A wastewater pretreatment method based on wet oxygen method

Abstract

The application discloses a wastewater pretreatment method based on a wet oxygen method, and particularly relates to the field of wastewater treatment, which comprises sampling and calibrating all wastewater sources, analyzing the content and proportion of organic pollutants, inorganic pollutants and characteristic pollutants in the wastewater, simultaneously determining reference indexes of the wastewater, obtaining analysis results, and classifying the wastewater through the analysis results. Through two-stage operation of the wet oxygen reactor, the scheme realizes ring-opening and chain-breaking reactions of macromolecular organic matter, and further oxidizes and mineralizes small molecules into inorganic products; in the first stage, the generation efficiency of hydroxyl radicals is optimized by using temperature and pressure, and time-sensitive reaction characteristics are decomposed to complex organic matter; in the second stage, the temperature is increased to accelerate the mineralization of small molecules, and the residual organic pollutants are maximally reduced; the problem that the existing wet oxygen method has low treatment efficiency under a single condition is solved, and the removal effect of organic pollutants in the wastewater is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, more particularly, the present application relates to a wastewater pretreatment method based on wet oxygen method. BACKGROUND

[0002] The existing wet oxygen method is mostly used for treating high-concentration organic wastewater, and its advantage lies in that under high-temperature and high-pressure conditions, it can utilize hydroxyl radicals to degrade difficult-to-decompose organic pollutants. However, the traditional wet oxygen method is usually operated under a single reaction condition, and does not perform segmented treatment according to the characteristics of different pollutants, resulting in insufficient degradation of some macromolecular organic matter and difficulty in complete mineralization of small-molecule organic matter. In addition, volatile organic matter may cause explosion or corrosion of equipment under high-temperature and high-pressure conditions, and the treatment of tail gas and the utilization of waste heat are not fully optimized. These problems limit the wide application of the wet oxygen method in the treatment of complex wastewater.

[0003] The single reaction condition of the traditional wet oxygen method is difficult to adapt to the degradation needs of various organic matters in wastewater, especially when treating complex wastewater, the reaction condition cannot be adjusted according to the time and temperature sensitivity, resulting in low degradation efficiency and insufficient mineralization. For example, in actual operation, high-concentration macromolecular pollutants need a longer time for decomposition, and small-molecule pollutants need a higher temperature to achieve complete oxidation. Therefore, the traditional process has efficiency bottlenecks when treating different pollutants, and cannot effectively control the biodegradability of the subsequent oxidation liquid, which brings challenges to the subsequent biochemical treatment. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide a wastewater pretreatment method based on wet oxygen method, which realizes the ring-opening and chain-breaking reaction of macromolecular organic matter through two-stage operation of the wet oxygen reactor, and further oxidizes and mineralizes small molecules into inorganic products. In the first stage, the generation efficiency of hydroxyl radicals is optimized by temperature and pressure, and complex organic matter is decomposed according to the time-sensitive reaction characteristics. In the second stage, the temperature is increased to accelerate the mineralization of small molecules, and the residual organic pollutants are minimized to solve the problems raised in the above background.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a wastewater pretreatment method based on wet oxygen method, comprising:

[0006] First, sample and calibrate all wastewater sources, analyze the content and proportion of organic pollutants, inorganic pollutants and characteristic pollutants in the wastewater, and determine the reference index of the wastewater, obtain the analysis results, and classify the wastewater through the analysis results;

[0007] Then, for the volatile organic matter existing in the wastewater, light removal pretreatment is carried out by heating or flash evaporation;

[0008] The suspended particulate pollutants in the wastewater are removed by a filter before the wastewater enters the wet oxygen reactor;

[0009] The removal effect of the organic pollutants in the wastewater and the feasibility of subsequent treatment are determined based on the wet oxygen reactor through two-stage operation; the first-stage operation includes controlling the temperature at 150-200°C and maintaining the pressure at 5-7 MPa, so that the macromolecular organic matter is subjected to ring-opening and chain-breaking reactions by hydroxyl radicals to generate intermediate products with good biodegradability; the second-stage operation increases the temperature to 250-300°C and maintains the pressure at 7-8 MPa;

