Miniaturized domestic sewage treatment device

Abstract

The invention discloses a miniaturized domestic sewage treatment device. The domestic sewage treatment device comprises a first anode, a first cathode, a second anode, a second cathode, a stirring unit and a post-treatment unit which are sequentially arranged from upstream to downstream, magnesium sulfite particles are arranged at the first anode, activated aluminum oxide is arranged at the first cathode, the first cathode is communicated with an external air source, the second anode adopts an iron electrode plate, a copper-doped anti-perovskite phase coating is loaded on the surface of the second cathode, and the post-treatment unit mainly comprises a stainless steel electrode pair and calcium carbonate particles. The treatment device is small in size, convenient to operate, short in treatment period and low in requirement for water quality fluctuation.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a domestic sewage treatment device. Background Art

[0002] Domestic sewage refers to the sewage generated in residents' daily life, such as kitchen sewage, laundry sewage, bathroom sewage, and toilet sewage, etc. If this sewage is directly discharged into the environment without treatment, it will have a serious impact on the surrounding water bodies and the environment, threatening public health. Therefore, domestic sewage needs to be treated to ensure that it meets the discharge standards and is harmless to the environment.

[0003] Common treatment methods are carried out through the following steps: First is hydraulic balance adjustment: Since the discharge of domestic sewage is unstable, hydraulic balance adjustment is required before treatment to make the flow rate and water quality of the sewage stable, facilitating subsequent treatment. Then is pretreatment: There are a large number of suspended solids and impurities in domestic sewage, and pretreatment is required to remove large-particle impurities, such as sand, branches, stones, fabrics, etc., to avoid adverse effects on treatment equipment and subsequent processes. Next is biological treatment: Biological treatment is one of the current mainstream sewage treatment methods. Biological treatment uses microbial populations to degrade organic matter in sewage, converting it into carbon dioxide and water, and at the same time removing nutrients such as nitrogen and phosphorus in the sewage. Common biological treatment processes include the activated sludge method, MBR (Membrane Bioreactor), etc. Finally is advanced treatment: Advanced treatment refers to the deep purification of sewage to remove trace organic matter, microorganisms, viruses and other substances in it to ensure that the effluent quality meets the standards stably. Commonly used advanced treatment processes include precipitation, adsorption, oxidation, membrane separation, etc.

[0004] Among them, biological treatment is the key. By using the metabolic function of microorganisms, the organic pollutants in the sewage in a dissolved and colloidal state are converted into stable harmless substances. This process has relatively low operating costs. However, there are still problems such as long operation time, large floor area, large investment, long start-up time, and unstable treatment effect. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a miniaturized domestic sewage treatment device. The present invention treats domestic sewage by the method of electro-assisted catalytic oxidation, which not only has advantages such as small volume, convenient operation, and short treatment cycle, but also does not require continuous and regular addition of chemical agents. Only by controlling the voltage and current density can the release of corresponding ions be controlled.

[0006] The technical solution adopted by the present invention is as follows:

[0007] I. A miniaturized domestic sewage treatment device

[0008] The domestic sewage treatment device includes a first anode, a first cathode, a second anode, a second cathode, a stirring unit, and a post-treatment unit arranged in sequence from upstream to downstream; magnesium sulfite particles are arranged at the first anode, activated alumina is arranged at the first cathode, and the first cathode is communicated with an external air source. The second anode uses an iron electrode plate, and the surface of the second cathode is loaded with a copper-doped inverse perovskite phase coating. The post-treatment unit is mainly composed of a stainless steel electrode pair and calcium carbonate particles.

[0009] Preferably, the first anode, the first cathode, the second anode, and the second cathode all adopt sieve plate electrodes.

[0010] Preferably, the first anode, the first cathode, and the second cathode all adopt titanium electrode plates.

[0011] Preferably, a cavity is provided inside the first cathode, and a perforated pipe is arranged in the cavity. The perforated pipe is used to introduce an oxygen-containing gas (such as air) into the first cathode. One end of the perforated pipe is communicated with an external gas delivery device, and the other end extends into the cavity inside the first cathode. The first cathode and the perforated pipe are used to generate hydrogen peroxide by electrolyzing the oxygen-containing gas (such as air).

