High-salt oily wastewater grading composite treatment method

Abstract

The application discloses a high-salinity oil-containing wastewater grading composite treatment method, which automatically controls and adjusts the dilution of the return water of a regulating tank and starts and stops an oil removal device according to the salinity and oil content of the influent; when the liquid level and the conductivity meet preset values, the wastewater is delivered to a high-salt-tolerant biochemical treatment unit to sequentially operate in batches, the aeration amount and the alkali dosage are monitored and dynamically adjusted in real time, and when the effluent organic matter and ammonia nitrogen are lower than first and second target values respectively, the effluent is delivered to an electrochemical advanced oxidation unit. After the electrochemical unit meets the starting conditions, the treatment is performed according to the target current density and the hydraulic retention time, and the operation is optimized in combination with the organic matter concentration and energy consumption data of the influent and effluent, and the current round of treatment is ended when the effluent organic matter concentration is lower than a third target value. The method realizes the deep removal of organic pollutants in high-salinity oil-containing wastewater and stable discharge / reuse by grading connection of high-salt-tolerant biochemistry and intelligent electrochemistry, and has the advantages of high treatment efficiency, good operation stability and remarkable energy saving and consumption reduction effect.

Description

Technical Field

[0001] This application belongs to the field of industrial wastewater deep treatment and reuse technology, specifically a graded composite treatment method for high-salt and oily wastewater. Background Technology

[0002] Currently, specialized industrial sectors such as DC high-voltage converter stations commonly generate large quantities of high-salt organic wastewater. This type of wastewater is produced during equipment cooling, insulation cleaning, and factory operations, presenting multiple challenges including high salt and organic loads, complex composition, and high toxicity. The wastewater typically contains large amounts of inorganic salts such as NaCl and CaCl2, with salinity reaching 2-10%. Simultaneously, due to the widespread use of lubricating oils, conductive agents, surfactants, and cleaning agents, its chemical oxygen demand (COD) is generally high, and a large proportion of the organic pollutants are small molecules and complex organic compounds that are difficult to degrade using conventional biological methods. Furthermore, some wastewater also contains trace amounts of heavy metals and highly toxic organic substances, further increasing the difficulty of treatment.

[0003] In existing technologies, traditional physicochemical methods for high-salt environments mainly include coagulation and sedimentation, membrane filtration, adsorption, and ion exchange. These methods are relatively effective for removing inorganic salts, but their efficiency is limited when dealing with colloids, suspended solids, and high concentrations of organic matter. In particular, membrane technology is costly and prone to fouling and clogging. Biochemical methods, as the mainstay of conventional wastewater treatment, such as activated sludge processes, sequencing batch reactors (SBRs), and membrane bioreactors (MBRs), face inherent challenges in high-salt environments, including impaired microbial activity, long salt tolerance acclimation periods, and the presence of many recalcitrant components. Furthermore, for recalcitrant organic pollutants in industrial applications, advanced oxidation methods (such as ozone, Fenton, and electrochemical oxidation as secondary treatments) are commonly used. While these methods have a strong removal capacity for recalcitrant components, they rely on high energy consumption, significant catalyst depletion, or substantial operating costs. Moreover, single processes often cannot simultaneously and efficiently reduce all organic and inorganic pollutants, leading to unstable overall treatment effects, high compliance risks, and significant secondary pollution pressure in industrial settings. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this application provides a graded and composite treatment method for high-salt oily wastewater. Through the intelligent dilution and oil removal control of the pretreatment unit, the online optimized operation of the high-salt-tolerant biochemical reaction unit, and the synergistic effect of the fine and deep treatment of the electrochemical advanced oxidation unit, the method achieves efficient removal of organic pollutants from high-salt oily wastewater and stable compliance for reuse / discharge.

[0005] To achieve the above objectives, this application adopts the following technical solution: a graded and composite treatment method for high-salt and oily wastewater, applied to a graded and composite treatment system for high-salt and oily wastewater. The system includes a pretreatment unit, an equalization tank, a high-salt-tolerant biochemical treatment unit, an electrochemical advanced oxidation unit, and a central control device connected in sequence. The pretreatment unit is equipped with an online detection device for detecting the salinity and oil content of the influent; the equalization tank is equipped with a liquid level and conductivity detection device; the high-salt-tolerant biochemical treatment unit is equipped with dissolved oxygen, pH, and organic matter concentration detection devices; the electrochemical advanced oxidation unit is equipped with a current regulating device and an organic matter concentration detection device; the central control device is electrically connected to the above-mentioned detection devices and actuators. The method includes the following steps:

[0006] Acquire the influent water quality data of the pretreatment unit. When the salinity and / or oil content are higher than the preset threshold, control the addition of recycled water to the equalization tank for dilution and control the operation of the oil removal device of the pretreatment unit.

