Wastewater treatment equipment

Abstract

This application relates to the field of wastewater treatment technology, and in particular to a wastewater treatment device. When this device treats wastewater, the wastewater undergoes a Fenton reaction in a Fenton reactor for initial degradation, and is then discharged to the cathode chamber. Iron sludge deposited during the Fenton reaction is discharged to the anode chamber. In the cathode chamber, the wastewater undergoes secondary degradation under the catalytic action of sulfate-reducing bacteria to remove SO4 from the wastewater. 2‑ The wastewater, after secondary degradation, is discharged into the anode chamber where it undergoes a tertiary degradation under the catalysis of iron-based anaerobic ammonia-oxidizing bacteria to remove ammonia nitrogen and ferric hydroxide from the iron sludge. Cations and electrons in the electrolyte within the anode and cathode chambers exchange through a cation exchange membrane, promoting the removal of ammonia nitrogen (NH4+). + -N) and SO4 2‑ The simultaneous removal of these substances allows the reactions in both the cathode and anode chambers to proceed smoothly.

Description

Technical Field

[0001] This application relates to the field of industrial wastewater treatment technology, and in particular to a wastewater treatment device. Background Technology

[0002] With the rapid development of industrial production, the discharge of highly hazardous and recalcitrant industrial wastewater is also increasing daily. The treatment of high-concentration, recalcitrant industrial wastewater has become a recognized challenge in the wastewater treatment industry both domestically and internationally. Industrial wastewater, such as dyeing and printing wastewater, pharmaceutical wastewater, and papermaking wastewater, is mostly recalcitrant, characterized by high toxicity and poor biodegradability.

[0003] Industrial wastewater contains highly complex pollutants, most of which are highly toxic. If discharged directly into water bodies without treatment, it will cause incalculable harm to aquatic plants, animals, and human health. Furthermore, with the development of industrial production, new synthetic organic compounds are constantly entering industrial wastewater. Large quantities of these new organic compounds pose a significant threat to human organs and survival. Biochemical treatment of this type of wastewater effectively inhibits the activity of microorganisms.

[0004] To effectively treat recalcitrant wastewater, advanced green and environmentally friendly pretreatment technologies must be adopted to reduce the toxicity of pollutants, improve its biodegradability, create conditions for biological treatment, and ultimately achieve compliant discharge. Currently, the wastewater treatment efficiency of wastewater treatment equipment needs improvement. Summary of the Invention

[0005] This application provides a wastewater treatment device that can improve wastewater treatment efficiency.

[0006] This application provides a wastewater treatment device comprising: a Fenton reactor having a first drain outlet and a first sludge outlet; a cathode reactor including a cathode electrode, a cathode chamber, and a second inlet and a second drain outlet connected to the cathode chamber, the second inlet being connected to the first drain outlet via a pipeline, the cathode chamber containing sulfate-reducing bacteria; and an anode reactor including an anode electrode, an anode chamber, and a third inlet, a third drain outlet, and a third sludge inlet connected to the anode chamber, the third inlet being connected to the second drain outlet via a pipeline, the third sludge inlet being connected to the first sludge outlet via a pipeline, a cation exchange membrane being disposed between the cathode chamber and the anode chamber, the anode chamber containing iron-based anaerobic ammonia-oxidizing bacteria.

[0007] During wastewater treatment, the anode reactor and the cathode reactor are in operation. The wastewater to be treated undergoes a Fenton reaction in the Fenton reactor for initial degradation, and is then discharged from the first drain outlet and enters the cathode chamber through the second inlet. The iron sludge generated during the Fenton reaction is discharged from the first sludge discharge outlet and fed into the anode chamber through the third sludge inlet. The wastewater in the cathode chamber undergoes a second degradation under the catalysis of sulfate-reducing bacteria, and is then discharged from the second drain outlet and enters the anode chamber through the third inlet. Under the catalysis of iron-based anaerobic ammonia-oxidizing bacteria, it undergoes a third degradation. The cations in the electrolyte in the anode chamber and the cathode chamber are exchanged through the cation exchange membrane.

[0008] In the embodiments of this application, the wastewater to be treated undergoes a Fenton reaction in a Fenton reactor for primary degradation, and is then discharged into the cathode chamber. The iron sludge deposited during the Fenton reaction is discharged into the anode chamber. In the cathode chamber, the wastewater after primary degradation undergoes secondary degradation under the catalytic action of sulfate-reducing bacteria to remove SO4 from the wastewater. 2- The wastewater, after secondary degradation, is discharged into the anode chamber where it undergoes a tertiary degradation under the catalysis of iron-based anaerobic ammonia-oxidizing bacteria to remove ammonia nitrogen and ferric hydroxide from the iron sludge. Cations and electrons in the electrolyte within the anode and cathode chambers exchange through a cation exchange membrane, promoting the removal of ammonia nitrogen (NH4+). + -N) and SO4 2- The simultaneous removal of these substances allows the reactions in both the cathode and anode chambers to proceed smoothly.

[0009] In some embodiments, the anode and cathode reaction electrodes comprise a Fe3O4 / carbon felt composite material; the Fe3O4 / carbon felt composite material is prepared as follows: carbon felt is immersed in NaOH solution to obtain a first mixture, and the first mixture is subjected to ultrasonic treatment; FeSO4, Na2S2O3 and water are thoroughly mixed to obtain a second mixture; after the first and second mixtures are thoroughly mixed, they are placed in a hydrothermal reaction vessel for hydrothermal reaction to load Fe3O4 onto the carbon felt, thereby obtaining the Fe3O4 / carbon felt composite material.

[0010] In some embodiments, the mass ratio of FeSO4 to Na2S2O3 ranges from (1:1) to (1.2:1).

[0011] In some embodiments, the ultrasonic treatment time is 20 min to 30 min, the hydrothermal reaction temperature is 120 °C, and the hydrothermal reaction time is 12 h.

