A self-supplied H2O2 magnetic catalytic enhanced MBR water purification system and method

Abstract

This invention discloses a self-supplied H2O2 magnetic catalytic enhanced MBR water purification system and method, belonging to the field of environmental engineering and water treatment technology. The raw water supply pipeline or the outlet pipeline of the alcohol-based hydrogen peroxide in-situ generation unit is also connected to an acid dosing pipeline. The outlet pipelines of the raw water supply pipeline, the alcohol-based hydrogen peroxide in-situ generation unit, and the catalyst supply pipeline are all connected to a tubular mixer. The outlet of the tubular mixer is sequentially connected to a magnetic catalytic photo-Fenton reactor, a magnetic separator, an activated carbon quenching tank, and a membrane bioreactor. The magnetic separator is connected to the catalyst supply pipeline via a catalyst recycling pipeline. The anode chamber of the alcohol-based hydrogen peroxide in-situ generation unit is connected to an alcohol waste liquid source, and the cathode chamber is connected to an air source. The anode and cathode are connected via an external circuit. This invention uses alcohol waste liquid and air as raw materials to generate hydrogen peroxide in-situ solely under conditions driven by the system's self-generated potential difference, and achieves deep removal of nutrients such as nitrogen and phosphorus.

Description

Technical Field

[0001] This invention relates to the fields of environmental engineering and water treatment technology, specifically to a self-supplied H2O2 magnetic catalytic enhanced MBR water purification system and method. Background Technology

[0002] Eutrophication of lakes and reservoirs and the resulting cyanobacterial blooms have become a major challenge in global water environment governance. In recent years, with accelerated urbanization and the continuous accumulation of agricultural non-point source pollution, cyanobacterial blooms have frequently occurred in key lakes and reservoirs such as Taihu Lake, Chaohu Lake, and Dianchi Lake, as well as numerous small and medium-sized drinking water sources in China. Cyanobacterial blooms not only severely damage the structure and function of aquatic ecosystems, leading to a sharp decline in dissolved oxygen and the death of large numbers of aquatic organisms, but also release highly toxic secondary metabolites such as microcystins (MCs) and nodotoxins (NODs). These algal toxins are highly stable, hepatotoxic, and carcinogenic, and are difficult to completely remove using conventional water treatment processes.

[0003] Existing treatment technologies for cyanobacterial blooms and their toxin pollution mainly include physical methods, chemical oxidation methods, advanced oxidation methods, and biological methods. However, each has significant shortcomings: Physical methods, such as dredging and flotation, can only remove cyanobacterial cells and cannot effectively degrade intracellular and extracellular toxins, easily causing secondary pollution, and are characterized by low treatment efficiency and high cost. Chemical oxidation methods, such as ozone, sodium hypochlorite, and hydrogen peroxide, rely on purchasing high-concentration oxidants, posing safety risks related to the storage, transportation, and application of hazardous chemicals, as well as high costs, and are prone to producing disinfection byproducts. Advanced oxidation technologies, such as Fenton and photo-Fenton, require continuous addition of agents such as hydrogen peroxide and ferrous salts, resulting in high operational complexity and difficulty in ensuring a stable supply of agents in remote areas. Furthermore, traditional Fenton reactions suffer from problems such as large iron sludge production and a narrow pH range. Biological methods, such as microbial degradation and ecological floating beds, have long treatment cycles and are greatly affected by fluctuations in ambient temperature and water quality, making them unsuitable for emergency treatment needs during cyanobacterial blooms. Furthermore, most of the aforementioned technologies are energy-intensive and rely on stable high-voltage power grids, making them difficult to scale up in rural areas and remote lake regions with weak power grids in my country, and thus unable to meet the needs of algal bloom control in decentralized water bodies. On the other hand, my country's chemical, textile, and pharmaceutical industries generate large quantities of polyol wastewater such as ethylene glycol, propylene glycol, and glycerin annually. This type of wastewater is characterized by high COD concentrations, poor biodegradability, and high treatment costs. Traditional incineration and biological treatment methods have extremely low resource utilization rates and also generate carbon emissions and secondary pollution. How to efficiently utilize waste alcohol and wastewater has become an urgent environmental challenge for the industry.

[0004] Therefore, developing a water purification technology that does not require the purchase of oxidants, does not rely on high-voltage power grids, enables in-situ self-sufficiency of oxidants, and allows for the recycling of catalysts has significant practical implications and application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems in the prior art and provide a self-supplied H2O2 magnetic catalytic enhanced MBR water purification system and method that does not require the purchase of external oxidants, does not rely on high-voltage power grids, can achieve in-situ self-supplied oxidants, and allows for the recycling of catalysts.