[0007] The system acquires data on liquid level and conductivity in the equalization tank. When the liquid level is within the set range and the conductivity is within the target range, the system controls the opening of the inlet valve of the high salt tolerance biological treatment unit, allowing wastewater from the equalization tank to enter the high salt tolerance biological treatment unit.

[0008] The high salt tolerance biological treatment unit is controlled to sequentially execute the steps of water influent, aeration reaction, sedimentation and drainage in a batch manner. During the aeration reaction stage, the aeration rate and alkali dosage are automatically adjusted according to the changes in dissolved oxygen, pH and organic matter concentration in the effluent. When the organic matter concentration in the effluent of the high salt tolerance biological treatment unit is detected to be lower than the first target value and the ammonia nitrogen concentration is lower than the second target value, the current batch cycle is ended and the effluent is transported to the electrochemical advanced oxidation unit.

[0009] Organic matter concentration, conductivity and flow rate are collected at the inlet of the electrochemical advanced oxidation unit. When the above parameters meet the preset start-up conditions, the electrolysis power supply is turned on and electrochemical treatment is carried out according to the initial target current density and preset hydraulic residence time.

[0010] During the operation of the electrochemical advanced oxidation unit, data on the concentration of organic matter in the influent and effluent and energy consumption are collected. When the concentration of organic matter in the effluent of the electrochemical advanced oxidation unit is detected to be lower than the third target value, the current round of electrochemical treatment is terminated and the effluent is discharged to the subsequent reuse or compliant discharge unit.

[0011] In the above steps, the central control device comprehensively adjusts the effluent flow rate of the equalization tank, the sequential batch operation cycle of the high-salt-tolerant biological treatment unit, and the operating time of the electrochemical advanced oxidation unit based on the water quality and quantity of the influent and effluent of the equalization tank and the energy consumption of each unit, so that the total chemical oxygen demand removal rate of the system meets the following requirements:

[0012] ;

[0013] in, The chemical oxygen demand (COD) concentration of the system influent. The chemical oxygen demand (COD) concentration of the overall effluent after treatment by the pretreatment unit, the high salt tolerance biological treatment unit, and the electrochemical advanced oxidation unit. Based on the influent chemical oxygen demand concentration With overall effluent chemical oxygen demand concentration The calculated total chemical oxygen demand removal rate, The target value for total chemical oxygen demand (COD) removal rate;

[0014] And keep the energy consumption per unit of COD removal within the target range.

[0015] The central control unit, while controlling the operation of the high salt tolerance biochemical treatment unit, is also used to execute an adaptive microbial community reconstruction step based on multi-omics data. This adaptive microbial community reconstruction step includes:

[0016] Metagenomic or 16S high-throughput sequencing data and metabolic fingerprint data of sludge samples from high-salt-tolerant biochemical treatment units were periodically collected to construct a mapping model between microbial community structure and treatment performance.

[0017] By correlating the microbial community structure data with online data from the high-salt-tolerant biochemical treatment unit, including dissolved oxygen, conductivity, pH, ATP content, and chemical oxygen demand removal rate, the extent to which the current microbial community composition affects the treatment effect of high-salt oily wastewater can be obtained.

[0018] When the mapping model determines that the proportion of core salt-tolerant functional bacteria is lower than the target proportion or the treatment performance of the high salt-tolerant biochemical treatment unit is lower than the preset performance threshold, the high salt-tolerant biochemical treatment unit is controlled to adjust the sludge discharge, return sludge ratio and supplementary bacterial agent dosage so that the relative abundance of core salt-tolerant functional bacteria can be restored to the target range.

[0019] The adaptive microbial community reconstruction control step also includes a microbial agent dosage adjustment step, including:

[0020] A target microbial community composition including multiple salt-tolerant degradation bacteria was defined, and the actual microbial community composition of the high salt-tolerant biochemical treatment unit was periodically tested and compared with the target microbial community composition.

[0021] When the proportion of one or more target salt-tolerant functional bacteria is detected to be lower than the corresponding preset lower limit, the central control device determines the bacterial agent addition level according to the deviation and controls the bacterial agent addition device to intermittently add the corresponding bacterial agent to the inlet section of the high salt-tolerant biochemical treatment unit.

[0022] After the microbial agent is added, monitor the changes in the composition of the microbial community and the treatment effect. If the proportion of the target salt-tolerant functional bacteria and the treatment effect reach the preset range, gradually reduce the frequency of microbial agent addition until it is stopped.

[0023] The central control unit, during the operation of the electrochemical advanced oxidation unit, executes a backfeedback dynamic optimization control step, including:

[0024] The system collects operational data from the electrochemical advanced oxidation unit, including influent and effluent organic matter concentrations, voltage, current, and energy consumption. Based on a pre-established process performance evaluation model, it calculates the organic matter removal efficiency and unit energy consumption under the current operating conditions.

