A method for purifying seawater for aquaculture

Abstract

This invention provides a method for purifying seawater used in aquaculture, comprising the following steps: Step 1: After allowing seawater to settle, the supernatant is filtered, and a flocculant is added to the coarse filtrate before further filtration; Step 2: The filtrate is treated with a composite purification material and filtered to obtain purified seawater for aquaculture; The composite purification material is prepared as follows: S1: Tourmaline powder and maifanite powder are dried and calcined at high temperature to obtain calcined material; S2: Algae, EM bacteria, and puffed corn starch are mixed, and sodium alginate and polyvinyl alcohol are added and mixed, then dried to obtain a starch composite material; S3: Humic acid is dissolved in NaOH solution, Fe3O4 powder and polyethylene glycol are added, stirred and mixed, filtered, and washed to obtain composite material A; S4: The calcined material is mixed with silane coupling agent, glyoxal, starch composite material, and composite material A, washed, dried, and pulverized to obtain the composite purification material; This invention can effectively purify aquaculture water and has good performance.

Description

Technical Field

[0001] This invention relates to the field of aquaculture water technology, and in particular to a method for purifying and treating seawater used in aquaculture. Background Technology

[0002] With the improvement of people's living standards, consumers' recognition and demand for seafood are increasing, leading to the continuous development of the mariculture industry. Mariculture is the artificial cultivation of seafood in tidal flats and shallow seas, constituting an important method of aquaculture in my country. Before aquaculture, the seawater used needs to be purified to ensure that it meets standards and reduces the harm of pollutants to farmed aquatic products. Currently, the main methods used to treat aquaculture seawater are physical, chemical, and biological methods. Physical methods mainly remove particulate matter through sedimentation, adsorption, and filtration, but are not very effective at removing substances such as nitrogen and phosphorus. Chemical methods mainly use ultraviolet light, ozone, etc., to effectively remove viruses, bacteria, ammonia nitrogen, etc., but can cause secondary pollution. Biological methods mainly use microorganisms, algae, and the construction of artificial wetlands and ecological floating beds to remove ammonia nitrogen, total phosphorus, and organic matter. Although they are effective at removing nitrogen and phosphorus and do not cause secondary pollution, the construction and maintenance costs of wetlands and floating beds are relatively high, and there are problems such as the difficulty in fixing algae for long-term use during the cultivation process. Currently, there are also purification methods that combine physical, chemical, and biological methods, but the purification effect is still not good, and there are also problems such as the difficulty in recycling the purified substances. Summary of the Invention

[0003] In view of this, the present invention proposes a method for purifying seawater used in aquaculture.

[0004] The technical solution of this invention is implemented as follows:

[0005] A method for purifying seawater used in aquaculture includes the following steps:

[0006] Step 1: After the seawater has settled, take the supernatant and filter it through filter screen A to obtain coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through filter screen B to obtain filtrate.

[0007] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0008] The method for preparing the composite purification material is as follows:

[0009] S1. Take tourmaline powder and maifan stone powder, mix them, dry them, and then calcine them at high temperature to obtain calcined material;

[0010] S2. Take algae and EM bacteria and add them to puffed corn starch. Mix them evenly with high speed. Then add sodium alginate and polyvinyl alcohol and mix them. Dry the mixture to obtain starch composite material.

[0011] S3. Dissolve humic acid in an 8-10% NaOH solution, then add Fe3O4 powder and polyethylene glycol in sequence and stir to mix. After the reaction is complete, filter and wash the filter with distilled water to obtain composite material A.

[0012] S4. Place the calcined material in a reaction vessel, add silane coupling agent and stir to mix, then add glyoxal and starch composite material and stir to mix evenly, then add composite material A and stir to mix, and finally wash with distilled water, dry and pulverize to obtain composite purification material.

[0013] The flocculant includes: polyacrylamide, carboxymethyl starch, and Fe3O4 powder; the algae include: Chlorella vulgaris, green algae, and Spirulina, with a volume ratio of 2-3:1-3:1-2.

[0014] Furthermore, the filter screen A has a pore size of 8 to 12 mesh, and the filter screen B has a pore size of 40 to 60 mesh.