[0006] This invention provides a self-supplying H2O2 magnetic catalytic enhanced MBR water purification system, comprising a raw water supply pipeline, an alcohol-based hydrogen peroxide in-situ generation unit, a catalyst supply pipeline, a tubular mixer, a magnetic catalytic photo-Fenton reactor, a magnetic separator, an activated carbon quenching tank, a membrane bioreactor, and a catalyst reuse pipeline; the raw water supply pipeline or the outlet pipeline of the alcohol-based hydrogen peroxide in-situ generation unit is also connected to an acid dosing pipeline, and the outlet pipelines of the raw water supply pipeline, the alcohol-based hydrogen peroxide in-situ generation unit, and the catalyst supply pipeline are all connected to the tubular mixer to mix raw water, hydrogen peroxide, acid, and magnetic photocatalyst; the outlet of the tubular mixer is sequentially connected to the magnetic catalytic photo-Fenton reactor, the magnetic separator, the activated carbon quenching tank, and the membrane bioreactor; the magnetic separator is connected to the catalyst supply pipeline via the catalyst reuse pipeline; The in-situ hydrogen peroxide generation unit includes an anode chamber, a cathode chamber, an ion exchange membrane disposed between the anode chamber and the cathode chamber, an anode, and a cathode. The anode chamber is connected to an alcohol waste liquid source, and the cathode chamber is connected to an air source. The anode and cathode are connected via an external circuit to generate hydrogen peroxide in situ using an anodic oxidation reaction and a cathode two-electron reduction reaction without the need for an external power supply.

[0007] Preferably, the alcohol waste liquid is ethylene glycol waste liquid; the anode is an anode supported on a PtNiCu / C catalyst, the cathode is a gas diffusion cathode; and the cathode chamber is equipped with an aeration device.

[0008] Preferably, the magnetic separator includes a magnetic rotating shaft and a scraper. The magnetic rotating shaft is used to adsorb magnetic photocatalyst under a high gradient magnetic field, and the scraper is attached to the surface of the magnetic rotating shaft to scrape out the adsorbed catalyst and guide it to the catalyst recycling pipeline.

[0009] Preferably, the system further includes an ecologically stable sedimentation unit, the inlet of which is connected to the outlet of the membrane bioreactor, and the ecologically stable sedimentation unit is provided with a packing layer for phosphorus removal.

[0010] Preferably, it further includes a backwashing unit; the inlet of the backwashing unit is connected to the outlet of the membrane bioreactor or the outlet of the ecological stabilization sedimentation unit, and is used to backwash the magnetic separator and / or the activated carbon quenching tank.

[0011] Preferably, the system further includes a control system, which is electrically connected to the hydrogen peroxide solution concentration detector inside the alcohol-based hydrogen peroxide in-situ generation unit, the hydrogen peroxide metering pump at the outlet of the unit, the acid metering pump on the acid dosing pipeline, the pressure gauge of the magnetic catalytic photo-Fenton reactor, and the flow control valve on the aeration pipeline of the membrane bioreactor. The control system is used to control the flow rate of the hydrogen peroxide metering pump according to the signal from the concentration detector, control the flow rate of the acid metering pump according to the set pH value, control the pressure of the magnetic catalytic photo-Fenton reactor according to the signal from the pressure gauge, and control the opening degree of the flow control valve according to the set dissolved oxygen concentration.

[0012] This invention also provides a purification method for the above-mentioned self-supplied H2O2 magnetic catalytic enhanced MBR water purification system, comprising the following steps: In the in-situ hydrogen peroxide generation unit, hydrogen peroxide is generated in situ using alcohol waste liquid and air as raw materials without the need for an external power source. The generated hydrogen peroxide is then transported to a tubular mixer. Raw water is also transported to the tubular mixer. A magnetic photocatalyst is added to the tubular mixer to rapidly mix the raw water, hydrogen peroxide, and magnetic photocatalyst, and the pH is adjusted to 3-4. The mixed reaction solution is fed into a magnetic catalytic photo-Fenton reactor and subjected to photo-Fenton oxidation under light conditions to degrade algae, algal toxins and organic pollutants. The effluent after the reaction is sent to a magnetic separator, where a high-gradient magnetic field captures and recovers the magnetic photocatalyst. The recovered catalyst is returned to the catalyst supply pipeline for recycling via a catalyst reuse pipeline. The magnetically separated liquid is then sent to an activated carbon quenching tank to decompose residual hydrogen peroxide. The quenched effluent is then sent to a membrane bioreactor for biological nitrogen and phosphorus removal treatment to obtain purified water.

[0013] Preferably, a high gradient magnetic field of 0.5 to 0.6 T is formed inside the magnetic separator, and the residence time of the water flow in the magnetic separator is 10 to 15 seconds.

[0014] Preferably, the activated carbon quenching tank is filled with granular activated carbon, and the empty bed contact time is 5 to 10 minutes.

