An electro-Fenton sewage treatment system and its application

Abstract

The present invention discloses an electro-Fenton sewage treatment system and a method for treating wastewater, wherein the electro-Fenton sewage treatment system comprises an iron sludge reduction unit, an electro-Fenton oxidation zone, a coagulation sedimentation zone, and an energy storage power supply system connected to the electro-Fenton oxidation zone, and further comprises a microbial fuel cell type artificial wetland unit respectively connected to the coagulation sedimentation zone and the energy storage power supply system; the microbial fuel cell type artificial wetland unit is connected to the coagulation sedimentation zone through an overflow pipe; the microbial fuel cell type artificial wetland unit is provided with a water distribution layer, a first filler layer, a bioanode, a second filler layer and an electrochemical cathode from bottom to top; microorganisms with electricity generation and iron reduction functions are attached to the bioanode. When the method of the present invention is used to treat sewage, the removal efficiency of acid red B dye reaches more than 87%, and the removal efficiency of COD reaches more than 82%.

Description

Technical Field

[0001] The present invention relates to an electro-Fenton sewage treatment system and application thereof, in particular to an electro-Fenton sewage treatment system powered by an artificial wetland fuel cell and application thereof, belonging to the field of water pollution control and water treatment. Background Art

[0002] With the development of printing and dyeing industry, the discharge of acid dye wastewater is increasing day by day, and it has become one of the most important sources of water pollution. Acid dye wastewater has the characteristics of large chromaticity, complex composition, poor biodegradability, stable chemical properties of pollutants, and strong antioxidant capacity, which poses a threat to public health and safety. The research on its treatment process has also become an urgent problem to be solved.

[0003] At present, advanced oxidation technologies include photocatalysis, chemical Fenton, photo-Fenton, and electro-Fenton processes. Chemical Fenton oxidation can be achieved by adding Fe 2+ Under acidic conditions, H2O2 is catalyzed to generate highly oxidizing hydroxyl radicals (·OH), which can be used to completely degrade organic matter and improve the biodegradability of refractory organic matter. The electro-Fenton method can generate H2O2 and Fe in situ by applying external electrical energy. 2+ , thereby reducing the production and transportation costs of reagents, and has attracted widespread attention. The prior art (application number: 2015109097187) discloses a Fenton oxidation-biological combined treatment process for sludge reduction using ozone-anaerobic iron reduction. In this process, (1) the biochemical effluent of printing and dyeing wastewater enters Fenton oxidation-hydrolysis acidification-aerobic treatment; (2) the iron-containing sludge produced by the Fenton oxidation unit and the biological treatment sludge are added to the ozone reaction tank in proportion to react; (3) the sludge enters the anaerobic iron reduction reactor to react, and 90% of the Fe in the sludge is reduced. 3+ Reduction to form Fe 2+ ; (4) Fe in the anaerobic iron reduction reactor 2+ The solid-liquid reaction products are returned to the front end of the Fenton oxidation-biological combined treatment process to partially replace the exogenously added Fe 2+ , and reduce the amount of sludge during operation.

[0004] Although the above-mentioned electro-Fenton system reduces the input of iron sludge, there is still iron sludge remaining, and the problem of waste pollution to the environment has not been completely solved; moreover, the above-mentioned electro-Fenton system uses chemical methods to reduce iron, which consumes a lot of energy and has high operating costs, which greatly limits the practical application of electro-Fenton; in addition, in this anaerobic iron reduction reaction, Fe 3+ Cannot be completely reduced, Fe 3+ Not fully utilized.

[0005] The bottom layer of the constructed wetland microbial fuel cell (CW-MFC) is an anaerobic environment, which is suitable for the survival of microorganisms. A large number of power-producing microorganisms such as Geobacter have dissimilatory iron reduction, which can reduce Fe(III) in iron oxides to form Fe(II), thereby oxidizing and removing organic matter while generating electricity and increasing the degradation rate of organic pollutants. However, the input of external energy is difficult. Therefore, it is extremely important to solve the problem of external energy input.

[0006] At present, there is no report on the organic combination of electro-Fenton oxidation and artificial wetland microbial fuel cells, and the in-situ utilization of iron in iron sludge to supply the electro-Fenton system. Summary of the invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for reducing the discharge of iron-containing sludge and saving Fe in the Fenton oxidation unit. 2+ An electro-Fenton wastewater treatment system and its application which can reduce the dosage, the cost of iron sludge treatment and the operating cost and effectively improve the degradation efficiency of acid dye wastewater.

