Magnetic recovery sunlight Fenton reactor and method for treating mariculture wastewater

Abstract

The invention discloses a magnetic recovery sunlight Fenton reactor and method for treating mariculture wastewater, and belongs to the field of wastewater treatment. A first partition plate is fixed in the sunlight Fenton reaction tank body, a first water outflow channel is arranged between the lower end of the first partition plate and the lower end of the sunlight Fenton reaction tank body, a plurality of telescopic rods are fixedly arranged in the sunlight Fenton reaction tank body, magnets are fixed to the upper ends of the telescopic rods in a threaded screwing mode, and magnetic photocatalyst powder is distributed on the upper surfaces of the magnets; the sedimentation tank body and the sunlight Fenton reaction tank body share one tank wall, a partition plate II is fixed in the sedimentation tank body, a water outflow channel II is arranged between the partition plate II and the lower end of the sedimentation tank body, and the upper part of the sedimentation tank body is fixedly communicated with a water outlet pipe; the water inlet barrel is communicated with a water inlet pipe through a water inlet pump; the water inlet pipe is communicated with the upper part of the left side wall of the sunlight Fenton reaction tank body. The reactor disclosed by the invention is small in occupied area, strong in high-salt impact resistance, capable of efficiently removing pollutants, stable in operation, rapid in photocatalyst recovery, free from secondary pollution and relatively low in cost.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment, and particularly relates to a magnetic recovery solar Fenton reactor and method for treating seawater aquaculture wastewater. Background Art

[0002] In the mixed feeding mode of the seawater aquaculture industry, the addition of high-protein feed containing antibiotic drugs has exacerbated the pollution of coastal waters. Due to the persistence, high biological activity, and bioaccumulation of tetracycline antibiotics (TCs) residues in seawater aquaculture wastewater, it is urgent to develop efficient technical methods for the degradation and removal of TCs to reduce their adverse effects and protect the orderly development of the marine environment.

[0003] The photo-Fenton oxidation technology can generate reactive species such as free radicals with strong oxidation ability, and has remarkable removal efficiency for persistent and difficult-to-degrade TCs. Especially for a large amount of seawater aquaculture wastewater, using free, environmentally friendly, and sustainable solar energy resources to achieve photo-Fenton oxidation for the degradation of TCs in wastewater is a technical method with remarkable economic benefits. However, most photocatalysts have disadvantages such as difficult recycling and easy generation of secondary pollution, and the reactor has the limitation that sunlight is difficult to reach the deeper bottom of the pool, further increasing the difficulty of wastewater treatment and the process cost. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of existing reactors and photocatalysts in view of the characteristics of seawater aquaculture wastewater, and provide a magnetic recovery solar Fenton reactor and method for treating seawater aquaculture wastewater with rapid photocatalyst recovery, high salt tolerance, good absorption and utilization of sunlight, efficient pollutant removal, stable operation, and low cost.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A magnetic recovery solar Fenton reactor for treating seawater aquaculture wastewater, comprising an inlet water system, a solar Fenton reaction tank, and a sedimentation tank; the inlet water system includes an inlet water bucket, an inlet water pump, and an inlet water pipe; the solar Fenton reaction tank includes a solar Fenton reaction tank body, a first partition board, a plurality of telescopic rods, and a plurality of magnets; the sedimentation tank includes a sedimentation tank body, a second partition board, and an outlet water pipe;

[0007] A partition one is fixed inside the solar Fenton reaction tank body. There is a water outflow channel one between the lower end of the partition one and the lower end of the solar Fenton reaction tank body. The space between the partition one and the left side wall of the solar Fenton reaction tank body is the water inlet channel. A plurality of telescopic rods are arranged inside the solar Fenton reaction tank body. The lower ends of the plurality of telescopic rods are fixedly connected to the lower end of the solar Fenton reaction tank body. Magnetite is screwed and fixed at the upper ends of the plurality of telescopic rods. The magnetic photocatalyst powder is distributed on the upper surface of the magnetite; The sedimentation tank body is located on the right side of the solar Fenton reaction tank body and the two share a pool wall. A partition two is fixed inside the sedimentation tank body. There is a water outflow channel two between the partition two and the lower end of the sedimentation tank body. The space between the partition two and the shared pool wall is the water outlet channel. The upper part of the right side wall of the sedimentation tank body is fixedly communicated with one end of the water outlet pipe;

[0008] The water inlet bucket is communicated with one end of the water inlet pipe through a water inlet pump, and the other end of the water inlet pipe is fixedly communicated with the upper part of the left side wall of the solar Fenton reaction tank body.

