A cascaded dual-effect advanced oxidation wastewater treatment process

Abstract

This invention discloses a cascaded dual-effect advanced oxidation wastewater treatment process, belonging to the field of wastewater treatment technology. The cascaded dual-effect advanced oxidation wastewater treatment process mainly includes: wastewater, after adjustment and pretreatment, is mixed with a catalyst and subjected to two stages of advanced oxidation (both with ultrasound) using Fenton and US-O3 (ultrasound-ozone oxidation); oxidation liquid separation: the clarified liquid is discharged or reused after biochemical treatment; solid materials and recyclable catalyst are regenerated and recycled. The regenerated wastewater is recycled, and the biochemical sludge is transported off-site. This method can effectively remove organic fluoride and various recalcitrant pollutants from wastewater discharged from industries such as fluorochemicals, semiconductors, and pharmaceuticals.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a cascaded dual-effect advanced oxidation wastewater treatment process. Background Technology

[0002] With the rapid development of industries such as pharmaceuticals, chemicals, and fine chemicals, the discharge of recalcitrant organic wastewater generated during production processes has been increasing year by year. This type of wastewater is characterized by high COD concentration, poor biodegradability, complex composition, and high toxicity. It contains recalcitrant components such as aromatic compounds, halogenated hydrocarbons, and organic fluorides. Conventional physical, chemical, and biochemical treatment processes are difficult to meet emission standards, making it a key and challenging area in environmental governance.

[0003] Advanced oxidation technologies, which can generate hydroxyl radicals with strong oxidizing power, can non-selectively degrade recalcitrant organic matter in wastewater, making them the core technology for treating such wastewater. Among them, Fenton advanced oxidation and ozone catalytic oxidation are the two most widely used technologies in industry.

[0004] Fenton advanced oxidation technology with Fe 2+ / Fe 3+ Using transition metal oxides as catalysts to catalyze the production of ·OH from H2O2 has advantages such as high oxidation efficiency and fast reaction rate. However, the traditional Fenton process requires the addition of a large amount of H2O2, which not only increases the cost of reagents but may also cause secondary pollution due to excessive H2O2. At the same time, conventional Fenton catalysts are mostly homogeneous Fe-based materials, which easily generate a large amount of iron sludge, resulting in high costs for subsequent sludge treatment. Furthermore, the catalysts cannot be recycled, further increasing operating costs. In addition, traditional Fenton-like reactions are strictly limited by pH, have a narrow range of applications, and are difficult to adapt to recalcitrant wastewater with different water qualities.

[0005] Ozone catalytic oxidation technology utilizes ozone to decompose under the action of a catalyst to generate active free radicals such as ·OH and singlet oxygen, thereby degrading organic matter. It has advantages such as no sludge production and wide pH adaptability. However, this technology has problems such as low ozone utilization rate, direct emission of O2 generated by ozone decomposition leading to resource waste, easy deactivation of catalyst due to surface adsorption of pollutants, and low mass transfer efficiency resulting in limited oxidation effect. When used alone, it is difficult to achieve deep treatment of recalcitrant wastewater, and the operating cost is high.

[0006] To address the shortcomings of single advanced oxidation technologies, cascade processes combining Fenton oxidation and ozone catalytic oxidation have emerged in existing technologies. However, these processes still suffer from several deficiencies: First, they fail to achieve material recycling; the Fenton reaction still requires the addition of H2O2, and the O2 generated from ozone decomposition is directly emitted, resulting in significant resource waste. Second, the catalysts are mostly single-component with limited catalytic activity and lack effective online cleaning and regeneration mechanisms, leading to catalyst deactivation and loss, resulting in high operating costs. Third, they lack effective mass transfer enhancement methods, resulting in insufficient gas-liquid contact area and limiting oxidation reaction efficiency. Fourth, the catalyst recycling system is imperfect, making continuous and stable recycling difficult, and the triggering conditions and specific processes for catalyst regeneration are not clearly defined, resulting in poor practicality. Therefore, developing an advanced oxidation process that can achieve material recycling, reduce reagent costs, extend catalyst life, improve oxidation efficiency, and is suitable for the pretreatment of high-concentration, recalcitrant wastewater has become a hot topic in the current environmental protection technology field. Summary of the Invention

