Electro-fenton system based on modified carbon felt cathode and method of application thereof

Abstract

This invention discloses an electro-Fenton system based on a modified carbon felt cathode, comprising a reactor containing an anode and a modified carbon felt cathode, arranged parallel to each other at intervals. An aeration device is located at the bottom of the reactor, near the modified carbon felt cathode, and is connected to an aeration pump via a pipe. The system also includes a DC power supply, with its positive terminal electrically connected to the anode and its negative terminal electrically connected to the modified carbon felt cathode. This invention also discloses a method for applying the electro-Fenton system based on the modified carbon felt cathode. This invention solves the problems of high operating costs and increased salt load caused by the reliance on acidic pH adjustment in traditional electro-Fenton technology.

Description

Technical Field

[0001] This invention belongs to the field of wastewater and sludge treatment technology, specifically relating to an electro-Fenton system based on a modified carbon felt cathode, and also to an application method of the electro-Fenton system based on a modified carbon felt cathode. Background Technology

[0002] Electro-Fenton technology typically generates hydrogen peroxide on the cathode side through an oxygen reduction reaction, which then synergistically with catalytically active sites in the system to generate highly oxidizing reactive species such as hydroxyl radicals (·OH), thereby oxidizing and degrading recalcitrant organic pollutants. However, traditional electro-Fenton processes often rely on acidic conditions (commonly pH 2.5-3.0) to improve reaction efficiency. When applied in municipal wastewater treatment plants, additional acid or alkali must be added for pH adjustment, leading to increased operating costs and salt load, thus limiting engineering feasibility.

[0003] Meanwhile, real water samples from municipal wastewater treatment plants have multiple matrix characteristics, including high salinity, suspended solids, colloids, and complex dissolved organic matter. Furthermore, disinfection byproducts may be formed in the disinfection unit, posing a risk of genotoxicity. Existing studies mostly focus on simulated wastewater or single water quality conditions, lacking systematic validation on multiple water samples from the entire process of real wastewater treatment plants, as well as integrated solutions that synergize with sludge reduction. Summary of the Invention

[0004] The purpose of this invention is to provide an electro-Fenton system based on a modified carbon felt cathode, which solves the problems of high operating costs and increased salt load caused by the reliance on acidic pH adjustment in traditional electro-Fenton technology.

[0005] Another object of the present invention is to provide a method for applying an electro-Fenton system based on a modified carbon felt cathode.

[0006] The technical solution adopted in this invention is an electro-Fenton system based on a modified carbon felt cathode, including a reactor, in which an anode and a modified carbon felt cathode are provided, the anode and the modified carbon felt cathode being arranged in parallel with a gap; an aeration device is provided at the bottom of the reactor, the aeration device being located near the modified carbon felt cathode, and the aeration device is connected to an aeration pump through a pipe; the system also includes a DC power supply, the positive terminal of the DC power supply being electrically connected to the anode, and the negative terminal of the DC power supply being electrically connected to the modified carbon felt cathode. The invention is further characterized by: The aeration device is a nano-air aeration disc, and the electrode distance between the anode and the modified carbon felt cathode is 0.5-5cm.

[0007] The reactor has a single-chamber structure, with both the anode and the modified carbon felt cathode immersed inside the reactor.

[0008] Another technical solution adopted in this invention is a method for applying an electro-Fenton system based on a modified carbon felt cathode, comprising the following steps: Step 1: Introduce the medium to be treated into the reactor; Step 2: Start the aeration device and aeration pump to aerate the medium to be treated in the reactor; Step 3: Turn on the DC power supply and apply voltage to the anode and the modified carbon felt cathode; Step 4: After the set residence time has elapsed, discharge the medium from the reactor.

[0009] Another feature of the technical solution adopted in this invention is that: The medium to be treated is the influent from a municipal wastewater treatment plant or the effluent from an aeration tank, with an initial pH of 6.5-8.5; in step 2, aeration is performed to bring the dissolved oxygen concentration in the reactor to 2-8 mg / L; in step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm². 2 In step 4, the residence time is 10-60 min; the COD removal rate of the treated influent is 51.8% and the TOC removal rate is 67.2%, or the COD removal rate of the aeration tank effluent is 36.5% and the TOC removal rate is 73.2%. The medium to be treated is the final effluent after chlorine disinfection, with an initial pH of 6.5-8.5. In step 2, aeration is performed to bring the dissolved oxygen concentration in the reactor to 2-8 mg / L. In step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm². 2 In step 4, the residence time is 10-60 min; the total TELI of the treated effluent decreased from 2.32 to 1.50, and the DNA damage TELI_DNA decreased from 5.52 to 1.29.

