Efficient SPF and biotoxicity-free water treatment method

Abstract

The invention relates to the technical field of aquaculture, and particularly discloses an efficient SPF and biotoxicity-free water treatment method which comprises the following steps: S1, filtering aquaculture water; s2, modified bentonite and an organic chelating agent are added into the filtered aquaculture water, and then a stirring reaction is performed; after the reaction is completed, standing and precipitating to obtain purified water; s3, modified nano titanium dioxide is added into the purified water, then ultraviolet irradiation treatment is performed, and filtering is performed after ultraviolet irradiation treatment. According to the treatment method, large-particle impurities, small particles, organic matters, heavy metal ions and specific pathogens such as WSSV and EMS in the aquaculture water are removed through multiple filtration and purification procedures, meanwhile, introduction of biotoxic substances is avoided, and it is ensured that the treated aquaculture water meets the standard of efficient SPF and no biotoxicity.

Description

Technical Field

[0001] The present invention relates to the technical field of aquaculture water treatment, and in particular to a water treatment method with high SPF efficiency and no biological toxicity. Background Art

[0002] As a key aquaculture species, shrimp boast numerous advantages, including rapid growth, a long breeding season, high stocking density, and strong adaptability, occupying a key position in the global aquaculture industry. In shrimp farming, aquaculture water is a critical environmental factor in maintaining shrimp survival and growth. High-quality aquaculture water provides shrimp with optimal temperature, pH, dissolved oxygen, and other conditions, ensuring their healthy growth. The quality of aquaculture water is directly related to shrimp growth rate, survival rate, and ultimately, the profitability of aquaculture. As shrimp farming continues to expand, the requirements for aquaculture water treatment technology are becoming increasingly stringent. Efficient, environmentally friendly, and safe water treatment methods have become a key requirement for the industry's development.

[0003] At present, there are many problems in the water treatment technology related to shrimp farming. In the traditional pond farming model, a large amount of external water is used for farming. Frequent water changes not only waste water resources, but also make it difficult to control water quality and easily introduce external pathogens, such as white spot disease virus (WSSV) and Vibrio parahaemolyticus (EMS). These pathogens seriously threaten the health of shrimp and lead to a decrease in farming survival rate. Although some factory farming models have adopted recirculating water farming technology, the existing water treatment process is not perfect. Chemical agents with biological toxicity may be used in the water treatment process, which will not only remain in the aquaculture water and affect the quality of shrimp, but may also cause pollution to the environment. In addition, the water purification effect of some recirculating water aquaculture systems is limited, and they cannot effectively remove harmful substances such as ammonia nitrogen and nitrite in the water, making it difficult for the aquaculture water quality to meet the standards in the long term, which is not conducive to the sustainable and healthy farming of shrimp.

[0004] In summary, the core problem facing existing shrimp aquaculture water treatment technology is: how to ensure that the aquaculture water is free of biotoxicity while achieving efficient SPF (specific pathogen-free) treatment, so as to ensure that the content of specific pathogens (such as WSSV, EMS, etc.) and biotoxic substances (such as residual chemicals) in the aquaculture water are controlled below safety standards. Summary of the Invention

[0005] In view of this, the present invention proposes a water treatment method with high SPF efficiency and no biological toxicity to solve the above problems.

[0006] The technical solution of the present invention is achieved as follows:

[0007] A water treatment method with high SPF efficiency and no biological toxicity, comprising the following steps:

[0008] S1. Filter the aquaculture water through a coarse filter, a fiber filter cloth, and an activated carbon filter layer in sequence for 2-4 hours; the pore size of the coarse filter is 2-5 mm; the pore size of the fiber filter cloth is 0.1-0.5 mm; the iodine value of the activated carbon filter layer is 500-800 mg / g;

[0009] S2, adding modified bentonite and an organic chelating agent to the filtered aquaculture water and stirring the reaction for 1-2 hours, the modified bentonite addition amount is 2-6 kg / m3, and the organic chelating agent addition amount is 0.5-1 kg / m3; after the reaction is completed, the reaction is allowed to settle for 4-6 hours, and purified water is obtained after filtering through a filter membrane;

[0010] S3. Add modified nano-titanium dioxide to the purified water, with the addition amount of modified nano-titanium dioxide being 0.2-0.5 kg / m3; then perform ultraviolet irradiation treatment, with the ultraviolet wavelength being 250-300 nm and the irradiation intensity being 10-20 mW / cm 2 The irradiation time is 1-2h, and the filtration is carried out after ultraviolet irradiation treatment.