[0007] The purpose of this invention is to provide a cascaded dual-effect advanced oxidation wastewater treatment process to solve the technical problem that the existing technology is not effective in treating organic fluoride and various recalcitrant pollutants in wastewater discharged from industries such as fluorochemicals, semiconductors, and pharmaceuticals.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a cascaded dual-effect advanced oxidation wastewater treatment process, comprising the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation. Under the action of an ultrasonic generator, primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation. Under the action of the ultrasonic generator, secondary oxidation water is obtained and then sent to the separation unit. The separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit to restore catalytic activity under the action of regeneration agents; the regenerated catalyst enters the catalyst mixing tank, is mixed with the fresh catalyst replenished in the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

[0009] Preferably, in step one, the pH is adjusted to 2-11; in step two, the primary advanced oxidation time is 1-2 hours, the ultrasonic generator frequency is 28-40 Hz, and it operates intermittently for 5-10 minutes / hour; in step three, the secondary advanced oxidation time is 1-2 hours, and an inclined tube sedimentation tank (surface loading of 1-2 m³) is used in the separation unit. 3 / (m 2 ·h)) to perform precipitation separation.

[0010] Preferably, in step three, a composite adsorbent is added to the deep treatment unit at a dosage of 4-8 g / L. The preparation method of the composite adsorbent includes the following steps: Q1: Add pyridine-2,6-dicarboxaldehyde, diaminomaleonitrile and p-toluenesulfonic acid to a container containing ethanol, heat in an oil bath under reflux and react. After the reaction is complete, wash, centrifuge, and vacuum dry to obtain a powder. Q2: Add hydroxylamine hydrochloride and sodium hydroxide to a container containing a mixed solution of methanol and distilled water, stir and mix, then add the powdered substance, heat and stir to react, after the reaction is complete, wash, centrifuge, and vacuum dry to obtain the composite adsorbent.

[0011] In the above process, the synthesis reaction formula of the composite adsorbent is as follows:

[0012] Preferably, in Q1, the ratio of pyridine-2,6-dicarboxaldehyde, diaminomaleitrile, p-toluenesulfonic acid, and ethanol is (2.42-2.88) g : (2.32-2.46) g : (0.03-0.05) g : (480-520) mL. The reaction is carried out under reflux in an oil bath at 80-90°C for 48-52 h. The mixture is washed with ethanol, centrifuged at 10000-12000 rpm for 10-20 min, and then vacuum dried at 70-80°C for 20-24 h.

[0013] Preferably, in Q2, the ratio of hydroxylamine hydrochloride, sodium hydroxide, methanol, distilled water, and powdered substances is (2.12-2.38) g : (1.04-1.18) g : (4-6) mL : (1-1.3) mL : (0.42-0.55) g. The heating and stirring reaction temperature is 60-70℃ for 10-12 h. The mixture is washed with distilled water, centrifuged at 10000-12000 rpm for 10-20 min, and vacuum dried at 70-80℃ for 20-24 h.

[0014] Preferably, in step two, the method for preparing the catalyst includes the following steps: S1: Polyethylene glycol monomethyl ether, hydroquinone and p-toluenesulfonic acid are added to a container, heated and stirred to react, nitrogen gas is introduced, then the temperature is raised and stirred, acrylic acid is added to the container, heated to react, then cooled, dissolved, washed, extracted, washed again, and rotary evaporated to obtain the monomer; S2: Add monomer, acrylic acid and isopropanol to a container in sequence, stir and mix, add maleic anhydride aqueous solution, stir, heat, add potassium persulfate aqueous solution, stir to react, cool, adjust pH to obtain a mixture; S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them to obtain shell particles; add manganese nitrate to deionized water, stir and mix to obtain a manganese precursor solution, add the mixture to the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, disperse by ultrasonication, impregnate by vacuum, allow to stand for aging, remove the shell particles, dry and calcine, cool, wash, dry, and sieve to obtain the catalyst.

[0015] In the above process, firstly, p-toluenesulfonic acid catalyzes the esterification reaction of polyethylene glycol monomethyl ether and acrylic acid to obtain monomers; then, potassium persulfate thermally decomposes to generate free radicals, initiating copolymerization of the monomers, acrylic acid, and maleic anhydride to form a carboxyl-containing polymer; subsequently, scallop shells are calcined to form a porous support, and manganese nitrate provides Mn. 2+ The mixture is combined with the solution to form a manganese precursor composite solution; finally, the carrier is impregnated with Mn. 2+ After polymerization, vacuum promotes infiltration; during calcination, polymer decomposes to create pores, Mn 2+ Converted to MnO x The active components are firmly loaded onto the carrier surface.