[0015] Furthermore, the composite purification material comprises the following raw materials in parts by weight: 50-60 parts puffed corn starch, 40-50 parts humic acid, 20-35 parts Fe3O4 powder, 20-30 parts tourmaline powder, 20-30 parts maifanite powder, 25-30 parts algae, 25-30 parts EM bacteria, 16-20 parts sodium alginate, 15-18 parts polyvinyl alcohol, 15-18 parts polyethylene glycol, and 12-16 parts silane coupling agent.

[0016] Furthermore, the preparation method of the flocculant is as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 10-15 min, then a 25% glutaraldehyde solution is added, the mixture is stirred and reacted for 3-4 h, and then filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. It is dried to constant weight at a temperature of 40-60℃ and then pulverized into 50-60 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 2-3:1-2:25-30:4-6:0.4-0.6.

[0017] Furthermore, the preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under a nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying, and then pulverized to obtain Fe3O4 powder.

[0018] Furthermore, the NaOH solution has a mass fraction of 2.0%; and the Fe3O4 powder has a particle size of 40-60 mesh.

[0019] Furthermore, the silane coupling agent is one or a combination of two or more of silane coupling agents KH-550, KH-560, or KH-570.

[0020] Furthermore, in step S1 above, the particle size of the tourmaline powder is 80-100 mesh, the particle size of the maifanite powder is 80-100 mesh, the drying conditions are drying at 100-105℃ for 3-4 hours, and the high-temperature calcination conditions are calcination at 700-900℃ for 3-5 hours.

[0021] Furthermore, in step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 6 to 8 days at each salinity, they are transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0022] Furthermore, in step S4 above, the stirring and mixing conditions are set at a temperature of 40-50°C and a stirring speed of 500-700 r / min; the drying conditions are dried to constant weight at a temperature of 25-40°C.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. In this invention, the seawater to be purified is first allowed to stand to remove large solid particles. The supernatant is then filtered through filter screen A to remove fine particulate matter. Adding a flocculant can remove some water-insoluble matter, suspended matter, harmful organisms, organic matter, and other pollutants. Finally, the seawater is treated with a composite purification material prepared from humic acid, puffed corn starch, Fe3O4 powder, algae, and EM bacteria. This process can more effectively remove pollutants such as ammonia nitrogen and organic matter from the seawater. By using the method of this invention to perform multiple purification treatments on seawater, the water quality of aquaculture can be improved, the harm of seawater pollutants to aquaculture products can be reduced, thereby promoting the growth of aquaculture products and improving their quality.

[0025] 2. In the preparation of the composite purification material, this invention first calcines maifanite and tourmaline to increase their specific surface area and porosity, thereby improving the purification and adsorption effect. Cultivating algae and EM bacteria enhances their salt tolerance, allowing for better purification in seawater. The cultivated algae and EM bacteria are then combined with puffed corn starch, which provides a stable substrate environment for the algae and EM bacteria, improving their survival stability and maintaining their concentration in the purified water, thus increasing the purification and degradation efficiency. Finally, combining humic acid and Fe3O4 powder improves the stability of the humic acid, further enhancing its effectiveness. The process enhances the adsorption and purification of pollutants. Maifan stone, tourmaline, and puffed corn starch are first combined. Maifan stone and tourmaline can regulate the pH of the purified seawater while also promoting the growth of algae and EM bacteria, thus improving the purification effect. During the purification process, humic acid, puffed corn starch, maifan stone, and tourmaline can adsorb ammonia nitrogen, organic pollutants, and other substances in the seawater, facilitating the absorption and utilization of these pollutants by algae and EM bacteria loaded on the puffed corn starch. This promotes the degradation of harmful substances and achieves better purification. Furthermore, after degradation by algae and EM bacteria, humic acid and puffed corn starch can also further absorb pollutants, continuously promoting degradation.