[0009] Furthermore, the magnetite is a circular ferrite magnetite.

[0010] Furthermore, 20 - 40 g / L of magnetic photocatalyst powder is evenly distributed on the upper surface of the magnetite.

[0011] Furthermore, the height of the telescopic rod supporting the magnetite is 50 - 100 cm.

[0012] Furthermore, the diameter of the circular ferrite magnetite is 20 cm.

[0013] Furthermore, the immobilization method of the photocatalyst powder is magnetic recovery.

[0014] Furthermore, the photocatalyst is ZnFe2O4 photocatalyst or nano ZF / GCN composite photocatalyst.

[0015] Furthermore, the ZnFe2O4 photocatalyst is synthesized by a one - step microwave co - precipitation method, and the synthesis method is as follows:

[0016] First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water, and stir magnetically for 30 min; Then, add 4 mol / L of NaOH solution to adjust the pH of the solution to 10; Continue to heat and stir in a water - bath magnetic stirrer at 90 °C for 2 h, transfer to a microwave oven and heat at a power of 490 W for 25 - 30 min, then filter and wash with water successively until the pH of the supernatant is 7, and dry in a natural state; Calcinate in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst;

[0017] The nano-ZF / GCN composite photocatalyst is synthesized by means of secondary microwave co-precipitation, and the synthesis method is as follows:

[0018] First, weigh 100 g of ZnFe2O4 and 100 g of g-C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat them at a microwave power of 490 W for 25 - 30 min; then, heat them in a water bath with continuous stirring at 80 °C for 5 - 10 h to evaporate the solvent; subsequently, put the mixture into a crucible and calcine it in a muffle furnace at 500 °C for 150 min. After cooling to room temperature, rinse it with deionized water and ethanol, and dry it in a natural state to obtain the nano-ZF / GCN composite photocatalyst.

[0019] A magnetic recovery solar Fenton method for treating seawater aquaculture wastewater, the method is realized based on a reactor, and the method includes the following steps:

[0020] Step 1: Mix the seawater aquaculture wastewater contained in the inlet water bucket with the oxidant H2O2 solution evenly in advance, and then quickly pump it into the inlet pipe through the inlet water pump; then, flow through the inlet pipe into the inlet channel, and the water flows through the first outlet channel into the solar Fenton reaction tank body; the concentration of the H2O2 solution is 0.2 - 0.3 M;

[0021] Step 2: In the solar Fenton reaction tank body, under the irradiation of sunlight, the photocatalyst powder adsorbed on the magnet reacts fully with sunlight, captures pollutants, and then conducts solar Fenton oxidation degradation;

[0022] Step 3: The photocatalyst does not flow away with the water flow and cause secondary pollution. Subsequently, the wastewater enters the sedimentation tank through the outlet channel and the second outlet channel, and flows out through the outlet pipe after being mixed evenly.

[0023] Step 4: After the wastewater treatment is completed, take out the magnet, remove the photocatalyst powder, wash it with ethanol and ultrasonically clean it for 45 min for reuse.

[0024] Furthermore, the photocatalyst is a ZnFe2O4 photocatalyst or a nano-ZF / GCN composite photocatalyst. The ZnFe2O4 photocatalyst is synthesized by means of primary microwave co-precipitation, and the synthesis method is as follows:

[0025] First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water. Stir magnetically for 30 min. Then, add 4 mol / L NaOH solution to adjust the pH of the solution to 10. Continue heating and stirring in a water bath magnetic stirrer at 90 °C for 2 h, transfer to a microwave oven and heat at a power of 490 W for 25 - 30 min, then filter and wash with water successively until the pH of the supernatant is 7, and dry in the natural state. Calcinate in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst.

