A method for purifying aquaculture wastewater

Abstract

The application discloses a breeding sewage recycling purification method. The application first uses a water collecting well and a grid to filter large particles and suspended substances such as livestock and poultry hair, excrement and the like, and the filtered sewage flows into an adsorption system, then flows into a disinfection tank and a neutralization tank, and after staying for a period of time, flows into an artificial wetland, and finally is transported into a livestock and poultry farm, wherein the adsorption system is a sandwich type purification system formed by a sponge, self-made biochar and self-made molecular sieve, and the disinfection tank uses a bactericide compounded by a modified quaternary ammonium salt and a banana peel. The breeding sewage recycling purification method in the application has high purification degree of breeding sewage, and various indexes are far lower than the national first emission standard, the purified water can be used in the breeding farm again, secondary recycling of the sewage is realized, and the breeding is linked with planting and landscape viewing, so that higher economic benefits are brought.

Description

Technical Field

[0001] This invention relates to the field of aquaculture wastewater treatment technology, specifically a method for circulating and purifying aquaculture wastewater. Background Technology

[0002] Against the backdrop of widespread encouragement for expanded livestock and poultry farming in rural areas, my country's livestock and poultry farming industry has flourished, exhibiting a trend towards industrialization, large-scale operation, and regionalization in recent years. During the livestock and poultry farming process, factors such as sanitation and cleaning of farms and livestock, as well as natural excretion by animals, generate large amounts of wastewater. If this wastewater is not effectively treated, it will inevitably pollute and damage the surrounding ecological environment, especially the water environment. Furthermore, accidental ingestion of such wastewater by humans and animals can have significant adverse effects on their health. Therefore, it is necessary to strengthen the scientific treatment of livestock and poultry farming wastewater.

[0003] Traditional livestock and poultry farming is production-driven, and pollution control technologies mostly refer only to post-production treatment. The main methods include physical methods, such as sedimentation, dehydration, and drying of livestock and poultry farming pollution; chemical methods, such as coagulation, oxidation, and disinfection of livestock and poultry farming pollution; biological methods, such as anaerobic, aerobic, and facultative anaerobic treatment of livestock and poultry farming pollution; ecological methods, such as oxidation ponds, wetlands, and ecological ditches for treating livestock and poultry farming pollution; and resource utilization, such as composting, organic fertilizer, and feed processing of livestock and poultry farming pollution.

[0004] Traditional livestock and poultry wastewater treatment methods still suffer from low efficiency and high cost in treating nitrogen and phosphorus. The existing technology's treatment costs are in stark contrast to the low profits and high risks of livestock farming. Furthermore, operational and management issues, particularly those related to operator error, often lead to malfunctions in existing facilities. Therefore, developing a livestock wastewater treatment method that requires minimal investment, boasts high purification efficiency, low energy consumption, low operating and management costs, and is easy to operate is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for circulating and purifying aquaculture wastewater to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for circulating and purifying aquaculture wastewater, characterized by mainly including the following steps:

[0007] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0008] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0009] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 30 to 40 minutes, the disinfected wastewater is obtained.

[0010] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 10 to 20 minutes to obtain neutralized wastewater;

[0011] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0012] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0013] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0014] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0015] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 10-12 minutes. After cooling to room temperature, grind it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0016] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar and 20% ammonium sulfide solution, 0.1 times the mass of the watermelon rind and potassium ferrate powder, and add 50 times the mass of the watermelon rind biochar and high-purity water in 8-9 portions, stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 6-7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 20-30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0017] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 5-6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0018] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A from step c at 1 times its mass of mixture A, stir evenly to form mixture C.

[0019] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 7 to 8 times to obtain a filter cake.

[0020] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0021] g. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate in step f at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0022] h. Mix the modified watermelon rind biochar from step b and the modified molecular sieve from step g at a volume ratio of 5:1 to prepare an adsorbent.

[0023] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0024] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 6-7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature rises to 30-50°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25-30 min. Heat to 70-90°C and react for 7-9 h. Stop heating to obtain the reaction solution.

[0025] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85°C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution. Stir for 7-8 minutes to obtain a mixture. Then place the mixture in a refrigerator and cool at 2-3°C for 6 hours to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 3-4 times. Dry at room temperature for 12 hours to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0026] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 70-80℃ to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 5-6 portions. Continue heating and maintain the temperature at 70-80℃ for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40℃ to obtain the modified quaternary ammonium salt crude product. Wash and filter 9-10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50℃ for 10 hours to obtain the modified quaternary ammonium salt.

