Method for treating phenolic wastewater by UV / H2O2 pretreatment coupled wet catalytic oxidation combined process

Abstract

The invention discloses a method for treating phenolic wastewater through a UV / H2O2 pretreatment coupling wet catalytic oxidation combined process, and belongs to the technical field of industrial wastewater treatment.The method is characterized by comprising the following steps that S1, wastewater is introduced into a UV / H2O2 reactor, H2O2 is introduced, and wastewater pretreatment is conducted under ultraviolet; s2, the pretreated wastewater passes through a heat exchanger and then enters a wet catalytic oxidation reaction tower for deep treatment; and S3, carrying out gas-liquid separation on the wastewater subjected to advanced treatment, cooling high-temperature water in a heat exchanger, feeding the cooled high-temperature water into a sedimentation tank, cooling, carrying out biochemical treatment, and discharging the cooled high-temperature water after reaching the standard. According to the method, mild pretreatment is carried out through UV / H2O2, and cooperative reinforcement is carried out with subsequent wet catalytic oxidation, so that efficient utilization of energy and advanced removal of pollutants are realized; the purpose of efficient, mild and low-cost phenolic aldehyde wastewater treatment is achieved.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to a method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process. Background Technology

[0002] Phenolic resin, a high-molecular-weight compound formed by the polymerization of phenol and formaldehyde through a condensation reaction under the action of a catalyst, occupies a key basic material position in modern industrial systems. It is widely used in numerous industrial fields such as plastic molding, coating preparation, and wood adhesives, providing crucial support for the development of these industries, greatly promoting the progress of related industries and improving product quality, playing an indispensable role in both industrial production and daily life. With the continuous development of industry, the production and consumption of phenolic resin are also continuously increasing, and research on its production and application is becoming increasingly in-depth, with its application prospects in various fields becoming increasingly broad. However, the wastewater problem generated during the production of phenolic resin has gradually become a significant factor restricting its further development.

[0003] Currently, common methods for treating phenolic wastewater include biological methods, adsorption methods, advanced oxidation methods, and incineration. Biological methods utilize the metabolic activity of microorganisms to decompose organic matter in wastewater; due to their low cost, they are widely used in some wastewater treatment scenarios. Adsorption methods, such as activated carbon adsorption, transfer pollutants from wastewater to the adsorbent through adsorption, thereby purifying the wastewater. The UV / H2O2 process in advanced oxidation methods utilizes the strong oxidizing properties of hydroxyl radicals to oxidize organic matter, achieving the purpose of pollutant removal. Wet catalytic oxidation (CWAO) can deeply degrade organic matter, improving wastewater treatment efficiency to some extent. These methods can treat phenolic wastewater to varying degrees, providing multiple pathways to solve the phenolic wastewater problem.

[0004] However, these existing treatment methods have significant drawbacks. Biological methods are poorly tolerant of high-concentration phenolic wastewater, easily leading to microbial poisoning and poor treatment results. Adsorption methods merely transfer pollutants from wastewater to the adsorbent, requiring subsequent treatment of the adsorbent to prevent secondary pollution. In the UV / H2O2 process within the single advanced oxidation process, for high-concentration, high-color phenolic wastewater, the ultraviolet-absorbing substances in the wastewater severely block ultraviolet light penetration, resulting in a sharp decline in photolysis efficiency and low H2O2 utilization. While wet catalytic oxidation (CWAO) can deeply degrade organic matter, it requires high temperature and pressure conditions, resulting in high energy consumption and demanding equipment requirements, limiting its industrial application. Therefore, developing a phenolic wastewater treatment technology that can improve treatment efficiency, optimize reaction conditions, and reduce costs is urgently needed. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process. This method uses UV / H2O2 for mild pretreatment, which is synergistically enhanced with subsequent wet catalytic oxidation to achieve efficient energy utilization and deep removal of pollutants, thus achieving the goal of efficient, mild, and low-cost treatment of phenolic wastewater.