[0016] Preferably, in step S1, the ratio of polyethylene glycol monomethyl ether, hydroquinone, p-toluenesulfonic acid, and acrylic acid is (0.12-0.18) g : (0.0036-0.0042) g : (0.0017-0.0022) g : (0.22-0.26) g, the relative molecular mass of polyethylene glycol monomethyl ether is 350, the heating and stirring reaction temperature is 45-55℃, the time is 30-45 min, the temperature is raised to 80-85℃ and stirred, the temperature is raised to 90-92℃ and reacted for 3-4 h, the temperature is lowered to 28-30℃, dissolved in cyclohexane, washed with 10wt% sodium hydroxide aqueous solution, and then washed again with saturated sodium chloride aqueous solution.

[0017] Preferably, in step S2, the ratio of monomer, acrylic acid, isopropanol, maleic anhydride aqueous solution, and potassium persulfate aqueous solution is (0.22-0.27) g : (0.38-0.46) g : (0.0072-0.0092) g : (0.15-0.19) mL : (0.0056-0.0064) mL, the concentration of maleic anhydride aqueous solution is 0.25 g / mL, the concentration of potassium persulfate aqueous solution is 0.06 g / mL, the temperature is raised to 75-80℃, the reaction is stirred for 4-6 h, and the pH is adjusted to 8-9 with 30 wt% sodium hydroxide aqueous solution.

[0018] Preferably, in step S3, the calcination temperature is 300-500℃, the time is 1-3h, the ratio of manganese nitrate to deionized water is (2.2-3.5)g:(20-25)mL, and the volume ratio of the mixed solution to the manganese precursor solution is (5-8):(20-25); in step S4, ultrasonic dispersion is performed for 10-30min, vacuum impregnation for 20-40min, and static aging for 4-8h. Under air atmosphere, the calcination temperature is 250-450℃, and the time is 2-5h.

[0019] Preferably, in step four, the regenerating agent is 0.5-1 mol / L hydrochloric acid.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In the process of wastewater treatment, this invention synergistically couples Fenton-like oxidation and ozone catalytic oxidation, utilizing primary chain-severed macromolecular organic matter and secondary deep mineralization of small molecules to achieve complementary types of free radicals, thereby improving oxidation efficiency, COD removal rate and reducing color; and the use of inclined tube precipitation can improve catalyst retention rate; in addition, the catalyst has a wide pH tolerance range, can treat recalcitrant wastewater, and is suitable for wastewater treatment in the organic fluorine industry.

[0021] 2. The composite adsorbent obtained in this invention is applied to a cascaded dual-effect advanced oxidation wastewater treatment process. It can utilize chelation, electrostatic action, and surface enrichment to efficiently remove heavy metals, suspended impurities, color components, and some recalcitrant organic matter from wastewater, thereby significantly improving the wastewater treatment effect.

[0022] 3. This invention applies the prepared catalyst to Fenton-like oxidation units and US-O3 units, significantly improving wastewater treatment efficiency. The calcined seashell carrier serves as both a porous carrier and an in-situ alkali source (CaO slowly releases OH). -This process utilizes a triple effect of promoting ozone decomposition and adsorption enrichment, significantly enhancing the utilization efficiency of ·OH. With this catalyst, the reaction liquid from the Fenton-like oxidation unit does not require separation; it flows directly into the US-O3 unit, where the catalyst continues to function. Subsequently, it undergoes a catalyst recovery and regeneration unit for closed-loop reuse. Combined with a cascade replenishment of fresh catalyst, this significantly extends the catalyst's lifespan and reduces solid waste and operating costs. Furthermore, this process is adaptable to a wide water quality range of pH 2-11, is highly efficient for various recalcitrant organic pollutants, and simultaneously achieves closed-loop management of waste seashells and recycled wastewater, embodying the concept of green recycling.