[0008] Technical solution: In order to solve the above technical problems, the present invention provides an electro-Fenton sewage treatment system for the first time, comprising an iron sludge reduction unit for reducing iron sludge, an electro-Fenton oxidation zone, a coagulation and sedimentation zone, and an energy storage and power supply system connected to the electro-Fenton oxidation zone, which are connected to each other, and also comprising a microbial fuel cell type artificial wetland unit connected to the coagulation and sedimentation zone and the energy storage and power supply system respectively; the microbial fuel cell type artificial wetland unit is connected to the coagulation and sedimentation zone through an overflow pipe; the microbial fuel cell type artificial wetland unit is provided with a water distribution layer, a first filler layer, a bioanode, a second filler layer and an electrochemical cathode from bottom to top; microorganisms with electricity generation and iron reduction functions are attached to the bioanode, and the electric energy generated by the microbial fuel cell type artificial wetland unit is supplied to the electro-Fenton oxidation zone through the energy storage and power supply system.

[0009] The iron sludge reduction unit is provided with a water inlet and a water outlet, and contains a stirrer inside; the bottom of the iron sludge reduction unit is also provided with a mud inlet for iron sludge to pass through and a water inlet pipe connected to the microbial fuel cell type artificial wetland; the iron sludge reduction unit also contains microorganisms with electricity generation and iron reduction functions from the anode effluent of the microbial fuel cell type artificial wetland unit. The microorganism can be quickly enriched by using the trivalent iron in the iron sludge reduction unit under anaerobic conditions.

[0010] Among them, a low-level water collection tank is provided between the electro-Fenton oxidation zone and the iron sludge reduction unit; multiple low-level water collection tanks can be provided, so that water can be in contact with air for oxygenation during the uniform falling process, eliminating the power consumption of the blower required for aeration, thereby greatly reducing the operating costs, providing sufficient oxygen for the electro-Fenton unit, and effectively increasing the amount of H2O2 generated in the electro-Fenton unit; an anode and a cathode are provided inside the electro-Fenton oxidation zone, the anode is an iron sheet, and the cathode is a graphite plate; a water inlet regulating valve and a water outlet hole for adjusting the amount of wastewater are provided on the side wall; the sewage is further subjected to an electro-Fenton oxidation reaction.

[0011] Among them, a water inlet regulating valve connected to the water outlet is provided on the side wall of the coagulation and sedimentation zone; a sludge outlet is provided at the bottom of the coagulation and sedimentation zone, and the sludge outlet is connected to the sludge inlet of the iron sludge reduction unit through a sludge discharge pipe, and a sludge pump is provided on the sludge discharge pipe; an overflow outlet connected to the overflow pipe is also provided on the side wall of the coagulation and sedimentation zone, and the coagulation and sedimentation zone carries out coagulation and sedimentation on the trivalent iron generated in the sewage after the electro-Fenton oxidation reaction, and the generated sludge is sent to the sludge inlet at the bottom of the iron sludge reduction unit to enter the next cycle; and the generated supernatant enters the microbial fuel cell type artificial wetland unit for electricity generation reaction.

[0012] The biological anode and the electrochemical cathode are filled with magnetite, which accelerates the degradation of organic matter while generating electrical energy, and allows microorganisms with electricity generation and iron reduction functions to be rapidly enriched on the biological anode.

[0013] Among them, the energy storage power supply system includes a battery, a controller, a solar panel and a power supply circuit connected to the electro-Fenton oxidation zone; the battery, controller and power supply circuit are connected in sequence; the solar panel is connected to the controller; the controller converts the electric energy generated by the solar panel into direct current for storage in the battery; the controller also transmits the direct current stored in the battery to the electro-Fenton oxidation zone via the power supply circuit, and there is no need to add an external power source, and the system can be powered by itself.

[0014] Wherein, the microorganisms having the functions of electricity generation and iron reduction include one or more of Geobacter sulfurreducens PCA, Desulfovibrio ferrophilus IS5 and Shewanella onedensis MR-1. Preferably, the relative abundance of Geobacter sulfurreducens PCA is 20-34%, the relative abundance of Desulfovibrioferrophilus IS5 is 7-15%, and the relative abundance of Shewanella onedensis MR-1 is 1-6%.