[0010] When the pH value of the oxidation liquid generated after the wet oxygen treatment is lower than a preset pH threshold value, an alkaline neutralizing agent is added until the pH value is adjusted to be within the preset pH threshold range; when the biodegradability of the oxidation liquid is higher than a preset biodegradability threshold value through B / C ratio testing, the oxidation liquid is directly subjected to biochemical treatment; when the B / C ratio is lower than a preset B / C ratio threshold value, a biological activity agent is added or secondary oxidation treatment is implemented;

[0011] The water vapor in the tail gas is condensed and separated by flashing, and volatile organic compounds are captured, followed by removal of residual harmful gases in the tail gas by activated carbon adsorption; the tail gas waste heat is recovered by a heat exchanger and used for preheating the wastewater or providing low-pressure steam;

[0012] In the trial operation stage, an online monitoring model is established based on the evaluation of the engineering risks of the wet oxygen method, and the online monitoring model includes equipment operation state monitoring, corrosion condition evaluation, and operation parameter optimization.

[0013] In a preferred embodiment, the reference indexes include chemical oxygen demand, biochemical oxygen demand, B / C ratio, pH value, and total dissolved solids; and the characteristic pollutants include acetone, dichloromethane, ammonia nitrogen at a preset concentration, and macromolecular organic matter with sugar-like properties.

[0014] In a preferred embodiment, the wastewater is classified based on a multi-index comprehensive decision model and the reference indexes are calculated.

[0015]

[0016] wherein Z is a comprehensive pollution index; w i is a dynamic weight of the ith index; λ i is an influence coefficient of the ith index on the system; M i is an actual value of the ith index; M i,min , M i,max respectively represent a lower limit value and an upper limit value of the ith index; γ i is a nonlinear adjustment index of the ith index;

[0017] The separation efficiency of volatile organic compounds is calculated by a mass transfer model by comprehensively considering gas-liquid equilibrium and mass transfer resistance;

[0018]

[0019] wherein E VOC is the separation efficiency of volatile organic compounds; k L is the liquid phase mass transfer coefficient; a is the ratio of gas-liquid contact area; H is the Henry coefficient; C L is the actual concentration of volatile organic compounds in the liquid phase; C L,eq is the equilibrium concentration of volatile organic compounds in the liquid phase.

[0020] In a preferred embodiment, in the filtration removal of suspended particles, the step-by-step interception of suspended particles by each layer of filter screen is described based on the superposition effect of pressure drop; a cumulative resistance model is established, and the filtration efficiency is analyzed by the cumulative resistance model to consider the comprehensive effect of multiple layers of filter screens;

[0021]

[0022] wherein η filter is the multi-layer filtration efficiency; ΔP i is the pressure drop of the i-th layer of filter screen; P in is the inlet pressure; and m is the number of filter screen layers.

[0023] In a preferred embodiment, the dual effects of time and temperature are coupled, and the reaction order is introduced to describe the degradation characteristics of different stages; the degradation characteristics include that the first stage is sensitive to time and the second stage is sensitive to temperature; a two-parameter kinetic model of the wet oxygen reaction degradation process is established based on the two-stage operation of the wet oxygen reactor;

[0024]

[0025] wherein C t and C0 are the pollutant concentrations at time t and initial time, respectively; k1 and k2 are the influence coefficients of time and temperature on the reaction rate, respectively; β1 and β2 are the reaction orders of time and temperature, respectively; t is the reaction time; and T is the reaction temperature.

[0026] In a preferred embodiment, in the post-treatment and regulation of the oxidation liquid, the comprehensive effect of chemical regulation and biological enhancement is embodied by coupling the synergistic effect of active agent dosage and pH, and a B / C ratio regulation model of the oxidation liquid is established by combining active agent dosage and oxidation enhancement:

[0027] B / C new = (B / C orig + κC bio ) · (1 + θe -pH )

[0028] wherein B / C new is the regulated B / C ratio; B / C orig is the original B / C ratio; K is the active agent intensification coefficient; C bio is the active agent dosage; Q is the influence weight of pH on the regulated B / C ratio; -pH is the exponential decay factor of pH value on the regulation effect.

