A sewage treatment device and method based on membrane filament oxygen supply and electrode synergistic effect of iron redox conversion

Abstract

The application discloses a sewage treatment device and method based on membrane filament oxygen supply and electrode synergistic effect of iron redox conversion, the device comprises a reactor, an electrode unit, an oxygen supply membrane unit, an iron base unit, a separation unit and a gas supply system. The oxygen supply membrane and the iron base unit are alternately arranged at a micro distance of 0.5-5 mm to form an iron-oxygen alternating interface; the electrode unit and the oxygen supply membrane unit are separated by the separation unit to form redox subareas. The application utilizes the migration and conversion of iron ions between aerobic and anaerobic zones to construct a non-contact electron transfer path, realizes simultaneous nitrification, denitrification and chemical phosphorus removal; the micro distance iron-oxygen interface can limit the initiation of efficient electro-Fenton reaction to produce hydroxyl radicals and strengthen the degradation of difficult-to-degrade organic matters such as pyrethroid. The application integrates biological denitrification, chemical phosphorus removal, advanced oxidation and biological electricity generation functions, has the advantages of high treatment efficiency, low energy consumption, stable operation and the like, and is especially suitable for treating industrial wastewater containing difficult-to-degrade organic matters.

Description

Technical Field

[0001] This invention relates to the field of water treatment and environmental engineering technology, specifically to a wastewater treatment device and method based on iron redox conversion, which combines membrane fiber oxygen supply with electrode synergy. It is particularly suitable for treating industrial wastewater containing recalcitrant organic matter (such as pyrethroid pesticides, halogenated aromatic hydrocarbons, etc.), municipal wastewater with an imbalanced carbon-nitrogen ratio, and aquaculture wastewater with high nitrogen and phosphorus content. Background Technology

[0002] With increasingly stringent wastewater treatment and discharge standards and the advancement of the "dual carbon" target, the development of efficient, low-consumption, and resource-efficient wastewater treatment technologies has become an urgent need for the industry. Membrane-aerated biofilm reactors (MABRs), as a novel aerobic biological treatment technology, utilize hollow fiber membranes for bubble-free oxygen supply, offering advantages such as high oxygen utilization (theoretically up to 100%), low energy consumption, and small footprint. MABRs create an oxygen concentration gradient inside and outside the membrane fibers, enabling simultaneous nitrification and denitrification (SND) within a single reactor, attracting widespread attention.

[0003] However, traditional MABR technology still faces several core bottlenecks when treating complex wastewater: (1) Carbon source dependence and limited denitrification: For municipal sewage or industrial wastewater with a low carbon-to-nitrogen ratio (C / N), the denitrification process is severely inhibited due to the lack of sufficient electron donors (organic carbon sources), resulting in nitrate accumulation and low total nitrogen (TN) removal rate. (2) Lack of phosphorus removal capacity: The MABR system is essentially a biofilm system, lacking an effective phosphorus removal mechanism. The removal of phosphorus mainly relies on microbial assimilation, which has extremely low removal efficiency. It usually requires a subsequent chemical phosphorus removal unit, which increases operating costs and operational complexity. (3) Insufficient capacity to treat recalcitrant organic matter: When treating industrial wastewater containing recalcitrant organic matter such as pyrethroid pesticides, antibiotics, and halogenated aromatic hydrocarbons, these substances have inhibitory or toxic effects on microorganisms, and their stable chemical structure is difficult to be destroyed by conventional biological metabolic pathways, resulting in low removal rate and exacerbating membrane fouling. (4) Membrane fouling and material stability issues: Hydrophobic pollutants and extracellular polymers (EPS) produced by microbial metabolism in wastewater are easily adsorbed and accumulated on the membrane surface, leading to membrane pore blockage and thickening of the fouling layer, which increases mass transfer resistance. In addition, organic solvents in some industrial wastewater can cause swelling or dissolution of polymer membrane materials (such as polyvinylidene fluoride, polypropylene, etc.), shortening the life of membrane modules.

[0004] Bioelectrochemical systems (BES) utilize the extracellular electron transfer characteristics of electroactive microorganisms to oxidize organic matter and generate electrons under anaerobic conditions. These electrons can be transferred to the cathode via an external circuit, driving reduction reactions (such as nitrate reduction and oxygen reduction). Theoretically, coupling BES with a microbial bioreactor (MABR) could provide electrons for denitrification through electrode processes, compensating for insufficient carbon sources, and potentially pretreating recalcitrant organic matter through cathode reduction. However, existing coupling technologies (such as MABR-microbial fuel cells) still have drawbacks: low cathode oxygen reduction efficiency, a single electron transfer pathway within the system (mainly relying on the external circuit), and a lack of spatial optimization for key functional materials such as iron, making it difficult to form an efficient microscopic reaction interface.

[0005] Iron is one of the most abundant redox reactive metal elements in the environment, and its valence state cycle (Fe) 2+ ⇌Fe 3+ It can couple multiple biochemical processes. Fe 2+ It can act as an electron donor to drive denitrification (i.e., iron autotrophic denitrification), while Fe 3+ It can act as an electron acceptor in the mineralization of organic matter. Simultaneously, iron (hydride) oxides have a strong affinity for phosphates, making them excellent chemical phosphorus removal agents. Furthermore, Fe... 2+ Iron can react with hydrogen peroxide to form Fenton's reagent, generating highly oxidizing hydroxyl radicals (·OH), which can efficiently and non-selectively degrade recalcitrant organic compounds. However, how to spatially couple the membrane oxygen supply, electrode reaction, and iron-based materials in the MABR-BES system to leverage the aforementioned multiple synergistic effects of iron cycling, while avoiding passivation or membrane fouling caused by indiscriminate deposition of iron oxides, remains an unsolved problem in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing MABR and MABR-BES coupled technologies in nitrogen and phosphorus removal, removal of recalcitrant organic matter, and operational stability, and to provide a wastewater treatment device and method based on iron redox conversion through membrane fiber oxygen supply and electrode synergy. This invention utilizes iron ions (Fe²⁺) by constructing a micro-interface of alternating iron and oxygen and redox spatial partitioning. 2+ / Fe 3+ As an endogenous electron shuttle, it achieves electron transport network reconstruction, simultaneous nitrogen and phosphorus removal, confined electro-Fenton enhanced degradation, and membrane fouling self-inhibition within a single reactor, thereby realizing efficient, stable, and low-consumption wastewater treatment.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a wastewater treatment device based on iron redox conversion, involving membrane fiber oxygen supply and electrode synergy, characterized in that it comprises:

[0009] The reactor, equipped with an inlet and an outlet, is internally divided into at least a low dissolved oxygen reaction zone and a membrane fiber oxygen supply reaction zone. This reactor is used to contain wastewater to be treated and to provide operating space for each functional unit. The positions of the inlet and outlet can be set according to the water flow direction (e.g., plug flow, completely mixed, or upflow).