[0027] D. Soak banana peels in 30°C warm water (20 times their weight) for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 3-4 hours to obtain banana peel extract.

[0028] E. Mix the modified quaternary ammonium salt from step C and the banana peel extract from step D at a mass ratio of 1:2 to prepare a bactericide.

[0029] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0030] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a hydraulic slope of 5%, and a sewage retention time of 24-72h; the bottom of the wetland is covered with 10-20cm of 10mm gravel, followed by 10-20cm of 5mm coarse sand, and finally 20-40cm of loose clay-loam.

[0031] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0033] This invention employs a grid, an adsorption filtration pond, sterilization treatment, and artificial wetland to purify aquaculture wastewater to obtain solid fertilizer and purified water, thereby achieving the effects of secondary wastewater recycling and the linkage between aquaculture, planting, and tourism.

[0034] First, the adsorption filtration pool is a sandwich-style purification system consisting of a sponge, homemade biochar, and a homemade molecular sieve. The homemade biochar is prepared from ammonium sulfide, potassium ferrate, and watermelon rind. Potassium ferrate decomposes into potassium hydroxide after dissolving in water. During activation, the carbon groups of the watermelon rind biochar react with potassium hydroxide to form carbonates, promoting pore formation and creating a porous structure that improves adsorption. Ammonium sulfide decomposes with the cellulose of watermelon rind at high temperatures, introducing sulfur and amino groups, which can complex with heavy metal ions, improving the adsorption capacity of the modified watermelon rind biochar. The homemade molecular sieve is a zirconium sulfate-modified molecular sieve that undergoes an ion exchange reaction, replacing sodium ions with zirconium ions and grafting them onto the surface of the molecular sieve. This process accumulates on the surface of the molecular sieve, forming new micropores, increasing the micropore volume, enlarging the pore size of the molecular sieve, and enhancing the adsorption capacity of the homemade molecular sieve.

[0035] Secondly, a self-made bactericide is used in the sterilization process. This self-made bactericide is a bactericide formed by compounding modified quaternary ammonium salt and banana peel. The modified quaternary ammonium salt is prepared by combining long-chain alkyl dimethyl tertiary ammonium salt and metronidazole. The carbon atom in metronidazole, which is attached to the chlorine atom, attacks the nitrogen atom in the quaternary ammonium salt, resulting in nucleophilic substitution. This introduces the metronidazole molecule into the quaternary ammonium salt molecule, making the modified quaternary ammonium salt molecule contain two positively charged quaternary nitrogen ions, which are beneficial for adsorption on the bacterial surface. At the same time, the modified quaternary ammonium salt has two hydrophobic groups, namely the long-chain alkyl group and metronidazole, which can penetrate into the lipid layer of bacterial cells, leading to enzyme inactivation. The combined effect of the two enhances the bactericidal activity of the modified quaternary ammonium salt. In addition, banana peel contains banana peel extract, which can inhibit the growth of bacteria and fungi. It works synergistically with the modified quaternary ammonium salt to improve the effect of killing bacteria and viruses.

[0036] Finally, the aquaculture wastewater is filtered through a screen and collection well to trap sludge, which is then fermented on-site into fertilizer. The filtered wastewater flows into an adsorption filtration tank. Unlike traditional multi-stage adsorption, this integrated filtration tank removes nitrogen, phosphorus, and heavy metals simultaneously. After sterilization and disinfection, the wastewater is discharged into an artificial wetland composed of calamus, canna lily, algae, water hyacinth, goldfish algae, and calla lily. This combination of plants, which has both aesthetic appeal and high purification efficiency, enables the reuse of wastewater and facilitates multi-faceted economic cooperation in planting, aquaculture, and tourism. In addition, the introduction of the adsorption filtration tank can effectively alleviate the saturation of the artificial wetland, reduce siltation, and extend its service life. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. In the following embodiments, the test methods for each index of the aquaculture wastewater recycling treatment method are as follows:

[0039] The water quality indicators involved in this invention, such as chemical oxygen demand, total phosphorus, ammonia nitrogen, and total nitrogen, are all tested and analyzed in accordance with the "Methods for Analysis and Testing of Water and Wastewater".