[0012] In some embodiments, the anode reaction electrode and the cathode reaction electrode include a first carbon fiber prepreg layer, a polytetrafluoroethylene film layer, the Fe3O4 / carbon felt composite material layer, and a second carbon fiber prepreg layer arranged sequentially.

[0013] In some embodiments, the anode reactor further includes an anode aeration disc disposed near the bottom of the anode chamber, the anode aeration disc being used to aerate the water in the anode chamber with nitrogen gas;

[0014] The cathode reactor also includes a cathode aeration disc, which is located near the bottom of the cathode chamber and is used to aerate the water in the cathode chamber with nitrogen.

[0015] In some embodiments, the Fenton reaction tower includes a first-zone aeration disc, a first-zone reaction chamber, a second-zone aeration disc, a second-zone reaction chamber, a solid-liquid separation net, and a gas-liquid separation chamber arranged sequentially from the bottom to the top of the Fenton reaction tower. The gas-liquid separation chamber is connected to the first drain outlet. The first-zone aeration disc and the second-zone aeration disc are used to aerate the liquid and solid fluids in the first-zone reaction chamber and the second-zone reaction chamber with nitrogen, respectively. The solid-liquid separation net is used to allow liquids and gases to pass through while preventing solids from passing through.

[0016] In some embodiments, the Fenton reaction tower is further provided with a reflux outlet and a reflux inlet, wherein the reflux inlet is connected to the first reaction chamber, the reflux outlet is connected to the second reaction chamber, the reflux inlet and the reflux outlet are connected by a reflux pipe, and the solid-liquid fluid in the second reaction chamber is returned to the first reaction chamber through the reflux pipe.

[0017] In some embodiments, the Fenton reaction tower further includes a reflux regulator disposed in the reflux pipe, the reflux regulator being used to regulate the hydraulic flow rate and pH value of the solid-liquid fluid in the reflux pipe.

[0018] In some embodiments, the anode reactor further includes an anode reference electrode, and the cathode chamber further includes a cathode reference electrode; the wastewater treatment equipment further includes a nitrogen generator and a controller, the nitrogen generator being connected to the cathode aeration disc, the anode aeration disc, the first-zone aeration disc, and the second-zone aeration disc via pipelines; the controller being communicatively connected to the anode reaction electrode, the anode reference electrode, the cathode reaction electrode, the cathode reference electrode, and the nitrogen generator; the controller is used to control the electrochemical reactions in the anode reactor and the cathode reactor by adjusting the potentials of the anode reaction electrode and the cathode reaction electrode, and to control the nitrogen aeration rate of the cathode aeration disc, the anode aeration disc, the first-zone aeration disc, and the second-zone aeration disc respectively via the nitrogen generator.

[0019] It should be understood that the description in the Summary of the Invention section is not intended to limit the key or essential features of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0021] Figure 1 These are schematic diagrams of the wastewater treatment equipment provided in some embodiments of this application;

[0022] Figure 2 These are schematic diagrams of the wastewater treatment equipment provided in other embodiments of this application;

[0023] Figure 3 This is a schematic flowchart illustrating the preparation method of Fe3O4 / carbon felt composite material provided in some embodiments of this application. Detailed Implementation

[0024] The principles and spirit of this disclosure will be described below with reference to several exemplary embodiments illustrated in the accompanying drawings. It should be understood that these specific embodiments are described merely to enable those skilled in the art to better understand and implement this disclosure, and are not intended to limit the scope of this disclosure in any way. In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0025] As used herein, the term "comprising" and similar terms should be understood as open inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "an embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects and are used only to distinguish the objects referred to, without implying a particular spatial order, temporal order, order of importance, etc., of the objects referred to.

[0026] Please see Figure 1 The wastewater treatment equipment 100 provided in this application embodiment includes: a Fenton reactor 10 and a microbial electrolysis cell (MEC) reactor 20 connected to the Fenton reactor 10 via pipeline. The Fenton reactor 10, also known as a Fenton fluidized bed reactor, is a device that utilizes the Fenton reaction to perform advanced oxidation treatment on the wastewater to be treated. After undergoing Fenton treatment in the Fenton reactor 10, the wastewater is fed into the MEC reactor 20, where electrochemically active bacteria further degrade harmful substances in the wastewater. The MEC reactor 20 promotes the growth and metabolism of electroactive microorganisms through appropriate electrical stimulation, causing changes in the microbial community structure and effectively enriching dominant bacterial species. Under appropriate electrical stimulation, the activity of microbial enzymes and cell membrane permeability are enhanced, thereby improving the degradation efficiency of nitrogen-containing wastewater by microorganisms. In the embodiments of this application, the electroactive microorganisms in the MEC reactor 20 include sulfate-reducing bacteria (SRB) and iron-based anaerobic ammonium oxidizing bacteria (AnAOB).

[0027] Specifically, the Fenton reactor 10 is used to perform Fenton treatment on the input wastewater to obtain wastewater after initial degradation. The Fenton reactor 10 is provided with a first drain outlet 11 and a first sludge discharge outlet 12, wherein the first drain outlet 11 is used to discharge the wastewater after initial degradation, and the first sludge discharge outlet 12 is used to discharge the iron sludge generated during the Fenton treatment process. The Fenton reactor 10 is also provided with a first inlet 19, which is used to input the wastewater to be treated into the Fenton reactor 10.

[0028] The MEC reactor 20 specifically includes a cathode reactor 21 and an anode reactor 22. The anode reactor 22 and the cathode reactor 21 can be connected by wires and a power source. Applying voltage to the anode reactor 22 and the cathode reactor 21 via the power source puts them into operation.

[0029] The cathode reactor 21 includes a second inlet 211, a second outlet 212, a cathode chamber 213, and a cathode electrode 214. The second inlet 211 and the second outlet 212 are connected to the cathode chamber 213. The second inlet 211 is connected to the first outlet 11 via a pipeline. The second inlet 211 is used to input the wastewater discharged from the first outlet 11 after primary degradation into the cathode chamber 213, and the second outlet 212 is used to discharge the wastewater after secondary degradation in the cathode chamber 213. The cathode chamber 213 contains SRB bacteria; the SRB bacteria accumulate on the surface of the cathode electrode 214 and form an SRB biofilm.