[0015] Preferably, the mixing time of the mixture in the tubular mixer is less than 3 seconds.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention uses alcohol waste liquid and air as raw materials to generate hydrogen peroxide in situ under conditions where no external voltage is required and the system relies solely on its own potential difference. Hydrogen peroxide is then coupled with a magnetic visible light catalyst to construct a highly efficient photo-Fenton oxidation system, achieving rapid removal of algae, algal toxins, and organic micropollutants. Simultaneously, a subsequent enhanced MBR and ecological stabilization unit achieve deep removal of nutrients such as nitrogen and phosphorus, thus forming a continuous water purification system that integrates in-situ agent production, advanced oxidation, catalyst recycling, safe quenching, and deep biological purification. Compared with existing technologies, this invention completely eliminates the dependence on purchased oxidants, and eliminates the need for storage, transportation, and addition of ozone, sodium hypochlorite, or hydrogen peroxide, thus eliminating the safety risks of hazardous chemicals. It does not require connection to a high-voltage power grid, relying solely on the self-generating potential difference between waste alcohol and air to drive the reaction, resulting in low energy consumption and off-grid operation, solving the problem of weak power grids in remote areas that hinder its widespread adoption. The use of a magnetic catalyst with high-gradient magnetic separation and recovery achieves a high catalyst recovery rate, allowing for recycling and preventing secondary pollution from iron sludge. The invention thoroughly decomposes residual hydrogen peroxide through an activated carbon quenching unit, ensuring that subsequent biological units are not inhibited and guaranteeing long-term stable system operation. Front-end photo-magnetic Fenton oxidation achieves rapid algae killing and algal toxin degradation, while back-end MBR and ecological precipitation achieve deep nitrogen and phosphorus removal, combining emergency algae control with long-term purification functions. Simultaneously, it uses waste alcohol as a raw material to treat waste with waste, transforming industrial wastewater into an effective resource. The device of this invention has a high degree of integration, requires no hazardous chemical storage and transportation, does not rely on the power grid, and causes no secondary pollution. It is especially suitable for off-grid or weak grid scenarios such as reservoirs, lakeside areas, aquaculture ponds, landscape water bodies, and distributed water supply or reuse in villages and towns. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of the self-supplied H2O2 magnetic catalytic enhanced MBR water purification system according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the magnetic separator in the self-supplied H2O2 magnetic catalytic enhanced MBR water purification system according to an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Raw water booster pump; 2. Primary filtration unit; 3. Tubular mixer; 4. Magnetocatalytic photo-Fenton reactor; 5. Magnetic separator; 6. Activated carbon quenching tank; 7. Magnetic recovery processing tank; 8. Catalyst dosing pump; 9. Membrane bioreactor; 10. Ecologically stable sedimentation unit; 11. Backwashing unit; 12. Acid dosing pipeline; 13. Concentration detector; 14. Aeration device; 15. In-situ alcohol-based hydrogen peroxide generation unit; 16. Pressure gauge; 17. Water distribution plate. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described objects changes, the relative positional relationship may also change accordingly.

[0022] This invention provides a self-supplying H2O2 magnetically enhanced MBR water purification system, comprising a raw water supply pipeline, an in-situ alcohol-based hydrogen peroxide generation unit 15, a catalyst supply pipeline, a tubular mixer 3, a magnetically catalytic photo-Fenton reactor 4, a magnetic separator 5, an activated carbon quenching tank 6, a membrane bioreactor 9, and a catalyst recycling pipeline; the raw water supply pipeline or the outlet pipeline of the in-situ alcohol-based hydrogen peroxide generation unit 15 is also connected to an acid dosing pipeline, such as... Figure 1 As shown, the acid dosing pipeline is connected to the outlet pipeline of the alcohol-based hydrogen peroxide in-situ generation unit 15. The outlet pipelines of the raw water supply pipeline, the alcohol-based hydrogen peroxide in-situ generation unit 15, and the catalyst supply pipeline are all connected to the tubular mixer 3 to mix the raw water, hydrogen peroxide, acid, and magnetic photocatalyst. The outlet of the tubular mixer 3 is sequentially connected to the magnetic catalytic photo-Fenton reactor 4, the magnetic separator 5, the activated carbon quencher 6, and the membrane bioreactor 9. The magnetic separator 5 is connected to the catalyst supply pipeline via the catalyst recycling pipeline. The alcohol-based hydrogen peroxide in-situ generation unit 15 includes an anode chamber, a cathode chamber, an ion exchange membrane disposed between the anode chamber and the cathode chamber, an anode, and a cathode. The anode chamber is connected to an alcohol waste liquid source, and the cathode chamber is connected to an air source. The anode and cathode are connected via an external circuit to generate hydrogen peroxide in-situ using an anodic oxidation reaction and a cathode two-electron reduction reaction without the need for an external power supply.

[0023] like Figure 1 As shown, in this embodiment, the raw water supply pipeline is connected to the raw water lift pump 1. The raw water lift pump 1 lifts the raw water to be treated (from reservoirs, ponds, aquaculture ponds, etc.) from a low point to the working pressure required by the system, providing the necessary water flow power for subsequent treatment units. Preferably, the raw water lift pump 1 is also connected to a pre-filtration unit 2 for preliminary filtration of the raw water. The pre-filtration unit 2 mainly uses a filter, such as a filter screen. It traps and removes large particulate matter, fibers, large algae, leaves, and other impurities from the raw water. Its core function is to protect downstream precision equipment and units, preventing the raw water lift pump 1, pipelines, valves, reactors, and membrane modules from clogging or wear. After preliminary filtration and removal of large particulate impurities, the raw water becomes relatively uniform, creating stable conditions for subsequent precise chemical dosing and efficient reactions. This portion of water is then stably transported to the next unit.

