Advanced oxidation pretreatment system for HPPO wastewater

Abstract

The utility model relates to the technical field of wastewater treatment, in particular to an advanced oxidation pretreatment system for HPPO wastewater, which comprises an HP wastewater pretreatment unit, a PO wastewater pretreatment unit and an advanced oxidation unit. In the system provided by the utility model, the scheme design is carried out on the basis that the HP wastewater contains residual hydrogen peroxide and the pH value of the HP wastewater is acidic, the PO wastewater is alkaline, and the hydrogen peroxide can be subjected to decomposition reaction under the alkaline condition to generate oxygen and water, namely the decomposition of the residual hydrogen peroxide in the HP wastewater can be accelerated and the utilization rate of the hydrogen peroxide can be reduced if the wastewater is mixed and the acid is adjusted; the HP wastewater and the PO wastewater are respectively subjected to acid regulation operation while being subjected to split-flow pretreatment, so that the content of residual hydrogen peroxide in the HP wastewater is reserved to the maximum extent, and the dosage of a hydrogen peroxide reagent in the subsequent Fenton process is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a high-level oxidation pretreatment system for HPPO wastewater. Background Technique

[0002] Propylene oxide (PO) is an important organic chemical raw material and is the third largest organic chemical product after polypropylene and acrylonitrile in the output of propylene derivatives. It is mainly used in the production of polyether polyols, propylene glycol, polyurethane, surfactants, pesticide emulsifiers, etc. The technology of directly oxidizing propylene with hydrogen peroxide to prepare propylene oxide (HPPO process) is an advanced clean production process that has just been industrialized in recent years, which is economical, energy-saving, green and environmentally friendly. The wastewater of this process mainly comes from the hydrogen peroxide (HP) device and the propylene oxide (PO) device. The wastewater discharged from the HP device (referred to as HP wastewater for short) is mainly a refractory organic wastewater containing residual hydrogen peroxide and aromatic hydrocarbons. The wastewater discharged from the PO device (referred to as PO wastewater for short) mainly discharges alcohol, ether and salt-containing sewage (COD: about 30000mg / L, B / C < 0.15), and it is found through testing that the PO wastewater contains bactericidal substances 5-methyl-4,5,2-pyrazole, 3-methyl-1H-1,2,4-triazole and triazole. According to consulting relevant technical literature, the tolerance dose of microorganisms in the sewage treatment device to bactericides does not exceed 50ppm, and in actual application, the growth inhibition dose of bactericides to microorganisms is below 10ppm. Therefore, the biodegradability of HPPO wastewater is poor. In order to be able to be discharged into the biological advanced treatment link of sewage treatment subsequently, effective pretreatment is an urgent problem to be solved in the current HPPO wastewater treatment.

[0003] Chinese patent document CN215946853U discloses a combined treatment system for HPPO wastewater and hydrogen peroxide wastewater. This system combines HPPO wastewater and hydrogen peroxide wastewater and uses the peroxide in the hydrogen peroxide wastewater to carry out a catalytic oxidation reaction under acidic catalytic conditions, which can not only reduce the organic matter in the HPPO wastewater, improve the biodegradability of the wastewater, but also greatly reduce the peroxide concentration in the hydrogen peroxide wastewater, realize "treating waste with waste", and meet the requirements for entering the sewage treatment plant. However, whether it is the Fenton oxidation pretreatment or the reuse of hydrogen peroxide wastewater, its essence is that the Fenton method is used to oxidize and remove the organic matter in the HPPO wastewater. This method still has the defects of slow reaction rate and low utilization rate of H2O2 and needs further improvement. Content of the Utility Model

[0004] Therefore, the technical problem to be solved by the utility model is to overcome the defect of low utilization rate of H2O2 in the existing catalytic oxidation of HPPO wastewater, so as to provide a high-level oxidation pretreatment system for HPPO wastewater to solve the above problems.

[0005] To achieve the above object, the present utility model provides the following technical solutions:

[0006] An advanced oxidation pretreatment system for HPPO wastewater, the system comprising an HP wastewater pretreatment unit, a PO wastewater pretreatment unit, and an advanced oxidation unit; wherein, the HP wastewater pretreatment unit includes a flotation tank and a first acid adjustment tank connected in sequence; the PO wastewater pretreatment unit includes a second acid adjustment tank and a catalyst dosing tank connected in sequence; the advanced oxidation unit includes a catalytic oxidation tank connected to the wastewater outlets of both the HP wastewater pretreatment unit and the PO wastewater pretreatment unit, and a neutralization tank and a solid-liquid separation tank connected in sequence to the water outlet of the catalytic oxidation tank.