[0006] This invention provides a method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process, employing the following technical solution: A method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation process includes the following steps: S1. The wastewater is introduced into the UV / H2O2 reactor and H2O2 is introduced to pretreat the wastewater under ultraviolet light. S2. The pretreated wastewater is passed through a heat exchanger and then enters a wet catalytic oxidation reaction tower for further treatment. S3. After the wastewater undergoes gas-liquid separation, the high-temperature water enters a heat exchanger to cool down before entering a sedimentation tank. After cooling and biochemical treatment to meet the standards, it is discharged.

[0007] By adopting the above technical solution, this application first introduces wastewater into a UV / H2O2 reactor. The ultraviolet light source can excite hydrogen peroxide to generate a large amount of -OH (hydroxyl radicals). -OH has strong oxidizing properties (its oxidation potential is 2.8V), which can quickly destroy the long-chain structure of phenolic resin, degrading large molecular organic matter into easily oxidizable substances such as small molecular carboxylic acids and aldehydes. At the same time, it decomposes large molecular toxic substances into small groups of non-toxic substances, reducing the toxicity of wastewater and creating conditions for subsequent wet catalytic oxidation. Moreover, after UV / H2O2 reaction treatment, the COD content in the wastewater is significantly reduced. During wet catalytic oxidation, a mild temperature and pressure can be used to completely oxidize small molecular organic matter into carbon dioxide and water, achieving deep removal of COD and phenolic substances. Therefore, UV / H2O2 pretreatment reduces the organic matter load of wet catalytic oxidation, allowing subsequent reactions to be carried out at lower temperatures and pressures, reducing energy consumption. At the same time, the small molecular organic matter generated by pretreatment is more easily adsorbed and activated by the catalyst in wet catalytic oxidation, improving the efficiency of wet catalytic oxidation and reducing the cost of phenolic wastewater treatment.

[0008] In a preferred embodiment, the amount of H2O2 added is 0.5-2 times the mass of COD in the wastewater.

[0009] By adopting the above technical solution and limiting the amount of H2O2 added to the above range, it is possible to ensure that there are enough raw materials to generate hydroxyl radicals, thus avoiding the reaction from stopping midway or the incomplete degradation of macromolecules due to insufficient oxidant. At the same time, it is also possible to effectively avoid the impact of adding too much hydrogen peroxide on subsequent biochemical treatment.

[0010] In a preferred embodiment, the wavelength of the ultraviolet light source is 254 nm.

[0011] By adopting the above technical solution, when the wavelength of the ultraviolet light source is 254nm, the efficiency of hydrogen peroxide in generating hydroxyl radicals is the highest, thereby improving the efficiency of wastewater pretreatment.

[0012] In a preferred embodiment, the effective radiation dose of the ultraviolet light is 10,000-50,000 mJ / cm². 2 The radiation dose is 3-15 W / L, and more preferably, the effective ultraviolet radiation dose is 15000-30000 mJ / cm². 2 .

[0013] In a preferred embodiment, the wastewater pretreated in step S2 has a BOD5 / COD ratio ≥ 0.5.

[0014] By adopting the above technical solution, when the BOD5 / COD of the wastewater after deep treatment is ≥0.5, it indicates that the large molecules and difficult-to-degrade toxic substances in the wastewater are decomposed into small molecules and easily degradable organic matter, thereby increasing the BOD5 / COD ratio and improving the biodegradability (generally, BOD5 / COD <0.3 is considered difficult to biodegrade).

[0015] In a preferred embodiment, in step S2, the reaction temperature is 110-200℃, the pressure is 1-3 MPa, and the reaction time is 60-120 min.

[0016] In a preferred embodiment, the gas flow rate of the wet catalytic oxidation reaction tower is 1-2 times the mass ratio of COD in the pretreated wastewater.

[0017] In a preferred embodiment, in step S1, before the wastewater is introduced into the UV / H2O2 reactor, the pH of the wastewater is adjusted to 3-5 before it is introduced into the UV / H2O2 reactor.

