A sewage treatment device based on micro-nano bubbles

Abstract

The application discloses a sewage treatment device based on micro-nano bubbles and relates to the technical field of organic wastewater treatment. The device is sequentially connected by a water inlet power module, a gas-liquid mixing cavity, a multi-stage micro-nano bubble generator and a reaction tank body. The multi-stage micro-nano bubble generator is internally provided with a rotating shearing assembly and a stationary crushing assembly. A hydrophobic passivation layer is arranged on the surface of the shearing blade. The hydrophobic passivation layer is matched with a shell ultrasonic vibrator to realize anti-adhesion and online cleaning. A ring resistance plate and a conical micropore are provided with a hydrophilic layer to improve mass transfer and prevent blockage. The reaction tank body is internally provided with a baffle, an ultraviolet light source and a bottom flow guide sludge discharge structure. The baffle is provided with a silver-doped TiO2 photocatalytic coating doped with nano CeO2, which forms a synergistic degradation with micro-nano bubble ozone oxidation. Through the synergistic effect of the four modules and multiple coatings, photocatalysis and the like, the application effectively solves the problems of difficult degradation, easy adhesion and easy blockage of organic matters in the treatment of high-salt phenol-containing wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically a wastewater treatment device based on micro-nano bubbles. Background Technology

[0002] In the field of industrial wastewater treatment, high-salt phenol-containing organic wastewater generated during the production of phenolic intermediates, synthetic resins, and chemical auxiliaries in the fine chemical industry mainly contains recalcitrant organic compounds such as phenol, phenolic homologues, and aromatic intermediates, as well as soluble inorganic salts such as sodium chloride and sodium sulfate, and commonly contains small amounts of colloids, resin fragments, and emulsified oil. This type of wastewater typically has a COD concentration of 3000–6000 mg / L and a salt content of 2%–5%. The high-salt environment significantly inhibits the oxidative degradation of organic matter, making it even more difficult to remove recalcitrant substances such as phenols, resulting in strong biotoxicity and poor biodegradability (B / C < 0.2).

[0003] Aeration is a crucial step in the biochemical treatment of this type of wastewater and can also play an auxiliary role in physicochemical pretreatment. Oxygen mass transfer efficiency directly determines the removal effect of organic pollutants within the reactor. However, aeration treatment of high-salt phenolic wastewater still presents several technical challenges: High salinity alters the gas-liquid interface characteristics, causing bubbles to coalesce and enlarge, significantly reducing the gas-liquid contact area and drastically lowering the organic matter degradation efficiency; phenols readily polymerize under oxidizing conditions, adhering to the surface of aeration micropores along with colloids, resin fragments, and emulsified oils, further clogging equipment in high-salt environments and severely impacting long-term stable operation; the complex composition and high pollutant concentration of the wastewater hinder fluid flow and mass diffusion, easily leading to uneven local oxygen distribution within the reactor; furthermore, the toxicity of phenols and the high salinity environment inhibit microbial activity, further exacerbating the difficulty of organic matter degradation. Conventional aeration-biochemical combined processes struggle to achieve stable operation due to problems such as high salinity inhibiting microbial activity, easy bubble coalescence, and equipment clogging.

[0004] Patent CN120736705B discloses an aeration tank for wastewater treatment. It reduces the risk of aeration head clogging by cleaning anti-clogging components and expands the aeration range using a horizontal reciprocating movement mechanism, improving oxygenation in conventional wastewater scenarios. However, this device uses conventional aeration methods, which cannot effectively alleviate problems such as bubble coalescence and impaired gas-liquid mass transfer in high-salt environments. It also exhibits poor removal of recalcitrant organic matter such as phenols and has limited effectiveness in improving bubble coalescence and surface adhesion issues of aeration components.

[0005] Patent CN119349783B discloses an urban wastewater treatment device that uses a drive mechanism to reciprocate and rotate an air injection pipe, resulting in a more uniform oxygen distribution within the tank. Designed for urban wastewater, this device produces large-diameter bubbles with rapid ascent, resulting in short contact time with pollutants and low oxygen utilization. In high-salt environments, gas-liquid mass transfer and organic matter degradation are further inhibited. When applied to complex, high-salt organic wastewater containing toxic phenols, the removal efficiency of recalcitrant substances like phenols is low, and the device is prone to clogging, making it difficult to meet the treatment requirements of high-salt, phenol-containing wastewater from fine chemical industries.

[0006] Based on this, it is of great significance to develop a micro-nano bubble wastewater treatment device that does not require pre-desalination, can operate stably directly in high-salt environments, can efficiently generate high specific surface area micro-nano bubbles, ensure gas-liquid mass transfer efficiency in high-salt systems, alleviate component adhesion and clogging, and enhance the removal of refractory organic matter such as phenols. Summary of the Invention

[0007] This invention addresses the problems of existing high-salinity wastewater treatment methods, which rely on pre-desalination, are complex, costly, and unstable. By combining four major components with multiple coatings, ultrasonic cleaning, and photocatalytic antifouling, it achieves direct degradation of organic matter in high-salinity environments. It can efficiently remove COD, total phenols, and SS without pre-desalination, effectively alleviate the inhibitory effect of high salinity on gas-liquid mass transfer and oxidative degradation, and solve the problems of easy adhesion and clogging of equipment.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A wastewater treatment device based on micro-nano bubbles includes an influent power module, a gas-liquid mixing chamber, a multi-stage micro-nano bubble generator, and a reaction tank connected in sequence.

[0010] The water intake power module includes a high-pressure multistage pump and a Venturi jet, and the air intake of the Venturi jet is connected to an ozone generator through a pressure reducing and stabilizing valve.

[0011] The multi-stage micro / nano bubble generator includes a cylindrical shell, inside which a rotating shearing component and a static crushing component are alternately arranged along the axial direction;

[0012] The rotary shearing assembly includes a central rotating shaft and shearing blades fixed on the central rotating shaft. The surface of the shearing blades is provided with a hydrophobic passivation layer. Multiple sets of ultrasonic transducers are arranged along the axial direction on the inner wall of the cylindrical shell.

