A method for rapidly degrading thiamethoxam contaminated domestic sewage by using microalgae fuel cell

Abstract

This invention discloses a method for rapidly degrading thiamethoxam-contaminated domestic wastewater using a microalgae fuel cell. It relates to the fields of wastewater treatment, biodegradation of novel pollutants, microalgae resource utilization, and microbial fuel cell technology. The method constructs a dual-chamber microalgae fuel cell comprising an anaerobic power generation system at the anode and a Scenedessica photosynthetic system at the cathode. Under illumination, the external circuit remains closed, allowing electrons generated at the anode to be transferred to the cathode via the external circuit, and protons to migrate to the cathode chamber via a proton exchange membrane. Simultaneously, Scenedessica photosynthetically produces oxygen at the cathode, acting as an electron acceptor to complete the oxygen reduction reaction. In this coupled system, Scenedessica utilizes nutrients such as nitrogen and phosphorus in the wastewater for growth, metabolism, and conversion of thiamethoxam. This accelerates the bioconversion efficiency of thiamethoxam under the drive of the closed external circuit, simultaneously achieving a synergistic treatment effect of nitrogen and phosphorus removal, microalgae biomass accumulation, and continuous bioelectricity output.

Description

Technical Field

[0001] This invention belongs to the fields of wastewater treatment, biodegradation of novel pollutants, microalgae resource utilization, and microbial fuel cells, and particularly relates to a method for rapidly degrading thiamethoxam-polluted domestic wastewater using a microalgae fuel cell. Background Technology

[0002] Thiamethoxam, a typical neonicotinoid insecticide, is highly water-soluble and has strong environmental mobility. After application in farmland, it easily enters surface and groundwater environments through various pathways, including agricultural runoff, surface runoff, and contamination by domestic sewage. Existing research indicates that thiamethoxam and some of its degradation products may pose potential ecological risks to aquatic organisms and non-target organisms. Therefore, how to achieve rapid, low-carbon, and safe treatment of thiamethoxam-containing wastewater has become an urgent problem to be solved in the field of water treatment technology.

[0003] Currently, conventional wastewater treatment processes are mainly designed for conventional indicators such as chemical oxygen demand (COD), ammonia nitrogen, total nitrogen, and total phosphorus. For trace emerging organic pollutants like thiamethoxam, existing treatment processes typically lack dedicated targeted removal stages. This results in thiamethoxam and some of its degradation products remaining in the effluent even when conventional pollutant indicators meet discharge standards, making it difficult to effectively control its ecological risks.

[0004] To address the aforementioned issues, existing technologies employ advanced oxidation methods, photocatalysis, or electrochemical oxidation to improve the degradation efficiency of thiamethoxam. However, these physicochemical methods typically require large amounts of oxidants, catalysts, ultraviolet light sources, or continuous electrical energy input, resulting in high operating costs and potential limitations due to water quality fluctuations in practical applications. Furthermore, some studies have indicated that thiamethoxam may generate intermediate products with higher toxicity than the parent compound during its oxidative degradation process. Without subsequent biotransformation or systematic toxicity assessments, this could still pose secondary ecological risks.

[0005] In recent years, microalgae-based wastewater treatment technologies have attracted widespread attention due to their green, low-carbon nature and potential for resource recovery. Existing literature reports that some microalgae species (such as *Scenedesmus*) have a certain removal capacity for thiamethoxam. For example, some studies have indicated that under specific concentrations of thiamethoxam stress, certain *Scenedesmus* systems can achieve complete removal within approximately 12 days. However, the treatment cycle of this purely microalgae-based method remains relatively long, and its main objectives are limited to pollutant removal and microalgae biomass accumulation, without fully exploring its potential for energy recovery or accelerating degradation through enhanced electron transfer.

[0006] In addition, existing technologies have developed algae-bacteria symbiotic systems for the removal of nutrients and the degradation of some organic matter in domestic sewage. However, these systems typically do not involve the construction of closed external circuits and cannot recover chemical energy other than biomass energy; their degradation process mainly relies on biotransformation and physical adsorption, lacking the driving force of external electron transfer, resulting in the pollutant degradation rate and the system's resource utilization level still needing improvement.

