is: ; in For the maximum allowable current density, The salt concentration is calculated based on the conductivity of the effluent. a and b are empirical coefficients calibrated through experiments to ensure maximum current efficiency. The power supply is automatically cut off when the UV254 absorption value of the effluent is lower than the set threshold.

8. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 7, characterized in that, Another way to utilize the residual salt in wastewater as a catalytic medium in step 3 is as follows: In the catalytic wet oxidation unit, a transition metal oxide catalyst is added, and sulfate ions in the wastewater are used as a promoter to activate persulfate and generate sulfate free radicals under the conditions of temperature 60-90℃ and pressure 0.1-0.3MPa. The reaction endpoint is determined by detecting the TOC removal rate of the effluent. When the TOC removal rate is lower than 5%, the reaction is stopped.

9. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 8, characterized in that, In step 3, the salt balance is adjusted synchronously by monitoring the inlet and outlet conductivity of the deep treatment unit online. When the conductivity is greater than 20 mS / cm, the bypass nanofiltration system is automatically activated for partial desalination. When the conductivity is between 5 mS / cm and 15 mS / cm, the catalytic properties are fully utilized to achieve waste treatment with salt.

10. The multi-stage physicochemical-biochemical synergistic integrated treatment process for high-salt organic wastewater according to claim 9, characterized in that, The central control system dynamically optimizes the pH value, oxidant dosage, salinity gradient change curve, and current density at each stage based on online monitoring data of the influent water quality. The central control system has a built-in mathematical model that automatically adjusts the PID parameters, gradient coefficient, and current density empirical coefficient according to real-time data, thereby achieving intelligent collaborative control of the entire process.

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