Wastewater heavy metal resource recycling device and method based on ozone micro-nano bubbles

Abstract

The invention provides a waste water heavy metal resource recycling device and method based on ozone micro-nano bubbles, and belongs to the technical field of waste water treatment equipment, and the waste water heavy metal resource recycling device comprises an ozone generation system, a micro-nano bubble generator and a rectangular plug flow continuous flow reactor. The ozone generation system generates high-concentration ozone gas, and the micro-nano bubble generator generates ozone micro-nano bubbles and injects the ozone micro-nano bubbles into the reactor. The reactor consists of a micro-nano bubble reaction unit, a precipitation coupling membrane separation unit and a detection system, wherein the reaction unit is provided with a circulation path. Under normal temperature and normal pressure, complex-state heavy metal ions are converted into micro-nano metal oxide particles with the particle size of 10-1000 nm in situ in one step through ozone micro-nano bubble interface oxidation, no auxiliary chemical reagent or high-temperature roasting is needed, meanwhile, the particles catalyze ozone in situ to generate OH, and synergistic degradation of organic pollutants is promoted. The wastewater is subjected to precipitation coupling membrane separation to recover high-value micro-nano metal oxide products; the removal rate of heavy metals is more than 90%, the value of the product is increased by 10-50 times, and TDS (total dissolved solids) is prevented from rising.

Description

Wastewater Heavy Metal Resource Recovery Device and Method Based on Ozone Micro-Nano Bubbles Technical Field

[0001] This invention relates to the fields of environmental engineering and materials synthesis technology, specifically to an apparatus and method for treating complex wastewater containing complexed heavy metals and organic pollutants using ozone micro-nano bubbles (O3-MNBs) technology, achieving in-situ conversion of heavy metal ions into high-value micro-nano metal oxide particles and resource recovery. This apparatus and method are applicable to the treatment of complex wastewater generated in industries such as electroplating, textiles, and chemicals. Background Technology

[0002] With the acceleration of global industrialization and increasingly stringent environmental protection standards, the development of green and sustainable heavy metal wastewater treatment technologies has become an urgent need in the environmental field. Traditional heavy metal wastewater (such as electroplating wastewater) contains a large number of complexed heavy metal ions (such as Cu). 2+ Zn 2+ Ni 2+ These complexes, formed with EDTA, citric acid, etc., are highly stable and difficult to remove effectively using conventional methods. Typically, a complex-breaking agent (such as sodium sulfide, sodium hypochlorite, or Fenton's reagent) is added first to disrupt the complex structure, followed by the addition of a large amount of precipitant (such as NaOH, Na2S, or lime) to generate hydroxide or sulfide precipitates. This process not only consumes a large amount of reagents (the total dosage of complex-breaking agent + precipitant is often >5 g / L), leading to a significant increase in total dissolved solids (TDS) in the effluent (an increase of hundreds to thousands of mg / L of salt), affecting subsequent reuse or discharge; the resulting heavy metal sludge is hazardous waste, and if it is to be utilized as a resource, it needs to be roasted at high temperatures (500-900°C) to convert it into metal oxides, further increasing energy consumption and carbon emissions. Direct incineration or landfilling results in resource waste and the risk of secondary pollution.

[0003] Existing ozone oxidation technology can simultaneously break down complexes and degrade organic matter, but the treated heavy metal ions still require additional precipitants for precipitation and recovery. The products are low-value hydroxides or coarse particles, failing to directly yield high-value micro / nano metal oxides, and the addition of reagents still leads to an increase in TDS. Ozone micro / nano bubble technology, due to its excellent mass transfer, the charge effect on the surface of micro / nano bubbles, and the disintegration cavitation effect, can not only efficiently break down complexes but also adsorb heavy metal ions at the bubble interface. Through the local pH effect and high-concentration •OH environment at the interface, it promotes the in-situ generation of micro / nano metal oxides from metal ions on the bubble surface, achieving the direct conversion of waste metal ions into high-value micro / nano catalytic materials. Simultaneously, the generated micro / nano metal oxides also have autocatalytic significance for further degrading organic matter with ozone. However, existing technologies only utilize micro / nano bubbles to improve ozone utilization or perform simple precipitation and recovery, failing to achieve a complete process for the in-situ one-step conversion of heavy metal ions into high-value micro / nano metal oxide particles and the formation of an autocatalytic closed loop without auxiliary reagents or calcination. Summary of the Invention