[0024] The alcohol-based hydrogen peroxide in-situ generation unit 15 uses alcohol waste liquid as fuel and air as oxidant to generate hydrogen peroxide in situ under the coupling effect of anodic oxidation and cathode two-electron reduction reaction. In this embodiment, ethylene glycol waste liquid is preferably used as raw material, and continuous production is achieved under zero applied voltage conditions through membrane electrode assembly. The generated hydrogen peroxide solution is introduced into the raw water main pipeline after concentration detection and metering, replacing the transportation and storage of traditional purchased hydrogen peroxide.

[0025] More specifically, such as Figure 1 As shown, the in-situ hydrogen peroxide generator stack of this embodiment uses ethylene glycol waste liquid as fuel and air as oxidant. An aeration device 14 is added to the hydrogen peroxide cathode chamber to increase the yield. In this membrane electrode assembly, a spontaneous chemical reaction coupled with zero external pressure technology occurs. Ethylene glycol is oxidized on the anode catalyst (e.g., 5% PtNiCu / C), releasing electrons. These electrons spontaneously flow to the cathode through an external circuit. Oxygen receives electrons on the cathode gas diffusion electrode (e.g., OCNT / GDE), undergoing a two-electron reduction reaction to generate H2O2. This is then fed in parallel with a KOH electrolyte that is available at room temperature and pressure, with air readily available. The generated H2O2 solution is precisely metered by a dosing pump and a concentration detector and injected into the main raw water pipeline. This unit completely replaces the need for purchasing, transporting, and storing hazardous concentrated hydrogen peroxide. The main principle utilized is the spontaneous chemical potential difference between the anode and cathode driving electron flow, achieving zero external voltage H2O2 generation without an external power supply. The specific reaction equation is as follows:

[0026] Anode reaction: ; Cathode reaction: ; The generated H2O2 solution is pumped into the main raw water pipeline. In a more preferred method, acid, such as sulfuric acid, can be automatically added under PLC control and instantaneously and thoroughly mixed in tubular mixer 3 to quickly and accurately adjust the pH of the water to a predetermined range. The main purpose is to adjust the self-produced H2O2 solution (containing KOH electrolyte) to a weakly acidic condition to achieve the best effect for the subsequent photo-Fenton reaction. The pH-adjusted raw water containing H2O2 is then transported to the core reaction unit, the magnetic catalytic photo-Fenton reactor 4. In this embodiment, the magnetic catalytic photo-Fenton reactor 4 is the core oxidative degradation unit. Under light conditions and in the presence of hydrogen peroxide, the magnetic photocatalyst absorbs light energy and excites electron-hole pairs, promoting the oxidation and degradation of Fe³⁺. + / Fe² + The process involves cycling and generating hydroxyl radicals, thereby achieving efficient oxidative degradation of algal cell structures, algal toxin molecules, and recalcitrant organic micropollutants. Preferably, the magnetic photocatalyst is a g-C3N4 / Fe3O4 composite magnetic catalyst.

[0027] See again Figure 1 The visible light-driven magnetic catalytic photo-Fenton reactor 4 is the core battleground for killing algae, degrading algal toxins, and organic pollutants. A magnetic g-C3N4 / Fe3O4 composite catalyst is pre-added to the tubular mixer 3 via a dosing pump. A flow equalization plate is arranged in the magnetic catalytic photo-Fenton reactor 4 to evenly distribute the incoming water throughout the entire treatment cross-section. A pressure gauge is placed in the reactor 4; this pressure gauge is a core monitoring device ensuring the safe operation of the reactor. By monitoring the internal pressure in real time, it prevents equipment overpressure rupture, diagnoses pipeline blockage or leakage, and indirectly reflects the intensity of the reaction process, providing crucial data support for the safe, stable, and efficient operation of the system. Furthermore, the catalyst is added to the tubular mixer 3 before the reactor via a catalyst dosing pump 8, achieving instantaneous and uniform mixing of the catalyst and reactants. This eliminates reaction delays, prevents catalyst sedimentation and caking, and allows for flexible adjustment of the dosing amount based on water quality and quantity, thereby maximizing reaction efficiency and simplifying reactor design. Most importantly, under visible light (LED or UV) irradiation and in the presence of H2O2, g-C3N4 absorbs visible light to generate electron-hole pairs, and the holes and H2O2 directly produce ·OH; simultaneously, photogenerated electrons propel Fe... 3+ Reduced to Fe 2+ Fe 2+It undergoes a classic Fenton reaction with H₂O₂ to efficiently generate ·OH, initiating a highly efficient photo-Fenton reaction. This process non-selectively and strongly oxidizes and destroys algal cell structure, photosynthetic system, metabolic enzymes, and genetic material, while simultaneously and thoroughly degrading algal toxins. It effectively kills algae and bacteria in high-algae water, landscape water, aquaculture water, and swimming pool water. It can also degrade micro-pollutants such as antibiotics and dyes. The oxidized water, carrying the suspended magnetic catalyst, flows into the next separation unit.

[0028] The main classical Fenton reactions used are as follows: .