[0025] In addition, electrode status data including cumulative electrode operating time, cumulative water treatment volume and changes in polarization characteristics are collected, and electrode health indicators are obtained based on the electrode degradation assessment model.

[0026] A comprehensive evaluation function is constructed with organic matter removal rate, unit energy consumption, and electrode degradation cost as optimization objectives:

[0027] ;

[0028] in, The organic matter removal rate of the electrochemical advanced oxidation unit is calculated and determined based on the organic matter concentration in the influent and the organic matter concentration in the effluent of the electrochemical advanced oxidation unit. The specific energy consumption per unit of organic matter removed is calculated based on the electrical energy consumed to remove a unit mass of organic matter in an electrochemical advanced oxidation unit. The equivalent cost index, which characterizes the degree of electrode degradation under current operating conditions, is determined based on the deviation between the electrode health index H and the target health range. , , These are weighting coefficients corresponding to organic matter removal rate, specific energy consumption, and electrode degradation cost, respectively, used to characterize the relative importance among different optimization objectives;

[0029] By predicting and evaluating different combinations of current density, polarity switching cycle, and hydraulic residence time, the combination that minimizes the comprehensive evaluation function is selected as the target operating condition, and the current density, polarity switching cycle, and operating time of the electrochemical advanced oxidation unit are adjusted accordingly.

[0030] Among them, when the central control device controls the operation of the electrochemical advanced oxidation unit, it performs a reverse feedthrough dynamic optimization control step, including: the electrode degradation cost is determined based on the deviation between the electrode health index and the target health range. When the health is lower than the preset lower limit, the central control device increases the weight of the electrode degradation cost in the comprehensive evaluation function to suppress the selection of high current density and long operating time conditions, thereby extending the electrode service life.

[0031] The central control unit employs a predictive control strategy for overall process optimization when coordinating the control and regulation tank, the high-salt-tolerant biochemical treatment unit, and the electrochemical advanced oxidation unit. This predictive control strategy includes:

[0032] Continuous online monitoring includes key state parameters such as the level of the equalization tank, the concentration of organic matter in the biological effluent, and the concentration of organic matter in the electrochemical effluent.

[0033] The historical changes and current trends of influent water quality and quantity are used as disturbance inputs to predict the load of each unit in the future period.

[0034] Based on the prediction results, feedforward adjustments were made to the effluent flow rate of the equalization tank, the batch operation cycle of the high salt tolerance biological treatment unit, and the operation time of the electrochemical advanced oxidation unit, so that each unit could operate within the predicted load range and meet the overall effluent water quality requirements.

[0035] The predictive control strategy adopts a rolling optimization approach, which re-collects the latest influent and operating status data in each control cycle, updates the load forecast, and corrects the effluent flow rate of the regulating tank, the operating rhythm of the high salt tolerance biological treatment unit, and the operating time of the electrochemical advanced oxidation unit for the next control cycle, so as to balance effluent stability and energy economy under fluctuating influent conditions.

[0036] The beneficial effects of this application are:

[0037] This application provides a staged composite treatment method for high-salt oily wastewater. Utilizing a staged combination of highly salt-tolerant biochemical reactions and intelligent electrochemical advanced oxidation, it achieves deep removal and precise staged control of organic pollutants in high-salt oily wastewater, effectively solving the problem of high-salt residual organic matter that is difficult to remove using traditional biochemical processes. By monitoring key parameters such as salinity, oil content, liquid level, conductivity, and organic matter concentration online, and combining dynamic intelligent control of pretreatment dilution and oil removal, highly salt-tolerant SBR aeration and alkali addition, electrochemical current density, and hydraulic retention time, it not only ensures low effluent COD, significantly improved biodegradability, and simultaneous reduction in water toxicity, color, and odor, meeting the dual requirements of wastewater reuse and compliant discharge, but also achieves long-term stable operation and significant energy savings under high-salt and variable organic load conditions. Compared with traditional processes, it effectively reduces the overall energy consumption and operation and maintenance costs of the biochemical and electrochemical units, extends equipment life, reduces maintenance frequency, and the overall process has beneficial effects such as excellent treatment effect, high operational stability, strong environmental friendliness, and good prospects for engineering promotion and application. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the graded and combined treatment method for high-salt and oily wastewater according to this application. Detailed Implementation

[0039] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0040] A graded composite treatment system for high-salt and oily wastewater includes a pretreatment unit, an equalization tank, a high-salt-tolerant biochemical treatment unit, an electrochemical advanced oxidation unit, and a central control device connected in sequence. The units are connected by pipes and valves and are equipped with online detection devices and actuators.