[0012] Preferably, the domestic sewage treatment device further includes a barrel body and a water collecting tank; water outlets and water inlets are respectively arranged at the upper and lower ends of the barrel body. The first anode, magnesium sulfite particles, the first cathode, activated alumina, the second anode, the second cathode, and the stirring unit are arranged in sequence from bottom to top inside. The magnesium sulfite particles are stacked on the upper surface of the first anode, and the activated alumina is stacked on the upper surface of the first cathode. The upper end of the water collecting tank is communicated with the water outlet, and a drain port is arranged at the lower end of the water collecting tank. The stainless steel electrode pair in the post-treatment unit is arranged at the bottom of the water collecting tank. The stainless steel electrode pair includes two relatively arranged stainless steel electrodes, and calcium carbonate particles are piled up around the stainless steel electrodes.

[0013] Preferably, the stirring unit includes a flared opening and a paddle; the large-diameter end of the flared opening is the inflow port, which is located at the lower end, and the small-diameter end is the outflow port, which is located at the upper end, and it is arranged below the water outlet; the paddle is located between the inflow port and the outflow port of the flared opening, and the top is connected to the stirring shaft, and the stirring shaft is in transmission connection with an external motor.

[0014] Preferably, the voltage between the first anode and the first cathode is 20 - 30V, and the distance is 10 - 15cm; the voltage between the second anode and the second cathode is 20 - 30V, and the distance is 10 - 15cm; in the stainless steel electrode pair, the voltage between the two stainless steel electrodes is 35V, and the distance is 5 - 10cm.

[0015] II. A domestic sewage treatment method using the above domestic sewage treatment device

[0016] The described domestic sewage treatment method comprises the following steps: allowing the domestic sewage to be treated to flow successively through a first anode, a first cathode, a second anode, and a second cathode, stirring through a stirring unit, and finally passing through a post-treatment unit to obtain the treated domestic sewage.

[0017] During the treatment process, nitrogen and phosphorus elements in the domestic sewage to be treated are converted into magnesium ammonium phosphate precipitate, and the remaining phosphorus element is converted into calcium phosphate precipitate. The magnesium ammonium phosphate precipitate and calcium phosphate precipitate are adsorbed by calcium carbonate particles in the post-treatment unit.

[0018] Specifically, during the treatment process, the acidic environment generated after the first anode is electrified dissolves magnesium sulfite particles, generating sulfite ions and magnesium ions; the perforated pipe introduces air to the first cathode, and after the first cathode is electrified, oxygen in the air is reduced to hydrogen peroxide. Oxygen and hydrogen peroxide can oxidize sulfite ions to generate sulfate radicals; after the second anode is electrified, ferrous ions are generated, and the ferrous ions can activate hydrogen peroxide to generate hydroxyl radicals; after the second cathode is electrified, nitrates in the domestic sewage to be treated are reduced to ammonia; oxygen, hydrogen peroxide, sulfate radicals, and hydroxyl radicals can oxidize polyphosphorus in the domestic sewage to be treated to generate orthophosphoric acid; the sulfate radicals and hydroxyl radicals can convert trace chloride ions in the domestic sewage to be treated into chlorine radicals under the catalytic action of activated alumina.

[0019] Specifically, during the treatment process, at the stirring unit, phosphate ions, magnesium ions, and ammonia react to form magnesium ammonium phosphate; in the post-treatment unit, the acidic environment generated after the stainless-steel electrode is electrified dissolves calcium carbonate particles, generating calcium ions, and the calcium ions can react with phosphate ions in the water to form calcium phosphate; the calcium carbonate particles can adsorb magnesium ammonium phosphate and calcium phosphate.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The treatment device of the present invention adopts the method of electro-assisted catalytic oxidation to treat domestic sewage, which is smaller in volume, more convenient to operate, shorter in treatment cycle, and has lower requirements for water quality fluctuations than the traditional biological treatment method;

[0022] 2. Different from general small-scale biological treatment devices, the device of the present invention does not need to be started in advance, can be turned off after use, does not need to maintain biological activity, and does not occupy land;

[0023] 3. The device of the present invention has small investment and is convenient to move, and is suitable for areas without centralized treatment facilities, especially for temporary use scenarios;