[0007] Microalgae fuel cells, as an emerging bioelectrochemical technology, theoretically couple the organic matter oxidation process of anolyl electroactive bacteria with the photosynthetic oxygen supply process of cathode microalgae, thereby achieving synergistic effects of pollutant removal and bioelectricity output. However, current research on microalgae fuel cells largely focuses on the removal efficiency and power generation performance of conventional pollutants (such as COD and nitrogen and phosphorus). Systematic technical solutions and in-depth research are still lacking regarding the treatment of neonicotinoid pesticide wastewater such as thiamethoxam, especially how to utilize this system to achieve rapid degradation of these pollutants and control the toxicity of degradation products.

[0008] In summary, existing technologies for treating thiamethoxam-containing domestic wastewater generally suffer from problems such as long degradation cycles, inability to simultaneously achieve energy recovery, high costs and risks associated with physicochemical methods, and low electron transfer efficiency in biological methods. Therefore, there is an urgent need in this field to develop a comprehensive treatment solution that can effectively shorten the degradation cycle of thiamethoxam and simultaneously achieve the reduction of conventional pollutants and the utilization of biomass resources. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a method for rapidly degrading thiamethoxam-polluted domestic sewage using a microalgae fuel cell. This method involves constructing an anaerobic electroactive bacterial community at the anode and a Scenedesmus sp. TXH photosynthetic system at the cathode within a dual-chamber microalgae fuel cell. The cathode Scenedesmus grows using sewage nutrients and provides oxygen under light conditions, while the anaerobic system at the anode oxidizes organic matter and outputs electrons. This achieves rapid degradation of thiamethoxam, simultaneous removal of nitrogen and phosphorus from domestic sewage, accumulation of microalgae biomass and photosynthetic pigments, and bioelectricity output.

[0010] This invention provides a method for rapidly degrading thiamethoxam-contaminated domestic sewage using microalgae fuel cells, comprising: A dual-chamber microalgae fuel cell is provided, the dual-chamber microalgae fuel cell including an anode chamber, a cathode chamber, a proton exchange membrane disposed between the anode chamber and the cathode chamber, an anode electrode disposed in the anode chamber, a cathode electrode disposed in the cathode chamber, and an external circuit connecting the anode electrode and the cathode electrode; Anaerobic electrogenic microorganisms were inoculated into the anode chamber to construct an anode anaerobic system; Domestic sewage containing thiamethoxam was introduced into the cathode chamber, and Scenedesmus was inoculated into the cathode chamber to construct a cathode photosynthetic microalgae system; The cathode chamber is subjected to photochemical culturing, and the external circuit is kept closed during the photochemical culturing process. This allows the anaerobic system at the anode to oxidize organic matter and generate electrons and protons. The electrons are transferred to the cathode electrode via the external circuit, and the protons migrate to the cathode chamber via the proton exchange membrane. The Scenedessella in the cathode chamber produces oxygen through photosynthesis, which acts as an electron acceptor. An oxygen reduction reaction occurs on the surface of the cathode electrode. At the same time, the Scenedessella utilizes nutrients in the domestic sewage for growth, metabolism, and conversion of the thiamethoxam, thereby achieving the treatment of thiamethoxam-containing wastewater and bioelectricity output.

[0011] Optionally, in the step of providing a dual-chamber microalgae fuel cell, the dual-chamber microalgae fuel cell adopts a dual-chamber reactor, the anode chamber and the cathode chamber are separated by the proton exchange membrane, the anode electrode and the cathode electrode are both carbon paper electrodes, the external circuit connects the anode electrode and the cathode electrode through titanium wire, and the external circuit is connected in series with an external resistor and connected to a voltage recording device.

[0012] Optionally, in the step of inoculating the anode chamber with anaerobic electrogenic microorganisms, the anaerobic electrogenic microorganisms are derived from anaerobic wastewater from the wastewater treatment plant and sludge from the sludge pumping station.

[0013] Optionally, in the step of introducing domestic sewage containing thiamethoxam into the cathode chamber, the initial concentration of thiamethoxam in the domestic sewage is between 1 mg / L and 10 mg / L.

[0014] Optionally, in the step of inoculating the cathode chamber with Scenedesmus sp. TXH strain, the inoculation amount of Scenedesmus is 0.1 g per liter based on cell dry weight.

[0015] Optionally, in the step of inoculating the cathode chamber with Scenedesmus, no additional inorganic nutrients are added to the cathode chamber, and the Scenedesmus utilizes the nitrogen, phosphorus and organic matter in the domestic sewage as a source of nutrients for growth.