[0011] By adopting the above technical solution, in S1, the 2-5mm pore size of the coarse filter can intercept large particles of impurities such as leftover bait and feces, preventing them from subsequently clogging equipment or affecting water quality. The 0.1-0.5mm pore size of the fiber filter cloth further filters out tiny particles, reducing suspended matter in the water. The activated carbon filter layer, with an iodine value of 500-800mg / g, can adsorb organic matter, some heavy metal ions, and odors in the water, improving water quality while removing some impurities that may carry pathogens. In S2, modified bentonite and organic chelating agents work synergistically. Modified bentonite has a stronger adsorption capacity and can adsorb colloidal substances, some pathogens, and residual tiny impurities in the water. The organic chelating agent can chelate heavy metal ions in the water, forming a stable complex and reducing the biological toxicity of heavy metals. After the two react, they are allowed to settle and filtered through a membrane to further remove the precipitate and unreacted substances, thereby improving the water purity. In S3, the modified nano-titanium dioxide added to the water reacts with ultraviolet light at 250-550nm, generating a photocatalytic reaction that produces highly oxidizing reactive oxygen species, such as hydroxyl radicals and superoxide anion radicals. These reactive oxygen species can destroy the cellular structure of pathogens, denature proteins, and degrade nucleic acids, effectively killing specific pathogens such as WSSV and EMS. They also degrade residual organic pollutants in the water, converting them into harmless substances such as carbon dioxide and water. Finally, filtration removes any remaining modified nano-titanium dioxide particles, ensuring that the treated water is free of impurities and pathogens, meeting safe aquaculture standards.

[0012] Through multiple filtration and purification processes, large impurities, fine particles, organic matter, heavy metal ions, and specific pathogens such as WSSV and EMS are removed from the aquaculture water, while also preventing the introduction of biotoxic substances. This ensures that the treated aquaculture water meets high-efficiency SPF and is biotoxic-free. This provides a safe and stable growth environment for shrimp, significantly reducing the risk of disease infection, increasing shrimp survival rates, and ensuring their healthy growth, thereby improving aquaculture profitability and promoting the sustainable development of the aquaculture industry.

[0013] Furthermore, the modified bentonite is prepared by the following method: adding bentonite to a chitosan solution with a mass fraction of 2-5%, with the mass ratio of bentonite to chitosan solution being 1:(5-10), stirring and reacting at 50-70°C for 3-5h, and after the reaction is completed, filtering and drying to obtain the modified bentonite.

[0014] By adopting the above technical solution, chitosan inherently possesses certain antibacterial properties, and its functional groups, such as amino and hydroxyl groups, increase the surface active sites of bentonite, improving its adsorption performance. When treating aquaculture water, the modified bentonite leverages these properties to more efficiently adsorb impurities and pathogens in the water. Through subsequent precipitation and filtration steps, these impurities are removed from the water, reducing the presence of pathogens in the aquaculture water and lowering the risk of shrimp disease. Modified bentonite, prepared using a specific method, has enhanced adsorption capacity for impurities and pathogens in aquaculture water without introducing biotoxic substances. This helps to more effectively remove microparticles and colloids in the water that may carry pathogens such as WSSV and EMS, further improving water cleanliness, reducing the risk of shrimp disease, and ensuring a healthy growth environment for shrimp.