[0024] 4. Compared with common chemical oxidation methods, the device of the present invention does not require continuous addition of chemical agents at regular intervals and in fixed amounts. By controlling the voltage and current density, the release of corresponding ions can be controlled, and no manual operation is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a cross-sectional view of the small domestic sewage treatment device provided by the present invention;

[0026] Figure 2 is a left cross-sectional view (left) and a left view (right) of the small domestic sewage treatment device provided by the present invention;

[0027] Figure 3 is a right view (left) and a right cross-sectional view of the water collection tank (right) of the small domestic sewage treatment device provided by the present invention;

[0028] Figure 4 is a top view (without the bucket lid) of the small domestic sewage treatment device provided by the present invention;

[0029] Figure 5 is a flowchart of the small domestic sewage treatment method provided by the present invention.

[0030] In the figure: 1. Bucket body, 2. Water inlet, 3. Water outlet, 4. First anode, 5. First cathode, 6. Perforated pipe, 7. Magnesium sulfite particles, 8. Second anode, 9. Second cathode, 10. Blade, 11. Bell mouth, 12. Water collection tank, 13. Stainless steel electrode, 14. Calcium carbonate particles, 15. Drain outlet, 16. Activated alumina. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The first aspect of the present invention provides a domestic sewage treatment device. The domestic sewage treatment device of the present invention treats domestic sewage by an electro-assisted catalytic oxidation method. By controlling the voltage and current density, the release of corresponding ions can be controlled. It does not require continuous addition of chemical agents at regular intervals and in fixed amounts, is convenient to operate, and has a short treatment cycle.

[0033] As Figure 1 shown, the domestic sewage treatment device includes a first anode 4, a first cathode 5, a second anode 8, a second cathode 9, a stirring unit, and a post-treatment unit arranged in sequence from upstream to downstream. Magnesium sulfite particles 7 are arranged at the first anode 4. The first cathode 5 is communicated with an external air source. The second anode 8 is made of an iron electrode plate. The surface of the second cathode 9 is loaded with a copper (Cu)-doped inverse perovskite phase (Co 4 N) coating. The post-treatment unit is mainly composed of a pair of stainless steel electrodes and calcium carbonate particles 14.

[0034] Specifically, the first anode 4, the first cathode 5, the second anode 8, and the second cathode 9 all adopt sieve plate electrodes. In the present invention, the sieve plate electrode refers to an electrode plate with sieve holes. The domestic sewage to be treated passes through the sieve holes on the electrode plate and flows through the electrode.

[0035] Preferably, the first anode 4, the first cathode 5, and the second cathode 9 all adopt titanium electrode plates.

[0036] Specifically, after being energized, the first cathode 5 can electrolyze oxygen in the oxygen-containing gas (such as air) introduced from the outside into hydrogen peroxide.

[0037] Optionally, the implementation manner in which the first cathode 5 is connected to an external air source is as follows: A cavity is provided inside the first cathode 5, and a perforated pipe 6 is arranged in the cavity. The perforated pipe 6 is used to introduce air into the first cathode 5. One end of the perforated pipe 6 is connected to an external gas delivery device, and the other end extends into the cavity inside the first cathode 5. After being energized, the first cathode 5 can electrolyze oxygen in the gas introduced from the perforated pipe 6 into hydrogen peroxide.

[0038] In the above implementation manner, the perforated pipe 6 is preferably arranged parallel to the first cathode 5.

[0039] Preferably, the voltage between the first anode 4 and the first cathode 5 is 20 - 30V, and the distance is 10 - 15 cm; the voltage between the second anode 8 and the second cathode 9 is 20 - 30V, and the distance is 10 - 15 cm; in the stainless steel electrode pair, the voltage between the two stainless steel electrodes 13 is 35V, and the distance is 5 - 10 cm.

[0040] Furthermore, as Figure 4 shown, in the embodiment of the present invention, the domestic sewage treatment device further includes a barrel body 1 and a water collecting tank 12. The water collecting tank 12 is arranged on one side of the barrel body 1. As Figures 1 to 2 shown, a water outlet 3 and a water inlet 2 are respectively provided at the upper and lower ends of the barrel body 1. Inside, a first anode 4, magnesium sulfite particles 7 stacked on the upper surface of the first anode 4, a first cathode 5, activated alumina 16 stacked on the upper surface of the first cathode 5, a second anode 8, a second cathode 9, and a stirring unit are arranged in sequence from bottom to top. As Figure 3 shown, the upper end of the water collecting tank 12 is connected to the water outlet 3, and a drain port 15 is provided at the lower end. The stainless steel electrode pair in the post-treatment unit is arranged at the bottom of the tank. The stainless steel electrode pair includes two relatively arranged stainless steel electrodes 13, and calcium carbonate particles 14 are stacked around the stainless steel electrodes 13.