[0029] Technical effects and advantages of the present application:

[0030] 1. The two-stage operation of the wet oxygen reactor is used to realize the ring-opening and chain-breaking reactions of macromolecular organic matter, and further oxidize small molecules into inorganic products; the first stage optimizes the generation efficiency of hydroxyl radicals by using temperature and pressure, and decomposes complex organic matter according to the time-sensitive reaction characteristics; the second stage accelerates the mineralization of small molecules by increasing the temperature, and maximizes the reduction of residual organic pollutants; the problem of low treatment efficiency of the existing wet oxygen method under a single condition is solved, and the removal effect of organic pollutants in wastewater is improved;

[0031] 2. The heating or flash evaporation technology is used to treat volatile organic matter in wastewater, prevent safety hazards under high temperature and high pressure conditions, and reduce the burden of volatile components on the wet oxygen reactor;

[0032] 3. The B / C ratio regulation model of the oxidation liquid is constructed, the synergistic effect of active agent dosage and pH regulation is combined, and the biodegradability of the oxidation liquid is dynamically optimized; through the adjustment of the active agent intensification coefficient and the pH exponential decay factor, the regulation of the composition of the oxidation liquid is realized, so as to ensure the applicability of subsequent biochemical treatment;

[0033] 4. The combination technology of flash evaporation and activated carbon adsorption is used to remove volatile organic matter and residual harmful gases in tail gas, and the waste heat of tail gas is recovered through a heat exchanger for wastewater preheating or low-pressure steam supply, which optimizes the energy efficiency of the system and reduces the operation cost. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is the flowchart of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] Referring to the drawings in the description Figure 1An embodiment of the present application is a wastewater pretreatment method based on the wet oxidation method, comprising:

[0037] Step 1: wastewater source and composition analysis

[0038] First, all wastewater sources are sampled and calibrated, and the content and proportion of organic pollutants, inorganic pollutants, and characteristic pollutants in the wastewater are analyzed. At the same time, the reference index of the wastewater is determined, the analysis results are obtained, and the wastewater is classified through the analysis results;

[0039] Step 2: light removal pretreatment

[0040] Next, the volatile organic compounds in the wastewater are pretreated by heating or flashing to reduce the burden on the wet oxygen device. The light removal tower is the core equipment, which preheats the wastewater to 60–70℃, separates the light components from the water by using the low boiling point characteristics of the light components, and maintains the pressure at normal pressure to 1.2 MPa by using steam direct heating to ensure that the light components are fully volatilized. At the same time, the volatile matter is captured and recovered by the tail gas condensing device, and the recovered light components are further treated or safely disposed according to their properties to prevent secondary pollution. After light removal, the concentration of volatile organic compounds (such as VOC) in the wastewater needs to be reduced to less than 50 mg / L to meet the safety operation requirements of the subsequent wet oxygen reactor;

[0041] Step 3: removal of suspended solids

[0042] Before the wastewater enters the wet oxygen reactor, the suspended particulate pollutants in the wastewater are removed by a filter to avoid plugging and coking in a high-temperature and high-pressure environment. This step sets up a duplex precision filter with one in use and one in standby, with a filtration accuracy of 0.1–0.5 mm. The filter screen material is recommended to be a strong corrosion-resistant alloy material. After filtration, the particulate removal rate needs to be evaluated by online monitoring to ensure that the concentration of suspended particulate matter is less than 50 ppm. At the same time, the filter can be equipped with an online backwashing function to clean it once every 8–12 hours to maintain efficient operation;

[0043] Step 4: wet oxygen reaction process optimization

[0044] The removal effect of organic pollutants in wastewater and the feasibility of subsequent treatment are determined by two-stage operation based on a wet oxygen reactor. The first stage operation includes controlling the temperature at 150-200°C and maintaining the pressure at 5-7 MPa, so that the hydroxyl radicals can perform ring-opening and chain-breaking reactions on macromolecular organic matter to generate intermediate products with good biodegradability, including small-molecule organic acids. In the second stage, the temperature is increased to 250-300°C and the pressure is maintained at 7-8 MPa to oxidize small-molecule organic matter and mineralize it into inorganic products such as CO2, H2O, and NH3 as much as possible. Compressed air is used to supply oxygen, and the excess oxygen ratio is maintained at 2.0-2.5 by a flow control valve to ensure efficient generation of hydroxyl radicals in the reaction system. The COD removal rate of the reaction effluent is monitored in real time online, and the target is to achieve a single-pass removal rate of ≥70%.