[0004] The purpose of this invention is to provide a wastewater heavy metal resource recovery device and method based on ozone micro-nano bubbles, so as to solve at least one of the technical problems existing in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a wastewater heavy metal resource recovery device based on ozone micro-nano bubbles, comprising an ozone generating system, a micro-nano bubble generator, and a rectangular plug flow continuous flow reactor; the ozone generating system includes an oxygen production system and a cooling system, used to generate ozone gas with a concentration of 50-200 mg / L; the micro-nano bubble generator is connected to the ozone generating system, used to generate ozone micro-nano bubbles with a diameter of 0.01-10 μm and a bubble density greater than 10. 8The rectangular plug flow continuous flow reactor is equipped with a wastewater inlet (inlet / outlet) and an outlet for the micro / nano bubble generator. This allows for in-situ, one-step synthesis of micro / nano metal oxide particles with a particle size of 10-1000 nm through interfacial oxidation via ozone nanobubbles under ambient temperature and pressure conditions. The particles are selected from micro / nano CuO, micro / nano ZnO, micro / nano MnO2, micro / nano Fe2O3, micro / nano Co3O4, micro / nano NiO, or combinations thereof. The synthesis process requires no auxiliary chemical reagents or high-temperature calcination, achieving different concentrations (10-2000 nm). The process achieves efficient removal and resource conversion of complexed heavy metal ions (mg / L). The rectangular plug flow continuous flow reactor consists of a micro-nano bubble reaction unit, a precipitation coupled membrane separation unit, and a detection system. The micro-nano bubble reaction unit is designed with a circulation path, which is connected to the micro-nano bubble generator to form a closed loop, used to achieve rapid recovery of the micro-nano metal oxide particles. The catalytic process is completed by controlling the reaction time. At the same time, the generated micro-nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient precipitation area to directly separate the catalyst from the wastewater.

[0007] As a further limitation of the first aspect of the present invention, the micro / nano bubble generator is equipped with an interface oxidation module, which induces a local high pressure / high temperature effect through the dynamic stirring reaction of ozone micro / nano bubbles, promoting the decomplexing, oxidation and micro / nano crystallization of complexed heavy metal ions without the need for separate mechanical stirring; the rectangular plug flow continuous flow reactor has a rectangular pool structure, supporting concentration gradient control and efficient mass transfer under continuous operation, with a volume ratio of reaction zone to precipitation zone of 1:3; the circulation path includes a reflux pipeline (flow rate 0.1-1 L / min), used to circulate part of the reaction mixture to the micro / nano bubble generator, achieving a heavy metal removal rate of greater than 90%.

[0008] As a further limitation of the first aspect of the invention, the micro / nano bubble reaction unit may optionally be equipped with an ultrasonic-assisted disintegrator (frequency 20-40 kHz) and a pH dynamic feedback sensor (response time < 5 s), the sensor being placed inside the reactor to maintain pH 6-8 and optimize •OH concentration (>10). -5 M), to enhance the effects of multiple metal ions (such as Mn) 2+ and Fe 2+ The in-situ micro / nano crystallization efficiency and particle size control (<50 nm) of O3-MNBs are achieved, while the natural turbulence of O3-MNBs is used to achieve uniform mixing of continuous flow.

[0009] As a further limitation of the first aspect of the present invention, the precipitation coupled membrane separation unit is integrated inside the reactor, including a sufficient precipitation zone (volume percentage > 60%), an overflow pool (located at the end of the precipitation zone, used to regulate the flow rate < 0.5 m / h) and a subsequent membrane filtration system (ultrafiltration membrane, pore size < 50 nm), which enables a rapid recovery rate of more than 95% for the micro-nano metal oxide particles. The recovered product is used as a high-value resource product and integrated into the reuse path, suitable for linear flow separation with a rectangular plug flow design.