[0041] Furthermore, in the embodiment of the present invention, as Figure 1 and Figure 2As shown in the figure, the stirring unit includes a flared opening 11 and a paddle 10. The large-diameter end of the flared opening 11 is the inlet, which is located at the lower end; the small-diameter end is the outlet, which is located at the upper end and is arranged below the water outlet 3. The function of the flared opening 11 is to gather water flow, improve the stirring efficiency, and eliminate the need for a large propeller. The paddle 10 is located between the inlet and the outlet of the flared opening 11, and its top is connected to the stirring shaft, which is in transmission connection with an external motor.

[0042] The installation method of the stirring unit can be selected as follows: The stirring shaft is connected to the inner wall of the top of the barrel 1 through a bearing, and the large-diameter end of the flared opening 11 is connected to the inner wall of the barrel 1.

[0043] Specifically, the first anode 4 and the first cathode 5 are respectively electrically connected to the positive and negative electrodes of an external power source. The second anode 8 and the second cathode 9 are respectively electrically connected to the positive and negative electrodes of an external power source.

[0044] Specifically, in the embodiments of the present invention, the first anode 4, the first cathode 5, the second anode 8, and the second cathode 9 are all arranged horizontally and are arranged at intervals in sequence from bottom to top in the vertical direction. The first anode 4 is located above the water inlet 2, the second cathode 9 is located below the stirring unit, and the stirring unit is located below the water outlet 3. Magnesium sulfite particles 7 are stacked above the first anode 4, and activated alumina 16 is stacked above the first cathode 5. The first anode 4, the first cathode 5, the second anode 8, the second cathode 9, and the flared opening 11 are all connected to the inner side wall of the barrel 1.

[0045] In the embodiments of the present invention, the stainless steel electrode 13 is vertically arranged relative to the inner wall of the bottom of the water collection tank 12 and is connected to the inner wall of the bottom. Calcium carbonate particles 14 are stacked between the two stainless steel electrodes 13 and between each stainless steel electrode 13 and the inner side wall of the water collection tank 12.

[0046] Preferably, the stacking height of the calcium carbonate particles 14 is flush with the height of the stainless steel electrode 13.

[0047] In the embodiments of the present invention, the water inlet 2 and the water outlet 3 are respectively arranged on the opposite first side and second side of the barrel 1, the water collection tank 12 is arranged on the second side of the barrel 1, that is, on the side of the water outlet 3, and the drain port 15 is arranged on the second side of the water collection tank 12.

[0048] The second aspect of the present invention provides a domestic sewage treatment method using the above domestic sewage treatment device.

[0049] The domestic sewage treatment method provided by the present invention mainly includes the following steps: making the domestic sewage to be treated flow through the first anode 4, the first cathode 5, the second anode 8, and the second cathode 9 in sequence, stirring through the stirring unit, and finally passing through the post-treatment unit to obtain the treated domestic sewage. During the treatment process, the organic matter in the wastewater is completely oxidized. For example, polyphosphorus is completely oxidized into orthophosphoric acid. In addition, the nitrogen element is transformed from nitrate nitrogen to ammonia nitrogen and then becomes magnesium ammonium phosphate precipitate, and both nitrogen and phosphorus are removed. At the same time, the trace chloride ions present in the wastewater (such as the salts present in rural kitchen waste water and the chlorine originally contained in tap water entering the wastewater, etc.) are transformed into various chlorine free radicals (such as Cl·, Cl 2 ·- and ClO·, etc.), and these free radicals can accelerate the oxidation of organic matter.