[0040] Sterilization rate: Samples were taken from the inlet and outlet of the circulation system, diluted, and spread on beef extract peptone medium and agar medium. The samples were incubated at 24℃ for 24 hours and the results were observed to calculate the sterilization rate.

[0041] Example 1

[0042] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0043] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0044] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0045] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0046] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain neutralized wastewater;

[0047] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0048] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0049] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0050] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0051] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0052] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar, 20% ammonium sulfide solution, and 0.1 times the mass of the watermelon rind, potassium ferrate powder. Add 50 times the mass of the watermelon rind biochar, high-purity water, in 8 portions, while stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0053] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0054] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A in step c at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0055] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0056] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0057] g. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate in step f at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0058] h. Mix the modified watermelon rind biochar from step b and the modified molecular sieve from step g at a volume ratio of 5:1 to prepare an adsorbent.

[0059] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0060] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0061] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0062] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 80°C to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 6 portions. Continue heating and maintain the temperature at 80°C for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40°C to obtain the modified quaternary ammonium salt crude product. Wash and filter 10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50°C for 10 hours to obtain the modified quaternary ammonium salt.

[0063] D. Soak banana peels in 30°C warm water at 20 times their weight for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of banana peels of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 4 hours to obtain banana peel extract.

[0064] E. Mix the modified quaternary ammonium salt from step C and the banana peel extract from step D at a mass ratio of 1:2 to prepare a bactericide.

[0065] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0066] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a watershed slope of 5%, and a sewage retention time of 48h; the bottom of the wetland is covered with 15cm of 10mm gravel, followed by 15cm of 5mm coarse sand, and finally 35cm of loose clay-loam.

[0067] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0068] Example 2

[0069] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0070] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0071] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0072] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0073] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain purified water.

[0074] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0075] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0076] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0077] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0078] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar, 20% ammonium sulfide solution, and 0.1 times the mass of the watermelon rind, potassium ferrate powder. Add 50 times the mass of the watermelon rind biochar, high-purity water, in 8 portions, while stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0079] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0080] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A in step c at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0081] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0082] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0083] g. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate in step f at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0084] h. Mix the modified watermelon rind biochar from step b and the modified molecular sieve from step g at a volume ratio of 5:1 to prepare an adsorbent.

[0085] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0086] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0087] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0088] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 80°C to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 6 portions. Continue heating and maintain the temperature at 80°C for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40°C to obtain the modified quaternary ammonium salt crude product. Wash and filter 10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50°C for 10 hours to obtain the modified quaternary ammonium salt.

[0089] D. Soak banana peels in 30°C warm water at 20 times their weight for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of banana peels of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 4 hours to obtain banana peel extract.

[0090] E. Mix the modified quaternary ammonium salt from step C and the banana peel extract from step D at a mass ratio of 1:2 to prepare a bactericide.

[0091] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0092] Example 3

[0093] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0094] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0095] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0096] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0097] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain neutralized wastewater;

[0098] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0099] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0100] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0101] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0102] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0103] b. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0104] c. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A from step b at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0105] d. Place the stirring magnetic rod and the mixture C from step c into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner. React at 80°C for 24 hours to obtain a reaction solution. Then cool to room temperature, remove the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0106] e. Place the filter cake from step d in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0107] f. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate from step e at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0108] g. Mix the watermelon rind biochar from step a and the modified molecular sieve from step f at a volume ratio of 5:1 to prepare an adsorbent.

[0109] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0110] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0111] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0112] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 80°C to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 6 portions. Continue heating and maintain the temperature at 80°C for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40°C to obtain the modified quaternary ammonium salt crude product. Wash and filter 10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50°C for 10 hours to obtain the modified quaternary ammonium salt.

[0113] D. Soak banana peels in 30°C warm water at 20 times their weight for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of banana peels of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 4 hours to obtain banana peel extract.

[0114] E. Mix the modified quaternary ammonium salt from step C and the banana peel extract from step D at a mass ratio of 1:2 to prepare a bactericide.

[0115] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0116] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a watershed slope of 5%, and a sewage retention time of 48h; the bottom of the wetland is covered with 15cm of 10mm gravel, followed by 15cm of 5mm coarse sand, and finally 35cm of loose clay-loam.