[0023] 4. The Fenton-like oxidation unit in this invention utilizes O2 and H2 under the action of a catalyst. + H2O2 is generated in situ. In the US-O3 unit, O3 is catalytically converted into ·OH and O2. The collected O2 is recycled to the Fenton-like oxidation unit as an oxygen source for H2O2. At the same time, the effluent from the Fenton-like oxidation unit carries H2O2 to the US-O3 unit as an initiator for ozone catalytic oxidation. Compared with the conventional Fenton system, this invention can reduce the amount of H2O2 added, and the O2 generated by the ozone reaction is fully reused as an oxygen source, thereby reducing the overall energy consumption of the system. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the cascaded dual-effect advanced oxidation wastewater treatment process in this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: This example discloses a method for preparing a composite adsorbent, including the following steps: Q1: Add 2.65g pyridine-2,6-dicarboxaldehyde, 2.39g diaminomaleonitrile and 0.04g p-toluenesulfonic acid to a container containing 500mL ethanol, heat in an oil bath at 85℃ under reflux for 48h, wash with ethanol after the reaction, centrifuge at 12000rpm for 10min, and dry under vacuum at 70℃ for 24h to obtain a powder. Q2: Add 2.25g of hydroxylamine hydrochloride and 1.11g of sodium hydroxide to a container containing a mixture of 5mL of methanol and 1.15mL of distilled water. After stirring and mixing, add 0.48g of powder. Heat and stir at 70℃ for 12h. After the reaction is complete, wash with distilled water, centrifuge at 12000rpm for 10min, and vacuum dry at 75℃ for 24h to obtain the composite adsorbent.

[0028] This embodiment discloses a method for preparing a catalyst, including the following steps: S1: 0.15 g of polyethylene glycol monomethyl ether with a relative molecular mass of 350, 0.0039 g of hydroquinone and 0.0019 g of p-toluenesulfonic acid were added to a container, heated and stirred at 50°C for 30 min, nitrogen gas was introduced, and then the temperature was raised to 80°C and stirred. 0.24 g of acrylic acid was added to the container, heated to 90°C and reacted for 4 h, and then cooled to 28°C and dissolved in cyclohexane. The solution was washed with 10 wt% sodium hydroxide aqueous solution, extracted, washed again with saturated sodium chloride aqueous solution, and rotary evaporated to obtain the monomer. S2: 0.24 g monomer, 0.42 g acrylic acid and 0.0082 g isopropanol were added to a container in sequence and stirred. After mixing, 0.17 mL of maleic anhydride aqueous solution with a concentration of 0.25 g / mL was added and stirred. The temperature was raised to 75 °C and 0.006 mL of potassium persulfate aqueous solution with a concentration of 0.06 g / mL was added. After stirring and reacting for 4 h, the mixture was cooled and the pH was adjusted to 8 with 30 wt% sodium hydroxide aqueous solution to obtain a mixed solution. S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them at 400℃ for 2 hours to obtain shell particles; add 2.8g of manganese nitrate to 22.5mL of deionized water, stir and mix to obtain a manganese precursor solution; add 6.5mL of the mixture to 22.5mL of the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, ultrasonically disperse for 20 min, vacuum impregnate for 30 min, let stand for aging for 8 h, take out the shell particles, dry them and calcine at 350℃ for 4 h (in air atmosphere), cool, wash, dry and sieve to obtain the catalyst.

[0029] See Figure 1 As shown, this embodiment discloses a cascaded dual-effect advanced oxidation wastewater treatment process, including the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted to 2-11, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation for 2 hours. Under the action of an ultrasonic generator (frequency 30Hz, intermittent operation, running for 1 hour and stopping for 8 minutes), primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation for 2 hours. Under the action of an ultrasonic generator, secondary oxidation water is obtained, which is then sent to the separation unit. The separation unit uses an inclined tube sedimentation tank (surface loading of 1.5m). 3 / (m 2 ·h)) precipitation separation, the separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The deep treatment unit is added with a composite adsorbent at a dosage of 6g / L. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit, where its catalytic activity is restored under the action of the regeneration agent (1 mol / L hydrochloric acid). The regenerated catalyst enters the catalyst mixing tank, mixes with the fresh catalyst replenished from the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

[0030] Example 2: This example discloses a method for preparing a composite adsorbent, including the following steps: Q1: Add 2.42g of pyridine-2,6-dicarboxaldehyde, 2.32g of diaminomaleonitrile and 0.05g of p-toluenesulfonic acid to a container containing 520mL of ethanol, heat in an oil bath at 85℃ under reflux for 48h, wash with ethanol after the reaction, centrifuge at 12000rpm for 10min, and dry under vacuum at 70℃ for 24h to obtain a powder. Q2: Add 2.12g of hydroxylamine hydrochloride and 1.04g of sodium hydroxide to a container containing a mixture of 4mL of methanol and 1mL of distilled water. After stirring and mixing, add 0.42g of powder. Heat and stir at 70℃ for 12h. After the reaction is complete, wash with distilled water, centrifuge at 12000rpm for 10min, and vacuum dry at 75℃ for 24h to obtain the composite adsorbent.

