A method for treating wastewater by ultrasonic wave combined with ozone catalytic oxidation and dynamic flocculation

Abstract

The application discloses a wastewater treatment method of ultrasonic wave cooperation ozone catalytic oxidation and dynamic flocculation, which comprises the following steps: simultaneously adding ozone (O3), nanoscale manganese dioxide and polyaluminum chloride (PAC) into wastewater, and applying high-energy ultrasonic cavitation effect; simultaneously adjusting pH value to 7, so that ozone oxidation and flocculation reaction are synchronously performed; maintaining high-energy ultrasonic cavitation effect, and continuously adding cationic polyacrylamide (CPAM) to strengthen flocculation formation and form 'core-shell' structure with a pore diameter of 2-50 nm; reducing ultrasonic power density to continuously act on organic matter and keep flocculation looseness; stopping high-energy ultrasonic cavitation effect, standing and depositing, and separating sludge and clean water. The application dynamically couples ultrasonic cavitation effect, manganese dioxide catalytic oxidation, ozone advanced oxidation and inorganic-organic composite flocculation, forms a synergistic effect chain of 'cavitation degradation-catalytic oxidation bond breaking-flocculation capture', and makes COD removal rate reach 90-95%.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a wastewater treatment method that simultaneously performs ultrasonic and catalyst-enhanced ozone oxidation and flocculation, and is particularly suitable for the treatment of high-concentration, recalcitrant organic wastewater (such as dyeing, pharmaceutical, and petrochemical wastewater). Background Technology

[0002] The current field of industrial wastewater treatment faces technical bottlenecks such as low removal efficiency and high operating costs for recalcitrant organic matter. While traditional ozone oxidation technology can degrade some organic matter, it suffers from low ozone mass transfer efficiency (the mass transfer coefficient from the gas phase to the liquid phase is typically less than 0.1 min⁻¹) and limited hydroxyl radical yield (<30%), resulting in low oxidation efficiency for benzene compounds and heterocyclic compounds. In conventional flocculation processes, polyaluminum chloride (PAC) generally achieves a removal rate of less than 40% for dissolved small-molecule organic matter, while cationic polyacrylamide (CPAM), when used alone, easily forms dense flocs, hindering further degradation of internal pollutants. Existing ultrasound-assisted technologies often employ a series "oxidation followed by flocculation" approach, which not only increases the reactor volume by more than 30% but also leads to the escape of intermediate products due to the separation of the oxidation and flocculation processes. A more prominent problem is that traditional processes fail to effectively utilize the microjets (with velocities up to 100 m / s) generated by ultrasonic cavitation to optimize the floc structure, as well as the local high-temperature and high-pressure environment during cavitation bubble collapse to promote ozone conversion, resulting in a double waste of energy and reagents. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0004] The purpose of this invention is to provide a wastewater treatment method that combines ultrasonic cavitation with ozone catalytic oxidation and dynamic flocculation. By dynamically coupling ultrasonic cavitation, manganese dioxide catalytic oxidation, advanced ozone oxidation, and inorganic-organic composite flocculation, a synergistic chain of "cavitation degradation - catalytic oxidation bond breaking - flocculation capture" is formed. The microjet generated by ultrasonic cavitation not only promotes the dispersion of ozone microbubbles (diameter <50μm), but also causes the hydrolysis products of polyaluminum chloride (PAC), Al... 13The formation rate is increased to over 75% (compared to only 40% by conventional methods). Simultaneously, the localized high-temperature environment during cavitation bubble collapse, combined with the catalytic effect of manganese dioxide, enhances the efficiency of ozone conversion into ·OH free radicals. This multi-effect synergistic mechanism enables a breakthrough COD removal rate of 90-95%, a 25-30% improvement over traditional segmented treatment processes. Furthermore, this invention employs an innovative "ultrasonic regulation / reagent sequential addition" model to construct an active floc structure with hierarchical pores: the initial stage uses high-energy ultrasound (0.6-1.0 W / mL) synergistically with polyaluminum chloride (PAC) to form charged micro-floc nuclei (50-100 nm); the middle stage maintains cavitation while adding polyacrylamide (CPAM) to form a "core-shell" structure with a pore size of 2-50 nm; the final stage reduces the frequency to 0.3-0.5 W / mL to maintain floc looseness. This structure has a specific surface area of ​​130-150 m² / g, which is 2-3 times that of traditional flocs.

[0005] To achieve these objectives and other advantages according to the present invention, a wastewater treatment method combining ultrasonic synergistic ozone catalytic oxidation and dynamic flocculation is provided, comprising the following steps: Step 1: Ozone (O3), nano-sized manganese dioxide, and polyaluminum chloride (PAC) are simultaneously added to the wastewater, and high-energy ultrasonic cavitation is applied. At the same time, the pH value is adjusted to 7 so that ozone oxidation and flocculation reaction can proceed simultaneously. The mass ratio of ozone to nano-sized manganese dioxide is 1:1~5, and the dosage of polyaluminum chloride (PAC) is 10~100mg / L. The high-energy ultrasonic cavitation generates local high temperature and pressure and microjets in the wastewater, accelerating the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, combined with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals; the power density of the high-energy ultrasonic waves is 0.6-1.0 W / mL. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al. 13 O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and continue to add cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.3~0.5W / mL and continue to act to degrade organic matter and maintain the looseness of the flocs; Step four: After the reaction is complete, stop the high-energy ultrasonic cavitation, allow it to settle, and separate the sludge from the water.