[0010] As a further limitation of the first aspect of the invention, the detection system is placed inside the reactor and equipped with an online electrochemical sensor for monitoring the concentration of multiple metal ions (including Cu). 2+ Zn 2+ Mn 2+ Fe 2+ / Fe 3+ Co 2+ and Ni 2+ The device includes a gaseous ozone detection probe for real-time monitoring of ozone gas concentration, a dissolved ozone online detection probe for assessing aqueous ozone concentration, and an ORP potential sensor for monitoring oxidation-reduction potential (range 0-1000 mV). The device further includes an external integrated monitoring system equipped with an online COD analyzer for assessing organic pollutant removal efficiency, and a temperature / flow rate sensor for verifying the efficiency of micro / nano metal oxide recovery under continuous flow conditions.

[0011] In a second aspect, the present invention provides a method for the resource recovery of heavy metals from wastewater using the apparatus described in the first aspect, comprising the following steps:

[0012] (a) In the rectangular plug flow continuous flow reactor, composite wastewater containing complexed heavy metal ions and organic pollutants at different concentrations (10-2000 mg / L) is introduced through the wastewater inlet (inlet outlet), and ozone micro-nano bubbles are injected through the outlet of the micro-nano bubble generator. The complexed heavy metal ions are selected from Cu. 2+ Zn 2+ Mn 2+ Fe 2+ / Fe 3 + Co 2+ and Ni 2+ Or a combination thereof, wherein the organic pollutant is selected from EDTA complexing agents, phenolic compounds, dyes or cyanides;

[0013] (b) Under continuous flow conditions at ambient temperature and pressure, ozone micro-nano bubbles in the micro-nano bubble reaction unit are strongly oxidized and decomplexed, and ozone micro-nano bubbles are dynamically stirred and circulated. Micro-nano metal oxide particles with a particle size of 10-1000 nm are synthesized in situ in one step. The synthesis process does not require any auxiliary chemical reagents or high-temperature calcination, thus achieving efficient removal and resource conversion of heavy metal ions.

[0014] (c) The micro-nano metal oxide particles are rapidly recovered through the precipitation coupling membrane separation unit. The catalytic process is completed by controlling the reaction time. At the same time, the generated micro-nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient precipitation area to directly separate the catalyst from the wastewater, realizing the recovery of micro-nano metal oxides as high-value resource products and the removal of organic matter.

[0015] As a further limitation of the second aspect of the present invention, the in-situ synthesis process described in step (b) is carried out under continuous flow conditions with a reaction time of 10-60 minutes and a gas flow rate of 0.1-1 L / min, and the turbulence effect and circulation pathway of ozone micro-nano bubbles are used to ensure the uniformity of the plug gradient reaction.

[0016] As a further limitation of the second aspect of the invention, the catalytic process in step (c) increases the •OH production by at least 2 times compared to the pure ozone system, and the organic pollutant degradation rate constant k is greater than 0.1 min. -1 Free radical capture experiments (such as tert-butanol quenching) have verified that •OH is the main active species, making it suitable for the continuous treatment of wastewater containing multiple metals.

[0017] As a further limitation of the second aspect of the present invention, the method has a heavy metal removal rate of greater than 90%, a total organic carbon (TOC) removal rate of greater than 85%, and the initial concentration of the composite wastewater is 10-2000 mg / L for heavy metal ions and 20-100 mg / L for organic pollutants, supporting continuous operation on an industrial scale.

[0018] Thirdly, this invention provides a high-value resource-based micro / nano metal oxide product prepared by the method described in the second aspect. This product is synthesized in situ in a one-step process by in-situ oxidation of complexed heavy metal ions of different concentrations in composite wastewater using ozone micro / nano bubbles in a rectangular plug flow continuous flow reactor. The product comprises micro / nano CuO, micro / nano ZnO, micro / nano MnO2, micro / nano Fe2O3, micro / nano Co3O4, micro / nano NiO, or their composites, with particle sizes of 10-1000 nm. It exhibits surface •OH catalytic activity (specific surface area > 50 m² / g) and magnetic recyclability, and can be used in advanced oxidation processes, photocatalysis, or electrocatalysis applications.

