Micro-electrolysis biofilter system and method for rapidly purifying surface water

Abstract

The invention discloses a micro-electrolysis biological filter system and method for rapidly purifying surface water. The micro-electrolysis biological filter system comprises a porous filter plate, a modified porous reticular filler, a light filter material, an upper filter plate, an aeration device and a backwashing device. According to the micro-electrolysis biological filter, through the combination mode of the modified iron-based porous net-shaped filler and the light filter material, the starting time of a system can be effectively shortened, the removal efficiency and the treatment capacity of pollutants are improved, the occupied area and the construction cost of the system are reduced, and it can be guaranteed that effluent stably reaches the surface IV water or above. The COD removal rate of the biological filter is 60%-85%, the BOD removal rate of the biological filter is 75%-85%, the NH4 < + >-N removal rate of the biological filter is 70%-85%, the TP removal rate of the biological filter is 40%-70%, and the turbidity removal rate of the biological filter is increased by 80%-90%.

Description

Technical Field

[0001] The invention belongs to the technical field of surface water treatment, and in particular relates to a micro-electrolysis biofilter system and method for rapid purification of surface water. Background Art

[0002] Excessive discharge of domestic sewage and industrial wastewater has led to more inorganic and organic pollutants in surface water, and the chemical oxygen demand (COD), biochemical oxygen demand (BOD), total phosphorus (TP), and ammonia nitrogen content in the water body are high, which has an adverse impact on the water ecology and water environment quality, and also weakens the quality and availability of water resources. In order to improve the quality of the water ecological environment, ensure the quality of water sources and the sustainable development of water resources, it is necessary to purify surface water efficiently.

[0003] Traditional surface water purification methods often use physical and chemical methods such as coagulation, sedimentation, adsorption, and filtration. These methods have high treatment costs and carbon emissions, are difficult to operate and control during the treatment process, and have the risk of secondary pollution. For example, the addition of flocculants in the in-situ restoration of rivers is likely to cause secondary pollution of water bodies; the addition of microbial agents has low efficiency, requires repeated additions, and competes with indigenous microorganisms. In the ex-situ restoration of rivers, the use of coagulation, sedimentation, membrane filtration and other methods has high treatment costs and complex operations; the use of conventional aerated biological filters and other biofilm methods has problems such as long residence time, complex backwashing and high energy consumption, and inability to remove difficult-to-degrade substances.

[0004] Therefore, it is an urgent problem for technicians in this field to synergistically couple biological treatment technology with physicochemical treatment technology to provide a system and method for rapid purification of surface water with high purification efficiency, low cost and low energy consumption. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a micro-electrolysis biofilter system and method for rapid purification of surface water. The present invention can effectively reduce the startup time of the system, improve the removal efficiency and treatment capacity of pollutants, reduce the floor space and construction cost of the system, and ensure that the effluent can stably reach above IV surface water.

[0006] To achieve the above objectives, the present invention provides the following technical solutions: A micro-electrolysis biofilter system for rapid purification of surface water, comprising: A porous filter plate, which is arranged at the bottom of the micro-electrolysis biofilter and is used to support the modified porous mesh filler to prevent the filler from entering the water inlet area; A modified porous mesh filler, which is arranged on the porous filter plate at a height of 40% to 60% of the effective height of the filter tank, and is a porous mesh filler in which iron powder is fixed by polyvinyl alcohol and sodium alginate; Light filter material, which is one of polystyrene foam ball filter material, polypropylene plastic ball filter material or fiber ball filter material, and is located above the modified porous mesh filler at a height of 40%-60% of the effective height of the filter tank; An upper filter plate, the upper filter plate is located above the light filter material, a filter head outlet is arranged on the upper filter plate, and the pore size of the filter head is smaller than the size of the light filter material; An aeration device, the aeration device comprising an aerator located inside the modified porous mesh filler at a distance of 1 / 3 to 1 / 2 from the bottom, a flow meter and a variable frequency fan; The backwashing device comprises an aerator arranged inside the modified porous mesh filler at a distance of 1 / 3 to 1 / 2 from the bottom, and a rinse water distribution pipe located above the upper filter plate.

[0007] Preferably, the pore size of the porous filter plate is 0.8 cm-1.8 cm.