[0006] Preferably, the amount of ozone added is 5~30 mg / L.

[0007] Preferably, the ultrasonic treatment is performed in an intermittent mode or a continuous mode.

[0008] Preferably, the high-energy ultrasonic frequency in step one is 20~40kHz.

[0009] Preferably, the reaction time is 30-45 minutes.

[0010] This invention offers at least the following beneficial effects: by dynamically coupling ultrasonic cavitation, manganese dioxide catalytic oxidation, ozone advanced oxidation, and inorganic-organic composite flocculation, a synergistic chain of "cavitation degradation - catalytic oxidation bond breaking - flocculation capture" is formed. This multi-effect synergistic mechanism enables a breakthrough COD removal rate of 90-95%, which is 25-30% higher than traditional segmented treatment processes. Furthermore, this invention employs an innovative "ultrasonic regulation / reagent sequential addition" model to construct an active floc structure with hierarchical pores.

[0011] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0012] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0013] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0014] Example 1 Step 1: Add 50mg ozone (O3) (using an ozone generator), 200mg nano-sized manganese dioxide, and 100mg polyaluminum chloride (PAC) to 10L of industrial wastewater (COD: 2000mg / L), and apply high-energy ultrasonic cavitation at a frequency of 40kHz and a power density of 0.6W / mL. Simultaneously adjust the pH value to 7.0 and continue the reaction for 10 minutes to allow ozone oxidation and flocculation to proceed simultaneously. The high-energy ultrasonic cavitation generates local high temperature and pressure and micro-jet in the wastewater, which accelerates the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, in conjunction with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al. 13O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and simultaneously add 3 mg of cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.3 W / mL, and continue the reaction at a frequency of 20 kHz to degrade organic matter and maintain the looseness of the flocs; Step four: After a total reaction time of 45 minutes, the high-energy ultrasonic cavitation process is stopped, and the mixture is allowed to settle and separate the sludge from the clean water. The COD removal rate was measured to be 75%.

[0015] Example 2 Step 1: Add 50mg of ozone (O3) (using an ozone generator), 50mg of nano-sized manganese dioxide, and 100mg of polyaluminum chloride (PAC) to 10L of industrial wastewater (COD: 2000mg / L), and apply high-energy ultrasonic cavitation at a frequency of 40kHz and a power density of 0.6W / mL. Simultaneously adjust the pH value to 6.0 and continue the reaction for 10 minutes to allow ozone oxidation and flocculation to proceed simultaneously. The high-energy ultrasonic cavitation generates local high temperature and pressure and micro-jet in the wastewater, which accelerates the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, in conjunction with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al. 13 O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and simultaneously add 3 mg of cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.3W / mL and continue the reaction at a frequency of 20kHz. Use an intermittent working mode to degrade organic matter, working for 5 minutes and stopping for 2 minutes to maintain the looseness of the flocs. Step four, the reaction lasts for 45 minutes, after which the high-energy ultrasonic cavitation is stopped, the mixture is allowed to settle, and the sludge and water are separated. The COD removal rate is measured to be 85%.

[0016] Example 3 Step 1: Add 200mg ozone (O3) (using an ozone generator), 600mg nano-sized manganese dioxide, and 500mg polyaluminum chloride (PAC) to 10L of industrial wastewater (COD: 2000mg / L), and apply high-energy ultrasonic cavitation at a frequency of 50kHz and a power density of 0.8W / mL. Simultaneously adjust the pH value to 7.0 and continue the reaction for 8 minutes to allow ozone oxidation and flocculation to proceed simultaneously. The high-energy ultrasonic cavitation generates local high temperature and pressure and micro-jet in the wastewater, which accelerates the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, in conjunction with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al. 13 O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and simultaneously add 25 mg of cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.4 W / mL and continue the reaction at a frequency of 25 kHz. Use an intermittent working mode to degrade organic matter, working for 8 minutes and stopping for 3 minutes to maintain the looseness of the flocs. Step four: After a total reaction time of 30 minutes, the high-energy ultrasonic cavitation process is stopped, and the mixture is allowed to settle and separate the sludge from the clean water. The COD removal rate is measured to be 95%.