[0050] In the embodiment of the present invention, the domestic sewage with solid residues removed is used as the domestic sewage to be treated. The domestic sewage to be treated flows into the barrel body 1 from the water inlet 2, passes through the first anode 4, the first cathode 5, the second anode 8, and the second cathode 9, and after being stirred by the paddle 10 at the bell mouth 11, flows into the water collecting tank 12 from the water outlet 3 of the barrel body 1. During this process, the nitrogen element and phosphorus element in the domestic sewage to be treated are transformed into magnesium ammonium phosphate precipitate. After the domestic sewage with magnesium ammonium phosphate precipitate flows into the water collecting tank 12, the residual phosphorus element in the domestic sewage is transformed into calcium phosphate precipitate, and both the magnesium ammonium phosphate precipitate and the calcium phosphate precipitate are adsorbed by the calcium carbonate particles 14. Finally, the treated domestic sewage is discharged from the drain outlet 15.

[0051] As Figure 5 shown, the specific implementation principle of the above process is as follows:

[0052] After the first anode 4 is electrified, an oxidation reaction occurs, generating H+ ions, resulting in a local decrease in the pH value around the first anode 4, forming an acidic environment. The generated acidic environment dissolves the magnesium sulfite particles 7, generating sulfite ions and magnesium ions;

[0053] Air is continuously introduced at the first cathode 5. After the first cathode 5 is electrified, the oxygen O 2 in the air is reduced to hydrogen peroxide H 2 O 2 , and both oxygen and hydrogen peroxide can oxidize sulfite ions to generate sulfate radicals;

[0054] The generated sulfate radicals and hydroxyl radicals, under the catalytic action of the activated alumina stacked on the surface of the first cathode 5, can transform the trace chloride ions present in the wastewater (such as the salts present in rural kitchen waste water and the chlorine originally contained in tap water entering the wastewater, etc.) into various chlorine free radicals (such as Cl·, Cl 2 ·- and ClO·, etc.), and these free radicals can accelerate the oxidation of organic matter.

[0055] After the second anode 8 is energized, ferrous ions are generated. The ferrous ions can activate hydrogen peroxide to generate more hydroxyl radicals. After the second cathode 9 is energized, nitrate in the domestic sewage to be treated is reduced to ammonia.

[0056] Oxygen, hydrogen peroxide, sulfate radicals, and hydroxyl radicals can oxidize the organic matter and polyphosphorus in the domestic sewage to be treated to generate orthophosphoric acid. At the same time, hydroxyl radicals also have a bactericidal effect.

[0057] At the stirring unit, through the convergence of the bell mouth 11 and the stirring of the paddle 10, phosphate ions, magnesium ions, ammonia, etc. in the water react to form magnesium ammonium phosphate solid particles.

[0058] In the post-treatment unit, the acidic environment generated after the stainless steel electrode 13 is energized dissolves the particles 14, and the generated calcium ions can react with the remaining phosphate ions in the water that have not been precipitated to form calcium phosphate solid particles. The calcium carbonate particles 14 can adsorb the magnesium ammonium phosphate solid particles and calcium phosphate solid particles in the water, thereby removing phosphorus and nitrogen elements in the domestic sewage.

[0059] Based on the ideal embodiments of the present invention as an inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A miniaturized domestic sewage treatment device, characterized in that: The domestic sewage treatment device comprises a first anode (4), a first cathode (5), a second anode (8), a second cathode (9), a stirring unit and a post-treatment unit which are arranged in sequence from upstream to downstream; magnesium sulfite particles (7) are arranged at the first anode (4), activated alumina (16) is arranged at the first cathode (5), and the first cathode (5) is connected to an external air source; the second anode (8) adopts an iron electrode plate, and the surface of the second cathode (9) is loaded with a copper-doped antiperovskite phase coating; the post-treatment unit is mainly composed of a stainless steel electrode pair and calcium carbonate particles (14).

2. The miniaturized domestic sewage treatment device according to claim 1 is characterized in that: The first anode (4), the first cathode (5), the second anode (8) and the second cathode (9) all use sieve plate electrodes; the first anode (4), the first cathode (5) and the second cathode (9) all use titanium electrode plates.

3. The miniaturized domestic sewage treatment device according to claim 1 is characterized in that: A cavity is provided inside the first cathode (5), and a perforated tube (6) is provided in the cavity. The perforated tube (6) is used to introduce oxygen-containing gas into the first cathode (5). One end of the perforated tube (6) is connected to an external gas delivery device, and the other end extends into the cavity inside the first cathode (5). The first cathode (5) and the perforated tube (6) are used to generate hydrogen peroxide by electrolyzing the oxygen-containing gas.