[0007] Preferably, an oil skimmer is provided at the top of the flotation tank.

[0008] Preferably, an ultra-fine bubble generator is provided at the bottom of the flotation tank.

[0009] Preferably, an on-line pH meter and an acid addition device are provided in both the first acid adjustment tank and the second acid adjustment tank.

[0010] Preferably, a catalyst dosing device is provided in the catalyst dosing tank to provide the catalyst (Fe 2+ ) required for the reaction.

[0011] Preferably, a stirring device is further provided in the first acid adjustment tank, the second acid adjustment tank, and the catalyst dosing tank.

[0012] Preferably, a flow regulating valve is provided at the wastewater outlets of both the HP wastewater pretreatment unit and the PO wastewater pretreatment unit.

[0013] Preferably, an oxidant dosing device, an ultrasonic stirring device, and a channel type medium pressure ultraviolet reactor assembly are provided in the catalytic oxidation tank.

[0014] Preferably, an on-line pH meter, an alkali addition device, and a mechanical turbine flocculation device are provided in the neutralization tank.

[0015] Preferably, the solid-liquid separation tank is an inclined plate sedimentation tank.

[0016] The technical solution of the present utility model has the following advantages:

[0017] 1. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, the system includes an HP wastewater pretreatment unit, a PO wastewater pretreatment unit and an advanced oxidation unit; wherein, the HP wastewater pretreatment unit includes a flotation tank and a first acid adjustment tank connected in sequence; the PO wastewater pretreatment unit includes a second acid adjustment tank and a catalyst dosing tank connected in sequence; the advanced oxidation unit includes a catalytic oxidation tank connected to the wastewater outlets of both the HP wastewater pretreatment unit and the PO wastewater pretreatment unit, and a neutralization tank and a solid-liquid separation tank connected in sequence to the water outlet of the catalytic oxidation tank. In the system provided by the present utility model, based on the fact that the HP wastewater contains residual hydrogen peroxide and its pH value is acidic, and the pH value of the PO wastewater is alkaline, and hydrogen peroxide will decompose under alkaline conditions to generate oxygen and water, that is, if the wastewater is mixed and then the acid is adjusted, the decomposition of the residual hydrogen peroxide in the HP wastewater will be accelerated. This technical solution designs the scheme from the perspective of reducing the utilization rate of hydrogen peroxide. While pretreating the HP wastewater and the PO wastewater separately by diversion, the acid adjustment operation is carried out respectively, which helps to retain the content of residual hydrogen peroxide in the HP wastewater to the greatest extent and saves the dosage of hydrogen peroxide reagent in the subsequent Fenton process.

[0018] 2. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, a micro-nano bubble generator is arranged at the bottom of the flotation tank to cooperate with the oil skimmer arranged at the top to remove the oil in the wastewater.

[0019] 3. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, an on-line pH meter is arranged in the first acid adjustment tank and the second acid adjustment tank to control the stability of the reaction pH value.

[0020] 4. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, an ultrasonic stirring device and a channel type medium pressure ultraviolet reactor assembly are simultaneously arranged in the catalytic oxidation tank. The ultrasonic-ultraviolet synergistic enhanced Fenton reaction is adopted to uniformly mix the wastewater while accelerating the regeneration of reduced Fe 2+ , improving the production rate of ·OH, increasing the utilization rate of hydrogen peroxide, reducing the sludge production amount and the dosage of Fe 2+ catalyst and hydrogen peroxide oxidant, and enhancing the pollutant removal effect. Among them, both ultraviolet and ultrasonic use their generated active free radicals (mainly hydroxyl radicals) for direct or indirect oxidation to strengthen the Fenton process. And active free radicals (especially hydroxyl radicals) are highly reactive chemical substances, and their survival time in the liquid phase is extremely short, usually on the scale of nanoseconds to milliseconds. Therefore, the present utility model simultaneously arranges medium pressure ultraviolet and ultrasonic stirring in the catalytic oxidation tank of the Fenton reaction. The reaction occurs instantaneously at the same time, making the best use of the photolysis activity of ultraviolet light, the strong oxidizing property of ·OH and the enhancement of ultrasonic on the ultraviolet-Fenton reaction, so that the Fenton oxidation reaction efficiency is faster, the utilization efficiency of the oxidant and the catalyst is higher, and it has more advantages.

[0021] 5. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, wherein an on-line pH meter, an alkali addition device and a mechanical turbine flocculation device are arranged in the neutralization tank. The on-line pH meter and the alkali addition device are provided to adjust the neutralization pH value, and the mechanical turbine flocculation device is provided to create gradually decreasing hydraulic conditions to ensure the stable formation of flocs, so as to improve the flocculation effect and reduce the effluent SS (suspended solids).