[0016] Optionally, in the step of photo-culturing the cathode chamber, the culture temperature is 25 degrees Celsius, the light intensity is 40 micromoles per square meter per second, continuous photo-culturing is adopted, and the operation cycle is 6 days.

[0017] Optionally, the resistance of the external resistor connected in series in the external circuit is 1000 ohms.

[0018] Optionally, the carbon paper electrode has a size of 3 cm × 3 cm.

[0019] Optionally, the internal dimensions of each chamber of the dual-chamber microalgae fuel cell are 6 cm × 7 cm × 6 cm, and the working volume is 245 ml.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects: This invention constructs a dual-chamber microalgae fuel cell system, coupling the organic substrate oxidation process of anaerobic electrogenic microorganisms in the anode chamber with the photosynthesis of Scenedesmus in the cathode chamber, forming a stable electron transport pathway under a closed external circuit. Electrons released by the anode microorganisms oxidizing organic matter are directionally transferred to the cathode via the external circuit, while protons migrate synchronously to the cathode chamber through the proton exchange membrane. Under illumination, the cathode scenedesmus utilizes nutrients such as nitrogen and phosphorus in the wastewater to perform photosynthesis and produce dissolved oxygen. This photosynthetically produced oxygen continuously participates in the oxygen reduction reaction as an electron acceptor on the cathode surface, thereby constructing a complete bioelectrochemical cycle.

[0021] In this coupled system, the Scenedesmus in the cathode chamber not only maintains the continuous cathodic reaction through photosynthetic oxygen supply, but its own growth and metabolic activities also simultaneously biotransform thiamethoxam in the wastewater, thus achieving synergistic operation of pollutant removal and bioelectric output. The presence of a closed external circuit accelerates the electron transfer rate within the system, and the aerobic microenvironment formed in the cathode region due to photosynthetic oxygen production enhances the metabolic activity of Scenedesmus and promotes its uptake and transformation efficiency of thiamethoxam, significantly shortening the degradation cycle of thiamethoxam compared to a simple microalgae system.

[0022] Meanwhile, during its growth, Scenedesmus absorbs large amounts of nitrogen and phosphorus nutrients from wastewater, achieving simultaneous removal of conventional pollutants. The continuous accumulation of microalgal biomass further lays the foundation for subsequent biomass resource utilization. In addition, the system does not require external aeration for oxygen supply during operation, relying solely on photosynthesis to meet the cathode oxygen demand, resulting in low overall energy consumption and good economic viability and application prospects. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the method flow according to an embodiment of the present invention. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0026] Example 1 like Figure 1 As shown, this embodiment provides a method for rapidly degrading thiamethoxam-contaminated domestic sewage using a microalgae fuel cell, comprising: A dual-chamber microalgae fuel cell is provided, the dual-chamber microalgae fuel cell including an anode chamber, a cathode chamber, a proton exchange membrane disposed between the anode chamber and the cathode chamber, an anode electrode disposed in the anode chamber, a cathode electrode disposed in the cathode chamber, and an external circuit connecting the anode electrode and the cathode electrode; Anaerobic electrogenic microorganisms were inoculated into the anode chamber to construct an anode anaerobic system; Domestic sewage containing thiamethoxam was introduced into the cathode chamber, and Scenedesmus was inoculated into the cathode chamber to construct a cathode photosynthetic microalgae system; The cathode chamber is subjected to photochemical culturing, and the external circuit is kept closed during the photochemical culturing process. This allows the anaerobic system at the anode to oxidize organic matter and generate electrons and protons. The electrons are transferred to the cathode electrode via the external circuit, and the protons migrate to the cathode chamber via the proton exchange membrane. The Scenedessella in the cathode chamber produces oxygen through photosynthesis, which acts as an electron acceptor. An oxygen reduction reaction occurs on the surface of the cathode electrode. At the same time, the Scenedessella utilizes nutrients in the domestic sewage for growth, metabolism, and conversion of the thiamethoxam, thereby achieving the treatment of thiamethoxam-containing wastewater and bioelectricity output.