[0026] 3. The composite purification material prepared by this invention combines algae and EM bacteria for immobilization, which can achieve the purpose of reuse and improve the efficiency of use. In addition, the Fe3O4 powder is loaded with magnetic material, which also facilitates subsequent separation and has high recycling efficiency. Detailed Implementation

[0027] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0028] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0029] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0030] The puffed corn starch used in this invention is produced by Shandong Xinfulai Biotechnology Co., Ltd.; the EM strain in this invention is produced by Beihai Yiqiang Biotechnology Co., Ltd., and is named EM strain powder. Its main components are various microbial strains such as Bifidobacterium, Lactic acid bacteria, Bacillus, photosynthetic bacteria, and yeast, with a live bacteria count of 100 billion / gram.

[0031] Example 1

[0032] The composite purification material in this implementation includes the following raw materials in parts by weight: 50 parts puffed corn starch, 40 parts humic acid, 20 parts Fe3O4 powder, 20 parts tourmaline powder, 20 parts maifan stone powder, 25 parts algae, 25 parts EM bacteria, 16 parts sodium alginate, 15 parts polyvinyl alcohol, 15 parts polyethylene glycol, and 12 parts silane coupling agent.

[0033] The method for purifying seawater used in aquaculture implemented herein includes the following steps:

[0034] Step 1: After the seawater has settled, take the supernatant and filter it through a filter screen A with an 8-mesh pore size to obtain a coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through a filter screen B with a 40-mesh pore size to obtain a filtrate.

[0035] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0036] The method for preparing the composite purification material is as follows:

[0037] S1. Take tourmaline powder with a particle size of 80 mesh and maifan stone powder with a particle size of 80 mesh, mix them, dry them at 100-105℃ for 3 hours, and then heat them to 700℃ for calcination for 3-5 hours to obtain calcined material.

[0038] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 2:1:1 and add EM bacteria to puffed corn starch. Mix evenly by high-speed stirring. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0039] S3. Humic acid was completely dissolved in an 8% NaOH solution. Fe3O4 powder and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0040] S4. Place the calcined material in a reaction vessel, heat it to 40°C, add silane coupling agent KH-550 and stir and mix at a stirring speed of 500 r / min, then add glyoxal and starch composite material and stir and mix evenly, then add composite material A and stir and mix, finally wash with distilled water, dry at 25°C to constant weight, pulverize, and obtain composite purification material.

[0041] The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 10 min, followed by the addition of a 25% glutaraldehyde solution. After stirring and reacting for 3 h, the mixture is filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. After drying at 40°C to constant weight, it is pulverized into 50 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 2:1:25:4:0.4.

[0042] The preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then 2.0% NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying. After pulverization, Fe3O4 powder with a particle size of 40 mesh is obtained.

[0043] In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 6 to 8 days at each salinity, they are transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0044] Example 2

[0045] The composite purification material used in this implementation comprises the following raw materials in parts by weight: 60 parts puffed corn starch, 50 parts humic acid, 35 parts Fe3O4 powder, 30 parts tourmaline powder, 30 parts maifan stone powder, 30 parts algae, 30 parts EM bacteria, 20 parts sodium alginate, 18 parts polyvinyl alcohol, 18 parts polyethylene glycol, and 16 parts silane coupling agent.

[0046] The method for purifying seawater used in aquaculture implemented herein includes the following steps:

[0047] Step 1: After the seawater has settled, take the supernatant and filter it through a 12-mesh filter A to obtain coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through a 60-mesh filter B to obtain filtrate.

[0048] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0049] The method for preparing the composite purification material is as follows:

[0050] S1. Take tourmaline powder with a particle size of 100 mesh and maifan stone powder with a particle size of 100 mesh, mix them, dry them at 100-105℃ for 4 hours, and then heat them to 900℃ for calcination for 3-5 hours to obtain calcined material.

[0051] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 3:3:2, add EM bacteria to puffed corn starch, stir at high speed to mix evenly, then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0052] S3. Humic acid was completely dissolved in a 10% NaOH solution. Fe3O4 powder and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0053] S4. Place the calcined material in a reaction vessel, heat it to 50°C, add silane coupling agent KH-560 and stir and mix at a stirring speed of 700 r / min, then add glyoxal and starch composite material and stir and mix evenly, then add composite material A and stir and mix, finally wash with distilled water, dry at 40°C to constant weight, pulverize, and obtain composite purification material.