[0015] Furthermore, the modified nano-titanium dioxide was prepared by the following method: placing the nano-titanium dioxide in a nitric acid solution with a concentration of 8-12% and ultrasonically cleaning it for 25-35 minutes at an ultrasonic frequency of 30-50kHz and an ultrasonic power of 200-400W, followed by vacuum drying at 55-65°C for 2-3 hours to obtain pretreated nano-titanium dioxide; placing the pretreated nano-titanium dioxide in a Tris-HCl buffer solution, sequentially adding dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea, and magnetically stirring under a nitrogen atmosphere, and then dropping ammonia water with a concentration of 4-6% to adjust the pH to 9.4-9.6 and evaporating the solution. The reaction was carried out at 33-37°C for 1.8-2.2 hours, and then the temperature was raised to 43-47°C, 0.04-0.06 mol / L ascorbic acid was added, and the mixture was protected from light for 10-15 hours. The mixture was then placed in a tube furnace, and a mixture of argon and hydrogen sulfide was introduced at a rate of 5-10°C / min to 450°C, and the mixture was kept warm for 1.9-2.1 hours. The mixture was then naturally cooled to 200°C and quenched with nitrogen to obtain a sulfurized material. The sulfurized material was then placed in a 0.01-0.02 mol / L terpyridine ruthenium chloride ethanol solution at a solid-liquid ratio of g / mL of 1:(4-6), and a wavelength of 365 nm and 10-15 mW / cm was applied. 2 The mixture was irradiated with ultraviolet light for 35-45 minutes, and then centrifuged to obtain the solid matter, which was vacuum dried at 55-65° C. for 4-6 hours to obtain modified nano-titanium dioxide.

[0016] Furthermore, the mass volume ratio of pretreated nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea, and Tris-HCl buffer is (1.0-1.5):(2.0-2.5):(24-36):(4-6):1.0 g / L, magnetic stirring is carried out at 600-1000 r / min for 30-40 min, the pH of the Tris-HCl buffer is 8.5-9.0, and the volume ratio of argon to hydrogen sulfide in the argon and hydrogen sulfide mixture is 95:5.

[0017] By adopting the above technical solution, the absorption edge of modified nano-titanium dioxide is red-shifted to the visible light region, and more electron-hole pairs are excited under ultraviolet and visible light to enhance the removal effect of pollutants. The zinc sulfide formed in the sulfur doping process forms a heterojunction with titanium dioxide, and the sulfur-rich surface of zinc sulfide and Hg 2+ 、Cd 2+etc. to form a strong coordination complex, and the adsorption capacity is significantly improved. By modifying the surface of nano-titanium dioxide, a polydopamine layer is deposited, and the polydopamine layer adsorbs soluble organic matter, reducing its competition with ammonia nitrogen for active sites, thereby effectively removing ammonia nitrogen. Titanium dioxide is excited to produce hydroxyl radicals, hydrogen peroxide and other active oxygen species, which destroy bacterial cell membrane lipids and viral capsid proteins. The sulfide titanium dioxide obtained by sulfur doping treatment in the modification process of this application produces a mild thermal effect under light, which accelerates the denaturation of pathogen proteins and further enhances the removal effect of pathogens. By placing it in a tripyridine ruthenium chloride ethanol solution, the light response range of titanium dioxide is expanded from a single ultraviolet light region to an ultraviolet light region + visible light region, significantly improving the photocatalytic efficiency. Therefore, through modification, the water treatment effect and efficiency are significantly improved, the cleanliness of the water quality is further improved, and a healthy growth environment for shrimp is guaranteed.

[0018] Furthermore, in S1, the coarse filter screen, fiber filter cloth and activated carbon filter layer are backwashed every 5 days, the backwash water pressure is 0.2-0.4 MPa, and the backwash time is 10-20 minutes.

[0019] By adopting the above technical solution, the coarse filter screen, fiber filter cloth and activated carbon filter layer are backwashed regularly to ensure the continuous and effective filtration of the filter material, prevent the accumulation of impurities that affect the filtration effect, and avoid impurities penetrating the filter layer, resulting in the inability of subsequent treatment processes to effectively remove pathogens and biotoxic substances. This ensures the pretreatment quality of the aquaculture water, provides a good foundation for subsequent treatment, and indirectly helps to maintain the high SPF and non-biotoxic state of the entire aquaculture water, ensuring the healthy growth of shrimp.

[0020] Furthermore, the organic chelating agent is one of disodium ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

[0021] By adopting the above technical solution and selecting disodium ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid as an organic chelating agent, harmful substances such as heavy metal ions in the aquaculture water can be effectively chelated, reducing biological toxicity. At the prescribed dosage, no harmful components will remain in the water, thus preventing shrimp from being contaminated by heavy metals, ensuring the safety of the aquaculture water, and reducing the risk of shrimp disease.

