A microbial fuel cell - sequencing batch reactor - raceway oxidation pond combined aquaculture wastewater continuous treatment system and method

Abstract

The present application belongs to the technical field of sewage treatment, and specifically provides a water product cultivation wastewater continuous treatment system and method combined with a microbial fuel cell, a sequencing batch reactor and a runway type oxidation pond, wherein the sewage is treated by a biological method, the microorganisms used can be used as feed and agricultural fertilizer, the removal of organic matter, total nitrogen and total phosphorus can be enhanced, a large amount of pollutants can be converted into biomass energy, and the treatment capacity for water product cultivation wastewater containing nitrate nitrogen and nitrite nitrogen can be improved.The system combines a microbial fuel cell, a sequencing batch reactor and a runway type oxidation pond and other wastewater treatment systems, and can realize self-sufficiency of oxygen and carbon dioxide during the wastewater treatment implementation process, without external aeration.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and relates to a wastewater treatment method. Specifically, it relates to a continuous treatment system and method for aquaculture wastewater using a combination of microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond. Background Technology

[0002] Taking shrimp farming as an example, approximately 70% of the water used for aquaculture needs to be replaced daily during the later stages of the process. Therefore, aquaculture wastewater is a new source of pollution that has emerged alongside the rapid development of intensive land-based aquaculture, attracting widespread attention in recent years. Direct discharge of this wastewater can easily cause a surge in nitrogen and phosphorus levels in nearby natural water bodies, a major contributing factor to cyanobacterial blooms and red tides. Water pollution, in turn, significantly restricts the development of the aquaculture industry. How to achieve increased production without increased pollution in aquaculture is a pressing issue that the industry needs to address.

[0003] Aquaculture wastewater is classified as slightly polluted water, characterized by low pollution load, few types of pollutants (mainly nutrients such as nitrogen and phosphorus, and organic matter), and small fluctuations in pollutant concentration. However, it is characterized by large volume and concentrated generation time, making biological treatment suitable. Biological methods primarily utilize microorganisms and algae to absorb and degrade pollutants in aquaculture wastewater. These methods offer advantages such as cost-effectiveness and no secondary pollution, attracting widespread attention and research. Future research should focus on developing green and efficient biological treatment technologies tailored to the specific sources and characteristics of aquaculture wastewater, promoting the sustainable and healthy development of the aquaculture industry.

[0004] Environmental pollution and resource scarcity are two major challenges facing the world today. How to recover resources while treating wastewater has become a hot topic in environmental research. Considering the similarities between aquaculture wastewater and nutrient-rich wastewater, achieving resource recovery during wastewater treatment offers both economic and social benefits.

[0005] To address wastewater treatment issues, existing equipment and technologies are publicly available, such as microbial fuel cell technology, a wastewater resource recovery technology that treats wastewater while generating biomass energy. Current research has applied it to the treatment of high-concentration wastewater such as domestic sewage, aquaculture wastewater, food processing wastewater, and landfill leachate. Because it utilizes organic waste to generate electricity and convert it into usable biomass resources, it shows great promise in the treatment of nutrient-rich wastewater from food processing, aquaculture, and catering industries. However, existing technologies using microbial fuel cells for wastewater treatment suffer from low treatment efficiency and large sludge accumulation.

[0006] To address the aforementioned issues, Chinese patent CN 210367151 U discloses a novel microbial fuel cell coupled oxidation pond system, comprising an oxidation pond and a microbial fuel cell device. This patent integrates the microbial fuel cell and the oxidation pond into a single unit, with the anode and cathode of the microbial fuel cell respectively located in the anaerobic and aerobic zones of the oxidation pond, thereby improving the power generation efficiency of the microbial fuel cell. However, due to its structural limitations, this device can only perform batch processing, and the process requires aeration, resulting in significant energy consumption. Furthermore, the integration of the microbial fuel cell and the oxidation pond structure prevents effective recovery of biomass. Summary of the Invention

[0007] The purpose of this invention is to provide a continuous treatment system and method for aquaculture wastewater using a combination of microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond, aiming to solve the problems of low treatment efficiency, high energy consumption, and high carbon emissions in existing processes for aquaculture wastewater.

[0008] A continuous aquaculture wastewater treatment system combining a microbial fuel cell, a sequencing batch reactor, and a racetrack oxidation pond includes a microbial fuel cell, a sequencing batch reactor, and a racetrack oxidation pond.