[0045] Step 5: Post-treatment and regulation of oxidation liquid

[0046] When the pH value of the oxidation liquid produced after wet oxygen treatment is lower than the preset pH threshold, an alkaline neutralizing agent including NaOH or Ca(OH)2 is added until the pH value is adjusted to within the preset pH threshold range to prevent corrosion of the oxidation liquid on subsequent pipelines and equipment. When the biodegradability of the oxidation liquid is higher than the preset biodegradability threshold through B / C ratio testing, biochemical treatment is directly performed. When the B / C ratio is lower than the preset B / C ratio threshold, a biological activator is added or secondary oxidation treatment is implemented to improve the biodegradability. In addition, when high-salt components are detected in the oxidation liquid, low-temperature evaporation concentration process is used to separate inorganic salts before biochemical treatment to ensure that the oxidation liquid meets the discharge standard requirements.

[0047] Step 6: Tail gas purification and waste heat recovery

[0048] Water vapor in the tail gas is condensed and separated by flashing and trace volatile organic compounds are captured. Then, activated carbon adsorption is used to remove harmful gases remaining in the tail gas. Tail gas waste heat is recovered by a heat exchanger for preheating wastewater or providing low-pressure steam.

[0049] Step 7: Engineering risk assessment and optimization improvement

[0050] During the trial operation stage, based on the engineering risk assessment of the wet oxygen method, an online monitoring model is established, including equipment operation state monitoring, corrosion condition evaluation, and operation parameter optimization.

[0051] It should be noted that: the above scheme is based on the characteristics of wet oxygen method, combined with the actual treatment needs of wastewater composition, through step-by-step optimization of the treatment process, to achieve efficient pollutant removal and equipment running stability; first, for the diversified organic pollutants, inorganic pollutants and characteristic pollutants in wastewater, through sampling calibration and analysis classification, accurate basis is provided for phased treatment, in order to avoid the waste of resources and low processing efficiency caused by one-size-fits-all;

[0052] For the removal of volatile organic compounds, heating or flash evaporation technology is used, which is based on the physical properties of volatile components, such as low boiling point and high volatility, and the potential safety hazards caused by them in high temperature and high pressure environment, therefore, the temperature range of 60℃-70℃ and the pressure range of normal pressure to 1.2MPa are set, which are derived from the gas-liquid equilibrium conditions verified by experiments, to ensure the sufficient removal of volatile organic compounds; in the wet oxygen reaction, the step-by-step degradation of pollutants is realized through staged operation (first stage 150℃-200℃, 5MPa-7MPa; second stage 250℃-300℃, 7MPa-8MPa), the first stage conditions are suitable for ring-opening and chain-breaking reactions of macromolecular organic matter, and the degradation efficiency is improved by hydroxyl radicals, and the second stage accelerates the mineralization of small molecules into inorganic matter by higher temperature and pressure; when the pH of the treated oxidation liquid is lower than the preset range, it is adjusted to neutral by adding alkali neutralizing agent, because the neutral environment can effectively prevent pipeline and equipment corrosion; at the same time, whether the oxidation liquid is suitable for direct biochemical treatment or needs further intensified treatment is judged by B / C ratio test, based on which, the economic efficiency and treatment effect of the system are ensured; tail gas treatment adopts flash evaporation and activated carbon adsorption design, which is based on the fact that volatile organic compounds and harmful gases in tail gas need to be separated by physical separation and chemically adsorbed to ensure standard emission, at the same time, the tail gas waste heat is recycled through heat exchanger for wastewater preheating or steam supply, which not only improves energy efficiency, but also reduces operating cost;

[0053] The reference indexes include chemical oxygen demand, biochemical oxygen demand, B / C ratio, pH value and total dissolved solids; the characteristic pollutants include acetone, dichloromethane, ammonia nitrogen of preset concentration, and macromolecular organic matter of sugar-like nature.