[0041] The pretreatment unit is equipped with an inlet pipeline, a screen, an oil separator, and an online monitoring device for detecting the salinity and oil content of the inlet water. The equalization tank is used for homogenization and flow equalization and is equipped with a level gauge, a conductivity meter, and inlet and outlet control valves. The high-salt-tolerant biological treatment unit is preferably a sequencing batch reactor (SBR) and is equipped with a dissolved oxygen (DO) probe, a pH electrode, an online organic matter concentration monitor, an aeration system, a mixing system, and a sludge return and discharge device. The electrochemical advanced oxidation unit includes an electrolyzer, electrode assembly, a current regulating device, an electrolysis power supply, an online organic matter concentration monitor, and inlet and outlet flow meters and a conductivity meter. The central control unit consists of a PLC controller and a host computer, which are electrically connected to the above-mentioned online monitoring devices and actuators such as valves, pumps, aerators, and electrolysis power supplies to realize the monitoring, control, and optimization calculation of the entire process.

[0042] Based on the above system, such as Figure 1 The method for graded and combined treatment of high-salt and oily wastewater, as shown, includes the following steps:

[0043] S1. Obtain the influent water quality data of the pretreatment unit. When the salinity and / or oil content are higher than the preset threshold, control the addition of recycled water to the equalization tank for dilution, and control the operation of the oil removal device of the pretreatment unit.

[0044] The influent water quality data of the pretreatment unit is collected in real time by online monitoring instruments, including but not limited to online conductivity meters (indirectly characterizing salinity) and online oil content analyzers. The conductivity meter is installed on the inlet pipeline of the pretreatment unit, and the sampling cycle is preferably 10–60 s; the oil content analyzer can use ultraviolet fluorescence or infrared photometry, and the sampling cycle is preferably 1–5 min.

[0045] A preset salinity threshold is set based on the tolerance capacity of the high-salt-tolerance biochemical treatment unit. The upper limit of conductivity corresponding to the salinity threshold is: The oil content threshold is set to The influent water quality is deemed to exceed limits when the monitoring data meets any of the following conditions:

[0046] ;

[0047] in, The real-time conductivity of the water entering the pretreatment unit. This refers to the real-time oil concentration of the influent to the pretreatment unit.

[0048] When any of the above conditions are triggered, the control system automatically calculates the amount of reclaimed water to be added based on the current volume, salinity, and quality of the reclaimed water in the equalization tank, in order to dilute the salinity of the mixed liquor in the equalization tank to the target range. Assuming that the mixture is uniform and the volume change is caused only by the addition of water, the amount of water to be added can be calculated based on material balance.

[0049]

[0050] In the formula, The current liquid volume (m³) in the equalization tank. To adjust the current salinity of the pond (or convert it to equivalent conductivity concentration, in g / L), The salinity of the reclaimed water is typically lower than that of the equalization tank. To achieve the desired target salinity after dilution, This represents the volume (m³) of recycled water that needs to be added.

[0051] Further calculations yielded the required volume of recycled water:

[0052]

[0053] Control system according to The calculation results are used to adjust the opening degree and opening time of the electric valve for recycled water replenishment to achieve automated dilution control. When the liquid level in the equalization tank approaches the upper limit, the system can prevent the equalization tank from overflowing by limiting the volume of water replenished at one time or by adopting a segmented water replenishment strategy.

[0054] Meanwhile, for conditions where oil content exceeds the limit, the pretreatment unit is equipped with an oil removal device, such as a bar screen + oil separator, an air flotation device, or an inclined plate sedimentation + oil skimming system. The control system determines... When the oil content changes, the system automatically sends a start / stop control signal to put the oil removal device into operation. It can also automatically adjust the working frequency of the skimming pump or air flotation aeration according to the changes in oil content, so as to ensure that the oil content of the wastewater entering the equalization tank is reduced to the set range.

[0055] In some embodiments, to avoid frequent start-stop cycles, a dual-threshold control strategy with hysteresis can be adopted for salinity and oil content thresholds, i.e., setting an upper limit threshold. , and lower threshold , The system only activates dilution / de-oiling control when the limit is exceeded, and only stops dilution / de-oiling when the limit is below the lower limit, thereby improving the stability of system operation.

[0056] S2. Obtain the liquid level and conductivity data in the equalization tank. When the liquid level is within the set range and the conductivity is within the target range, control the opening of the inlet valve of the high salt tolerance biological treatment unit so that the wastewater from the equalization tank enters the high salt tolerance biological treatment unit.

[0057] In practical implementation, level gauges (such as ultrasonic level gauges or radar level gauges) and conductivity probes are installed on the sidewalls of the equalization tank. Both the level signal and conductivity signal are connected to a PLC or industrial computer in real time. Level control settings include upper and lower limits: the lower limit is set to... The upper limit of the liquid level is The current liquid level is The target conductivity range is set as follows: .