[0054] The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 15 min, followed by the addition of a 25% glutaraldehyde solution. After stirring and reacting for 4 h, the mixture is filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. After drying at 60°C to constant weight, it is pulverized into 60 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 3:2:30:6:0.6.

[0055] The preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then 2.0% NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying. After pulverization, Fe3O4 powder with a particle size of 60 mesh is obtained.

[0056] In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 8 days at each salinity, the culture is transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0057] Example 3

[0058] The composite purification material used in this implementation comprises the following raw materials in parts by weight: 55 parts puffed corn starch, 42 parts humic acid, 24 parts Fe3O4 powder, 25 parts tourmaline powder, 23 parts maifan stone powder, 27 parts algae, 26 parts EM bacteria, 18 parts sodium alginate, 16 parts polyvinyl alcohol, 18 parts polyethylene glycol, and 13 parts silane coupling agent.

[0059] The method for purifying seawater used in aquaculture implemented herein includes the following steps:

[0060] Step 1: After the seawater has settled, take the supernatant and filter it through a 10-mesh filter A to obtain coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through a 45-mesh filter B to obtain filtrate.

[0061] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0062] The method for preparing the composite purification material is as follows:

[0063] S1. Take tourmaline powder with a particle size of 90 mesh and maifan stone powder with a particle size of 80 mesh, mix them, dry them at 100-105℃ for 3.5h, and then heat them to 850℃ for calcination for 3-5h to obtain calcined material.

[0064] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 2:3:2 and add EM bacteria to puffed corn starch. Mix evenly by high-speed stirring. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0065] S3. Humic acid was completely dissolved in a 9% NaOH solution. Fe3O4 powder and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0066] S4. Place the calcined material in a reaction vessel, heat it to 45°C, add silane coupling agent KH-570 and stir and mix at a stirring speed of 600 r / min, then add glyoxal and starch composite material and stir and mix evenly, then add composite material A and stir and mix, finally wash with distilled water, dry at 30°C to constant weight, pulverize, and obtain composite purification material.

[0067] The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 12 min, followed by the addition of a 25% glutaraldehyde solution. After stirring and reacting for 4 h, the mixture is filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. It is dried to constant weight at a temperature of 40–60 °C and then pulverized into 55 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 2:2:26:5:0.4.

[0068] The preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then 2.0% NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying. After pulverization, Fe3O4 powder with a particle size of 60 mesh is obtained.

[0069] In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 7 days at each salinity, the culture is transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0070] Example 4

[0071] The composite purification material used in this implementation comprises the following raw materials in parts by weight: 53 parts puffed corn starch, 45 parts humic acid, 30 parts Fe3O4 powder, 28 parts tourmaline powder, 26 parts maifan stone powder, 26 parts algae, 29 parts EM bacteria, 19 parts sodium alginate, 17 parts polyvinyl alcohol, 16 parts polyethylene glycol, and 15 parts silane coupling agent.

[0072] The method for purifying seawater used in aquaculture implemented herein includes the following steps:

[0073] Step 1: After the seawater has settled, take the supernatant and filter it through a filter screen A with an 8-mesh pore size to obtain a coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through a filter screen B with a 50-mesh pore size to obtain a filtrate.

[0074] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0075] The method for preparing the composite purification material is as follows:

[0076] S1. Take tourmaline powder with a particle size of 100 mesh and maifan stone powder with a particle size of 90 mesh, mix them, dry them at 100-105℃ for 4 hours, and then calcine them at 750℃ for 3 hours to obtain calcined material.

[0077] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 3:1:1 and add EM bacteria to puffed corn starch. Mix evenly by high-speed stirring. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0078] S3. Humic acid was completely dissolved in an 8.5% NaOH solution. Fe3O4 powder and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0079] S4. Place the calcined material in a reaction vessel and heat it to 50°C. Add silane coupling agent KH-550 and silane coupling agent KH-560 at a weight ratio of 1:1 and stir and mix them at a stirring speed of 650 r / min. Then add glyoxal and starch composite material and stir and mix evenly. Then add composite material A and stir and mix. Finally, wash with distilled water, dry at 35°C to constant weight, pulverize, and obtain composite purification material.