[0117] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0118] Example 4

[0119] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0120] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0121] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0122] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0123] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain neutralized wastewater;

[0124] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0125] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0126] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0127] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0128] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0129] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar, 20% ammonium sulfide solution, and 0.1 times the mass of the watermelon rind, potassium ferrate powder. Add 50 times the mass of the watermelon rind biochar, high-purity water, in 8 portions, while stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0130] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0131] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A in step c at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0132] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0133] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0134] g. Mix the modified watermelon rind biochar from step b and the molecular sieve from step f at a volume ratio of 5:1 to prepare an adsorbent.

[0135] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0136] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0137] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0138] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 80°C to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 6 portions. Continue heating and maintain the temperature at 80°C for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40°C to obtain the modified quaternary ammonium salt crude product. Wash and filter 10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50°C for 10 hours to obtain the modified quaternary ammonium salt.

[0139] D. Soak banana peels in 30°C warm water at 20 times their weight for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of banana peels of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 4 hours to obtain banana peel extract.

[0140] E. Mix the modified quaternary ammonium salt from step C and the banana peel extract from step D at a mass ratio of 1:2 to prepare a bactericide.

[0141] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0142] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a watershed slope of 5%, and a sewage retention time of 48h; the bottom of the wetland is covered with 15cm of 10mm gravel, followed by 15cm of 5mm coarse sand, and finally 35cm of loose clay-loam.

[0143] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0144] Example 5

[0145] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0146] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0147] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0148] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0149] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain neutralized wastewater;

[0150] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0151] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0152] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0153] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0154] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0155] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar, 20% ammonium sulfide solution, and 0.1 times the mass of the watermelon rind, potassium ferrate powder. Add 50 times the mass of the watermelon rind biochar, high-purity water, in 8 portions, while stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0156] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0157] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A in step c at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0158] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0159] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0160] g. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate in step f at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0161] h. Mix the modified watermelon rind from step b and the modified molecular sieve from step g at a volume ratio of 5:1 to prepare an adsorbent.

[0162] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0163] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0164] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0165] C. Soak banana peels in 30°C warm water (20 times their weight) for 1 hour, boil for 2 hours, and filter through 16 layers of gauze to obtain residue and filtrate A. Add 10 times their weight of water to the residue and boil for 1 hour. Filter through 16 layers of gauze to obtain filtrate B. Mix filtrate A and filtrate B and concentrate at 60°C for 4 hours to obtain banana peel extract.

[0166] D. Mix the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B and the banana peel extract from step C at a mass ratio of 1:2 to prepare a bactericide.

[0167] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0168] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a watershed slope of 5%, and a sewage retention time of 48h; the bottom of the wetland is covered with 15cm of 10mm gravel, followed by 15cm of 5mm coarse sand, and finally 35cm of loose clay-loam.

[0169] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0170] Example 6

[0171] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0172] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0173] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0174] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0175] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain neutralized wastewater;

[0176] (5) After the neutralized wastewater flows into the artificial wetland, it is then transported to the aquaculture farm.

[0177] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0178] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0179] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0180] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0181] b. Place the watermelon rind biochar from step a in a beaker, add 4 times the mass of the watermelon rind biochar, 20% ammonium sulfide solution, and 0.1 times the mass of the watermelon rind, potassium ferrate powder. Add 50 times the mass of the watermelon rind biochar, high-purity water, in 8 portions, while stirring with a glass rod for 30 minutes to obtain a mixed solution. Then, stir the mixed solution at 150 r / min for 7 hours at 80℃. Place the mixed solution in a 105℃ oven and dry for 30 minutes. Grind it with an agate mortar and pass it through a 100-mesh sieve to obtain powder. Finally, place the powder in a muffle furnace and pyrolyze it at 600℃ for 1 hour. After natural cooling, remove it and pass it through a 100-mesh sieve again to obtain modified watermelon rind biochar.

[0182] c. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0183] d. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A in step c at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0184] e. Place the stirring magnetic rod and the mixture C from step d together into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and react at 80°C for 24 hours to obtain a reaction solution. Then cool it to room temperature, take out the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0185] f. Place the filter cake from step e in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0186] g. Dissolve zirconium sulfate in 25 times its mass of deionized water to obtain a zirconium sulfate solution. Impregnate the molecular sieve and zirconium sulfate in step f at a volume ratio of 1:1 for 24 hours to obtain a mixed solution. Place the mixed solution in an oven and dry at 120°C for 12 hours. Then calcine it in a muffle furnace at 500°C for 3 hours to obtain the modified molecular sieve.