[0009] The microbial fuel cell includes an anode chamber and a cathode chamber;

[0010] The anode chamber is connected to the sequencing batch reactor via a first outlet, and the sequencing batch reactor is further connected to the raceway oxidation pond; the cathode chamber is connected to the raceway oxidation pond via a second outlet.

[0011] Furthermore, the first water outlet and the second water outlet are respectively located on the lower side of the anode chamber and the cathode chamber; the first water inlet and the second water inlet are respectively located on the upper side of the anode chamber and the cathode chamber.

[0012] The first and second water inlets are at the same height and have the same inner diameter structure, and the first and second water outlets are at the same height and have the same inner diameter structure.

[0013] The anode and cathode chambers are cylindrical reactors of the same size, separated by a proton exchange membrane. The anode chamber includes an anode electrode and an anolyte; the cathode chamber includes a cathode electrode and a catholyte. The conductive material of the anode electrode is carbon felt, graphite felt, or graphite plate.

[0014] Furthermore, the anode chamber also includes an anode chamber cover plate, which has an anode chamber reference electrode fixing hole, an anode chamber sampling port, and an anode chamber wire hole; the cathode chamber also includes a cathode chamber cover plate, which has a cathode chamber reference electrode fixing hole, a cathode chamber sampling port, and a cathode chamber wire hole, thereby facilitating the measurement and sampling of various data. Gas pipe inlets are respectively provided on the anode chamber cover plate and the cathode chamber cover plate for inserting a gas balance tube, thereby connecting the anode chamber and the cathode chamber. CO2 generated in the anode chamber diffuses into the cathode chamber to promote photosynthesis of microalgae in the cathode chamber; O2 generated in the cathode chamber diffuses into the anode chamber to promote the rapid growth of photosynthetic bacteria and reduce COD, total nitrogen (TN), and total phosphorus (TP) values.

[0015] The sequencing batch reactor includes a removable top cover, an inlet, and an outlet, serving as a subsequent treatment reactor for the anolyte.

[0016] The anode chamber and the cathode chamber are made of transparent material, and the removable top cover is also made of transparent material. More preferably, the sequencing batch reactor is cylindrical, and the height-to-diameter ratio of the sequencing batch reactor is 1.5-2:1.

[0017] The racetrack-shaped oxidation pond includes: a first racetrack reaction tank, a second racetrack reaction tank, and a third racetrack reaction tank; the first racetrack reaction tank includes a first racetrack high platform and a first racetrack low platform, which are connected by a ramp; similarly, the second racetrack reaction tank includes a second racetrack high platform and a second racetrack low platform, which are connected by a ramp; the third racetrack reaction tank includes a third racetrack high platform and a third racetrack low platform, which are connected by a ramp.

[0018] Furthermore, the first high platform of the runway is connected end to end with the second low platform of the runway, the second high platform of the runway is connected end to end with the third low platform of the runway, and finally, water is discharged from the runway-shaped oxidation pond outlet at the third high platform of the runway.

[0019] Furthermore, the first outlet is connected to the inlet of the sequencing batch reactor via a pipeline, and the pipeline at the outlet of the sequencing batch reactor is connected to the pipeline at the second outlet and converges at the low platform of the first runway.

[0020] The racetrack-shaped oxidation pond also includes a removable top cover, which is light-transmitting.

[0021] This invention also provides a continuous treatment method for aquaculture wastewater using a combination of microbial fuel cell, sequencing batch reactor (SBR), and racetrack oxidation pond. The microbial fuel cell reduces the concentrations of organic pollutants, ammonium nitrogen, and total phosphorus (TP), while generating a large amount of usable biomass. Subsequently, the anolyte flows into the SBR to further reduce the content of nitrate nitrogen, nitrite nitrogen, and TP. The catholyte flows into an outdoor, enclosed racetrack oxidation pond, where photosynthesis produces high levels of dissolved oxygen. Finally, the liquid from the SBR enters the outdoor racetrack oxidation pond and mixes with the catholyte to further reduce the concentrations of organic matter, total nitrogen (TN), and TP. After passing through three racetrack reaction tanks, the wastewater meets emission standards.