[0030] The anode reactor 22 includes a third inlet 221, a third sludge inlet 222, an anode chamber 223, and an anode electrode 224. The third inlet 221 and the third sludge inlet 222 are connected to the anode chamber 223. The third inlet 221 is connected to a second outlet 212 via a pipeline, and is used to input the further degraded wastewater discharged from the second outlet 212. The third sludge inlet 222 is connected to a first sludge outlet 12 via a pipeline, and is used to input the iron sludge discharged from the first sludge outlet 12 into the anode chamber 223. The anode chamber 223 contains iron-based AnAOB bacteria; the iron-based AnAOB bacteria accumulate on the surface of the anode electrode 224 and form an AnAOB biofilm.

[0031] A cation exchange membrane 23 is provided between the cathode chamber 213 and the anode chamber 223. The electrolyte in the cathode chamber 213 and the electrolyte in the anode chamber 223 can exchange cations (such as ferric ions, ferrous ions and hydrogen ions) and electrons through the cation exchange membrane 23.

[0032] When wastewater is treated in the wastewater treatment equipment 100, the anode reactor 22 and the cathode reactor 21 are in operation. The wastewater to be treated undergoes a Fenton reaction in the Fenton reactor tower 10 for initial degradation, and is then discharged from the first drain outlet 11 and enters the cathode chamber 213 through the second inlet 211. The iron sludge deposited during the Fenton reaction is discharged from the first sludge discharge outlet 12 and fed into the anode chamber 223 through the third sludge inlet 222. After the initial degradation in the cathode chamber 213, the wastewater undergoes a secondary degradation under the catalysis of SRB bacteria, and is then discharged from the second drain outlet 212 and enters the anode chamber 223 through the third inlet 221 for a tertiary degradation under the catalysis of iron-based AnAOB bacteria. The cations and electrons in the wastewater in the anode chamber 223 and cathode chamber 213 are exchanged through the cation exchange membrane 23.

[0033] When the wastewater to be treated undergoes Fenton treatment in Fenton reactor 10, ferrous ions (Fe)... 2+Ferrous sulfate reacts with hydrogen peroxide (H₂O₂) to generate highly oxidizing hydroxyl radicals (OH·). These OH· radicals oxidize the recalcitrant macromolecular organic matter in the wastewater, converting it into easily degradable small organic molecules. Fenton treatment converts a large amount of organic nitrogen in the wastewater into ammonia nitrogen, reducing the chemical oxygen demand (COD). During the Fenton treatment process, Fe... 2+ It will be oxidized into iron ions (Fe). 3+ During the pH adjustment process, a large amount of iron sludge containing ferric hydroxide is generated. Currently, this iron sludge is often treated as hazardous solid waste, which increases the cost of subsequent treatment and has become one of the important factors restricting the promotion and development of Fenton technology.

[0034] In the embodiments of this application, Fenton pretreatment reduces the biotoxicity and COD of the wastewater to be treated, converts a large amount of organic nitrogen into ammonia nitrogen, and improves the biochemical effect; wherein, ammonia nitrogen refers to free ammonia (NH3) and ammonium ions (NH4) in the wastewater. + Nitrogen exists in the form of ). Furthermore, by using only a Fenton reaction device for preliminary treatment of the wastewater, the cost of the Fenton reaction can be reduced.

[0035] After Fenton treatment in Fenton reactor 10, the wastewater discharged after primary degradation contains sulfate and biodegradable small-molecule organic matter. The available organic matter in the wastewater can serve as a carbon source for SRB bacteria, providing them with the energy needed for growth and metabolism. When the primary-degraded wastewater is discharged into cathode chamber 213, the SRB bacteria in chamber 213 use the sulfate in the primary-degraded wastewater as a sulfur cycle substrate, converting the sulfate into a large amount of elemental sulfur precipitate and a small amount of hydrogen sulfide gas, thus reducing the amount of reagents required and lowering operating costs. Simultaneously, the biodegradable small-molecule organic matter in the wastewater in cathode chamber 213 can also provide energy for the growth and metabolism of SRB bacteria, activating the generation of highly oxidizing ammonium persulfate (APS). APS further removes organic pollutants from the wastewater, forming a co-metabolism; this reduces both sulfate and COD in the wastewater.

[0036] After the initial degradation, the wastewater undergoes secondary degradation in the cathode chamber 213 before being discharged into the anode chamber 223. Additionally, the iron sludge generated during the Fenton treatment process is also discharged into the anode chamber 223. The iron-based AnAOB bacteria community within the anode chamber 223 feeds on the Fe in the iron sludge. 3+ Iron-based anaerobic ammonium oxidation (AAO) acts as a substrate for denitrification; iron-based AnAOB bacteria convert Fe... 3+ Converted to Fe 2+Nitrate-dependent ferrous oxidation (NDFO) is then performed to remove nitrogen and generate nitrogen gas. The generated nitrite is then used for anaerobic ammonia oxidation to remove nitrogen and generate nitrogen gas. The anaerobic ammonia oxidation reaction and the NDFO reaction are coupled using iron sludge produced by the Fenton reaction. This application's embodiments address the problems of slow growth and long start-up time of AnAOB through microbial electrochemical technology, thereby improving the degradation efficiency of anaerobic ammonia oxidizing microorganisms for nitrogen-containing wastewater.