[0187] h. Mix the modified watermelon rind biochar from step b and the modified molecular sieve from step g at a volume ratio of 5:1 to prepare an adsorbent.

[0188] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0189] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0190] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0191] C. Place the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt from step B in a three-necked flask, add acetonitrile at 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, heat to 80°C to obtain a mixed solution, then weigh metronidazole at 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt and add it to the mixed solution in 6 portions. Continue heating and maintain the temperature at 80°C for 12 hours. After the reaction is completed, stop heating to obtain a reaction solution. After the reaction solution cools to room temperature, distill at 0.09 MPa and 40°C to obtain the modified quaternary ammonium salt crude product. Wash and filter 10 times with 30% acetone at 10 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt, and dry at 50°C for 10 hours to obtain the modified quaternary ammonium salt.

[0192] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0193] Furthermore, the artificial wetland described in step (5) has a size of 40m×12m×0.8m, a watershed slope of 5%, and a sewage retention time of 48h; the bottom of the wetland is covered with 15cm of 10mm gravel, followed by 15cm of 5mm coarse sand, and finally 35cm of loose clay-loam.

[0194] Furthermore, the plants in the artificial wetland described in step (5) consist of calamus, canna lily, kelp, water hyacinth, goldfish algae, and calla lily.

[0195] Comparative Example

[0196] A method for recycling and purifying aquaculture wastewater mainly includes the following steps:

[0197] (1) After the aquaculture wastewater passes through the artificial screen, it enters the collection well and is pumped to the inclined screen. After filtration, the filtered wastewater is obtained.

[0198] (2) The filtered wastewater flows into the adsorption system by gravity, and after adsorption in the adsorption system, the adsorbed wastewater is obtained;

[0199] (3) The adsorption-treated wastewater flows into a disinfection tank containing bactericide by gravity, and after standing for 40 minutes, the disinfected wastewater is obtained.

[0200] (4) The disinfection wastewater flows into a neutralization tank containing a neutralizing agent by gravity and is left to stand for 20 minutes to obtain purified water.

[0201] Furthermore, the grid in step (1) is made of SS304 material with a grid gap of 5mm; the size of the water collection well is 4.0m×1.5m×3.0m, and the residence time is 40min.

[0202] Furthermore, the adsorption system described in step (2) is a plastic bucket with a height of 1.5m and an inner diameter of 1.2m. A 20cm sponge is laid at the bottom of the bucket, and a 10cm adsorbent is placed on top, followed by another 10cm sponge. This process is repeated twice to form a sandwich-style artificial purification system.

[0203] Furthermore, the preparation method of the adsorbent contained in the adsorption system described in step (2) mainly includes the following steps:

[0204] a. After washing the watermelon rind with distilled water, place it in an oven and dry it at 105℃ for 12 minutes. After cooling to room temperature, crush it with an agate mortar and pass it through a 100-mesh sieve to obtain watermelon rind biochar.

[0205] b. Add 5.06 times the mass of deionized water to sodium hydroxide. After the beaker cools, add 0.13 times the mass of sodium aluminate while stirring with a glass rod. Stir continuously with a glass rod for 6 minutes. After the solution becomes clear, add 2.34 times the mass of silica sol and stir evenly to make a mixture. Seal the mouth of the beaker containing the mixture with plastic wrap and place it on a heat-collecting constant temperature magnetic stirrer. Stir continuously at room temperature at a speed of 150 r / min for 1 hour. Then raise the temperature to 60℃ and stir at the same speed for 4 hours to obtain mixture A.

[0206] c. Dissolve aluminum sulfate in deionized water at 7.89 times its mass, then add 0.44 times its mass of aluminum sulfate to obtain silica, thus preparing mixture B. Add mixture B to mixture A from step b at 1 times its mass of mixture B, and stir evenly to form mixture C.

[0207] d. Place the stirring magnetic rod and the mixture C from step c into the drying oven of a stainless steel high-pressure reactor with a polytetrafluoroethylene liner. React at 80°C for 24 hours to obtain a reaction solution. Then cool to room temperature, remove the reaction solution, and use a vacuum filter to wash and filter the reaction solution with twice the volume of distilled water. Repeat this process 8 times to obtain a filter cake.

[0208] e. Place the filter cake from step d in a constant temperature drying oven and dry it at 100℃ for 12 hours to obtain a solid. Then grind the solid with an agate mortar and pass it through a 100-mesh sieve to obtain a molecular sieve.