[0008] Preferably, the modified porous mesh filler is obtained by mixing sodium alginate and polyvinyl alcohol hydrogel with reduced iron powder and porous mesh filler, and then adding calcium chloride solution for cross-linking. The iron content of the modified porous mesh filler is 5%-35% and the size is 2cm-5cm.

[0009] More preferably, the porous mesh filler is one of a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler.

[0010] Preferably, the size of the lightweight filter material is 2 mm-10 mm.

[0011] The present invention also provides a method for using the micro-electrolysis biofilter system for rapid purification of surface water, comprising the following steps: After preliminary filtration or pretreatment, surface water enters the micro-electrolysis biofilter from the bottom. The hydraulic retention time of the micro-electrolysis biofilter is 25min-45min, and the volume load is 0.1kgCOD / (m 3 ·d)-0.3 kgCOD / (m 3 ·d), hydraulic load is 1m 3 / (m 2 ·h)-10 m 3 / (m 2 h), the aeration volume is set according to the air-water ratio of 0.8-3.0; In the micro-electrolysis biofilter, the surface water after preliminary filtration or pretreatment passes through the water distribution system and passes through the porous filter plate, modified porous mesh filler, lightweight filter material, and upper filter plate in sequence to complete purification; The effluent from the micro-electrolysis biofilter can be discharged directly or sent to a subsequent treatment device for further treatment.

[0012] Preferably, the preliminary filtration is that the surface water enters the raw water filtration storage tank and is filtered through a movable screen, and the screen aperture is 1mm-3mm; the pretreatment is that the surface water enters the front high-efficiency sedimentation tank, and flocculants are added in the front high-efficiency sedimentation tank for flocculation and sedimentation treatment.

[0013] Preferably, the subsequent treatment device includes a post-high-efficiency sedimentation tank, and the effluent from the micro-electrolysis biofilter enters the post-high-efficiency sedimentation tank, and a flocculant is added to the high-efficiency sedimentation tank for flocculation and sedimentation treatment. More preferably, the flocculant is one or both of PAC (polyaluminium chloride) and PAM (polyacrylamide).

[0014] Preferably, the micro-electrolysis biofilter is backwashed regularly with a cycle of 5 to 20 days, and the backwashing steps include air washing and water washing; in the air washing step: the aeration volume is set according to an air-water ratio of 15 to 25, and the water washing flow rate is set at 2 to 10 times the inlet water flow rate; in the water washing step: the backwashing water enters the filter tank through the upper part of the micro-electrolysis biofilter, and the backwashing wastewater enters the pre-high-efficiency sedimentation tank or the post-high-efficiency sedimentation tank.

[0015] The beneficial effects of the present invention are: The present invention greatly improves the speed of biofilm formation on the filler and the biomass of the biofilm by combining a modified porous mesh filler with a lightweight filter material, thereby effectively reducing the startup time of the system and improving the removal efficiency and treatment capacity of pollutants. At the same time, the modified porous mesh filler is loaded with reduced iron powder, achieving the simultaneous and efficient removal of organic matter, ammonia nitrogen, total phosphorus and turbidity in surface water, reducing the system's floor space and construction cost. The method provided by the present invention can ensure that the effluent can stably reach more than IV water on the surface.

[0016] The modified porous mesh filler of the present invention has a three-dimensional mesh structure, which can quickly achieve microbial biofilm formation by interception, attachment, etc. The formed biofilm structure is stable and can enhance the removal of ammonia nitrogen. After the porous mesh filler is modified, not only the roughness of the filler surface can be increased, the biofilm formation efficiency can be improved, but also the iron-based filler can improve the removal efficiency of difficult-to-degrade pollutants by micro-electrolysis, and the generated Fe 2+ and Fe 3+ Ions can remove a certain amount of TP through chemical phosphorus removal. The modified porous mesh filler has a specific gravity equivalent to that of water and can be suspended in water with high mass transfer efficiency.

[0017] The lightweight filter material layer of the present invention has a density less than that of water and can float below the upper filter plate to form a good filter layer, effectively reducing the turbidity of the effluent; the lightweight filter material layer can also achieve microbial biofilm formation by interception, attachment, etc., thereby improving the interception and degradation removal efficiency of pollutants.