[0037] When the wastewater is degraded in the cathode chamber 213 and the anode chamber 223, the wastewater in the cathode chamber 213 and the anode chamber 223 undergoes hydrogen ion and Fe ion exchange through the cation exchange membrane 23. 2+ Fe 3+ The exchange of electrons and other substances ensures the SRB reaction and anaerobic ammonium oxidation; for example, Fe in anode chamber 223 2+ The microorganisms can enter the cathode chamber 213 and react with sulfur ions within the chamber to generate ferrous sulfide precipitate. In the embodiments of this application, the heterotrophic process of the microorganisms involves the supply of organic matter. The microorganisms can utilize humic substances for electron shuttle, enabling electron transfer between microbial cells and long-distance minerals. In the absence of carbon for electron transfer, the SRB can receive electrons from the cathode reaction electrode 214 to reduce sulfur; ferrous ions are generated from ferric ions within the cathode chamber 213 to precipitate ferrous sulfide.

[0038] This embodiment utilizes the "iron sludge" containing ferric hydroxide generated during the Fenton treatment process as the nitrogen cycling substrate for the iron-based anaerobic ammonia-oxidizing bacteria community in the anode chamber 223, which can reduce operating costs and lower sludge disposal and reagent dosage expenses. Through the nitrogen cycling of the iron-based anaerobic ammonia-oxidizing bacteria community, the large amount of ammonia nitrogen generated during the Fenton treatment process is denitrified and converted into nitrogen gas, achieving high-efficiency denitrification. This embodiment can reduce the footprint of the wastewater treatment equipment 100 and reduce operating costs.

[0039] In the embodiments of this application, the wastewater in the anode chamber 223 and the cathode chamber 213 undergoes cation and electron exchange through the cation exchange membrane 23, promoting the reduction of ammonia nitrogen (NH4+). + -N) and SO4 2- The simultaneous removal of these substances ensures the smooth progress of the reactions within the cathode chamber 213 and the anode chamber 223. This embodiment utilizes an intermittent microcurrent scheme to achieve high bioelectrocatalytic induction enhancement efficiency, improve the metabolism of SRB and AnAOB, shorten the iteration process, and facilitate the formation of granular sludge.

[0040] The embodiments of this application utilize facultative anaerobic bacteria in the SRB bacterial community to consume oxygen in the water, ensuring an extremely low oxygen content environment for the iron-based anaerobic ammonia oxidation in the anode reactor 22, and reducing the COD and sulfate content in the water, which improves the efficiency of the iron-based anaerobic ammonia oxidation reaction. The formation of a low COD and sulfate environment greatly increases the efficiency of the iron-based anaerobic ammonia oxidation.

[0041] Specifically, please refer to Figure 2 In some embodiments, the Fenton reactor 10 includes a first-zone aeration plate, a first-zone reaction chamber 14, a second-zone aeration plate, a second-zone reaction chamber 16, a solid-liquid separation net 17, and a gas-liquid separation chamber 18 arranged sequentially from the bottom to the top of the Fenton reactor 10. The gas-liquid separation chamber 18 is connected to the first drain outlet 11. A first inlet 19 is opened on the side of the Fenton reactor 10 near the bottom of the tower, and the first inlet 19 is used to input the wastewater to be treated into the first-zone reaction chamber 14.

[0042] In some embodiments, the industrial wastewater needs to be pretreated before being fed into the Fenton reactor 10. The pretreatment method includes pH adjustment, for example, adjusting the pH of the wastewater to be treated to 3-4 in advance to improve the degradation rate of organic matter.

[0043] In some embodiments, a first sludge discharge port 12 is located on the side of the Fenton reaction tower 10 near the bottom, and is used to discharge iron sludge deposited at the bottom of the Fenton reaction tower 10 during the Fenton treatment process. A first drain port 11 and a first exhaust port 110 are located on the side of the Fenton reaction tower 10 near the top; the first drain port 11 and the first exhaust port 110 communicate with the gas-liquid separation chamber 18. The first exhaust port 110 is used to discharge gas from the Fenton reaction tower 10. Specifically, the first exhaust port 110 may be located at the top of the Fenton reaction tower 10.

[0044] In some embodiments, the wastewater treatment equipment 100 further includes a first nitrogen generator 60, the outlet of which is connected to the pipelines of the first-zone aeration disc and the second-zone aeration disc, respectively. The nitrogen generated by the first nitrogen generator 60 is released through the first-zone aeration disc and the second-zone aeration disc to aerate the solid-liquid mixture in the Fenton reactor 10, thereby fluidizing the solid-liquid mixture.

[0045] Specifically, in some embodiments, the first-zone aeration disc includes a first-stage aeration disc 131 and a second-stage aeration disc 132, which are connected to the first-stage aeration disc 131 via pipelines. The second-stage aeration disc 132 is used to divert nitrogen supplied by the first-stage aeration disc 131. In other embodiments, the second-zone aeration disc includes a second-stage aeration disc 151 and a second-stage aeration disc 152, which are connected to the first-stage aeration disc 151 via pipelines. The second-stage aeration disc 152 is used to divert nitrogen supplied by the first-stage aeration disc 151.

[0046] In this embodiment, the combined use of primary aeration disc 131 and secondary aeration disc 132 in zone one (or primary aeration disc 151 and secondary aeration disc 152 in zone two) allows for graded regulation of nitrogen emissions. The fluidized bed hydraulics are adjusted based on the aeration volume, making the fluidization pattern controllable. Furthermore, the primary aeration disc 151 in zone two allows fluidized solid particles to pass through; the secondary aeration disc 152 in zone two has a high pore density, allowing only water to pass through, thus preventing the flow of solid single-phase material between reaction chamber 14 in zone one and reaction chamber 16 in zone two. By setting up the secondary aeration discs, the first and second reaction chambers are separated, and sludge control is achieved, making the fluidization process more easily adjustable.

[0047] In some embodiments, the Fenton reaction tower 10 is further provided with a separation blocker 111, which is disposed between the secondary aeration disc and the tower wall of the Fenton reaction tower 10, and is used to prevent the solid, liquid and gas phases from flowing between the primary reaction chamber 14 and the secondary reaction chamber 16.