[0031] This embodiment discloses a method for preparing a catalyst, including the following steps: S1: 0.12 g of polyethylene glycol monomethyl ether with a relative molecular mass of 350, 0.0036 g of hydroquinone and 0.0017 g of p-toluenesulfonic acid were added to a container, heated and stirred at 50°C for 30 min, nitrogen gas was introduced, and then the temperature was raised to 80°C and stirred. 0.22 g of acrylic acid was added to the container, heated to 90°C and reacted for 4 h, and then cooled to 28°C and dissolved in cyclohexane. The solution was washed with 10 wt% sodium hydroxide aqueous solution, extracted, washed again with saturated sodium chloride aqueous solution, and rotary evaporated to obtain the monomer. S2: 0.22g monomer, 0.38g acrylic acid and 0.0092g isopropanol were added to a container in sequence and stirred. After mixing, 0.15mL of maleic anhydride aqueous solution with a concentration of 0.25g / mL was added, stirred, heated to 75℃, and 0.0056mL of potassium persulfate aqueous solution with a concentration of 0.06g / mL was added. After stirring and reacting for 4h, the mixture was cooled and the pH was adjusted to 8 with 30wt% sodium hydroxide aqueous solution to obtain a mixed solution. S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them at 400℃ for 2 hours to obtain shell particles; add 2.2g of manganese nitrate to 20mL of deionized water, stir and mix to obtain a manganese precursor solution; add 5mL of the mixture to 25mL of the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, ultrasonically disperse for 20 min, vacuum impregnate for 30 min, let stand for aging for 8 h, take out the shell particles, dry them and calcine at 350℃ for 4 h (in air atmosphere), cool, wash, dry and sieve to obtain the catalyst.

[0032] See Figure 1 As shown, this embodiment discloses a cascaded dual-effect advanced oxidation wastewater treatment process, including the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted to 2-11, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation for 2 hours. Under the action of an ultrasonic generator (frequency 30Hz, intermittent operation, running for 1 hour and stopping for 8 minutes), primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation for 2 hours. Under the action of an ultrasonic generator, secondary oxidation water is obtained, which is then sent to the separation unit. The separation unit uses an inclined tube sedimentation tank (surface loading of 1.5m). 3 / (m 2·h)) precipitation separation, the separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The deep treatment unit is added with a composite adsorbent at a dosage of 6g / L. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit, where its catalytic activity is restored under the action of the regeneration agent (1 mol / L hydrochloric acid). The regenerated catalyst enters the catalyst mixing tank, mixes with the fresh catalyst replenished from the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

[0033] Example 3: This example discloses a method for preparing a composite adsorbent, including the following steps: Q1: Add 2.88g of pyridine-2,6-dicarboxaldehyde, 2.46g of diaminomaleonitrile and 0.03g of p-toluenesulfonic acid to a container containing 480mL of ethanol, heat in an oil bath at 85℃ under reflux for 48h, wash with ethanol after the reaction, centrifuge at 12000rpm for 10min, and dry under vacuum at 70℃ for 24h to obtain a powder. Q2: Add 2.38g of hydroxylamine hydrochloride and 1.18g of sodium hydroxide to a container containing a mixture of 6mL of methanol and 1.3mL of distilled water. After stirring and mixing, add 0.55g of powder. Heat and stir at 70℃ for 12h. After the reaction is complete, wash with distilled water, centrifuge at 12000rpm for 10min, and vacuum dry at 75℃ for 24h to obtain the composite adsorbent.