[0018] The backwash water of the micro-electrolysis biofilter of the present invention is eluted into the filter tank from the upper part of the filter tank, so the backwashing energy consumption is low; and the lightweight filter material will automatically disperse when there is no water, so that the suspended matter blocked in the filter material is more easily removed by the backwashing water, so the backwashing efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the micro-electrolysis biofilter system of the present invention.

[0020] Figure numerals: 1-raw water filtration storage tank, 2-pre-high-efficiency sedimentation tank, 3-micro-electrolysis biological filter, 4-post-high-efficiency sedimentation tank, 5-water storage tank, 11-water intake pump, 12-movable screen, 301-water inlet pump, 302-check valve, 303-water distribution pipe / channel, 304-porous filter plate, 305-flow meter, 306-variable frequency fan, 307-aerator, 308-modified porous mesh filler, 309-light filter material, 310-upper filter plate, 311-filter head, 312-water outlet weir, 313-drainage electric valve, 314-backwash water pump, 315-rinsing water distribution pipe, 316-overflow port. DETAILED DESCRIPTION

[0021] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0022] Unless otherwise defined, technical or scientific terms used in the present disclosure shall have the common meanings understood by one of ordinary skill in the art to which the present invention belongs.

[0023] Figure 1 A schematic diagram of the micro-electrolysis biofilter system of the present invention.

[0024] like Figure 1 As shown, the micro-electrolysis biofilter system includes: a raw water filtration and storage tank 1, a front high-efficiency sedimentation tank 2, a micro-electrolysis biofilter 3, a rear high-efficiency sedimentation tank 4 and a water storage tank 5.

[0025] The raw water filtration storage tank 1 includes a water intake pump 11, which is arranged before the raw water filtration storage tank 1 and is used to pump surface water (such as river water, etc.) into the raw water filtration storage tank 1 for filtration through a movable screen 12. In one embodiment of the present invention, the aperture of the movable screen 12 is 1-3 mm. The raw water filtration storage tank is set with a high and low liquid level through a liquid level meter. When the liquid level is high, the water intake pump 11 stops, and when the liquid level is low, the water intake pump 11 starts.

[0026] The water filtered by the movable screen 12 further passes through the pre-high-efficiency sedimentation tank 2, and flocculants are added to the pre-high-efficiency sedimentation tank 2 for flocculation and sedimentation treatment.

[0027] The micro-electrolysis biofilter 3 includes: an inlet pump 301, a check valve 302, a water distribution pipe / channel 303, a porous filter plate 304, a flow meter 305, a variable frequency fan 306, an aerator 307, a modified porous mesh filler 308, a lightweight filter material 309, an upper filter plate 310, a filter head 311, an outlet weir 312, a drainage electric valve 313, a backwash water pump 314, a rinse water distribution pipe 315, and an overflow port 316.

[0028] like Figure 1 As shown, in the micro-electrolysis biofilter 3, the water inlet pump 301 is located before the check valve 302, the check valve 302 is connected to the water inlet pipe, and the water inlet pipe is connected to the water distribution pipe / channel 303. A porous filter plate 304 is arranged on the upper part. A modified porous mesh filler 308 is added above the porous filter plate 304. A light filter material 309 is located above the modified porous mesh filler 308. The upper filter plate 310 is located above the light filter material 309, and the water outlet size of the filter head 311 of the upper filter plate 310 is smaller than the size of the light filter material 309. The backwashing device includes an aerator 307 arranged inside the modified porous mesh filler 308 at 1 / 3-1 / 2 of the bottom, and a rinse water distribution pipe 315 located above the upper filter plate. The aerator 307 is connected to the flow meter 305 and the variable frequency fan 306 through the air pipe, and the aerator 307 is set at a position 1 / 3-1 / 2 of the modified porous mesh filler layer from the bottom. The elution water distribution pipe 315 is connected to the backwash water pump 314. The effluent of the effluent weir 312 is connected to the post-high efficiency sedimentation tank 4, and the overflow port 316 is connected to the raw water filtration storage tank 1. A drainage electric valve 313 is also set at the bottom of the micro-electrolysis biological filter 3.