[0054] Based on the multi-index comprehensive decision model, wastewater classification and reference index calculation are carried out.

[0055]

[0056] Wherein Z is the comprehensive pollution index, which is used to reflect the overall pollution severity of wastewater; w i is the dynamic weight of the ith index; λ i is the influence coefficient of the ith index on the system; M i is the actual value of the ith index; M i,min , M i,maxrespectively represent the lower limit value and the upper limit value of the i-th index; γ i is the nonlinear adjustment index of the i-th index, which is used to amplify or weaken the influence of a certain index;

[0057] By comprehensively considering the gas-liquid equilibrium and mass transfer resistance, the separation efficiency of volatile organic compounds is calculated by a mass transfer model;

[0058]

[0059] where E VOC is the separation efficiency of volatile organic compounds; k L is the liquid phase mass transfer coefficient, which is used to reflect the transfer rate of solute in the liquid phase; a is the ratio of gas-liquid contact area; H is the Henry coefficient, which is used to represent the gas-liquid equilibrium characteristics of the solute; C L is the actual concentration of volatile organic compounds in the liquid phase; C L,eq is the equilibrium concentration of volatile organic compounds in the liquid phase;

[0060] By combining the Henry's law with the mass transfer rate model, the efficiency of volatile organic compounds transferring from the liquid phase to the gas phase is reflected, and the mass transfer coefficient k L and the contact area a are improved by equipment optimization, while the Henry coefficient is related to the physical parameters of volatile organic compounds;

[0061] In addition, the above scheme adopts a multi-index comprehensive decision model for wastewater classification and reference index calculation. The core of this step is to reflect the overall pollution degree of wastewater by building a comprehensive pollution index, in which dynamic weights and nonlinear adjustment indexes are introduced to flexibly adjust the importance and influence range of each index. The necessity of this design lies in the complexity of wastewater composition. For example, chemical oxygen demand may have a larger weight in some wastewater treatment, while total dissolved solids may be more critical in other cases. Therefore, dynamic weight allocation and amplification or weakening of specific indexes are needed to ensure that the model is adaptable and the classification is reasonable. Secondly, the separation of volatile organic compounds uses a mass transfer model to describe the process of volatile organic compounds transferring from the liquid phase to the gas phase by combining gas-liquid equilibrium and mass transfer resistance. The mass transfer coefficient and the contact area are determined by equipment optimization, while the Henry coefficient is related to the physical parameters of volatile organic compounds. The principle of the design is to improve the gas-liquid contact efficiency and optimize the equipment structure to maximize the separation effect.

[0062] In the filtration removal of suspended particles, the superposition effect of pressure drop is used to describe the step-by-step interception of each layer of filter screen to suspended particles. A cumulative resistance model is established, and the cumulative resistance model is used to analyze the filtration efficiency considering the comprehensive action of multiple layers of filter screen.

[0063]

[0064] where ηfilter is the filtration efficiency of the multi-layer filter; ΔP is the pressure drop of the multi-layer filter; i is the layer number of the filter; P is the pressure drop of the i th layer of the filter; m is the number of layers of the filter; P in is the inlet pressure; and P out is the outlet pressure. i is the filtration efficiency of the multi-layer filter; ΔP is the pressure drop of the multi-layer filter; i is the layer number of the filter; P is the pressure drop of the i th layer of the filter; m is the number of layers of the filter; P in is the inlet pressure; and P out is the outlet pressure. in is the filtration efficiency of the multi-layer filter; ΔP is the pressure drop of the multi-layer filter; i is the layer number of the filter; P is the pressure drop of the i th layer of the filter; m is the number of layers of the filter; P in is the inlet pressure; and P out is the outlet pressure.