[0022] Specifically, the processing method is as follows:

[0023] Aquaculture wastewater is added to the microbial fuel cell. After intermittent startup and operation for 48–96 hours, continuous water intake begins from the first and second inlets, with a hydraulic retention time of 8–16 hours. The anolyte is sent from the first outlet to the sequencing batch reactor (SBR). After a hydraulic retention time of 12–24 hours, the catholyte is sent from the second outlet to a racetrack oxidation pond. After treatment in the SBR for 12–24 hours, the treated anolyte is sent from the SBR outlet to the racetrack oxidation pond. The catholyte and anolyte from the SBR meet discharge standards after 12–72 hours in the racetrack oxidation pond.

[0024] Preferably, the water inlet rate of the first inlet is 0.833 to 1.67 mL / min; and the water inlet rate of the second inlet is 0.55 to 1.11 mL / min.

[0025] Preferably, the water flow rate of the first outlet is 0.833 to 1.67 mL / min; and the water flow rate of the second outlet is 0.55 to 1.11 mL / min.

[0026] Both the anolyte and the catholyte are aquaculture wastewater. The microbial fuel in the anode chamber and the cathode chamber occupies 3 / 4 to 4 / 5 of their respective volumes, and the gas space above the microbial fuel in the anode chamber and the cathode chamber occupies 1 / 5 to 1 / 4 of their respective volumes.

[0027] The microorganisms inoculated in the anode chamber are photosynthetic bacteria, the microorganisms inoculated in the cathode chamber are microalgae, and the reaction substrate is aquaculture wastewater.

[0028] Preferably, the microalgae is Chlorella; preferably, the photosynthetic bacteria are denitrifying photosynthetic bacteria; more preferably, the denitrifying photosynthetic bacteria are nitrogen-fixing red bacteria.

[0029] The inoculum amount of the microalgae is 5-10%; the inoculum amount of the photosynthetic bacteria is 2-8%.

[0030] The treatment process of the continuous aquaculture wastewater treatment system combining a microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond sequentially involves a microbial fuel cell, a sequencing batch reactor, and a racetrack oxidation pond. This order is chosen because the microorganisms used in this invention are photosynthetic bacteria and Chlorella, which have relatively slow growth rates. The microbial fuel cell can accelerate their growth and accumulation, while also providing preliminary treatment for the wastewater. As the photosynthetic bacteria culture (anolyte) enters the sequencing batch reactor, continuous denitrification occurs under anoxic and natural light conditions, thereby reducing nitrate and nitrite nitrogen in the wastewater. The treated liquid flowing out of the sequencing batch reactor, along with the Chlorella culture (catholyte), enters the racetrack oxidation pond for further treatment.

[0031] When treating aquaculture wastewater in the anode chamber, the pH of the anolyte will decrease slightly under normal circumstances, with the normal pH range being 6.5-7.2.

[0032] When treating aquaculture wastewater in the anolyte, dissolved oxygen levels may be too low. This is because photosynthetic bacteria consume dissolved oxygen through the proliferation of carbon sources and increase the activity of enzymes related to denitrification. The normal range for dissolved oxygen in the solution is 0.5-2.0 mg / L. If dissolved oxygen falls below 0.5 mg / L, the dissolved oxygen level can be appropriately increased by increasing the stirring rate.

[0033] pH fluctuations occur when treating aquaculture wastewater in the cathode chamber. Before treatment, adding 2 g / L sodium bicarbonate helps reduce pH fluctuations and provides a cost-effective inorganic carbon source. The pH should not exceed 9.0 before microalgae begin photosynthesis in the cathode chamber to avoid affecting the activity of photosynthetic enzymes. The normal pH range before startup is 8.0-8.6. Microalgae are sensitive to acidity; their activity is inhibited when the solution pH drops to 6.5; when the solution pH drops to 6.0, the chlorophyll in the microalgae is destroyed, causing the algae to turn yellowish-white and easily settle. If a pH decreases, sodium bicarbonate can be added appropriately to stabilize the pH; the suitable pH range is 7.2-7.8.

[0034] In the initial stage of aquaculture wastewater treatment in the cathode chamber, microalgae rapidly reproduce by utilizing the organic matter in the wastewater, leading to a rapid decrease in dissolved oxygen. After 48 hours, microalgal photosynthesis begins, significantly increasing dissolved oxygen levels to the saturation oxygen level at that temperature, within the normal range of 10-12 mg / L. If the dissolved oxygen level in the cathode chamber remains below 0.2 mg / L for an extended period, it may indicate poor microalgal activity.