[0022] 6. An advanced oxidation pretreatment system for HPPO wastewater provided by the present utility model, wherein the solid-liquid separation tank adopts inclined plate precipitation. According to the "shallow layer precipitation theory", the precipitation effect can be effectively improved, the residence time can be reduced, and the floor area can be saved. Description of the Drawings

[0023] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic diagram of an advanced oxidation pretreatment system for HPPO wastewater in Embodiment 1 of the present utility model.

[0025] Description of the reference numerals: 1 - HP wastewater pretreatment unit, 2 - PO wastewater pretreatment unit, 3 - advanced oxidation unit, 4 - air flotation tank, 5 - first acid adjustment tank, 6 - second acid adjustment tank, 7 - catalyst dosing tank, 8 - catalytic oxidation tank, 9 - neutralization tank, 10 - solid-liquid separation tank, W1 - HP wastewater, W2 - PO wastewater. Specific Embodiments

[0026] The following will clearly and completely describe the technical solutions of the present utility model with reference to the drawings. Obviously, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0027] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0028] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0030] The present utility model discloses an advanced oxidation pretreatment system for HPPO wastewater, as Figure 1 shown. The pretreatment system includes an HP wastewater pretreatment unit 1 composed of a flotation tank 4 and a first acid adjustment tank 5 connected in sequence, a PO wastewater treatment unit 2 composed of a second acid adjustment tank 6 and a catalyst dosing tank 7 connected in sequence, and a catalytic oxidation tank 8 connected to the wastewater outlets of both the HP wastewater pretreatment unit 1 and the PO wastewater pretreatment unit 2, and an advanced oxidation unit 3 composed of a neutralization tank 9 and a solid-liquid separation tank 10 connected in sequence to the water outlet of the catalytic oxidation tank 8.

[0031] In a specific embodiment, an ultramicrobubble generator is provided at the bottom of the flotation tank, and a full-automatic oil skimmer is provided at the top. The ultramicrobubble generator generates ultramicrobubbles with a diameter of 100 - 200 nm, which adsorb on oil droplets or suspended substances, and the oil and suspended substances are aggregated and floated to the water surface by the buoyancy of the gas itself, and then removed by the full-automatic oil skimmer.

[0032] In a specific embodiment, the first acid adjustment tank 5 is directly connected to the flotation tank 4. The first acid adjustment tank 5 is provided with an on-line pH meter, an acid addition device, and a stirring device, which can realize on-line real-time detection and intelligent dosing under stirring conditions according to the pH value of the influent water, and adjust the pH to 2.9 - 4.0.

[0033] In a specific embodiment, an online pH meter, an acid adding device, and a stirring device are provided in the second acid adjusting tank, which can realize online real-time detection and intelligent dosing under stirring conditions according to the pH value of the influent water, and adjust the pH to 2.9 - 4.0.

[0034] In a specific embodiment, the stirring device and the catalyst dosing device provided in the catalyst dosing tank can realize intelligent dosing of the catalyst Fe according to the influent water volume value under stirring conditions. 2+ The catalyst Fe 2+ is sourced from a 1 moL / L ferrous sulfate solution, and the dosing amount of Fe 2+ is 400 - 600 mg / L.

[0035] In a specific embodiment, flow regulating valves are provided at the wastewater outlets of the HP wastewater pretreatment unit 1 and the PO wastewater pretreatment unit 2 to adjust the mixing ratio of the HP wastewater and the PO wastewater. According to the incoming water situation, the ratio of HP wastewater : PO wastewater is set to (1 - 2) : 1.

[0036] In a specific embodiment, an oxidant dosing device and a channel - type medium - pressure ultraviolet reactor assembly are provided in the catalytic oxidation tank 8. The oxidant dosing device can supplement and add the oxidant hydrogen peroxide. The hydrogen peroxide is sourced from a 30% mass fraction H2O2 solution, and is supplemented and added according to the mass ratio of H2O2 : Fe 2+ of approximately 34 : 15. The combination of medium - pressure ultraviolet and Fenton catalytic oxidation forms the UV - Fenton catalytic oxidation method, which combines the advantages of both UV / H2O2 and H2O2 / Fe 2+ technologies, and has both the photolysis activity of ultraviolet light and the strong oxidizing property of ·OH. In addition, compared with traditional technologies, the ultraviolet lamp modules of the channel - type medium - pressure ultraviolet reactor are distributed in different water layers from the bottom to the surface of the pool, effectively ensuring the ultraviolet penetration rate and the advanced oxidation effect. Among them, the channel - type medium - pressure ultraviolet reactor assembly mainly includes an anti - corrosion frame module, an ultraviolet lamp module, a ballast module, and a controller module. The specific connection structure of the channel - type medium - pressure ultraviolet reactor assembly is prior art and will not be elaborated here.