[0015] The present invention also provides a method for treating wastewater using the electro-Fenton wastewater treatment system, comprising the following steps:

[0016] (1) Wastewater enters the iron sludge reduction unit containing microorganisms with power generation and iron reduction functions from the water inlet, so that the Fe in the iron sludge is 3+ The wastewater is then pre-treated by anaerobic degradation using the microorganisms in the iron sludge that have the functions of iron reduction and electricity production, thus obtaining Fe 2+ of wastewater;

[0017] (2) The Fe-containing 2+ The wastewater passes through the low-level water collection tank in a stepped waterfall manner and enters the electro-Fenton reaction zone (2) to undergo Fenton reaction, thereby obtaining wastewater that has undergone preliminary degradation;

[0018] (3) The wastewater that has been initially degraded in step (2) enters the coagulation and sedimentation zone through the outlet hole for coagulation and sedimentation to form iron sludge and supernatant;

[0019] (4) The iron sludge in step (3) enters the sludge discharge pipe through the sludge outlet, and is then pumped into the sludge inlet at the bottom of the iron sludge reduction unit by the sludge pump to enter the next cycle;

[0020] (5) The supernatant in step (3) passes through the overflow port and enters the overflow pipe, and then enters the bottom of the microbial fuel cell type artificial wetland unit through the water inlet. The microorganisms with iron reduction and electricity generation functions attached to the bioanode oxidize and remove organic matter in the supernatant, generate electricity, and obtain anode effluent;

[0021] (6) The anode effluent in step (5) passes through a regulating valve through a pipeline and enters the anaerobic iron sludge reduction unit through a water inlet, thereby supplementing the iron sludge reduction unit with microorganisms having iron reduction and electricity generation functions;

[0022] (7) The electrical energy in step (5) is converted into the DC power required by the electro-Fenton oxidation zone through the controller in the form of DC power via the battery, and is transmitted to the electro-Fenton oxidation zone through the power supply circuit for the next round of reaction.

[0023] Wherein, the microorganisms having the functions of electricity generation and iron reduction in step (5) include one or more of Geobactersulfurreducens PCA, Desulfovibrio ferrophilus IS5 and Shewanella onedensis MR-1.

[0024] The relative abundance of Geobacter sulfurreducens PCA is 20-34%; the relative abundance of Desulfovibrio ferrophilus IS5 is 7-15%; and the relative abundance of Shewanella onedensis MR-1 is 1-6%.

[0025] Preferably, when the relative abundances of Geobacter sulfurreducens PCA, Desulfovibrioferrophilus IS5 and Shewanella onedensis MR-1 in the iron sludge reduction unit are 26-34%, 10-15% and 3-6%, respectively, the removal efficiency of the dye and the COD removal rate of the wastewater treatment system using the electro-Fenton wastewater treatment system reaches 93%-97%, and the removal rate of the COD reaches 86%-92%.

[0026] Preferably, when the relative abundances of Geobacter sulfurreducens PCA, Desulfovibrioferrophilus IS5 and Shewanella onedensis MR-1 in the iron sludge reduction unit are 34%, 15% and 6%, respectively, the removal efficiency of the dye and the COD by the method for treating wastewater using the electro-Fenton wastewater treatment system reaches 97%, and the removal efficiency of the COD reaches 92%.