[0010] The electrode unit, located within the low dissolved oxygen reaction zone, is used to enrich electroactive microorganisms and degrade organic matter. This unit acts as a bioanode; under anaerobic / anoxic conditions, electroactive microorganisms (such as Geobacter and Shewanella) metabolize organic matter in wastewater as a substrate and transfer the electrons generated during metabolism to the surface of the electrode material.

[0011] An oxygen supply membrane unit, disposed within the oxygen supply reaction zone of the membrane filament, includes at least one hollow fiber membrane filament for bubble-free oxygen supply to the oxygen supply reaction zone. The membrane filament wall is oxygen-permeable, and oxygen introduced into the interior, driven by partial pressure, permeates through the membrane wall and dissolves directly into the surrounding liquid phase and biofilm, forming an oxygen concentration gradient that gradually decreases from the membrane filament surface outward (aerobic → anoxic → anaerobic).

[0012] Iron-based units are disposed within the oxygen supply reaction zone of the membrane filaments and are alternately arranged with the oxygen supply membrane units at a spacing of 0.5-5 mm along the spatial direction, forming an alternating iron-oxygen interface reaction zone. This compact micro-spacing arrangement is a key feature of the present invention. In this configuration, oxygen diffused from the surface of the membrane filaments reacts with ferrous ions (Fe2+) released from the surface of the iron-based units. 2+ They meet within a very short distance, forming a highly active chemical / biological reaction interface.

[0013] A separating unit, located between the electrode unit and the oxygen supply membrane unit, maintains the redox separation between the low dissolved oxygen reaction zone and the membrane fiber oxygen supply reaction zone, allowing iron ions to migrate between the two zones. This unit physically divides the reactor into two main environments (anaerobic and aerobic zones), preventing large amounts of oxygen from entering the low dissolved oxygen zone and interfering with anaerobic processes (such as denitrification and iron reduction), while simultaneously ensuring the solubility of Fe. 2+ / Fe 3+ Iron can be recycled by migrating between the two zones through diffusion or water flow.

[0014] An oxygen supply system, connected to the oxygen supply membrane unit, is used to provide oxygen-containing gas (such as air or pure oxygen). This system may include an air pump, buffer tank, filter, pressure gauge, valves, and flow meter to achieve a stable and controllable oxygen supply.

[0015] The fixing unit is used to securely fix the electrode unit, oxygen supply membrane unit and iron-based unit in the reactor to resist hydraulic and gas disturbances and maintain the stability of the interfacial reaction structure.

[0016] The external circuit can selectively connect the electrode unit to the iron-based unit and / or the oxygen supply membrane unit. When connected, a closed loop can be formed, enabling directional electron transfer and energy recovery.

[0017] The monitoring system may include a pH monitor, a temperature monitor, and a dissolved oxygen detector installed in the reactor, each of which is connected to a data collector. The data collector is used to generate control signals based on changes in parameters such as dissolved oxygen concentration to adjust the oxygen supply intensity of the gas supply system and achieve dynamic control of oxygen diffusion flux.

[0018] The core working mechanism and collaborative innovation of the device of this invention lie in:

[0019] (I) Iron cycle-mediated non-contact electron transfer and enhanced denitrification

[0020] The iron-based unit is a filamentous composite structure formed by stranding iron-based alloy wires to form a filamentous skeleton with an outer support structure, and filling the internal voids with iron shavings and porous ceramic particles loaded with nano-sized ferrous oxide. The iron-based unit is not directly electrically connected to the oxygen supply membrane unit; instead, it is connected via Fe... 2+ / Fe 3+ The redox cycle forms a non-contact electron transfer path between the electrode unit and the oxygen supply membrane unit. During operation, in the oxygen supply reaction zone (aerobic zone) of the membrane fibers, oxygen diffuses through the membrane wall, supporting the aerobic biomembrane to oxidize ammonia nitrogen to nitrate nitrogen (nitration); on the other hand, it releases Fe from the iron-based unit and conductive coating. 2+ Rapid chemical oxidation to Fe 3+ And form iron (hydrogen) oxide precipitates to adsorb and remove phosphates. Contains Fe 3+ The mixture of nitrate nitrogen and Fe2+ enters the low dissolved oxygen reaction zone (anaerobic zone) through a separation unit. In the anaerobic zone, electroactive microorganisms on the electrode units utilize organic matter in the wastewater (or utilize electrons from the cathode) to convert Fe2+ into Fe2+. 3+ Reduced to Fe 2+ (Iron reduction). More importantly, the Fe produced by reduction... 2+ It can be used as an inorganic electron donor to convert nitrate nitrogen (NO3) into an inorganic electron donor. - Iron (Fe3+) is reduced to nitrogen (N2), a process known as iron autotrophic denitrification. This process requires no organic carbon source, perfectly solving the problem of insufficient carbon source for denitrification in low C / N wastewater. 2+ It returns to the aerobic zone through the separation unit, starting a new oxidation cycle. This Fe 2+ / Fe 3+ The repeated migration and transformation of electrons form a "non-contact" electron transport chain that does not rely on physical wires, efficiently coupling the nitrification reaction in the aerobic zone with the denitrification reaction in the anaerobic zone, greatly enhancing the system's total nitrogen removal capacity. The separator is a porous ceramic plate with a pore size of 0.1-10 μm.

[0021] (ii) Confined electro-Fenton synergistic degradation at micro-iron-oxygen interfaces

[0022] The tight spacing of 0.5-5 mm (preferably 1-3 mm) between the oxygen-supplying membrane fibers and the iron-based unit is key to achieving efficient chemical oxidation. At this micro-distance, the path for oxygen to diffuse from the membrane surface to the iron-based material surface is extremely short, forming a local oxygen-rich region with high concentration and steep gradient. The hollow fiber membrane fibers are made of poly-4-methyl-1-pentene; the surface of the hollow fiber membrane fibers is coated with a conductive coating, which is a composite conductive coating containing carbon materials and stable ferrous iron; wherein, the carbon material is selected from one or more of carbon nanotubes, graphene, or graphene oxide; the stable ferrous iron is selected from one or more of magnetite (Fe3O4) nanoparticles, ferrous iron-doped conductive polymers, etc., the coating thickness is 5-50 μm, and the resistivity is <100 Ω·cm.