[0048] In some embodiments, the Fenton reaction tower 10 also has a reflux outlet and a reflux inlet, wherein the reflux inlet is connected to the first reaction chamber 14, the reflux outlet is connected to the second reaction chamber 16, and the reflux inlet and reflux outlet are connected by a reflux pipe 112. The solid-liquid mixture at the upper end of the second reaction chamber 16 is returned to the bottom of the first reaction chamber 14 through the reflux pipe 112.

[0049] In the embodiments of this application, a two-stage fluidized bed is formed by an aeration disc in zone one, a reaction chamber 14 in zone one, an aeration disc in zone two, and a reaction chamber 16 in zone two. The two-stage fluidized bed configuration, along with the circulating flow of fluid through the return pipe 112, results in a longer hydraulic retention time, more thorough contact between the industrial wastewater and the Fenton reagent, improving the efficiency and completeness of the Fenton reaction. Furthermore, the liquid can be re-tested and its acidity adjusted as it passes through the return pipe 112; therefore, the Fenton treatment process is more controllable and easier to operate.

[0050] In some embodiments, the Fenton reactor 10 further includes a reflux regulator 113 disposed in the reflux pipe 112. The reflux regulator 113 is used to regulate the hydraulic flow rate and pH value of the fluid in the reflux pipe 112.

[0051] In some embodiments, the working process of the Fenton reactor 10 is as follows: The industrial wastewater to be treated enters the first reaction chamber 14 through the first inlet 19 and undergoes a heterogeneous Fenton reaction in the first reaction chamber 14; simultaneously, nitrogen generated by the first nitrogen generator 60 is released through the first aeration disc to fluidize the liquid-solid fluid within the first reaction chamber 14. After the industrial wastewater undergoes preliminary reaction in the first reaction chamber 14, the liquid-solid fluid within the first reaction chamber 14 is propelled by hydraulic force through the second aeration disc and enters the second reaction chamber 16; simultaneously, nitrogen generated by the first nitrogen generator 60 fluidizes the solid-liquid fluid within the second reaction chamber 16 through the second aeration disc. The industrial wastewater undergoes further reaction in the second reaction chamber 16. The fluid in the second reaction chamber 16 near the solid-liquid separation net 17 enters the first reaction chamber 14 through the external return pipe 112, thereby undergoing hydraulic enhancement through the external return pipe 112. The hydraulic flow rate and pH value of the water in the external return pipe 112 can also be adjusted by the return regulator 113. After the industrial wastewater has reacted in the secondary reaction chamber 16, the gas and liquid in the mixture pass through the solid-liquid separation net 17 and enter the gas-liquid separation chamber 18; the gas entering the gas-liquid separation chamber 18 is discharged through the first exhaust port 110, and the liquid entering the gas-liquid separation chamber 18 is discharged through the first drain port 11. The iron sludge generated during the Fenton treatment process is deposited at the bottom of the Fenton reaction tower 10 and discharged through the first sludge discharge port 12.

[0052] In some embodiments, the wastewater treatment equipment 100 further includes an effluent regulator 30, which is connected to the Fenton reactor 10 and the cathode chamber reactor via pipelines. The effluent regulator 30 is used to adjust the pH value of the Fenton-treated industrial wastewater discharged from the first drain outlet 11, for example, adjusting the pH value to around 6. The Fenton-treated industrial wastewater discharged from the first drain outlet 11, after its pH value is adjusted by the effluent regulator 30, is then fed into the cathode chamber 213.

[0053] In some embodiments, the cathode reactor 21 further includes a cathode aeration disc 217. The cathode aeration disc 217 is disposed near the bottom of the cathode chamber 213. The cathode aeration disc 217 can be connected to a second nitrogen generator 70 via a pipeline. The cathode aeration disc 217 is used to aerate the water in the cathode chamber 213 with nitrogen gas. The nitrogen gas released by the cathode aeration disc 217 is used to strip oxygen and hydrogen sulfide from the wastewater in the cathode chamber 213. The gases in the cathode chamber 213, such as nitrogen gas, and the oxygen and hydrogen sulfide gases stripped by the nitrogen gas, are discharged through a second exhaust port 215. The hydraulic shear force generated by the nitrogen gas released by the cathode aeration disc 217 can maintain the stability of the biofilm content on the cathode reactor electrode 214 and assist the sludge in using iron as a nucleus to form sludge particles.

[0054] In some embodiments, the cathode reactor 21 is further provided with a second exhaust port 215, which is connected to the cathode chamber 213. The second exhaust port 215 is located on one side near the top of the cathode chamber 213 and is used to discharge the gas in the cathode chamber 213.

[0055] In some embodiments, the cathode reactor 21 is further provided with a second sludge discharge port 218, which is connected to the cathode chamber 213. The second sludge discharge port 218 is located on one side near the bottom of the cathode chamber 213 and is used to discharge iron sludge deposited at the bottom of the cathode chamber 213.

[0056] In some embodiments, the wastewater treatment equipment 100 further includes a sludge equalization tank 40, one end of which is connected to a first sludge discharge port 12, and the other end of which is connected to a third sludge inlet 222. The sludge equalization tank 40 is used to store iron sludge input from the first sludge discharge port 12. The iron sludge in the sludge equalization tank 40 is input to the anode chamber 223 through the third sludge inlet 222.

[0057] In some embodiments, the wastewater treatment equipment 100 further includes a sludge discharge tank 50, which is connected to the cathode chamber 213 and the sludge equalization tank 40, respectively. The sludge discharge tank 50 is used to store iron sludge input from the cathode chamber 213 and the sludge equalization tank 40. The iron sludge in the sludge equalization tank 40 is diverted to the sludge discharge tank 50 and the anode chamber 223.

[0058] In some implementations, the anode reactor 22 is also provided with a third drain outlet 225, which is connected to the anode chamber 223. The third drain outlet 225 is used to discharge the wastewater that has undergone three degradation processes in the anode chamber 223.

[0059] In some implementations, the anode reactor 22 is also provided with a third exhaust port 226, which is connected to the anode chamber 223. The third exhaust port 226 is located on one side near the top of the anode chamber 223 and is used to discharge the gas in the anode chamber 223.