[0019] Beneficial effects of this invention:

[0020] (1) Green and sustainable, with no secondary pollution: It requires no complexing agents, precipitants and high-temperature calcination, the TDS of the effluent hardly increases (the ozone decomposition product is only oxygen), energy consumption is reduced by more than 70%, and the salt accumulation, sludge hazardous waste and calcination carbon emissions of traditional processes are completely avoided, which meets the "dual carbon" target and clean production requirements.

[0021] (2) Significant economic value enhancement: By utilizing the interfacial charge, local pH, and cavitation effect of ozone micro-nano bubbles, waste heavy metal ions can be directly converted into high-value micro-nano metal oxides (micro-nano CuO has a market price of 50-200 USD / kg, and micro-nano ZnO has a market price of 50-150 USD / kg, which is 10-50 times more valuable than ordinary oxides). Taking wastewater containing 500 mg / L of Cu as an example, each cubic meter of wastewater can generate about 0.5 kg of micro-nano CuO, with a conservative value of more than 50 USD, realizing the transformation from environmental liability to economic asset.

[0022] (3) Intrinsic self-catalytic synergistic mechanism: The surface of the micro-nano metal oxide particles generated in situ is rich in active sites, which form an autocatalytic cycle with ozone, increasing the production of •OH by more than 2 times, realizing the mutual promotion of heavy metal conversion and organic matter degradation, without the need for external catalysts, and greatly improving ozone utilization.

[0023] (4) Wide range of applications and industrialization potential: It is suitable for complex wastewater with heavy metal concentration of 10-2000 mg / L, with heavy metal removal rate >90% and TOC removal rate >85%. It features continuous flow operation and circulation path design, which facilitates industrial scale-up and completely overturns the traditional "removal-disposal" model, turning to a new "manufacturing-value-added" paradigm.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the overall structure of the wastewater heavy metal resource recovery device based on ozone micro-nano bubbles according to an embodiment of the present invention. It shows the connection relationship between the ozone generation system, the micro-nano bubble generator and the rectangular plug flow continuous flow reactor, as well as the wastewater inlet, the ozone micro-nano bubble outlet and the circulation path.

[0027] Figure 2 is a cross-sectional view of the rectangular plug flow continuous flow reactor described in an embodiment of the present invention, which shows the location of the micro-nano bubble reaction unit, the sedimentation coupled membrane separation unit (including gravity sedimentation zone, overflow pool and ultrafiltration membrane), the detection system, the volume ratio of the reaction zone to the sedimentation zone (1:3) and the circulation path.

[0028] Figure 3 is a process flow diagram of the wastewater heavy metal resource recovery method based on ozone micro-nano bubbles according to an embodiment of the present invention, illustrating the entire process of wastewater injection, in-situ synthesis of micro-nano metal oxide particles by ozone micro-nano bubble interface oxidation, autocatalytic synergistic degradation, precipitation coupling membrane separation, and high-value product recovery.

[0029] Figure 4 shows a photograph of the recovered micro / nano metal oxide particles according to an embodiment of the present invention. Electron microscopy (SEM) and energy dispersive spectroscopy (EDS) characterization examples show that the particle size distribution is in the range of 50-200 nm.

[0030] The components include: 1. Ozone generator; 2. Micro / nano bubble generator; 3. Reaction zone; 4. Circulation path; 5. Precipitation membrane coupling unit; 6. Gravity precipitation zone; 7. Overflow tank; 8. Ultrafiltration membrane; 9. Online electrochemical sensor; 10. Gaseous / dissolved ozone probe; 11. OPR sensor; 12. COD analyzer; and 13. Circulation pump. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0034] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0035] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0036] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In the description of this specification, the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this technology and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this technology.

[0038] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of these terms in this art according to the specific circumstances.

[0039] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0040] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0041] As shown in Figures 1 to 4, this invention provides a wastewater heavy metal resource recovery device and method based on ozone micro-nano bubbles. Through the unique charge effect, cavitation effect, local high-pressure / high-temperature microenvironment, and high concentration of •OH at the ozone micro-nano bubble interface, under normal temperature and pressure conditions, without any auxiliary chemical reagents or high-temperature calcination, complexed heavy metal ions are converted in situ into high-value micro-nano metal oxide particles with a particle size of 10-1000 nm in one step. Simultaneously, the in-situ generated particles self-catalyze the generation of •OH from ozone, achieving synergistic and efficient degradation of organic pollutants. Finally, high-value resource products are directly recovered through precipitation coupling membrane separation. This invention completely eliminates the dependence on complexing agents, precipitants, and calcination in traditional processes, avoiding increased TDS and hazardous waste generation in the effluent. It achieves excellent performance with a heavy metal removal rate greater than 90%, a TOC removal rate greater than 85%, and product value enhancement of 10-50 times. It truly transforms environmental liabilities into economic assets, embodying a green and sustainable new paradigm of "treating waste with waste and turning waste into treasure," and has significant theoretical innovation value and broad industrial application prospects.