[0080] The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 14 min, followed by the addition of a 25% glutaraldehyde solution. After stirring and reacting for 3.5 h, the mixture is filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. After drying at 50°C to constant weight, it is pulverized into 50 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 3:1:28:6:0.5.

[0081] The preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then 2.0% NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying. After pulverization, Fe3O4 powder with a particle size of 45 mesh is obtained.

[0082] In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 6 days at each salinity, the culture is transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0083] Example 5

[0084] The composite purification material used in this implementation comprises the following raw materials in parts by weight: 58 parts puffed corn starch, 48 parts humic acid, 32 parts Fe3O4 powder, 22 parts tourmaline powder, 28 parts maifan stone powder, 28 parts algae, 27 parts EM bacteria, 17 parts sodium alginate, 15 parts polyvinyl alcohol, 17 parts polyethylene glycol, and 14 parts silane coupling agent.

[0085] The method for purifying seawater used in aquaculture implemented herein includes the following steps:

[0086] Step 1: After the seawater has settled, take the supernatant and filter it through a 12-mesh filter A to obtain coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through a 48-mesh filter B to obtain filtrate.

[0087] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0088] The method for preparing the composite purification material is as follows:

[0089] S1. Take tourmaline powder with a particle size of 80 mesh and maifan stone powder with a particle size of 100 mesh, mix them, dry them at 100-105℃ for 3 hours, and then heat them to 800℃ for calcination for 3 hours to obtain calcined material.

[0090] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 3:2:2 and add EM bacteria to puffed corn starch. Mix evenly by high-speed stirring. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0091] S3. Humic acid was completely dissolved in a 9.5% NaOH solution. Fe3O4 powder and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0092] S4. Place the calcined material in a reaction vessel, heat it to 40°C, add a coupling agent composed of silane coupling agent KH-550, silane coupling agent KH-560 and silane coupling agent KH-570 in a weight ratio of 1:2:1, and stir and mix at a stirring speed of 550 r / min. Then add glyoxal and starch composite material and stir and mix evenly. Then add composite material A and stir and mix. Finally, wash with distilled water, dry at 40°C to constant weight, pulverize, and obtain composite purification material.

[0093] The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 13 min, followed by the addition of a 25% glutaraldehyde solution. After stirring and reacting for 3 h, the mixture is filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. After drying at 45°C to constant weight, it is pulverized into 60 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 3:1:27:4:0.6.

[0094] The preparation method of the Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; under nitrogen atmosphere, FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution, and then 2.0% NaOH solution is slowly added dropwise while stirring to obtain a crude gel. The crude gel is washed with distilled water until the pH is neutral, and then the washed gel is placed in an oven for drying. After pulverization, Fe3O4 powder with a particle size of 50 mesh is obtained.

[0095] In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 8 days at each salinity, the culture is transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

[0096] Comparative Example 1

[0097] The composite purification material in this comparative example includes the following raw materials in parts by weight: 50 parts puffed corn starch, 40 parts humic acid, 20 parts Fe3O4 powder, 20 parts tourmaline powder, 20 parts maifan stone powder, 25 parts algae, 25 parts EM bacteria, 16 parts sodium alginate, 15 parts polyvinyl alcohol, 15 parts polyethylene glycol, and 12 parts silane coupling agent.

[0098] The seawater purification method for aquaculture in this comparative example includes the following steps:

[0099] Step 1: After the seawater has settled, take the supernatant and filter it through a filter screen A with an 8-mesh pore size to obtain a coarse filtrate. Then filter the coarse filtrate through a filter screen B with a 40-mesh pore size to obtain a filtrate.

[0100] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0101] The method for preparing the composite purification material is as follows:

[0102] S1. Take tourmaline powder with a particle size of 80 mesh and maifan stone powder with a particle size of 80 mesh, mix them, dry them at 100-105℃ for 3 hours, and then heat them to 700℃ for calcination for 3-5 hours to obtain calcined material.