[0026] The nano ZF / GCN composite photocatalyst is synthesized by means of secondary microwave co - precipitation method, and the synthesis method is as follows:

[0027] First, weigh 100 g of ZnFe2O4 and 100 g of g - C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat at a microwave power of 490 W for 25 - 30 min. Then, heat in a continuously stirred water bath at 80 °C for 5 - 10 h to evaporate the solvent. Subsequently, put the mixture into a crucible, place it in a muffle furnace and calcinate at 500 °C for 150 min. After cooling to room temperature, rinse with deionized water and ethanol, and dry in the natural state to obtain the nano ZF / GCN composite photocatalyst.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. In view of the characteristics of seawater aquaculture wastewater, such as large volume, complex composition, many refractory substances, high salt content and closed aquaculture mode, the present invention designs a novel magnetic - recovery solar - light Fenton reactor, which utilizes free solar energy, and specific photocatalysts can achieve efficient treatment of pollutants by solar - light Fenton.

[0030] 2. The reactor of the present invention has a novel structure. In order to achieve better pollutant removal efficiency under continuous - flow conditions, two partitions are set up to fully mix and degrade the wastewater. An expansion rod is designed to support a disc - shaped magnet to adapt to the changes in solar light intensity under different weather and different time conditions, and it is beneficial to quickly take out the magnet to achieve the purpose of recovering the photocatalyst.

[0031] 3. The present invention immobilizes and magnetically recovers a novel nano - ferrite photocatalyst. This photocatalyst has characteristics such as high crystallinity, large specific surface area, small particle size, high magnetic strength, good absorption capacity for visible light and high separation efficiency of photo - generated carriers, and can achieve deep removal of refractory pollutants in seawater aquaculture wastewater. Utilizing the magnetism of ferrite in the photocatalyst, without adding external substances, the immobilization and magnetic recovery of the photocatalyst can be realized, and at the same time, the ferrite magnet has the ability to assist the photocatalytic efficiency.

[0032] 4. By means of the solar light Fenton technology, the present invention not only completely removes the refractory organic matters such as TC in the seawater aquaculture wastewater, but also realizes the advantages of nitrogen removal by the traditional biological method. The removal rate of TN remains above 90%, and the final content meets the first-class discharge standard of the "Discharge Requirements for Seawater Aquaculture Water" (SC / T 9103-2007). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a magnetic recovery solar light Fenton reactor for treating seawater aquaculture wastewater according to the present invention;

[0034] Figure 2 is a side view of the solar light Fenton reaction tank body.

[0035] The names of the components and the reference numerals involved in the above drawings are as follows:

[0036] 1. Water inlet bucket; 2. Water inlet pump; 3. Water inlet pipe; 4. First partition board; 5. Telescopic rod; 6. Magnet; 7. Second partition board; 8. Water outlet pipe. DETAILED DESCRIPTION OF THE INVENTION

[0037] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0038] DETAILED DESCRIPTION OF THE INVENTION I: As shown in Figure 1 and Figure 2 , this embodiment describes a magnetic recovery solar light Fenton reactor for treating seawater aquaculture wastewater, including an inlet water system, a solar light Fenton reaction tank, and a sedimentation tank; the inlet water system includes a water inlet bucket 1, a water inlet pump 2, and a water inlet pipe 3; the solar light Fenton reaction tank includes a solar light Fenton reaction tank body, a first partition board 4, a plurality of telescopic rods 5, and a plurality of magnets 6; the sedimentation tank includes a sedimentation tank body, a second partition board 7, and a water outlet pipe 8;