[0023] Meanwhile, if a composite conductive coating of carbon material and stable ferrous iron is applied to the surface of the hollow fiber membrane, this conductive coating will undergo a two-electron oxygen reduction reaction (2e) in the presence of oxygen. - ORR generates hydrogen peroxide (H2O2). On the other hand, as part of the iron source, Fe is directly released from the membrane fiber surface. 2+ H2O2 reacts with Fe continuously released from the surface of the iron-based unit. 2+ And Fe released by the coating 2+ The classical Fenton reaction (Fe2+) occurs rapidly within a very small spatial range. 2+ + H2O2 →Fe 3+ + ·OH+ OH - This generates hydroxyl radicals (·OH) with extremely high redox potentials. Even when the distance between the oxygen-supplying membrane unit and the iron-based unit is large due to device structural limitations, the conductive coating can directly provide Fe on the membrane fiber surface. 2+Even so, the effective occurrence of the electro-Fenton reaction can still be guaranteed. ·OH can non-selectively attack the stable chemical bonds (such as benzene rings, ester bonds, and carbon-halogen bonds) of recalcitrant organic compounds such as pyrethroids and halogenated aromatic hydrocarbons, achieving ring opening, chain breaking, and mineralization, significantly improving the biodegradability of wastewater and creating conditions for subsequent biodegradation. This electro-Fenton process is strictly physically confined to the iron-oxygen interface microregion, avoiding the ineffective decomposition or quenching of H2O2 and ·OH in the bulk solution, and achieving efficient utilization of reactive oxygen species.

[0024] (III) Synergistic control of in-situ chemical phosphorus removal and membrane fouling

[0025] Fe released by iron-based units in the aerobic zone 2+ Oxidized by oxygen to Fe 3+ Subsequently, under near-neutral pH conditions, they rapidly hydrolyze to form amorphous or weakly crystalline iron (hydride) oxides (such as ferrihydrite, lepidocrocite). These nanoscale particles possess a huge specific surface area (>200 m²). 2 / g) and abundant surface hydroxyl groups, which, through ligand exchange and surface complexation, affect phosphate (PO4) ions. 3- It possesses extremely strong specific adsorption capacity, thus achieving highly efficient chemical phosphorus removal. Simultaneously, the low concentrations of ·OH and H₂O₂ generated by the Fenton reaction at the iron-oxygen interface can degrade extracellular polymeric substances (EPS) attached to the surface of the membrane fibers and inside the biofilm in situ, effectively inhibiting excessive thickening and densification of the biofilm, maintaining biofilm activity, and reducing filtration resistance. Furthermore, the iron oxide biofilm / inorganic membrane composite layer formed on the surface of the iron-based unit can act as a physical barrier, preventing direct erosion of the polymer membrane material by organic solvents and emulsified oils in the wastewater, thereby extending the service life of the membrane fibers and even the entire oxygen supply membrane unit. Experiments show that the cleaning cycle of the membrane module of this invention can be extended to 1.5-2 times that of ordinary MABRs.

[0026] (iv) Enhanced electron flux regulation using multidimensional electrode systems

[0027] In a preferred embodiment, the electrode unit is a graphene / carbon cloth composite material, formed by carbon cloth with graphene loaded on its surface, and with ferrohydrate-loaded biochar filler added between the layers. The vertical distance between the electrode unit and the oxygen supply membrane unit is 10-50 cm, and the horizontal distance is 20-100 cm. Graphene has a unique Dirac band structure and high carrier mobility, which can promote rapid electron conduction and directional migration in the composite interface, significantly reducing the charge transfer impedance at the microorganism-electrode interface, promoting the rapid transfer of electrons from the microbial respiratory chain to the electrode surface, thereby enhancing the efficiency of extracellular electron transport and iron-nitrogen coupling reaction in microorganisms. Ferrohydrate-loaded biochar not only provides a huge specific surface area for microbial attachment, but also acts as an iron source to participate in the iron cycle, further enriching the electron transport pathways of the system. The resulting multi-level, three-dimensional electron transport network, spanning from the nanoscale (graphene) to the microscale (biochar, microorganisms) and then to the macroscale (electrodes, external circuits), can dynamically optimize the spatial distribution of electrons among different functional units (aerobic zone, anaerobic zone, iron-oxygen interface), enabling processes such as organic oxidation, iron reduction, and nitrate reduction to operate synergistically and according to their respective needs.

[0028] The external circuit connects the electrode unit to the conductive coating on the surface of the iron-based unit and / or the oxygen supply membrane unit, forming a closed loop. During operation, electrons generated by the electrode unit are transferred to the iron-based unit and / or the conductive coating via the external circuit to enhance pollutant removal and / or achieve energy recovery.

[0029] The system also includes a monitoring system, which includes a pH monitor, a temperature monitor, and a dissolved oxygen detector installed in the reactor. Each monitor is connected to a data collector. The data collector is used to generate control signals based on changes in dissolved oxygen concentration to adjust the oxygen supply intensity of the gas supply system.

[0030] (v) Mechanical motion enhances mass transfer and self-cleaning

[0031] In another preferred embodiment, the oxygen supply membrane unit further includes a micro-rotation drive unit. Each composite structure consisting of an oxygen supply membrane unit and an iron-based unit has a micro-rotation drive unit on the side above the water surface. The micro-rotation drive unit drives gears to rotate periodically, thereby causing the oxygen supply membrane unit and the iron-based units arranged alternately therewith to undergo periodic mechanical motion (such as slow rotation or oscillation). This motion can disrupt the stagnant boundary layer on the membrane surface, promoting interfacial mass transfer of dissolved oxygen, substrate, and iron ions; simultaneously generating moderate shear force to inhibit excessive biofilm thickening and delay membrane fouling; and enhancing fluid disturbance at the iron-oxygen interface, accelerating Fe... 2+ / Fe 3+ The mixture and the shedding of iron oxides maintain the activity of iron-based units.