[0058] The system allows water to be supplied from the equalization tank to the high-salt-tolerance biological treatment unit (such as SBR) and the SBR inlet valve to be opened when the following conditions are met:

[0059]

[0060]

[0061] in, The real-time conductivity of the mixed liquor in the equalization tank.

[0062] When the liquid level in the equalization tank is lower than When the inlet valve is closed, it prevents the biochemical unit from operating without water or from evacuating; when the liquid level is higher than... In case of overflow, the system can activate backup discharge or bypass return measures to avoid overflow risk, and adjust the influent flow rate of the pretreatment unit as needed to alleviate the liquid level pressure in the equalization tank.

[0063] In some embodiments, the effluent from the equalization tank can also be interlocked and controlled according to the current operating stage of the biochemical unit (such as the influent, reaction, sedimentation, and effluent stages of the SBR). For example, the influent valve is only allowed to be opened when the SBR is in the "influent stage" and the liquid level and conductivity of the equalization tank meet the conditions. Automatic linkage between the SBR's periodic operation and the equalization tank effluent can be achieved through time-period control or status signals (such as the "influent allowed" flag).

[0064] In addition, to avoid mechanical failure caused by frequent valve opening and closing, minimum opening time and minimum closing time can be set in practical applications. That is, once the inlet valve is opened, it should be kept open for at least the minimum opening time before it is allowed to be closed again due to signal changes; similarly, after closing, it should wait for at least the minimum closing time before it is allowed to be opened again.

[0065] S3. Control the high salt tolerance biological treatment unit to execute the influent, aeration reaction, sedimentation and drainage steps in a sequential batch manner. During the aeration reaction stage, automatically adjust the aeration rate and alkali dosage according to the changes in dissolved oxygen, pH and effluent organic matter concentration. When the organic matter concentration of the effluent from the high salt tolerance biological treatment unit is detected to be lower than the first target value and the ammonia nitrogen concentration is lower than the second target value, end the current sequential batch cycle and transport the effluent to the electrochemical advanced oxidation unit.

[0066] The high-salt-tolerance biological treatment unit adopts the sequencing batch reactor (SBR) process, and each operating cycle includes an influent stage, an aeration reaction stage, a sedimentation stage, and an effluent stage. The SBR tank is equipped with an online dissolved oxygen (DO) meter, an online pH meter, and an online organic matter monitoring device. In some embodiments, an online ammonia nitrogen analyzer can also be installed at the effluent outlet.

[0067] During the aeration reaction stage, the air supply of the blower or aerator can be controlled by a frequency converter, with a target DO control range of [missing value]. The control system automatically adjusts the fan frequency based on the real-time DO value to achieve closed-loop control. The control quantity can be expressed as:

[0068]

[0069] in, The aeration rate (or frequency) corresponding to the blower at time t. This is the real-time dissolved oxygen concentration. Set a value for the target DO. , , These are the PID parameters. For applications requiring simplified control, only the proportional term can be retained for control.

[0070] Regarding pH adjustment, the online pH signal of the SBR tank is used to control the start / stop or variable frequency flow of the alkali dosing pump. When the pH is below the lower limit... Start the alkali metering pump and add alkali solution (such as NaOH or NaHCO3) into the SBR tank. When the pH is higher than the upper limit... Stop adding the product when necessary to maintain the pH of the reaction system within a suitable range for microbial growth (e.g., 6.5–8.5).

[0071] In some embodiments, the amount of alkali added can also be controlled proportionally based on the pH deviation, for example, by adjusting the alkali flow rate. It can be represented as:

[0072]

[0073] in, For the target pH value, This is the alkali addition ratio coefficient.

[0074] During the reaction process, the system obtains the concentration of organic matter in the effluent through an online organic matter monitoring device. And online ammonia nitrogen analyzer to obtain the ammonia nitrogen concentration in the effluent. The biochemical reaction of the current sequencing batch is considered essentially complete when the following criteria are met:

[0075]

[0076] in, The primary target organic concentration (e.g., 200 mg / L COD or other values ​​set according to emission / subsequent unit requirements). The second target ammonia nitrogen concentration (e.g., 10 mg / L).

[0077] Once the above conditions are simultaneously met, the control system terminates the current aeration reaction phase and sequentially completes the sedimentation and drainage operations. During the sedimentation phase, aeration is stopped and the sludge is allowed to settle for a certain period of time. During the drainage phase, the drain valve is opened to discharge the supernatant to the subsequent electrochemical advanced oxidation unit. To ensure effective sludge-water separation, a maximum drainage height or flow rate can be set, and sludge discharge can be prevented through level control.

[0078] S4. Collect the organic matter concentration, conductivity and flow rate at the inlet of the electrochemical advanced oxidation unit. When the above parameters meet the preset start-up conditions, control the electrolysis power supply to be turned on and carry out electrochemical treatment according to the initial target current density and preset hydraulic residence time.