[0018] By adopting the above technical solution, adjusting the pH of the wastewater to 3-5 before it enters the UV / H2O2 reactor allows the hydrogen peroxide to efficiently absorb ultraviolet light, thereby efficiently and controllably decomposing and generating hydroxyl radicals, reducing the ineffective loss of hydrogen peroxide, and ensuring a sufficient concentration of hydroxyl radicals. Furthermore, in a weakly acidic environment, hydroxyl radicals can react with phenolic pollutants at a faster rate, thus improving degradation efficiency. The acidic environment also prevents the precipitation of metal ions in the wastewater, ensuring ultraviolet light penetration and facilitating the reaction between hydroxyl radicals and organic matter in the wastewater.

[0019] However, if the pH of the wastewater is below 3, the excessively acidic environment will induce hydrogen peroxide to undergo a non-photolytic self-decomposition reaction, causing it to be ineffectively consumed before entering the effective photolysis pathway. This reduces the total amount of hydrogen peroxide available for generating hydroxyl radicals and lowers the apparent free radical generation rate. In order to achieve the expected treatment effect, more hydrogen peroxide needs to be added, which leads to an increase in treatment costs.

[0020] In a preferred embodiment, the COD content in the wastewater does not exceed 60,000 mg / L.

[0021] In a preferred embodiment, in step S3, the high-temperature water is cooled to 50-80°C and then enters the sedimentation tank.

[0022] In summary, the present invention has the following beneficial effects: This application employs a UV / H2O2 reaction, where hydrogen peroxide is converted into hydroxyl radicals under ultraviolet light, degrading large organic molecules in wastewater into easily oxidizable substances such as small-molecule carboxylic acids and aldehydes. This simultaneously reduces the toxicity of the wastewater, providing a strong guarantee for subsequent wet catalytic oxidation to proceed under mild reaction conditions. This significantly reduces the treatment cost of phenolic wastewater and also significantly increases its treatment efficiency. Furthermore, during the recycling process, the high temperature after wet catalytic oxidation treatment, when entering the heat exchanger, allows the accumulated heat to heat the wastewater before it enters the wet catalytic oxidation reaction tower, thereby reducing the treatment cost of the wet catalytic oxidation reaction tower. Attached Figure Description

[0023] Figure 1 This is a flowchart of the treatment process for phenolic wastewater in Example 1 of this application. Detailed Implementation

[0024] The following combination Figure 1 The wastewater treatment flow chart further illustrates this invention in detail. All reagents, unless otherwise specified, are commercially available conventional reagent products. Example 1

[0025] A method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process, combining Figure 1 It includes the following steps: The COD concentration of a certain phenolic wastewater is 23000 mg / L, the phenolic substance concentration is 4600 mg / L, the pH is 6.5, and the BOD5 / COD ratio is 0.22. S1. The wastewater from the raw water tank is pumped into a pH adjustment tank, and sulfuric acid is added to adjust the pH to 3. Then, it is transferred to a UV / H2O2 reactor. The reactor is filled with 30% H2O2 (the amount of H2O2 is 0.5 times the COD mass of the wastewater). Pretreatment of the wastewater is performed under ultraviolet light with a wavelength of 254 nm and an effective radiation dose of 15000 mJ / cm². 2 The radiation dose was 5 W / L, the pretreatment time was 60 min, and the COD in the treated wastewater was 11000 mg / L and the phenolic substances were 2800 mg / L. S2. The pretreated wastewater is passed through a plate heat exchanger and then enters a wet catalytic oxidation reactor for further treatment under the action of a catalyst. Oxygen is introduced into the wet catalytic oxidation reactor at a mass ratio of 1:1 to the COD in the pretreated wastewater. The wet catalytic oxidation reactor is heated to 110℃ and reacted for 120 minutes at a pressure of 1MPa. After the reaction, the COD in the wastewater is measured to be 1100mg / L, the phenolic substances are 0.30mg / L, and the BOD5 / COD ratio is 0.51. S3. The high-temperature water from the wet catalytic oxidation tower enters the gas-liquid separator. The gas separated from the gas-liquid separator is collected, purified, and then discharged. The high-temperature water separated from the gas-liquid separator enters the plate heat exchanger to exchange heat with the next batch of wastewater pretreated from the UV / H2O2 reactor. After the high-temperature water is cooled to 50°C in the plate heat exchanger, it enters the sedimentation tank for cooling and then enters the aerobic moving bed biofilm reactor for biochemical treatment. Under the action of microorganisms attached to the suspended biological packing, the organic matter is efficiently degraded and nitrified, and the COD is reduced to 85 mg / L and the phenolic substances are 0.27 mg / L, meeting the emission standards. The next batch of reactions repeats the operation of step S1. When the wastewater pretreated from the UV / H2O2 reactor is heated to between 90-110°C in the plate heat exchanger, it can enter the wet catalytic oxidation reaction tower. At this time, the heater in the wet catalytic oxidation reaction tower does not need to be started. The high-temperature water reacted from the wet catalytic oxidation reaction tower repeats the step S3. Example 2