[0032] Secondly, the present invention also provides a method for treating wastewater using the above-mentioned apparatus, comprising the following steps:

[0033] (a) The wastewater to be treated is introduced into the reactor so that it flows through or contacts the electrode unit, the partition unit and the alternately arranged oxygen supply membrane unit and iron-based unit in sequence;

[0034] (b) Introducing oxygen-containing gas into the oxygen supply membrane unit to perform bubble-free oxygen supply in the oxygen supply reaction zone of the membrane fibers, oxidizing ammonia nitrogen in the wastewater into nitrate nitrogen, and simultaneously reducing the Fe released by the iron-based unit and conductive coating. 2+ Oxidized to Fe 3+ Furthermore, amorphous iron oxides or iron hydroxyl oxides are generated, which are used to adsorb and fix phosphates in water; at the same time, the generated amorphous Fe(III) active iron oxides act as electron acceptors in NH4+. + The anaerobic oxidation process induces or enhances the Feammox reaction, promoting the conversion of ammonia nitrogen to N2 and NO2. - Or NO3 - Transformation into other forms; and converting inorganic nitrogen in the reflux liquid into NO3. - It exists primarily in the form of Fe in the electrode unit. 2+ Oxidation coupled with nitrate reduction provides electron acceptor conditions and a suitable redox environment, thereby achieving the synergistic removal of nitrogen and phosphorus pollutants.

[0035] (c) Contains Fe 3+ Wastewater containing nitrate nitrogen enters the low dissolved oxygen reaction zone through the separation unit. The electrode unit promotes Fe production through external circuit electron transfer and electroactive microbial mediation. 3+ Reduced to Fe 2+ This achieves in-situ regeneration of ferrous ions; simultaneously, the generated Fe... 2+ As an electron donor, it participates in the reduction of nitrate nitrogen, resulting in Fe 2+ Oxidation coupled with nitrate reduction reaction gradually reduces nitrate nitrogen into nitrogen gas, thereby achieving denitrification of wastewater.

[0036] (d)Fe 2+ The iron is returned to the oxygen supply reaction zone of the membrane filament through the separation unit, forming an iron cycle.

[0037] Furthermore, the oxygen supply membrane unit has a conductive coating on its surface. In step (b), the conductive coating catalyzes the oxygen reduction reaction to generate hydrogen peroxide, which then reacts with Fe... 2+ The Fenton reaction generates hydroxyl radicals to degrade organic pollutants (such as pyrethroid pesticide wastewater); the method also includes a step of recirculating a portion of the effluent back to the reactor inlet, with a recirculation ratio of 20-100%.

[0038] Beneficial effects:

[0039] Compared with existing technologies, the wastewater treatment device based on iron redox conversion membrane fiber oxygen supply and electrode synergy provided by the present invention has the following beneficial effects:

[0040] (1) Excellent denitrification performance: by constructing Fe 2+ / Fe 3+ The circulation-mediated non-contact electron transfer tightly integrates aerobic nitrification with anaerobic iron-autotrophic denitrification, effectively solving the problem of insufficient denitrification efficiency in traditional MABR systems. It can significantly improve the total nitrogen removal rate for wastewater with low C / N ratios.

[0041] (2) Highly efficient in-situ chemical phosphorus removal: Phosphorus is removed by adsorption and precipitation of iron (hydrogen) oxides generated in situ during the iron oxidation process, without the need for external chemical reagents, thus achieving "waste treatment with waste". The total phosphorus removal rate can be stably maintained at over 85%.

[0042] (3) Enhanced removal capacity of recalcitrant organic matter: Through in-situ electro-Fenton reaction confined at the micro-iron-oxygen interface, hydroxyl radicals are continuously generated, which can efficiently mineralize stubborn organic pollutants such as pyrethroids, antibiotics, and halogenated compounds that are difficult to treat by traditional biological methods, improve the biodegradability of wastewater, and ensure the ecological safety of effluent.

[0043] (4) Low energy consumption and potential energy recovery: The oxygen utilization rate of the membrane fiber bubble-free oxygen supply is close to 100%, and the aeration energy consumption is much lower than that of traditional mechanical aeration. At the same time, when the system is running as a microbial fuel cell, it can generate electricity to provide energy for monitoring equipment, valve actuators, etc., which is conducive to achieving energy self-sufficiency or carbon neutrality in the treatment process.

[0044] (5) Excellent operational stability and anti-fouling ability: The low dose of active oxygen generated at the iron-oxygen interface can effectively inhibit the excessive growth of biofilm and delay membrane fouling; the inorganic protective layer on the surface of the iron-based unit can resist the chemical erosion of organic solvents, significantly extend the service life and cleaning cycle of the membrane module, and reduce operation and maintenance costs.

[0045] (6) Compact structure and flexible expansion: The device integrates multiple functions such as anaerobic / aerobic zoning, BES electrode, MABR membrane, iron circulation chemical phosphorus removal and advanced oxidation into one unit, with a highly compact structure that saves space. The oxygen supply membrane unit and the iron-based unit can adopt a standard modular design, which is convenient for flexible combination and engineering scale-up according to different water treatment volumes and pollutant loads. Attached Figure Description

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0047] Figure 1 This is a schematic diagram of the overall structure of the wastewater treatment device in Embodiment 1 of the present invention.

[0048] Figure 2 This is a partial structural diagram of the electrode unit in Embodiment 1 of the present invention.

[0049] Figure 3 This is a schematic diagram of the graphene / carbon cloth composite material in Example 1 of the present invention.

[0050] Figure 4 This is a schematic diagram of the structure of the partition unit (porous ceramic partition) in Embodiment 1 of the present invention.

[0051] Figure 5 This is a schematic diagram of the oxygen supply membrane unit in Embodiment 1 of the present invention.

[0052] Figure 6 This is a schematic diagram of one side of the oxygen supply membrane unit in Embodiment 1 of the present invention.

[0053] Figure 7 This is a schematic diagram of the composition structure of the iron-based unit in Embodiment 1 of the present invention.

[0054] Figure 8 This is a partially enlarged schematic diagram of the alternating arrangement of oxygen supply membrane units and iron-based units in Embodiment 1 of the present invention.

[0055] Figure 9 This is a schematic diagram of the connection relationship of the gas supply system in Embodiment 1 of the present invention.

[0056] Figure 10 This is a schematic diagram of the anaerobic zone (low dissolved oxygen reaction zone) in Embodiment 1 of the present invention.

[0057] Figure 11 This is a schematic diagram of the aerobic zone (membrane fiber oxygen supply reaction zone) in Embodiment 1 of the present invention.

[0058] Figure 12 Iron ions (Fe) during operation of the device in Embodiment 1 of the present invention 2+ / Fe 3+ A schematic diagram of the migration path within the reactor.