4. The miniaturized domestic sewage treatment device according to claim 1 is characterized in that: The domestic sewage treatment device further comprises a barrel body (1) and a water collection tank (12); the upper and lower ends of the barrel body (1) are respectively provided with a water outlet (3) and a water inlet (2); a first anode (4), magnesium sulfite particles (7), a first cathode (5), activated alumina (16), a second anode (8), a second cathode (9) and a stirring unit are arranged in sequence from bottom to top inside; the magnesium sulfite particles (7) are stacked on the upper surface of the first anode (4), and the activated alumina (16) is stacked on the upper surface of the first cathode (5); the upper end of the water collection tank (12) is connected to the water outlet (3), and the lower end of the water collection tank (12) is provided with a drain outlet (15); a stainless steel electrode pair in the post-treatment unit is arranged at the bottom of the water collection tank (12), the stainless steel electrode pair comprises two stainless steel electrodes (13) arranged opposite to each other, and calcium carbonate particles (14) are stacked around the stainless steel electrodes (13).

5. The miniaturized domestic sewage treatment device according to claim 4 is characterized in that: The stirring unit comprises a bell mouth (11) and a paddle (10); the large diameter end of the bell mouth (11) is an inlet located at the lower end, and the small diameter end is an outlet located at the upper end and arranged below the water outlet (3); the paddle (10) is located between the inlet and the outlet of the bell mouth (11), and the top end is connected to a stirring shaft, and the stirring shaft is connected to an external motor transmission.

6. The miniaturized domestic sewage treatment device according to claim 1 is characterized in that: The voltage between the first anode (4) and the first cathode (5) is 20 to 30 V, and the distance between them is 10 to 15 cm; the voltage between the second anode (8) and the second cathode (9) is 20 to 30 V, and the distance between them is 10 to 15 cm; and in the stainless steel electrode pair, the voltage between the two stainless steel electrodes (13) is 35 V, and the distance between them is 5 to 10 cm.

7. A method for treating domestic sewage using the domestic sewage treatment device according to any one of claims 1 to 6, characterized in that: The following steps are involved: The domestic sewage to be treated is made to flow through a first anode (4), a first cathode (5), a second anode (8), and a second cathode (9) in sequence, and is stirred by a stirring unit, and finally passes through a post-treatment unit to obtain treated domestic sewage.

8. The method for treating domestic sewage according to claim 7, characterized in that: During the treatment process, nitrogen and phosphorus in the domestic sewage to be treated are converted into ammonium magnesium phosphate precipitates, and the remaining phosphorus is converted into calcium phosphate precipitates. The ammonium magnesium phosphate precipitates and the calcium phosphate precipitates are adsorbed by calcium carbonate particles (14) in the post-treatment unit.

9. The method for treating domestic sewage according to claim 7, characterized in that: The acidic environment generated by the first anode (4) after being energized dissolves the magnesium sulfite particles (7) to generate sulfite and magnesium ions; the perforated pipe (6) introduces air to the first cathode (5); the first cathode (5) reduces oxygen in the air to hydrogen peroxide after being energized; oxygen and hydrogen peroxide can oxidize sulfite to generate sulfate free radicals; the second anode (8) generates ferrous ions after being energized; ferrous ions can activate hydrogen peroxide to generate hydroxyl free radicals; the second cathode (9) reduces nitrates in the domestic sewage to be treated to ammonia after being energized; the oxygen, hydrogen peroxide, sulfate free radicals and hydroxyl free radicals can oxidize polyphosphorus in the domestic sewage to be treated to generate orthophosphoric acid; the sulfate free radicals and hydroxyl free radicals can convert trace chloride ions in the domestic sewage to be treated into chloride free radicals under the catalytic action of the activated alumina (16).

10. The method for treating domestic sewage according to claim 9, characterized in that: In the stirring unit, phosphate radicals, magnesium ions and ammonia react to generate ammonium magnesium phosphate; in the post-processing unit, the acidic environment generated by the stainless steel electrode (13) after being energized dissolves the calcium carbonate particles (14) to generate calcium ions, which can react with phosphate radicals in water to generate calcium phosphate; the calcium carbonate particles (14) can adsorb ammonium magnesium phosphate and calcium phosphate.

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