[0027] As a feasible implementation method, the specific steps include: (1) Assembly of microalgae fuel cell (AMFC) device: A dual-chamber microalgae fuel cell is used as the reaction device. The reactor material is polyethylene. The internal dimensions of a single chamber are 6cm×7cm×6cm (W×L×H), the total volume is 250mL, and the working volume is 245mL. The two chambers are connected by a proton exchange membrane, which is Nafion N117. Carbon paper is used as the electrode for both the cathode and the anode. The electrode size is 3cm×3cm. The cathode electrode and the anode electrode are connected to the external circuit through titanium wire. The external circuit is connected in series with a 1000Ω external resistor and a paperless voltage recorder is connected to record the output voltage. (2) Anode system construction: Wastewater from the anaerobic pool of the wastewater treatment plant and sludge from the sludge pumping station are inoculated into the anode chamber to form an anaerobic microbial and electroactive bacterial community system in the anode chamber; In a specific embodiment, the anode inoculum comes from wastewater from the anaerobic pool of the Dongxihu wastewater treatment plant and sludge from the sludge pumping station. (3) Construction of cathode reaction solution: Add domestic sewage from the inlet of the sewage treatment plant to the cathode chamber, and add thiamethoxam to make the initial concentration of thiamethoxam in the cathode chamber 0, 1, 5 or 10 mg / L; where 0 mg / L is the blank control, and 1 to 10 mg / L is the range of domestic sewage treatment with low concentration of thiamethoxam pollution. (4) Inoculation of Scenedesmus: Inoculate the cathode chamber described in step (3) with Scenedesmus. Scenedesmus sp. TXH, inoculated at a rate of 0.1 g / L based on cell dry weight; no additional inorganic nutrients are added to the cathode chamber, utilizing the nitrogen, phosphorus, and organic matter already present in the influent sewage as nutrients. Scenedesmus Nutritional sources required for the growth of sp. TXH; (5) Illuminated culture and power generation operation: The AMFC device constructed in steps (1) to (4) was placed under illumination and operated. The culture environment temperature was 25℃ and the light intensity was controlled at 40µmol / (m²). 2 •s), using 24h continuous light incubation; during operation, the external circuit is kept closed, and an electric power generation circuit is formed through a 1000Ω external resistor, and the voltage is continuously recorded by a paperless voltage recorder; the operation cycle is 6 days; (6) Pollutant degradation and simultaneous removal of nitrogen and phosphorus: During the operation of step (5), the cathode Scenedesmus sp.TXH performs biotransformation of thiamethoxam and its degradation products, while absorbing nitrogen and phosphorus nutrients from domestic sewage; the anaerobic bacteria at the anode oxidize organic substrates to generate electrons, which are transferred to the cathode through an external circuit, and protons migrate to the cathode through a proton exchange membrane. Under the photosynthetic oxygen supply conditions at the cathode, the oxygen reduction reaction is completed, thereby achieving rapid degradation of thiamethoxam, removal of nitrogen and phosphorus, accumulation of microalgal biomass, and bioelectricity output. (7) Control system setup: An algae-bacteria group was set up as a comparison system. The cathode inoculum, initial concentration of thiamethoxam and inoculum amount of Scenedesmus sp. TXH in the algae-bacteria group were kept consistent with the AMFC cathode system, but no closed external circuit structure of anode-proton exchange membrane-cathode was set up. This was used to compare the promoting effect of AMFC electrochemical coupling on thiamethoxam degradation, microalgae growth, nitrogen and phosphorus removal and bioelectric output.

[0028] In step (1), a polyethylene dual-chamber reactor is preferably used, with the two chambers connected by a Nafion N117 proton exchange membrane; both the cathode and anode electrodes are 3 cm × 3 cm carbon paper, the external circuit is connected by titanium wire, and a 1000 Ω external resistor and voltage recording device are connected in series.

[0029] In step (2), the anode chamber is preferably inoculated with sewage from the anaerobic pool of a wastewater treatment plant and sludge from the sludge pumping station to provide anaerobic electrogenic microorganisms, denitrification-related microorganisms and organic substrate degradation microorganisms. When making a formal application, the source of inoculation can be summarized as sewage from the anaerobic pool of a wastewater treatment plant and residual sludge or sludge from the sludge pumping station to avoid the claims being limited by specific place names.

[0030] In step (3), the cathode chamber preferably uses domestic sewage from the inlet of a sewage treatment plant as the reaction liquid, and the initial concentration of thiamethoxam is preferably 1 to 10 mg / L; in specific embodiments, four concentration groups of 0, 1, 5 and 10 mg / L are set.