[0059] In the diagram, the various reference numerals represent:

[0060] 1-Reactor; 2-Electrode unit; 3-Oxygen supply membrane unit; 4-Iron-based unit; 5-Separation unit; 6-Fixing unit; 7-External circuit; 8-Gas supply system; 9-Monitoring system;

[0061] 101-Inlet; 102-Water pump; 103-pH monitor; 104-Temperature monitor; 105-Dissolved oxygen detector; 106-Outlet; 107-Sludge discharge port; 108-Titanium wire; 109-Variable resistance box; 110-Data collector; 111-Data workbench; 112-Flow monitor;

[0062] 201-Graphene; 202-Carbon cloth; 203-Electrogenic microorganisms; 204-Hydroferrite-supported crayfish biochar filler; 205-Graphene / carbon cloth composite material; 206-Conductive layer;

[0063] 301 - Hollow fiber membrane filament; 302 - Micro rotary drive unit; 303 - Gear; 304 - Conductive coating

[0064] 401 - Iron-based alloy wire; 402 - Iron shavings; 403 - Porous ceramic particles loaded with nano-sized ferrous oxide

[0065] 501 - Porous ceramic separator;

[0066] 801-Air pump; 802-Buffer tank; 803-Precision filter; 804-Pressure gauge; 805-Switch valve; 806-Pressure reducing valve; 807-Gas flow meter. Detailed Implementation

[0067] The present invention can be better understood from the following embodiments.

[0068] Example 1: Construction of a wastewater treatment device

[0069] This embodiment provides a specific wastewater treatment device based on iron redox conversion, which combines membrane fiber oxygen supply with electrode synergy.

[0070] Reference Figure 1 A wastewater treatment device includes a cubic reactor 1, an electrode unit 2, an oxygen supply membrane unit 3, multiple iron-based units 4, a partition unit 5, a fixing unit 6, an external circuit 7, an air supply system 8, and a monitoring system 9.

[0071] Reactor 1: Constructed of transparent acrylic glass for easy observation of its internal operation. It has an effective volume of 10L and internal dimensions of 30 cm (length) × 30 cm (width) × 30 cm (height). The left side of the reactor is the low dissolved oxygen reaction zone (or anaerobic zone), and the right side is the membrane fiber oxygen supply reaction zone (or aerobic zone). An inlet 101 is located on the bottom sidewall of the reactor, with water intake controlled by a peristaltic pump 102. An outlet 106 is located on the upper sidewall of the reactor, allowing water to overflow by gravity. A sludge discharge port 107 is located at the bottom center for periodic discharge of excess sludge or iron sludge. The reactor also houses a pH monitor 103, a temperature monitor 104, and a dissolved oxygen detector 105, all connected to a data collector 110.

[0072] Electrode unit 2: such as Figure 1 , Figure 2 As shown, the electrode unit is located in the lower middle part of the anaerobic zone on the left side of the reactor. It consists of four layers of graphene / carbon cloth composite material 205 stacked together, with each layer of carbon cloth interspersed with crayfish biochar filler 204 loaded with ferrophosphate. The filler layer thickness is approximately 1 cm. The preparation method of graphene / carbon cloth composite material 205 is as follows: First, commercially available carbon cloth 202 (20 cm × 5 cm area) is ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 30 minutes to remove surface contaminants. Then, graphene oxide powder is ultrasonically dispersed in deionized water to prepare a dispersion of 1 mg / mL. The cleaned carbon cloth is immersed in this dispersion and allowed to stand for 12 hours. After removal, it is dried in a 60℃ oven. Finally, the dried carbon cloth is immersed in a 0.1 M sodium borohydride solution and reacted at 95℃ for 30 minutes to reduce graphene oxide to reduced graphene oxide 201, obtaining graphene / carbon cloth composite material 205. Before use, the composite material was soaked in a bacterial solution enriched with Geobacter sulfurreducens (concentration approximately 10). 8 In a solution of CFU / mL, the electrodes were cultured under anaerobic conditions at 35°C for 7 days to form a stable electroactive biofilm on the electrode surface.

[0073] Oxygen supply membrane unit 3: such as Figure 1 , Figure 5 , Figure 6As shown, the oxygen supply membrane unit is located in the aerobic zone on the right side of the reactor. It consists of 50 poly(4-methyl-1-pentene) (PMP) hollow fiber membrane filaments 301. Each filament has an outer diameter of 500 μm, a wall thickness of 50 μm, and an effective length of 50 cm. One end of all filaments is encapsulated and sealed with epoxy resin, and the other end is bundled and connected to the gas supply system 8. A conductive coating 304 is coated onto the surface of the membrane filaments using an dip-coating method. Specifically, carbon nanotubes and iron oxide nanoparticles are dispersed in N-methylpyrrolidone, polyvinylidene fluoride is added as a binder, the membrane filaments are immersed in the dispersion and then lifted at a constant speed, repeated twice, and dried at 60°C for 12 hours to form a conductive coating with a thickness of approximately 10 μm and a resistivity <50 Ω·cm. The membrane fiber bundle and the iron-based unit are fixed together with epoxy resin to form multiple composite structures. Each structure is fitted with a fixing gear 303. The bottom of each fixing gear 303 is connected to a miniature rotary drive unit 302 (DC geared motor, speed 0.5 rpm), which can drive the membrane fiber bundle and the iron-based unit 4 interspersed therein to oscillate back and forth at a frequency of about 0.5 Hz.

[0074] Iron-based unit 4: such as Figure 7 , Figure 8 As shown, it consists of iron shavings 402, iron-based alloy wire 401 (iron wire, carbon content 0.1%), and porous ceramic particles 403 loaded with nano-sized ferrous oxide. The iron-based alloy wire 401 is twisted together to form a filamentous skeleton supporting the outer structure. The internal voids are filled with iron powder, iron shavings 402, and porous ceramic particles 403 loaded with nano-sized ferrous oxide, forming a composite integrated structure of outer filaments, inner powder, and skeleton-filled structure. The diameter is approximately 5 mm, and the length is the same as the effective length of the membrane filament. Before use, the iron-based unit is immersed in 0.1 M hydrochloric acid for 5 minutes to remove the surface oxide layer, and then rinsed with deionized water until neutral. The hollow fiber membrane filaments 301 of the iron-based unit 4 and the oxygen supply membrane unit 3 are arranged alternately in the spatial direction, and the surface distance between them is precisely controlled to 2 mm by the fixing unit 6 (see [link to documentation]). Figure 8 ).

[0075] Separator 5: such as Figure 1 , Figure 4 As shown, a porous ceramic separator (501) is vertically positioned between the anaerobic and aerobic zones. The separator measures 20 cm × 25 cm, is 5 mm thick, and has an average pore size of 0.1–10 μm. This separator allows Fe… 2+ / Fe 3+ NO3 - Dissolved ions and molecules such as -N can pass through, but it can effectively block the diffusion of dissolved oxygen from the aerobic zone to the anaerobic zone, maintaining the dissolved oxygen concentration in the anaerobic zone at <0.2 mg / L during actual operation.