[0060] In some embodiments, the anode reactor 22 further includes an anode aeration disc 227. The anode aeration disc 227 is disposed near the bottom of the anode chamber 223. The anode aeration disc 227 can be connected to a third nitrogen generator 80 via a pipeline. The anode aeration disc 227 is used to discharge nitrogen gas, which is used to strip oxygen from the electrolyte in the anode chamber 223. Gases in the cathode chamber 213, such as nitrogen gas and oxygen gas stripped by nitrogen gas, are discharged through a third exhaust port 226. The hydraulic shear force generated by the nitrogen gas released by the anode aeration disc 227 can maintain the stability of the biofilm content on the anode reaction electrode 224 and assist the sludge in forming sludge particles using iron as a nucleus.

[0061] In some embodiments, an ultra-black matte coating is also provided on the outer wall of the anode reactor 22. The ultra-black matte coating is used to prevent natural light from entering the anode chamber 223, thus avoiding adverse effects of natural light on the anaerobic ammonia oxidation reaction inside the anode chamber 223. For example, it prevents natural light from conducting heat to the anode chamber 223, ensuring the stability of the internal temperature of the anode chamber 223, allowing the microbial community to accelerate the reaction rate at a suitable temperature. Furthermore, the ultra-black matte coating is waterproof and resistant to high temperatures and corrosive substances.

[0062] In some embodiments, the anode reactor 22 and the anode reactor 22 adopt a double-layer insulation structure as the outer wall, and the cathode chamber 213 and the anode chamber 223 form a height difference, so that the water effluent from the cathode chamber 213 can flow naturally into the anode chamber 223.

[0063] In some embodiments, the cathode reactor 21 further includes a cathode reference electrode 216 disposed near the bottom of the cathode chamber 213. In other embodiments, the anode reactor 22 further includes an anode reference electrode 228 disposed near the bottom of the anode chamber 223.

[0064] In some embodiments, the microbial electrolysis reactor further includes an electrochemical workstation connected to the cathode reaction electrode 214, the cathode reference electrode 216, the anode reaction electrode 224, and the anode reference electrode 228. After data feedback, the electrochemical workstation displays and adjusts the electrode potential, current, biopotential, and power data according to the controller's instructions. The electrochemical workstation is an electronic instrument for controlling the potential difference between the working electrode and the reference electrode. By using performance parameters such as the potential obtained from the cathode reference electrode 216 and the anode reference electrode 228, the electrochemical workstation regulates the potential of the cathode reaction electrode 214 and the anode reaction electrode 224 to control the electrochemical reaction at the cathode reaction electrode 214 and the anode reaction electrode 224.

[0065] In some embodiments, the wastewater treatment equipment 100 further includes a controller connected to an electrochemical workstation. In other embodiments, the controller may also be connected to a nitrogen generator to control the aeration rate of the Fenton reactor 10, the cathode reactor 21, and / or the anode reactor 22. The nitrogen generator includes a first nitrogen generator 60, a second nitrogen generator 70, and / or a third nitrogen generator 80 connected together. The nitrogen generator blowout creates a later-stage anaerobic environment in the cathode and anode chambers, and different levels of nitrogen aeration are performed at each process stage to ensure high efficiency of the later-stage anaerobic ammonia oxidation reaction.

[0066] The controller enhances AnAOB metabolism by regulating the redox potential of the anode reaction electrode 224, and combines it with shear forces such as aeration and stripping to form anaerobic ammonia oxidation granular sludge, thereby improving the overall anaerobic ammonia oxidation efficiency.

[0067] The controller has basic control functions such as controlling and adjusting water intake, air intake, drainage, pH value, air volume, and sludge intake and discharge, as well as data processing. It also has functions such as abnormal information recording and feedback, electrochemical parameter adjustment, and electrochemical reset to restart the test state. The controller has functions of data and operation log acquisition, storage, processing, and output. It has alarm functions for reagent balance, abnormal information, instrument failure, and test result exceeding the standard.

[0068] In some embodiments, the anode reaction electrode and the cathode reaction electrode 214 comprise an Fe3O4 / carbon felt composite material; the preparation method of the Fe3O4 / carbon felt composite material is as follows:

[0069] Step a: Soak the carbon felt in NaOH solution to obtain a first mixture, and then subject the first mixture to ultrasonic treatment.

[0070] Carbon felt (CF), also known as carbon fiber felt, refers to a composite material made of carbon fiber. Carbon felt possesses advantages such as good chemical stability, high strength, good electrical conductivity, lightweight, and corrosion resistance. Step a specifically includes: weighing and dissolving NaOH in ultrapure water to obtain a NaOH solution. Immersing the treated carbon felt in the NaOH solution to obtain the first mixture, which is a mixture of carbon felt and NaOH solution. Sealing and sonicating the first mixture for 20-30 minutes allows the carbon felt to fully absorb the NaOH. Here, sealing and sonicating refers to placing the sample to be sonicated in a sealed container for ultrasonic treatment.

[0071] In some embodiments, the carbon felt needs to be cleaned before immersing it in NaOH solution. The cleaning method may specifically involve: ultrasonically cleaning the carbon felt three times with an organic solvent, then immersing the carbon felt in the organic solvent in a sealed container for a certain period of time. After immersion, the carbon felt is removed and ultrasonically cleaned with ethanol to remove oil stains from its surface and interior. The carbon felt cleaned with ethanol is then rinsed several times with distilled water and dried in an oven at 60–80°C for 6–12 hours.

[0072] Step b: Thoroughly mix FeSO4, Na2S2O3 and water to obtain a second mixture;

[0073] In this embodiment, FeSO4 and Na2S2O3 were weighed out in proportion and placed in the lining of a reaction vessel. A certain amount of ultrapure water was added, and the mixture was sealed and ultrasonically accelerated to dissolve the second mixture. The ultrasonically treated first mixture was then poured into the reaction vessel, and the vessel was sealed and ultrasonically mixed to ensure thorough mixing of the first and second mixtures.