[0029] The magnetic separation and recovery unit in this embodiment is used to perform solid-liquid separation on the effluent after oxidation reaction. Magnetic catalyst particles in the water are captured by a high-gradient magnetic field. In a preferred manner, the recovered catalyst is first transported to a catalyst recovery and processing tank. After regeneration or blending in the catalyst recovery and processing tank, it is returned to the front-end reaction unit by the catalyst dosing pump 8 for recycling, thereby realizing a closed-loop catalyst circulation, reducing operating costs and secondary solid waste generation.

[0030] In this embodiment, the magnetic separator 5 is a high-gradient magnetic separator, which generates a high-intensity gradient magnetic field internally. When water flows through it, micron-sized magnetic catalyst particles are strongly captured by the magnetic field and adsorbed onto the magnetic roller, such as... Figure 2 As shown, the catalyst is scraped back into the magnetic recovery processing tank 7 and can be reused in the system via the catalyst addition pump 8. The magnetic separator 5 adsorbs and recovers almost all of the magnetic g-C3N4 / Fe3O4 catalyst suspended in the effluent, realizing solid-liquid separation and recycling of the catalyst and water, forming a closed-loop material system.

[0031] In this embodiment, the activated carbon quenching tank 6 is located at the rear end of the magnetic separation and recovery unit. Utilizing the abundant functional groups and large specific surface area of ​​activated carbon, the activated carbon quenching tank 6 can efficiently catalyze the decomposition of H2O2 into water and oxygen, while simultaneously physically adsorbing dissolved organic matter. It serves as a safety barrier for the entire process, thoroughly decomposing and adsorbing any trace amounts of H2O2 and incompletely oxidized small-molecule organic matter that may remain after the preceding reactions, ensuring that the effluent is free of any oxidant residue, thus guaranteeing the safety of subsequent biological units and the final water supply.

[0032] In this embodiment, the membrane bioreactor 9 is an enhanced algae-bacterial symbiotic MBR, used to remove nutrients such as nitrogen (ammonia nitrogen, nitrate) and phosphorus that are difficult to degrade effectively in the previous oxidation unit, achieving deep water purification and ecological stabilization, and ensuring that the effluent meets high standards for reuse or discharge. Based on the principles of nitrification-denitrification biological nitrogen removal and adsorption sedimentation + bioaccumulation phosphorus removal, the synergistic effect of algae and bacteria improves treatment efficiency and reduces operating costs. Nitrification occurs primarily in the aerobic zone, converting ammonia nitrogen into nitrate. Denitrification mainly occurs in the anoxic zone, converting nitrate into nitrogen gas for nitrogen removal. Phosphorus removal is achieved in the sedimentation zone through the adsorption and sedimentation of the packing material. The effluent is the final product water, which can be reused for landscaping, irrigation, aquaculture, or directly discharged. Part of the effluent can be used for system backwashing, serving as the water source for the backwashing unit 11, realizing internal water resource circulation.

[0033] As another preferred embodiment, it also includes an ecologically stable sedimentation unit 10, the inlet of which is connected to the outlet of the membrane bioreactor, and the ecologically stable sedimentation unit is provided with a packing layer for phosphorus removal.

[0034] In another preferred embodiment, a control system is also included. This control system is connected to the concentration detector 13, acid dosing line 12, pressure gauge 16, aeration device 14, catalyst dosing pump 8, hydrogen peroxide metering pump, and backwashing unit 11, respectively. It is used to coordinate and regulate each unit based on influent water quality, reaction status, and operating parameters. The control system primarily uses H2O2 concentration, pH, pressure, flow rate, and DO as inputs, employing feedforward, PID control, and interlocking to automatically adjust the production agent, acid addition, aeration, backwashing, and flow rate. This ensures full matching between photo-Fenton, magnetic separation, and MBR processes, achieving stable effluent, energy saving, and safe operation.

[0035] In a preferred embodiment, the magnetic separator 5 includes a magnetic rotating shaft and a scraper. The magnetic rotating shaft is used to adsorb magnetic photocatalysts under a high gradient magnetic field, and the scraper is attached to the surface of the magnetic rotating shaft to scrape out the adsorbed catalyst and export it to the catalyst recycling pipeline.

[0036] Based on the same inventive concept, the present invention also provides a purification method for the above-mentioned self-supplied H2O2 magnetic catalytic enhanced MBR water purification system, comprising the following steps: In the in-situ hydrogen peroxide generation unit 15, hydrogen peroxide is generated in situ using alcohol waste liquid and air as raw materials without the need for an external power source. The generated hydrogen peroxide is then transported to the tubular mixer 3. Raw water is also transported to the tubular mixer 3. A magnetic photocatalyst is added to the tubular mixer 3 to rapidly mix the raw water, hydrogen peroxide, and magnetic photocatalyst in the tubular mixer 3, and the pH is adjusted to 3-4. The mixed reaction solution is fed into the magnetic catalytic photo-Fenton reactor 4, where a photo-Fenton oxidation reaction is carried out under light conditions to degrade algae, algal toxins and organic pollutants. The effluent after the reaction is sent to magnetic separator 5, where the magnetic photocatalyst is captured and recovered by a high gradient magnetic field. The recovered catalyst is returned to the catalyst supply pipeline for recycling via the catalyst reuse pipeline. The liquid after magnetic separation is sent to activated carbon quenching tank 6 to decompose residual hydrogen peroxide. The quenched effluent is then sent to membrane bioreactor 9 for biological denitrification and phosphorus removal to obtain purified water.

