Plasma hydrodynamic cavitation aeration coupled piezoelectric catalysis organic wastewater treatment system and method

Abstract

The invention discloses a plasma hydrodynamic cavitation aeration coupled piezoelectric catalysis organic wastewater treatment system and method. The system comprises a wastewater tank, a water pump, a Venturi tube hydrodynamic cavitator, a catalytic oxidation reactor, a piezoelectric particle separator, a piezoelectric catalytic particle bin, a low-temperature plasma generator and an air pump. By coupling piezoelectric catalysis, pressure pulsation mechanical energy generated by hydrodynamic cavitation is converted into chemical energy for driving the piezoelectric effect, on one hand, pollutants are directly oxidized, and on the other hand, plasma by-product H2O2 is efficiently converted into. OH with strong oxidizing property, so that cooperation with plasma advanced oxidation is formed, and the pollutant removal efficiency is improved. The pollutant degradation energy efficiency and the energy utilization rate of the system are greatly improved. Meanwhile, the system realizes efficient recovery and cyclic utilization of the magnetic piezoelectric catalytic particles through the magnetic separation type piezoelectric particle separator, so that secondary pollution of the catalyst is fundamentally avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic wastewater treatment, and particularly relates to a plasma-hydraulic cavitation-aeration coupled piezocatalytic organic wastewater treatment system and method. BACKGROUND

[0002] Industrial organic wastewater is widely generated in the industries of printing and dyeing, chemical industry, papermaking and pharmaceutical industry, and the non-degradable organic pollutants contained therein have negative effects on the environment and ecological health, and need to be subjected to advanced oxidation related processes for deep oxidation and degradation. As an efficient and green advanced oxidation process, low-temperature plasma technology can rapidly and deeply degrade organic pollutants in the treatment of organic wastewater. In the process of low-temperature plasma advanced oxidation, plasma is generated by exciting gas through high voltage, and high-energy electrons in the plasma generate oxidation active particles (·OH, ·O2 - , O3, H2O2) at the liquid interface to participate in the degradation of organic pollutants in water. However, the energy efficiency of the low-temperature plasma water treatment system in degrading organic pollutants still needs to be improved. The mass transfer and reaction of oxidation active particles are the key bottlenecks that inhibit the energy efficiency of plasma advanced oxidation.

[0003] By introducing a Venturi tube hydraulic cavitation device in front of the plasma bubble oxidation reactor, plasma micro-bubbles are generated by cavitation effect, and are forced to flow into the oxidation reactor with wastewater, which helps to strengthen the gas-liquid multiphase transfer and advanced oxidation in the reactor, thereby improving the energy efficiency of low-temperature plasma in treating organic wastewater. However, the hydraulic cavitation effect is generated by water pump driving, accompanied by a large amount of mechanical energy dissipation, and the consumption of water pump mechanical energy will offset a part of the energy efficiency of organic pollutant degradation improved by hydraulic cavitation, so that the energy efficiency of low-temperature plasma in degrading organic pollutants under the action of hydraulic cavitation is not effectively improved. At the same time, the weak oxidant H2O2 generated by plasma bubbles in the process of organic wastewater does not effectively participate in the advanced oxidation of organic wastewater, so that the energy efficiency of low-temperature plasma advanced oxidation still needs to be improved. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide a plasma-hydraulic cavitation-aeration coupled piezocatalytic organic wastewater treatment system and method, which can improve the degradation efficiency of organic pollutants and the overall energy efficiency of the system, and realize rapid and efficient recovery and recycling of the catalyst after the reaction, thereby avoiding secondary pollution.

[0005] The present application constructs a plasma-piezocatalytic composite advanced oxidation system by mixing piezocatalytic particles in organic wastewater, and drives the piezocatalytic particles to generate piezoelectric effect by the hydraulic mechanical energy of hydraulic cavitation wave and bubble flow, so that electrons e - and holes h + are generated on the surface of the piezocatalytic particles, and the holes h +Directly oxidize and degrade organic matter, electron e - The weak oxidizing H2O2 can be converted into strong oxidizing ·OH to degrade organic pollutants, thereby efficiently recycling and utilizing the hydraulic mechanical energy of the system and improving the degradation efficiency of the system on the organic pollutants. Meanwhile, by synthesizing the magnetic piezoelectric catalytic particles Fe3O4-BaTiO3 and introducing the piezoelectric catalytic particle recycler, the piezoelectric catalytic particles can be efficiently recycled and utilized, thereby assisting the efficient degradation of industrial organic wastewater.

[0006] The application achieves the above purposes through the following technical solutions: The application achieves the above purposes through the following technical solutions: The first water outlet of the wastewater tank is connected with the water inlet of the water pump, the water outlet of the water pump is connected with the water inlet of the Venturi tube hydraulic cavitation device, the water outlet of the Venturi tube hydraulic cavitation device is connected with the bottom of the catalytic oxidation reactor, and the top gas outlet of the catalytic oxidation reactor is connected with the ozone decomposer; the water outlet of the catalytic oxidation reactor is connected with the first interface of the first three-way valve, the second interface of the first three-way valve is connected with the first interface of the second three-way valve, and the second interface of the second three-way valve is connected with the water inlet of the wastewater tank. The air pump is connected with the air inlet of the low-temperature plasma generator, and the air outlet of the low-temperature plasma generator is connected with the air inlet of the throat of the Venturi tube hydraulic cavitation device. The water inlet of the piezoelectric particle separator is connected with the third interface of the first three-way valve, the water outlet of the piezoelectric particle separator is connected with the third interface of the second three-way valve, the particle outlet of the piezoelectric particle separator is connected with the material inlet of the piezoelectric catalytic particle bin, and the material outlet of the piezoelectric catalytic particle bin is connected with the wastewater tank through the feeding pipe.