[0209] f. Mix the watermelon rind biochar from step a and the molecular sieve from step e at a volume ratio of 5:1 to prepare an adsorbent.

[0210] Furthermore, the preparation method of the bactericide in step (3) mainly includes the following steps:

[0211] A. Mix long-chain alkyl dimethyl tertiary amine and isopropanol (1 times the mass of long-chain alkyl dimethyl tertiary amine) evenly in a beaker and place in a three-necked flask. Stir at 250 r / min for 7 min at room temperature. Then add hydrochloric acid (7.8% by mass) (0.14 times the mass of long-chain alkyl dimethyl tertiary amine) and continue stirring at the same speed until the temperature reaches 30°C. Then add cyclochloropropane (0.36 times the mass of long-chain alkyl dimethyl tertiary amine) and stir at the same speed for 25 min. Heat to 80°C and react for 7 h. Stop heating to obtain the reaction solution.

[0212] B. Pour the reaction solution from step A into a rotary evaporator and obtain a pale yellow paste-like crude product at 0.09 MPa and 85 °C. Cool to room temperature and pour in 50 times the mass of the reaction solution of 30% acetone solution and stir for 8 min to obtain a mixture. Then place the mixture in a refrigerator and cool at 2 °C for 6 h to obtain a white precipitate. Dissolve the precipitate by filtration with 3 times the mass of the reaction solution of distilled water. Repeat the operation 4 times and dry at room temperature for 12 h to obtain a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt.

[0213] Furthermore, the neutralizing agent in step (4) is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 phosphate buffer solution in a volume ratio of 1:1.

[0214] Example of effect

[0215] Table 1 below shows the performance analysis results of the aquaculture wastewater recycling and purification methods of Examples 1 to 6 and the comparative examples of the present invention.

[0216] Table 1

[0217]

[0218] A comparison of the experimental data from Example 1 and the comparative example reveals that the purified water from Example 1 exhibits lower concentrations of chemical oxygen demand (COD), total nitrogen (TNO), total phosphorus (TP), and ammonia nitrogen, along with a better sterilization rate. This indicates that the adsorbent can undergo complexation reactions with nitrogen and phosphorus. Furthermore, its porous structure gives the adsorbent a highly efficient adsorption capacity. Simultaneously, the bactericide possesses hydrophobic groups and positively charged ions, allowing it to penetrate deep into bacterial cells and inactivate them. The addition of banana peel extract further enhances the bactericidal effect. Moreover, the introduction of constructed wetlands allows the soil layer and vegetation to further adsorb nitrogen, phosphorus, and COD from the wastewater, resulting in improved purification of the water. All indicators are below the national Class I emission standard, and the purified water can be recycled back to the aquaculture farm. A comparison of experimental data from Examples 1 and 2 reveals that the concentrations of chemical oxygen demand (COD), total nitrogen, total phosphorus, and ammonia nitrogen in Example 2 are higher, indicating that the soil layer filler in the constructed wetland can adsorb the remaining nitrogen and phosphorus, reducing the concentration of pollutants. The vegetation effectively adsorbs COD through the degradation by microorganisms attached to the substrate and plant roots. A comparison of experimental data from Examples 1 and 3 shows that the total phosphorus concentration in Example 3 is higher, indicating that without modification of the watermelon rind biochar, only a single... The microporous structure and small pore size result in weak phosphorus adsorption capacity. Furthermore, the absence of sulfur and amino groups prevents phosphorus complexation, further weakening the adsorption capacity of the watermelon rind biochar. A comparison of experimental data from Examples 1 and 4 reveals that Example 4 has higher total nitrogen and ammonia nitrogen concentrations, indicating that without modification of the molecular sieve, the pore structure cannot be adjusted, leading to smaller pore sizes and fewer micropores. Additionally, the lack of zirconium ions prevents the molecular sieve from reacting with nitrogen, further weakening its nitrogen adsorption capacity. A comparison of experimental data from Examples 1 and 5 shows that Example 5 has a lower sterilization rate. This indicates that without modification of the quaternary ammonium salt, the quaternary ammonium salt does not contain positively charged quaternary nitrogen ions and cannot be adsorbed onto the bacterial surface. Furthermore, the quaternary ammonium salt has only one hydrophobic group, preventing it from penetrating deeper into the bacterial cells and thus failing to destroy the cells. This results in a high bacterial concentration and a low sterilization rate in the wastewater. A comparison of the experimental data from Examples 1 and 6 reveals that the sterilization rate in Example 6 is lower, indicating that banana peel extract can effectively inhibit the growth of bacteria and fungi. If only modified quaternary ammonium salt is used, it cannot synergize with the banana peel, resulting in a less efficient sterilization effect and a higher bacterial concentration in the wastewater.