[0037] Example Taking the treatment of centralized water supply and wastewater reuse in rural areas as a case study, the influent water quality (typical algae-rich water body) is as follows: COD: 120 mg / L, NH3-N: 8 mg / L, TN: 20 mg / L, TP: 2.5 mg / L, pH: 7.0-8.5, algae density: >10 7 cells / L; The in-situ alcohol-based hydrogen peroxide generation unit in this embodiment adopts a membrane electrode assembly structure. Ethylene glycol waste liquid is introduced into the anode chamber, and air is introduced into the cathode chamber. The anode is a 5% PtNiCu / C catalyst-supported anode, and the cathode is OCNT / GDE carbon nanotubes. The gas diffusion electrode generates electricity automatically. Operating conditions: short-circuit current ≈ 40 mA / cm². -2 In this embodiment, the in-situ hydrogen peroxide generation unit uses an alkaline electrolyte KOH solution, which can operate stably under normal temperature and pressure conditions. Air can be directly introduced into the cathode as an oxygen source, eliminating the need for pure oxygen. When it is necessary to increase the hydrogen peroxide production, multiple generation units can be used in parallel to meet the treatment needs of water bodies of different sizes. Based on the H2O2 production, the required ethylene glycol is approximately 2.0~2.2 kg / h (by mass ratio ethylene glycol:H2O2≈1.2:1), and the air is approximately 16 Nm³ / h (by volume ratio air:H2O2≈9:1). This ensures that the H2O2 concentration required for the photo-Fenton reaction remains stable within the optimal range of 30~40 mg / L. This concentration is mainly determined by the photo-Fenton stoichiometry, the energy efficiency of the in-situ product, and catalyst matching. More specifically, a mass ratio of ethylene glycol to H₂O₂ of 1.2:1 and a volume ratio of air to H₂O₂ of 9:1 can match the electron-donating rate of ethylene glycol oxidation at the anode with the two-electron reduction rate of oxygen at the cathode, thus maintaining a stable in-situ H₂O₂ concentration of 30–40 mg / L. Insufficient ethylene glycol supply leads to insufficient electron supply and a decrease in H₂O₂ yield; excessive ethylene glycol results in unconverted alcohols increasing COD load and competing for ·OH. Insufficient air supply limits the cathode oxygen reduction reaction; excessive air reduces gas utilization and increases aeration energy consumption.

[0038] After the self-produced hydrogen peroxide solution is mixed with raw water, dilute sulfuric acid (concentration of 10-20% H2SO4) is automatically added under PLC control at a dosage of 150-200 mg / L (flow rate of 10-12 L / h when preparing a 10% solution). The mixture after addition enters a composite catalytic tubular mixer, with a mixing time of less than 3 seconds, to quickly adjust the pH of the system to 3-4. In this embodiment, the purpose of a mixing time of less than 3 seconds is to avoid premature consumption of H2O2 before entering the photo-Fenton reactor and to reduce local pH fluctuations and catalyst agglomeration. In this embodiment, the system pH is 3-4, which is beneficial for maintaining Fe²⁺. + / Fe³ + Cyclic activity is improved to enhance the conversion efficiency of H2O2 to ·OH. Below pH 3.0, H2O2 stability increases and acid consumption rises, leading to a decrease in ·OH formation efficiency. Above pH 4.0, iron species are prone to hydrolysis or surface passivation, resulting in a reduced photo-Fenton reaction rate. The flow rate of the metering pump used for adding dilute sulfuric acid should be 0-15 L / h, requiring an acid-resistant and corrosion-resistant pump.

[0039] At the front end of the composite catalytic tubular mixer, a g-C3N4 / Fe3O4 composite magnetic catalyst is added to the mixer via a catalyst dosing pump. The catalyst concentration range is 230~250 mg / L, which provides sufficient photocatalytic active sites and Fe²⁺. + / Fe³ + The circulating sites enable efficient conversion of H2O2 to ·OH. When the catalyst concentration is below 230 mg / L, there are insufficient active sites, resulting in reduced H2O2 activation efficiency and organic pollutant oxidation rate. When the catalyst concentration is above 250 mg / L, the suspended particle concentration is too high, easily causing light shielding and particle agglomeration, reducing light utilization efficiency, and increasing the load on magnetic separation and catalyst recovery. The minimum residence time in the tubular mixer 3 of the subsequent mixed liquid entering the magnetic catalytic photo-Fenton reactor is 6-10 minutes. Before the reactor, the catalyst is added to the tubular mixer 3 by a dosing pump, which can achieve instantaneous and uniform mixing of the catalyst and reactants, eliminate reaction delay, prevent catalyst sedimentation and caking, and flexibly adjust the dosage according to water quality and quantity, thereby maximizing reaction efficiency and simplifying reactor design. In addition, the effective volume of the magnetic catalytic photo-Fenton reactor should not be less than 0.5 m³. The light source in the reactor can be a high-power LED or UV for continuous irradiation. Under visible light irradiation, Fe²⁺ in the catalyst undergoes a Fenton reaction with H2O2 to generate hydroxyl radicals, while photogenerated electrons convert Fe²⁺ into ·OH. + Reduced to Fe² + This achieves a photo-Fenton cycle reaction. The reactor is equipped with a water distribution plate to ensure uniform dispersion of the incoming water, and a pressure gauge monitors real-time pressure changes within the reactor to ensure safe operation.