[0034] This embodiment discloses a method for preparing a catalyst, including the following steps: S1: 0.18 g of polyethylene glycol monomethyl ether with a relative molecular mass of 350, 0.0042 g of hydroquinone and 0.0022 g of p-toluenesulfonic acid were added to a container, heated and stirred at 50°C for 30 min, nitrogen gas was introduced, and then the temperature was raised to 80°C and stirred. 0.26 g of acrylic acid was added to the container, heated to 90°C and reacted for 4 h, and then cooled to 28°C and dissolved in cyclohexane. The solution was washed with 10 wt% sodium hydroxide aqueous solution, extracted, washed again with saturated sodium chloride aqueous solution, and rotary evaporated to obtain the monomer. S2: 0.27g monomer, 0.46g acrylic acid and 0.0072g isopropanol were added to a container in sequence and stirred. After mixing, 0.19mL of maleic anhydride aqueous solution with a concentration of 0.25g / mL was added, stirred, heated to 75℃, and 0.0064mL of potassium persulfate aqueous solution with a concentration of 0.06g / mL was added. After stirring and reacting for 4h, the mixture was cooled and the pH was adjusted to 8 with 30wt% sodium hydroxide aqueous solution to obtain a mixed solution. S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them at 400℃ for 2 hours to obtain shell particles; add 3.5g of manganese nitrate to 25mL of deionized water, stir and mix to obtain a manganese precursor solution, add 8mL of the mixture to 20mL of the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, ultrasonically disperse for 20 min, vacuum impregnate for 30 min, let stand for aging for 8 h, take out the shell particles, dry them and calcine at 350℃ for 4 h (in air atmosphere), cool, wash, dry and sieve to obtain the catalyst.

[0035] See Figure 1 As shown, this embodiment discloses a cascaded dual-effect advanced oxidation wastewater treatment process, including the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted to 2-11, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation for 2 hours. Under the action of an ultrasonic generator (frequency 30Hz, intermittent operation, running for 1 hour and stopping for 8 minutes), primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation for 2 hours. Under the action of an ultrasonic generator, secondary oxidation water is obtained, which is then sent to the separation unit. The separation unit uses an inclined tube sedimentation tank (surface loading of 1.5m). 3 / (m 2 ·h)) precipitation separation, the separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The deep treatment unit is added with a composite adsorbent at a dosage of 6g / L. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit, where its catalytic activity is restored under the action of the regeneration agent (1 mol / L hydrochloric acid). The regenerated catalyst enters the catalyst mixing tank, mixes with the fresh catalyst replenished from the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

[0036] Example 4: This example discloses a method for preparing a composite adsorbent, including the following steps: Q1: Add 2.71g pyridine-2,6-dicarboxaldehyde, 2.41g diaminomaleonitrile and 0.05g p-toluenesulfonic acid to a container containing 510mL ethanol, heat in an oil bath at 85℃ under reflux for 48h, wash with ethanol after the reaction, centrifuge at 12000rpm for 10min, and dry under vacuum at 70℃ for 24h to obtain a powder. Q2: Add 2.31g of hydroxylamine hydrochloride and 1.14g of sodium hydroxide to a container containing a mixture of 5.5mL of methanol and 1.2mL of distilled water. After stirring and mixing, add 0.51g of powder. Heat and stir at 70℃ for 12h. After the reaction is complete, wash with distilled water, centrifuge at 12000rpm for 10min, and vacuum dry at 75℃ for 24h to obtain the composite adsorbent.

[0037] This embodiment discloses a method for preparing a catalyst, including the following steps: S1: 0.16 g of polyethylene glycol monomethyl ether with a relative molecular mass of 350, 0.0038 g of hydroquinone and 0.0018 g of p-toluenesulfonic acid were added to a container, heated and stirred at 50°C for 30 min, nitrogen gas was introduced, and then the temperature was raised to 80°C and stirred. 0.25 g of acrylic acid was added to the container, heated to 90°C and reacted for 4 h, and then cooled to 28°C and dissolved in cyclohexane. The solution was washed with 10 wt% sodium hydroxide aqueous solution, extracted, washed again with saturated sodium chloride aqueous solution, and rotary evaporated to obtain the monomer. S2: 0.26g monomer, 0.44g acrylic acid and 0.0087g isopropanol were added to a container in sequence and stirred. After mixing, 0.18mL of maleic anhydride aqueous solution with a concentration of 0.25g / mL was added, stirred, heated to 75℃, and 0.0062mL of potassium persulfate aqueous solution with a concentration of 0.06g / mL was added. After stirring and reacting for 4h, the mixture was cooled and the pH was adjusted to 8 with 30wt% sodium hydroxide aqueous solution to obtain a mixed solution. S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them at 400℃ for 2 hours to obtain shell particles; add 3.1g of manganese nitrate to 24mL of deionized water, stir and mix to obtain a manganese precursor solution; add 7mL of the mixture to 24mL of the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, ultrasonically disperse for 20 min, vacuum impregnate for 30 min, let stand for aging for 8 h, take out the shell particles, dry them and calcine at 350℃ for 4 h (in air atmosphere), cool, wash, dry and sieve to obtain the catalyst.

