A self-driven sewage treatment device and a method of using the same

Abstract

The present application relates to sewage treatment equipment technical field, specifically disclose a kind of self-driving sewage treatment device and its using method, device contains first reaction column, it is filled with first anoxic biological filler layer, anoxic electrochemical filler layer and second anoxic biological filler layer, the first working water level line higher than the top of first anoxic biological filler layer is arranged;Second reaction column is filled with aerobic biological filler layer, aerobic electrochemical filler layer and third anoxic biological filler layer, the second working water level line is arranged between the top of aerobic electrochemical filler layer and the top of aerobic biological filler layer;Wherein, device is also laid with treatment waterway and reuse waterway;Anoxic electrochemical filler layer and aerobic electrochemical filler layer are electrically connected.The present application makes full use of the function complementation of electrochemical filler and biological filler and the difference between electrochemical filler in different regions, can be driven without external power supply, to realize the efficient collaborative removal of nitrogen and phosphorus in sewage.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment equipment technology, specifically to a wastewater treatment device that can remove phosphorus and nitrogen without the need for external energy. Background Technology

[0002] Bioelectrochemical systems are a commonly used wastewater treatment method. They mainly enhance the oxidation-reduction reaction of pollutants and thus remove them by transferring extracellular electrons between electroactive microorganisms and solid electrodes.

[0003] One of the commonly used bioelectrochemical systems in wastewater treatment is the microbial fuel cell. However, microbial fuel cells have several drawbacks, such as low power density, high cost of precious metal / carbon felt electrodes, and a tendency for internal resistance to surge after scale-up. Other bioelectrochemical systems, such as microbial electrolyzers, require an external 0.2~1.2 V DC power supply during operation, resulting in additional power consumption. Furthermore, long-term use is accompanied by problems such as ion exchange membrane fouling and electrode passivation.

[0004] In general, current common microbial electrochemical systems are still constrained by bottlenecks such as reliance on external energy, expensive electrode materials, and difficulties in engineering scale-up. Therefore, there is an urgent need for a bioelectrochemical system and device that requires no power input, uses inexpensive electrode materials, has a simple reactor structure, and can efficiently treat nitrogen and phosphorus elements in actual wastewater. Summary of the Invention

[0005] One of the objectives of this invention is to provide a self-driven wastewater treatment device that can remove nitrogen and phosphorus from wastewater without requiring an external power input.

[0006] The second objective of this invention is to provide a method for using the aforementioned self-driven wastewater treatment device to ensure its normal operation.

[0007] Firstly, the present invention is achieved through the following technical solution:

[0008] A self-driven wastewater treatment device includes: a first reaction column, which is filled from top to bottom with a first anoxic biological packing layer, an anoxic electrochemical packing layer, and a second anoxic biological packing layer, and a first working water level line is set in the first reaction column, which is higher than the top of the first anoxic biological packing layer; and a second reaction column, which is filled from top to bottom with an aerobic biological packing layer, an aerobic electrochemical packing layer, and a third anoxic biological packing layer, and a second working water level line is set in the second reaction column, which is located above the aerobic electrochemical packing layer. Between the top of the anoxic biological packing layer and the aerobic biological packing layer; wherein, the device is provided with a treated water circuit and a reclaimed water circuit; the treated water circuit is sequentially connected to the first anoxic biological packing layer, the anoxic electrochemical packing layer, the second anoxic biological packing layer, the aerobic biological packing layer, the aerobic electrochemical packing layer, and the third anoxic biological packing layer; one end of the reclaimed water circuit is connected to the first reaction column, and the other end is connected to the reflux port of the second reaction column, the reflux port being opened between the second working water level line and the top of the aerobic electrochemical packing layer; the anoxic electrochemical packing layer and the aerobic electrochemical packing layer are electrically connected.