[0007] In the above scheme, the piezoelectric particle separator is a magnetic separation device, which comprises a fan-shaped flow channel, a magnetic rotating cylinder and a scraper; the magnetic rotating cylinder is arranged in the fan-shaped flow channel of the piezoelectric particle separator and is arranged with the same center as the flow channel, and is used for adsorbing magnetic piezoelectric catalytic particles; the scraper is arranged on one side of the magnetic rotating cylinder, the piezoelectric particle outlet of the piezoelectric particle separator is guided by the scraper and connected with the piezoelectric catalytic particle bin, and is used for scraping off the adsorbed particles and guiding them to the piezoelectric catalytic particle bin.

[0008] In the above scheme, the Venturi tube hydraulic cavitation device and the catalytic oxidation reactor are connected through flanges or threads; the number of the Venturi tube hydraulic cavitation devices is one or more; and the bottom cross-sectional area of the catalytic oxidation reactor is 3-10 times the total area of the outlets of all the Venturi tube hydraulic cavitation devices.

[0009] The water flow Reynolds number of the throat of the Venturi tube hydraulic cavitation device is 20000-25000, and the flow ratio of the gas and liquid flowing into the throat is 1:10-1:4.

[0010] In the above scheme, the gas flow channel of the low-temperature plasma generator is made of quartz glass; the high-voltage electrode is arranged in the center of the gas flow channel in the axial direction, and the grounding electrode is wrapped outside the outer wall of the gas flow channel; the discharge annular gap between the high-voltage electrode and the grounding electrode is 3-5 mm.

[0011] A method for treating organic wastewater by using the organic wastewater treatment system coupling the plasma hydraulic cavitation aeration and the piezocatalysis, comprising the following steps: Step S1, mixing the piezocatalytic particles in the piezocatalytic particle bin with the organic wastewater in the wastewater tank, and pumping the organic wastewater mixture with suspended piezocatalytic particles into the Venturi tube hydraulic cavitation device by a water pump; Step S2, starting the air pump and the low-temperature plasma generator, converting the air into low-temperature plasma, and then introducing the low-temperature plasma into the throat of the Venturi tube hydraulic cavitation device to mix with the liquid to form plasma micro-bubbles; Step S3, the mixture carrying the plasma micro-bubbles enters the catalytic oxidation reactor to perform oxidation degradation reaction; Step S4, the gas after reaction in the catalytic oxidation reactor is discharged through the ozone decomposer, and the liquid after reaction flows back to the wastewater tank through the first three-way valve and the second three-way valve; Step S5, repeating steps S1-S4 until the degradation degree of the organic pollutants reaches the expectation; Step S6, when the degradation degree reaches the expectation, switching the first three-way valve and the second three-way valve to guide the liquid after reaction to the piezoelectric particle separator to separate and recover the piezocatalytic particles, and discharging the treated liquid after separation from the system through the drain of the wastewater tank.

[0012] In the above scheme, the mixing concentration of the piezocatalytic particles in the organic wastewater is 0.2-1 g / L; and the discharge voltage of the low-temperature plasma generator is 7-10 kV.

[0013] In the above scheme, the piezocatalytic particles are Fe3O4-BaTiO3 composite materials with magnetism.

[0014] Further, the Fe3O4-BaTiO3 piezocatalytic particles are synthesized by one-step hydrothermal method, and the particle magnetization intensity is 50-100 emu / g, and the specific steps are as follows: 0.86 mmol Ba(OH)2·8H2O, 0.01 mol KOH and 0.03 g Fe3O4 particles with a particle size of 50 nm were added into a mixed solution of n-butanol and deionized water with a volume ratio of 1:1 in a volume of 60 mL, then 0.3 mL of tetrabutyl titanate was added dropwise and stirred for 30 minutes; the mixed solution was transferred to a hydrothermal reaction kettle and reacted at 180 DEG C for 10 hours; after the reaction was completed, the obtained solid product was washed repeatedly with ethanol and deionized water and dried under vacuum at room temperature, thereby obtaining Fe3O4-BaTiO3 magnetic piezocatalytic particles.

[0015] In the above scheme, in steps S1 to S4, the pressure fluctuation generated by the operation of the Venturi tube hydrodynamic cavitation device has a pressure greater than 1 kPa and a frequency of 10 Hz to 500 Hz, which is used to drive the piezocatalytic particles to generate piezoelectric effect.

[0016] In the above scheme, in step S5, the degradation degree is evaluated by sampling monitoring, including: periodically sampling from the wastewater tank, measuring the pH value, conductivity and COD value of the treatment liquid, and judging whether the expected degradation target is reached according to the measurement results.