[0013] The hydrophobic passivation layer material comprises the following components in parts by weight:

[0014] 50-60 parts of KH-560 modified PTFE emulsion, 20-25 parts of citric acid modified nano aluminum titanate, 8-10 parts of PEGDGE modified KH-550, 10-15 parts of anhydrous ethanol, and 2-3 parts of polyaspartic acid ester curing agent.

[0015] The static crushing component includes an annular baffle plate, each annular baffle plate having multiple conical micropores. The surface of the annular baffle plate is provided with a first Al2O3 hydrophilic layer, and the inner wall of the conical micropores is provided with a second Al2O3 hydrophilic layer.

[0016] The reaction tank is equipped with inclined baffles arranged alternately, and the surface of the baffles is coated with a photocatalytic coating; the bottom of the reaction tank is equipped with an inclined guide plate, and the surface of the guide plate is coated with a hydrophilic metal oxide layer; the reaction tank is equipped with an ultraviolet light source.

[0017] The photocatalytic coating is a silver-doped TiO2 photocatalytic coating doped with nano-CeO2.

[0018] In this scheme, the influent power module pressurizes the high-salt phenol-containing wastewater to be treated, and then draws in ozone through a Venturi jet to form a uniform gas-liquid mixture system with the wastewater, laying the foundation for the subsequent generation of micro-nano bubbles.

[0019] The gas-liquid mixing chamber initially mixes the gas-liquid mixture, reducing bubble aggregation and preparing for subsequent multi-stage shearing and crushing.

[0020] In the multi-stage micro / nano bubble generator, micro / nano bubbles are generated through the synergistic effect of a rotating shearing component and a stationary breaking component: the high-speed rotation of the shearing blades generates high-frequency shearing force, forming an extremely high shear rate at the gas-liquid interface, cutting large bubbles into microbubbles with smaller diameters, completing the first-stage shear breaking; subsequently, the gas-liquid mixture enters the stationary breaking component, passing through a conical micro-hole with a specific cone angle on an annular baffle plate. As the fluid passes through the conical micro-hole, the flow velocity increases dramatically and the local pressure drops sharply, instantly inducing a cavitation effect, assisting in bubble breaking, and ultimately generating micro / nano bubbles.

[0021] In practical implementation, phenolic substances in high-salt phenolic wastewater are prone to polymerization during aeration oxidation and shearing crushing. The generated phenolic polymer products, after combining with colloids, easily adhere to the surface of the shear blades, clogging the conical micropores and affecting the stable generation of micro- and nano-bubbles. Based on this, a hydrophobic passivation layer is set on the surface of the shear blades. In this layer, KH-560 modified PTFE emulsion provides hydrophobicity and bubble desorption function for the coating. KH-560 modification can improve the compatibility of PTFE and inorganic fillers, ensuring the uniformity and stability of the coating. Citric acid modified nano-aluminum titanate is used to improve the wear resistance and structural stability of the coating. Citric acid modification can reduce the surface polarity of the powder, improve dispersibility, and increase the density of the coating. PEGDGE modified KH-550 is used to enhance the adhesion strength between the coating and the substrate. PEGDGE modification can optimize the compatibility of the coupling agent and the resin system and improve the interfacial bonding effect. Anhydrous ethanol is used to uniformly disperse the components. Polyaspartic acid ester curing agent is used to form a stable cross-linked structure and improve the high salt resistance of the coating. The final coating is hydrophobic, wear-resistant, highly adhesive, resistant to high salt, and has surface passivation and anti-adhesion functions. It can enable bubbles to quickly detach from the blade surface and prevent bubble merging, thus ensuring the shearing and breaking effect. At the same time, the surface passivation inhibits the adhesion of phenolic polymerization products and colloids to the blade surface. Combined with the ultrasonic transducer on the inner wall of the cylindrical shell, it can achieve online self-cleaning and maintain shearing efficiency.

[0022] Hydrophilic layers are applied to the surfaces of the annular baffle plate and the conical micropores. The hydrophilic metal oxide layer on the annular baffle plate enhances the affinity between the plate surface and the aqueous phase, allowing the newly formed surface generated by cavitation to be quickly wetted by water molecules. This reduces collisions between micro and nano bubbles, prolongs their residence time in wastewater, and improves gas-liquid mass transfer efficiency. Simultaneously, it reduces the adhesion of phenolic polymerization products and colloids, preventing micropore blockage and ensuring effective bubble generation. This device reduces bubble adhesion through a hydrophobic coating on the shear blade surface, promoting rapid bubble detachment and reducing adhesion and aggregation. Combined with the hydrophilic layer on the inner wall of the annular baffle plate and the conical micropores, it stabilizes the gas-liquid interface and reduces the probability of micro and nano bubble collisions and mergers. The synergistic effect of these two layers effectively solves the problem of altered gas-liquid interface characteristics in high-salt environments, which leads to bubble aggregation and enlargement, and a decrease in mass transfer area.

[0023] In the reaction tank, baffles alter the water flow path, prolonging wastewater retention time and increasing the contact time and area between micro- and nano-bubbles and recalcitrant organic matter, thus laying the foundation for efficient degradation. Under ultraviolet light irradiation, the silver-doped TiO2 photocatalytic coating on the baffle surface forms a synergistic degradation effect with the micro- and nano-bubbles, efficiently degrading phenolic substances and other recalcitrant organic matter in the wastewater and enhancing the wastewater treatment effect. In practical implementation, phenolic substances are first oxidized into intermediate products during photocatalytic degradation. These intermediate products easily polymerize to form large, inert molecules that coat the surface of the silver-doped TiO2 photocatalytic coating, leading to decreased catalytic activity. Simultaneously, the high-salt environment accelerates colloidal coagulation, further exacerbating sediment buildup at the bottom of the pool. Therefore, doping the silver-doped TiO2 photocatalytic coating with nano-CeO2 increases the oxygen vacancy concentration, delays the adsorption and coverage of intermediate products, maintains catalytic activity, enhances the coating's anti-fouling ability, and promotes its continuous degradation effect. Furthermore, to address the sediment buildup problem at the bottom of the pool, an inclined guide plate is installed to guide the settled colloids and salt sludge towards the discharge outlet, facilitating regular discharge and preventing the formation of localized dead zones. The guide plate surface is coated with a hydrophilic metal oxide layer, which enhances the affinity between the guide plate and the aqueous phase, reducing the adhesion and deposition of colloids and salt sludge on the guide plate surface, lowering the friction between them and the guide plate, and further assisting in guiding the sediment towards the discharge outlet for regular discharge.