[0042] In one specific embodiment, the wastewater heavy metal resource recovery device based on ozone micro-nano bubbles includes an ozone generation system, a micro-nano bubble generator, and a rectangular plug flow continuous flow reactor.

[0043] The ozone generation system includes an oxygen production system and a cooling system, used to generate ozone gas with a concentration of 50-200 mg / L.

[0044] The micro / nano bubble generator is connected to the ozone generation system and is used to generate ozone micro / nano bubbles with a diameter of 0.01-10 μm and a bubble density greater than 10. 8 The number of cells / mL is connected to the reactor via the output port.

[0045] The rectangular plug flow continuous flow reactor is equipped with a wastewater inlet (inlet / outlet) and an outlet of the micro / nano bubble generator. It is used to synthesize micro / nano metal oxide particles with a particle size of 10-1000 nm in situ through interfacial oxidation by ozone micro / nano bubbles under normal temperature and pressure aqueous phase conditions. The particles are selected from micro / nano CuO, micro / nano ZnO, micro / nano MnO2, micro / nano Fe2O3, micro / nano Co3O4, micro / nano NiO or combinations thereof. The synthesis process does not require any auxiliary chemical reagents or high-temperature calcination, achieving efficient removal and resource conversion of complexed heavy metal ions of different concentrations (10-2000 mg / L).

[0046] The rectangular plug flow continuous flow reactor consists of a micro-nano bubble reaction unit, a sedimentation coupled membrane separation unit, and a detection system. The micro-nano bubble reaction unit is designed with a circulation path and is connected to the micro-nano bubble generator to form a closed loop, which is used to realize the rapid recovery of the micro-nano metal oxide particles. The catalytic process is completed by controlling the reaction time. At the same time, the generated micro-nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient sedimentation area to directly separate the catalyst and wastewater.

[0047] The method includes the following steps:

[0048] (a) In the rectangular plug flow continuous flow reactor, composite wastewater containing complexed heavy metal ions and organic pollutants of different concentrations (10-2000 mg / L) is introduced through the wastewater inlet, and ozone micro-nano bubbles are injected.

[0049] (b) Under continuous flow conditions at ambient temperature and pressure, through the strong oxidation and decomplexation of ozone micro-nano bubbles in the micro-nano bubble reaction unit, as well as the dynamic stirring reaction and circulation pathway of the ozone micro-nano bubbles themselves, micro-nano metal oxide particles with a particle size of 10-1000 nm are synthesized in situ in one step, thereby achieving efficient removal and resource conversion of heavy metal ions.

[0050] (c) The micro-nano metal oxide particles are rapidly recovered through the precipitation coupling membrane separation unit. The catalytic process is completed by controlling the reaction time. At the same time, the generated micro-nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient precipitation area to directly separate the catalyst from the wastewater, realizing the recovery of micro-nano metal oxides as high-value resource products and the removal of organic matter.

[0051] The wastewater heavy metal resource recovery device and method based on ozone micro-nano bubbles provided in this embodiment have the following core innovations in the interdisciplinary field of environmental engineering and materials synthesis, realizing a paradigm shift from "pollutant removal" to "high-value material manufacturing":

[0052] (1) A one-step in-situ synthesis process for micro / nano metal oxide particles was proposed and realized at room temperature and pressure, without auxiliary chemical reagents or high-temperature calcination. Utilizing the unique charge effect, disintegration cavitation effect, local high-pressure / high-temperature microenvironment, and high concentration of hydroxyl radicals (•OH) at the ozone micro / nano bubble interface, complexed heavy metal ions (Cu) were directly synthesized. 2+ Zn 2+ Mn 2+ Fe 2+ / Fe 3+ Co 2+ and Ni 2+(etc.) are oxidized and crystallized in situ on the surface of bubbles into micro-nano metal oxide particles with a particle size of 10-1000 nm, completely eliminating the need for complex-breaking agents, precipitants and subsequent roasting steps required by traditional processes, thus avoiding the increase of TDS in effluent and the generation of hazardous waste.