[0010] The medium to be treated is the effluent from the secondary sedimentation tank or the final effluent. The initial pH of the medium is 6.5-8.5. In step 2, aeration is performed to bring the dissolved oxygen concentration in the reactor to 2-8 mg / L. In step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm². 2 In step 4, the residence time is 10-60 min; after treatment, the number of antibiotic resistance genes (ARGs) in the effluent decreased by 29% to 37%.

[0011] The medium to be treated was residual sludge from the secondary sedimentation tank, with an initial pH of 6.5-8.5. In step 2, aeration was performed to bring the dissolved oxygen concentration in the reactor to 2-6 mg / L. In step 3, the applied voltage was 1.0-3.0 V. In step 4, the retention time was 60-180 min. After treatment, the MLSS of the sludge decreased by 61.1%, the MLVSS decreased by 51.9%, and the SVI of the sludge increased, indicating that the floc structure changed from dense to loose and dispersed.

[0012] The beneficial effects of this invention are: The electro-Fenton system based on modified carbon felt cathode and its application method provided by this invention can operate stably under neutral pH conditions without acidification or alkalization of municipal sewage or sludge, significantly reducing pH adjustment costs and salt load. It achieves removal rates of 51.8% and 67.2% for influent chemical oxygen demand (COD) and total organic carbon (TOC), respectively, and 36.5% and 73.2% for aeration tank effluent, respectively, effectively reducing organic matter. It reduces total TELI in chlorinated effluent from 2.32 to 1.50 and DNA damage TELI_DNA from 5.52 to 1.29, significantly reducing the risk of genotoxicity related to disinfection byproducts. It also reduces the abundance of antibiotic resistance genes in the final effluent by 29%-37%. After treatment of residual sludge in the secondary sedimentation tank, it reduces MLSS by 61.1% and MLVSS by 51.9%, achieving significant sludge reduction. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the electro-Fenton system based on the modified carbon felt cathode of the present invention; Figure 2 This is a schematic diagram of the entire sampling process in Embodiment 3 of the present invention; Figure 3 This is a schematic diagram showing the changes in chemical oxygen demand (COD) before and after treatment of different unit water samples in Example 3 of the present invention. Figure 4 This is a schematic diagram illustrating the changes in total organic carbon before and after treatment of different unit water samples in Example 3 of the present invention; Figure 5 This is a schematic diagram showing the changes in biochemical oxygen demand (BOD) of different water samples before and after treatment over five days in Example 3 of the present invention. Figure 6 This is a schematic diagram illustrating the changes in the transcriptional effect level index (TELI) of different unit water samples before treatment in Example 4 of the present invention. Figure 7 This is a schematic diagram illustrating the changes in the transcriptional effect level index (TELI) after different unit water sample treatments in Example 4 of the present invention. Figure 8 This is a schematic diagram illustrating the relative abundance changes of mobile genetic elements before and after treatment of different unit water samples in Embodiment 5 of the present invention; Figure 9 This is a schematic diagram illustrating the changes in the relative abundance of drug resistance genes before and after treatment of different unit water samples in Example 5 of the present invention; Figure 10 This is a schematic diagram showing the changes in MLSS and MLVSS of the mixed liquor before and after the treatment of residual sludge in the secondary sedimentation tank in Example 6 of the present invention. Figure 11This is a schematic diagram showing the change in sludge index (SVI) before and after the treatment of residual sludge in the secondary sedimentation tank in Embodiment 6 of the present invention.

[0014] In the diagram, 1. Reactor, 2. Anode, 3. Modified carbon felt cathode, 4. Aeration device, 5. Aeration pump, 6. DC power supply, 7. Magnetic stirrer. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] The electro-Fenton system based on a modified carbon felt cathode provided by this invention, such as... Figure 1 As shown, the system includes a reactor 1, which contains an anode 2 and a modified carbon felt cathode 3, arranged parallel to each other at intervals. An aeration device 4 is located at the bottom of the reactor 1, near the modified carbon felt cathode 3, and is connected to an aeration pump 5 via a pipe. The system also includes a DC power supply 6, with its positive terminal connected to the anode 2 and its negative terminal connected to the modified carbon felt cathode 3. The aeration device 4 is a nano-air aeration disc, and the distance between the anode 2 and the modified carbon felt cathode 3 is 0.5-5 cm. The reactor 1 has a single-chamber structure, with both the anode 2 and the modified carbon felt cathode 3 immersed within it.

