A wastewater treatment method based on a modified wet oxidation reaction

Abstract

The application discloses a wastewater treatment method based on a modified wet oxidation reaction, which comprises the following steps: step 1, after wastewater is treated by modification, the wastewater is preheated by a multi-stage heat exchanger; step 2, the preheated wastewater and an oxidant are jointly introduced into a wet oxidation tower provided with a solid catalyst, and the wet oxidation tower is gradually heated to a required reaction temperature to perform a wet oxidation reaction; step 3, a gas-liquid mixture flowing out of the wet oxidation tower is subjected to gas-liquid separation, and both the separated gas phase and the liquid phase are introduced into the multi-stage heat exchanger in step 1 to perform heat exchange with the wastewater in step 1, so that the wastewater is preheated; and step 4, the cooled gas phase and the liquid phase are separated again, the separated gas phase is introduced into the wastewater in step 1 to modify the wastewater, and the separated liquid phase is further treated or discharged. The method can effectively degrade organic pollutants in the wastewater, has low energy consumption and operation cost, and is stable in process operation.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a wastewater treatment method based on a modified wet oxidation reaction. Background Technology

[0002] High-concentration organic wastewater mainly comes from industries such as pesticides, pharmaceuticals, coking, dyes, printing and dyeing, petrochemicals, and leather. It usually contains substances such as hydrocarbons, oils, organic sulfur, and inorganic sulfur. This type of wastewater is characterized by complex composition, stable structure, and difficulty in degradation by biochemical or physicochemical methods.

[0003] Currently, wet oxidation technology is widely recognized as an effective technology for treating high-concentration organic wastewater. This technology uses air, ozone, pure oxygen, or hydrogen peroxide as oxidants under high temperature and high pressure conditions to oxidize dissolved or suspended organic matter or reduced inorganic matter in the water, generating CO2 and small molecules, thus purifying the wastewater. Compared with other traditional treatment methods, wet oxidation technology has the advantages of wide applicability, high treatment efficiency, fast oxidation rate, energy and useful material recovery, and less secondary pollution. Therefore, it has received widespread attention from researchers worldwide and is a promising water treatment method.

[0004] While wet oxidation technology is relatively mature, it still has some drawbacks:

[0005] 1. When wet oxidation treats high-concentration, recalcitrant organic wastewater, the reaction temperature is usually 200℃ and the pressure is 5-6MPa, and the range of wastewater that can be treated is narrow.

[0006] 2. The concentration range of organic matter in the influent is limited, and the COD of the influent is generally controlled within 60,000 mg / L, limiting the types of wastewater that can be treated.

[0007] 3. When treating organic wastewater, the COD degradation rate is low, and the conversion rate of difficult-to-biodegrade macromolecules into easily biodegradable small molecules is low.

[0008] 4. Wet oxidation reactions require high temperature and pressure conditions, resulting in high energy consumption and operating costs;

[0009] 5. During the wastewater treatment process, organic matter in the wastewater is very likely to scale and clog the heat exchangers and heaters, resulting in low heat exchange and heating efficiency and the inability to operate the process continuously and stably.

[0010] Therefore, the application of wet oxidation technology in the treatment of high-concentration organic wastewater is limited. In order to overcome the problems of the existing technology, there is a need for a high-salt, high-organic-content, and high-toxicity wastewater treatment technology that has a wide range of applications, high COD removal rate, low energy consumption and operating cost, and stable process operation. Summary of the Invention

[0011] Objective of the Invention: To address the problems existing in the prior art, this invention provides a wastewater treatment method based on a modified wet oxidation reaction. For high-concentration, recalcitrant wastewater, the modified wet oxidation reaction technology of this invention has a wide range of applications, high COD removal rate, low energy consumption and operating costs, and stable process operation. It can effectively degrade organic pollutants in wastewater, improve the biodegradability of wastewater, and ultimately achieve the goal of wastewater meeting discharge standards.

[0012] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A wastewater treatment method based on a modified wet oxidation reaction includes the following steps:

[0014] Step 1: After the wastewater has been treated with conditioning and modification, it is preheated and heated using a multi-stage heat exchanger.