[0031] In step (4), the preferred inoculum amount of Scenedesmus sp. TXH is 0.1 g / L (based on cell dry weight), which enables rapid colonization and dominant growth in the cathode environment of domestic sewage.

[0032] In step (5), the preferred culture conditions are 25±1℃ and 40µmol / (m 2 •s) Continuous light, 24h light incubation and 6d operation cycle; under these conditions, 1, 5 and 10 mg / L thiamethoxam can be degraded within 48h in the AMFC system, while in the ordinary algae group (non-AMFC system), 1 and 5 mg / L thiamethoxam are degraded in about 54h, and 10 mg / L thiamethoxam is degraded in about 60h.

[0033] In step (6), the AMFC system can simultaneously achieve the removal of conventional pollutants and the accumulation of bioelectricity within a 6-day operating cycle; the TDP removal rate of the 0 and 1 mg / L groups can reach 99.99%, the NH4+-N removal rate of the 1 mg / L group can reach 84.39%, and the TDN removal rate of the AMFC control group can reach 58.89%; the highest output voltages of the 0, 1, 5, and 10 mg / L groups can reach 393, 366, 342, and 372 mV, respectively, and the highest power densities can reach 1.14, 0.95, 0.78, and 0.62 mW / m, respectively. 2 .

[0034] In a preferred embodiment, the highest cell dry weight of *Scenedesmus sp. TXH* in the AMFC system was 2.81 g / L in the 1 mg / L thiamethoxam group; the highest cell dry weight in the common algae group was 2.26 g / L. In the AMFC cathode... Scenedesmus sp. TXH can become the dominant organism within 6 days, with the relative abundance of Chlorophyta increasing from 0.69% on day 0 to 99.88% on day 6, and the relative abundance of Scenedesmus increasing from 0.004% on day 0 to 99.86% on day 6.

[0035] Compared with the prior art, the present invention has the following positive technical effects: (1) Significantly shortens the thiamethoxam removal cycle. In previous studies on simple microalgae treatment, it usually takes about 12 days to achieve complete removal of 5–40 mg / L thiamethoxam; in the AMFC system of this invention, 1, 5, and 10 mg / L thiamethoxam can all be degraded within 48 hours, significantly shortening the treatment cycle. Compared with the ordinary algae and bacteria group, the AMFC group also degrades thiamethoxam faster; in the algae and bacteria group, the 1 and 5 mg / L groups require about 54 hours to remove, and the 10 mg / L group requires about 60 hours to remove.

[0036] (2) Coupling of pollutant degradation and bioelectric output. AMFC generates output voltage during operation. The highest output voltages for the 0, 1, 5, and 10 mg / L groups are approximately 393, 366, 342, and 372 mV, respectively, with 6-day average output voltages of approximately 292.94, 287.25, 283.33, and 272.29 mV, respectively; the highest power densities are approximately 1.14, 0.95, 0.78, and 0.62 mW / m³, respectively. 2 This result demonstrates that the present invention is not simply a pollutant removal process, but rather achieves a synergistic effect of thiamethoxam degradation and bioelectric accumulation.

[0037] (3) Promotes microalgae growth and accumulation of value-added products. In the AMFC system Scenedesmus The overall biomass of sp. TXH was higher than that of the ordinary algae-bacteria system. The highest cell dry weight in the AMFC 1 mg / L group was approximately 2.81 g / L, while the highest cell dry weight in the algae-bacteria group was approximately 2.26 g / L. The AMFC system has higher microalgal biomass and photosynthetic pigment content, which can provide a basis for the subsequent recovery of value-added products such as photosynthetic pigments, EPS, soluble proteins, and algal biomass.

[0038] (4) Simultaneous removal of nitrogen and phosphorus from domestic sewage. The AMFC system can remove conventional pollutants such as TDP, NH4+-N and TDN within 6 days. The TDP removal rate in the 0 and 1 mg / L groups can reach 99.99%, the NH4+-N removal rate in the 1 mg / L group can reach 84.39%, and the TDN removal rate in the AMFC control group can reach 58.89%. This system can reduce nutrients in domestic sewage while treating thiamethoxam.