[0024] In summary, the device provided by this invention, through the synergistic effect of the water inlet power module, the gas-liquid mixing chamber, the multi-stage micro-nano bubble generator, and the reaction tank, can effectively solve the problems of low removal efficiency of refractory organic matter such as phenols, easy bubble merging, and easy adhesion and blockage of components in high-salt environments, and achieves efficient degradation of organic matter and long-term stable operation of the device without desalination.

[0025] Preferably, the photocatalytic coating is prepared by mixing silver-doped TiO2 photocatalytic powder and nano CeO2 at a mass ratio of 95:(1~5), then adding a binder, stirring evenly, spraying it onto the surface of the baffle plate, and baking to cure it.

[0026] Preferably, in the multi-stage micro / nano bubble generator, the number of rotating shear components and static crushing components are 3 to 5, and the axial distance between two adjacent components is 10 to 20 mm; the frequency of the ultrasonic transducer is 40 to 60 kHz, and the power density is 0.3 to 0.5 W / cm².

[0027] Preferably, the intake ratio of the Venturi jet is 1:(5~10); and the outlet pressure of the high-pressure multistage pump is 1.5~3.0MPa.

[0028] Preferably, the vertical distance between two adjacent baffles in the reaction tank is 150~300mm, the angle between the baffle and the tank wall is 30~60°, and the angle between the inclined guide plate and the bottom of the tank is 15~20°.

[0029] This solution optimizes the flow field distribution inside the reaction tank by limiting the spacing of the baffles, the angle between them and the tank wall, and the angle between the inclined guide plate and the tank bottom. This allows the water flow to form a stable S-shaped path, effectively extending the residence time of wastewater in the tank and increasing the contact time and area between micro-nano bubbles and recalcitrant organic compounds such as phenols. This creates sufficient conditions for the synergistic degradation of photocatalytic coatings and micro-nano bubbles.

[0030] Preferably, the bottom of the inclined guide plate is also provided with an ultrasonic wave generating array, the frequency of which is 20~40kHz and the power density is 0.1~0.3W / cm².

[0031] This solution utilizes an ultrasonic wave generator array to work synergistically with a flow deflector. The array generates moderate vibrations, which slow down the settling of colloids and small amounts of salt mud in a high-salt environment, preventing rapid accumulation of sediment that could cover the array and cause it to lose its agitation function. Simultaneously, the vibrations create fluid disturbances that help loosen the settled sediment. By limiting the angle between the flow deflector and the pool bottom, and by coating the surface with a hydrophilic metal oxide layer, the adhesion of colloids and salt mud is reduced, decreasing the friction between the sediment and the flow deflector. This guides the sediment, loosened by the ultrasonic waves, towards the discharge outlet, thus preventing the formation of localized dead zones at the pool bottom.

[0032] Preferably, the inlet diameter of the conical micropore is 0.5~1mm and the outlet diameter is 0.012~0.05mm, exhibiting a gradient contraction structure.

[0033] This solution, by limiting the structure of the conical micropores and the inlet and outlet diameter parameters, can ensure that the fluid velocity increases sharply and the pressure drops suddenly when it passes through, thus successfully inducing the cavitation effect, realizing the secondary breakup of microbubbles, and ensuring the generation effect and stability of micro-nano bubbles.

[0034] Preferably, the inner wall of the reaction tank and the surface of the baffle plate are coated with an anti-corrosion coating; the hydrophilic metal oxide is selected from Al2O3 and TiO2; the anti-corrosion coating is selected from fluorocarbon resin coating and special epoxy resin layer.

[0035] This solution effectively resists the strong corrosive effects of high-salt phenol-containing wastewater by coating the inner wall of the reaction tank and the surface of the baffles with an anti-corrosion coating, and by specifying the specific type of anti-corrosion coating, thus preventing damage to the tank and baffles and extending the service life of the device. By specifying the specific type of hydrophilic metal oxide, the affinity between the surface of the annular baffle and the inclined guide plate and the aqueous phase can be enhanced, reducing the adhesion and deposition of colloids and salt mud, and helping to improve the guiding and anti-clogging effects. Moreover, the material is stable and does not affect the wastewater treatment effect, ensuring the continuous functioning of each component.

[0036] Preferably, the thickness of the hydrophobic passivation layer is 1~3μm; the thickness of the first Al2O3 hydrophilic layer is 30~50μm; and the thickness of the second Al2O3 hydrophilic layer is 1~2μm.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] In existing technologies, the treatment of high-salt phenol-containing wastewater requires a pre-desalination process, which suffers from problems such as complex processes, high operating costs, easy equipment clogging, and low degradation efficiency of organic matter under high salinity. This application utilizes four major components—an influent power module, a gas-liquid mixing chamber, a multi-stage micro / nano bubble generator, and a reaction tank—worked synergistically with a hydrophobic passivation coating, a hydrophilic anti-clogging structure, ultrasonic online cleaning, and a photocatalytic antifouling coating. This allows for the direct and efficient degradation of recalcitrant organic matter in a high-salt environment without pre-desalination. The effluent COD is ≤322 mg / L, total phenols ≤0.48 mg / L, SS ≤14 mg / L, and Cu... 2+ With Zn 2+ All concentrations are ≤0.09 mg / L, demonstrating excellent pollutant removal efficiency. Simultaneously, it can significantly inhibit the adhesion of phenolic polymers and colloids. The system blockage frequency is ≤1 time after a cumulative 72 hours of operation. The average coverage area of ​​shear blade deposits is ≤7.8%, and the average thickness at the thickest point is ≤19 μm. The device operates stably and has excellent anti-clogging and anti-fouling capabilities, enabling long-term efficient and stable treatment of high-salt phenolic organic wastewater. Attached Figure Description

[0039] Figure 1 : A cross-sectional view of a multi-stage micro / nano bubble generator from the front view;

[0040] Figure 2 : Figure 1 A schematic diagram of the structure of the central annular baffle plate from a top view.