[0079] An online organic matter concentration analyzer, a conductivity meter, and a flow meter are installed on the inlet water pipeline of the electrochemical advanced oxidation unit to obtain the organic matter concentration of the inlet water. Inlet water conductivity and instantaneous flow The electrochemical reactor contains a cathode and an anode plate, and the effective area of ​​the electrodes is denoted as... Its operating current is controlled by an adjustable power supply.

[0080] To ensure the effective conduction of the electrochemical reaction, the conductivity of the influent must be maintained at or above the minimum conductivity requirement. Otherwise, the conductivity can be increased by adding electrolytes (such as NaCl, Na2SO4, etc.). The preset conditions for starting the electrochemical unit are set as follows:

[0081]

[0082]

[0083]

[0084] in, This is the minimum organic concentration threshold applicable to the electrochemical unit (below this value, it can be considered that further economical removal is difficult). and These represent the minimum and maximum allowed processing traffic, respectively.

[0085] When the above conditions are met simultaneously, the control system starts the electrolysis power supply and operates at the set current density. Running. The relationship between current density and current is:

[0086]

[0087] in, To set the current (A). The target current density.

[0088] The preset hydraulic residence time (HRT) is denoted as Based on the effective volume of the reactor With inflow rate The relationship satisfies:

[0089]

[0090] In intermittent operation mode, the target dwell time can be determined. Control the opening duration of the inlet and outlet valves; in continuous flow mode, this can be achieved by adjusting the inlet pump frequency or setting a timer. Implement the specified HRT.

[0091] In actual operation, the electrochemical unit starts up with a low current density for a slow start-up period, and then gradually increases to the target current density to prevent electrode polarization or instantaneous temperature rise. The current increase process can be controlled in stages.

[0092] S5. During the operation of the electrochemical advanced oxidation unit, collect data on the concentration of organic matter in the influent and effluent and energy consumption. When the concentration of organic matter in the effluent of the electrochemical advanced oxidation unit is detected to be lower than the third target value, control to end the current round of electrochemical treatment and discharge the effluent to the subsequent reuse or compliant discharge unit.

[0093] In practice, online organic matter concentration analyzers are installed at both the inlet and outlet of the electrochemical advanced oxidation unit to obtain the inlet organic matter concentration in real time. and the concentration of organic matter in the effluent At the same time, the power supply system records the voltage. Current And runtime, used to calculate energy consumption metrics.

[0094] During operation, the system can dynamically optimize current density and operating time based on real-time energy consumption and processing results. The energy consumption per unit volume of water is calculated using the following formula:

[0095]

[0096] in, Let P(t) be the actual volume of water processed (m³) within the time interval [0, T], and let P(t) be the instantaneous electrical power (kW), which can be obtained from voltage and current.

[0097]

[0098] In engineering applications that employ approximate discrete records, the above equation can be simplified to:

[0099]

[0100] in , Let be the voltage and current in the k-th time interval, respectively. For the corresponding time length (hours).

[0101] Further calculations of energy consumption per unit of organic matter removal can be performed, for example, using the following formula:

[0102]

[0103] in, This represents the amount of organic matter removed per unit volume of water; the specific unit is calculated based on the monitoring value.

[0104] The target value for the concentration of organic matter in the electrochemical effluent is set as follows: The settings are based on subsequent reuse standards or compliance discharge limits. When the detected organic matter concentration in the effluent meets the following conditions: And remained stable for a period of time. (Used to eliminate instantaneous measurement fluctuations), the control system determines that this round of electrochemical treatment has been completed and automatically performs the following operations:

[0105] 1. Turn off the electrolysis power supply and record the total energy consumption and processing volume for this round of processing;

[0106] 2. Open the valve leading to the subsequent reuse or compliant discharge unit to deliver the compliant effluent to the subsequent unit;

[0107] 3. If necessary, initiate the electrode flushing or polarity reversal program of the electrochemical unit to slow down electrode passivation and scaling.

[0108] In some embodiments, to achieve "economic optimization," the system can also set an energy consumption limit or an operating time limit. When the electrochemical unit has run for longer than the operating time limit or the energy consumption per unit volume exceeds the energy consumption limit and the effluent still fails to reach the third target value, the system can trigger an alarm and stop the current round of electrochemical treatment, returning the effluent to the pre-treatment tank or entering emergency treatment mode to prompt operators to adjust process parameters or maintain electrodes.

[0109] In the above steps, the central control device comprehensively adjusts the effluent flow rate of the equalization tank, the batch operation cycle of the high-salt-tolerant biological treatment unit, and the operating time of the electrochemical advanced oxidation unit based on the water quality and quantity of the influent and effluent of the equalization tank and the energy consumption of each unit, so that the total chemical oxygen demand removal rate of the system meets the following requirements:

[0110] And keep the energy consumption per unit of COD removal within the target range.