[0015] Step 2: The preheated wastewater and oxidant are fed together into a wet oxidation tower containing a solid catalyst, and the temperature is gradually increased to the required reaction temperature to carry out the wet oxidation reaction.

[0016] Step 3: Separate the gas-liquid mixture flowing out of the wet oxidation tower. The separated gas and liquid phases enter the multi-stage heat exchanger described in Step 1. After exchanging heat with the wastewater in Step 1, the wastewater is preheated and the gas and liquid phases form a gas-liquid mixture again.

[0017] Step 4: The gas-liquid mixture after heat exchange is separated again. The separated gas phase enters the wastewater from Step 1 to condition and modify the wastewater, while the separated liquid phase is further treated or discharged.

[0018] As a specific implementation plan, in step 1, the wastewater is wastewater from multiple fields such as pesticides, pharmaceuticals, coking, dyes, printing and dyeing, petrochemicals, or leather with an influent COD concentration of less than 100,000 mg / L.

[0019] As a specific implementation plan, in step 1, the multi-stage heat exchanger consists of several heat exchangers connected in series; after the preheating and heating, the wastewater temperature reaches 180-200℃, which reduces the temperature rise during final heating and reduces operating energy consumption.

[0020] As a specific implementation plan, in step 2, the oxidant is selected from air; the temperature of the wet oxidation reaction is 200-260℃, the reaction pressure is 2-8MPa, the reaction temperature and pressure can be adjusted in real time according to the raw water concentration and the reaction process, and the reaction residence time is 40-60min.

[0021] As a specific implementation scheme, in step 2, the solid catalyst is a metal oxide supported catalyst, in which the metal oxide is coated with a support, which can screen for various organic substances with different structures in the wastewater; preferably, the metal combination supported on the support includes CuO-MnO-CeO, FeO-CuO-MnO or CuO-ZnO-CeO, and the support is TiO2 support. This solid catalyst has good anti-leakage performance, short reaction residence time, and a wastewater COD removal rate of over 90%, and the biodegradability (B / C) of the oxidized wastewater is increased to over 0.4.

[0022] As a specific implementation plan, in step 2, the gradual heating involves dividing the wet oxidation tower into a low-temperature reaction zone and a high-temperature reaction zone. The temperature in the low-temperature reaction zone is 200-240℃, and the temperature in the high-temperature zone is 220-260℃. Wastewater enters the wet oxidation reaction tower and passes through the low-temperature zone and the high-temperature zone in sequence, gradually heating up to the final reaction temperature. The temperature rise is reduced, ensuring system safety.

[0023] As a specific implementation plan, in step 3, the gas-liquid separation adopts a high-pressure gas-liquid separator.

[0024] As a specific implementation plan, in step 4, the gas-liquid separation adopts a low-pressure gas-liquid separator.

[0025] As a specific implementation plan, in step 4, the main components of the wastewater after wet oxidation are small molecule acids, which are easy to treat biochemically; the advanced treatment includes using A / O, SBR or MBR biochemical treatment technologies to further remove organic pollutants from the wastewater.

[0026] In this invention, during the wet oxidation reaction, organic matter in the wastewater is oxidized, releasing a large amount of heat to maintain a constant temperature in the mixed liquid. A multi-stage heat exchanger is used to recover this heat. The high-temperature material discharged from the wet oxidation tower is separated, with both the gas and liquid phases flowing sequentially through the multi-stage heat exchanger to preheat the influent, forming a reaction cycle. This multi-stage preheating reduces the temperature rise during final heating, lowering energy consumption and cost. The gas and liquid phases entering the multi-stage heat exchanger then form a gas-liquid mixture again. Finally, the gas phase separated again by a low-pressure gas-liquid separator is fed into the original wastewater storage tank, enabling the recovery and utilization of pressure and residual oxygen in the post-reaction gas, further reducing energy consumption and cost. Simultaneously, the gas phase generated is rich in CO2 (approximately 20%-80% by volume), which can chemically react with salts in the original wastewater to generate bicarbonate, reducing system scaling and achieving conditioning and modification of the original wastewater, ensuring stable process operation.