[0009] In this invention, electrochemical packing materials (such as iron-carbon materials) and biological packing materials (such as volcanic rock materials) work together to remove pollutants. The biological packing materials carry various microorganisms capable of denitrification, thus removing pollutants such as total nitrogen from wastewater; however, they typically lack phosphorus removal capabilities. The electrochemical packing materials, on the other hand, enhance the biodegradability of recalcitrant wastewater through micro-electrolysis, thereby improving the wastewater treatment performance of the biological packing materials. Furthermore, the oxidation products of some electrochemical materials can react with phosphates to achieve phosphorus removal. This achieves a synergistic effect between the functions of the electrochemical and biological packing materials. Specifically, for example, in anoxic environments, the electrochemical packing materials can provide electron donors for denitrification using micro-electrolysis, thus achieving and enhancing nitrogen removal. In aerobic environments, the oxidation products of the electrochemical packing materials can precipitate phosphates in the wastewater, achieving the desired phosphorus removal effect.

[0010] In this invention, a first reaction column and a second reaction column are first arranged to form the required anoxic and aerobic reaction zones in the wastewater treatment device. The first working water level in the first reaction column is higher than the top of the first anoxic biological packing layer. Therefore, during operation of the wastewater treatment device, the wastewater submerges all the packing material in the reaction column, allowing the bioelectrochemical reaction to occur in an anoxic environment, thus forming an anoxic reaction zone within the first reaction column. The second working water level in the second reaction column is positioned between the top of the aerobic electrochemical packing layer and the top of the aerobic biological packing layer. This allows the top portion of the aerobic biological packing layer in the second reaction column to be exposed and fully exposed to air. Furthermore, during the process of wastewater being introduced into the second reaction column, sufficient oxygen can dissolve before the wastewater falls to the second working water level, ensuring that the electrochemical packing layer in the second reaction column remains under aerobic conditions during the reaction, thus forming an aerobic reaction zone within the second reaction column. In this way, although both sets of reaction columns contain electrochemical and biological packing materials, they are used to reduce total nitrogen and total phosphorus in the wastewater, respectively.

[0011] Based on the above structure, this invention establishes an electrical connection between the electrochemical packing layers in the two reaction zones to further promote coordination and cooperation between them, thereby eliminating the need for external energy. Specifically, during wastewater treatment, the wastewater in the aerobic reaction zone undergoes an electrochemical reaction with the materials in the aerobic electrochemical packing layer. For example, when the electrochemical packing material used is iron-carbon, the wastewater in the aerobic reaction zone oxidizes the zero-valent iron in the iron-carbon to trivalent iron, releasing electrons in the process. However, this reaction does not occur in the anoxic reaction zone. This creates a significant potential difference between the electrochemical packing layers in the aerobic and anoxic reaction zones. Again, taking iron-carbon as the electrochemical packing material as an example, during the operation of the wastewater treatment device, a potential difference of 300-500 mV can be formed between the aerobic iron-carbon packing layer in the second reaction column and the anoxic iron-carbon packing layer in the first reaction column. Therefore, when the present invention establishes an electrical connection between the two through components such as wires, a potential difference of 30-60 mA / m can be generated between them. 3 The current is used to transfer electrons generated in the aerobic iron-carbon packing layer to the anoxic iron-carbon packing layer, and then these electrons can participate in the denitrification reaction of microorganisms in the anoxic biological packing layer in the anoxic reaction zone.

[0012] Meanwhile, this invention also incorporates reclaimed water channels in both reaction zones to further promote the synergistic utilization of the liquid phases. Specifically, in the aerobic reaction zone, microorganisms on the biological packing material undergo nitrification with the wastewater, converting ammonia nitrogen into nitrate. This nitrate is then channeled back into the anoxic reaction zone via the reclaimed water channels, where it undergoes heterotrophic denitrification under anoxic conditions, further reducing the total nitrogen content in the anoxic reaction zone.

[0013] Through the above-described structure of the wastewater treatment device, this invention connects and coordinates the originally independent bioelectrochemical reactions in the aerobic and anoxic reaction zones, making full use of the excess electrons and nitrates generated in the aerobic reaction zone. This allows the wastewater treatment device to simultaneously carry out nitrogen and phosphorus removal without an external power source, greatly reducing the operating cost of wastewater treatment and ensuring a high removal rate for phosphorus and nitrogen.