[0219] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for purifying and recycling aquaculture wastewater, characterized by, The method mainly comprises the following steps: (1) the aquaculture wastewater is filtered through a manual grid and then is pumped into a slanting screen through a collecting well, and the filtered wastewater is obtained after being filtered through the screen; (2) the filtered wastewater is self-flowed into an adsorption system, and the adsorption-treated wastewater is obtained after being adsorbed through the adsorption system containing an adsorbent; The preparation method of the adsorbent is as follows: a. the watermelon peel is cleaned with distilled water, is dried in an oven at 105 DEG C for 10-12 min, is cooled to room temperature, is crushed with a jade mortar and is sieved through a 100-mesh screen to prepare the watermelon peel biochar; b. the watermelon peel biochar is placed in a beaker, 4 times the mass of the watermelon peel biochar of 20% ammonium sulfide solution, 0.1 times the mass of the watermelon peel of potassium ferrite powder and 50 times the mass of the watermelon peel biochar of high-purity water are added in 8-9 times, the mixture is stirred with a glass rod for 30 min, the mixture is stirred at 150 r / min for 6-7 h at 80 DEG C, the mixture is dried in an oven at 105 DEG C for 20-30 min, the powder is crushed with a jade mortar and sieved through a 100-mesh screen, the powder is pyrolyzed in a muffle furnace at 600 DEG C for 1 h, the modified watermelon peel biochar is obtained after being naturally cooled and sieved through a 100-mesh screen again; c. 5.06 times the mass of sodium hydroxide in deionized water is added to the sodium hydroxide, the beaker is cooled, 0.13 times the mass of sodium metaaluminate in the sodium hydroxide is added under the condition of stirring with a glass rod, the solution is continuously stirred for 5-6 min, 2.34 times the mass of the sodium hydroxide in silica sol is added after the solution is transparent, the mixture is stirred uniformly, the beaker is sealed with a plastic wrap, the mixture is continuously stirred at room temperature for 1 h at 150 r / min, the temperature is increased to 60 DEG C, and the mixture is stirred for 4 h at the same speed to prepare the mixture A; d. the aluminum sulfate is dissolved in 7.89 times the mass of the aluminum sulfate in deionized water, 0.44 times the mass of the aluminum sulfate in white carbon black is added to the mixture to prepare the mixture B, the mixture B is added to 1 times the mass of the mixture B in the mixture A, and the mixture C is formed after being stirred uniformly; e. the stirring magnet and the mixture C are placed in a dry box of a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, the reaction is carried out at 80 DEG C for 24 h to prepare the reaction liquid, the reaction liquid is cooled to room temperature, the reaction liquid is taken out, the reaction liquid is washed and filtered with 2 times the volume of the reaction liquid in distilled water, and the process is repeated for 7-8 times to obtain the filter cake; f. the filter cake is placed in a constant-temperature drying box and is dried at 100 DEG C for 12 h to obtain a solid, the solid is crushed with a jade mortar and sieved through a 100-mesh screen to prepare the molecular sieve; g. the zirconium sulfate is dissolved in 25 times the mass of the zirconium sulfate in deionized water to prepare a zirconium sulfate solution, the molecular sieve and the zirconium sulfate are impregnated at a volume ratio of 1:1 for 24 h to prepare the mixture, the mixture is dried in an oven at 120 DEG C for 12 h, and is calcined in a muffle furnace at 500 DEG C for 3 h to obtain the modified molecular sieve; h. the modified watermelon peel biochar and the modified molecular sieve are mixed uniformly at a volume ratio of 5:1 to prepare the adsorbent. (3) The adsorbed sewage is self-flowed into a disinfection tank containing a bactericide, and after standing for 30-40 min, the sewage is obtained; the bactericide is prepared by the following method: A. The long-chain alkyl dimethyl tertiary amine, isopropyl alcohol with a mass fraction of 1 times that of the long-chain alkyl dimethyl tertiary amine are mixed uniformly in a beaker and then placed in a three-necked flask, stirred at a speed of 250 r / min for 6-7 min at room temperature, then 0.14 times the mass of the long-chain alkyl dimethyl tertiary amine of hydrochloric acid with a mass fraction of 7.8% is added, and the stirring is continued at the same speed until the temperature is raised to 