[0037] In a specific embodiment, an ultrasonic stirring device is also provided in the catalytic oxidation tank 8. By combining acoustic stirring with mechanical stirring, cavitation and shear forces are generated due to the conduction of sound waves in the water medium. While fully mixing the water body to strengthen the Fenton reaction, it further strengthens the UV - Fenten catalytic oxidation to form the ultrasonic - UV - Fenten technology, accelerating the conversion of Fe 2+ and the formation of ·OH, thereby reducing the generation of chemical sludge in the reaction tank and the dosing of Fe 2+ and hydrogen peroxide agents, and improving the pollutant removal effect. Among them, the ultrasonic stirring device mainly includes an ultrasonic generator, a stirring rod, a control panel, and a safety protection device.

[0038] In a specific embodiment, an on-line pH meter and an alkali adding device are arranged in the neutralization tank 9 to adjust the pH to about 9.0. A mechanical turbine flocculation device is arranged to create gradually decreasing hydraulic conditions to ensure the stable formation of flocs.

[0039] In a specific embodiment, the solid-liquid separation tank 10 is arranged as an inclined plate sedimentation tank, which reduces the floor area while improving the sedimentation efficiency based on the principle of shallow sedimentation.

[0040] Example 1

[0041] For the HP wastewater generated by a process line for producing propylene oxide by the HPPO method, it is an organic wastewater containing residual hydrogen peroxide mainly composed of aromatic hydrocarbons, with a COD concentration of 1500 - 2000 mg / L, a residual H2O2 concentration of 1800 - 2000 mg / L, and a pH of about 6.0. The PO wastewater is a high-concentration organic wastewater mainly composed of alcohols, with a COD concentration of 18000 - 20000 mg / L and a pH of about 9.8.

[0042] This embodiment provides an advanced oxidation pretreatment system for HPPO wastewater. For the schematic diagram, see Figure 1 , the system includes a HP wastewater pretreatment unit 1 composed of a flotation tank 4 and a first acid adjustment tank 5 connected in sequence, a PO wastewater treatment unit 2 composed of a second acid adjustment tank 6 and a catalyst dosing tank 7 connected in sequence, and an advanced oxidation unit 3 composed of a catalytic oxidation tank 8 connected to the wastewater outlets of both the HP wastewater pretreatment unit 1 and the PO wastewater pretreatment unit 2, and a neutralization tank 9 and a solid-liquid separation tank 10 connected in sequence to the water outlet of the catalytic oxidation tank 8. Specifically, an ultra-fine bubble generator is arranged at the bottom of the flotation tank, and a fully automatic oil scraper is arranged at the top. The first acid adjustment tank 5 is directly connected to the flotation tank 4, and the first acid adjustment tank 5 is provided with an on-line pH meter, an acid adding device and a stirring device. The second acid adjustment tank is provided with an on-line pH meter, an acid adding device and a stirring device, and the catalyst dosing tank 7 is provided with a stirring device and a catalyst dosing device. Flow regulating valves are arranged at the wastewater outlets of both the HP wastewater pretreatment unit 1 and the PO wastewater pretreatment unit 2. An oxidant dosing device, a channel type medium-pressure ultraviolet reactor assembly and an ultrasonic stirring device are arranged in the catalytic oxidation tank 8, an on-line pH meter, an alkali adding device and a mechanical turbine flocculation device are arranged in the neutralization tank 9, and the solid-liquid separation tank 10 is arranged as an inclined plate sedimentation tank.