[0039] (5) The cathode functional algae can rapidly colonize and become the dominant organisms. After the initial inoculation of the AMFC cathode, Scenedesmus sp. TXH rapidly became the dominant species within 6 days, with the relative abundance of Chlorophyta increasing from 0.69% on day 0 to 99.88% on day 6, and the relative abundance of Scenedesmus increasing from 0.004% on day 0 to 99.86% on day 6. This indicates that... Scenedesmus sp.TXH exhibits good adaptability to cathode environments and competitiveness.

[0040] (6) It has the potential for low-carbon resource utilization. The system uses domestic sewage as a nutrient source and anode substrate to achieve microalgae growth, nutrient removal and bioelectricity output without the addition of inorganic nutrients. It has the combined advantages of wastewater treatment, pollutant reduction, energy recovery and microalgae resource utilization.

[0041] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for rapid degradation of thiamethoxam contaminated domestic sewage by microalgae fuel cell, characterized in that, include: A dual-chamber microalgae fuel cell is provided, the dual-chamber microalgae fuel cell including an anode chamber, a cathode chamber, a proton exchange membrane disposed between the anode chamber and the cathode chamber, an anode electrode disposed in the anode chamber, a cathode electrode disposed in the cathode chamber, and an external circuit connecting the anode electrode and the cathode electrode; Anaerobic electrogenic microorganisms were inoculated into the anode chamber to construct an anode anaerobic system; Domestic sewage containing thiamethoxam was introduced into the cathode chamber, and Scenedesmus was inoculated into the cathode chamber to construct a cathode photosynthetic microalgae system; The cathode chamber is subjected to photochemical culturing, and the external circuit is kept closed during the photochemical culturing process. This allows the anaerobic system at the anode to oxidize organic matter and generate electrons and protons. The electrons are transferred to the cathode electrode via the external circuit, and the protons migrate to the cathode chamber via the proton exchange membrane. The Scenedessella in the cathode chamber produces oxygen through photosynthesis, which acts as an electron acceptor. An oxygen reduction reaction occurs on the surface of the cathode electrode. At the same time, the Scenedessella utilizes nutrients in the domestic sewage for growth, metabolism, and conversion of the thiamethoxam, thereby achieving the treatment of thiamethoxam-containing wastewater and bioelectricity output.

2. The method according to claim 1, characterized in that, In the step of providing a dual-chamber microalgae fuel cell, the dual-chamber microalgae fuel cell adopts a dual-chamber reactor, the anode chamber and the cathode chamber are separated by the proton exchange membrane, the anode electrode and the cathode electrode are both carbon paper electrodes, the external circuit connects the anode electrode and the cathode electrode through titanium wire, and an external resistor is connected in series in the external circuit and connected to a voltage recording device.

3. The method according to claim 1, characterized in that, In the step of inoculating the anode chamber with anaerobic electrogenic microorganisms, the anaerobic electrogenic microorganisms are derived from anaerobic wastewater from the anaerobic tank and sludge from the sludge pumping station of the wastewater treatment plant.

4. The method according to claim 1, characterized in that, In the step of introducing domestic sewage containing thiamethoxam into the cathode chamber, the initial concentration of thiamethoxam in the domestic sewage is from 1 mg / L to 10 mg / L.

5. The method according to claim 1, characterized in that, In the step of inoculating the cathode chamber with Scenedesmus sp. TXH strain, the inoculation amount of Scenedesmus is 0.1 g per liter based on cell dry weight.

6. The method according to claim 1, characterized in that, In the step of inoculating the cathode chamber with Scenedesmus, no additional inorganic nutrients are added to the cathode chamber, and the Scenedesmus utilizes the nitrogen, phosphorus and organic matter in the domestic sewage as a source of nutrients for growth.

7. The method according to claim 1, characterized in that, In the step of photo-culturing the cathode chamber, the culture temperature is 25 degrees Celsius, the light intensity is 40 micromoles per square meter per second, continuous photo-culturing is adopted, and the operation cycle is 6 days.

8. The method according to claim 1, characterized in that, The resistance of the external resistor connected in series in the external circuit is 1000 ohms.

9. The method according to claim 2, characterized in that, The carbon paper electrode measures 3 cm × 3 cm.

10. The method according to claim 2, characterized in that, The internal dimensions of each chamber of the dual-chamber microalgae fuel cell are 6 cm × 7 cm × 6 cm, and the working volume is 245 ml.

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