[0039] Inside the solar Fenton reaction tank body, a partition board 1-4 is fixed. There is a water outflow channel 1 (for water to enter) between the lower end of the partition board 1-4 and the lower end of the solar Fenton reaction tank body. The space between the partition board 1-4 and the left side wall of the solar Fenton reaction tank body is the water inlet channel. Inside the solar Fenton reaction tank body, a plurality of telescopic rods 5 are arranged. The lower ends of the plurality of telescopic rods 5 are fixedly connected to the lower end of the solar Fenton reaction tank body. At the upper ends of the plurality of telescopic rods 5, magnetic photocatalyst powders are threadedly tightened and fixed with magnets 6. The upper surface of the magnet 6 is distributed with magnetic photocatalyst powders (the photocatalyst powders have excellent salt tolerance, can achieve good absorption in the visible light band of sunlight, and are finally applied to the treatment of seawater aquaculture wastewater); the sedimentation tank body is located on the right side of the solar Fenton reaction tank body and the two share a pool wall. A partition board 2-7 is fixed inside the sedimentation tank body. There is a water outflow channel 2 (for water to flow out to the sedimentation tank) between the partition board 2-7 and the lower end of the sedimentation tank body. The space between the partition board 2-7 and the shared pool wall is the water outlet channel. The upper part of the right side wall of the sedimentation tank body is fixedly communicated with one end of the water outlet pipe 8;

[0040] The water inlet bucket 1 is communicated with one end of the water inlet pipe 3 through the water inlet pump 2. The other end of the water inlet pipe 3 is fixedly communicated with the upper part of the left side wall of the solar Fenton reaction tank body.

[0041] Specific Embodiment 2: As Figure 1 shown, this embodiment is a further description of Specific Embodiment 1. The magnet 6 is a disc-shaped ferrite magnet.

[0042] Specific Embodiment 3: As Figure 1 shown, this embodiment is a further description of Specific Embodiment 1. The upper surface of the magnet 6 is evenly distributed with 20-40 g / L of magnetic photocatalyst powder.

[0043] Specific Embodiment 4: As Figure 1 shown, this embodiment is a further description of Specific Embodiment 1. The height at which the telescopic rod 5 supports the magnet 6 is 50-100 cm (to adapt to the changes in solar light intensity under different weather and different time conditions).

[0044] Specific Embodiment 5: As Figure 1 shown, this embodiment is a further description of Specific Embodiment 2. The diameter of the disc-shaped ferrite magnet is 20 cm.

[0045] The disc-shaped magnet (with a diameter of 20 cm) with a certain height of support (50-100 cm) can solve the limitation that sunlight cannot reach the bottom of the pool. Under the irradiation of sunlight, the photocatalyst powder adsorbed on the disc-shaped magnet can effectively utilize sunlight, capture pollutants and then carry out solar Fenton oxidation and degradation.

[0046] Specific Embodiment Six: As Figure 1 shown, this embodiment is a further description of Specific Embodiment Two. The immobilization method of the photocatalyst powder is magnetic recovery (ferrite magnets will not cause changes in the performance of the photocatalyst, and the same composition can play a certain role in assisting the degradation of pollutants).

[0047] Specific Embodiment Seven: As Figure 1 shown, this embodiment is a further description of any one of Specific Embodiments One to Six. The photocatalyst is a ZnFe2O4 photocatalyst or a nano-ZF / GCN composite photocatalyst.

[0048] Specific Embodiment Eight: As Figure 1 shown, this embodiment is a further description of Specific Embodiment Seven. The ZnFe2O4 photocatalyst is synthesized by a one-step microwave co-precipitation method, and the synthesis method is as follows:

[0049] First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water, and stir magnetically for 30 min; then, add a 4 mol / L NaOH solution to adjust the pH of the solution to 10 (the addition amount of the NaOH solution needs to depend on the actual experimental operation, as long as the pH is adjusted to 10); continue to heat and stir in a water bath magnetic stirrer at 90 °C for 2 h, transfer to a microwave oven and heat at a power of 490 W for 25 - 30 min, then filter and wash with water successively until the pH of the supernatant is 7, and dry in a natural state; calcine in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst;

[0050] The nano-ZF / GCN composite photocatalyst is synthesized by a two-step microwave co-precipitation method, and the synthesis method is as follows:

[0051] First, weigh 100 g of ZnFe2O4 (synthesized by a one-step microwave co-precipitation method) and 100 g of g-C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat at a microwave power of 490 W for 25 - 30 min; then, heat in a water bath with continuous stirring at 80 °C for 5 - 10 h to evaporate the solvent; subsequently, put the mixture into a crucible and calcine in a muffle furnace at 500 °C for 150 min. After cooling to room temperature, wash with deionized water and ethanol, and dry in a natural state to obtain the nano-ZF / GCN composite photocatalyst.