[0027] Beneficial Effects: Compared with existing technologies, the method of this invention is applicable to wastewater from multiple fields and has a wide range of applications. The use of a multi-metal oxide supported catalyst enables the effective degradation of organic pollutants in wastewater, resulting in high biodegradability and treatment efficiency. Furthermore, by performing multi-stage preheating and gradual temperature increase on the wet oxidation tower feed liquid, and by recovering and utilizing the large amount of heat released from the oxidation reaction, as well as the pressure and residual oxygen in the post-reaction gas, energy consumption and operating costs are reduced, ensuring safe system operation. Simultaneously, the CO2-rich gas phase generated by the reaction chemically reacts with salts in the original wastewater to produce bicarbonate, which reduces scaling in the system, achieving conditioning and modification of the original wastewater, and ensuring stable process operation. Attached Figure Description

[0028] Figure 1 This is a flow chart of the wet oxidation process for treating high-salt, high-organic, and high-toxicity wastewater provided by the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0030] An improved wet oxidation reaction technology specifically includes the following steps:

[0031] Step 1: After conditioning and modification, the high-salt, high-organic, and high-toxic wastewater is sent to the preheating system to exchange heat with the hot material from the reactor. The preheating system adopts a multi-stage heat exchanger. After the wastewater goes through the multi-stage preheating process, the temperature of the wastewater can reach 180-200℃, which reduces the temperature rise during the final heating and reduces the energy consumption of the operation compared to conventional wet oxidation processes.

[0032] Step 2: The heated high-salt, high-organic, and highly toxic wastewater, along with the oxidant, is fed into a wet oxidation device equipped with a solid catalyst. The temperature is gradually increased to the required reaction temperature for high-temperature treatment. The wet oxidation reaction temperature is 200-260℃, with the temperature reaching approximately 200-240℃ in the low-temperature zone and 220-260℃ in the high-temperature zone. The reaction pressure in the wet oxidation reactor is 2-8 MPa. The reaction temperature and pressure can be adjusted in real time according to the raw water concentration and the reaction process. The reaction residence time is 40-60 minutes, and air is used as the oxidant during the reaction.

[0033] Solid catalysts are selected from multi-metal oxide composite catalysts, mainly utilizing the structure, morphology, and electronic state of various rare earth metal oxides (FeO, MnO, CeO, CuO, ZnO) to ensure sufficient contact between them and the support, increasing the catalyst's surface area and active sites, resulting in higher catalytic activity and efficient degradation of organic pollutants. Simultaneously, this approach helps reduce metal ion dissolution, extends catalyst lifespan, and saves costs, as detailed below:

[0034] Mn-based oxides possess a variety of oxidation states and crystal planes, exhibiting unique redox properties. They can be converted into Mn(n) oxides. 4+ / Mn 3+ The oxidation-reduction cycle and oxygen activation process between the oxygen atoms facilitate oxygen transfer, which is beneficial for the utilization of surface oxygen and the activation of gaseous oxygen during wet oxidation.

[0035] Cu-based composite oxides have high catalytic activity, but they suffer from copper ion loss after repeated use. However, their catalytic activity can be improved when they interact with other metals, and the amount of dissolution is extremely small.

[0036] Fe-based oxides exhibit excellent oxidizing properties, high selectivity, and high reaction rates. Fe-based oxide catalysts possess stable physicochemical properties, exhibit low sensitivity to moisture and even water vapor, and are non-biotoxic, making them widely used in the field of catalytic oxidation.

[0037] Zn-based oxides primarily utilize the active sites on the surface of zinc oxide molecules to promote chemical reactions between reactant molecules. They possess high surface area and porosity, good chemical and thermal stability, and the crystal structure of zinc oxide catalysts is highly controllable, allowing for adjustment according to the needs of the oxidation reaction system.

[0038] Ce, as an electronic promoter, can interact with other metals to promote the generation of active metal sites and the production of active free radicals from other active oxidants, thereby improving the catalytic performance of the catalyst. Simultaneously, the doping of metal ions can cause changes in the lattice structure of Ce-based catalysts, thereby increasing the mobility of oxygen anions and enhancing the oxygen storage and release capabilities of Ce-based catalysts, effectively improving their catalytic performance.