[0022] Furthermore, the filter membrane in S2 is a polyvinylidene fluoride filter membrane, and the pore size of the filter membrane is 0.01-0.1 μm.

[0023] Furthermore, during the S3 ultraviolet irradiation treatment, the water is stirred at a stirring speed of 50-150 r / min.

[0024] Furthermore, after the S3 ultraviolet irradiation treatment, the treated water is introduced into a filter column filled with a mixed filter material of quartz sand and activated carbon for re-filtration. The volume ratio of quartz sand to activated carbon is 2:1, and the filtration rate of the filter column is controlled at 5-10m / h.

[0025] Using this technical solution, quartz sand and activated carbon are mixed in a 2:1 volume ratio as the filter media. The larger quartz sand's larger particle size primarily intercepts larger impurities and some residual modified nano-titanium dioxide particles. The activated carbon, with its rich pore structure and high specific surface area, absorbs residual, incompletely degraded organic matter, some heavy metal ions, and other minute impurities in the water. The filter column's filtration rate is controlled at 5-10 m / h, ensuring sufficient contact time between water and the filter media, fully maximizing the filtration and adsorption effects, further purifying the aquaculture water to ensure it meets high-efficiency SPF and non-biotoxic standards, providing high-quality aquaculture water for shrimp.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present application realizes comprehensive purification of aquaculture water by combining physical adsorption with chemical treatment. In step S1, a coarse filter, a fiber filter cloth and an activated carbon filter layer are used in sequence to filter impurities of different particle sizes, adsorb organic matter, heavy metal ions and odors, and remove some impurities that may carry pathogens. In step S2, modified bentonite and an organic chelating agent work synergistically to further adsorb impurities, chelate heavy metals and reduce biological toxicity. In step S3, the active oxygen species produced by modified nano-titanium dioxide under ultraviolet irradiation can effectively kill specific pathogens and degrade organic pollutants. Common pathogens such as white spot disease virus (WSSV) and Vibrio parahaemolyticus (EMS) can be effectively removed, and the final treated water is free of impurities and pathogen residues, providing a high-quality water source without biological toxicity and specific pathogens for the growth of shrimp, greatly reducing the risk of shrimp infection and ensuring the healthy growth of shrimp.

[0028] 2. The modified bentonite in this application is prepared by a specific method, which enhances its adsorption capacity and helps to more effectively remove impurities and pathogens in the water. The preparation process of modified nano-titanium dioxide has also been optimized to improve its photocatalytic and disinfection properties. In addition, the filter material is backwashed regularly in S1 to ensure its continuous and effective filtration; specific organic chelating agents and filter membranes are selected in S2, and measures such as stirring during ultraviolet irradiation and re-filtration after irradiation in S3 further improve the water quality treatment effect. These technical solutions not only improve the quality of aquaculture water and reduce the occurrence of shrimp diseases, but also increase the growth rate and survival rate of shrimp, thereby increasing aquaculture output and improving aquaculture efficiency.

[0029] 3. While achieving efficient SPF treatment and ensuring that aquaculture water is free of biotoxicity, the water treatment method of this application also focuses on environmental protection. On the one hand, it reduces the waste of water resources caused by frequent water changes in traditional aquaculture models, and by recycling aquaculture water, it reduces the demand for new water. On the other hand, it avoids the use of biotoxic chemicals, reducing pollution to water bodies and the surrounding environment. The water treatment method provided by this application has the advantages of being environmentally friendly and efficient, and provides a sustainable development direction for the sustainable development of the aquaculture industry. DETAILED DESCRIPTION

[0030] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0031] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0032] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0033] Example 1

[0034] A water treatment method with high SPF efficiency and no biotoxicity, comprising the following steps:

[0035] S1. Filter the aquaculture water through a coarse filter, a fiber filter cloth, and an activated carbon filter layer in sequence for 2 hours; the pore size of the coarse filter is 5 mm; the pore size of the fiber filter cloth is 0.5 mm; the iodine value of the activated carbon filter layer is 800 mg / g;

[0036] S2, add modified bentonite and organic chelating agent to the filtered aquaculture water and stir to react for 1 hour. The amount of modified bentonite added is 6kg / m 3 , the amount of organic chelating agent added is 1kg / m 3 After the reaction is completed, the solution is allowed to settle for 6 hours and then filtered through a membrane to obtain purified water. The modified bentonite is prepared by adding bentonite to a 2% chitosan solution at a mass ratio of 1:5, stirring at 50°C for 5 hours, and then filtering and drying to obtain the modified bentonite. The organic chelating agent is disodium ethylenediaminetetraacetic acid. The filter membrane is a polyvinylidene fluoride filter membrane with a pore size of 0.01 μm.