[0052] In the present invention, the specific surface area of the nano-ZF / GCN composite photocatalyst powder is 33 m 2 / g, with a particle size between 10 and 20 nm, a magnetic strength of 35.25 emu / g, an absorption edge for visible light of approximately 600 nm, excellent photogenerated carrier separation efficiency, and a 100% removal rate for μg / L level TC as tested.

[0053] Embodiment Nine: As Figure 1 and Figure 2 shown, this embodiment describes a magnetic recovery solar Fenton method for treating seawater aquaculture wastewater, which is implemented based on the reactor described in any one of Embodiments Seven or Eight. The method includes the following steps:

[0054] Step 1: The seawater aquaculture wastewater contained in the inlet water bucket 1 is pre-mixed evenly with the oxidant H2O2 solution, and then quickly pumped into the inlet pipe 3 by the inlet water pump 2; and then flows into the first inlet channel through the inlet pipe 3, and the water flows into the solar Fenton reaction tank body through the first outlet channel; the concentration of the H2O2 solution is 0.2 - 0.3 M.

[0055] Step 2: In the solar Fenton reaction tank body, under the irradiation of sunlight, the photocatalyst powder adsorbed on the magnet 6 reacts fully with sunlight, captures the pollutants, and then undergoes solar Fenton oxidation degradation.

[0056] Step 3: The photocatalyst does not flow away with the water flow and cause secondary pollution. Then the wastewater enters the sedimentation tank through the outlet channel and the second outlet channel, and flows out through the outlet pipe 8 after being mixed evenly.

[0057] Step 4: After the wastewater treatment is completed, the magnet 6 is taken out, the photocatalyst powder is removed, and it is washed with ethanol and ultrasonically cleaned for 45 min for reuse.

[0058] Embodiment Ten: As Figure 1 shown, this embodiment is a further description of Embodiment Nine. The photocatalyst is a ZnFe2O4 photocatalyst or a nano-ZF / GCN composite photocatalyst. The ZnFe2O4 photocatalyst is synthesized by a one-step microwave co-precipitation method, and the synthesis method is as follows:

[0059] First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water, and stir magnetically for 30 min; then, add 4 mol / L NaOH solution to adjust the pH of the solution to 10 (the amount of NaOH solution added depends on the actual experimental operation, as long as the pH is adjusted to 10); continue to heat and stir in a water bath magnetic stirrer at 90 °C for 2 h, transfer to a microwave oven and heat at a power of 490 W for 25 - 30 min, then filter and wash with water successively until the pH of the supernatant is 7, and dry in the natural state; calcine in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst;

[0060] The nano-ZF / GCN composite photocatalyst is synthesized by means of secondary microwave co-precipitation, and the synthesis method is as follows:

[0061] First, weigh 100 g of ZnFe2O4 (synthesized by the primary microwave co-precipitation method) and 100 g of g-C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat at a microwave power of 490 W for 25 - 30 min; then, heat in a water bath with continuous stirring at 80 °C for 5 - 10 h to evaporate the solvent; subsequently, put the mixture into a crucible and calcine in a muffle furnace at 500 °C for 150 min. After cooling to room temperature, rinse with deionized water and ethanol, and dry in the natural state to obtain the nano-ZF / GCN composite photocatalyst.