30-50 DEG C, then 0.36 times the mass of the long-chain alkyl dimethyl tertiary amine of cyclochloropropane is added, and the stirring is continued at the same speed for 25-30 min, and then the temperature is raised to 70-90 DEG C, and the reaction is carried out for 7-9 h, and then the heating is stopped, and a reaction solution is prepared; B. The reaction solution in step A is poured into a rotary evaporation flask, and a light yellow paste-like crude product is obtained at 0.09 MPa and 85 DEG C, and then the temperature is cooled to room temperature, and the crude product is poured into a solution of acetone with a mass fraction of 30% and a mass of 50 times that of the reaction solution, and stirred for 7-8 min, and then a mixed solution is prepared, and then the mixed solution is placed in a refrigerator, and cooled at 2-3 DEG C for 6 h, and then a white precipitate is obtained, and then the precipitate is redissolved by using distilled water with a mass of 3 times that of the reaction solution, and the operation is repeated for 3-4 times, and then the precipitate is dried at room temperature for 12 h, and then a long-chain alkyl dimethyl tertiary amine quaternary ammonium salt is prepared; C. The long-chain alkyl dimethyl tertiary amine quaternary ammonium salt is placed in a three-necked flask, and then 0.16 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt of acetonitrile is added, and then the temperature is raised to 70-80 DEG C, and a mixed solution is prepared, and then 0.79 times the mass of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt of metronidazole is added to the mixed solution in 5-6 times, and then the temperature is continuously raised, and the reaction is carried out at 70-80 DEG C for 12 h, and then the heating is stopped after the reaction is completed, and a reaction solution is prepared, and then the reaction solution is cooled to room temperature, and then the reaction solution is distilled at 0.09 MPa and 40 DEG C, and a crude modified quaternary ammonium salt is obtained, and then the crude modified quaternary ammonium salt is washed by using acetone with a mass fraction of 30% and a mass of 10 times that of the long-chain alkyl dimethyl tertiary amine quaternary ammonium salt for 9-10 times, and then the crude modified quaternary ammonium salt is dried at 50 DEG C for 10 h, and then the modified quaternary ammonium salt is obtained; banana peels are soaked in water with a mass of 20 times that of the banana peels at 30 DEG C for 1 h, and then boiled for 2 h, and then filtered through 16 layers of gauze, and then a filter residue and a filtrate A are obtained, and then the filter residue is added with water with a mass of 10 times that of the banana peels, and then boiled for 1 h, and then filtered through 16 layers of gauze, and then a filtrate B is obtained, and then the filtrate A and the filtrate B are mixed and placed at 60 DEG C for 3-4 h, and then a banana peel extract is prepared; the modified quaternary ammonium salt and the banana peel extract are mixed according to a mass ratio of 1:2, and then a bactericide is prepared; (4) The disinfection-treated sewage is self-flowed into a neutralization tank containing a neutralizing agent, and the neutralizing agent is prepared by mixing 30 g / L lecithin and 20 g / L Tween-80 in a phosphate buffer solution according to a volume ratio of 1:1, and then the sewage is allowed to stand for 10-20 min, and then neutralization-treated sewage is obtained; (5) The neutralization-treated sewage is self-flowed into an artificial wetland, and then transported to a breeding farm.

2. The method for purifying the aquaculture wastewater according to claim 1, wherein, The grid in step (1) is made of SS304, and the grid gap is 5 mm; the size of the water collecting well is 4.0 m x 1.5 m x 3.0 m, and the residence time is 40 min.

3. The method for purifying the aquaculture wastewater according to claim 1, wherein, The adsorption system in step (2) is a plastic barrel with a height of 1.5 m and an inner diameter of 1.2 m, 20 cm of sponge is laid at the bottom of the barrel, 10 cm of adsorbent is placed on the sponge, and then 1 layer of 10 cm of sponge is placed, and the above is repeated twice to form a sandwich type artificial purification system.

4. The method for purifying the aquaculture wastewater according to claim 1, wherein, The plants of the artificial wetland in step (5) are composed of Acorus calamus, Canna indica, Zizania aquatica, Eichhornia crassipes, Ceratophyllum demersum and Zantedeschia aethiopica.

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