[0111] in, The chemical oxygen demand (COD) concentration of the system influent. The chemical oxygen demand (COD) concentration of the overall effluent after treatment by the pretreatment unit, the high salt tolerance biological treatment unit, and the electrochemical advanced oxidation unit. Based on the influent chemical oxygen demand concentration With overall effluent chemical oxygen demand concentration The calculated total chemical oxygen demand removal rate, The target value for total chemical oxygen demand (COD) removal rate;

[0112] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for graded and combined treatment of high-salt, oily wastewater, characterized in that, An applied multi-stage treatment system for high-salt, oily wastewater is provided. The system comprises a pretreatment unit, an equalization tank, a high-salt-tolerant biological treatment unit, an electrochemical advanced oxidation unit, and a central control unit, connected sequentially. The pretreatment unit is equipped with an online monitoring device for detecting influent salinity and oil content. The equalization tank is equipped with level and conductivity monitoring devices. The high-salt-tolerant biological treatment unit is equipped with dissolved oxygen, pH, and organic matter concentration monitoring devices. The electrochemical advanced oxidation unit is equipped with a current regulating device and an organic matter concentration monitoring device. The central control unit is electrically connected to the aforementioned monitoring devices and actuators. The method includes the following steps: The system acquires the influent water quality data of the pretreatment unit. When the salinity and / or oil content are higher than a preset threshold, it controls the addition of recycled water to the equalization tank for dilution and controls the operation of the oil removal device of the pretreatment unit. The liquid level and conductivity data in the equalization tank are obtained. When the liquid level is within a set range and the conductivity is within a target range, the inlet valve of the high salt tolerance biochemical treatment unit is opened to allow wastewater from the equalization tank to enter the high salt tolerance biochemical treatment unit. The high salt tolerance biochemical treatment unit is controlled to sequentially execute the steps of water inlet, aeration reaction, sedimentation and drainage in a batch manner. During the aeration reaction stage, the aeration rate and alkali dosage are automatically adjusted according to the changes in dissolved oxygen, pH and organic matter concentration in the effluent. When the organic matter concentration in the effluent of the high salt tolerance biochemical treatment unit is detected to be lower than the first target value and the ammonia nitrogen concentration is lower than the second target value, the current batch cycle is ended and the effluent is transported to the electrochemical advanced oxidation unit. Organic matter concentration, conductivity and flow rate are collected at the inlet of the electrochemical advanced oxidation unit. When the above parameters meet the preset start-up conditions, the electrolysis power supply is turned on and electrochemical treatment is carried out according to the initial target current density and preset hydraulic residence time. During the operation of the electrochemical advanced oxidation unit, the concentration of organic matter in the influent and effluent and energy consumption data are collected. When the concentration of organic matter in the effluent of the electrochemical advanced oxidation unit is detected to be lower than the third target value, the current round of electrochemical treatment is terminated and the effluent is discharged to the subsequent reuse or compliant discharge unit.

2. The graded and combined treatment method for high-salt and oily wastewater as described in claim 1, characterized in that, In the above steps, the central control device comprehensively adjusts the effluent flow rate of the equalization tank, the sequential batch operation cycle of the high salt tolerance biological treatment unit, and the operating time of the electrochemical advanced oxidation unit based on the water quality and quantity of the influent and effluent of the equalization tank and the energy consumption of each unit, so that the total chemical oxygen demand removal rate of the system meets the following requirements: ； in, The chemical oxygen demand (COD) concentration of the system influent. The chemical oxygen demand (COD) concentration of the overall effluent after treatment by the pretreatment unit, the high salt tolerance biochemical treatment unit, and the electrochemical advanced oxidation unit. Based on the influent chemical oxygen demand concentration With respect to the overall effluent chemical oxygen demand concentration The calculated total chemical oxygen demand removal rate, The target value for the total chemical oxygen demand removal rate; And keep the energy consumption per unit of COD removal within the target range.

3. The graded and combined treatment method for high-salt and oily wastewater as described in claim 1, characterized in that, The central control device, while controlling the operation of the high salt tolerance biochemical treatment unit, is also used to execute an adaptive microbial community reconstruction step based on multi-omics data. The adaptive microbial community reconstruction step includes: Metagenomic or 16S high-throughput sequencing data and metabolic fingerprint data of sludge samples from the high salt tolerance biochemical treatment unit are periodically collected to construct a mapping model between microbial community structure and treatment performance. By correlating the microbial community structure data with the online data of the high salt tolerance biochemical treatment unit, including dissolved oxygen, conductivity, pH, ATP content and chemical oxygen demand removal rate, the influence of the current microbial community composition on the treatment effect of high salt oily wastewater can be obtained. When the mapping model determines that the proportion of core salt-tolerant functional bacteria is lower than the target proportion or the treatment performance of the high salt-tolerant biochemical treatment unit is lower than the preset performance threshold, the high salt-tolerant biochemical treatment unit is controlled to adjust the sludge discharge, return sludge ratio and supplementary bacterial agent dosage so that the relative abundance of the core salt-tolerant functional bacteria is restored to the target range.