[0027] Principle of the invention: To realize the present invention, the technical difficulties that need to be overcome include how to effectively improve the ferric iron reduction rate of the iron sludge reduction unit and how to improve the hydrogen peroxide generation rate of the electro-Fenton unit. The iron sludge reduction unit collects iron sludge from the electro-Fenton unit. At the same time, the microorganisms with electricity generation and iron reduction functions enriched in the iron sludge reduction unit use the Fe in the iron sludge generated during the electro-Fenton oxidation process to generate iron sludge. 3+ Reduction to Fe 2+ , and Fe 2+ Reuse in the electro-Fenton unit to provide Fe 2+ The effluent from the electro-Fenton unit enters the coagulation sedimentation tank unit and the CW-MFC unit for deep treatment, and the electric energy generated by the CW-MFC unit is supplied to the electro-Fenton unit.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention optimizes and combines multiple technologies such as iron sludge reduction unit, electro-Fenton unit (electro-Fenton reaction zone and coagulation reaction zone), microbial fuel cell type artificial wetland unit, energy storage power supply system, etc., highlighting the overall effect; 2. The weakly acidic dye wastewater enters the iron sludge reduction zone to dissolve the iron in the iron sludge, and at the same time, microorganisms with electricity generation and iron reduction functions are enriched in the sludge, so that they can convert Fe 3+ Reduction to Fe 2+ , providing Fe for the subsequent electro-Fenton unit 2+ ; 3. After falling, the weakly acidic dye wastewater enters the electro-Fenton reaction zone, and the electro-Fenton reaction zone is supplied with dissolved oxygen by means of waterfall aeration, without the need for external oxygen; 4. The Fe generated in the iron sludge reduction zone is used by the electro-Fenton system 2+ The toxic and harmful pollutants in the weakly acidic dye wastewater are pretreated with in-situ generated hydrogen peroxide to improve the biodegradability of the wastewater (BOD / COD>0.3), thereby enhancing the power generation performance of the artificial wetland microbial fuel cell; 5. The electric energy generated by the artificial wetland fuel cell and the electric energy generated by the solar panel can be used to supply power to the electric Fenton system uninterruptedly throughout the day, which also reduces the energy consumption input of the electric Fenton system; 6. The sewage treatment system of the present invention can be used without the need for external addition of Fe 2+ The amount of H2O2 and the iron sludge produced by the electro-Fenton are returned to the iron sludge reduction unit to achieve iron reduction, which not only achieves sludge reduction, can reduce sludge discharge by 30%, and reduce the cost of subsequent sludge disposal, but also provides Fe for the subsequent electro-Fenton unit. 2+ ; 7. By organically connecting the three systems in series, the biodegradability of the dye wastewater is improved through the anaerobic pretreatment of the iron sludge reduction unit and the electro-Fenton unit, providing sufficient easily degradable organic carbon sources for the MFC-CW unit. Compared with the treatment system without the iron sludge reduction unit and the electro-Fenton unit, the toxicity of the wastewater to the electrogenic bacteria is reduced, and the power supply voltage of the MFC-CW to the electro-Fenton system is increased by 82%; 8. The present invention uses microorganisms instead of chemicals to carry out iron reduction reactions, saving production costs; 9. The removal efficiency of acid red B dye reaches more than 87%, and the removal efficiency of COD reaches more than 82%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the electro-Fenton wastewater treatment system;

[0030] Figure 2 This is the structural diagram of the energy storage power supply system;

[0031] Figure 3 Flow chart for treating wastewater using the electro-Fenton wastewater treatment system. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0033] Example 1 Composition of the electro-Fenton sewage treatment system

[0034] The iron sludge is taken from the water treatment plant. The iron-containing sludge uses iron salt as a flocculant and mainly contains soil particles, humus, organic matter, bacteria and other substances. The mass of iron in the iron-containing sludge is 37000±19740mg / kg.

[0035] The microorganisms with electricity generation and iron reduction functions in the present invention are Geobacter sulfurreducens PCA (BioWind Resource Technology Service Company, Shanghai, China), Desulfovibrio ferrophilus IS5 (Tianjin Xima Technology Co., Ltd., Tianjin, China) and Shewanella onedensis MR-1 (BioVector NTCC Plasmid Vector Bacteria Cell Gene Collection Center).

[0036] Acid dye wastewater was taken from a dye factory. The main component was 200 mg / L acid red B, the total COD concentration of the wastewater was 800 mg / L, and the pH of the wastewater was 5-6.

[0037] like Figure 1 As shown, an electro-Fenton sewage treatment system includes an iron sludge reduction unit 1 for reducing anaerobic iron sludge; an electro-Fenton unit for deep treatment of acid dye wastewater, which includes an electro-Fenton oxidation zone 2 and a coagulation and sedimentation zone 3; an energy storage power supply system 5 for supplying power to the electro-Fenton oxidation zone 2; and a microbial fuel cell type artificial wetland unit 4 for deep treatment of the effluent of the coagulation and sedimentation zone 3 and supplying power to the energy storage power supply system 5. Among them, the iron sludge reduction unit 1, the electro-Fenton oxidation zone 2, the coagulation and sedimentation zone 3 and the microbial fuel cell type artificial wetland unit 4 are connected in sequence; the microbial fuel cell type artificial wetland unit 4 is connected to the energy storage power supply system 5 and supplies power to it; and the energy storage power supply system 5 supplies power to the electro-Fenton oxidation zone 2.