[0041] Figure 3 : A schematic cross-sectional view of the reaction tank from the front view;

[0042] In the figure, 101-cylindrical shell, 102-central rotating shaft, 103-shear blade, 104-annular baffle, 105-conical micropore, 201-baffle plate, 202-guide plate, 203-ultraviolet light source, 204-ultrasonic array. Detailed Implementation

[0043] Example 1

[0044] This embodiment provides a wastewater treatment device based on micro-nano bubbles. The overall device consists of four main parts: an inlet power module, a gas-liquid mixing chamber, a multi-stage micro-nano bubble generator, and a reaction tank. The parts are sequentially connected by 316L stainless steel pressure-resistant pipes. The pipe interfaces are sealed with flanges and fluororubber sealing rings. The overall system can stably withstand a working pressure of 1.5~3.0MPa and there is no gas-liquid leakage during operation.

[0045] The inlet power module mainly consists of a high-pressure multistage pump and a Venturi jet injector. The high-pressure multistage pump provides the fluid transport power for the system, and the air intake of the Venturi jet injector is connected to an ozone generator through a pressure reducing and stabilizing valve, which can stably draw ozone into the gas-liquid mixture system. In this embodiment, the outlet pressure of the high-pressure multistage pump is set to 1.5 MPa, the air intake ratio of the Venturi jet injector is 1:5, and the volume ratio of ozone to wastewater is 1:15, achieving efficient premixing of ozone and wastewater. The ozone generator uses an oxygen source, and the ozone gas phase mass concentration is 65 mg / L.

[0046] like Figure 1 As shown, the gas-liquid mixing chamber is a cylindrical pressure-resistant cavity with an effective volume of 0.5 m³. The inner wall is lined with a fluorocarbon anti-corrosion coating. An internal static mixing component, an SK-type static mixer made of 316L stainless steel, is installed inside. Multiple sets of staggered blades achieve non-powered homogenization of the gas-liquid mixture, with a blade spacing of 20 mm. The gas-liquid mixture from the water inlet power module is homogenized non-powered by the static mixing component, reducing bubble agglomeration and providing a stable feed for the subsequent multi-stage micro / nano bubble generator's fine crushing process.

[0047] like Figure 1As shown, the multi-stage micro / nano bubble generator has a cylindrical shell 101 with an inner diameter of 200 mm and an axial length of 1200 mm. Rotary shearing components and stationary crushing components are alternately arranged axially inside the shell, with four sets of rotary shearing components and four sets of stationary crushing components, and an axial spacing of 10 mm between adjacent components. The outer wall of the annular baffle 104 of each set of stationary crushing components is sealed and fixedly connected to the inner wall of the cylindrical shell 101. Four sets of ultrasonic transducers are arranged axially on the inner wall of the cylindrical shell 101, corresponding to the middle section between each set of rotary shearing components and stationary crushing components. Each set contains two fully sealed waterproof transducer units, symmetrically installed on both sides of the inner wall of the shell, enabling long-term stable operation underwater. Each ultrasonic transducer has a frequency of 40 kHz and a power density of 0.3 W / cm², achieving online ultrasonic cleaning during operation to prevent the adhesion of phenolic polymers and colloids.

[0048] The rotary shear assembly includes a central shaft 102 and shear blades 103. The central shaft 102 is coaxially driven by a drive motor mounted on the top of the cylindrical housing 101. A single motor (1.5kW power, 3500r / min during operation) drives the entire rotary shear assembly. The central shaft 102 and the annular baffle plate 104 are fitted with a sealed clearance. The central shaft 102 passes through the central mounting hole of the annular baffle plate from top to bottom. A labyrinth seal structure is installed inside the mounting hole, with the sealing clearance controlled between 0.05 and 0.1 mm. The bottom end of the central shaft 102 forms a rotational support connection with a fixed support inside the housing, ensuring coaxiality and structural stability during high-speed rotation. Each rotary shear assembly has four shear blades 103 evenly distributed coaxially around the central shaft 102 at the same radial height. The blades are made of titanium alloy and are 80 mm long. A hydrophobic passivation layer is provided on the surface of the blades.

[0049] like Figure 2 As shown, the static crushing assembly includes an annular baffle plate 104, which is sealed and fixed to the inner wall of the shell. The plate is 0.8 mm thick (processed by femtosecond laser) and has multiple conical micropores 105 evenly distributed on its surface. The conical micropores have a gradient contraction structure with an inlet diameter of 0.5 mm and an outlet diameter of 12 μm. The upper and lower surfaces of the annular baffle plate 104 are completely covered with a first Al2O3 hydrophilic layer, and the entire inner wall of the conical micropores 105 is covered with a second Al2O3 hydrophilic layer.

[0050] like Figure 3As shown, the reaction tank has a rectangular structure with dimensions of 2m long × 1m wide × 1.5m high. A cover plate is installed at the top of the tank to prevent debris from falling in and water vapor from escaping. The water inlet of the reaction tank is located on the upper part of the side wall of the tank, above the starting end of the first baffle plate, and is connected to the outlet pipe of the multi-stage micro / nano bubble generator. Inside the tank, there are four alternately arranged inclined baffle plates 201. The baffle plates form a 30° angle with the tank wall, and the vertical spacing between adjacent baffle plates is 150mm. Adjacent baffle plates have a 1 / 3 overlap in the vertical direction, ensuring that the water flow forms a stable S-shaped channel without short-circuiting. Three sides of the baffle plates are fixedly connected to the inner wall of the tank, with only the downward-sloping end being a free end, forcibly forming an S-shaped channel. The upper and lower surfaces of all baffle plates 201 are completely coated with a silver-doped TiO2 photocatalytic coating doped with nano-CeO2, ensuring catalytic activity in the ultraviolet irradiation area.