[0026] A method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation process includes the following steps: The COD concentration of a certain phenolic wastewater is 41,000 mg / L, the phenolic substance concentration is 5,900 mg / L, the pH is 6.6, and the BOD5 / COD ratio is 0.19. S1. The wastewater from the raw water tank is pumped into a pH adjustment tank, and sulfuric acid is added to adjust the pH to 5. Then, it is transferred to a UV / H2O2 reactor. The reactor is filled with 30% H2O2 (the amount of H2O2 is 1.3 times the COD mass of the wastewater). Pretreatment of the wastewater is performed under ultraviolet light with a wavelength of 254 nm and an effective radiation dose of 20000 mJ / cm². 2 The radiation dose was 10W / L, the pretreatment time was 30min, and the COD in the treated wastewater was 21000mg / L and the phenolic substances were 3600mg / L. S2. The pretreated wastewater is passed through a plate heat exchanger and then enters a wet catalytic oxidation reactor for further treatment under the action of a catalyst. Oxygen is introduced into the wet catalytic oxidation reactor at a mass ratio of 1.5:1 to the COD in the pretreated wastewater. The wet catalytic oxidation reactor is heated to 150℃ and reacted for 90 minutes at a pressure of 2MPa. After the reaction, the COD in the wastewater is measured to be 1680mg / L, the phenolic substances are 0.27mg / L, and the BOD5 / COD ratio is 0.53. S3. The high-temperature water from the wet catalytic oxidation tower enters the gas-liquid separator. The gas separated from the gas-liquid separator is collected, purified, and then discharged. The high-temperature water separated from the gas-liquid separator enters the plate heat exchanger, where it exchanges heat with the next batch of wastewater pretreated from the UV / H2O2 reactor. After the high-temperature water is cooled to 80°C in the plate heat exchanger, it enters the sedimentation tank for cooling and then enters the aerobic moving bed biofilm reactor for biochemical treatment. Under the action of microorganisms attached to the suspended biological packing, the organic matter is efficiently degraded and nitrified, and the COD is reduced to 78 mg / L and the phenolic substances to 0.25 mg / L, meeting the emission standards. The next batch of reactions repeats the operation of step S1. When the wastewater pretreated from the UV / H2O2 reactor is heated to between 110-150°C in the plate heat exchanger, it can enter the wet catalytic oxidation reaction tower. At this time, the heater in the wet catalytic oxidation reaction tower does not need to be started. The high-temperature water reacted from the wet catalytic oxidation reaction tower repeats the step S3. Example 3