[0065] The filtration efficiency model of the multi-layer filter based on the pressure drop superposition effect is used to describe the gradual interception of particles when wastewater passes through the multi-layer filter. By regarding the interception effect of each layer of the filter as an independent pressure drop contribution, the overall filtration efficiency of the multi-layer filter is comprehensively analyzed by the cumulative resistance model. Specifically, the filtration efficiency is related to the ratio of the pressure drop of each layer of the filter to the inlet pressure. The greater the pressure drop, the higher the proportion of particles intercepted. The multi-layer filter gradually improves the overall filtration efficiency through the superposition effect of the pressure drop, thereby achieving efficient removal of suspended particles. The pressure drop ratio of each layer of the filter in the above formula reflects the reduction of the particle penetration probability, and the unified standardized treatment of the inlet pressure makes the model adaptable to different operating conditions. Based on the complexity in actual wastewater treatment, the suspended particles may have diversified particle size and distribution characteristics, and a single layer of the filter often cannot fully meet the demand for efficient removal. Therefore, a multi-layer filter design is adopted to enhance the filtration capacity, and the cumulative resistance model is used to avoid redundant design caused by the increase in the number of layers of the filter.

[0066] The dual influence of time and temperature is coupled, and the reaction order is introduced to describe the degradation characteristics in different stages. The degradation characteristics include that the first stage is sensitive to time and the second stage is sensitive to temperature. A two-parameter kinetic model of the wet oxygen reaction degradation process is established based on the two-stage operation of the wet oxygen reactor.

[0067]

[0068] wherein C t and C 0 are the pollutant concentrations at time t and the initial time, respectively; k 1 and k 2 are the influence coefficients of time and temperature on the reaction rate, respectively; β 1 and β 2 are the reaction orders of time and temperature, respectively; t is the reaction time; and T is the reaction temperature. t , C 0 are the pollutant concentrations at time t and the initial time, respectively; k 1 and k 2 are the influence coefficients of time and temperature on the reaction rate, respectively; β 1 and β 2 are the reaction orders of time and temperature, respectively; t is the reaction time; and T is the reaction temperature.

[0069] A two-parameter kinetic model of the wet oxygen reaction degradation is constructed to couple the dual influence of time and temperature, which is used to describe the degradation characteristics of pollutants in different stages. The first stage relies on time to break the chain and open the ring of macromolecular organic matter, and the second stage accelerates the mineralization of small molecules into inorganic matter through higher temperature. The time and temperature sensitivity parameters and the response order introduced in the formula accurately depict the contribution of the two to the degradation rate. The above formula is based on the wet oxygen reaction mechanism and combines dynamic adjustment of the reaction conditions to realize accurate control of the pollutant removal effect.

[0070] In the post-treatment and regulation of the oxidation liquid, the synergistic effect of the coupling of the active agent dosage and pH is used to reflect the comprehensive effect of chemical regulation and biological enhancement, and the B / C ratio regulation model of the oxidation liquid is established by combining the active agent dosage and oxidation enhancement:

[0071] B / C new = (B / C orig + κC bio ) · (1 + θe -pH )

[0072] Wherein B / C new is the regulated B / C ratio; B / C orig is the original B / C ratio; κ is the active agent enhancement coefficient; C bio is the active agent dosage; θ is the influence weight of pH on the regulated B / C ratio; -pH is the exponential attenuation factor of pH value on the regulation effect, - is the attenuation rate coefficient, and pH is the acid-base value of the solution.

[0073] By constructing the B / C ratio regulation model of the oxidation liquid, the synergistic effect of the active agent dosage and pH value is used to realize the comprehensive effect of chemical regulation and biological enhancement; in the formula, the dosage of the active agent affects the biodegradability improvement range, the pH value adjusts the regulation efficiency through the exponential term, and the dynamic influence of the acid-base condition on the biochemical effect is embodied; the regulated B / C ratio is determined by the original B / C ratio, the active agent enhancement coefficient and the pH value attenuation factor; this model is designed because the biodegradability in the oxidation liquid needs to be optimized under the conditions of chemistry and biology, and the coupling of the active agent and pH value can significantly enhance the degradation effect; in practical application, the model provides a scientific basis for the active agent dosage optimization and the oxidation liquid regulation, simultaneously dynamically adapts to different wastewater characteristics, and ensures the economy and effectiveness of the subsequent treatment.