[0051] The bottom of the reaction tank is equipped with a guide plate 202, which is at a 15° angle to the bottom of the tank. The bottom wall of the reaction tank and the inclined guide plate are set in a synchronous inclination. The guide plate adopts a single-sided fixed structure: only the high end is fixedly connected to the tank wall, and the low end faces the sewage outlet. Both sides of the guide plate adjacent to the fixed end are reserved with a 5-10mm assembly gap between themselves and the tank wall, so as not to contact the tank wall, ensuring that the sludge can pass through smoothly and flow to the sewage outlet. The surface of the guide plate is coated with an Al2O3 hydrophilic metal oxide layer to guide the colloid and salt sludge to flow to the sewage outlet.

[0052] like Figure 3 As shown, the UV light source 203 is fully waterproof and is vertically installed on both sides of the reaction tank. It is arranged above the uppermost baffle, in the gap between adjacent alternating baffles, and below the lowermost baffle, arranged sequentially from top to bottom to ensure that the top surface of the uppermost baffle and the light-facing surfaces of all baffles are evenly illuminated. Each lamp has a power of 20W, a center wavelength of 254nm, and a radiation intensity of ≥100μW / cm². The outer shell is fully sealed and waterproof, and it can be used for a long time in high humidity environments.

[0053] like Figure 3 As shown, an ultrasonic wave generator array 204 is installed at the bottom of the reaction tank. The ultrasonic wave generator array 204 is evenly arranged in a rectangular matrix across the entire bottom area of ​​the inclined guide plate, fully covering the sedimentation surface of the tank bottom. All transducers are installed using an embedded waterproof seal. Because the distance between the guide plate 202 and the tank bottom is relatively close, the vibration waves can penetrate the water and act on the sludge deposited at the bottom of the tank, achieving loosening and fluidization of the sludge clumps. Compared to being located at the bottom of the tank, it is less likely to be covered by sludge accumulation; during operation, only the vibrating end generates high-frequency vibration, and the guide plate 202 itself does not vibrate as a whole. The vibration waves can cover the entire sedimentation area at the bottom of the tank, achieving sludge loosening and sludge clump breaking. Combined with the inclined guiding action of the guide plate 202, the sludge is smoothly guided to the discharge outlet, ensuring the long-term stable operation of the ultrasonic unit.

[0054] The sewage outlet is located at the lowest point of the tank bottom, and the drainage outlet of the reaction tank is located 5cm above the sewage outlet. A 50μm 316L stainless steel removable filter screen is installed inside the drainage outlet to intercept fine impurities and prevent them from being discharged with the clean water.

[0055] The preparation methods of each functional powder and coating in this embodiment are as follows:

[0056] Hydrophobic passivation layer for shear blades: Take 50 parts by weight of KH-560 modified PTFE emulsion, 20 parts by weight of citric acid modified nano aluminum titanate, 10 parts by weight of PEGDGE modified KH-550, and 15 parts by weight of anhydrous ethanol, mix them, stir at 300 r / min for 30 min until uniform, add 3 parts by weight of polyaspartic acid ester curing agent (polyaspartic acid ester polyurea curing agent), continue stirring for 15 min until the system is uniform, apply it to the surface of the shear blade by spraying, cure at 80℃ for 2 h, then heat to 120℃ for 1 h, cool and form, with a thickness of 2 μm.

[0057] The preparation method of KH-560 modified PTFE emulsion is as follows: the solid content of PTFE emulsion is adjusted to 30%, KH-560 silane coupling agent is added at 2% of the mass of PTFE solid material, stirred at 300 r / min for 30 min, reacted at 50℃ for 2 h, and KH-560 modified PTFE emulsion is obtained after cooling.

[0058] The preparation method of citric acid modified nano aluminum titanate is as follows: nano aluminum titanate is dispersed in anhydrous ethanol with a mass concentration of 10%, and citric acid is added at 3% of the mass of nano aluminum titanate. The mixture is stirred at 300 r / min for 60 min, reacted at 60℃ for 3 h, centrifuged, washed, and dried at 80℃ to obtain citric acid modified nano aluminum titanate.

[0059] The preparation method of PEGDGE modified KH-550 is as follows: KH-550 and anhydrous ethanol are mixed at a mass ratio of 1:9. PEGDGE with a number average molecular weight of 400 and an epoxy value of 0.60~0.70 eq / 100g is measured at 10% of the mass of KH-550 and slowly added dropwise to the system under a water bath at 40~45℃. After the addition is complete, the mixture is stirred for 60 min. The reaction endpoint is defined as the epoxy value of the system dropping below 0.06 eq / 100g and the solution becoming homogeneous, transparent, and gel-free, thus obtaining the PEGDGE modified KH-550 ethanol solution.

[0060] Hydrophilic coating of annular baffle: The first Al2O3 hydrophilic layer is plasma sprayed with a thickness of 30μm; the second Al2O3 hydrophilic layer is atomic layer deposition to coat the inner wall of the conical micropores with a thickness of 1μm; both coatings are cured at 200℃ for 60min.

[0061] Baffle photocatalytic coating:

[0062] ① Add tetrabutyl titanate and silver nitrate to anhydrous ethanol at a molar ratio of 97:3, stir for 30 min until completely dissolved, slowly add deionized water for hydrolysis, adjust the pH to 4.0 with dilute nitric acid, and continue stirring for 60 min to form a sol; dry at 105℃ and calcine at 500℃ for 2 h, cool naturally and grind through a 200 mesh sieve to obtain silver-doped TiO2 photocatalytic powder.

[0063] ② Mix silver-doped TiO2 photocatalytic powder and nano CeO2 at a mass ratio of 95:1, add 10% organosilicon binder by mass, stir at 400 r / min for 40 min, and then spray evenly onto the entire surface of the baffle plate. Bake at 150℃ for 40 min to form the shape.

[0064] Working principle of Example 1:

[0065] All wastewater treated in the embodiments and comparative examples of this application is from the same batch of wastewater produced in the fine chemical industry. Specifically, it originates from high-salt, phenol-containing organic wastewater generated during the production of phenolic intermediates, synthetic resins, and chemical auxiliaries in the fine chemical industry. The specific indicators are as follows:

[0066] COD (Chemical Oxygen Demand) was 4201 mg / L, BOD (Biochemical Oxygen Demand) was 380 mg / L, phenolic compounds were 65 mg / L, suspended particulate matter (SS) was 120 mg / L, and Cu... 2+ Concentration of 3 mg / L, Zn 2+ The concentration was 2 mg / L, the content of high-salt components (calculated as NaCl) was 5000 mg / L, the pH value of the wastewater was 7.0, and the water temperature was 25℃.