[0039] (1) CuO-MnO-CeO type catalyst

[0040] The addition of Mn promotes the dispersion of Cu species, resulting in more uniform grain size and improved catalyst activity and selectivity. The introduction of Ce can adjust the ratio of Cu and Mn ions on the catalyst surface. The synergistic effect between Cu, Mn, and Ce can improve catalytic activity, and the amount of dissolution is minimal. CuO-MnO-CeO type catalysts use compounds with special regular structures as precursors, and the interaction between the elements forming composite oxides significantly improves the catalyst's catalytic performance and stability.

[0041] (2) FeO-CuO-MnO type catalyst

[0042] Loading both iron and copper onto a support simultaneously can improve the stability of iron and the activity of copper. The addition of copper can not only enhance the catalytic activity of iron-based catalysts but also reduce their dependence on pH, keeping the pH of the treated wastewater within a milder range, thus reducing the amount of reagents needed and the corrosion of equipment. In addition, the addition of manganese can transform the catalyst surface from crystalline to amorphous. FeO-CuO-MnO catalysts have high surface area, thermal stability, mechanical strength, and chemical stability, resulting in strong catalytic properties.

[0043] (3) CuO-ZnO-CeO type catalyst

[0044] The working principle of CuO-ZnO-CeO catalyst is based on the adsorption and catalytic effect of zinc oxide on reactants, which provides active sites for the reaction. The addition of copper oxide plays a role in regulating the reaction rate and improving the stability of the catalyst. The incorporation of Ce can effectively improve the dispersion of copper and zinc metals on the support surface. CuO-ZnO-CeO catalyst has strong activity.

[0045] TiO2 was chosen as the catalyst support because it exhibits good stability under both acidic and alkaline conditions and is relatively inexpensive. The metal oxides coated on the TiO2 support result in a catalyst with strong catalytic activity and good resistance to leaching, enabling efficient degradation of organic pollutants in wastewater.

[0046] Step 3: During the wet oxidation reaction, the organic matter in the wastewater is oxidized. The gas-liquid mixture flowing out of the wet oxidation tower contains a high concentration of gas and vapor. Directly entering the heat exchanger may cause excessive pressure on the equipment, thereby damaging the heat exchanger or other related equipment. Gas-liquid separation can control the fluid pressure entering the heat exchanger and protect the equipment from damage.

[0047] Simultaneously, it ensures the high purity of the fluid entering the heat exchanger, preventing blockage or decreased heat transfer efficiency. The high-temperature material discharged from the wet oxidation tower is separated by a high-pressure gas-liquid separator. Both the gas and liquid phases sequentially enter a multi-stage heat exchanger to preheat the feed liquid into the wet oxidation tower, forming a reaction cycle. This reduces the temperature rise during final heating, achieving heat recovery during the reaction process and lowering energy consumption and costs. The gas and liquid phases entering the multi-stage heat exchanger then form a gas-liquid mixture again.

[0048] Step 4: After heat exchange, the gas-liquid mixture enters a low-pressure gas-liquid separator for further gas-liquid separation. The resulting liquid phase enters a deep treatment unit for further processing or is discharged. The deep treatment unit includes biochemical treatment technologies such as A / O, SBR, and MBR to further remove organic pollutants from the wastewater. The resulting gas phase enters the raw wastewater storage tank, realizing the recovery and utilization of pressure and residual oxygen in the gas after the reaction. The scale of high-salt, high-organic, and high-toxicity organic wastewater under high-temperature conditions is mainly a composite scale composed of calcium carbonate and magnesium carbonate. The CO2 volume percentage in the reaction gas phase of the wet oxidation tower is about 20%-80%. The CO2-rich reaction gas is introduced into the raw water storage tank. The CO2 reacts with the carbonates in the wastewater to generate bicarbonates, which can effectively prevent scaling and clogging, thus achieving the conditioning and modification of the raw wastewater and ensuring stable process operation.

[0049] In practical applications, this invention can be used to treat wastewater from pesticides, pharmaceuticals, coking, dyes, printing and dyeing, petrochemicals, and leather.