[0029] In one embodiment of the present invention, the hydraulic retention time of the micro-electrolysis biofilter is 25-45 min, and the volume load is 0.1-0.3 kgCOD / (m 3 d), hydraulic load (filtration rate) is 1-10 m 3 / (m 2 ·h), the aeration volume is set according to the air-water ratio of 0.8-3.0.

[0030] In one embodiment of the present invention, the pore size of the porous filter plate 304 is 0.8-1.8 cm.

[0031] In one embodiment of the present invention, the height of the modified porous mesh filler 308 layer is 40%-60% of the effective height of the filter tank, and the dosage of the modified porous mesh filler 308 is 10-30% of the volume of the modified porous mesh filler layer.

[0032] In one embodiment of the present invention, the modified porous mesh filler 308 is prepared by the following method: 1) the porous mesh filler is ultrasonicated in ethanol for 1 hour to remove the oily substances on its surface; 2) SA-PVA (sodium alginate-polyvinyl alcohol) hydrogel is prepared: sodium alginate is dissolved at 50°C, polyvinyl alcohol is dissolved at 90°C, polyvinyl alcohol is cooled to 50°C, and mixed with the sodium alginate solution; 3) an appropriate amount of reduced iron powder is added to the mixed SA-PVA hydrogel, and mechanical stirring is performed to mix; 4) the porous mesh filler is placed in a centrifuge tube, the above solution is added, the speed of the mixer is 30 rpm, and the solution is released after running for 1 hour; 5) CaCl is added to the centrifuge tube 2 The solution is used as a cross-linking agent, and the mixture is run for 0.5 h at a speed of 50 rpm, and the liquid is released to obtain a modified porous mesh filler. The porous mesh filler can be a polyurethane sponge filler, a high-density polyethylene suspension carrier, or a polypropylene ball ring filler.

[0033] In one embodiment of the present invention, the size of the lightweight filter material 309 is 2-10 mm, the height of the lightweight filter material layer is 40%-60% of the effective height of the filter tank, and the lightweight filter material can be one of polystyrene foam ball filter material, polypropylene plastic ball filter material or fiber ball filter material.

[0034] In one embodiment of the present invention, the aeration device includes an aerator 307 located inside the modified porous mesh filler at 1 / 3-1 / 2 from the bottom, a flow meter 305 and a variable frequency fan 306, and the air supply is set at an air-water ratio of 0.8-3.0.

[0035] In one embodiment of the present invention, the specific operation steps of the backwashing device are as follows: ① air washing: turn off the water inlet pump 301, turn on the variable frequency fan 306, set the air supply volume according to the air-water ratio of 15-25, and maintain it for 45-75 s; turn off the variable frequency fan 306, open the drain electric valve 313 to drain, and drain 2 / 3-1 / 2 volume of water in the filter layer; ② water washing: turn on the backwash water pump 314, and turn off the backwash water pump 314 after the backwash water is added to the upper filter plate 310, repeat ①, and the flow rate of the backwash water pump 314 is set to 2-4 times the flow rate of the water inlet pump 301; ③ turn on the backwash water pump 314, and open the drain electric valve 313 to drain after the backwash water is added to the filter plate 310. When the water level drops to 1 / 2-1 / 3 volume of water in the filter layer, the drain electric valve 313 and the backwash water pump 314 are closed, and the backwashing is completed.

[0036] In one embodiment of the present invention, the post-high-efficiency sedimentation tank 4 can be added with PAC (polyaluminium chloride) and PAM (polyacrylamide) as needed, and the effluent of the post-high-efficiency sedimentation tank 4 enters the clean water storage tank 5 and then is discharged into the surface water body. If the clean water in the clean water storage tank 5 needs to be reused, such as road sprinkling, etc., a sodium hypochlorite disinfection tank can be added after the high-efficiency sedimentation tank 4.

[0037] In one embodiment of the present invention, the entire system is controlled by PLC to achieve automatic operation. Backwashing can be controlled by setting a pressure gauge to automatically backwash, or it can be automatically backwashed regularly. The period of regular backwashing is 5-20 days.