[0014] As a further improvement of the present invention, the first anoxic biological packing layer, the second anoxic biological packing layer, the aerobic biological packing layer and the third anoxic biological packing layer are all composed of volcanic rock packing.

[0015] As a further improvement of the present invention, the particle size of the volcanic rock filler is 5~8mm.

[0016] As a further improvement of the present invention, both the anoxic electrochemical packing layer and the aerobic electrochemical packing layer are composed of iron-carbon packing.

[0017] As a further improvement of the present invention, the particle size of the iron-carbon filler is 3~5mm; the iron content is 75±5%.

[0018] As a further improvement of the present invention, the main components of the iron-carbon filler are zero-valent iron and graphite carbon.

[0019] Overall, the biological and electrochemical fillers used in this invention are readily available and low-cost materials, so as to achieve the aforementioned nitrogen and phosphorus removal effects with low material costs.

[0020] As a further improvement of the present invention, the height of the return port is higher than the height of the first working water level. With this structure, the nitrate-containing liquid phase generated in the aerobic biological packing layer can flow back to the first reaction column by gravity, thereby reducing the need for a transfer pump in the return water path, further reducing the overall power consumption of the wastewater treatment device, and lowering operating costs.

[0021] As a further improvement of the present invention, the volume ratio of the anoxic electrochemical packing layer to the aerobic electrochemical packing layer is 1:(1.2~3). Based on the different micro-electrolysis intensity requirements during the bioelectrochemical reaction during nitrogen and phosphorus removal, and considering the potential difference requirements between the electrochemical packing layers in the first and second reaction columns, the amount of anoxic and aerobic electrochemical packing layers is controlled in this invention to ensure the normal progress of the aforementioned electron migration and the smooth implementation of nitrogen and phosphorus removal from wastewater.

[0022] As a further improvement of the present invention, the hydraulic retention time ratio between the first reaction column and the second reaction column is 1:(2~5). Since the first reaction column mainly participates in nitrogen removal and the second reaction column mainly participates in phosphorus removal, and the rates of chemical reactions differ between the nitrogen and phosphorus removal processes, the present invention limits the hydraulic retention time of wastewater in the first and second reaction columns to achieve a balance between the two. Specifically, for example, both the first and second reaction columns can be controlled to have cylindrical structures with the same cross-sectional diameter, but different heights to achieve different hydraulic retention times.

[0023] As a further improvement of the present invention, a water distribution device is arranged in the water treatment circuit for inputting the wastewater to be treated into the second reaction column.

[0024] The water distribution device can evenly distribute wastewater across the cross-section of the second reaction column when it is fed into the column. This avoids the wastewater from concentrating only in a portion of the aerobic biological packing material during its descent, thus preventing the waste of the remaining aerobic biological packing material. Furthermore, the water distribution device can disperse the wastewater into small-diameter water droplets, allowing them to fully contact and dissolve enough oxygen during their descent, thus ensuring aerobic conditions for subsequent reactions.

[0025] Secondly, the present invention provides a method for using a self-driven wastewater treatment device to drive the operation of any of the above-mentioned self-driven wastewater treatment devices, comprising at least the following steps: S1. Activation step: continuously inputting wastewater to be treated into the first reaction column; firstly, keeping the return water path and the outward flow water path at the bottom of the first reaction column closed until the liquid level in the first reaction column reaches the first working water level line; then opening the water path between the first reaction column and the second reaction column while keeping the outward flow water path at the bottom of the second reaction column closed until the liquid level in the second reaction column reaches the second working water level line; finally, opening the water path at the bottom of the second reaction column; S2. Circulation step: continuously inputting wastewater into the first reaction column while simultaneously opening the return water path; during this period, maintaining the flow rate of wastewater input into the first reaction column at 1~3Q, the flow rate of wastewater input into the second reaction column at 4~8Q, the flow rate of the return liquid in the return water path at 3~9Q, the flow rate of the treated liquid output from the second reaction column at 1~3Q, and the hydraulic residence time of the waste liquid in the self-driven wastewater treatment device at 10~16h.