[0017] The present invention provides a method for applying an electric Fenton system based on a modified carbon felt cathode, comprising the following steps: Step 1: Introduce the medium to be treated into the reactor; Step 2: Start the aeration device and aeration pump to aerate the medium to be treated in the reactor; Step 3: Turn on the DC power supply and apply voltage to the anode and the modified carbon felt cathode; Step 4: After the set residence time has elapsed, discharge the medium from the reactor.

[0018] Cathode electro-Fenton (EF): Under the action of an external electric field, the cathode undergoes an oxygen reduction reaction to generate intermediates such as H2O2, and in synergy with the catalytic sites of the system, it produces highly oxidizing active species such as ·OH, thereby achieving the oxidative degradation and detoxification of organic pollutants.

[0019] Removal rate calculation: The organic matter removal rate η is calculated according to formula (1): η=(C0 C t ) / C0×100%, where C0 is the concentration before treatment, C t The concentration is t after treatment. When expressed as COD, TOC, or other indicators, C is taken as the corresponding measured value.

[0020] The transcriptional effect level index (TELI) is used to evaluate the intensity of a sample's toxic response induced by the tested model organism; TELIDNA is used to characterize the degree of DNA damage-related toxic response. In the embodiments of this invention, TELI and TELIDNA can be obtained according to the established procedures of the experimental platform or standardized bioassay methods.

[0021] SMP / EPS: SMP is a soluble microbial product; EPS is an extracellular polymeric substance, which can be further divided into loosely bound LB-EPS and tightly bound TB-EPS.

[0022] Example 1 The electro-Fenton system based on a modified carbon felt cathode proposed in this embodiment, such as... Figure 1 As shown, the system includes a reactor 1, which contains an anode 2 and a modified carbon felt cathode 3, arranged in parallel with the anode 2 at intervals. An aeration device 4 is installed at the bottom of the reactor 1, located near the modified carbon felt cathode 3, and the aeration device 4 is connected to an aeration pump 5 via a pipe. The system also includes a DC power supply 6, with the positive terminal of the DC power supply 6 electrically connected to the anode 2 and the negative terminal of the DC power supply 6 electrically connected to the modified carbon felt cathode 3.

[0023] Example 2 The electro-Fenton system based on a modified carbon felt cathode proposed in this embodiment, such as... Figure 1 As shown, the system includes a reactor 1, which contains an anode 2 and a modified carbon felt cathode 3, arranged parallel to each other at intervals. An aeration device 4 is located at the bottom of the reactor 1, near the modified carbon felt cathode 3, and is connected to an aeration pump 5 via a pipe. The system also includes a DC power supply 6, with its positive terminal connected to the anode 2 and its negative terminal connected to the modified carbon felt cathode 3. The aeration device 4 is a nano-air aeration disc, and the distance between the anode 2 and the modified carbon felt cathode 3 is 0.5-5 cm. The reactor 1 has a single-chamber structure, with both the anode 2 and the modified carbon felt cathode 3 immersed within it.

[0024] Example 3 The proposed method for applying an electro-Fenton system based on a modified carbon felt cathode in this embodiment is used for enhanced treatment of municipal wastewater samples from the entire process under neutral conditions. The electro-Fenton system based on the modified carbon felt cathode described above includes the following steps: (1) Sampling and numbering: such as Figure 2 As shown, water samples were collected from different units throughout the entire process of the same municipal wastewater treatment plant and numbered W1-W9.