[0103] S2. Take algae composed of Chlorella pyrenoidosa, green algae and Spirulina in a volume ratio of 2:1:1 and add EM bacteria to puffed corn starch. Mix evenly by high-speed stirring. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material.

[0104] S3. Humic acid was completely dissolved in a 10% NaOH solution. Fe3O4 powder with a particle size of 40 mesh and polyethylene glycol were added sequentially and stirred. After the reaction was completed, the mixture was filtered and the filter was washed with distilled water to obtain composite material A.

[0105] S4. Place the calcined material in a reaction vessel, heat it to 40°C, add silane coupling agent KH-550 and stir and mix at a stirring speed of 500 r / min. Then add glyoxal and starch composite material and stir and mix evenly. Then add composite material A and stir and mix. Finally, wash with distilled water, dry at 25°C to constant weight, pulverize, and obtain composite purification material.

[0106] The difference between this comparative example and Example 1 is that the step of adding flocculant in step one is omitted, and filtration is performed directly using filter screen B. The specific operation process is as described above.

[0107] Comparative Example 2

[0108] The composite purification material in this comparative example includes the following raw materials in parts by weight: 50 parts puffed corn starch, 40 parts humic acid, 20 parts Fe3O4 powder, 20 parts tourmaline powder, 20 parts maifan stone powder, 25 parts algae, 25 parts EM bacteria, 16 parts sodium alginate, 15 parts polyvinyl alcohol, 15 parts polyethylene glycol, and 12 parts silane coupling agent.

[0109] The seawater purification method for aquaculture in this comparative example includes the following steps:

[0110] Step 1: After the seawater has settled, take the supernatant and filter it through a filter screen A with an 8-mesh pore size to obtain a coarse filtrate. Add a flocculant made of polyacrylamide, carboxymethyl starch and Fe3O4 powder to the coarse filtrate, stir and mix, and then filter it through a filter screen B with a 40-mesh pore size to obtain a filtrate.

[0111] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0112] The method for preparing the composite purification material is as follows:

[0113] Tourmaline powder with a particle size of 80 mesh, maifanite powder with a particle size of 80 mesh, Fe3O4 powder, puffed corn starch, polyvinyl alcohol, polyethylene glycol, and silane coupling agent KH-550 were mixed at a stirring speed of 500 r / min. Then, humic acid, algae composed of Chlorella vulgaris, green algae, and Spirulina in a volume ratio of 2:1:1, EM bacteria, and sodium alginate were added and mixed. The mixture was then dried at 25°C to constant weight, pulverized, and the composite purification material was obtained.

[0114] The difference between this comparative example and Example 1 is that the preparation methods of the flocculant and the composite purification material are different.

[0115] Comparative Example 3

[0116] The composite purification material in this comparative example includes the following raw materials in parts by weight: 80 parts diatomaceous earth, 40 parts humic acid, 20 parts Fe3O4 powder, 25 parts algae, 25 parts EM bacteria, 16 parts sodium alginate, 15 parts polyvinyl alcohol, 15 parts polyethylene glycol, and 12 parts silane coupling agent.

[0117] The seawater purification method for aquaculture in this comparative example includes the following steps:

[0118] Step 1: After the seawater has settled, take the supernatant and filter it through a filter screen A with an 8-mesh pore size to obtain a coarse filtrate. Add a flocculant made of polyacrylamide, carboxymethyl starch and Fe3O4 powder to the coarse filtrate, stir and mix, and then filter it through a filter screen B with a 40-mesh pore size to obtain a filtrate.

[0119] Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture.

[0120] The method for preparing the composite purification material is as follows:

[0121] Diatomaceous earth, Fe3O4 powder, polyvinyl alcohol, polyethylene glycol, and silane coupling agent KH-550 were mixed at a stirring speed of 500 r / min. Then, humic acid, algae composed of Chlorella vulgaris, green algae, and Spirulina in a volume ratio of 2:1:1, and sodium alginate were added and mixed. The mixture was then dried at 25°C to constant weight and pulverized to obtain a composite purification material.