[0027] A method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation process includes the following steps: The COD concentration of a certain phenolic wastewater is 58,000 mg / L, the phenolic substance concentration is 7,100 mg / L, the pH is 6.4, and the BOD5 / COD ratio is 0.21. S1. The wastewater from the raw water tank is pumped into a pH adjustment tank, and sulfuric acid is added to adjust the pH to 5. Then, it is transferred to a UV / H2O2 reactor. The reactor is filled with 30% H2O2 (the amount of H2O2 is twice the COD mass of the wastewater). Pretreatment of the wastewater is performed under ultraviolet light with a wavelength of 254 nm and an effective radiation dose of 30,000 mJ / cm². 2 The radiation dose was 15W / L, the pretreatment time was 45min, and the COD in the treated wastewater was 26100mg / L and the phenolic substances were 3905mg / L. S2. The pretreated wastewater is passed through a plate heat exchanger and then enters a wet catalytic oxidation reactor for further treatment under the action of a catalyst. Oxygen is introduced into the wet catalytic oxidation reactor at a mass ratio of 2:1 to COD in the pretreated wastewater. The wet catalytic oxidation reactor is heated to 200℃ and reacted for 60 minutes at a pressure of 3MPa. After the reaction, the COD in the wastewater is measured to be 1560mg / L, the phenolic substances are 0.28mg / L, and the BOD5 / COD ratio is 0.5. S3. The high-temperature water from the wet catalytic oxidation tower enters the gas-liquid separator. The gas separated from the gas-liquid separator is collected, purified, and then discharged. The high-temperature water separated from the gas-liquid separator enters the plate heat exchanger, where it exchanges heat with the next batch of wastewater pretreated from the UV / H2O2 reactor. After the high-temperature water is cooled to 80°C in the plate heat exchanger, it enters the sedimentation tank for cooling and then enters the aerobic moving bed biofilm reactor for biochemical treatment. Under the action of microorganisms attached to the suspended biological packing, the organic matter is efficiently degraded and nitrified, and the COD is reduced to 70 mg / L and the phenolic substances to 0.25 mg / L, meeting the emission standards. The next batch of reactions repeats the operation of step S1. When the wastewater pretreated from the UV / H2O2 reactor is heated to between 150-200°C in the plate heat exchanger, it can enter the wet catalytic oxidation reaction tower. At this time, the heater in the wet catalytic oxidation reaction tower does not need to be started. The high-temperature water reacted from the wet catalytic oxidation reaction tower repeats the step S3.

[0028] Comparison 1

[0029] The COD of a certain phenolic wastewater is 23000 mg / L, the phenolic substances are 4600 mg / L, the pH is 6.5, and the BOD5 / COD ratio is 0.22. A method for treating phenolic wastewater using UV / H2O2 includes the following steps: Wastewater from a raw water tank is pumped into a pH adjustment tank, sulfuric acid is added to adjust the pH to 3, and then the wastewater is transported to a UV / H2O2 reactor. A 30% concentration of H2O2 is added to the UV / H2O2 reactor, with the amount of H2O2 being 0.5 times the COD mass of the wastewater. The wastewater is pretreated under UV light with a wavelength of 254 nm for 150 minutes. After treatment, the COD in the wastewater is measured to be 10000 mg / L, and the phenolic substance concentration is 2700 mg / L. The calculated COD removal rate is 56.52%, the phenolic substance removal rate is 41.30%, and the biodegradable BOD5 / COD ratio is 0.30. The results demonstrate low oxidation efficiency and minimal improvement in biodegradability.

[0030] Comparative Example 2

[0031] The COD of a certain phenolic wastewater is 23000 mg / L, the phenolic substances are 4600 mg / L, the pH is 6.5, and the BOD5 / COD ratio is 0.22. A method for treating phenolic wastewater using wet catalytic oxidation is disclosed. Phenolic compounds are introduced into a wet catalytic oxidation reactor. Under the action of a catalyst, the wastewater is treated. Oxygen is introduced into the reactor, and the temperature is raised to 240°C. The reaction is carried out for 120 minutes at a pressure of 6 MPa. After the reaction, the COD in the wastewater was measured to be 4500 mg / L, and the phenolic compounds were 700 mg / L. The calculated COD removal rate was 80.43%, the phenolic compound removal rate was 84.78%, and the BOD5 / COD ratio was 0.35. This indicates that after catalytic oxidation under high temperature and pressure, the COD and phenolic compound content in the wastewater are significantly higher than the results of the combined UV / H2O2 and wet catalytic oxidation treatment in the embodiments of this application. This further demonstrates that the combined treatment method of this application can not only effectively reduce COD and phenolic compounds in wastewater but also reduce wastewater treatment costs.