[0038] The iron sludge reduction unit 1 is an anaerobic environment, and is equipped with a stirrer 1.4 to keep the anaerobic sludge in a suspended state. When used for the first time, the anaerobic sludge containing Fe(OH)3 is mixed with the anode effluent of the microbial fuel cell artificial wetland 4 (rich in microorganisms with power generation and iron reduction functions) and then added to the anaerobic tank, and anaerobic culture is carried out under anaerobic conditions to enrich the microorganisms with power generation and iron reduction functions. A water inlet 1.1 is provided at the top left side of the iron sludge reduction unit 1, and the water inlet 1.1 is connected to the wastewater reservoir for acid dye wastewater to enter; a mud inlet 1.3 is provided at the bottom of the iron sludge reduction unit 1, and the iron sludge generated in the coagulation and sedimentation area 3 enters the iron sludge reduction unit 1 through the mud inlet 1.3.

[0039] A multi-step waterfall low-level water collection tank 2.1 is provided between the electro-Fenton oxidation zone 2 and the iron sludge reduction unit 1. The effluent of the iron sludge reduction unit 1 enters the low-level water collection tank 2.1 through the outlet 1.2 in a step-by-step waterfall manner, carrying dissolved oxygen. There is an inlet regulating valve 2.2 at the bottom of the side wall of the electro-Fenton oxidation zone 2, which can flexibly adjust the pre-treated and Fe 2+ The flow rate of wastewater entering the electro-Fenton oxidation zone 2. The anode 2.4 of the electro-Fenton oxidation zone 2 is an iron sheet, and the anode electrolysis process will further produce Fe 2+ The cathode 2.5 is a graphite plate. A water outlet 2.3 is provided in the right side wall of the electro-Fenton oxidation zone 2 to connect to the coagulation and sedimentation zone 3. The water treated in the electro-Fenton oxidation zone 2 enters the coagulation and sedimentation zone 3 through the water outlet 2.3.

[0040] A water inlet regulating valve 3.1 is provided on the side wall of the coagulation and sedimentation zone 3, and a mud outlet 3.3 is provided at the bottom. The effluent carrying trivalent iron produced by the electro-Fenton oxidation zone 2 is coagulated and precipitated in the coagulation and sedimentation zone 3 to form a supernatant and iron sludge. The precipitated iron sludge enters the mud discharge pipe 3.4 through the mud outlet 3.3, and is then sent to the mud inlet 1.3 at the bottom of the iron sludge reduction unit 1 by the sludge pump 3.5; an overflow port 3.2 and an overflow pipe 3.6 are connected to the top of the coagulation and sedimentation tank 3, and the supernatant overflows through the overflow port 3.2, enters the overflow pipe 3.6, and then enters the bottom of the microbial fuel cell type artificial wetland unit 4 through the water inlet 4.1.

[0041] A water inlet 4.1 is provided at the bottom of the microbial fuel cell type artificial wetland unit 4. A water distribution layer 4.2, a first packing layer 4.3, a bioanode 4.4, a second packing layer 4.5, an electrochemical cathode 4.6 are provided inside the microbial fuel cell type artificial wetland unit 4 from bottom to top, and finally a wetland plant 4.7 planted on the top of the electrochemical cathode 4.6. The bioanode 4.4 and the electrochemical cathode 4.6 of the microbial fuel cell type artificial wetland unit 4 are connected to the energy storage power supply system 5 through a copper wire. Among them, the water distribution layer 4.2 is filled with pebbles to make the water inflow stable and uniform. The first packing layer 4.3 is filled with a mixture of ceramsite and gravel mixed in a mass ratio of 1:1; the bioanode 4.4 is filled with magnetite and fixed in a closed mesh structure made of a titanium mesh box and a titanium mesh cover; the anode is a carrier for microorganisms to attach, but it will exchange with the water phase. A large number of microorganisms with electricity generation and iron reduction functions can be detected in the anode effluent, and it can be used as an inoculation source. The second packing layer 4.5 is filled with a mixture of ceramsite and gravel in a mass ratio of 1:1; the electrochemical cathode 4.6 is filled with magnetite; the plants planted above the electrochemical cathode 4.6 include canna or reeds and other plants with well-developed root systems, with a planting density of 10 plants / m 2, the water inlet is from bottom to top; the roots of plants secrete oxygen and also have a certain function of absorbing organic pollutants. The anode outlet water of the microbial fuel cell type artificial wetland unit 4 can be regulated by the regulating valve 4.8 through the pipeline 4.9, and enter the iron sludge reduction unit 1 through the water inlet 1.5, providing the iron sludge reduction unit 1 with microorganisms with electricity generation and iron reduction functions. When it is not necessary to provide the iron sludge reduction unit 1 with microorganisms with electricity generation and iron reduction functions, the regulating valve 4.8 is closed, and the outlet water flows out through the electrochemical cathode 4.6.