[0026] The beneficial effects of this invention include:

[0027] (1) It makes full use of the functional complementarity between electrochemical packing and biological packing and the differences between electrochemical packing in different areas; specifically, it uses the electron donor generated by the micro-electrolysis reaction in the aerobic reaction zone to enhance the denitrification nitrogen removal in the anoxic reaction zone, and at the same time, it uses the electrochemical oxidation products in the aerobic reaction zone to achieve chemical precipitation phosphorus removal; thus, it can achieve efficient synergistic removal of nitrogen and phosphorus in wastewater without the need for external power supply, avoids the dependence of traditional bioelectrochemical systems on external power supply, and significantly reduces operating energy consumption.

[0028] (2) The device has a simple structure, and in the selection of packing materials inside the first and second reaction columns, inexpensive and readily available volcanic rock biological packing materials and iron-carbon electrochemical packing materials are used, which greatly reduces the material cost of the sewage treatment device.

[0029] (3) By setting up a reclaimed water path and optimizing the hydraulic retention time ratio and electrochemical packing layer volume ratio in the reaction column, an efficient wastewater treatment process was constructed, which further improved the removal efficiency of total nitrogen and total phosphorus.

[0030] (4) No complex control system is required during operation. Stable operation can be achieved simply by adjusting the water level and flow rate. Furthermore, the return water circuit utilizes gravity to reduce the demand for power equipment, making the overall operation of the sewage treatment device simple and the maintenance cost low, which is conducive to its promotion and use. Attached Figure Description

[0031] The accompanying drawings are provided below to illustrate the preferred embodiments of the invention and to aid in understanding the objectives and advantages of the invention, wherein:

[0032] Figure 1 This is a schematic diagram of a self-driven wastewater treatment device.

[0033] Figure 2 This is a statistical chart showing the removal efficiency of total nitrogen and total phosphorus during the operation of a self-driven wastewater treatment device.

[0034] in Figure 2 (a) in the figure is a statistical chart of total nitrogen removal efficiency. Figure 2 (b) in the figure is a statistical chart of total phosphorus removal effect. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0037] Example 1:

[0038] This embodiment provides a self-driven wastewater treatment device, comprising a first reaction column 1 and a second reaction column 2. For example, in this embodiment, the first reaction column 1 has a height of 60 cm and a volume of 10.6 L; the second reaction column 2 has a height of 120 cm and a volume of 21.2 L. In this embodiment, the biological packing material used is volcanic rock with a particle size of approximately 5-6 mm; the electrochemical packing material used is iron-carbon, composed of zero-valent iron and graphite carbon, with an iron-carbon particle size of approximately 4-5 mm and an iron content of approximately 77%. Therefore, in this embodiment, any biological packing layer is a volcanic rock layer; the electrochemical layer is an iron-carbon layer.

[0039] like Figure 1 As shown, the first reaction column 1 is filled from top to bottom with a first anoxic volcanic rock layer 101, an anoxic iron-carbon layer 102, and a second anoxic volcanic rock layer 103; a first working water level line L1 is set in the first reaction column 1, and the first working water level line L1 is higher than the top of the first anoxic volcanic rock layer 101. For example, in this embodiment, the distance between the first working water level and the bottom of the first reaction column 1 is 55cm.

[0040] like Figure 1 As shown, the second reaction column 2 is filled from top to bottom with an aerobic volcanic rock layer 201, an aerobic iron-carbon layer 202, and a third anoxic volcanic rock layer 203. An empty layer 204 is arranged below the third anoxic volcanic rock layer 203. A second working water level line L2 is set in the second reaction column 2. The second working water level line L2 is located between the top of the aerobic iron-carbon layer 202 and the top of the aerobic volcanic rock layer 201. For example, in this embodiment, the distance between the second working water level and the bottom of the second reaction column 2 is 60cm.