[0025] Wastewater samples: including influent W1, aeration tank effluent W2, anaerobic tank water W3, anoxic tank 1 water W4, aerobic tank 1 water W5, anoxic tank 2 water W6, aerobic tank 2 water W7, secondary sedimentation tank effluent W8, and chlorine-disinfected final effluent W9. Sludge samples: including anaerobic tank sludge S1, anoxic tank 1 sludge S2, aerobic tank 1 sludge S3, anoxic tank 2 sludge S4, aerobic tank 2 sludge S5 and secondary sedimentation tank sludge S6, and sludge supernatant samples: anaerobic tank sludge supernatant SW1, anoxic tank 1 sludge supernatant SW2, aerobic tank 1 sludge supernatant SW3, anoxic tank 2 sludge supernatant SW4, aerobic tank 2 sludge supernatant SW5 and secondary sedimentation tank sludge supernatant SW6; Each sampling point corresponds to typical locations such as influent, before and after the biological treatment unit, before and after the secondary sedimentation tank, advanced treatment, and final effluent. After sampling, samples are stored at 4℃ in the dark and the treatment test is completed within 24 hours.

[0026] (2) Pretreatment: Measure the initial pH, DO, temperature, turbidity (or SS) and basic water quality indicators (COD, TOC, etc.) of each water sample. To ensure comparability, each sample should be thoroughly mixed before treatment; if the water sample contains large particles, it can be coarsely filtered first (e.g., 100-300 μm sieve) to avoid clogging the aeration head, but without changing the dissolved components.

[0027] (3) Operating conditions: Add water sample to the reactor, maintain the pH of the raw water (neutral range), start aeration and apply external voltage. It is preferred to operate at room temperature (20-30℃); a magnetic stirrer or a circulating pump can be used for stirring to ensure uniform mixing.

[0028] (4) Sampling and Analysis: Samples were taken at time points t=0, 5, 10, 20, 30, 60, and 120 min. COD was determined by the dichromate method or an equivalent standard method, such as... Figure 3 As shown; TOC was measured using a TOC analyzer, such as... Figure 4 As shown; biochemical properties can be determined by measuring BOD5 or BOD5 / COD, such as... Figure 5 As shown; the structure of soluble organic matter can be characterized by three-dimensional fluorescence (EEM) to identify changes in peak regions such as protein-like / humic substances.

[0029] (5) Results: EF significantly reduced organic matter in both the influent and the effluent from the aeration tank. The COD and TOC removal rates for influent W1 were 51.8% and 67.2%, respectively, while those for effluent W2 from the aeration tank were 36.5% and 73.2%, respectively. For the end-of-pipe water sample, the removal rate was relatively lower due to the lower concentration of oxidizable organic matter, but it can still be used as a deep oxidation / detoxification unit.

[0030] (6) Process layout recommendations: When the goal is to reduce biochemical load and improve biodegradability, it is preferable to set the EF unit of the present invention at the front end of the biochemical reactor or at a key intermediate node; when the goal is to reduce toxicity after disinfection, it is preferable to set it at the end after chlorine disinfection.

[0031] Example 4 The proposed method for applying an electro-Fenton system based on a modified carbon felt cathode in this embodiment is used for the reduction of toxicity and control of genotoxicity risks in chlorinated effluent. The electro-Fenton system based on the modified carbon felt cathode described above includes the following steps: (1) Subject: The final effluent after chlorine disinfection was selected as the subject to be treated (W9). This type of water sample may have the risk of forming disinfection byproducts and exhibits high overall toxicity and DNA damage-related toxicity response.

[0032] (2) Operating procedures: Perform EF treatment under neutral pH conditions according to the general procedure in 5.2. To balance toxicity reduction and energy consumption, a shorter residence time (10-60 min) is preferred, and the reaction intensity is controlled by online current monitoring; if necessary, bypass circulation can be used to ensure contact efficiency.

[0033] (3) Toxicity evaluation: TELI and TELI DNA were measured before and after treatment, respectively. Figure 6 , 7 As shown. To ensure the reliability of the results, it is preferable to set up negative / positive controls and conduct at least three parallel experiments (n≥3), and take the mean and standard deviation.

[0034] (4) Results: The total TELI in the chlorine-disinfected effluent was 2.32, which decreased to 1.50 after EF treatment; the DNA damage TELI DNA decreased significantly from 5.52 to 1.29, indicating that the potential genotoxicity was significantly alleviated.

[0035] (5) Engineering application: The unit of the present invention can be connected in series after the disinfection contact tank or on the effluent pipeline as a terminal risk control barrier; it can also be connected in parallel or in series with deep treatment such as activated carbon and membrane method to achieve a higher safety margin.