[0017] Example 4 Step 1: Add 300mg ozone (O3) (using an ozone generator), 1500mg nano-sized manganese dioxide, and 1000mg polyaluminum chloride (PAC) to 10L of industrial wastewater (COD: 2000mg / L), and apply high-energy ultrasonic cavitation at a frequency of 60kHz and a power density of 1W / mL. Simultaneously adjust the pH value to 8.0 and continue the reaction for 4 minutes to allow ozone oxidation and flocculation to proceed simultaneously. The high-energy ultrasonic cavitation generates local high temperature and pressure and micro-jet in the wastewater, which accelerates the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, in conjunction with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al.13 O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and simultaneously add 40 mg of cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.5W / mL and continue the reaction at a frequency of 30kHz. Use an intermittent working mode to degrade organic matter, working for 10 minutes and stopping for 2 minutes to maintain the looseness of the flocs. Step four: After a total reaction time of 40 minutes, the high-energy ultrasonic cavitation process is stopped, and the mixture is allowed to settle and separate the sludge from the clean water. The COD removal rate was found to be 88%.

[0018] Comparative Example Step 1: Add 200mg of ozone (O3) to 10L of industrial wastewater (COD: 2000mg / L) using an ozone generator to carry out ozone oxidation reaction on the wastewater; Step 2: Apply high-energy ultrasonic cavitation to the wastewater treated in Step 1. The frequency is 35kHz and the power density is 8W / mL. At the same time, adjust the pH value to 7.0. Step three: After a total reaction time of 90 minutes, the high-energy ultrasonic cavitation process is stopped, and the mixture is allowed to settle and separate the sludge from the clean water. The COD removal rate was measured to be 60%.

[0019] Compared with Example 3, Comparative Example 1 used a "series" of ozone oxidation followed by ultrasonic cavitation, without adding PAC-CPAM compound flocculant, nano-sized manganese dioxide catalytic oxidation, or intermittent ultrasonic treatment. This resulted in the dispersion of organic matter, making it impossible to form a core-shell structure with a large specific surface area. Furthermore, the lack of manganese dioxide catalytic oxidation led to a longer degradation time, a COD removal rate of only 60%, and a high sludge production.

[0020] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0021] As described above, this invention provides a wastewater treatment method that combines ultrasonic synergistic ozone catalytic oxidation and dynamic flocculation. By dynamically coupling ultrasonic cavitation effect, manganese dioxide catalytic oxidation, advanced ozone oxidation, and inorganic-organic composite flocculation, a synergistic chain of "cavitation degradation - catalytic oxidation bond breaking - flocculation capture" is formed. This multi-effect synergistic mechanism enables a breakthrough COD removal rate of 90-95%, which is 25-30% higher than traditional segmented treatment processes. Furthermore, this invention adopts an innovative mode of "ultrasonic regulation and sequential reagent addition" to construct an active floc structure with hierarchical pores.

[0022] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details shown and described herein.

Claims

1. A wastewater treatment method combining ultrasonic synergistic ozone catalytic oxidation and dynamic flocculation, characterized in that: The steps are as follows: Step 1: Ozone (O3), nano-sized manganese dioxide, and polyaluminum chloride (PAC) are simultaneously added to the wastewater, and high-energy ultrasonic cavitation is applied. At the same time, the pH value is adjusted to 7 so that ozone oxidation and flocculation reaction can proceed simultaneously. The mass ratio of ozone to nano-sized manganese dioxide is 1:1~5, and the dosage of polyaluminum chloride (PAC) is 10~100mg / L. The high-energy ultrasonic cavitation generates local high temperature and pressure and microjets in the wastewater, accelerating the dispersion of ozone microbubbles; when the cavitation bubbles generated by the high-energy ultrasonic cavitation collapse, the local high temperature environment, combined with the catalytic effect of the nano-sized manganese dioxide, improves the efficiency of ozone conversion into ·OH free radicals; the power density of the high-energy ultrasonic waves is 0.6-1.0 W / mL. The high-energy ultrasonic cavitation effect simultaneously promotes the hydrolysis of polyaluminum chloride (PAC) to generate highly positively charged Al. 13 O4(OH) 24 7 ⁺ Multinuclear complexes, which then form charged micro-floc nuclei; Step 2: Maintain the high-energy ultrasonic cavitation effect described in Step 1, and continue to add cationic polyacrylamide (CPAM) to the solution obtained in Step 1 to enhance floc formation and form a "core-shell" structure with a pore size of 2-50 nm. Step 3: Reduce the ultrasonic power density to 0.3~0.5W / mL and continue to act to degrade organic matter and maintain the looseness of the flocs; Step four: After the reaction is complete, stop the high-energy ultrasonic cavitation, allow it to settle, and separate the sludge from the water.

2. The wastewater treatment method according to claim 1, characterized in that, The amount of ozone added is 5~30 mg / L.

3. The wastewater treatment method according to claim 1, characterized in that, The ultrasonic treatment is performed in either intermittent or continuous mode.

4. The wastewater treatment method according to claim 1, characterized in that, In step one, the high-energy ultrasonic frequency is 20~40kHz.

5. The wastewater treatment method according to claim 1, characterized in that, The reaction time is 30-45 minutes.