[0038] See Figure 1 As shown, this embodiment discloses a cascaded dual-effect advanced oxidation wastewater treatment process, including the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted to 2-11, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation for 2 hours. Under the action of an ultrasonic generator (frequency 30Hz, intermittent operation, running for 1 hour and stopping for 8 minutes), primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation for 2 hours. Under the action of an ultrasonic generator, secondary oxidation water is obtained, which is then sent to the separation unit. The separation unit uses an inclined tube sedimentation tank (surface loading of 1.5m). 3 / (m 2 ·h)) precipitation separation, the separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The deep treatment unit is added with a composite adsorbent at a dosage of 6g / L. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit, where its catalytic activity is restored under the action of the regeneration agent (1 mol / L hydrochloric acid). The regenerated catalyst enters the catalyst mixing tank, mixes with the fresh catalyst replenished from the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

[0039] Comparative Example 1: Compared with Example 1, Comparative Example 1 uses activated carbon instead of composite adsorbent in the cascaded dual-effect advanced oxidation wastewater treatment process, while keeping other conditions unchanged.

[0040] Comparative Example 2: Compared with Example 1, Comparative Example 2 does not add a catalyst in the cascaded double-effect advanced oxidation wastewater treatment process, and all other conditions remain unchanged.

[0041] Performance testing: Wastewater (self-made) was treated according to the methods of Examples 1-4 and Comparative Examples 1-2. The pollutant content in the wastewater after the experiment was measured. The untreated wastewater contained: COD = 5680 mg / L, Hg = 1.00 mg / L, Cd = 1.00 mg / L, Cr = 5.00 mg / L, Pb = 1.00 mg / L, color = 700 degrees, ammonia nitrogen = 25.00 mg / L, suspended solids (SS) = 650 mg / L, total phosphorus (TP) = 12 mg / L, and sulfur dioxide (F). - =12.00 mg / L, pH=8, COD was tested using the dichromate method, Hg using cold atomic absorption spectrophotometry, Cd using the dithizone spectrophotometry, Cr using the diphenylcarbazide spectrophotometry, Pb using the dithizone spectrophotometry, colorimetry using the dilution factor method, ammonia nitrogen using Nessler's reagent spectrophotometry, SS using the gravimetric method, TP using the ammonium molybdate spectrophotometry, F - The electrode method was used for testing, and the test results are shown in Table 1:

[0042] As shown in Table 1, the test results demonstrate that the methods described in Examples 1-4 can effectively remove pollutants from wastewater. A comparison between Comparative Example 1 and Examples 1-4 reveals that the use of a composite adsorbent can effectively improve the pollutant removal efficiency; a comparison between Comparative Example 2 and Examples 1-4 shows that the use of a catalyst can effectively improve the pollutant removal efficiency.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A cascaded dual-effect advanced oxidation wastewater treatment process, characterized in that, Includes the following steps: Step 1: The wastewater first enters the wastewater equalization tank, where the pH is adjusted, and then it is transported to the pretreatment unit to remove suspended solids and impurities. The pretreated wastewater is then temporarily stored in the intermediate water tank. Step 2: After mixing the wastewater and catalyst in the intermediate water tank in a mixer, the mixture is sent to a Fenton-like oxidation unit for primary advanced oxidation. Under the action of an ultrasonic generator, primary oxidized water is obtained. Step 3: The primary oxidation water is transported to the US-O3 unit for secondary advanced oxidation. Under the action of the ultrasonic generator, secondary oxidation water is obtained and then sent to the separation unit. The separated clear liquid is treated by the biochemical unit and then enters the deep treatment unit. The separated recyclable catalyst and solid materials enter the collection tank. Step 4: The effluent from the deep treatment unit is collected in the effluent tank for discharge or reuse; the recyclable material in the collection tank is sent to the regeneration unit to restore catalytic activity under the action of regeneration agents; the regenerated catalyst enters the catalyst mixing tank, is mixed with the fresh catalyst replenished in the catalyst silo, and then returns to the mixer for recycling via the intermediate storage tank; the waste liquid generated during the regeneration process enters the waste liquid storage tank and is returned to the wastewater equalization tank for unified treatment; the excess sludge generated by the biochemical unit enters the sludge treatment unit, is reduced in volume, and then outsourced for treatment.

2. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 1, characterized in that, In step one, the pH is adjusted to 2-11. In step two, the primary advanced oxidation time is 1-2 hours, the ultrasonic generator frequency is 28-40 Hz, and it operates intermittently for 5-10 minutes / hour. In step three, the secondary advanced oxidation time is 1-2 hours, and an inclined tube sedimentation tank (surface loading of 1-2 m³) is used in the separation unit. 3 / (m 2 ·h)) to perform precipitation separation.

3. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 1, characterized in that, In step three, a composite adsorbent is added to the deep treatment unit at a dosage of 4-8 g / L. The method for preparing the composite adsorbent is described below. Includes the following steps: Q1: Add pyridine-2,6-dicarboxaldehyde, diaminomaleonitrile and p-toluenesulfonic acid to a container containing ethanol, heat in an oil bath under reflux and react. After the reaction is complete, wash, centrifuge, and vacuum dry to obtain a powder. Q2: Add hydroxylamine hydrochloride and sodium hydroxide to a container containing a mixed solution of methanol and distilled water, stir and mix, then add the powdered substance, heat and stir to react, after the reaction is complete, wash, centrifuge, and vacuum dry to obtain the composite adsorbent.

4. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 3, characterized in that, In Q1, the ratio of pyridine-2,6-dicarboxaldehyde, diaminomaleitrile, p-toluenesulfonic acid, and ethanol is (2.42-2.88) g : (2.32-2.46) g : (0.03-0.05) g : (480-520) mL.

5. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 3, characterized in that, In Q2, the ratio of hydroxylamine hydrochloride, sodium hydroxide, methanol, distilled water and powdered substances is (2.12-2.38) g : (1.04-1.18) g : (4-6) mL : (1-1.3) mL : (0.42-0.55) g.

6. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 1, characterized in that, In step two, the method for preparing the catalyst includes the following steps: S1: Polyethylene glycol monomethyl ether, hydroquinone and p-toluenesulfonic acid are added to a container, heated and stirred to react, nitrogen gas is introduced, then the temperature is raised and stirred, acrylic acid is added to the container, heated to react, then cooled, dissolved, washed, extracted, washed again, and rotary evaporated to obtain the monomer; S2: Add monomer, acrylic acid and isopropanol to a container in sequence, stir and mix, add maleic anhydride aqueous solution, stir, heat, add potassium persulfate aqueous solution, stir to react, cool, adjust pH to obtain a mixture; S3: Wash the scallop shells with distilled water, dry them, crush them, sieve them, and calcine them to obtain shell particles; add manganese nitrate to deionized water, stir and mix to obtain a manganese precursor solution, add the mixture to the manganese precursor solution, stir and mix to obtain a manganese precursor composite solution. S4: Add the shell particles to the manganese precursor composite liquid, disperse by ultrasonication, impregnate by vacuum, allow to stand for aging, remove the shell particles, dry and calcine, cool, wash, dry, and sieve to obtain the catalyst.

7. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 6, characterized in that, In S1, the ratio of polyethylene glycol monomethyl ether, hydroquinone, p-toluenesulfonic acid and acrylic acid is (0.12-0.18) g : (0.0036-0.0042) g : (0.0017-0.0022) g : (0.22-0.26) g.

8. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 6, characterized in that, In S2, the ratio of monomer, acrylic acid, isopropanol, maleic anhydride aqueous solution and potassium persulfate aqueous solution is (0.22-0.27) g : (0.38-0.46) g : (0.0072-0.0092) g : (0.15-0.19) mL : (0.0056-0.0064) mL.

9. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 6, characterized in that, In S3, the ratio of manganese nitrate to deionized water is (2.2-3.5) g: (20-25) mL, and the volume ratio of the mixed solution to the manganese precursor solution is (5-8): (20-25).

10. The cascaded dual-effect advanced oxidation wastewater treatment process according to claim 1, characterized in that, In step four, the regenerative agent is 0.5-1 mol / L hydrochloric acid.

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