[0040] The effluent from the photo-Fenton reaction enters a high-gradient magnetic separator. A high-gradient magnetic field of 0.5–0.6T is formed inside the separator, using magnetic rollers as the high-gradient magnetic trapping component. The residence time of the water flow in the magnetic separator is 10–15 seconds. Micron-sized magnetic catalyst particles are captured by the magnetic field and desorbed from the surface of the magnetic rollers by a scraper mechanism, then recovered to a catalyst recovery and processing tank. The catalyst recovery rate reaches 99.5%. After regeneration, the recovered catalyst is returned to the front end of the composite catalytic tubular mixer for recycling via a catalyst dosing pump.

[0041] In this embodiment, the magnetic field strength is 0.5–0.6 T, and the hydraulic residence time is 10–15 s. Under these conditions, the micron-sized g-C3N4 / Fe3O4 composite magnetic catalyst can obtain sufficient magnetic trapping force and migration time within the magnetic field region, thereby achieving efficient solid-liquid separation and catalyst recycling. When the magnetic field strength is below 0.5 T or the residence time is less than 10 s, the catalyst capture is insufficient, which can easily lead to catalyst loss and contamination of subsequent units. When the magnetic field strength is above 0.6 T or the residence time is longer than 15 s, the recovery efficiency improvement is limited, but the equipment cost, magnetic roller desorption resistance, floor space, and hydraulic losses increase.

[0042] The liquid phase after magnetic separation enters activated carbon adsorption tank 6, which is filled with coal-based columnar activated carbon with an iodine value greater than 900 mg / g to facilitate the adsorption of excess H2O2. The remaining H2O2 is in contact with the empty bed of activated carbon quenching tank 6 for 5–10 minutes (effective contact volume 0.35–0.5 m³) to catalyze the decomposition of residual hydrogen peroxide and adsorb residual organic matter after oxidation. These parameters are designed to ensure complete quenching of the remaining H2O2.

[0043] In this embodiment, the contact time between the remaining H2O2 and the empty bed of the activated carbon quenching tank 6 is 5-10 minutes. This time range allows the residual H2O2 to be fully catalytically decomposed into water and oxygen on the activated carbon surface, while simultaneously adsorbing small molecule organic matter remaining after the initial oxidation. When the empty bed contact time is less than 5 minutes, the residual H2O2 decomposes incompletely, which may inhibit the activity of nitrifying bacteria, denitrifying bacteria, and algae-bacteria symbiotic system in the subsequent MBR. When the empty bed contact time is more than 10 minutes, the improvement in H2O2 removal tends to be limited, but it will increase the equipment volume, head loss, and activated carbon consumption, and may excessively reduce the available carbon source required for subsequent denitrification.

[0044] After activated carbon quenching, the effluent sequentially enters the enhanced MBR unit and the ecologically stable sedimentation unit. The total hydraulic retention time is 1.5–2.5 h, and the total effective volume is 10–12 m³. Specifically, the hydraulic retention time in the high-contact oxidation zone of the enhanced MBR unit is 1–1.2 h, with an effective volume of 5–6 m³, an air-to-water ratio of 12:1, and an air supply of 55–60 Nm³ / h. The hydraulic retention time in the ecologically stable sedimentation zone is 0.8–1.5 h, with an effective volume of 4–6 m³, and it contains a packing layer for phosphorus removal. Deep purification is achieved through the synergistic effects of biological denitrification, membrane separation, and adsorption sedimentation. Using the above design in this embodiment, the effluent is the final product water, meeting direct discharge standards, and can also be reused within the system.

[0045] The system is equipped with a backwashing unit, which is connected to the effluent of the enhanced MBR unit and / or the ecological stabilization sedimentation unit. It uses partially treated effluent to backwash the magnetic separator, activated carbon adsorption tank, and / or the enhanced MBR unit. The control system is electrically connected to the concentration detector, the acid dosing line of the pH adjustment unit, the pressure gauge of the magnetic catalytic photoreactor, the aeration device of the enhanced MBR unit, and the backwashing unit. Based on sensor signals, it dynamically adjusts the hydrogen peroxide dosage, acid dosage, reaction pressure, aeration intensity, and backwashing cycle.