[0017] Compared with the prior art, the present application has the following technical effects: 1. The present application realizes efficient degradation of organic pollutants through the synergistic effect of plasma oxidation and piezocatalysis. As shown in the examples, compared with a single plasma hydrodynamic cavitation system, the degradation rate of methylene blue is increased from 75.5% to 89.3% (at 60 minutes).

[0018] 2. The present application recycles the hydraulic mechanical energy originally dissipated in the system into chemical energy to drive piezoelectric effect, and "turns waste into treasure" by using byproduct H2O2, which significantly improves energy utilization efficiency. At the same degradation rate, the energy efficiency of the present application can reach 1.7 times that of a single plasma system (see the results of Example 1 and Example 2 for comparison).

[0019] 3. The present application realizes nearly 100% recovery and recycling of the catalyst by using magnetic Fe3O4-BaTiO3 particles and a magnetic separator, which fundamentally eliminates the secondary pollution problem caused by catalyst loss and reduces operating costs.

[0020] 4. The present application can realize seamless conversion between "reaction mode" and "recovery mode" through valve switching, and has a compact system flow and high degree of automation, which has good industrial application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the plasma hydrodynamic cavitation aeration coupled piezocatalytic organic wastewater treatment system of the present application. Figure 2 Figure is the degradation rate diagram of the organic wastewater treated by the plasma hydrodynamic cavitation aeration coupled piezocatalysis of the application; Figure 3 Figure is the energy efficiency diagram of the organic wastewater treated by the plasma hydrodynamic cavitation aeration coupled piezocatalysis of the application; The labels in the figure are as follows: 1, organic wastewater; 2, wastewater tank; 3, stirrer; 4, water pump; 5, Venturi tube hydrodynamic cavitation device; 6, catalytic oxidation reactor; 7, ozone decomposer; 8, tail gas; 9, first three-way valve; 10, second three-way valve; 11, piezoelectric particle separator; 12, magnetic rotating drum; 13, scraper; 14, piezocatalytic particle bin; 15, feeding pipe; 16, water outlet; 17, air; 18, air pump; 19, low-temperature plasma generator; 20, high-voltage power supply; 21, high-voltage electrode; 22, grounding electrode; 23, low-temperature plasma bubble; 24, piezoelectric particle. DETAILED DESCRIPTION

[0022] The embodiments of the application are described in detail below, The embodiments of the application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application. Example 1

[0023] A plasma hydrodynamic cavitation aeration coupled piezocatalysis organic wastewater treatment system, comprising a wastewater tank 2, a Venturi tube hydrodynamic cavitation device 5, a catalytic oxidation reactor 6, a piezoelectric particle separator 11, a piezocatalytic particle bin 14 and a low-temperature plasma generator 19; The first water outlet of the wastewater tank 2 is connected with the water inlet of the water pump 4, the water outlet of the water pump 4 is connected with the water inlet of the Venturi tube hydrodynamic cavitation device 5, the water outlet of the Venturi tube hydrodynamic cavitation device 5 is connected with the bottom of the catalytic oxidation reactor 6, and the top gas outlet of the catalytic oxidation reactor 6 is connected with the ozone decomposer 7; the water outlet of the catalytic oxidation reactor 6 is connected with the first interface of the first three-way valve 9, the second interface of the first three-way valve 9 is connected with the first interface of the second three-way valve 10, the second interface of the second three-way valve 10 is connected with the water inlet of the wastewater tank 2, and after the treatment of the wastewater tank (2) is completed and reaches the standard, the treated water (16) in the wastewater tank (2) flows out through the water outlet The air outlet of the air pump 18 is connected with the air inlet of the low-temperature plasma generator 19, and the air outlet of the low-temperature plasma generator 19 is connected with the air inlet of the throat of the Venturi tube hydrodynamic cavitation device 5; The water inlet of the piezoelectric particle separator 11 is connected with the third interface of the first three-way valve 9, the water outlet of the piezoelectric particle separator 11 is connected with the third interface of the second three-way valve 10, the particle outlet of the piezoelectric particle separator 11 is connected with the material inlet of the piezoelectric catalytic particle bin 14, and the material outlet of the piezoelectric catalytic particle bin 14 is connected with the piezoelectric particle feeding inlet of the wastewater tank 2 through the feeding pipe 15.

[0024] The organic wastewater 1 to be treated is placed in the wastewater tank 2, the piezoelectric catalytic particles 24 in the piezoelectric catalytic particle bin 14 are poured into the organic wastewater 1 in a certain mass ratio through the feeding pipe 15, and are uniformly mixed through the stirrer 3; the organic wastewater 1 carrying the piezoelectric catalytic particles 24 flows into the Venturi tube hydrodynamic cavitation device 5 driven by the water pump 4; the air 17 flows through the low-temperature plasma generator 19 driven by the air pump 18, and flows into the Venturi tube hydrodynamic cavitation device 5 after being converted into low-temperature plasma by discharge between the high-voltage electrode 21 powered by the high-voltage power supply 20 and the grounding electrode 22; the low-temperature plasma bubbles 23 generated by the hydrodynamic cavitation of the Venturi tube hydrodynamic cavitation device 5 produce active oxidative substances ROS (·OH, ·O2 - , O3, H2O2) in the catalytic oxidation reactor 6 to oxidatively degrade the organic matter in the water; at the same time, the piezoelectric particles 24 suspended in the water generate electrons e - and holes h + on the surface of the particles under the action of the pressure pulsation caused by the hydrodynamic cavitation and bubble flow, wherein the holes h + directly oxidatively degrade the organic matter, and the electrons e - convert the weakly oxidizing H2O2 into the strongly oxidizing ·OH to further oxidatively degrade the organic pollutants; the gas in the catalytic oxidation reactor 6 flows out of the system through the ozone decomposer 7, and the organic wastewater 1 carrying the piezoelectric catalytic particles 24 flows back to the wastewater tank 2 through the first three-way valve 9 and the second three-way valve 10 after the reaction, so as to perform a cycle reaction. When the reaction is completed, the organic wastewater 1 carrying the piezoelectric catalytic particles 24 flows into the piezoelectric particle separator 11 through the first three-way valve 9 to separate and recover the piezoelectric particles into the piezoelectric catalytic particle bin 14, and the treatment liquid flows back to the wastewater tank 2 through the second three-way valve 10; the treated water flows out through the water outlet 16 after the reaction is completed.