[0053] (2) A direct resource-based conversion pathway of “waste heavy metal ions → high-value micro-nano catalytic materials” has been constructed. The products are no longer low-value hydroxides or coarse-particle oxides (market price 6-20 USD / kg), but micro-nano metal oxides with high specific surface area (>50 m² / g) and excellent catalytic performance (micro-nano CuO 50-200 USD / kg, micro-nano ZnO 50-150 USD / kg). The product value can be increased by more than 10-50 times per ton of wastewater treated, turning environmental liabilities into economic assets.

[0054] (3) The intrinsic catalytic synergistic mechanism between micro / nano metal oxide particles and ozone was revealed and utilized.

[0055] The surface of the in-situ generated micro- and nano-sized metal oxide particles is rich in Lewis acid sites, which can significantly catalyze the decomposition of ozone to produce •OH (the yield is ≥2 times higher than that of the pure ozone system), forming a positive feedback loop in which "heavy metal conversion products in turn accelerate the degradation of organic matter". This achieves the dual goals of heavy metal resource utilization and efficient synergistic degradation of organic pollutants without the need for external catalysts.

[0056] (4) A rectangular plug flow continuous flow reactor integrating "micro-nano bubble reaction - circulation path - precipitation coupling membrane separation" was invented. Through the 1:3 volume ratio of reaction zone to precipitation zone, closed circulation path and overflow pool + ultrafiltration membrane integrated design, efficient synthesis, rapid separation (recovery rate >95%) and recycling of micro and nano particles under continuous flow conditions are achieved. The system has a compact structure and stable operation, completely eliminating the dependence of traditional processes on mechanical stirring and external reagents.

[0057] In one specific embodiment, the ozone generation system employs corona discharge, equipped with a pressure swing adsorption oxygen generation system (oxygen purity >90%) and a water cooling system (cooling water temperature <15°C), controlling the ozone gas concentration at 50-200 mg / L. The micro / nano bubble generator utilizes high-pressure dissolved gas release combined with fluid shear principles to generate ozone with a diameter of 0.01-10 μm and a density >10. 8 Ozone micro / nanobubbles per mL. The rectangular plug-flow continuous flow reactor has a rectangular tank structure with a reaction zone to sedimentation zone volume ratio of 1:3. A circulation path (return pipeline, flow rate 0.1-1 L / min) is provided within the reaction zone. The sedimentation-coupled membrane separation unit includes a gravity sedimentation zone (volume percentage >60%), an overflow tank (surface loading <0.5 m / h), and an ultrafiltration membrane (pore size <50 nm). The detection system is equipped with an online electrochemical sensor (monitoring Cu).2+ Zn 2+ (etc.), gaseous / dissolved ozone probe, ORP sensor and COD analyzer.

[0058] In one specific embodiment, the above-described apparatus is used to treat Cu-EDTA-containing electroplating wastewater, the wastewater composition of which is: Cu 2+ The reactor composition was 500 mg / L EDTA, 800 mg / L phenol, pH 7.0, and a flow rate of 10 L / h. Ozone dosage was 100 mg / L, with a recirculation ratio of 30%. Wastewater entered the reactor through the inlet and, after 30 minutes of contact with ozone micro-nano bubbles, achieved a Cu removal rate of 98% and a TOC removal rate of 92%. The recovered micro-nano CuO particles had a particle size of 20-200 nm and a specific surface area of ​​85 m² / g. No significant increase in effluent TDS was observed, and the particles were directly used as a high-value catalyst material.

[0059] In one specific embodiment, the above-described apparatus is used to treat polymetallic composite wastewater containing Cu. 2+ 300 mg / L, Zn 2+ 200 mg / L, Ni 2+ 150 mg / L, Mn 2+ 100 mg / L and dye-related organic compounds. Under the same equipment and conditions, the total heavy metal removal rate was 95%, and the TOC removal rate was 90%. Micro-nano composite metal oxide particles (micro-nano CuO / ZnO / MnO2 / NiO) with a specific surface area >70 m² / g were recovered and significantly enhanced when used as photocatalytic materials.