[0074] In some embodiments, when the mass ratio of FeSO4 to Na2S2O3 is in the range of (1:1) to (1.2:1), the Fe3O4 / carbon felt composite material exhibits good performance and a high electrode reaction rate as an electrode material. To further improve the performance of the electrode material, the mass ratio of FeSO4 to Na2S2O3 can specifically be 1:1.

[0075] Step c: After thoroughly mixing the first mixture and the second mixture, place them in a hydrothermal reaction vessel to carry out a hydrothermal reaction, so as to load Fe3O4 onto the carbon felt, and obtain the Fe3O4 / carbon felt composite material.

[0076] In this embodiment, after the first mixture and the second mixture are thoroughly mixed in a hydrothermal reactor, the hydrothermal reactor is placed in a water oven for hydrothermal reaction. The hydrothermal reaction temperature is 120°C, and the hydrothermal reaction time is 12 hours. The black precipitate in the hydrothermal reaction product is Fe3O4, and the extracted carbon felt is a carbon fiber composite felt loaded with Fe3O4, that is, a Fe3O4 / carbon felt composite material.

[0077] In some embodiments, the anode and cathode reaction electrodes are carbon fiber composite electrode felts. The carbon fiber composite electrode felt comprises, sequentially arranged, a first carbon fiber prepreg layer, a polytetrafluoroethylene (PTFE) film layer, a Fe3O4 / carbon felt composite material layer, and a second carbon fiber prepreg layer. The first and second carbon fiber prepreg layers are prepared by a hot-molding process, which includes curing at 0°C for 0.5-1 hour, followed by curing at 130°C for 15 hours at a curing pressure of 0.6 MPa. The carbon fiber composite electrode felt is prepared as follows: multiple layers of carbon fiber prepreg are stacked together, and a 25 μm thick PTFE film is inserted into the mid-plane between two adjacent layers of carbon fiber prepreg to induce pre-cracks. A Fe3O4 / carbon felt composite material is then inserted into the mid-plane adjacent to the PTFE film and the carbon fiber prepreg, thereby obtaining the carbon fiber composite electrode felt.

[0078] In the embodiments of this application, bioelectrocatalysis induces the enrichment of electroactive AnAOB and SRB into a film on the surface of the carbon fiber composite electrode felt, enhancing its function. This, combined with the effects of aeration shear force and the hydrophobicity of the carbon fiber layer, ensures a moderate content of microbial film in the electrode layer. The carbon fiber in the composite electrode felt possesses high toughness and corrosion resistance, protecting the Fe3O4 / carbon felt composite layer. This Fe3O4 / carbon felt composite layer exhibits high current transfer and strong bio-adhesion, enabling the formation of high power density.

[0079] The following describes the workflow of the wastewater treatment equipment provided in this application for treating coking wastewater, using coking wastewater as an example:

[0080] Step 1: The pretreated coking wastewater has a pH of 3-4 and a temperature of 25℃-30℃. The wastewater enters the first reaction chamber through the first inlet. The nitrogen generated by the first nitrogen generator is released through the first-stage aeration disc and the second-stage aeration disc in the first zone. After entering the first reaction chamber, the wastewater is mixed with the iron-based heterogeneous fluid catalyst contained in the first reaction chamber and undergoes a heterogeneous Fenton reaction.

[0081] Step 2: After the wastewater undergoes a preliminary reaction in the first zone reaction chamber, it passes through the first-stage aeration disc in the second zone and enters the second zone reaction chamber. Nitrogen generated by the first nitrogen generator is used to aerate the mixture in the second zone reaction chamber through the first-stage aeration disc and the second-stage aeration disc in the second zone, allowing the wastewater to undergo a deep reaction in the second zone reaction chamber.

[0082] Step 3: The wastewater containing the catalyst at the top of the second reaction chamber flows through the external return pipe and is pH-adjusted (e.g., adjusted to pH 3-4) by the return regulator before flowing back to the first reaction chamber.

[0083] Step 4: The wastewater that has completed the reaction in the second reaction chamber passes through a solid-liquid separation screen to separate the gas and liquid from the mixture. The separated gas and liquid reach the gas-liquid separation chamber. The gas entering the gas-liquid separation chamber is discharged through the first exhaust port, and the liquid is discharged through the first drain port. The liquid discharged from the first drain port is adjusted to pH 6 and temperature 30℃~35℃ by the water outlet regulator, and then enters the cathode chamber through the second water inlet.

[0084] Step 4: The iron sludge deposited in the Fenton reactor is discharged into the sludge equalization tank 40 through the first sludge discharge port for storage; the iron sludge in the sludge equalization tank is diverted to the anode reactor and the sludge discharge tank.

[0085] Step 5: After the coking wastewater discharged from the Fenton reaction tower enters the cathode chamber through the second inlet, the electrochemical workstation controls the cathode composite felt plate to carry out electrochemical action. The sulfur iron sludge deposited after the SRB reaction is discharged into the sludge discharge pool from the second sludge discharge port.

[0086] Step 6: Use the second nitrogen generator to generate nitrogen gas, and use it to strip the oxygen and hydrogen sulfide contained in the water in the cathode chamber through the cathode aeration plate. The gas in the cathode chamber is discharged from the second exhaust port.

[0087] Step 7: The wastewater after desulfurization and decarbonization in the cathode chamber is discharged into the anode chamber through the second drain outlet.

[0088] Step 8: Wastewater discharged from the second drain outlet enters the anode chamber through the third inlet. The electrochemical workstation controls the anode composite felt plate to carry out electrochemical action. Iron sludge output from the sludge equalization tank enters the anode chamber through the third sludge inlet, where iron-based anaerobic ammonium oxidation, nitrite-based anaerobic ammonium oxidation, and nitrate-dependent ferrous oxidation reactions take place.