[0025] The piezoelectric particle separator 11 is a magnetic separation device, which comprises a fan-shaped flow channel, a magnetic rotating drum 12 and a scraper 13; the magnetic rotating drum 12 is arranged in the fan-shaped flow channel of the piezoelectric particle separator 11 and is arranged with the flow channel as the same center, and is used for adsorbing the magnetic piezoelectric catalytic particles 24; the scraper 13 is arranged on one side of the magnetic rotating drum 12, the piezoelectric particle outlet of the piezoelectric particle separator 11 is guided through the scraper 13 and connected with the piezoelectric catalytic particle bin 14, and is used for scraping off the adsorbed particles and guiding them to the piezoelectric catalytic particle bin 14.

[0026] The magnetic rotating drum 12 is equipped with a permanent magnet or electromagnet inside, which generates a magnetic field during rotation to adsorb magnetic piezoelectric catalytic particles 24 in wastewater. When the magnetic rotating drum 12 with attached particles rotates to the non-magnetic field area, it is scraped off by the scraper 13 and falls into the hopper 14.

[0027] The Venturi tube hydraulic cavitation device 5 is connected to the catalytic oxidation reactor 6 via a flange or thread; the number of Venturi tube hydraulic cavitation devices 5 is one or more, depending on the size of the bottom cross-sectional area of ​​the catalytic oxidation reactor 6; the bottom cross-sectional area of ​​the catalytic oxidation reactor 6 can be 3 to 10 times the total outlet area of ​​all Venturi tube hydraulic cavitation devices 5.

[0028] The Reynolds number of the water flow in the throat of the Venturi tube hydraulic cavitation device 5 ranges from 20,000 to 25,000, and the flow ratio of gas to liquid entering its throat is 1:10 to 1:4.

[0029] The gas flow channel of the low-temperature plasma generator 19 is made of quartz glass; the high-voltage electrode 21 is axially disposed at the center of the gas flow channel, and the ground electrode 22 is a stainless steel wire mesh covering the outer wall of the gas flow channel; the discharge annular gap between the high-voltage electrode 21 and the ground electrode 22 is 3 to 5 mm.

[0030] The connecting pipe between the catalytic oxidation reactor 6, the piezoelectric particle separator 11, and the wastewater tank 2 is equipped with a first three-way valve 9 and a second three-way valve 10. The opening and closing direction of the valves can be adjusted to control whether the organic wastewater 1 containing suspended piezoelectric particles 24 flows directly from the catalytic oxidation reactor 6 into the wastewater tank 2, or whether the organic wastewater 1 containing suspended piezoelectric particles 24 flows through the piezoelectric particle separator 11 to separate and recover the piezoelectric particles 24 before flowing into the wastewater tank 2.

[0031] The piezoelectric catalytic particles 24 are mixed with organic wastewater 1 at a concentration of 0.2~1 g / L, and the discharge voltage of the high-voltage power supply 20 is 7~10 kV. While the organic wastewater in the catalytic oxidation reactor 6 is being degraded by low-temperature plasma bubbles 23, the generated weak oxide H2O2 helps promote the catalytic oxidation degradation of organic pollutants by the piezoelectric particles. The introduction of the piezoelectric catalytic particles effectively utilizes the hydraulic mechanical energy of the system; the pressure pulsation caused by hydraulic cavitation and bubble flow provides an effective driving force for the suspended piezoelectric catalytic particles. Under the operating conditions of the Venturi tube hydraulic cavitation device 5 (the Reynolds number of the water flow in the throat of the Venturi tube hydraulic cavitation device 5 ranges from 20000 to 25000, and the flow ratio of gas to liquid entering its throat is 1:10 to 1:4), the pressure pulsation generated is sufficient to drive the piezoelectric catalytic particles 24 to produce a piezoelectric effect. When the pressure of the pressure pulsation is greater than 1 kPa and the frequency is in the range of 10 Hz to 500 Hz, an effective piezoelectric catalytic effect can be achieved.