[0046] The effluent quality standards after treatment are as follows: COD: <30mg / L, NH3-N: <1.5mg / L, TN: <10mg / L, TP: <0.2mg / L, pH: 6.5-8.5, and algal density / algal toxins are undetectable.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-supplied H2O2 magnetic catalytic enhanced MBR water purification system, characterized in that, The system includes a raw water supply pipeline, an in-situ alcohol-based hydrogen peroxide generation unit, a catalyst supply pipeline, a tubular mixer, a magnetic catalytic photo-Fenton reactor, a magnetic separator, an activated carbon quenching tank, a membrane bioreactor, and a catalyst recycling pipeline. An acid dosing pipeline is also connected to the outlet pipeline of the raw water supply pipeline or the outlet pipeline of the in-situ alcohol-based hydrogen peroxide generation unit. The outlet pipelines of the raw water supply pipeline, the in-situ alcohol-based hydrogen peroxide generation unit, and the catalyst supply pipeline are all connected to the tubular mixer to mix raw water, hydrogen peroxide, acid, and the magnetic photocatalyst. The outlet of the tubular mixer is sequentially connected to the magnetic catalytic photo-Fenton reactor, the magnetic separator, the activated carbon quenching tank, and the membrane bioreactor. The magnetic separator is connected to the catalyst supply pipeline via the catalyst recycling pipeline. The in-situ hydrogen peroxide generation unit includes an anode chamber, a cathode chamber, an ion exchange membrane disposed between the anode chamber and the cathode chamber, an anode, and a cathode. The anode chamber is connected to an alcohol waste liquid source, and the cathode chamber is connected to an air source. The anode and cathode are connected via an external circuit to generate hydrogen peroxide in situ using an anodic oxidation reaction and a cathode two-electron reduction reaction without the need for an external power supply.

2. The self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1, characterized in that, The alcohol waste liquid is ethylene glycol waste liquid; the anode is an anode supported on a PtNiCu / C catalyst, and the cathode is a gas diffusion cathode; the cathode chamber is equipped with an aeration device.

3. The self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1, characterized in that, The magnetic separator includes a magnetic rotating shaft and a scraper. The magnetic rotating shaft is used to adsorb magnetic photocatalysts under a high gradient magnetic field. The scraper is attached to the surface of the magnetic rotating shaft and is used to scrape out the adsorbed catalyst and export it to the catalyst recycling pipeline.

4. The self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1, characterized in that, It also includes an ecologically stable sedimentation unit, the inlet of which is connected to the outlet of the membrane bioreactor, and the ecologically stable sedimentation unit is provided with a packing layer for phosphorus removal.

5. The self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1 or 4, characterized in that, It also includes a backwashing unit; the inlet of the backwashing unit is connected to the outlet of the membrane bioreactor or the outlet of the ecological stabilization sedimentation unit, and is used to backwash the magnetic separator and / or the activated carbon quenching tank.

6. The self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1, characterized in that, It also includes a control system, which is electrically connected to the hydrogen peroxide solution concentration detector inside the alcohol-based hydrogen peroxide in-situ generation unit, the hydrogen peroxide metering pump at the outlet of the unit, the acid metering pump on the acid dosing pipeline, the pressure gauge of the magnetic catalytic photo-Fenton reactor, and the flow control valve on the aeration pipeline of the membrane bioreactor. The control system is used to control the flow rate of the hydrogen peroxide metering pump according to the signal from the concentration detector, control the flow rate of the acid metering pump according to the set pH value, control the pressure of the magnetic catalytic photo-Fenton reactor according to the signal from the pressure gauge, and control the opening degree of the flow control valve according to the set dissolved oxygen concentration.

7. The purification method of the self-supplied H2O2 magnetic catalytic enhanced MBR water purification system as described in claim 1, characterized in that, Includes the following steps: In the in-situ hydrogen peroxide generation unit, hydrogen peroxide is generated in situ using alcohol waste liquid and air as raw materials without the need for an external power source. The generated hydrogen peroxide is then transported to a tubular mixer. Raw water is also transported to the tubular mixer. A magnetic photocatalyst is added to the tubular mixer to rapidly mix the raw water, hydrogen peroxide, and magnetic photocatalyst, and the pH is adjusted to 3-4. The mixed reaction solution was fed into a magnetic catalytic photo-Fenton reactor to carry out photo-Fenton oxidation under light irradiation. The effluent after the reaction is sent to a magnetic separator, where a high-gradient magnetic field captures and recovers the magnetic photocatalyst. The recovered catalyst is returned to the catalyst supply pipeline for recycling via a catalyst reuse pipeline. The magnetically separated liquid is then sent to an activated carbon quenching tank to decompose residual hydrogen peroxide. The quenched effluent is then sent to a membrane bioreactor for biological nitrogen and phosphorus removal treatment to obtain purified water.

8. The method for purifying waste alcohol gas and water from a magnetically catalytically enhanced MBR process as described in claim 7, characterized in that, A high gradient magnetic field of 0.5 to 0.6 T is formed inside the magnetic separator, and the residence time of the water flow in the magnetic separator is 10 to 15 seconds.

9. The method for purifying waste alcohol gas and water from a magnetically catalytically enhanced MBR process as described in claim 7, characterized in that, The activated carbon quenching tank is filled with granular activated carbon, and the empty bed contact time is 5 to 10 minutes.

10. The method for purifying waste alcohol gas and water from a magnetically catalytically enhanced MBR process as described in claim 7, characterized in that, The mixing time of the mixture in the tubular mixer is less than 3 seconds.

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