[0062] Example 1:

[0063] In this example, when the photocatalyst powder is 28 g / L, H2O2 is 0.22 M, the pH of the fishpond of seawater aquaculture wastewater is 7.8, the hydraulic retention time is 2 h, the solar light intensity is 50 - 55 mW / cm 2 and the height of the telescopic rod is 70 - 75 cm, the photocatalyst has excellent salt tolerance, can efficiently utilize sunlight, realizes 100% removal of 8 μg / L of TC in the fishpond of seawater aquaculture wastewater, the removal rate of COD with a concentration of 180 mg / L can reach 91.24%, the removal rate of TN with a concentration of 1.52 mg / L can reach 94.73%, and the final content meets the first-class discharge standard of the "Discharge Requirements for Seawater Aquaculture Water" (SC / T 9103 - 2007).

[0064] Example 2:

[0065] In this example, when the photocatalyst powder is 33 g / L, H2O2 is 0.25 M, the pH of the shrimp pond of seawater aquaculture wastewater is 7.5, the hydraulic retention time is 2 h, the solar light intensity is 50 - 60 mW / cm 2When the height of the telescopic rod is 70-75 cm, the photocatalyst has excellent salt tolerance, can efficiently utilize sunlight, achieves 100% removal of 14 μg / L TC in the shrimp pond of seawater aquaculture wastewater, the removal rate of 215 mg / L COD can reach 90.96%, and the removal rate of 2.11 mg / L TN can reach 90.85%. The final content meets the first-class discharge standard of "Requirements for Seawater Aquaculture Water Discharge" (SC / T 9103-2007).

[0066] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other forms of devices without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent conditions of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claim.

[0067] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A magnetic recovery solar Fenton reactor for treating seawater aquaculture wastewater, characterized in that: It includes a water inlet system, a solar Fenton reaction tank, and a sedimentation tank; the water inlet system includes a water inlet bucket (1), a water inlet pump (2), and a water inlet pipe (3); the solar Fenton reaction tank includes a solar Fenton reaction tank body, a first partition (4), a plurality of telescopic rods (5), and a plurality of magnets (6); the sedimentation tank includes a sedimentation tank body, a second partition (7), and a water outlet pipe (8); A first partition (4) is fixed inside the solar Fenton reaction tank body. There is a first water outflow channel between the lower end of the first partition (4) and the lower end of the solar Fenton reaction tank body. The space between the first partition (4) and the left side wall of the solar Fenton reaction tank body is the water inlet channel. A plurality of telescopic rods (5) are arranged inside the solar Fenton reaction tank body. The lower ends of the plurality of telescopic rods (5) are fixedly connected to the lower end of the solar Fenton reaction tank body. Magnet (6) is screwed and fixed at the upper end of each of the plurality of telescopic rods (5). The upper surface of the magnet (6) is distributed with magnetic photocatalyst powder; the sedimentation tank body is located on the right side of the solar Fenton reaction tank body and the two share a pool wall. A second partition (7) is fixed inside the sedimentation tank body. There is a second water outflow channel between the second partition (7) and the lower end of the sedimentation tank body. The space between the second partition (7) and the shared pool wall is the water outlet channel. The upper part of the right side wall of the sedimentation tank body is fixedly communicated with one end of the water outlet pipe (8); The water inlet bucket (1) is communicated with one end of the water inlet pipe (3) through the water inlet pump (2), and the other end of the water inlet pipe (3) is fixedly communicated with the upper part of the left side wall of the solar Fenton reaction tank body.

2. The reactor according to claim 1, characterized in that: The magnet (6) is a disc-shaped ferrite magnet.

3. The reactor according to claim 1, characterized in that: The upper surface of the magnet (6) is evenly distributed with 20 - 40 g / L of magnetic photocatalyst powder.

4. The reactor according to claim 1, wherein: The height of the telescopic rod (5) supporting the magnet (6) is 50 - 100 cm.

5. The reactor according to claim 2, characterized in that: The diameter of the disc-shaped ferrite magnet is 20 cm.

6. The reactor according to claim 2, wherein: The immobilization method of the photocatalyst powder is magnetic recovery.

7. The reactor according to any one of claims 1-6, characterized in that: The photocatalyst is ZnFe2O4 photocatalyst or nano ZF / GCN composite photocatalyst.