[0032] Comparative Example 3

[0033] A method for treating phenolic wastewater using a UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process, using the same batch of wastewater as in Example 1, differs from Example 1 in that sulfuric acid is not added to adjust the pH of the wastewater in step S1, as detailed below: The COD concentration of a certain phenolic wastewater is 23000 mg / L, the phenolic substance concentration is 4600 mg / L, the pH is 6.5, and the BOD5 / COD ratio is 0.22. S1. Wastewater from the raw water tank is directly transferred to the UV / H2O2 reactor. The reactor is filled with 30% H2O2, the amount of which is 0.5 times the COD mass of the wastewater. Pretreatment of the wastewater is performed under ultraviolet light with a wavelength of 254nm and an effective radiation dose of 15000mJ / cm². 2 The radiation dose was 5 W / L, the pretreatment time was 60 min, and the COD in the treated wastewater was 18400 mg / L and the phenolic substances were 3450 mg / L. S2. The pretreated wastewater is passed through a plate heat exchanger and then enters a wet catalytic oxidation reaction tower for further treatment under the action of a catalyst. Oxygen is introduced into the wet catalytic oxidation reaction tower, and the tower is heated to 110°C. The reaction is carried out for 120 minutes at a pressure of 1 MPa. After the reaction, the COD in the wastewater is 4000 mg / L, the phenolic substances are 1 mg / L, and the BOD5 / COD ratio is 0.35. Step S3 was not performed.

[0034] The degradation rates of COD and phenolic substances in Comparative Example 3 and Example 1 show that acid treatment effectively removes COD and phenolic substances from the wastewater after pretreatment in step S1. This allows for a deeper reduction of COD and phenolic substances in the wastewater in step S2 at lower temperatures and pressures, resulting in wastewater with good biodegradability and low cost. In contrast, without acid treatment, Comparative Example 3 showed relatively high levels of COD and phenolic substances in both pretreatment and deep treatment. To improve the removal rate of COD and phenolic substances in the wastewater of Comparative Example 3, it is necessary to increase the reaction conditions by increasing pressure and temperature. This not only increases operating costs but also results in a lower removal rate of COD and phenolic substances compared to the present application.

[0035] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for treating phenolic wastewater by a combined process of UV / H2O2 pretreatment and wet catalytic oxidation, characterized in that, It comprises the following steps: S1, the wastewater is introduced into a UV / H2O2 reactor, H2O2 is introduced, and the wastewater is pretreated under ultraviolet light; S2, the pretreated wastewater is introduced into a wet catalytic oxidation reaction tower through a heat exchanger for deep treatment; S3, after the deep treated wastewater is subjected to gas-liquid separation, the high-temperature water is introduced into the heat exchanger for cooling, and then into a sedimentation tank, and is discharged after cooling and biochemical treatment.

2. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 1, characterized in that: The addition amount of H2O2 is 0.5-2 times of the mass of COD in the wastewater.

3. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 2, characterized in that: The wavelength of the ultraviolet light source is 254 nm.

4. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 3, characterized in that: The effective radiation dose of the ultraviolet light is 10000-50000 mJ / cm 2 , and the radiation dose is 3-15 W / L.

5. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 3, characterized in that: The BOD5 / COD of the pretreated wastewater in step S2 is greater than or equal to 0.

5.

6. The method for treating phenolic wastewater by a combined process of UV / H2O2 pretreatment and wet catalytic oxidation according to claim 1, characterized in that: In step S2, the reaction temperature is 110-200 DEG C, the pressure is 1-3 Mpa, and the reaction time is 60-120 min.

7. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 1, characterized in that: The mass ratio of the gas introduction amount of the wet catalytic oxidation reaction tower to the COD in the pretreated wastewater is 1-2.

8. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 1, characterized in that: In step S1, before the wastewater is introduced into the UV / H2O2 reactor, the pH of the wastewater is adjusted to 3-5, and then the wastewater is introduced into the UV / H2O2 reactor.

9. The method for treating phenolic wastewater by UV / H2O2 pretreatment coupled with wet catalytic oxidation combined process according to claim 1, characterized in that: The content of COD in the wastewater is not more than 60000 mg / L.

10. The method of treating phenolic wastewater by a combined process of UV / H2O2 pretreatment and wet catalytic oxidation according to claim 1, characterized in that: In step S3, the high-temperature water is cooled to 50-80 DEG C before being introduced into the sedimentation tank.

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