[0035] Beneficial effects:

[0036] 1. The wastewater continuous treatment system combining microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond provided by this invention accelerates the treatment speed of aquaculture wastewater, converts organic pollutants into biomass energy, and improves the treatment capacity for aquaculture wastewater with high nitrate nitrogen and nitrite nitrogen content. The entire process is a continuous wastewater treatment mode and does not require aeration, achieving self-sufficiency of oxygen and carbon dioxide within the system.

[0037] 2. This invention uses a racetrack-type oxidation pond with a slope, which causes local backflow of the water layer at the bottom of the racetrack-type oxidation pond at the slope. By controlling the influent flow rate, microorganisms can be effectively intercepted, maintaining a high efficiency in wastewater treatment.

[0038] 3. In the wastewater treatment method combining microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond provided by this invention, the microorganisms used in the microbial fuel cell are microalgae and photosynthetic bacteria. The microalgae generate oxygen through photosynthesis, while the denitrification of the photosynthetic bacteria replaces the anaerobic digestion of traditional sludge, thereby reducing sludge production. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a microbial fuel cell;

[0040] Figure 2 This is a photograph of a microbial fuel cell in operation.

[0041] Figure 3 This is a schematic diagram of a racetrack-type oxidation pond.

[0042] Figure 4 The diagram shows the top view and cross-sectional view of a racetrack-type oxidation pond.

[0043] Figure 5 This is a diagram of a continuous wastewater treatment system that combines a microbial fuel cell, a sequencing batch reactor, and a racetrack-type oxidation pond.

[0044] In the diagram: 1-Anode chamber, 2-Cathode chamber, 3-Anode electrode, 4-Cathode electrode, 5-Anodic solution, 6-Cathode solution, 7-First inlet, 8-Second inlet, 9-First outlet, 10-Second outlet, 11-Anode chamber cover, 12-Cathode chamber cover, 13-Anode reference electrode fixing hole, 14-Cathode reference electrode fixing hole, 15-Anode conductor, 16-Cathode conductor, 17-Anode conductor hole, 18-Cathode conductor hole, 19-Anode top inlet, 20-Cathode top inlet, 21-Anode sampling port, 22-Cathode sampling port, 23-Liftable support 24-Magnetic stirrer, 25-Proton exchange membrane, 26-Gas balance tube, 27-Gas pipe inlet, 28-External circuit, 29-Rotor, 30-Racetrack oxidation pond, 31-Sequencing batch reactor inlet, 32-Sequencing batch reactor, 33-Sequencing batch reactor outlet, 34-Sequencing batch reactor removable top cover, 35-Racetrack oxidation pond removable top cover, 36-Second racetrack high platform, 37-Racetrack oxidation pond inlet, 38-First racetrack low platform, 39-Second racetrack low platform, 40-Racetrack oxidation pond outlet, 41-First racetrack high platform, 42-Third racetrack low platform, 43-Third racetrack high platform. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] like Figure 1 and Figure 2 As shown, the microbial fuel cell of the present invention includes an anode chamber 1, a cathode chamber 2, a proton exchange membrane 25, and a magnetic stirrer 24. The inner cavities of the anode chamber 1 and the cathode chamber 2 are connected. The proton exchange membrane 25 is located at the junction of the anode chamber 1 and the cathode chamber 2, and separates the inner cavities of the anode chamber 1 and the cathode chamber 2.

[0047] The anode chamber 1 contains an anode electrode 3, and the cathode chamber 2 contains a cathode electrode 4. The anode electrode 3 is connected to an anode wire 15 and then to the cathode electrode 4 via an external circuit 28 and a cathode wire 16. The conductive material of the anode electrode 3 is carbon felt.

[0048] The anode chamber 1 has an anode chamber cover plate 11 at the upper end. The anode chamber cover plate 11 is provided with an anode chamber reference electrode fixing hole 13, an anode chamber wire hole 17, and an anode chamber top water inlet 19. The anode wire 15 passes through the anode chamber 1 through the anode chamber wire hole 17.

[0049] The cathode chamber 2 has a cathode chamber cover plate 12 at the upper end. The cathode chamber cover plate 12 is provided with a cathode chamber reference electrode fixing hole 14, a cathode chamber wire hole 18, and a cathode chamber top water inlet 20. The cathode wire 16 passes through the cathode chamber wire hole 18 and exits the cathode chamber 2.