8. The reactor according to claim 7, wherein: The ZnFe2O4 photocatalyst is synthesized by a one-step microwave co-precipitation method, and the synthesis method is as follows: First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water, and stir magnetically for 30 min; then, add 4 mol / L of NaOH solution to adjust the pH of the solution to 10; Continue to heat and stir in a water bath magnetic stirrer at 90 °C for 2 h, transfer to a microwave oven and heat at a power of 490 W for 25 - 30 min, then filter and wash with water in turn until the pH of the supernatant is 7, and dry in a natural state; calcine in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst; The nano ZF / GCN composite photocatalyst is synthesized by a two-step microwave co-precipitation method, and the synthesis method is as follows: First, weigh 100 g of ZnFe2O4 and 100 g of g-C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat them at a microwave power of 490 W for 25 - 30 min; then, heat them in a water bath with continuous stirring at 80 °C for 5 - 10 h to evaporate the solvent; subsequently, put the mixture into a crucible and calcine it in a muffle furnace at 500 °C for 150 min. After cooling to room temperature, rinse it with deionized water and ethanol, and dry it in a natural state to obtain the nano-ZF / GCN composite photocatalyst.

9. A magnetic recovery solar Fenton method for treating seawater aquaculture wastewater, characterized in that: The method is implemented based on the reactor described in Claim 7 or 8, and the method includes the following steps: Step 1: Premix the seawater aquaculture wastewater contained in the water inlet bucket (1) with the oxidant H2O2 solution evenly, and then quickly pump it into the water inlet pipe (3) through the water inlet pump (2); then, flow into the water inlet channel through the water inlet pipe (3), and the water flows through the first water outlet channel into the solar Fenton reaction tank body; the concentration of the H2O2 solution is 0.2 - 0.3 M. Step 2: In the solar Fenton reaction tank body, under the irradiation of sunlight, the photocatalyst powder adsorbed on the magnet (6) reacts fully with sunlight, captures the pollutants, and then conducts solar Fenton oxidation degradation. Step 3: The photocatalyst does not flow away with the water flow and cause secondary pollution. Subsequently, the wastewater enters the sedimentation tank through the water outlet channel and the second water outlet channel, and flows out through the water outlet pipe (8) after being mixed evenly. Step 4: After the wastewater treatment is completed, take out the magnet (6), remove the photocatalyst powder, wash it with ethanol and ultrasonically clean it for 45 min for reuse.

10. The magnetic recovery solar Fenton method according to claim 9, characterized in that: The photocatalyst is a ZnFe2O4 photocatalyst or a nano-ZF / GCN composite photocatalyst. The ZnFe2O4 photocatalyst is synthesized by a one-step microwave co-precipitation method, and the synthesis method is as follows: First, weigh 0.3 - 0.6 mol of Zn(NO3)2·3H2O and 0.6 - 1.2 mol of Fe(NO3)3·9H2O and dissolve them successively in 100 mL of deionized water, and stir magnetically for 30 min; then, add a 4 mol / L NaOH solution to adjust the pH of the solution to 10. Continue to heat and stir in a water bath magnetic stirrer at 90 °C for 2 h, transfer it to a microwave oven and heat it at a power of 490 W for 25 - 30 min, then filter and wash it with water successively until the pH of the supernatant is 7, and dry it in a natural state; calcine it in a muffle furnace at 500 °C for 150 min to obtain the ZnFe2O4 photocatalyst. The nano-ZF / GCN composite photocatalyst is synthesized by a two-step microwave co-precipitation method, and the synthesis method is as follows: First, weigh 100 g of ZnFe2O4 and 100 g of g-C3N4 and disperse them in 1000 mL of deionized water. After ultrasonic treatment for 1 h, heat them at a microwave power of 490 W for 25 - 30 min; then, heat them in a water bath with continuous stirring at 80 °C for 5 - 10 h to evaporate the solvent; subsequently, put the mixture into a crucible and calcine it in a muffle furnace at 500 °C for 150 min. After cooling to room temperature, rinse it with deionized water and ethanol, and dry it in a natural state to obtain the nano-ZF / GCN composite photocatalyst.

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