[0038] Experimental study on the treatment efficiency of surface water by the micro-electrolysis biofilter of the present invention: The modified porous mesh filler used in the following examples and comparative examples is a modified polyurethane sponge filler, the height of the modified porous mesh filler layer is 60% of the effective height of the filter tank, and the amount of the modified porous mesh filler added is 25% of the volume of the modified porous mesh filler layer. The size of the light filter material is 2-4 mm, the height of the light filter material layer is 40% of the effective height of the filter tank, and the light filter material is a polystyrene foam ball filter material.

[0039] Example 1

[0040] Surface water quality characteristics: COD Cr :60 mg / L,BOD 5 :10 mg / L,NH 4 + -N: 10.0 mg / L, TP: 1.0 mg / L, turbidity: 80 NTU.

[0041] Effluent quality of micro-electrolysis biofilter operated with combined fillers (retention time 40 min): COD Cr :10 mg / L,BOD 5 :2 mg / L,NH 4 + -N: 1.5 mg / L, TP: 0.3 mg / L, turbidity: 10 NTU.

[0042] Example 2

[0043] Surface water quality characteristics: COD Cr :40 mg / L,BOD 5 :6 mg / L,NH 4 + -N: 5.0 mg / L, TP: 0.4 mg / L, turbidity: 40 NTU.

[0044] Effluent quality of micro-electrolysis biofilter operated with combined fillers (retention time 40 min): COD Cr :8 mg / L,BOD 5 :1 mg / L,NH 4 + -N: 1.2 mg / L, TP: 0.2 mg / L, turbidity: 8 NTU.

[0045] Example 3

[0046] Surface water quality characteristics: COD Cr :20 mg / L,BOD 5 :4 mg / L,NH 4 + -N: 3.0 mg / L, TP: 0.3 mg / L, turbidity: 25 NTU.

[0047] Effluent quality of micro-electrolysis biofilter operated with combined fillers (retention time 40 min): COD Cr :5 mg / L,BOD 5 :1 mg / L,NH 4 + -N: 0.8 mg / L, TP: 0.18 mg / L, turbidity: 4 NTU.

[0048] Example 4

[0049] Surface water quality characteristics: COD Cr :10 mg / L,BOD 5 :2 mg / L,NH 4 + -N: 2.0 mg / L, TP: 0.2 mg / L, turbidity: 15 NTU.

[0050] Effluent quality of micro-electrolysis biofilter operated with combined fillers (retention time 40 min): COD Cr :4 mg / L,BOD 5 :0.5 mg / L,NH 4 + -N: 0.5 mg / L, TP: 0.12 mg / L, turbidity: 3 NTU.

[0051] It can be seen that the COD removal rate of the biofilter of the present invention is 60%-85%, the BOD removal rate is 75%-85%, and the NH 4 + -N removal rate is 70%-85%, TP removal rate is 40%-70%, and turbidity removal rate is 80%-90%.

[0052] Compared with conventional aerated biological filters (taking aerated biological filters using ceramsite as filler as an example), under the condition of the same pollutant removal efficiency, the residence time can be shortened by 5%-30%; under the condition of the same residence time, the COD removal rate can be increased by 5%-20%, and the NH 4 +-N removal rate can be increased by 10%-40%, TP removal rate by 10%-30%, turbidity removal rate by 5%-15%, and backwash energy consumption by 10%-20%.

[0053] Comparative Example 1 The micro-electrolysis biofilter system is basically the same as that of Example 1, except that no modified porous mesh filler is added. The effluent quality results are as follows (retention time is 40 min): COD Cr :25 mg / L,BOD 5 :4 mg / L,NH 4 + -N: 5.5mg / L, TP: 0.9 mg / L, turbidity: 10 NTU.