[0067] The specific processing procedure and working principle are as follows:

[0068] First, the wastewater to be treated is transported to the gas-liquid mixing stage via the inlet power module (high-pressure multistage pump). The Venturi jet in the inlet power module draws in ozone generated by the ozone generator, which is then fully pre-mixed with the wastewater to form an ozone-containing gas-liquid mixture. At this stage, the ozone initially reacts with phenolic substances and easily degradable organic pollutants in the wastewater through oxidation, achieving preliminary purification. Subsequently, the gas-liquid mixture enters the gas-liquid mixing chamber, where it is further homogenized by internal static mixing components to prevent bubble aggregation and provide stable feeding conditions for the subsequent generation of micro-nano bubbles.

[0069] The homogenized gas-liquid mixture enters a multi-stage micro / nano bubble generator. Driven by the central shaft 102, the shear blades 103 of the rotating shear assembly rotate at high speed. Combined with the blocking effect of the annular baffle 104, the bubbles in the gas-liquid mixture are sheared and broken into micro / nano scale particles. Simultaneously, the ultrasonic transducer continuously operates, cleaning the blades and micropore surfaces online to prevent phenolic polymers, colloids, and suspended particles from adhering and clogging, ensuring stable generation of micro / nano bubbles. The generated micro / nano bubbles carry ozone, which comes into full contact with the wastewater, significantly improving the ozone mass transfer efficiency and enhancing the oxidative decomposition of recalcitrant organic pollutants (polycyclic aromatic hydrocarbons and halogenated hydrocarbons), while effectively removing phenolic substances from the wastewater.

[0070] After undergoing micro-nano bubble oxidation treatment, the wastewater enters the reaction tank and flows slowly along the S-shaped flow channel formed by the baffle plate 201, extending the residence time of the wastewater in the tank. Ultraviolet light sources 203 on both sides of the tank continuously irradiate the wastewater, exciting the silver-doped TiO2 photocatalytic coating (containing nano-CeO2) on the surface of the baffle plate 201 to generate photogenerated charge carriers. These carriers synergize with residual ozone to further oxidize and decompose undegraded organic pollutants in the wastewater, reducing its toxicity. During this process, the guide plate 202 guides the wastewater towards the discharge outlet, and the vibration waves generated by the bottom ultrasonic array 204 loosen the sludge deposited at the bottom of the tank, preventing sludge accumulation and guiding the broken sludge to the discharge outlet. After the wastewater stays in the tank for 50 minutes (the residence time is calculated from the time the wastewater completely enters the reaction tank), it is discharged and collected through the drain outlet. During the discharge process, a stainless steel filter screen inside the drain outlet intercepts fine impurities.

[0071] Example 2

[0072] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0073] 1. The outlet pressure of the high-pressure multistage pump is adjusted to 2.0 MPa, and the air intake ratio of the Venturi ejector is adjusted to 1:8;

[0074] 2. Adjust the axial spacing between adjacent components to 15 mm;

[0075] 3. The ultrasonic transducer frequency was adjusted to 50 kHz, and the power density was adjusted to 0.4 W / cm²;

[0076] 4. The inlet diameter of the conical micro-orifice 105 is adjusted to 0.7 mm, and the outlet diameter is adjusted to 20 μm;

[0077] Example 3

[0078] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0079] 1. The outlet pressure of the high-pressure multistage pump is adjusted to 3.0 MPa, and the air intake ratio of the Venturi ejector is adjusted to 1:10;

[0080] 2. The ultrasonic transducer frequency was adjusted to 60 kHz, and the power density was adjusted to 0.5 W / cm²;

[0081] 3. The inlet diameter of the conical micro-orifice 105 is adjusted to 1.0 mm, and the outlet diameter is adjusted to 50 μm.

[0082] Example 4

[0083] Compared to Example 1, only the following coating thickness parameters have been modified; all other aspects are the same as in Example 1:

[0084] 1. The hydrophobic passivation coating of the shear blade is 1 μm thick;

[0085] 2. The thickness of the first Al2O3 hydrophilic layer of the annular baffle plate 104 is adjusted to 50 μm.

[0086] 3. The second Al2O3 hydrophilic layer is coated with atomic layer deposition to cover the inner wall of the conical micropores, with a thickness of 2μm.

[0087] Example 5

[0088] Compared to Example 1, only the following coating parameters have been modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0089] Hydrophobic passivation layer for shear blades: Take 60 parts by weight of KH-560 modified PTFE emulsion, 25 parts by weight of citric acid modified nano aluminum titanate, 8 parts by weight of PEGDGE modified KH-550, and 15 parts by weight of anhydrous ethanol, mix them, stir at 300 r / min for 30 min until uniform, add 2 parts by weight of polyaspartic acid ester curing agent, continue stirring for 15 min until the system is uniform, apply it to the surface of the shear blade by spraying, cure at 80℃ for 2 h, then heat to 120℃ for 1 h, cool and form, with a thickness of 3 μm.

[0090] Comparative Example 1

[0091] The hydrophobic passivation layer on the shear blade surface was prepared using unmodified conventional raw materials: 50 parts of ordinary PTFE emulsion, 20 parts of ordinary nano aluminum titanate, 10 parts of unmodified KH-550, and 15 parts of anhydrous ethanol were mixed and stirred at 300 r / min for 30 min until uniform. 3 parts of polyaspartic acid ester curing agent were added and stirred for another 15 min until the system was homogeneous. After spraying, the mixture was cured at 80℃ for 2 h, then heated to 120℃ for 1 h, cooled and shaped, with a thickness of 2 μm.

[0092] Comparative Example 2

[0093] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0094] In the hydrophobic passivation layer on the shear blade surface, citric acid-modified nano aluminum titanate was replaced with ordinary nano Al2O3, with the amount remaining at 20 parts.

[0095] Comparative Example 3

[0096] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0097] No Al2O3 hydrophilic layer is prepared on the inner wall of the annular flow barrier 104 and the conical micropore 105.