[0050] The anode chamber 1 and cathode chamber 2 are supported by a liftable bracket 23, and a magnetic stirrer 24 is provided below the anode chamber 1 and cathode chamber 2 respectively. Correspondingly, a rotor 29 is placed in the anode chamber 1 and cathode chamber 2 respectively.

[0051] The upper side of the anode chamber 1 and the cathode chamber 2 are respectively provided with a first water inlet 7 and a second water inlet 8, and the lower side is respectively provided with a first water outlet 9 and a second water outlet 10. The first water inlet 7 and the second water inlet 8 are at the same height and have the same inner diameter structure, and the first water outlet 9 and the second water outlet 10 are at the same height and have the same inner diameter structure.

[0052] The sequencing batch reactor 32 includes a removable top cover 34, an inlet 31, and an outlet 33, serving as a post-treatment reactor for micro-oxygen in the anolyte.

[0053] like Figure 3 and Figure 4 As shown, the racetrack-type oxidation pond includes: a first racetrack reaction tank, a second racetrack reaction tank, and a third racetrack reaction tank; the first racetrack reaction tank includes a first racetrack high platform 41 and a first racetrack low platform 38, which are connected by a ramp; similarly, the second racetrack reaction tank includes a second racetrack high platform 36 and a second racetrack low platform 39, which are connected by a ramp; the third racetrack reaction tank includes a third racetrack high platform 43 and a third racetrack low platform 42, which are connected by a ramp.

[0054] Furthermore, water enters through the raceway-type oxidation pond inlet 37 at the first raceway low platform 38, the first raceway high platform 41 is connected to the second raceway low platform 39 end to end, the second raceway high platform 36 is connected to the third raceway low platform 42 end to end, and finally, water exits through the raceway-type oxidation pond outlet 40 at the third raceway high platform 43.

[0055] Furthermore, the first outlet 7 is connected to the inlet 31 of the sequencing batch reactor via a pipeline, and the pipeline at the outlet 33 of the sequencing batch reactor is connected to the pipeline at the second outlet 10 and then converges at the low platform 38 of the first runway.

[0056] The racetrack-shaped oxidation pond also includes a detachable top cover 35, which is light-transmitting.

[0057] All raw materials used in the following examples are commercially available products. Chlorella was purchased from Qingdao Xuneng Biotechnology Co., Ltd., and nitrogen-fixing red bacteria ATCC 17025 was purchased from the American Type Culture Collection.

[0058] Example

[0059] like Figure 5 As shown, both the anode chamber 1 and the cathode chamber 2 are filled with microbial fuel; the microbial fuel is aquaculture wastewater, which has a pH between 7.0 and 8.0, a COD of 400-800 mg / L, nitrate nitrogen of 14-19 mg / L, nitrite nitrogen of 2-5 mg / L, ammonia nitrogen of 14-21 mg / L, and phosphorus of 37-42 mg / L.

[0060] The anode chamber 1 is inoculated with nitrogen-fixing red bacteria; the cathode chamber 2 is inoculated with Chlorella, the reaction substrate is aquaculture wastewater, and the culture is carried out under natural light for 12 hours a day.

[0061] The preparation method of seed culture medium for anodic nitrogen-fixing red bacteria is as follows: weigh 3g of glucose, 8g of yeast powder, 2g of sodium chloride, 0.125g of magnesium sulfate, 1.3g of potassium dihydrogen phosphate, add 1mL of growth factor stock solution, add deionized water to 1L, adjust the pH to 7.2, and sterilize at 121℃ for 20min.

[0062] The inoculum size of the nitrogen-fixing red bacteria seed was 8%. The culture method for the nitrogen-fixing red bacteria seed inoculum was as follows: culture at 30℃ and 200 r / min for 72 h, until the absorbance OD... 600 The concentration was set to 5.0, resulting in a viable bacterial count of 2.5 × 10⁻⁶ in the culture medium. 9 CFU / mL or higher. Then, 8% (v / v) of nitrogen-fixing red bacteria seed culture was inoculated into anode chamber 1, with an initial absorbance OD... 600 It is 0.40.