[0060] In one specific embodiment, high-concentration wastewater treatment and large-scale verification were carried out, and the wastewater contained Cu. 2+ 1500 mg / L, complexing agent, and organic matter. Ozone dosage 150 mg / L, treatment capacity 100 L / h, continuous operation for 72 h. Heavy metal removal rate 93%, particulate recovery rate 96%, system stability, effluent TDS increase <50 mg / L. Recovery of micro / nano CuO yield approximately 0.75 kg / m³ of wastewater, demonstrating significant economic value.

[0061] Self-catalytic effect verification: Comparative experiment: In the same wastewater, using the pure ozone micro-nano bubble system as a baseline, the •OH production increased by 2.8 times after the in-situ generation of micro-nano metal oxide particles, and the organic matter degradation rate constant k increased from 0.05 min. -1 Increased to 0.14 min -1 This confirms the autocatalytic synergistic mechanism.

[0062] The above embodiments demonstrate that the present invention can operate stably under different wastewater compositions and high concentration conditions, achieving efficient resource recovery of heavy metals and synergistic degradation of organic matter. In practical applications, the ozone concentration, circulation ratio, and reaction time can be fine-tuned according to the wastewater characteristics.

[0063] Those skilled in the art should understand that the above embodiments are merely illustrative examples, and the apparatus and method described in this invention are also applicable to other types of heavy metal complex wastewater (such as wastewater containing complexed ions such as Cr, Cd, and Pb), as well as industrial applications of different treatment scales. Other existing or future wastewater treatment scenarios suitable for adopting the technical solutions of this invention should be included within the scope of protection of this invention and are incorporated herein by reference.

[0064] In practical engineering applications, the specific arrangement and connection methods of the rectangular plug flow continuous flow reactor, ozone generation system, micro-nano bubble generator and other modules described in this invention are not limited to the forms described in the embodiments. As long as effective contact between ozone micro-nano bubbles and wastewater, and in-situ synthesis and recovery of micro-nano metal oxide particles can be achieved, they are equivalent substitutions of this invention and are all within the protection scope of this invention.

[0065] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. A wastewater heavy metal resource recovery device based on ozone micro-nano bubbles, characterized in that, include: An ozone generation system, a micro / nano bubble generator, and a rectangular plug-flow continuous flow reactor are included. The ozone generation system comprises an oxygen production system and a cooling system for generating ozone gas. The micro / nano bubble generator is connected to the ozone generation system to generate ozone micro / nano bubbles and is connected to the reactor via an output port. The rectangular plug-flow continuous flow reactor is equipped with a wastewater inlet and an output port of the micro / nano bubble generator, used to synthesize micro / nano metal oxide particles in situ in a one-step manner under ambient temperature and pressure aqueous phase conditions through interfacial oxidation of ozone micro / nano bubbles. The rectangular plug-flow continuous flow reactor consists of a micro / nano bubble reaction unit, a precipitation coupling membrane separation unit, and a detection system. The micro / nano bubble reaction unit includes a circulation path connected to the micro / nano bubble generator to form a closed loop for recovering the micro / nano metal oxide particles. The catalytic process is completed by controlling the reaction time. Simultaneously, the generated micro / nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient precipitation zone to directly separate the catalyst from the wastewater.

2. The wastewater heavy metal resource recovery device based on ozone micro-nano bubbles according to claim 1, characterized in that, The micro / nano bubble generator is equipped with an interface oxidation module, which induces a local high pressure / high temperature effect through the dynamic stirring reaction of ozone micro / nano bubbles, promoting the decomplexing, oxidation, and micro / nano crystallization of complexed heavy metal ions; the rectangular plug flow continuous flow reactor has a rectangular pool structure, which supports concentration gradient control and efficient mass transfer under continuous operation; the circulation path includes a reflux pipeline for circulating part of the reaction mixture to the micro / nano bubble generator.