[0042] like Figure 2 As shown, the energy storage power supply system 5 includes a battery, a controller, a solar panel and a power supply circuit. Part of the electric energy generated by the solar panel is converted into direct current of the voltage required by the electric Fenton oxidation zone 2 by the controller, and is transmitted to the electric Fenton oxidation zone 2 through the power supply circuit; the other part of the electric energy is converted into direct current of the voltage required by the battery by the controller and stored in the battery. The battery stores the direct current from the microbial fuel cell type artificial wetland unit 4 and the direct current converted by the controller from the electric energy of the solar panel. When the solar panel cannot supply power, the direct current in the battery is converted into direct current of the voltage required by the electric Fenton oxidation zone 2 by the controller and transmitted to the electric Fenton oxidation zone 2 through the power supply circuit.

[0043] Example 2 Method for treating sewage using an electro-Fenton sewage treatment system

[0044] according to Figure 3 The steps shown are for sewage treatment.

[0045] (1) Acid dye wastewater enters the iron sludge reduction unit 1 from the water inlet 1.1, wherein the iron sludge reduction unit 1 is an anaerobic environment. Through the action of the agitator 1.4, the iron in the anaerobic iron sludge contained in the iron sludge reduction unit 1 is dissolved; under anaerobic conditions, the microorganisms with power generation and iron reduction functions enriched in the iron sludge reduction unit 1 convert the adsorbed and dissolved Fe in the anaerobic iron sludge into 3+ Reduction to Fe 2+ , providing Fe for the subsequent electro-Fenton oxidation zone 2 2+ , and Fe 2+ The effluent, Fe 2+ The concentration is 206mg / L; the iron sludge reduction unit Fe 2+ The generation rate is 8.3 mg / L·h, which provides sufficient iron source for the electro-Fenton unit; at the same time, the acid dye wastewater undergoes anaerobic hydrolysis and acidification, which improves the biodegradability of the acid dye wastewater and provides sufficient organic carbon source for microorganisms with power generation and iron reduction functions; at the same time, the iron sludge undergoes anaerobically digested in the iron sludge reduction unit 1, which greatly reduces the amount of iron sludge and reduces the sludge treatment cost of the subsequent electro-Fenton unit;

[0046] (2) The Fe contained 2+ The effluent passes through the outlet 1.2, and in a step-by-step manner, carries dissolved oxygen through multiple low-level water collection tanks 2.1. The height difference between the tanks is used to allow the water to contact with the air and be oxygenated during the uniform fall, eliminating the power consumption of the blower required for aeration, thereby greatly reducing operating costs, providing sufficient oxygen for the electro-Fenton unit, and effectively increasing the amount of H2O2 generated by the electro-Fenton unit. The contact between water and air is fully strengthened by step-by-step falls, and more dissolved water in the water collection tank is carried through valve 2.2 into the electro-Fenton reaction zone 2, and is initially degraded to produce a large number of small molecular compounds; the sewage is fully in contact with the air during the fall, and dissolved oxygen is provided to the electro-Fenton reaction zone 2 by means of waterfall aeration; H2O2 and Fe are generated in situ 2+ The Fenton reaction generates ·OH with strong oxidizing properties, which helps to break the ring structure of the acid dye macromolecules, achieve dye decolorization, and improve the biodegradability of acid dye wastewater; the generation rate of hydrogen peroxide is 5.2 mg / L·h;

[0047] (3) The wastewater after preliminary degradation enters the coagulation and sedimentation zone 3 through the outlet 2.3 for coagulation and sedimentation to further remove insoluble organic matter and soluble iron elements, forming iron sludge and supernatant;

[0048] (4) The iron sludge in step (3) enters the sludge discharge pipe 3.4 through the sludge outlet 3.3, and is then sent to the sludge inlet 1.3 at the bottom of the iron sludge reduction unit 1 by the sludge pump 3.5 to enter the next cycle; wherein the iron sludge contains a large number of microorganisms with electricity generation and iron reduction functions;