[0122] The difference between this comparative example and Comparative Example 2 is that the preparation method of the composite purification material does not contain tourmaline powder, maifanite powder, or puffed corn starch, but adds 80 parts of diatomaceous earth, and the preparation methods are different.

[0123] Experimental procedure:

[0124] The seawater used in the experiment of this invention was taken from the unpurified seawater of the Litopenaeus vannamei farming area in Huiwen Town, Wenchang City, Hainan Province. The seawater was divided into 9 groups. Groups 1 to 5 were purified using the methods of Examples 1 to 5 of this invention. Groups 6 to 8 were purified using the methods of Comparative Examples 1 to 3. Group 9 was purified using commercially available microbial agents as a positive control group.

[0125] The commercially available microbial inoculant is manufactured by Shandong Lvbao Biotechnology Co., Ltd., and its brand name is Aquatic Water Purifier. It mainly contains a complex of bacteria, including photosynthetic bacteria, Bacillus, yeast, Actinobacteria, and lactic acid bacteria, with an effective live bacteria count of ≥20 billion.

[0126] The pH and NH4 levels of seawater before and after purification were measured. + -N,PO4 3- -P, NO2 - The concentration index of -N was determined by taking the average of 6 tests per group. The test index standards and calculation formulas are as follows:

[0127] (1) Reference method for indicator testing:

[0128] ①The pH value was measured using a pH meter;

[0129] ②NH4 + -N concentration is determined according to GB / T12763.4-2007 Sodium hypobromite oxidation method;

[0130] ③PO4 3- -P concentration was determined according to GB 11893-1989 Determination of Total Phosphorus in Water - Ammonium Molybdate Spectrophotometric Method;

[0131] ④NO2 - -N concentration was determined according to the diazo coupling method in GB / T 17378-1998.

[0132] (2) Removal rate calculation formula: A=(C0-C1) / C0×100%;

[0133] Where A is NH4 + -N,PO4 3- -P, NO2 - The removal rate of -N, C0 is the NH4+ in unpurified seawater. + -N, NO2 - The initial concentration of -N, C1 is the NH4+ content in the purified seawater. + -N,PO4 3- -P, NO2 - The concentration of -N was measured; the experimental results are shown in Table 1 below.

[0134] Table 1 Seawater Purification Status

[0135]

[0136] The above results show that after seawater is purified by the method of the present invention, NH4 + -N removal rate was 97.28–99.01%, PO4 removal rate was 97.28–99.01%. 3- -P removal rate was 97.86–99.12%, NO2 removal rate was 97.86–99.12%. - The removal rate of NH4+ was 97.50%–98.98%. After seawater was purified using methods 1–3, the NH4+ removal rate was significantly reduced. + -N removal rate was 88.12%–93.46%, PO4 removal rate was 98.12%–93.46%, 3- -P removal rate was 89.37–94.05%, NO2 removal rate was 100%. - The removal rate of -N is 88.51%–92.37%, which is relatively poor compared to commercially available purification products. The multi-step purification method of this invention, along with the synergistic effect of flocculants and composite purification materials, can effectively purify seawater used in aquaculture. The process is convenient and the purification effect is good, while comparative examples 1–3 and commercially available microbial inoculants have not achieved this effect. Therefore, the purification method of this invention has broad application prospects.