[0076] Fixing Unit 6: A corrosion-resistant polypropylene frame is used to securely fix the electrode unit 2, oxygen supply membrane unit 3, iron-based unit 4, and partition unit 5 to the designated positions within the reactor 1.

[0077] External circuit 7: such as Figure 1 As shown, titanium wire 108 is used to connect the titanium current collector of electrode unit 2 to the lead-out terminal of iron-based unit 4 and the lead-out wire of conductive coating 304 of oxygen supply membrane unit 3. A variable resistor box 109 (adjustable range 0-1000 Ω) is connected in series in the circuit, and a data acquisition unit 110 and a data workbench 111 are connected to it for real-time monitoring and recording of the system's output voltage and current.

[0078] Gas supply system 8: such as Figure 9 As shown, an air pump 801, a buffer tank 802, a precision filter 803 (filtration accuracy 0.22μm), a pressure gauge 804, a switching valve 805, a pressure reducing valve 806, and a gas flow meter 807 are sequentially connected to the air inlet of the oxygen supply membrane unit 3 via pressure-resistant pipelines. During operation, the oxygen supply pressure inside the membrane is controlled at 0.02-0.04 MPa, and the gas flow rate is adjusted based on dissolved oxygen feedback.

[0079] Example 2: A method for wastewater treatment using the aforementioned device

[0080] This embodiment provides a method for treating actual wastewater using the apparatus described in Example 1. The wastewater to be treated is a comprehensive wastewater source from a pesticide factory's production workshop. The main pollutants include cypermethrin (approximately 15-25 mg / L), fenvalerate (approximately 5-10 mg / L), COD approximately 800-1000 mg / L, ammonia nitrogen approximately 45-55 mg / L, total phosphorus approximately 8-12 mg / L, and a BOD5 / COD ratio of approximately 0.18. It has poor biodegradability and contains a small amount of xylene solvent.

[0081] The specific steps of the operation are as follows:

[0082] S1: System Startup and Microbial Inoculation

[0083] After the apparatus constructed in Example 1 was installed, wastewater to be treated was continuously injected into reactor 1, ensuring the liquid level completely submerged the oxygen supply membrane unit 3. Electrode unit 2 had been pre-inoculated with Geobacter sulfurreducens as described in Example 1. For the surface of the oxygen supply membrane unit 3, a natural biofilm formation method was used: under continuous water inflow and an oxygen supply pressure of 0.01 MPa, after approximately 7-10 days, a uniform light yellow biofilm was visible to the naked eye on the surface of the membrane filaments. Microscopic examination showed a dense biofilm structure, indicating successful biofilm formation. At this point, the system entered a stable operating phase.

[0084] S2: Aerobic zone operation (nitrification, iron oxidation, phosphorus removal and electro-Fenton degradation)

[0085] Turn on the gas supply system 8, and adjust the pressure reducing valve 806 and gas flow meter 807 to stabilize the oxygen pressure inside the oxygen supply membrane unit 3 at 0.03 MPa. The hydraulic retention time (HRT) of the wastewater in the aerobic zone is controlled at 6 hours. The dissolved oxygen concentration in the main solution of the aerobic zone is maintained at 0.5-14 mg / L, as monitored by the dissolved oxygen detector 105.

[0086] The following processes occur simultaneously in the aerobic zone:

[0087] Nitrification: Aerobic ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) attached to the surface of the oxygen supply membrane filament 301 nitrate nitrogen (NH4+) in wastewater. + -N) is successively oxidized to nitrite (NO2) - -N) and nitrates (NO3) - -N).

[0088] Iron oxidation and in-situ chemical phosphorus removal: Iron-based unit 4 continuously releases Fe in a weakly acidic / near-neutral microenvironment. 2+ Because the distance between the Fe and the oxygen-supplying membrane filaments is less than 5 mm, Fe 2+ It is rapidly oxidized to Fe by dissolved oxygen. 3+ Subsequently, it hydrolyzes to generate amorphous iron hydroxyl oxides (FeOOH) and other iron (hydride) oxides. These nascent iron minerals have a very high specific surface area, and through surface complexation and co-precipitation, they efficiently adsorb phosphates in wastewater, forming Fe-P precipitates, which are discharged from sludge outlet 107 along with the remaining sludge.

[0089] Confined electro-Fenton reaction and degradation of recalcitrant organic matter: The conductive coating 304 on the surface of the oxygen-supplying membrane fiber acts as a cathode, where a two-electron oxygen reduction reaction occurs in the presence of dissolved oxygen: O2 + 2H+ + + 2e - → H2O2. The generated H2O2 reacts with Fe. 2+ The Fenton reaction occurs rapidly within a micrometer-scale space: Fe 2+ + H2O2 →Fe 3+ + ·OH + OH - The generated hydroxyl radicals (·OH) possess strong electrophilic properties, immediately attacking organic molecules such as cypermethrin and deltamethrin in the wastewater, disrupting their ester bonds, halogen substituents, and aromatic ring structures, achieving ring-opening and chain scission. This decomposes large, recalcitrant organic molecules into smaller organic acids or carbon dioxide and water, significantly reducing the biotoxicity of the wastewater and improving its biodegradability. Simultaneously, the anoxic state of this unit facilitates the hydrolysis of pyrethroid molecules, further promoting their degradation.

[0090] S3: Inter-regional migration and anaerobic zone operation (iron reduction and iron autotrophic denitrification nitrogen removal)

[0091] The mixed solution in the aerobic zone (rich in NO3) - -N、 Fe 3+ Residual organic matter and ·OH reaction products diffuse through the porous ceramic baffle (501) or enter the anaerobic zone with the water flow. The HRT in the anaerobic zone is controlled at 6 hours. Due to the oxygen barrier effect of the porous ceramic plate, the dissolved oxygen concentration in the anaerobic zone is stably maintained at <0.1 mg / L.

[0092] The following processes occur simultaneously in the anaerobic zone:

[0093] Iron reduction: Electroactive microorganisms such as *Geobacter sulfurreducens* attached to electrode unit 2 utilize the incompletely degraded organic matter in the aerobic zone (or direct electrons from the electrode) as electron donors to reduce the diffused Fe... 3+ Reduced to Fe 2+ 2 Fe 3+ + Organic matter → 2 Fe 2+ + CO2 + H + .