[0049] (5) In step (3), the supernatant passes through the overflow port 3.2, enters the overflow pipe 3.6, and then enters the bottom of the microbial fuel cell type artificial wetland unit 4 through the water inlet 4.1. The microorganisms with power generation and iron reduction functions use the iron oxide of the anode as an electron acceptor, release electrons by oxidizing organic matter, and transfer electrons to the anode magnetite through the heterometallic metal reduction, accelerating the degradation of organic matter while generating electricity and enriching themselves quickly. After the water flow is purified by the plants in the cathode layer, it is discharged through the water outlet 4.6; the electricity is converted into direct current by the energy storage power supply system 5 to supply the Fenton oxidation zone 2 for use. In addition, a large number of small molecule compounds produced in step (2) are rapidly utilized by microorganisms with electricity generation and iron reduction functions, greatly improving the output power of the battery of the microbial fuel cell type artificial wetland unit 4; moreover, the filtering and interception effect of the artificial wetland can intercept pollutants; the high-density plants planted in the wetland can use their developed root systems to adsorb pollutants in the water, and the cathode wetland plants can also remove pollutants through root oxygen secretion; the anode effluent of the microbial fuel cell type artificial wetland unit 4 can be regulated by the regulating valve 4.8 through the pipeline 4.9 and enter the anaerobic iron sludge reduction unit through the water inlet 1.5, so as to quickly supplement the iron sludge reduction unit 1 with microorganisms with electricity generation and iron reduction functions;

[0050] (6) The electric energy stored in the battery is converted into the alternating current required by the electro-Fenton oxidation zone 2 in the form of direct current by the controller, and is transmitted to the electro-Fenton oxidation zone 2 through the power supply circuit for the next round of reaction.

[0051] In this embodiment, when the relative abundances of Geobacter sulfurreducens PCA, Desulfovibrioferrophilus IS5 and Shewanella onedensis MR-1 in the iron sludge reduction unit are 34%, 15% and 6%, respectively, the removal efficiency of acid red B dye in the entire treatment process reaches 97%, and the removal efficiency of COD reaches 92%.

[0052] Example 3 Method for treating sewage using an electro-Fenton sewage treatment system

[0053] The operation of Example 2 was repeated, except that the abundance ratios of the three microorganisms Geobactersulfurreducens PCA, Desulfovibrio ferrophilus IS5 and Shewanella onedensis MR-1 with electricity-generating and iron-reducing functions in the iron sludge reduction unit 1 were changed to 26%, 10% and 3%, respectively. The removal rate of acid red B dye in the whole treatment process reached 93%, and the removal rate of COD reached 86%. 2+The generation rate of hydrogen peroxide in the electro-Fenton oxidation zone 2 is 6.2 mg / L·h, and the generation rate of hydrogen peroxide in the electro-Fenton oxidation zone 2 is 4.8 mg / L·h.

[0054] Example 4 Method for treating sewage using an electro-Fenton sewage treatment system

[0055] The operation of Example 2 was repeated, except that the abundance ratios of the three microorganisms Geobactersulfurreducens PCA, Desulfovibrio ferrophilus IS5 and Shewanella onedensis MR-1 with electricity-generating and iron-reducing functions in the iron sludge reduction unit 1 were changed to 20%, 7% and 1%, respectively. The removal rate of acid red B dye in the whole treatment process reached 87%, and the removal rate of COD reached 82%. 2+ The generation rate of hydrogen peroxide in the electro-Fenton oxidation zone 2 is 4.2 mg / L·h, and the generation rate of hydrogen peroxide in the electro-Fenton oxidation zone 2 is 3.4 mg / L·h.

Claims

1. An electro-Fenton wastewater treatment system, comprising an iron sludge reduction unit (1) for reducing iron sludge, an electro-Fenton oxidation zone (2), a coagulation and sedimentation zone (3), and an energy storage and power supply system (5) connected to the electro-Fenton oxidation zone (2), characterized in that: It also includes a microbial fuel cell type artificial wetland unit (4) connected to the coagulation sedimentation area (3) and the energy storage power supply system (5) respectively; the microbial fuel cell type artificial wetland unit (4) is connected to the coagulation sedimentation area (3) through an overflow pipe (3.6); the microbial fuel cell type artificial wetland unit (4) is provided with a water distribution layer (4.2), a first filler layer (4.3), a bioanode (4.4), a second filler layer (4.5) and an electrochemical cathode (4.6) from bottom to top; microorganisms with electricity generation and iron reduction functions are attached to the bioanode (4.4); the bioanode (4.4) and the electrochemical cathode (4.6) are filled with magnetite; the microorganisms with electricity generation and iron reduction functions include Geobacter sulfurreducens PCA, Desulfovibrio ferrophilus IS5 and Shewanella onedensis One or more of MR-1; Geobacter sulfurreducens The relative abundance of PCA was 20-34%; Desulfovibrio ferrophilus The relative abundance of IS5 was 7-15%; Shewanella onedensis The relative abundance of MR-1 is 1~6%.