[0032] The piezoelectric catalytic particles 24 are magnetic Fe3O4-BaTiO3 composite materials; the Fe3O4-BaTiO3 particles mainly consist of BaTiO3 particles supported on Fe3O4 spherical particles, with the Fe3O4 spherical particles having a particle size of approximately 50 nm and the BaTiO3 particles having a particle size of 10 nm; the particle magnetization is 50-100 emu / g; the Fe3O4-BaTiO3 piezoelectric catalytic particles are synthesized via a one-step hydrothermal method, with the specific steps as follows: 0.86 mmol Ba(OH)₂8H₂O, 0.01 mol KOH, and 0.03 g Fe₃O₄ particles with a diameter of 50 nm were added to 60 mL of a 1:1 mixture of n-butanol and deionized water. Then, 0.3 mL of tetrabutyl titanate was added dropwise and the mixture was stirred for 30 minutes. The mixture was then transferred to a hydrothermal reactor and reacted at 180 °C for 10 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting solid product was repeatedly washed with ethanol and deionized water and then dried under vacuum at room temperature to obtain Fe₃O₄-BaTiO₃ magnetic piezoelectric catalytic particles.

[0033] This invention enables the efficient use of hydraulic mechanical energy to generate piezoelectric catalytic oxidation reactions to degrade organic pollutants in a plasma-hydraulic cavitation aeration advanced oxidation system for organic wastewater treatment. This is achieved by coupling piezoelectric catalytic reactions and recovering magnetic piezoelectric particles. Simultaneously, the piezoelectric catalysis converts the weak oxide H₂O₂ generated by low-temperature plasma discharge into the strong oxide ·OH for further oxidative degradation of organic pollutants, thus improving the efficiency of low-temperature plasma organic pollutant degradation. Furthermore, the introduction of a piezoelectric particle separator utilizes a magnetic rotating drum to efficiently recover the magnetic piezoelectric particles, effectively avoiding secondary catalyst pollution caused by the piezoelectric catalytic particles.

[0034] This invention can effectively improve the energy efficiency and organic wastewater degradation efficiency of low-temperature plasma advanced oxidation, and at the same time provide an effective technical solution for the hydraulic mechanical energy driven piezoelectric catalytic oxidation degradation of organic pollutants in advanced oxidation systems for organic wastewater.

[0035] Figure 1 This is a schematic diagram of the plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system of the present invention. The organic wastewater 1 is a methylene blue solution with a concentration of 25 mg / L and a volume of 2.6 L. The concentration of Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles in the wastewater during the reaction process is 0.4 g / L, and the reaction temperature is room temperature.

[0036] The method for treating organic wastewater using the plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system includes the following steps: Step S1: The piezoelectric catalytic particles in the piezoelectric catalytic particle hopper 14, which have reached adsorption-desorption equilibrium with organic pollutants, are mixed with the organic wastewater 1 to be degraded in the wastewater tank 2 at a concentration ratio of 0.4 g / L via the feeding pipe 15. The organic wastewater 1 with suspended piezoelectric catalytic particles 24 is then pumped into the Venturi tube hydraulic cavitation device 5 at a flow rate of 3.5 L / min via the water pump 4. Step S2: Air 17 enters the low-temperature plasma generator 19 through air pump 18 at a flow rate of 1 L / min. The discharge power of the high-voltage power supply 20 connected to the high-voltage electrode 21 is adjusted to 70W and the discharge voltage is 7 kV. Air 17 is excited into low-temperature plasma between the high-voltage electrode 21 and the ground electrode 22. It is introduced into the Venturi tube hydraulic cavitation device 5 to undergo hydraulic cavitation and disperse into plasma bubbles 23. Step S3: Organic wastewater 1 containing suspended piezoelectric catalytic particles 24, carrying plasma bubbles 23, flows into catalytic oxidation reactor 6 for the degradation of organic pollutants; In step S4, the gas after reaction in the catalytic oxidation reactor 6 is discharged from the system through the ozone decomposer 7, and the organic wastewater 1 containing suspended piezoelectric catalytic particles flows back to the wastewater tank 2 through the first three-way valve 9 and the second three-way valve 10. Step S5: Repeat steps S1 to S4 until the degradation degree of organic pollutants reaches the expected level. In step S5, the degradation degree is assessed by sampling and monitoring, including: periodically sampling from wastewater tank 2 to measure the pH, conductivity, and COD of the treated liquid, and judging whether the expected degradation degree has been reached based on the measurement results. Specifically, the treated liquid flowing back to wastewater tank 2 is sampled to measure the pH, conductivity, and COD of the treated liquid; 3 mL samples are taken every 10 minutes to measure the pH, conductivity, COD, and pollutant concentration of organic wastewater 16. The pH of the wastewater is measured using a pH meter, the conductivity is measured using a conductivity meter, the COD is measured using a COD meter, and the absorbance of the methylene blue solution is measured using a spectrophotometer. The concentration of methylene blue in the solution is calculated using the standard relationship curve between the concentration of methylene blue solution and absorbance. The methylene blue solution concentration c (mg / L) and absorbance OD are compared. 665nm The standard curve, and its formula, are as follows:

[0037] The measurement results are compared with national standards to determine whether the treated liquid meets the discharge standards. If it does not meet the standards, steps S1-S4 are repeated to continue the circulation treatment. At the same time, H2O2, acid-base regulators and other reagents can be added to wastewater tank 2 to optimize the reaction conditions. According to the treatment requirements of anionic surfactant (methylene blue), when the concentration of methylene blue is less than 5 mg / L, it is judged to meet the standards. Step S6: When the degradation reaches the expected level, switch the first three-way valve 9 and the second three-way valve 10 to guide the reaction liquid to the piezoelectric particle separator 11 to separate and recover the piezoelectric catalytic particles 24. The separated treatment liquid 16 is discharged from the system through the drain outlet of the wastewater tank 2. Example 2