[0063] The preparation method of the seed culture medium for Chlorella cathodicis is as follows: 1.70g of BG11 medium, 1.5g of glucose, 1g of sodium bicarbonate, and a final volume of 1L are added. The pH is adjusted to 7.6, and the medium is sterilized at 121℃ for 20min.

[0064] The inoculum size of the Chlorella seeds was 10%. The cultivation method for the Chlorella seed inoculum was as follows: culturing at 30℃ and 120 r / min for 120 h until the absorbance OD540 reached 3.0, and the viable algae in the culture medium reached 5 × 10⁻⁶. 7 Amounts of 10% (v / v) Chlorella seed culture were then inoculated into the cathode chamber, with an initial absorbance OD of [missing value]. 540 It is 0.3.

[0065] After adding aquaculture wastewater, the microbial fuel in the anode and cathode chambers occupies 4 / 5 of their respective volumes.

[0066] In this embodiment, 800 mL of aquaculture wastewater is added to the microbial fuel cell through the anode chamber top inlet 19 and the cathode chamber top inlet 20, respectively. Once the microbial fuel cell starts operating, denitrification occurs in the anode chamber 1. Nitrogen-fixing red bacteria oxidize and decompose a large amount of organic matter under microaerobic conditions, producing CO2, protons, and electrons. A portion of these electrons are converted into NO3-. - As an electron acceptor, it is reduced to N2; another portion of electrons are transferred from the external circuit to the cathode reaction electrode 4 through the anode wire 15. Simultaneously, the CO2 produced in the anode chamber can serve as a raw material for photosynthesis in the cathode chamber, while the O2 produced by microalgae in the cathode chamber further promotes the reduction of COD in the anode chamber, forming a material cycle within the system. After the microalgae initiate photosynthesis in the cathode chamber, the pH gradually increases. Therefore, the retention time of aquaculture wastewater should not be too long, and should not exceed 96 hours during the intermittent start-up operation phase to prevent the pH value of the treated water from exceeding the standard. Experimental tests showed that after photosynthesis, the pH of the cathode-grown Chlorella can reach a maximum of 10-11 while still maintaining strong photosynthetic activity and high dissolved oxygen levels. Microscopic examination showed that the cells were in good condition. Using continuous influent, the anode chamber completed the treatment of 10-15 mg / L of ammonia nitrogen in the wastewater within 72 hours during the intermittent start-up operation phase, reducing it to less than 5 mg / L. The cathode chamber maintained a high dissolved oxygen level of 10.65 mg / L after 72 hours.

[0067] In this embodiment, after a 72-hour start-up period, water is continuously fed into the system through the first inlet 7 and the second inlet 8. The inlet rate at the first inlet 7 is 1.15 mL / min (hydraulic retention time 12 h), and the inlet rate at the second inlet 8 is 0.833 mL / min (hydraulic retention time 16 h). Subsequently, the first outlet 7 pumps the anolyte 5 to the sequencing batch reactor 32 at a rate of 1.15 mL / min, and the second outlet 8 pumps the catholyte 6 to the racetrack oxidation pond 30 at a rate of 0.833 mL / min using a peristaltic pump. Finally, the treated anolyte flows from the sequencing batch reactor 32 to the racetrack oxidation pond 30 at a rate of 1.15 mL / min (hydraulic retention time 12 h), completing the water intake process. The aquaculture wastewater is continuously treated by the combined microbial fuel cell-sequencing batch reactor-racetrack oxidation pond treatment system to meet national discharge standards.