[0036] Example 5 The proposed method for using an electro-Fenton system based on a modified carbon felt cathode in this embodiment is for reducing the risk of antibiotic resistance genes (ARGs) in the final effluent. The electro-Fenton system based on the modified carbon felt cathode described above includes the following steps: (1) Subjects: Select terminal related samples (W8, W9) for EF treatment, and retain the untreated samples as controls.

[0037] (2) Enrichment and DNA extraction: Water samples were filtered to enrich microorganisms (using a 0.22 μm filter membrane) at equal volumes, and total DNA was extracted using a commercially available kit or equivalent method. It is preferable to include a blank filter membrane control and perform DNA purification to reduce the influence of inhibitors.

[0038] (3) ARGs analysis: metagenomic sequencing can be used to count the types and quantities of ARGs; or qPCR can be used to quantify typical ARGs. The statistical standards should remain consistent before and after treatment.

[0039] (4) Results: After EF treatment, the number of ARGs in W8 and W9 decreased by approximately 29% and 37%, respectively. Figure 8 , 9 As shown in the figure. This result indicates that the present invention can reduce the abundance of resistance genes in the terminal effluent, thereby reducing the risk of transmission.

[0040] (5) Quality control: It is preferable to record the filter volume, DNA concentration / purity, sequencing depth (or qPCR efficiency), and use internal references or standard curves for calibration to ensure comparability.

[0041] Example 6 The proposed method for applying an electro-Fenton system based on a modified carbon felt cathode in this embodiment is used for reducing excess sludge in a secondary sedimentation tank. The electro-Fenton system based on the modified carbon felt cathode described above includes the following steps: (1) Subject: Take the residual sludge (S6) from the secondary sedimentation tank as the treatment subject and record the initial MLSS, MLVSS, SVI and pH.

[0042] (2) Operating conditions: Add sludge to the reactor, maintain the pH of the raw sludge (neutral range), start aeration and apply a low external voltage. The purpose of low-pressure operation is to induce the release of SMP / EPS and the reconstruction of floc structure with low energy consumption, so as to achieve volume reduction rather than simple mechanical crushing.

[0043] (3) Monitoring indicators and methods: MLSS / MLVSS were determined according to the standard method (drying at 105 ℃ and burning at 550 ℃); SVI was determined according to the standard sedimentation volume index method; microscopy / particle size analyzer can be used to characterize floc dispersion; SMP, LB-EPS, and TB-EPS can be extracted by heating, centrifugation, ion exchange resin or equivalent methods, and TOC and EEM fluorescence characteristics were measured.

[0044] (4) Results: After EF treatment, the MLSS and MLVSS of the sludge decreased by 61.1% and 51.9%, respectively. Figure 10 As shown; after approximately 180 minutes of treatment, the SVI increased, indicating that the floc structure changed from dense to loose and dispersed, as... Figure 11As shown in the figure. Combining the changes in TOC and fluorescence characteristics of SMP / EPS, we can characterize the leakage of intracellular soluble components and the cleavage of EPS macromolecules into the aqueous phase, thereby promoting sludge reduction.

[0045] (5) Subsequent disposal (optional): The sludge after EF treatment can be sent to the existing thickening / dewatering system; the supernatant can be returned to the front end of the plant or sent to the advanced treatment unit. In engineering, the impact on the main process can be avoided by optimizing the reflux ratio and residence time.

[0046] To further demonstrate the engineering feasibility of this invention, parameter window optimization and continuous operation examples can be performed: (1) Voltage / current window: In regulated mode, set gradients of 1.0, 2.0, 3.0, and 5.0 V; or in constant current mode, set gradients of 1, 3, 5, and 10 mA / cm2. Compare the COD / TOC removal, TELI reduction, and energy consumption, and select the optimal window for "removal / detoxification benefits per unit of energy consumption".

[0047] (2) Aeration intensity: Set different aeration rates (e.g., 0.1, 0.3, 0.5, 1.0 mL / min) or different DO target ranges (2, 4, 6 mg / L), compare the treatment effects and determine the minimum effective aeration intensity.

[0048] (3) Hydraulic retention time: Set 10, 20, 30, 60, 120, 180 min, etc., plot the curve of removal / detoxification with retention time, and determine the shortest retention time that meets the standards and is economical.