[0094] Iron autotrophic denitrification: The Fe produced in the above process 2+ And a small amount of Fe diffused directly from the aerobic zone 2+ As an inorganic electron donor, it can remove nitrates (NO3) from wastewater. - -N) is reduced to nitrogen gas (N2), thus achieving denitrification. The main reaction formula is: 10 Fe 2+ + 2 NO3 - + 12H + → 10 Fe 3+ + N2 + 6H2O. This process requires no organic carbon source, compensating for the low C / N ratio of the raw water. Simultaneously, Fe... 2+ It can also be used as an electron donor to convert nitrite (NO2) - -N) is reduced to N2.

[0095] Anaerobic digestion of residual organic matter: Some simple organic matter is further degraded into methane and other substances under the action of anaerobic bacteria, but the main organic removal pathway in this system is aerobic and advanced oxidation.

[0096] After anaerobic treatment, the effluent NO3 - -N concentration decreased significantly.

[0097] S4: Electron Transfer and Electricity Generation

[0098] Electrons generated by the metabolism of electrogenic microorganisms on electrode unit 2 are partially used to directly reduce Fe.3+ Another portion is transferred through the graphene / carbon cloth electrode 205 and the external circuit 7 to the composite cathode, which consists of the iron-based unit 4 and the conductive coating 304 on the oxygen supply membrane surface. The variable resistance box 109 Ω is adjusted to 100 Ω to form a closed loop. The generated electrical energy can be stored in a supercapacitor or directly used to drive low-power devices such as micro-pumps and monitoring sensors.

[0099] S5: Iron ion circulation and effluent recirculation

[0100] Fe is reduced in the anaerobic zone to form Fe 2+ And some Fe that did not participate in denitrification 2+ Through concentration gradient diffusion and the pores of separating unit 5, these Fe atoms return to the aerobic zone. 2+ Re-oxidized to Fe 3+ This initiates a new iron oxidation-reduction cycle. To enhance system treatment efficiency and buffer influent shock, an effluent recirculation system is implemented: a portion of the effluent from the end of the aerobic zone is pumped back to reactor inlet 101 at a recirculation ratio of 50% using a recirculation pump, mixed with the influent, and then reintroduced into the system. The Fe in the recirculated solution... 2+ Nitrates and microorganisms can optimize the material distribution and microbial community structure within the reactor.

[0101] S6: Water Discharge and System Maintenance

[0102] The wastewater treated by the above units overflows from the outlet 106 at the top of the reactor. During continuous operation, parameters such as pH, temperature, and DO are monitored in real time by the monitoring system 9. Based on changes in DO value, the data collector 110 automatically adjusts the oxygen supply pressure or intermittent oxygen supply cycle of the aeration system 8 using a PID algorithm (e.g., suspending oxygen supply for 30 minutes when DO > 4 mg / L), achieving dynamic and precise control of oxygen diffusion flux and avoiding Fe... 2+ Rapid oxidation and deposition on the membrane fiber surface forms a dense scale layer, thereby maintaining the oxygen permeability of the membrane fiber and the activity of the iron-based unit. A small amount of iron-phosphorus sludge is discharged weekly through sludge discharge port 107 to maintain the iron-sludge balance within the system.

[0103] Example 3: Operational Results and Comparative Experiment

[0104] Using the method described in Example 2, the device constructed in Example 1 was operated continuously and stably for 90 days. During this period, the influent and effluent water quality were periodically monitored, and the results are as follows:

[0105] COD: The average influent COD was 915 mg / L, and the average effluent COD was 100.65 mg / L, with an average removal rate of 89%.

[0106] Ammonia nitrogen (NH4) +-N): The average influent ammonia nitrogen was 53 mg / L, the average effluent ammonia nitrogen was 10.89 mg / L, and the average removal rate was 79.5%.

[0107] Total nitrogen (TN): The average influent TN was 65 mg / L (ammonia nitrogen + organic nitrogen + nitrate nitrogen), and the average effluent TN was 15.7 mg / L, with an average removal rate of 75.8%. This nitrogen removal effect is significantly better than that of traditional MABR (which typically has a TN removal rate of <50%), demonstrating the effectiveness of iron autotrophic denitrification.

[0108] Total phosphorus (TP): The average TP in the influent was 8.5 mg / L, and the average TP in the effluent was 2.3 mg / L, with an average removal rate of 73%.

[0109] Iron recycling efficiency: By analyzing the total iron content in the influent, effluent and sludge, it was estimated that about 85% of the iron ions released by the iron-based unit participate in the recycling (i.e., are reduced and then re-oxidized), indicating that the iron recycling has good sustainability.

[0110] Comparative experimental setup and results:

[0111] To verify the beneficial effects of the key structural features of the present invention, the following control group was set up and operated under the same influent water quality and operating parameters. The operating results are shown in Table 1.

[0112] Table 1

[0113]

[0114] The results of the comparative experiment show that:

[0115] (1) The introduction of iron-based units is the key to simultaneously achieving efficient phosphorus removal and enhanced denitrification (iron autotrophic denitrification).

[0116] (2) Micro-spacing (0.5-5 mm) alternating iron-oxygen arrangement is crucial for generating efficient confined electro-Fenton reactions and degrading recalcitrant organic matter. When the spacing is increased to 10 mm, the effective concentration of ·OH decreases significantly, and the pyrethroid removal rate decreases significantly.

[0117] (3) The presence of the partition unit maintains a strict anaerobic / aerobic partition, ensuring the activity of iron-autotrophic denitrifying bacteria and electrogenic bacteria, and making a significant contribution to total nitrogen removal.

[0118] (4) The conductive coating on the surface of the oxygen supply membrane not only contributes the source of H2O2 required for electro-Fenton, but also enhances the electrochemical reduction pretreatment and oxidative degradation of pyrethroid organic compounds.

[0119] In summary, the embodiments demonstrate that the device and method of the present invention have a strong synergistic effect and high operational reliability in treating wastewater containing recalcitrant organic matter and low C / N ratio.