2. The electro-Fenton wastewater treatment system according to claim 1, characterized in that: The iron sludge reduction unit (1) is provided with a water inlet (1.1) and a water outlet (1.2), and contains an agitator (1.4) therein; the bottom of the iron sludge reduction unit (1) is also provided with a pipeline (4.9) for iron sludge to pass through the mud inlet (1.3) and connected to the microbial fuel cell type artificial wetland unit (4).

3. The electro-Fenton wastewater treatment system according to claim 1, characterized in that: A low-level water collection tank (2.1) is provided between the electro-Fenton oxidation zone (2) and the iron sludge reduction unit (1); an anode (2.4) and a cathode (2.5) are provided inside the electro-Fenton oxidation zone (2), and a water inlet regulating valve (2.2) and a water outlet hole (2.3) for regulating the amount of wastewater are provided on the side wall.

4. The electro-Fenton wastewater treatment system according to claim 1, characterized in that: The side wall of the coagulation and sedimentation zone (3) is provided with a water inlet regulating valve (3.1) connected to the water outlet hole (2.3); the bottom of the coagulation and sedimentation zone (3) is provided with a mud outlet (3.3), the mud outlet (3.3) is connected to the mud inlet (1.3) via a mud discharge pipe (3.4), and a mud pump (3.5) is provided on the mud discharge pipe (3.4); the side wall of the coagulation and sedimentation zone (3) is also provided with an overflow port (3.2).

5. The electro-Fenton wastewater treatment system according to claim 1, characterized in that: The energy storage and power supply system (5) comprises a battery, a controller, a solar panel and a power supply circuit connected to the electro-Fenton oxidation zone (2); the battery, the controller and the power supply circuit are connected in sequence; the solar panel is connected to the controller; the controller converts the electric energy generated by the solar panel into direct current for storage in the battery; the direct current stored in the battery is transmitted to the electro-Fenton oxidation zone (2) via the power supply circuit.

6. A method for treating wastewater using the electro-Fenton wastewater treatment system according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Wastewater enters the iron sludge reduction unit (1) containing microorganisms with power generation and iron reduction functions from the water inlet (1.1), so that the Fe in the iron sludge is 3+ The wastewater is then pre-treated by anaerobic degradation using the microorganisms in the iron sludge that have the functions of iron reduction and electricity production, thus obtaining Fe 2+ of wastewater; (2) Step (1) containing Fe 2+ The wastewater passes through the low-level water collection tank (2.1) in a stepped waterfall manner and enters the electro-Fenton oxidation zone (2) for Fenton reaction to obtain wastewater that has undergone preliminary degradation; (3) The wastewater that has undergone preliminary degradation in step (2) enters the coagulation and sedimentation zone (3) through the outlet hole (2.3) for coagulation and sedimentation to form iron sludge and supernatant; (4) The iron sludge in step (3) enters the sludge discharge pipe (3.4) through the sludge outlet (3.3), and is then sent to the sludge inlet (1.3) at the bottom of the iron sludge reduction unit (1) by the sludge pump (3.5) to enter the next cycle; (5) The supernatant in step (3) passes through the overflow port (3.2) and enters the overflow pipe (3.6), and then enters the bottom of the microbial fuel cell type artificial wetland unit (4) through the water inlet (4.1). The microorganisms with iron reduction and electricity generation functions attached to the bioanode (4.4) oxidize and remove organic matter in the supernatant, generate electricity, and obtain anode effluent; (6) The anode effluent in step (5) enters the anaerobic iron sludge reduction unit through the water inlet (1.5), and supplements the iron sludge reduction unit (1) with microorganisms having iron reduction and electricity generation functions; (7) The electric energy in step (5) is supplied to the electro-Fenton oxidation zone (2) in the form of direct current via the battery and is then transmitted to the electro-Fenton oxidation zone (2) via the power supply circuit for the next round of reaction.

7. The method according to claim 6, characterized in that: The electrogenic microorganisms in step (5) include Geobacter sulfurreducens PCA , Desulfovibrio ferrophilus IS5 or Shewanella onedensis One or more of MR-1.

8. The electro-Fenton wastewater treatment system according to claim 7, characterized in that: Said Geobacter sulfurreducens The relative abundance of PCA was 20-34%; Desulfovibrio ferrophilus The relative abundance of IS5 was 7-15%; Shewanella onedensis The relative abundance of MR-1 is 1~6%.

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