[0041] The wastewater treatment unit includes a treated water path 3 and a recycled water path 4. For example... Figure 1As shown, the treatment water path 3 sequentially connects to the first anoxic volcanic rock layer 101, the anoxic iron-carbon layer 102, the second anoxic volcanic rock layer 103, the aerobic volcanic rock layer 201, the aerobic iron-carbon layer 202, the third anoxic volcanic rock layer 203, and the empty layer 204. After sewage is input into the sewage treatment device, it will flow along the treatment water path 3, thereby reducing the total nitrogen and total phosphorus concentrations, and finally being discharged outside the device. One end of the reclaimed water path 4 is connected to the first reaction column 1 to input reclaimed liquid, i.e., nitrified liquid containing nitrates, into the first reaction column 1; the other end is connected to the return port 401 on the second reaction column 2. The return port 401 is opened between the second working water level line L2 and the top of the aerobic electrochemical packing layer, thereby receiving the nitrified liquid produced by the microbial reaction in the aerobic volcanic rock layer 201.

[0042] At the same time, such as Figure 1 As shown, an electrical connection is formed between the oxygen-deficient iron-carbon layer 102 and the aerobic iron-carbon layer 202. Exemplarily, a conductor 6 is used to complete the electrical connection between the two layers. This conductor 6 contains 48 oxygen-free pure copper wires with a cross-sectional area of ​​5.0 mm². 2 The exterior is wrapped with PVC insulation. 50cm of insulation is removed from both ends of the conductor 6, and then it is buried in the middle of each of the two sets of iron-carbon layers.

[0043] Preferably, such as Figure 1 As shown, the height of the return port 401 is higher than the height of the first working water level line L1. This allows the recycled liquid to flow into the first reaction column 1 by its own gravity through the recycled water passage 4, without the need to install pumps or other power equipment in the recycled water passage 4.

[0044] Preferably, in this embodiment, both the first reaction column 1 and the second reaction column 2 are cylindrical structures with the same cross-sectional diameter. In the first reaction column 1 and the second reaction column 2, by controlling the heights of the anoxic iron-carbon layer 102 and the aerobic iron-carbon layer 202, the volume ratio between them is made to 1:1.5. In this embodiment, for example, the total volume of the anoxic iron-carbon layer 102 is 2L, and the total volume of the aerobic iron-carbon layer 202 is 3L. More preferably, by controlling the heights of the first reaction column 1 and the second reaction column 2, the volume ratio between them is made to 1:2, thereby ensuring that the hydraulic retention time ratio of the wastewater in the first reaction column 1 and the second reaction column 2 is 1:2.

[0045] Preferably, such as Figure 1 As shown, a water distribution device 5 is arranged in the water treatment channel 3, and a water distribution drip filter is installed at the top of the second reaction column 2 to achieve the dispersed distribution of sewage when sewage is input into the second reaction column 2.

[0046] Example 2:

[0047] This embodiment provides a method for using the self-driven wastewater treatment device described in Example 1. The wastewater used is actual domestic sewage from a municipal wastewater treatment plant in Hangzhou, after the fine screen. The wastewater contains parameters such as COD and NH4. + The initial concentrations of -N, TN, and TP were 210.6±30.4 mg / L, 31.3±1.5 mg / L, 39.2±3.6 mg / L, and 5.9±1.3 mg / L, respectively, with a pH value of 7.0~8.0. During operation, the water temperature inside the wastewater treatment device was maintained between 13~25℃.

[0048] The usage method mainly includes the following steps:

[0049] S1. Activation steps:

[0050] During the operation of the wastewater treatment device, wastewater to be treated is continuously fed into the first reaction column 1.

[0051] First, keep the water return path 4 and the water flow path from the bottom of the first reaction column 1 closed until the liquid level in the first reaction column 1 reaches the first working water level line L1; then open the water path between the first reaction column 1 and the second reaction column 2 while keeping the water flow path from the bottom of the second reaction column 2 closed until the liquid level in the second reaction column 2 reaches the second working water level line L2; finally, open the water path at the bottom of the second reaction column 2.