[0089] Step 8: Use the third nitrogen generator to generate nitrogen gas, and use it to strip the oxygen in the water in the anode chamber through the anode aeration plate. The nitrogen and other gases generated by the biochemical reaction in the anode chamber are discharged from the third exhaust port.

[0090] Step 9: The cation exchange membrane automatically exchanges hydrogen ions, iron ions, and electrons in the water in the anode and cathode chambers; at the same time, the wastewater after the denitrification reaction in the anode chamber is discharged from the third outlet.

[0091] Wastewater treatment equipment has high reaction efficiency in treating coking wastewater, and the treated coking wastewater can meet the discharge standards.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wastewater treatment device, characterized in that, The device includes: A Fenton reaction tower, wherein the Fenton reaction tower is provided with a first drain outlet and a first sludge outlet; A cathode reactor, comprising a cathode reaction electrode, a cathode chamber, and a second inlet and a second outlet connected to the cathode chamber, wherein the second inlet is connected to the first outlet via a pipeline, and the cathode chamber contains sulfate-reducing bacteria. An anode reactor includes an anode electrode, an anode chamber, and a third water inlet, a third drain outlet, and a third sludge inlet connected to the anode chamber. The third water inlet is connected to the second drain outlet via a pipeline, and the third sludge inlet is connected to the first sludge discharge outlet via a pipeline. A cation exchange membrane is provided between the cathode chamber and the anode chamber, and the anode chamber is filled with iron-based anaerobic ammonia-oxidizing bacteria. During wastewater treatment, the anode reactor and the cathode reactor are in operation. The wastewater to be treated undergoes a Fenton reaction in the Fenton reactor for initial degradation, and is then discharged from the first drain outlet and enters the cathode chamber through the second inlet. The iron sludge generated during the Fenton reaction is discharged from the first sludge discharge outlet and fed into the anode chamber through the third sludge inlet. The wastewater in the cathode chamber undergoes a second degradation under the catalysis of sulfate-reducing bacteria, and is then discharged from the second drain outlet and enters the anode chamber through the third inlet. Under the catalysis of iron-based anaerobic ammonia-oxidizing bacteria, it undergoes a third degradation. The cations in the electrolyte in the anode chamber and the cathode chamber are exchanged through the cation exchange membrane.

2. The device according to claim 1, characterized in that, The anode and cathode reaction electrodes comprise Fe3O4 / carbon felt composite materials. The preparation method of the Fe3O4 / carbon felt composite material is as follows: The carbon felt was soaked in NaOH solution to obtain a first mixture, and the first mixture was subjected to ultrasonic treatment. FeSO4, Na2S2O3 and water were thoroughly mixed to obtain a second mixture; After the first mixture and the second mixture are thoroughly mixed, they are placed in a hydrothermal reaction vessel for hydrothermal reaction. The product of the hydrothermal reaction includes Fe3O4 / carbon felt composite material.

3. The device according to claim 2, characterized in that, The mass ratio of FeSO4 to Na2S2O3 ranges from (1:1) to (1.2:1).

4. The device according to claim 2, characterized in that, The ultrasonic treatment time is 20-30 minutes, the hydrothermal reaction temperature is 120°C, and the hydrothermal reaction time is 12 hours.

5. The device according to claim 2, characterized in that, The anode and cathode reaction electrodes comprise a first carbon fiber prepreg layer, a polytetrafluoroethylene film layer, the Fe3O4 / carbon felt composite material layer, and a second carbon fiber prepreg layer, arranged sequentially.

6. The device according to any one of claims 1-5, characterized in that, The anode reactor also includes an anode aeration disc, which is located near the bottom of the anode chamber and is used to aerate the water in the anode chamber with nitrogen. The cathode reactor also includes a cathode aeration disc, which is located near the bottom of the cathode chamber and is used to aerate the water in the cathode chamber with nitrogen.

7. The device according to claim 6, characterized in that, The Fenton reaction tower includes a first-zone aeration plate, a first-zone reaction chamber, a second-zone aeration plate, a second-zone reaction chamber, a solid-liquid separation net, and a gas-liquid separation chamber arranged sequentially from the bottom to the top of the Fenton reaction tower. The gas-liquid separation chamber is connected to the first drain outlet. The aeration disc in zone one and the aeration disc in zone two are respectively used to aerate the liquid-solid fluid in the reaction chamber in zone one and the reaction chamber in zone two with nitrogen gas. The solid-liquid separation mesh is used to allow liquids and gases to pass through while blocking solids.

8. The device according to claim 7, characterized in that, The Fenton reaction tower is also provided with a reflux outlet and a reflux inlet. The reflux inlet is connected to the first reaction chamber, and the reflux outlet is connected to the second reaction chamber. The reflux inlet and the reflux outlet are connected by a reflux pipe. The solid and liquid fluids in the second reaction chamber are returned to the first reaction chamber through the reflux pipe.

9. The device according to claim 8, characterized in that, The Fenton reaction tower also includes a reflux regulator, which is installed in the reflux pipe and is used to regulate the hydraulic flow rate and pH value of the solid-liquid fluid in the reflux pipe.

10. The device according to claim 9, characterized in that, The anode reactor further includes an anode reference electrode, and the cathode chamber further includes a cathode reference electrode; The wastewater treatment equipment also includes a nitrogen generator and a controller. The nitrogen generator is connected to the pipelines of the cathode aeration disc, the anode aeration disc, the first-zone aeration disc, and the second-zone aeration disc. The controller is communicatively connected to the anode reaction electrode, the anode reference electrode, the cathode reaction electrode, the cathode reference electrode, and the nitrogen generator; The controller is used to control the electrochemical reactions in the anode reactor and the cathode reactor by adjusting the potentials of the anode reaction electrode and the cathode reaction electrode, and to control the nitrogen aeration rate of the cathode aeration plate, the anode aeration plate, the first-zone aeration plate and the second-zone aeration plate respectively by the nitrogen generator.

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