[0120] This invention provides a wastewater treatment device and method based on iron redox conversion, utilizing membrane fiber oxygen supply and electrode synergy. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A wastewater treatment device based on iron redox conversion, combining membrane fiber oxygen supply with electrode synergy, characterized in that, include: The reactor (1) is provided with an inlet (101) and an outlet (106), and its interior is divided into at least a low dissolved oxygen reaction zone and a membrane fiber oxygen supply reaction zone; an electrode unit (2) is disposed in the low dissolved oxygen reaction zone and is used to enrich electroactive microorganisms and degrade organic matter; an oxygen supply membrane unit (3) is disposed in the membrane fiber oxygen supply reaction zone and includes at least one hollow fiber membrane fiber (301) for bubble-free oxygen supply to the membrane fiber oxygen supply reaction zone; an iron-based unit (4) is disposed in the membrane fiber oxygen supply reaction zone and is positioned at a distance of 0.5-5 from the oxygen supply membrane unit (3) in the spatial direction. The iron-oxygen alternating interface reaction zone is formed by alternating spacing of mm; the separator unit (5) is set between the electrode unit (2) and the oxygen supply membrane unit (3) to maintain the redox partition between the low dissolved oxygen reaction zone and the membrane fiber oxygen supply reaction zone, and to allow iron ions to migrate between the two zones; the gas supply system (8) is connected to the oxygen supply membrane unit (3) to provide oxygen-containing gas; when the device is running, the membrane fiber oxygen supply reaction zone forms a local oxidation micro-region around the membrane fiber, promoting the conversion of ammonia nitrogen to nitrate nitrogen, while the iron-based unit (4) releases Fe 2+ It is oxidized to Fe in this region 3+ Iron oxides are generated to remove phosphate; some iron ions migrate through the separator (5) to the low dissolved oxygen reaction zone and are then reduced to Fe. 2+ This achieves the cyclic conversion of iron ions; nitrate nitrogen from the oxygen supply reaction zone of the membrane fiber is converted into Fe in the low dissolved oxygen reaction zone. 2+ It uses electron donors to undergo reduction reactions, thereby achieving denitrification.

2. The wastewater treatment device according to claim 1, characterized in that, The distance between the oxygen supply membrane unit (3) and the iron-based unit (4) is 0.5-5mm; each composite structure consisting of the oxygen supply membrane unit (3) and the iron-based unit (4) is provided with a micro-rotation drive unit (302) on the side above the water surface. The micro-rotation drive unit (302) drives the gear (303) to rotate periodically, causing the composite of the oxygen supply membrane unit (3) and the iron-based unit (4) to produce regular mechanical movement. By utilizing the interface shearing and mechanical disturbance generated by the movement, the shedding and attachment of biofilm on the surface of the membrane filaments are controlled, thereby stabilizing and maintaining a suitable biofilm thickness.

3. The wastewater treatment device according to claim 1, characterized in that, The electrode unit (2) includes a graphene / carbon cloth composite material (205), which is formed by carbon cloth (202) with graphene (201) loaded on its surface, and a biochar filler (204) loaded with ferrophosphate is disposed between adjacent carbon cloth layers.

4. The wastewater treatment device according to claim 1, characterized in that, The separating unit (5) is a porous ceramic separator (501) with a pore size of 0.1-10 μm; the vertical distance between the electrode unit (2) and the oxygen supply membrane unit (3) is 10-50 cm and the horizontal distance is 20-100 cm.

5. The wastewater treatment device according to claim 1, characterized in that, The hollow fiber membrane filament (301) is made of poly4-methyl-1-pentene; the surface of the hollow fiber membrane filament (301) is coated with a conductive coating (304), which is a composite conductive coating containing carbon material and stable ferrous material; wherein, the carbon material is selected from one or more of carbon nanotubes, graphene or graphene oxide; the stable ferrous material is selected from one or more of iron(III) oxide nanoparticles, ferrous doped conductive polymers, etc.; the coating thickness is 5-50 μm and the resistivity is <100 Ω·cm.

6. The wastewater treatment device according to claim 1, characterized in that, The iron-based unit (4) is a filamentous composite structure formed by twisting iron-based alloy wires (401) to form a filamentous skeleton outer support structure, and filling the internal gaps with iron shavings (402) and porous ceramic particles (403) loaded with nano-sized ferrous oxide; the iron-based unit (4) is not directly electrically connected to the oxygen supply membrane unit (3), but is connected through Fe 2+ / Fe 3+ The redox cycle forms a non-contact electron transfer path between the electrode unit (2) and the oxygen supply membrane unit (3); and the hollow fiber membrane filament (301) of the oxygen supply membrane unit (3) is coated with a conductive coating (304).

7. The wastewater treatment apparatus according to claim 1 or 5, characterized in that, The device also includes an external circuit (7), which connects the electrode unit (2) to the conductive coating (304) on the surface of the iron-based unit (4) and / or the oxygen supply membrane unit (3) to form a closed loop. During operation, the electrons generated by the electrode unit (2) are transferred to the iron-based unit (4) and / or the conductive coating (304) via the external circuit (7) to enhance pollutant removal and / or realize energy recovery.

8. The wastewater treatment device according to claim 1, characterized in that, It also includes a monitoring system (9), which includes a pH monitor (103), a temperature monitor (104) and a dissolved oxygen detector (105) installed in the reactor. Each monitor is connected to a data collector (110). The data collector (110) is used to generate control signals based on changes in dissolved oxygen concentration to adjust the oxygen supply intensity of the gas supply system (8).

9. A method for wastewater treatment using the apparatus according to any one of claims 1-8, characterized in that, Includes the following steps: (a) The wastewater to be treated is introduced into the reactor (1), and flows sequentially through or into contact with the electrode unit (2), the separator unit (5), and the alternately arranged oxygen supply membrane unit (3) and iron-based unit (4); (b) Oxygen-containing gas is introduced into the oxygen supply membrane unit (3), and bubble-free oxygen supply is carried out in the membrane fiber oxygen supply reaction zone to oxidize the ammonia nitrogen in the wastewater into nitrate nitrogen, while the Fe released by the iron-based unit (4) is oxidized. 2+ Oxidized to Fe 3+ (c) Contains Fe 3+ Wastewater containing nitrate nitrogen enters the low dissolved oxygen reaction zone through the separation unit (5), where electroactive microorganisms on the electrode unit (2) utilize organic matter to convert Fe into nitrogen. 3+ Reduced to Fe 2+ At the same time, Fe 2+ (d)Fe acts as an electron donor to reduce nitrate nitrogen to nitrogen gas, thus achieving denitrification; 2+ The iron cycle is formed by returning to the oxygen supply reaction zone of the membrane filament through the separation unit (5).

10. The method according to claim 9, characterized in that, The oxygen supply membrane unit (3) has a conductive coating (304) on its surface. In step (b), the conductive coating (304) catalyzes the oxygen reduction reaction to generate hydrogen peroxide, which reacts with Fe... 2+ The Fenton reaction generates hydroxyl radicals to degrade organic pollutants; the method also includes a step of recirculating a portion of the effluent back to the reactor inlet, with a recirculation ratio of 20-100%.

Images