4. The graded and composite treatment method for high-salt and oily wastewater as described in claim 3, characterized in that, The adaptive microbial community reconstruction control step also includes a microbial agent dosage adjustment step, including: A target bacterial community composition including multiple types of salt-tolerant degradation bacteria is set, and the actual bacterial community composition of the high salt-tolerant biochemical treatment unit is periodically detected and compared with the target bacterial community composition. When the proportion of one or more target salt-tolerant functional bacteria is detected to be lower than the corresponding preset lower limit, the central control device determines the bacterial agent addition level according to the deviation and controls the bacterial agent addition device to intermittently add the corresponding bacterial agent to the inlet section of the high salt-tolerant biochemical treatment unit. After the microbial agent is added, monitor the changes in the composition of the microbial community and the treatment effect. If the proportion of the target salt-tolerant functional bacteria and the treatment effect reach the preset range, gradually reduce the frequency of microbial agent addition until it is stopped.

5. The graded and combined treatment method for high-salt and oily wastewater as described in claim 1, characterized in that, When the central control device controls the operation of the electrochemical advanced oxidation unit, it performs a back-feedback dynamic optimization control step, including: The operating data of the electrochemical advanced oxidation unit, including the concentration of organic matter in the influent and effluent, voltage, current and energy consumption, are collected. Based on the pre-established process performance evaluation model, the organic matter removal effect and unit energy consumption under the current operating conditions are calculated. In addition, electrode status data including cumulative electrode operating time, cumulative water treatment volume and changes in polarization characteristics are collected, and electrode health indicators are obtained based on the electrode degradation assessment model. A comprehensive evaluation function is constructed with organic matter removal rate, unit energy consumption, and electrode degradation cost as optimization objectives: ； in, The organic matter removal rate of the electrochemical advanced oxidation unit is calculated and determined based on the organic matter concentration in the influent and the organic matter concentration in the effluent of the electrochemical advanced oxidation unit. The specific energy consumption per unit of organic matter removed is calculated based on the electrical energy consumed in the electrochemical advanced oxidation unit to remove a unit mass of organic matter. The equivalent cost index characterizing the degree of electrode degradation under current operating conditions is determined based on the deviation between the electrode health index H and the target health range. , , The weighting coefficients, corresponding to the organic matter removal rate, the specific energy consumption, and the electrode degradation cost, are used to characterize the relative importance of different optimization objectives. By predicting and evaluating different combinations of current density, polarity switching cycle, and hydraulic residence time, the combination that minimizes the comprehensive evaluation function is selected as the target operating condition, and the current density, polarity switching cycle, and operating time of the electrochemical advanced oxidation unit are adjusted accordingly.

6. The graded and combined treatment method for high-salt and oily wastewater as described in claim 5, characterized in that, When the central control device controls the operation of the electrochemical advanced oxidation unit, it performs a reverse feedthrough dynamic optimization control step, including: the electrode degradation cost is determined based on the deviation between the electrode health index and the target health range; when the health is lower than a preset lower limit, the central control device increases the weight of the electrode degradation cost in the comprehensive evaluation function to suppress the selection of high current density and long operating time conditions, thereby extending the electrode service life.

7. The graded and combined treatment method for high-salt and oily wastewater as described in claim 1, characterized in that, When coordinating the control of the regulating tank, the high-salt-tolerant biochemical treatment unit, and the electrochemical advanced oxidation unit, the central control device employs a predictive control strategy for end-to-end collaborative optimization. This predictive control strategy includes: Continuous online monitoring includes key state parameters such as the level of the equalization tank, the concentration of organic matter in the biological effluent, and the concentration of organic matter in the electrochemical effluent. The historical changes and current trends of influent water quality and quantity are used as disturbance inputs to predict the load of each unit in the future period. Based on the prediction results, feedforward adjustments were made to the effluent flow rate of the equalization tank, the batch operation cycle of the high salt tolerance biological treatment unit, and the operation time of the electrochemical advanced oxidation unit, so that each unit could operate within the predicted load range and meet the overall effluent water quality requirements.

8. The graded and composite treatment method for high-salt and oily wastewater as described in claim 7, characterized in that, The predictive control strategy adopts a rolling optimization approach, which re-collects the latest influent and operating status data in each control cycle, updates the load forecast, and corrects the effluent flow rate of the regulating tank, the operating rhythm of the high salt tolerance biological treatment unit, and the operating time of the electrochemical advanced oxidation unit for the next control cycle, so as to balance effluent stability and energy economy under fluctuating influent conditions.

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