[0037] S3, add modified nano titanium dioxide to the purified water, the amount of modified nano titanium dioxide added is 0.5kg / m 3 Then the UV irradiation treatment was carried out, the UV wavelength was 250nm, and the irradiation intensity was 20mW / cm 2, the irradiation time is 1h. During the ultraviolet irradiation treatment, the water is stirred at a stirring speed of 150r / min. After the ultraviolet irradiation treatment, the treated water is introduced into a filter column filled with a mixed filter material of quartz sand and activated carbon for re-filtration. The volume ratio of quartz sand and activated carbon is 2:1, and the filtration speed of the filter column is controlled at 5m / h. The modified nano-titanium dioxide is prepared by the following method: the nano-titanium dioxide is placed in a nitric acid solution with a concentration of 8% and ultrasonically cleaned for 35 minutes at an ultrasonic frequency of 30kHz and an ultrasonic power of 200W, and then vacuum-dried at 55°C for 3h to obtain pretreated nano-titanium dioxide; the pretreated nano-titanium dioxide is placed in a Tris-HCl buffer solution with a pH of 8.5, and dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea are added in sequence and magnetically stirred at 600r / min under a nitrogen atmosphere for 40 minutes. The mass volume of the pretreated nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea, and Tris-HCl buffer solution is 10000rpm. The volume ratio g / L is 1.0:2.0:24:4:1.0, and then 4% ammonia water is added dropwise to adjust the pH to 9.4 and react at 33°C for 2.2h, then the temperature is raised to 43°C, 0.04mol / L ascorbic acid is added, and the reaction is carried out in the dark for 15h, and then the mixture is placed in a tube furnace and a mixture of argon and hydrogen sulfide with a volume ratio of 95:5 is introduced at 5°C / min to 450°C, kept warm for 1.9h, and then naturally cooled to 200°C and quenched with nitrogen to obtain a sulfurized material; the sulfurized material is then placed in a 0.01mol / L terpyridine ruthenium chloride ethanol solution with a solid-liquid ratio g / mL of 1:4, and a 365nm, 10mW / cm 2 The mixture was irradiated with ultraviolet light for 45 minutes, and then centrifuged to obtain the solid matter, which was vacuum dried at 55° C. for 6 hours to obtain modified nano-titanium dioxide.

[0038] Example 2

[0039] A water treatment method with high SPF efficiency and no biotoxicity, comprising the following steps:

[0040] S1. Filter the aquaculture water through a coarse filter, a fiber filter cloth, and an activated carbon filter layer in sequence for 3 hours; the pore size of the coarse filter is 3.5 mm; the pore size of the fiber filter cloth is 0.3 mm; the iodine value of the activated carbon filter layer is 650 mg / g;

[0041] S2, add modified bentonite and organic chelating agent to the filtered aquaculture water and stir to react for 1.5h. The amount of modified bentonite added is 4kg / m 3 , the amount of organic chelating agent added is 0.75kg / m 3After the reaction is completed, the solution is allowed to settle for 5 hours and then filtered through a membrane to obtain purified water. The modified bentonite is prepared by adding bentonite to a 3.5% chitosan solution at a mass ratio of 1:7.5, stirring at 60°C for 4 hours, and then filtering and drying to obtain the modified bentonite. The organic chelating agent is disodium ethylenediaminetetraacetic acid. The filter membrane is a polyvinylidene fluoride filter membrane with a pore size of 0.05 μm.