[0050] Example 1

[0051] A pesticide company generates mixed wastewater containing pesticide intermediates during its production process. The main organic compounds are o-nitrophenol and p-hydroxyphenoxypropionic acid, and the wastewater volume is 100 m³. 3 / d, with an influent COD concentration of 98000 mg / L and a B / C ratio of 0.2, deep oxidation is performed using the improved wet oxidation reaction technology provided by this invention, specifically including the following steps:

[0052] 1. After conditioning and modification, the high-salt, high-organic, and highly toxic wastewater in the raw water storage tank is sent to the preheating system to exchange heat with the hot material from the reactor. It is gradually heated to 200℃ through a multi-stage heat exchanger.

[0053] 2. The pressurized and heated high-salt, high-organic, and highly toxic wastewater is fed together with the oxidant into a wet oxidation device containing a solid catalyst for high-temperature treatment. The temperature is raised to 220°C in the low-temperature zone of the wet oxidation reactor and to 260°C in the high-temperature zone. The pressure inside the reactor is 8 MPa, the oxidant is compressed air, and the catalyst is a CuO-MnO-CeO supported type. The catalyst dosage accounts for 2.5% of the wastewater mass, and the catalyst reacts with the oxidant for 60 minutes.

[0054] 3. During the reaction, the organic matter in the wastewater is oxidized, and the reaction releases a large amount of heat to keep the temperature of the mixed liquid constant. The high-temperature and high-pressure material flowing out of the reactor is processed by the high-pressure gas-liquid separation device and then enters the multi-stage heat exchanger to be cooled. The heat generated during the reaction is recovered and reused for wastewater preheating.

[0055] 4. After cooling, the liquid enters the low-pressure gas-liquid separation device. The resulting liquid phase enters the deep treatment unit for further treatment or is discharged. The resulting gas phase enters the raw water storage tank. The pressure and residual oxygen in the gas after the reaction are recovered and reused. At the same time, the raw wastewater is conditioned and modified to reduce the risk of scaling in the system.

[0056] The COD concentration of the treated organic wastewater was 7336 mg / L, the COD removal rate reached 92.51%, and the B / C ratio of the effluent was 0.41.

[0057] Example 2

[0058] A chemical company producing coatings and resins discharged high-concentration organic wastewater with a COD concentration of 80,000 mg / L and a wastewater volume of 125 m³. 3 With a B / C ratio of 0.24, deep oxidation is performed using the improved wet oxidation reaction technology provided by this invention, specifically including the following steps:

[0059] 1. After conditioning and modification, the high-salt, high-organic, and highly toxic wastewater in the raw water storage tank is sent to the preheating system to exchange heat with the hot material from the reactor. It is gradually heated to 200℃ through a multi-stage heat exchanger.

[0060] 2. The pressurized and heated high-salt, high-organic, and highly toxic wastewater is fed together with the oxidant into a wet oxidation device containing a solid catalyst for high-temperature treatment. The temperature is raised to 220°C in the low-temperature zone of the wet oxidation reactor and to 260°C in the high-temperature zone. The pressure inside the reactor is 7 MPa, the oxidant is compressed air, and the catalyst is a FeO-CuO-MnO supported type. The catalyst dosage accounts for 2% of the wastewater mass, and the catalyst reacts with the oxidant for 50 minutes.

[0061] 3. During the reaction, the organic matter in the wastewater is oxidized, and the reaction releases a large amount of heat to keep the temperature of the mixed liquid constant. The high-temperature and high-pressure material flowing out of the reactor is processed by the high-pressure gas-liquid separation device and then enters the multi-stage heat exchanger to be cooled. The heat generated during the reaction is recovered and reused for wastewater preheating.

[0062] 4. After cooling, the liquid enters the low-pressure gas-liquid separation device. The resulting liquid phase enters the deep treatment unit for further treatment or is discharged. The resulting gas phase enters the raw water storage tank. The pressure and residual oxygen in the gas after the reaction are recovered and reused. At the same time, the raw wastewater is conditioned and modified to reduce the risk of scaling in the system.

[0063] The tested organic wastewater had a COD concentration of 7200 mg / L, a COD removal rate of 91%, and a B / C ratio of 0.4.

[0064] Example 3

[0065] A petrochemical company generates waste alkaline solution with a COD concentration of 67,500 mg / L and a wastewater volume of 1.5 m³. 3 / h, deep oxidation is performed using the improved wet oxidation reaction technology provided by this invention, specifically including the following steps:

[0066] 1. After conditioning and modification, the high-salt, high-organic, and highly toxic wastewater in the raw water storage tank is sent to the preheating system to exchange heat with the hot material from the reactor. It is gradually heated to 200℃ through a multi-stage heat exchanger.