3. The wastewater heavy metal resource recovery device based on ozone micro-nano bubbles according to claim 1, characterized in that, The micro-nano bubble reaction unit can be optionally equipped with an ultrasonic-assisted disintegrator and a pH dynamic feedback sensor. The pH dynamic feedback sensor is placed inside the reactor to maintain pH 6-8 and optimize the •OH concentration, thereby enhancing the in-situ micro-nano crystallization efficiency and particle size control of multiple metal ions. At the same time, it utilizes the natural turbulence of ozone micro-nano bubbles to achieve uniform mixing through continuous flow.

4. The wastewater heavy metal resource recovery device based on ozone micro-nano bubbles according to claim 1, characterized in that, The precipitation-coupled membrane separation unit is integrated inside the reactor and includes a precipitation zone, an overflow tank, and a subsequent membrane filtration system. It is used for the rapid recovery of the micro-nano metal oxide particles, integrates a reuse path, and is suitable for linear flow separation with a rectangular plug flow design.

5. The wastewater heavy metal resource recovery device based on ozone micro-nano bubbles according to claim 1, characterized in that, The detection system is located inside the reactor and is equipped with an online electrochemical sensor for monitoring the concentration of multiple metal ions, a gaseous ozone detection probe for real-time monitoring of ozone gas concentration, an online dissolved ozone detection probe for assessing the ozone concentration in the aqueous phase, and an ORP potential sensor for monitoring redox potential.

6. A method for the resource recovery of heavy metals from wastewater using the apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: (a) In the rectangular plug flow continuous flow reactor, composite wastewater containing complexed heavy metal ions and organic pollutants of different concentrations is introduced through the wastewater inlet, and ozone micro-nano bubbles are injected through the output port of the micro-nano bubble generator; (b) Under continuous flow conditions at ambient temperature and pressure, micro-nano metal oxide particles are synthesized in situ in one step through the strong oxidation and decomplexation of ozone micro-nano bubbles in the micro-nano bubble reaction unit, as well as the dynamic stirring reaction and circulation pathway of the ozone micro-nano bubbles themselves; (c) The micro-nano metal oxide particles are rapidly recovered through the precipitation coupling membrane separation unit. The catalytic process is completed by controlling the reaction time. At the same time, the generated micro-nano metal oxide particles further catalyze ozone in situ to promote the synergistic degradation of pollutants. Finally, the wastewater enters a sufficient precipitation area to directly separate the catalyst and wastewater, realizing the recovery of micro-nano metal oxides as high-value resource products and the removal of organic matter.

7. The method for resource recovery of heavy metals from wastewater according to claim 6, characterized in that, The in-situ synthesis process described in step (b) is carried out under continuous flow conditions with a reaction time of 10-60 minutes and a gas flow rate of 0.1-1 L / min. The turbulence effect and circulation pathway of ozone micro-nano bubbles are used to ensure the uniformity of the plug gradient reaction.

8. The method for resource recovery of heavy metals from wastewater according to claim 6, characterized in that, The catalytic process described in step (c) increases the •OH production by at least 2 times compared to the pure ozone system, and the organic pollutant degradation rate constant k is greater than 0.1 min. -1 Free radical capture experiments verified that •OH is the main active species and is suitable for the continuous treatment of wastewater containing multiple metals.

9. The method for resource recovery of heavy metals from wastewater according to claim 6, characterized in that, The method achieves a heavy metal removal rate greater than 90% and a total organic carbon removal rate greater than 85%. The initial concentration of the composite wastewater is 10-2000 mg / L for heavy metal ions and 20-100 mg / L for organic pollutants.

10. A high-value resource-based product of micro / nano metal oxides prepared by the method described in claims 6-9, characterized in that, The product is synthesized in situ in a one-step process by in-situ oxidation of complexed heavy metal ions of different concentrations in composite wastewater using ozone micro-nano bubbles in a rectangular plug flow continuous flow reactor. The product consists of micro-nano CuO, micro-nano ZnO, micro-nano MnO2, micro-nano Fe2O3, micro-nano Co3O4, micro-nano NiO or their composites with a particle size of 10-1000 nm. It has surface •OH catalytic activity and magnetic recyclability and can be used in advanced oxidation processes, photocatalysis or electrocatalysis applications.

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