[0038] A method for treating organic wastewater using a plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system is disclosed. This embodiment differs from Embodiment 1 in that it does not couple with piezoelectric catalysis, does not mix Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles into the organic wastewater, and the reaction temperature is room temperature. The method includes the following steps: Step S1: The organic wastewater 1 in the wastewater tank 2 is pumped into the Venturi tube hydraulic cavitation device 5 at a flow rate of 3.5 L / min by the water pump 4. Step S2: Air 17 enters the low-temperature plasma generator 19 through air pump 18 at a flow rate of 1 L / min. The discharge power of the high-voltage power supply 20 connected to the high-voltage electrode 21 is adjusted to 70W and the discharge voltage is 7 kV. Air 17 is excited into low-temperature plasma between the high-voltage electrode 21 and the ground electrode 22. It is introduced into the Venturi tube hydraulic cavitation device 5 to undergo hydraulic cavitation and disperse into plasma bubbles 23. Step S3: Organic wastewater 1 carrying plasma bubbles 23 flows into catalytic oxidation reactor 6 for the degradation of organic pollutants; In step S4, the gas after reaction in the catalytic oxidation reactor 6 is discharged from the system through the ozone digester 7, and the organic wastewater 1 flows back to the wastewater tank 2 through the first three-way valve 9 and the second three-way valve 10. Step S5: Sample the treated liquid flowing back to wastewater tank 2 and measure its pH, conductivity, and COD. Take 3 mL samples every 10 minutes to measure the pH, conductivity, COD, and pollutant concentration of organic wastewater 16. The experiment uses a pH meter to measure the pH of the wastewater, a conductivity meter to measure the conductivity, a COD meter to measure the COD, and a spectrophotometer to measure the absorbance of the methylene blue solution. The concentration of methylene blue in the solution is calculated using the standard curve of methylene blue solution concentration versus absorbance. The methylene blue solution concentration c (mg / L) is compared with the absorbance OD. 665nm The standard curve, and its formula, are as follows:

[0039] The measurement results are compared with the national standard to determine whether the treated liquid meets the discharge standard. If it does not meet the standard, steps S1-S5 are repeated to continue the circulation treatment. At the same time, H2O2, acid-base regulators and other reagents can be added to wastewater tank 2 to optimize the reaction conditions. Step S6: Once the standard is met, the treatment is complete, and the treated liquid 16 flows out of the system through the drain outlet of the wastewater tank. (Measurements showed that in Example 2, the degradation rate was 75.5% after 60 minutes of reaction, and the concentration dropped to 6.125 mg / L. Since the standard was not met within 60 minutes, continued energy-consuming recycling treatment is required to achieve the standard. Once the standard is met, the treatment is complete, and the treated liquid 16 flows out of the system through the drain outlet of the wastewater tank.) Example 3

[0040] The plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system includes the following steps: A method for treating organic wastewater using plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis is disclosed in this embodiment, which differs from Embodiment 1 in that the low-temperature plasma generator 19 is not operational, meaning the bubbles 23 generated by the hydraulic cavitation aeration are air bubbles. Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles are mixed into the organic wastewater for separate piezoelectric catalytic oxidation without the addition of H2O2 to assist the reaction. The reaction temperature is room temperature. The method includes the following steps: Step S1: The piezoelectric catalytic particles in the piezoelectric catalytic particle hopper 14, which have reached adsorption-desorption equilibrium with organic pollutants, are mixed with the organic wastewater 1 to be degraded in the wastewater tank 2 at a concentration ratio of 0.4 g / L via the feeding pipe 15. The organic wastewater 1 with suspended piezoelectric catalytic particles is then pumped into the Venturi tube hydraulic cavitation device 5 at a flow rate of 3.5 L / min via the water pump 4. Step S2: Air 17 is introduced into the Venturi tube hydraulic cavitation device 5 through air pump 18 at a flow rate of 1 L / min, where it undergoes hydraulic cavitation and disperses into plasma bubbles 23. Step S3: Organic wastewater 1 containing suspended piezoelectric catalytic particles carries plasma bubbles 23 into catalytic oxidation reactor 6 for the degradation of organic pollutants; In step S4, the gas after reaction in the catalytic oxidation reactor 6 is discharged from the system through the ozone decomposer 7, and the organic wastewater 1 containing suspended piezoelectric catalytic particles flows back to the wastewater tank 2 through the first three-way valve 9 and the second three-way valve 10. Step S5: Sample the treated liquid flowing back to wastewater tank 2 and measure its pH, conductivity, and COD. Take 3 mL samples every 10 minutes to measure the pH, conductivity, COD, and pollutant concentration of organic wastewater 16. The experiment uses a pH meter to measure the pH of the wastewater, a conductivity meter to measure the conductivity, a COD meter to measure the COD, and a spectrophotometer to measure the absorbance of the methylene blue solution. The concentration of methylene blue in the solution is calculated using the standard curve of methylene blue solution concentration versus absorbance. The methylene blue solution concentration c (mg / L) is compared with the absorbance OD. 665nm The standard curve, and its formula, are as follows:

[0041] The measurement results are compared with national standards to determine whether the treated liquid meets the emission standards. If it does not meet the standards, steps S1-S4 are repeated to continue the circulation treatment. Step S6: If the standard is met, the treatment is complete; or, if the degradation rate stops increasing, the treatment is stopped. The organic wastewater containing suspended piezoelectric particles 24 in the catalytic oxidation reactor 6 flows through the piezoelectric particle separator 11 to separate and recover the piezoelectric particles 24 before flowing into the wastewater tank 2; the treated liquid 16 flows out of the system through the drain outlet of the wastewater tank. (Measurements showed that after 60 minutes of reaction in Example 3, the methylene blue degradation rate was 14.5%, which is very low, with the concentration dropping to 21.375 mg / L, clearly failing to meet the standard.) The apparatus of Examples 1, 2, and 3 were used to treat organic wastewater according to the methods described in Examples 1, 2, and 3. The experiment was repeated three times, and the results are as follows: Figure 2 and Figure 3 As shown, Figure 2 This is a graph showing the degradation rate of organic wastewater by plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis according to the present invention. Figure 3 This is a diagram illustrating the energy efficiency of plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis for the degradation of organic wastewater according to the present invention.

[0042] The organic wastewater is a methylene blue solution with a concentration of 25 mg / L and a volume of 2.6 L. The concentration of Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles in the wastewater during the reaction process is 0.4 g / L, and the reaction temperature is room temperature.

[0043] Depend on Figure 2 It can be seen that after 60 minutes of treatment, the degradation rate of methylene blue using the device in Example 1 reached 89.3%. After 60 minutes of treatment using the device in Example 2, the degradation rate of methylene blue reached 75.5%, while the degradation rate of methylene blue using the device in Example 3 reached 14.5% after 60 minutes. Example 1 (plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis): The degradation rate of methylene blue reached 89.3% after 60 minutes. This degradation rate is relatively high, indicating that the emission standard was met within 60 minutes. The national standard requires the methylene blue concentration to be below 5 mg / L (80% degradation from an initial 25 mg / L), so a degradation rate of 89.3% (concentration reduced to 2.675 mg / L) meets the standard. Example 2 (without coupled piezoelectric catalysis): The degradation rate was 75.5% after 60 minutes, and the concentration decreased to 6.125 mg / L, failing to meet the standard within 60 minutes, requiring continued energy-consuming cycle treatment to meet the standard. Example 3 (piezoelectric catalysis only, without plasma): The degradation rate was 14.5% after 60 minutes. The degradation rate was very low, with the concentration dropping to 21.375 mg / L, which clearly did not meet the standard and required a longer cycle time to achieve it. This demonstrates the synergistic effect of the coupled piezoelectric catalysis and the energy-saving advantages of energy recovery and utilization in this invention.

[0044] Depend on Figure 3 It can be seen that the device in Example 1 has a degradation efficiency of 729 mg / kWh when the degradation rate is 60%, which is 1.7 times that of Example 2 (428 mg / kWh).

[0045] This invention constructs a plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis for the advanced oxidation of organic wastewater, simultaneously coupling piezoelectric catalytic reactions and achieving the separation and recovery of magnetic piezoelectric particles. By introducing Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles into the plasma advanced oxidation system, organic pollutants are degraded by low-temperature plasma bubble advanced oxidation. Simultaneously, the hydraulic mechanical energy of cavitation and bubble flow is efficiently utilized to generate piezoelectric catalytic oxidation reactions to degrade organic pollutants. Furthermore, piezoelectric catalysis can convert the weak oxide H2O2 generated by low-temperature plasma discharge into the strong oxide ·OH for the oxidation and degradation of organic pollutants. This achieves efficient participation of wastewater hydraulic mechanical energy in the advanced oxidation of organic pollutants, improving the energy efficiency of low-temperature plasma organic pollutant degradation.

[0046] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0047] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis for treating organic wastewater, characterized in that, It includes a wastewater tank (2), a venturi tube hydraulic cavitation device (5), a catalytic oxidation reactor (6), a piezoelectric particle separator (11), a piezoelectric catalytic particle silo (14), and a low-temperature plasma generator (19). The first outlet of the wastewater tank (2) is connected to the inlet of the water pump (4), the outlet of the water pump (4) is connected to the inlet of the Venturi tube hydraulic cavitation device (5), the outlet of the Venturi tube hydraulic cavitation device (5) is connected to the bottom of the catalytic oxidation reactor (6), and the top outlet of the catalytic oxidation reactor (6) is connected to the ozone decomposer (7); the outlet of the catalytic oxidation reactor (6) is connected to the first port of the first three-way valve (9), the second port of the first three-way valve (9) is connected to the first port of the second three-way valve (10), and the second port of the second three-way valve (10) is connected to the inlet of the wastewater tank (2); The air outlet of the air pump (18) is connected to the air inlet of the low-temperature plasma generator (19), and the air outlet of the low-temperature plasma generator (19) is connected to the air inlet of the throat of the Venturi tube hydraulic cavitation device (5). The inlet of the piezoelectric particle separator (11) is connected to the third interface of the first three-way valve (9), the outlet of the piezoelectric particle separator (11) is connected to the third interface of the second three-way valve (10), the particle outlet of the piezoelectric particle separator (11) is connected to the inlet of the piezoelectric catalytic particle silo (14), and the outlet of the piezoelectric catalytic particle silo (14) is connected to the wastewater tank (2) through the feeding pipe (15).