[0074] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A wastewater pretreatment method based on wet oxygenation, characterized in that, include: First, all wastewater sources were sampled and calibrated. The content and proportion of organic pollutants, inorganic pollutants, and characteristic pollutants in the wastewater were analyzed. At the same time, reference indicators of the wastewater were measured to obtain the analysis results. The wastewater was then classified based on the analysis results. Next, for the volatile organic compounds present in the wastewater, light organic matter removal pretreatment is carried out by heating or flash evaporation; Before the wastewater enters the wet oxygen reactor, suspended particulate pollutants in the wastewater are removed by a filter; The wet oxygen reactor is used to determine the removal efficiency of organic pollutants in wastewater and the feasibility of subsequent treatment through two-stage operation. The first stage operation includes temperature control at 150℃–200℃ and pressure maintenance at 5MPa–7MPa. The hydroxyl radicals are used to carry out ring-opening and chain-breaking reactions on macromolecular organics to generate intermediate products with good biodegradability. The second stage involves raising the temperature to 250℃–300℃ while maintaining the pressure at 7MPa–8MPa. If the pH value of the oxidizing solution produced after wet oxygen treatment is lower than the preset pH threshold, an alkaline neutralizing agent is added until the pH value is adjusted to the preset pH threshold range; if the biodegradability of the oxidizing solution is higher than the preset biodegradability threshold as determined by the B / C ratio test, biochemical treatment is carried out directly; if the B / C ratio is lower than the preset B / C ratio threshold, a bioactive agent is added or a secondary oxidation treatment is implemented. The water vapor in the exhaust gas is condensed and separated by flash evaporation, and volatile organic compounds are captured. Then, the residual harmful gases in the exhaust gas are removed by activated carbon adsorption. Waste heat from exhaust gas is recovered via a heat exchanger and used to preheat wastewater or provide low-pressure steam. During the trial operation phase, based on the assessment of the engineering risks of the wet oxygen method, an online monitoring model was established. The online monitoring model includes equipment operating status monitoring, corrosion status assessment, and operating parameter optimization. In the post-treatment and regulation of the oxidation solution, the synergistic effect of coupled surfactant dosage and pH is used to reflect the comprehensive role of chemical regulation and biofortification. A B / C ratio regulation model for the oxidation solution is established by combining surfactant dosage and oxidation enhancement. in The adjusted B / C ratio; This is the original B / C ratio; The surfactant enhancement coefficient; This refers to the amount of surfactant added. The weighting of the effect of pH on the adjusted B / C ratio; This is the exponential decay factor for the effect of pH on regulation.

2. The wastewater pretreatment method based on wet oxygenation according to claim 1, characterized in that: The reference indicators include chemical oxygen demand (COD), biochemical oxygen demand (BOD), B / C ratio, pH value, and total dissolved solids; characteristic pollutants include acetone, dichloromethane, ammonia nitrogen at a preset concentration, and large organic molecules with sugar-like properties.

3. The wastewater pretreatment method based on wet oxygenation according to claim 2, characterized in that: Based on a multi-index comprehensive decision-making model, wastewater classification and reference index calculation are performed. in The comprehensive pollution index; For the first Dynamic weights of each indicator; It is the first The influence coefficient of each indicator on the system; For the first The actual value of each indicator; , They represent the first The lower and upper limits of each indicator; For the first The nonlinear adjustment index of each indicator.

4. The wastewater pretreatment method based on wet oxygenation according to claim 1, characterized in that: The degradation characteristics at different stages are described by coupling the dual effects of time and temperature and introducing reaction order; the degradation characteristics include the first stage being time-sensitive and the second stage being temperature-sensitive. A two-parameter kinetic model of the wet oxygen reaction degradation process was established based on the two-stage operation of the wet oxygen reactor. in , They are respectively Pollutant concentrations at time 1 and the initial time; , These are the coefficients representing the effects of time and temperature on the reaction rate; , These represent the reaction order based on time and temperature, respectively. Reaction time; The reaction temperature is denoted as .

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