[0043] The specific pretreatment process is as follows: HP wastewater W1 enters the air flotation tank 4. The ultramicrobubble generator at the bottom of the air flotation tank generates ultramicrobubbles with a size of 100 - 200 nm, which adsorb on oil droplets or suspended substances. The oil and suspended substances are aggregated and floated to the water surface by the buoyancy of the gas itself, and then removed by the fully automatic oil scraper set at the top. Subsequently, it enters the first acid adjustment tank 5, where the pH is adjusted to 4.0 under stirring conditions, and finally flows out through the wastewater outlet of the HP wastewater pretreatment unit 1; PO wastewater W2 enters the second acid adjustment tank 6, where the pH is adjusted to 4.0 under stirring conditions, and then enters the catalyst dosing tank 7 to add a 1 mol / L ferrous sulfate solution, and the dosing amount of Fe 2+ is 400 mg / L, and finally flows out through the wastewater outlet of the PO wastewater pretreatment unit 2; the HP wastewater after oil removal and acid adjustment pretreatment and the PO wastewater after acid adjustment and dosing are mixed into the catalytic oxidation tank for treatment at a ratio of 1:1. Under this condition, no additional hydrogen peroxide oxidant is required. The residual hydrogen peroxide in the HP wastewater and the catalyst Fe in the PO wastewater 2+ rapidly undergo the Fenton reaction under ultrasonic stirring to generate ·OH, and the chain reaction between ·OH and pollutants degrades organic substances. At the same time, under the irradiation of ultraviolet light emitted by the channel-type medium-pressure ultraviolet reactor, the oxidant photodecomposes to generate ·OH. Under the ultrasonic action of ultrasonic stirring, ultrasonic cavitation occurs in the water body, causing the cavitation bubbles in the water body to rapidly expand and burst in a short time, generating local high temperature and high pressure, and further evaporating water vapor to decompose and generate ·OH. Finally, it flows through the neutralization tank 9 in sequence to adjust the neutralization pH to 9.0, and then undergoes inclined plate sedimentation treatment in the solid-liquid separation tank 10 and is discharged. Thus, the utilization rate of hydrogen peroxide, the production rate of ·OH, and the pollutant degradation effect are greatly improved during the catalytic oxidation process, reducing the amount of catalyst used, that is, reducing the generation of chemical sludge, and also avoiding the generation of more secondary pollution.

[0044] After detection, the COD concentration in the effluent after treatment with the HPPO wastewater advanced oxidation pretreatment system provided in this embodiment is about 7500 mg / L, and the COD removal rate is about 27%.

[0045] Comparative Example 1

[0046] This comparative example provides an HPPO wastewater advanced oxidation pretreatment system. The difference from Example 1 is that acid adjustment treatment is not carried out in the HP wastewater pretreatment unit and the PO wastewater pretreatment unit, and a mixed acid adjustment tank is set in front of the catalytic oxidation tank, and the wastewater pH is adjusted to 4.0 in the mixed acid adjustment tank. Other conditions are the same as those in Example 1. After detection, the COD concentration in the effluent after treatment with the HPPO wastewater advanced oxidation pretreatment system provided in this comparative example is about 8800 mg / L, and the COD removal rate is about 15%.

[0047] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the creation of the present utility model.

Claims

1. An advanced oxidation pretreatment system for HPPO wastewater, characterized in that, The system includes an HP wastewater pretreatment unit (1), a PO wastewater pretreatment unit (2), and an advanced oxidation unit (3); wherein, the HP wastewater pretreatment unit (1) includes a flotation tank (4) and a first acid adjustment tank (5) connected in sequence; the PO wastewater pretreatment unit (2) includes a second acid adjustment tank (6) and a catalyst dosing tank (7) connected in sequence; the advanced oxidation unit (3) includes a catalytic oxidation tank (8) simultaneously connected to the wastewater outlets of the HP wastewater pretreatment unit (1) and the PO wastewater pretreatment unit (2), and a neutralization tank (9) and a solid-liquid separation tank (10) connected in sequence to the water outlet of the catalytic oxidation tank (8).

2. The advanced oxidation pretreatment system for HPPO wastewater according to claim 1, characterized in that, An oil skimmer is provided at the top of the flotation tank (4).

3. The advanced oxidation pretreatment system for HPPO wastewater according to claim 1, characterized in that, An ultra-fine bubble generator is provided at the bottom of the flotation tank (4).

4. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, Online pH meters and acid addition devices are provided in both the first acid adjustment tank (5) and the second acid adjustment tank (6).

5. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, A catalyst dosing device is provided in the catalyst dosing tank (7).

6. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, Stirring devices are also provided in the first acid adjustment tank (5), the second acid adjustment tank (6), and the catalyst dosing tank (7).

7. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, Flow regulating valves are provided at the wastewater outlets of the HP wastewater pretreatment unit (1) and the PO wastewater pretreatment unit (2).

8. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, An oxidant dosing device, an ultrasonic stirring device, and a channel type medium-pressure ultraviolet reactor assembly are provided in the catalytic oxidation tank (8).

9. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1 to 3, characterized in that, An online pH meter, an alkali addition device, and a mechanical turbine flocculation device are provided in the neutralization tank (9).

10. The advanced oxidation pretreatment system for HPPO wastewater according to any one of claims 1-3, characterized in that, The solid-liquid separation tank (10) is an inclined plate sedimentation tank.

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