[0052] S2. Loop steps:

[0053] Open the reclaimed water circuit 4 and control the flow rate in the reclaimed water circuit 4 to 75 ml / min via the valve. Simultaneously... Figure 1 As shown, the sewage is pumped to the top of the first reaction column 1 by the first water pump 301, with an input flow rate of 25 ml / min; then the sewage flowing out of the bottom of the first reaction column 1 is pumped to the top of the second reaction column 2 by the second water pump 302, with an input flow rate of 100 ml / min. During this process, sewage is introduced into the second reaction column 2 through a water distribution and drip filtration device; finally, the sewage that has been reacted is extracted from the second reaction column 2 by the third water pump 303 and discharged from the sewage treatment device, with an output flow rate of 25 ml / min.

[0054] During the above-mentioned operation, the carbon source carried by the sewage in the first reaction column 1, the ferrous ions generated by micro-electrolysis in the anoxic iron-carbon layer 102, and the electrons transported from the aerobic reaction zone via the wire can all become electron donors for denitrification by the microorganisms in the first anoxic volcanic rock layer 101 and the second anoxic volcanic rock layer 103. During this process, the microorganisms can convert nitrates in the sewage into nitrogen gas, thereby reducing the total nitrogen in the sewage. Then, in the second reaction column 2, the wastewater input through the water distribution and trickle filter device can be oxygenated on the aerobic volcanic rock layer 201 and undergo nitrification with the biofilm composed of microorganisms in this area, thereby converting ammonia nitrogen in the wastewater into nitrate. The nitrate-containing nitrate liquid is then returned to the first reaction column 1 through the reclaimed water channel 4 for heterotrophic denitrification. The subsequent aerobic iron-carbon layer 202 can fully utilize the dissolved oxygen in the wastewater to produce ferric ions, which will react with phosphate in the wastewater to form insoluble iron phosphate, thus removing phosphorus from the wastewater. Finally, in the third anoxic volcanic rock layer 203 formed below the second reaction column 2, the remaining nitrification liquid in the aerobic volcanic rock layer 201 can be received. Due to the lack of carbon source, the microorganisms in it mainly rely on this portion of nitrification liquid for autotrophic denitrification, thus removing an additional 1.5±0.4 mg / L of nitrate for the wastewater treatment device. Finally, the wastewater is discharged, and the overall hydraulic retention time in the wastewater treatment device is controlled at about 16 hours.

[0055] Wastewater treatment status monitoring:

[0056] In this example, under the operating method of Example 2, the concentration of pollutants at the inlet and outlet water is detected, and the current and voltage between the anoxic iron-carbon layer 102 and the aerobic iron-carbon layer 202 are measured. The pollutant concentration detection results are as follows: Figure 2 As shown in Table 1, the current and voltage detection results are as follows.

[0057] Depend on Figure 2 It can be seen that the wastewater treatment device can achieve long-term and stable removal of total nitrogen and total phosphorus in wastewater. During the monitoring period, the total nitrogen concentration at the bottom of the second reaction column 2 decreased to 10.4±2.2 mg / L and the total phosphorus concentration decreased to 0.2±0.1 mg / L, with removal efficiencies of 75.9±4.2% and 96.1±2.3%, respectively. Moreover, the trickling filter still exhibits high efficiency in removing various pollutants despite large temperature fluctuations and operating in a low-temperature environment.