[0137] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for purifying seawater used in aquaculture, characterized in that, Includes the following steps: Step 1: After the seawater has settled, take the supernatant and filter it through filter screen A to obtain coarse filtrate. Add flocculant to the coarse filtrate, stir and mix, and then filter it through filter screen B to obtain filtrate. Step 2: After adding the filtrate to the composite purification material for treatment, filter it to obtain purified seawater for aquaculture. The method for preparing the composite purification material is as follows: S1. Take tourmaline powder and maifan stone powder, mix them, dry them, and then calcine them at high temperature to obtain calcined material; S2. Take algae and EM bacteria and add them to puffed corn starch. Stir and mix evenly. Then add sodium alginate and polyvinyl alcohol, stir and mix, and then dry to obtain starch composite material. S3. Dissolve humic acid in an 8-10% NaOH solution, then add Fe3O4 powder and polyethylene glycol in sequence and stir to mix. After the reaction is complete, filter and wash the filter with distilled water to obtain composite material A. S4. Place the calcined material in a reaction vessel, add silane coupling agent and stir to mix, then add glyoxal and the starch composite material in S2 above and stir to mix evenly, then add composite material A and stir to mix, and finally wash with distilled water, dry and pulverize to obtain composite purification material. The algae include Chlorella pyrenoidosa, green algae, and Spirulina, with a volume ratio of 2~3:1~3:1~2; The flocculant is prepared as follows: polyacrylamide and carboxymethyl starch are dissolved in distilled water, then Fe3O4 powder is added and ultrasonically dispersed for 10-15 min, then 25% glutaraldehyde solution is added, the mixture is stirred and reacted for 3-4 h, and then filtered to obtain filter residue. The filter residue is washed with distilled water until neutral and then placed in a drying oven. It is dried to constant weight at a temperature of 40-60℃ and then pulverized into 50-60 mesh to obtain the flocculant. The mass ratio of polyacrylamide, carboxymethyl starch, distilled water, Fe3O4 powder, and glutaraldehyde solution is 2-3:1-2:25-30:4-6:0.4-0.

6.

2. The method for purifying seawater for aquaculture according to claim 1, characterized in that, The filter screen A has a pore size of 8-12 mesh, and the filter screen B has a pore size of 40-60 mesh.

3. The method for purifying seawater for aquaculture according to claim 1, characterized in that, The composite purification material comprises the following raw materials in parts by weight: 50-60 parts puffed corn starch, 40-50 parts humic acid, 20-35 parts Fe3O4 powder, 20-30 parts tourmaline powder, 20-30 parts maifan stone powder, 25-30 parts algae, 25-30 parts EM bacteria, 16-20 parts sodium alginate, 15-18 parts polyvinyl alcohol, 15-18 parts polyethylene glycol, and 12-16 parts silane coupling agent.

4. The method for purifying seawater for aquaculture according to claim 1, characterized in that, The preparation method of Fe3O4 powder is as follows: FeCl2, FeCl3, distilled water, and NaOH solution are taken in a weight ratio of 1:2:30:16; FeCl2 and FeCl3 are added to distilled water and fully dissolved to obtain a solution under nitrogen atmosphere; then NaOH solution is slowly added dropwise and stirred to obtain a crude gel; the crude gel is washed with distilled water until the pH is neutral; then the washed gel is placed in an oven for drying; and then pulverized to obtain Fe3O4 powder.

5. The method for purifying seawater for aquaculture according to claim 4, characterized in that, The NaOH solution has a mass fraction of 2.0%; the Fe3O4 powder has a particle size of 40-60 mesh.

6. The method for purifying seawater for aquaculture according to claim 1, characterized in that, The silane coupling agent is one or a combination of two or more of the following: silane coupling agent KH-550, silane coupling agent KH-560, or silane coupling agent KH-570.

7. The method for purifying seawater for aquaculture according to claim 1, characterized in that, In step S1 above, the particle size of the tourmaline powder is 80-100 mesh, the particle size of the maifanite powder is 80-100 mesh, the drying conditions are drying at 100-105℃ for 3-4 hours, and the high-temperature calcination conditions are calcination at 700-900℃ for 3-5 hours.

8. The method for purifying seawater for aquaculture according to claim 1, characterized in that, In step S2 above, the algae cultivation method is as follows: Chlorella proteoglycans, green algae, and Spirulina are inoculated into conical flasks containing f2 algae culture media with salinities of 8‰, 16‰, 24‰, and 32‰, respectively. After culturing for 6-8 days at each salinity, they are transferred. Finally, qualified strains are selected from the f2 algae culture media with a salinity of 32‰, and after centrifugation and concentration, the cultured Chlorella proteoglycans, green algae, and Spirulina are obtained.

9. The method for purifying seawater for aquaculture according to claim 1, characterized in that, In step S4 above, the stirring and mixing conditions are set at a temperature of 40~50℃ and a stirring speed of 500~700r / min; the drying conditions are dried to constant weight at a temperature of 25~40℃.

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