2. The plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system according to claim 1, characterized in that, The piezoelectric particle separator (11) is a magnetic separator, including a fan-shaped flow channel, a magnetic rotating drum (12) and a scraper (13); the magnetic rotating drum (12) is arranged in the fan-shaped flow channel of the piezoelectric particle separator (11) and is arranged in the same circle as the flow channel, and is used to adsorb magnetic piezoelectric catalytic particles (24); the scraper (13) is arranged on one side of the magnetic rotating drum (12), and the piezoelectric particle outlet of the piezoelectric particle separator (11) is guided by the scraper (13) to connect to the piezoelectric catalytic particle hopper (14), and is used to scrape off the adsorbed particles and guide them to the piezoelectric catalytic particle hopper (14).

3. The plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system according to claim 1, characterized in that, The Venturi tube hydraulic cavitation device (5) is connected to the catalytic oxidation reactor (6) by a flange or thread; the number of Venturi tube hydraulic cavitation devices (5) is one or more; the bottom cross-sectional area of ​​the catalytic oxidation reactor (6) is 3 to 10 times the total outlet area of ​​all Venturi tube hydraulic cavitation devices (5).

4. The plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system according to claim 1, characterized in that, The Reynolds number of the water flow in the throat of the Venturi tube hydraulic cavitation device (5) ranges from 20,000 to 25,000, and the flow ratio of gas to liquid entering its throat is 1:10 to 1:

4.

5. The plasma-hydraulic cavitation aeration coupled with piezoelectric catalysis organic wastewater treatment system according to claim 1, characterized in that, The gas flow channel of the low-temperature plasma generator (19) is made of quartz glass; the high-voltage electrode (21) is arranged axially at the center of the gas flow channel, and the ground electrode (22) covers the outer wall of the gas flow channel; the discharge annular gap between the high-voltage electrode (21) and the ground electrode (22) is 3 to 5 mm.

6. A method for treating organic wastewater using the plasma-hydraulic cavitation aeration coupled with piezoelectric catalytic organic wastewater treatment system as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: Mix the piezoelectric catalytic particles (24) in the piezoelectric catalytic particle silo (14) with the organic wastewater (1) in the wastewater tank (2), and pump the mixture of suspended piezoelectric catalytic particles (24) and organic wastewater (1) into the Venturi tube hydraulic cavitation device (5) by the water pump (4). Step S2: Start the air pump (18) and the low-temperature plasma generator (19) to convert the air into low-temperature plasma and then introduce it into the throat of the Venturi tube hydraulic cavitation device (5) to mix with the liquid and form plasma microbubbles (23). Step S3: The mixture carries the plasma microbubbles (23) into the catalytic oxidation reactor (6) for oxidation degradation reaction; Step S4: The gas after reaction in the catalytic oxidation reactor (6) is discharged through the ozone decomposer (7), and the liquid after reaction flows back to the wastewater tank (2) through the first three-way valve (9) and the second three-way valve (10). Step S5: Repeat steps S1 to S4 until the degradation of organic pollutants reaches the expected level. Step S6: When the degradation reaches the expected level, switch the first three-way valve (9) and the second three-way valve (10) to guide the reaction liquid to the piezoelectric particle separator (11) to separate and recover the piezoelectric catalytic particles (24). The separated treatment liquid (16) is discharged from the system through the drain outlet of the wastewater tank (2).

7. The method for treating organic wastewater according to claim 6, characterized in that, The piezoelectric catalytic particles (24) are mixed in organic wastewater (1) at a concentration of 0.2 to 1 g / L; the discharge voltage of the low-temperature plasma generator (19) is 7 to 10 kV.

8. The method for treating organic wastewater according to claim 7, characterized in that, The piezoelectric catalytic particles (24) are magnetic Fe3O4-BaTiO3 composite materials.

9. The method for treating organic wastewater according to claim 8, characterized in that, The Fe3O4-BaTiO3 piezoelectric catalytic particles were synthesized via a one-step hydrothermal method, with a particle magnetization of 50-100 emu / g. The specific steps are as follows: 0.86 mmol Ba(OH)2·8H2O, 0.01 mol KOH, and 0.03 g of Fe3O4 particles with a particle size of 50 nm were added to 60 mL of a 1:1 mixture of n-butanol and deionized water. Then, 0.3 mL of tetrabutyl titanate was added dropwise and the mixture was stirred for 30 minutes. The mixture was then transferred to a hydrothermal reactor and reacted at 180 °C for 10 hours. After the reaction was completed, the mixture was cooled, and the resulting solid product was repeatedly washed with ethanol and deionized water. The product was then vacuum dried at room temperature to obtain Fe3O4-BaTiO3 magnetic piezoelectric catalytic particles.

10. The method for treating organic wastewater according to claim 6, characterized in that, In steps S1 to S4, the pressure pulsation generated by the operation of the Venturi tube hydraulic cavitation device (5), the pressure of which is greater than 1 kPa and the frequency of which is 10 Hz to 500 Hz, is used to drive the piezoelectric catalytic particles (24) to generate a piezoelectric effect.

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