[0067] 2. The pressurized and heated high-salt, high-organic, and highly toxic wastewater is fed together with the oxidant into a wet oxidation device containing a solid catalyst for high-temperature treatment. The temperature is raised to 220°C in the low-temperature zone of the wet oxidation reactor and to 250°C in the high-temperature zone. The pressure inside the reactor is 7 MPa, the oxidant is compressed air, and the catalyst is FeO-CuO-MnO supported type. The catalyst dosage accounts for 2% of the wastewater mass, and the catalyst reacts with the oxidant for 45 minutes.

[0068] 3. During the reaction, the organic matter in the wastewater is oxidized, and the reaction releases a large amount of heat to keep the temperature of the mixed liquid constant. The high-temperature and high-pressure material flowing out of the reactor is processed by the high-pressure gas-liquid separation device and then enters the multi-stage heat exchanger to be cooled. The heat generated during the reaction is recovered and reused for wastewater preheating.

[0069] 4. After cooling, the liquid enters the low-pressure gas-liquid separation device. The resulting liquid phase enters the deep treatment unit for further treatment or is discharged. The resulting gas phase enters the original wastewater storage tank. The pressure and residual oxygen in the gas after the reaction are recovered and utilized. At the same time, the original wastewater is conditioned and modified to reduce the risk of scaling in the system.

[0070] The tested organic wastewater had a COD concentration of 5200 mg / L, a COD removal rate of 92.3%, and a B / C ratio of 0.4.

[0071] The above embodiments are the best implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A wastewater treatment method based on a modified wet oxidation reaction, characterized in that, Includes the following steps: Step 1: After the wastewater has been treated with conditioning and modification, it is preheated and heated using a multi-stage heat exchanger; the multi-stage heat exchanger consists of several heat exchangers connected in series. Step 2: The preheated wastewater and oxidant are fed together into a wet oxidation tower containing a solid catalyst, and the temperature is gradually increased to the required reaction temperature to carry out the wet oxidation reaction; the solid catalyst is a metal oxide supported catalyst, and the metal oxide is coated on a support; the metal combination supported on the support includes CuO-MnO-CeO, FeO-CuO-MnO or CuO-ZnO-CeO, and the support is a TiO2 support; Step 3: Separate the gas-liquid mixture flowing out of the wet oxidation tower. The separated gas and liquid phases enter the multi-stage heat exchanger described in Step 1. After exchanging heat with the wastewater in Step 1, the wastewater is preheated and the gas and liquid phases form a gas-liquid mixture again. Step 4: The gas-liquid mixture after heat exchange is separated again. The separated gas phase enters the wastewater from Step 1 to condition and modify the wastewater, while the separated liquid phase is further treated or discharged.

2. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 1, the wastewater is wastewater from the pesticide, pharmaceutical, coking, dye, printing and dyeing, petrochemical or leather industries with an influent COD concentration of less than 100,000 mg / L.

3. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 1, the wastewater temperature reaches 180-200℃ after preheating.

4. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 2, the oxidant is selected from air; the temperature of the wet oxidation reaction is 200-260℃, the reaction pressure is 2-8MPa, and the reaction residence time is 40-60min.

5. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 2, the gradual heating involves dividing the wet oxidation tower into a low-temperature reaction zone and a high-temperature reaction zone. The temperature in the low-temperature reaction zone is 200-240℃, and the temperature in the high-temperature zone is 220-260℃. Wastewater enters the wet oxidation tower and passes through the low-temperature zone and the high-temperature zone in sequence, gradually heating up to the final reaction temperature.

6. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 3, the gas-liquid separation is performed using a high-pressure gas-liquid separator.

7. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 4, the gas-liquid separation is performed using a low-pressure gas-liquid separator.

8. The wastewater treatment method based on a modified wet oxidation reaction according to claim 1, characterized in that, In step 4, the advanced treatment includes using A / O, SBR, or MBR biochemical treatment technologies to further remove organic pollutants from the wastewater.

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