[0098] Comparative Example 4

[0099] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0100] The photocatalytic coating on the surface of baffle 201 does not contain nano CeO2, but only uses silver-doped TiO2.

[0101] Comparative Example 5

[0102] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0103] 1. Remove the bottom guide plate 202 of the reaction tank;

[0104] 2. The ultrasonic wave generator array 204 is directly installed on the bottom of the horizontal pool.

[0105] Comparative Example 6

[0106] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0107] All ultrasonic transducers within the multi-stage micro / nano bubble generator were removed.

[0108] Comparative Example 7

[0109] Compared to Example 1, only the following parameters are modified; all other aspects are the same as in Example 1 unless otherwise mentioned:

[0110] 1. Remove the multi-stage micro-nano bubble generator and eliminate the ozone generator and ozone intake structure;

[0111] 2. Instead of using conventional microporous aerators in the gas-liquid mixing chamber, oxygen is introduced for aeration and mixing.

[0112] 3. The water flow path is: water inlet power module → gas-liquid mixing chamber → reaction tank; conventional oxidation is carried out using oxygen as an oxidant, which only produces ordinary millimeter-sized bubbles, without the enhanced mass transfer effect of micro-nano bubbles and ozone advanced oxidation effect;

[0113] The rest of the structure, components, parameters, and manufacturing process remain unchanged.

[0114] Comparative Example 8

[0115] Compared to Example 1, only the following modifications are made; all other aspects not mentioned are the same as in Example 1:

[0116] In the hydrophobic passivation layer of the shear blade, the KH-560 modified PTFE emulsion was replaced with ordinary unmodified PTFE emulsion, with the amount still being 50 parts.

[0117] Comparative Example 9

[0118] Compared to Example 1, only the following modifications are made; all other aspects not mentioned are the same as in Example 1:

[0119] In the hydrophobic passivation layer of the shear blade, the PEGDGE modified KH-550 was replaced with ordinary unmodified KH-550, and the amount was still 10 parts.

[0120] Experimental Example

[0121] To verify the treatment efficiency of the micro-nano bubble-based wastewater treatment device of this invention for high-salt, phenol-containing organic wastewater from fine chemical industries, experiments were conducted on Examples 1-5 and Comparative Examples 1-9. All experiments were repeated three times in parallel, with a relative standard deviation (RSD) ≤ 5%. The average value was taken as the final result (as shown in Table 1). Specific detection indicators and methods are as follows:

[0122] (1) Effluent water quality testing:

[0123] ① COD: measured using the dichromate method, unit: mg / L.

[0124] ② BOD5: Measured using the dilution and inoculation method, unit: mg / L.

[0125] ③ Total phenols: determined by bromination titration, unit: mg / L.

[0126] ④ SS (Suspended solids): Measured by gravity, unit: mg / L.

[0127] ⑤ Cu 2+ Zn 2+ Atomic absorption spectrophotometry was used, and the unit is mg / L.

[0128] (2) Equipment operational stability testing:

[0129] System clogging frequency: The number of times the conical micropores of the multi-stage micro-nano bubble generator were cleared after a cumulative 72 hours of operation is recorded, in units of times / 72 hours.

[0130] (3) Detection of sediments from sheared blades:

[0131] The cylindrical shell of the multi-stage micro-nano bubble generator has inspection ports on the side wall corresponding to each group of rotating shearing components. After the device has accumulated 72 hours of operation, it is shut down. Through the inspection ports, an industrial endoscope, combined with micro-thickness measurement and image recognition, is inserted into the interior to inspect all shearing blades.

[0132] ① Average sediment coverage area: The percentage of sediment coverage area for each leaf was measured, and the average coverage area of ​​the 16 leaves was calculated (unit: ).

[0133] ② Average thickness of the thickest part of the sediment: The thickness of the thickest part of the sediment was measured for each leaf, and the average value of the thickest part of the 16 leaves was calculated in μm.

[0134] Table 1:

[0135]

[0136] Note: "-" in Table 1 indicates that the test was not performed.

[0137] As can be seen from Table 1:

[0138] Examples 1-5 demonstrate that even in high-salt environments, the system can efficiently degrade recalcitrant organic compounds such as COD and total phenols, producing excellent effluent quality, low system clogging frequency, and minimal and thin deposit coverage on the shear blade surface. This allows for stable and efficient treatment of high-salt, phenol-containing wastewater without the need for desalination, fully showcasing the technical advantages of this invention in achieving efficient and stable operation under complex conditions of high salt inhibition, easy polymerization of phenols, and easy adhesion and clogging. Specifically, the effluent COD concentration is ≤322 mg / L, and the effluent total phenol concentration is ≤0.48 mg / L, achieving efficient degradation of recalcitrant organic compounds; the effluent SS concentration is ≤14 mg / L, and the heavy metal Cu... 2+ Zn 2+ The effluent concentration is ≤0.09 mg / L, demonstrating excellent pollutant removal efficiency; the system clogging frequency is ≤1 time / 72h, ensuring the stability of continuous operation of the device; the average coverage area of ​​shear blade sediment is ≤7.8%, and the average thickness at the thickest point is ≤19μm, significantly alleviating the problem of phenolic polymer and colloid adhesion and accumulation, and ensuring the stable generation and efficient mass transfer of micro-nano bubbles.

[0139] Comparative Example 1 uses unmodified conventional raw materials, resulting in poor coating dispersibility, compatibility, and salt resistance, making it prone to adhesion and clogging. Comparative Example 2 replaces aluminum titanate with nano-Al2O3, which has high surface polarity, easily adsorbs pollutants, and reduces anti-adhesion and wear resistance. Comparative Example 3, due to the lack of an Al2O3 hydrophilic layer on the annular baffle plate and the inner wall of the conical micropores, fluid flow is impaired, phenolic polymers and colloids easily adhere and clog, significantly reducing treatment efficiency and operational stability. Comparative Example 4, because the photocatalytic coating of the baffle plate does not contain nano-CeO2, it is easily covered and deactivated by intermediate products, resulting in poor organic matter degradation and deteriorating effluent quality. Comparative Example 5, due to the removal of the inclined guide plate and unreasonable ultrasonic generator array arrangement, the flow field and sedimentation state within the tank deteriorate, the removal effect of suspended solids and colloids weakens, and the effluent SS is high. Comparative Example 6: Due to the removal of the ultrasonic transducer within the multi-stage micro / nano bubble generator, the blades and micropores could not be cleaned online, leading to increased sediment adhesion, frequent detachment and blockage, decreased micro / nano bubble generation efficiency, and a significant deterioration in effluent indicators. Comparative Example 7: Using conventional aeration + oxygen oxidation, it lacked the high specific surface area advantage of micro / nano bubbles and the advanced oxidation effect of ozone, resulting in low gas-liquid mass transfer efficiency, ineffective oxidation and decomposition of recalcitrant organic matter, and poor effluent indicators.