[0058] Table 1 Voltage and Current Detection Results

[0059] project Current (mA) Voltage (V) Test results 0.85 0.468

[0060] As shown in Table 1, the current and voltage required for the reaction to form between the anoxic iron-carbon layer 102 and the aerobic iron-carbon layer 202 can be measured. This proves that under the structure of the wastewater treatment device in this invention, the excess electrons generated in the aerobic reaction zone are fully utilized to ensure the full progress of the bioelectrochemical reaction in the anoxic reaction zone, thereby eliminating the dependence on external power sources and reducing the overall power consumption of the wastewater treatment device.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-driven sewage treatment device, characterized in that, Comprising: a first reaction column (1) sequentially filled with a first anoxic biological filler layer, an anoxic electrochemical filler layer and a second anoxic biological filler layer from top to bottom, a first working water level line (L1) being arranged in the first reaction column (1), the first working water level line (L1) being higher than the top of the first anoxic biological filler layer; a second reaction column (2) sequentially filled with an aerobic biological filler layer, an aerobic electrochemical filler layer and a third anoxic biological filler layer from top to bottom, a second working water level line (L2) being arranged in the second reaction column (2), the second working water level line (L2) being arranged between the top of the aerobic electrochemical filler layer and the top of the aerobic biological filler layer; wherein a treatment water path (3) and a reuse water path (4) are arranged in the device; the treatment water path (3) sequentially communicates the first anoxic biological filler layer, the anoxic electrochemical filler layer, the second anoxic biological filler layer, the aerobic biological filler layer, the aerobic electrochemical filler layer and the third anoxic biological filler layer; one end of the reuse water path (4) is communicated with the first reaction column (1), and the other end is communicated with a backflow port (401) of the second reaction column (2), the backflow port (401) being arranged between the second working water level line (L2) and the top of the aerobic electrochemical filler layer; the anoxic electrochemical filler layer and the aerobic electrochemical filler layer are electrically connected.

2. A self-powered wastewater treatment device according to claim 1, wherein, The first anoxic biological filler layer, the second anoxic biological filler layer, the aerobic biological filler layer and the third anoxic biological filler layer are all composed of volcanic rock fillers.

3. A self-powered wastewater treatment device according to claim 2, wherein, The particle size of the volcanic rock fillers is 5-8 mm.

4. The self-powered wastewater treatment device of claim 1, wherein, The anoxic electrochemical filler layer and the aerobic electrochemical filler layer are both composed of iron-carbon fillers.

5. A self-powered wastewater treatment device according to claim 4, wherein, The particle size of the iron-carbon fillers is 3-5 mm; the iron content is 75±5%.

6. The self-powered wastewater treatment device of claim 1, wherein, The height position of the backflow port (401) is higher than the height position of the first working water level line (L1).

7. The self-powered wastewater treatment device of claim 1, wherein, The volume ratio of the anoxic electrochemical filler layer to the aerobic electrochemical filler layer is 1: (1.2-3).

8. The self-powered wastewater treatment device of claim 1, wherein, The hydraulic retention time ratio in the first reaction column (1) to that in the second reaction column (2) is 1: (2-5).

9. The self-powered wastewater treatment device of claim 1, wherein, A water distribution device (5) is arranged in the treatment water path (3) for inputting wastewater to be treated into the second reaction column (2).

10. A method of using a self-powered wastewater treatment device, comprising: A method for driving the self-driven sewage treatment device of any one of claims 1-9 comprises at least the following steps: S1. enabling step: continuously inputting wastewater to be treated into the first reaction column (1); first, keeping the reuse water path (4) and the water path outside the bottom of the first reaction column (1) closed until the liquid level in the first reaction column (1) reaches the first working water level line (L1); then, opening the water path between the first reaction column (1) and the second reaction column (2) and keeping the water path outside the bottom of the second reaction column (2) closed until the liquid level in the second reaction column (2) reaches the second working water level line (L2); finally, opening the water path at the bottom of the second reaction column (2); S2. Cycle step: continuously input wastewater into the first reaction column (1) while opening the reuse water path (4); during which the flow rate of wastewater input into the first reaction column (1) is 1-3Q, the flow rate of wastewater input into the second reaction column (2) is 4-8Q, the flow rate of reflux liquid in the reuse water path (4) is 3-9Q, the flow rate of liquid output from the second reaction column (2) after treatment is completed is 1-3Q, and the hydraulic retention time of waste liquid in the self-driven sewage treatment device is 10-16h.

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