[0042] S3, add modified nano titanium dioxide to the purified water, the amount of modified nano titanium dioxide added is 0.3kg / m 3 Then the UV irradiation treatment was carried out with a wavelength of 400 nm and an irradiation intensity of 15 mW / cm 2 , the irradiation time is 1.5h. During the ultraviolet irradiation treatment, the water is stirred at a stirring speed of 100r / min. After the ultraviolet irradiation treatment, the treated water is introduced into a filter column filled with a mixed filter material of quartz sand and activated carbon for re-filtration. The volume ratio of quartz sand and activated carbon is 2:1, and the filtration speed of the filter column is controlled at 7.5m / h. The modified nano-titanium dioxide is prepared by the following method: the nano-titanium dioxide is placed in a nitric acid solution with a concentration of 10% and ultrasonically cleaned for 30 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power of 300W, and then vacuum-dried at 60°C for 2.5h to obtain pretreated nano-titanium dioxide; the pretreated nano-titanium dioxide is placed in a Tris-HCl buffer solution with a pH of 8.7, and dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea are added in sequence and magnetically stirred at 800r / min under a nitrogen atmosphere for 35 minutes. The mass volume of the pretreated nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea, and Tris-HCl buffer solution is 1:1. The ratio g / L is 1.2:2.2:30:5:1.0, and then 5% ammonia water is added dropwise to adjust the pH to 9.5 and react at 35°C for 2.0h, then the temperature is raised to 45°C, 0.05mol / L ascorbic acid is added, and the reaction is carried out in the dark for 12.5h, and then the mixture is placed in a tube furnace and a mixture of argon and hydrogen sulfide with a volume ratio of 95:5 is introduced at 8°C / min to 450°C, and the mixture is kept warm for 2.0h, and then the temperature is naturally lowered to 200°C and quenched with nitrogen to obtain a sulfurized material; the sulfurized material is then placed in a 0.02mol / L terpyridine ruthenium chloride ethanol solution with a solid-liquid ratio g / mL of 1:5, and a 365nm, 12.5mW / cm 2 The mixture was irradiated with ultraviolet light for 40 minutes, and then centrifuged to obtain the solid matter, which was vacuum dried at 60° C. for 5 hours to obtain modified nano-titanium dioxide.

[0043] Example 3

[0044] A water treatment method with high SPF efficiency and no biotoxicity, comprising the following steps:

[0045] S1. Filter the aquaculture water through a coarse filter, a fiber filter cloth, and an activated carbon filter layer in sequence for 4 hours; the pore size of the coarse filter is 2 mm; the pore size of the fiber filter cloth is 0.1 mm; the iodine value of the activated carbon filter layer is 500 mg / g;

[0046] S2, add modified bentonite and organic chelating agent to the filtered aquaculture water and stir to react for 2h. The amount of modified bentonite added is 2kg / m 3 , the amount of organic chelating agent added is 0.5kg / m 3 After the reaction is completed, the solution is allowed to settle for 4 hours and then filtered through a membrane to obtain purified water. The modified bentonite is prepared by adding bentonite to a 5% chitosan solution at a mass ratio of 1:10, stirring at 70°C for 3 hours, filtering, and drying to obtain the modified bentonite. The organic chelating agent is diethylenetriaminepentaacetic acid. The filter membrane is a polyvinylidene fluoride filter membrane with a pore size of 0.1 μm.