[0140] In addition, after the device ran continuously for 72 hours, besides testing the thickness of the hydrophobic passivation layer on the shear blades using a non-destructive thickness gauge, the appearance of the hydrophobic passivation coatings in Examples 1-5, Comparative Examples 1-2, and Comparative Examples 8-9 was also observed, as follows:

[0141] Examples 1-5 show no significant decrease in the thickness of the hydrophobic passivation coating, with a uniform and intact surface, and no wear, peeling, exposure of the substrate, or flaking. Comparative Example 1, due to the use of unmodified conventional raw materials, suffers from poor component compatibility, weak interfacial bonding, and insufficient wear resistance and high-salt resistance, resulting in significant coating thinning and large-area peeling after operation. Comparative Example 2, by replacing aluminum titanate with ordinary nano-Al2O3, exhibits high surface polarity, easily adsorbs contaminants, and has even worse wear resistance, leading to significant coating wear and pinpoint peeling. Comparative Example 8, due to the use of unmodified PTFE emulsion, has poor compatibility with inorganic fillers, making the coating prone to defects and resulting in large-scale peeling under high-salt shear conditions. Comparative Example 9, due to the use of unmodified KH-550, suffers from insufficient adhesion strength between the coating and the substrate, leading to easy edge wear, exposure of the substrate, and a significant decrease in integrity.

[0142] Furthermore, the hydrophobic passivation coatings of Examples 1-5 have an adhesion grade of 1. After being soaked in a 5% NaCl salt solution for 30 days, the coatings showed no peeling, no exposure of the substrate, and no flaking, maintaining good integrity.

Claims

1. A wastewater treatment device based on micro / nano bubbles, characterized in that, It includes a sequentially connected water inlet power module, gas-liquid mixing chamber, multi-stage micro-nano bubble generator, and reaction tank; The water intake power module includes a high-pressure multistage pump and a Venturi jet, and the air intake of the Venturi jet is connected to an ozone generator through a pressure reducing and stabilizing valve. The multi-stage micro-nano bubble generator includes a cylindrical shell (101), and a rotating shearing component and a static crushing component are alternately arranged along the axial direction inside the cylindrical shell (101); The rotary shearing assembly includes a central rotating shaft (102) and shearing blades (103) fixed on the central rotating shaft (102). The surface of the shearing blades (103) is provided with a hydrophobic passivation layer. Multiple sets of ultrasonic transducers are arranged along the axial direction on the inner wall of the cylindrical shell (101). The hydrophobic passivation layer material comprises the following components in parts by weight: 50-60 parts of KH-560 modified PTFE emulsion, 20-25 parts of citric acid modified nano aluminum titanate, 8-10 parts of PEGDGE modified KH-550, 10-15 parts of anhydrous ethanol, and 2-3 parts of polyaspartic acid ester curing agent. The static crushing component includes an annular baffle plate (104), and the annular baffle plate (104) is provided with a plurality of conical micropores (105) on its plate body. The surface of the annular baffle plate (104) is provided with a first Al2O3 hydrophilic layer, and the inner wall of the conical micropores (105) is provided with a second Al2O3 hydrophilic layer. The reaction tank is provided with inclined baffles (201) arranged alternately, and the surface of the baffles (201) is provided with a photocatalytic coating; the bottom of the reaction tank is provided with an inclined guide plate (202), and the surface of the guide plate (202) is provided with a hydrophilic metal oxide layer; the reaction tank is provided with an ultraviolet light source (203). The photocatalytic coating is a silver-doped TiO2 photocatalytic coating doped with nano-CeO2.

2. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The photocatalytic coating is prepared by mixing silver-doped TiO2 photocatalytic powder and nano CeO2 at a mass ratio of 95:(1~5), then adding a binder, stirring evenly, and spraying it onto the surface of the baffle plate (201), and then baking and curing it.

3. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, In the multi-stage micro / nano bubble generator, the number of rotating shear components and static crushing components are 3 to 5, and the axial distance between two adjacent components is 10 to 20 mm; the frequency of the ultrasonic transducer is 40 to 60 kHz, and the power density is 0.3 to 0.5 W / cm².

4. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The intake ratio of the Venturi jet is 1:(5~10); the outlet pressure of the high-pressure multistage pump is 1.5~3.0MPa.

5. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The vertical distance between two adjacent baffles (201) in the reaction tank is 150~300mm, and the angle between the baffle (201) and the tank wall is 30~60°; the angle between the inclined guide plate (202) and the bottom of the tank is 15~20°.

6. The wastewater treatment device based on micro / nano bubbles according to claim 5, characterized in that, The bottom of the inclined guide plate is also provided with an ultrasonic wave generating array (204), the frequency of which is 20~40kHz and the power density is 0.1~0.3W / cm².

7. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The conical micropore (105) has an inlet diameter of 0.5~1mm and an outlet diameter of 12μm~50μm, exhibiting a gradient contraction structure.

8. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The inner wall of the reaction tank and the surface of the baffle (201) are coated with an anti-corrosion coating; the hydrophilic metal oxide is selected from Al2O3 and TiO2; the anti-corrosion coating is selected from fluorocarbon resin coating and special epoxy resin layer.

9. The wastewater treatment device based on micro / nano bubbles according to claim 1, characterized in that, The thickness of the hydrophobic passivation layer is 1~3μm; the thickness of the first Al2O3 hydrophilic layer is 30~50μm; and the thickness of the second Al2O3 hydrophilic layer is 1~2μm.

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