[0054] Comparative Example 2 The micro-electrolysis biofilter system is basically the same as that of Example 1, except that an unmodified porous mesh filler, i.e., a polyurethane sponge filler, is used. The effluent quality results are as follows (retention time is 40 min): COD Cr :12 mg / L,BOD 5 :2mg / L,NH 4 + -N: 1.5 mg / L, TP: 0.7 mg / L, turbidity: 10 NTU.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A micro-electrolysis biofilter system for rapid purification of surface water, characterized in that: include: A porous filter plate, which is arranged at the bottom of the micro-electrolysis biofilter and is used to support the modified porous mesh filler to prevent the filler from entering the water inlet area; A modified porous mesh filler, which is arranged on the porous filter plate at a height of 40% to 60% of the effective height of the filter tank, and is a porous mesh filler in which iron powder is fixed by polyvinyl alcohol and sodium alginate; Light filter material, which is one of polystyrene foam ball filter material, polypropylene plastic ball filter material or fiber ball filter material, and is located above the modified porous mesh filler at a height of 40%-60% of the effective height of the filter tank; An upper filter plate, the upper filter plate is located above the light filter material, a filter head outlet is arranged on the upper filter plate, and the pore size of the filter head is smaller than the size of the light filter material; An aeration device, the aeration device comprising an aerator located inside the modified porous mesh filler at a distance of 1 / 3 to 1 / 2 from the bottom, a flow meter and a variable frequency fan; The backwashing device comprises an aerator arranged inside the modified porous mesh filler at 1 / 3-1 / 2 of the bottom, a flow meter, a variable frequency fan, and a rinse water distribution pipe and a backwashing water pump located above the upper filter plate.

2. A micro-electrolysis biofilter system for rapid purification of surface water according to claim 1, characterized in that: The pore size of the porous filter plate is 0.8 cm-1.8 cm.

3. The micro-electrolysis biofilter system for rapid purification of surface water according to claim 1, characterized in that: The modified porous mesh filler is obtained by mixing sodium alginate and polyvinyl alcohol hydrogel with reduced iron powder and the porous mesh filler, and then adding calcium chloride solution for cross-linking. The iron content of the modified porous mesh filler is 5%-35% and the size is 2cm-5cm.

4. A micro-electrolysis biofilter system for rapid purification of surface water according to claim 3, characterized in that: The porous mesh filler is a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler.

5. The micro-electrolysis biofilter system for rapid purification of surface water according to claim 1, characterized in that: The size of the lightweight filter material is 2 mm-10 mm.

6. A method for using the micro-electrolysis biofilter system for rapid surface water purification according to any one of claims 1 to 5, characterized in that: The steps include: After preliminary filtration or pretreatment, surface water enters the micro-electrolysis biofilter from the bottom. In the micro-electrolysis biofilter, the surface water after preliminary filtration or pretreatment passes through the water distribution system and passes through the porous filter plate, modified porous mesh filler, lightweight filter material, and upper filter plate in sequence to complete purification; the effluent from the micro-electrolysis biofilter can be directly discharged or sent to subsequent treatment devices for further treatment.

7. The method for using a micro-electrolysis biofilter system for rapid surface water purification according to claim 6, characterized in that: The preliminary filtration is that the surface water enters the raw water filtration storage tank and is filtered through a movable screen with an aperture of 1mm-3mm. The pretreatment is that the surface water enters the pre-high-efficiency sedimentation tank, and flocculants are added to the high-efficiency sedimentation tank for flocculation and sedimentation treatment.

8. The method for using a micro-electrolysis biofilter system for rapid surface water purification according to claim 6, characterized in that: The hydraulic retention time of the micro-electrolysis biofilter is 25min-45min, and the volume load is 0.1kgCOD / (m 3 ·d)-0.3 kgCOD / (m 3 d), hydraulic load is 1m 3 / (m 2 ·h)-10 m 3 / (m 2 ·h), the aeration volume is set according to the air-water ratio of 0.8-3.

0.

9. The method for using a micro-electrolysis biofilter system for rapid surface water purification according to claim 6, characterized in that: The subsequent treatment device comprises a post-high efficiency sedimentation tank, and the effluent from the micro-electrolysis biological filter enters the post-high efficiency sedimentation tank, and a flocculant is added to the post-high efficiency sedimentation tank for flocculation and sedimentation treatment.

10. The method for using a micro-electrolysis biofilter system for rapid surface water purification according to claim 6, characterized in that: The micro-electrolysis biofilter is backwashed regularly with a cycle of 5 to 20 days. The backwashing steps include air washing and water washing. The aeration volume of the air washing is set according to the air-water ratio of 15-25, and the flow rate of the water washing is set at 2-10 times the inlet flow rate. The backwash wastewater enters the front high-efficiency sedimentation tank or the rear high-efficiency sedimentation tank.

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