[0049] (4) Continuous operation: Under the selected parameters, operate in a continuous inlet and outlet mode for 7-30 days, and record changes in current, pH, DO, effluent COD / TOC and TELI; periodically flush or backflush the cathode to reduce fouling, and evaluate the electrode performance degradation.

Claims

1. An electro-Fenton system based on a modified carbon felt cathode, characterized in that, The system includes a reactor (1), which contains an anode (2) and a modified carbon felt cathode (3). The anode (2) and the modified carbon felt cathode (3) are arranged parallel to each other at intervals. An aeration device (4) is provided at the bottom of the reactor (1). The aeration device (4) is located near the modified carbon felt cathode (3). The aeration device (4) is connected to an aeration pump (5) through a pipe. The system also includes a DC power supply (6). The positive terminal of the DC power supply (6) is electrically connected to the anode (2), and the negative terminal of the DC power supply (6) is electrically connected to the modified carbon felt cathode (3).

2. The electro-Fenton system based on a modified carbon felt cathode according to claim 1, characterized in that, The aeration device (4) is a nano-air aeration disc, and the distance between the anode (2) and the modified carbon felt cathode (3) is 0.5-5cm.

3. The electro-Fenton system based on a modified carbon felt cathode according to claim 1, characterized in that, The reactor (1) is a single-chamber structure, and the anode (2) and the modified carbon felt cathode (3) are both immersed in the reactor (1).

4. A method for applying an electro-Fenton system based on a modified carbon felt cathode, characterized in that, The electro-Fenton system based on a modified carbon felt cathode according to any one of claims 1-3 includes the following steps: Step 1: Introduce the medium to be treated into reactor (1); Step 2: Start the aeration device (4) and aeration pump (5) to aerate the medium to be treated in the reactor (1); Step 3: Turn on the DC power supply (6) and apply voltage to the anode (2) and the modified carbon felt cathode (3); Step 4: After the set residence time is over, discharge the medium from reactor (1).

5. The application method of the electro-Fenton system based on the modified carbon felt cathode according to claim 4, characterized in that, The to-be-treated medium is influent or effluent of an aeration tank of a municipal sewage treatment plant, and the initial pH of the to-be-treated medium is 6.5-8.5; in the step 2, the dissolved oxygen concentration in the reactor (1) is 2-8 mg / L under aeration; in the step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm 2 ; in the step 4, the residence time is 10-60 min; after treatment, the COD removal rate in the influent is 51.8%, and the TOC removal rate is 67.2%, or the COD removal rate in the effluent of the aeration tank is 36.5%, and the TOC removal rate is 73.2%.

6. The application method of the electro-Fenton system based on the modified carbon felt cathode according to claim 4, characterized in that, The medium to be treated is the final effluent after chlorine disinfection, and the initial pH of the medium to be treated is 6.5-8.

5. In step 2, aeration is performed to bring the dissolved oxygen concentration in reactor (1) to 2-8 mg / L. In step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm². 2 In step 4, the residence time is 10-60 min; the total TELI of the treated effluent decreased from 2.32 to 1.50, and the DNA damage TELI_DNA decreased from 5.52 to 1.

29.

7. The application method of the electro-Fenton system based on the modified carbon felt cathode according to claim 4, characterized in that, The medium to be treated is the effluent from the secondary sedimentation tank or the final effluent. The initial pH of the medium to be treated is 6.5-8.

5. In step 2, aeration is performed to bring the dissolved oxygen concentration in reactor (1) to 2-8 mg / L. In step 3, the applied voltage is 1.0-10.0 V or the current density is 0.5-30 mA / cm². 2 In step 4, the residence time is 10-60 min; after treatment, the number of antibiotic resistance genes (ARGs) in the effluent decreases by 29% to 37%.

8. The application method of the electro-Fenton system based on the modified carbon felt cathode according to claim 4, characterized in that, The medium to be treated is residual sludge from the secondary sedimentation tank. The initial pH of the medium to be treated is 6.5-8.

5. In step 2, aeration is performed to make the dissolved oxygen concentration in reactor (1) 2-6 mg / L. In step 3, the applied voltage is 1.0-3.0 V. In step 4, the retention time is 60-180 min. After treatment, the MLSS of the sludge decreases by 61.1%, the MLVSS decreases by 51.9%, and the SVI of the sludge increases, indicating that the floc structure changes from dense to loose and dispersed.

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