Claims

1. A continuous aquaculture wastewater treatment device combining a microbial fuel cell, a sequencing batch reactor, and a racetrack oxidation pond, characterized in that, This includes microbial fuel cells, sequencing batch reactors, and racetrack oxidation ponds; The racetrack-style oxidation pond is an oxidation pond with a slope; The microbial fuel cell includes an anode chamber and a cathode chamber; a first water outlet and a second water outlet are respectively provided on the lower side of the anode chamber and the cathode chamber; a first water inlet and a second water inlet are respectively provided on the upper side of the anode chamber and the cathode chamber. The sequencing batch reactor includes a removable top cover, an inlet, and an outlet. The anode chamber is connected to the sequencing batch reactor via the first outlet, and the sequencing batch reactor is connected to the racetrack-type oxidation pond. The cathode chamber is connected to the racetrack-shaped oxidation pond via a second outlet. The racetrack-shaped oxidation pond includes: a first racetrack reaction tank, a second racetrack reaction tank, and a third racetrack reaction tank; the first racetrack reaction tank includes a first racetrack high platform and a first racetrack low platform, which are connected by a ramp; similarly, the second racetrack reaction tank includes a second racetrack high platform and a second racetrack low platform, which are connected by a ramp; the third racetrack reaction tank includes a third racetrack high platform and a third racetrack low platform, which are connected by a ramp. A raceway-type oxidation pond inlet is provided at the low platform of the first raceway, and a raceway-type oxidation pond outlet is provided at the high platform of the third raceway. The first runway high platform is connected end-to-end with the second runway low platform, and the second runway high platform is connected end-to-end with the third runway low platform. The microorganisms inoculated in the anode chamber are photosynthetic bacteria, the microorganisms inoculated in the cathode chamber are microalgae, and the reaction substrate is aquaculture wastewater. The microalgae are Chlorella; the photosynthetic bacteria are denitrifying photosynthetic bacteria, and the photosynthetic bacteria are nitrogen-fixing red bacteria.

2. The continuous aquaculture wastewater treatment device combining microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond according to claim 1, characterized in that, The anode chamber and the cathode chamber are made of transparent material, and the removable top cover of the sequencing batch reactor is also made of transparent material.

3. The continuous aquaculture wastewater treatment device combining microbial fuel cell-sequencing batch reactor-racetrack oxidation pond according to claim 1, characterized in that, The sequencing batch reactor is cylindrical, and its height-to-diameter ratio is 1.5-2:

1.

4. The continuous aquaculture wastewater treatment device combining microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond according to claim 2, characterized in that, The anode chamber includes an anode chamber cover plate, which is provided with an anode chamber reference electrode fixing hole, an anode chamber top water inlet, an anode chamber sampling port, and an anode chamber wire hole. The cathode chamber includes a cathode chamber cover plate, which is provided with a cathode chamber reference electrode fixing hole, a cathode chamber top water inlet, a cathode chamber sampling port, and a cathode chamber wire hole.

5. The continuous aquaculture wastewater treatment device combining microbial fuel cell, sequencing batch reactor, and racetrack oxidation pond according to claim 1, characterized in that, The racetrack-shaped oxidation pond includes a removable top cover, which is light-transmitting.

6. A continuous treatment method for aquaculture wastewater using a combination of microbial fuel cell-sequencing batch reactor-racetrack oxidation pond, characterized in that, The aquaculture wastewater is treated using a continuous treatment device combining a microbial fuel cell, a sequencing batch reactor (SBR), and a racetrack oxidation pond as described in any one of claims 1 to 5. The microbial fuel cell reduces the concentration of organic pollutants and generates biomass. Subsequently, the anolyte flows into the SBR to further reduce the content of nitrate nitrogen and total phosphorus. The catholyte flows into an outdoor enclosed racetrack oxidation pond to generate higher dissolved oxygen levels through photosynthesis. Finally, the treated anolyte from the SBR enters the outdoor racetrack oxidation pond and mixes with the catholyte. After a period of time, the mixture meets the discharge standards.

7. The continuous treatment method for aquaculture wastewater using a combination of microbial fuel cell-sequencing batch reactor-racetrack oxidation pond as described in claim 6, characterized in that, The specific treatment process is as follows: Aquaculture wastewater is added to the microbial fuel cell. After intermittent startup and operation for 48-96 hours, water is continuously introduced from the first and second inlets and retained for 8-16 hours. The anolyte is then sent from the first outlet to the sequencing batch reactor (SBR). After a retention period of 12-24 hours, the catholyte is sent from the second outlet to the raceway oxidation pond. After treatment in the SBR for 12-24 hours, the treated anolyte is sent from the SBR outlet to the raceway oxidation pond. The anolyte and the treated anolyte meet the discharge standards after 12-72 hours.

8. The continuous treatment method for aquaculture wastewater using a combination of microbial fuel cell-sequencing batch reactor-racetrack oxidation pond as described in claim 7, characterized in that, The water inlet rate of the first inlet is 0.833~1.67 mL / min; the water inlet rate of the second inlet is 0.55~1.11 mL / min; The water flow rate of the first outlet is 0.833~1.67 mL / min; the water flow rate of the second outlet is 0.55~1.11 mL / min.

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