[0047] S3, add modified nano titanium dioxide to the purified water, the amount of modified nano titanium dioxide added is 0.2kg / m 3 Then the UV irradiation treatment was carried out with a wavelength of 550nm and an irradiation intensity of 10mW / cm 2, the irradiation time is 2h. During the ultraviolet irradiation treatment, the water is stirred at a stirring speed of 50r / min. After the ultraviolet irradiation treatment, the treated water is introduced into a filter column filled with a mixed filter material of quartz sand and activated carbon for re-filtration. The volume ratio of quartz sand and activated carbon is 2:1, and the filtration speed of the filter column is controlled at 10m / h. The modified nano-titanium dioxide is prepared by the following method: the nano-titanium dioxide is placed in a nitric acid solution with a concentration of 12% and ultrasonically cleaned for 255min at an ultrasonic frequency of 50kHz and an ultrasonic power of 400W, and then vacuum-dried at 65°C for 2h to obtain pretreated nano-titanium dioxide; the pretreated nano-titanium dioxide is placed in a Tris-HCl buffer solution with a pH of 9.0, and dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea are added in sequence and magnetically stirred at 1000r / min for 30min under a nitrogen atmosphere. The mass of the pretreated nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea, and Tris-HCl buffer solution is 1000r / min. The volume ratio g / L is 1.5:2.5:36:6:1.0, and then 6% ammonia water is added dropwise to adjust the pH to 9.6 and react at 37°C for 1.8h, then the temperature is raised to 47°C, 0.06mol / L ascorbic acid is added, and the reaction is carried out in the dark for 10h, and then the mixture is placed in a tube furnace and a mixture of argon and hydrogen sulfide with a volume ratio of 95:5 is introduced at 10°C / min to 450°C, kept warm for 2.1h, and then naturally cooled to 200°C and quenched with nitrogen to obtain a sulfurized material; the sulfurized material is then placed in a 0.02mol / L terpyridine ruthenium chloride ethanol solution with a solid-liquid ratio g / mL of 1:6, and a 365nm, 15mW / cm 2 The mixture was irradiated with ultraviolet light for 35 minutes, and then centrifuged to obtain the solid matter, which was vacuum dried at 65° C. for 4 hours to obtain modified nano-titanium dioxide.

[0048] Comparative Example 1

[0049] This comparative example is compared with Example 2, except that an equal amount of unmodified bentonite is used instead of modified bentonite in step S2.

[0050] Comparative Example 2

[0051] Compared with Example 2, this comparative example differs in that an equal amount of unmodified nano-titanium dioxide is used instead of modified nano-titanium dioxide in step S3.

[0052] Comparative Example 3

[0053] Compared with Example 2, the difference between this comparative example and Example 2 is that, when preparing the modified nano-titanium dioxide in step S3, no terpyridine ruthenium chloride ethanol solution is used for soaking, and the modified nano-titanium dioxide is prepared by the following method: the nano-titanium dioxide is placed in a nitric acid solution with a concentration of 10% and ultrasonically cleaned for 30 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power of 300W, and then vacuum-dried at 60°C for 2.5 hours to obtain pretreated nano-titanium dioxide; the pretreated nano-titanium dioxide is placed in a Tris-HCl buffer solution with a pH of 8.7, dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea are added in sequence, and magnetic stirring is carried out at 800r / min under a nitrogen atmosphere for 35 minutes to pre-treat the nano-titanium dioxide. The mass volume ratio of nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea and Tris-HCl buffer is 1.2:2.2:30:5:1.0 g / L, and then 5% ammonia water is added dropwise to adjust the pH to 9.5 and react at 35°C for 2.0h, then the temperature is raised to 45°C, 0.05mol / L ascorbic acid is added, and the mixture is reacted in the dark for 12.5h, then placed in a tube furnace, and a mixture of argon and hydrogen sulfide with a volume ratio of 95:5 is introduced at a rate of 8°C / min to 450°C, and the temperature is kept for 2.0h. Then the temperature is naturally lowered to 200°C and quenched with nitrogen to obtain a vulcanized material; the vulcanized material is then vacuum dried at 60°C for 5h to obtain modified nano-titanium dioxide.

[0054] Performance testing

[0055] Test object: aquaculture water treated in Examples 1-3 and Comparative Examples 1-3.

[0056] 1. Heavy metal content detection

[0057] Inductively coupled plasma mass spectrometry was used for detection. The aquaculture water treated in Examples 1-3 and Comparative Examples 1-3 was introduced as samples into an inductively coupled plasma mass spectrometer. Instrumental analysis revealed the total content of heavy metal elements, such as lead, mercury, cadmium, and chromium, in the water. Three tests were performed for each, and the average values were taken. The results are shown in Table 1.

[0058] 2. Ammonia nitrogen content detection

[0059] Nessler's reagent spectrophotometry was used for detection. Nessler's reagent was added to the treated aquaculture water samples from Examples 1-3 and Comparative Examples 1-3, respectively. Ammonia nitrogen reacted with the Nessler's reagent to form a light reddish-brown colloidal compound whose absorbance was proportional to the ammonia nitrogen content. The absorbance was measured at a wavelength of 420 nm, and the ammonia nitrogen content was calculated using a standard curve. Three measurements were performed, and the average values were calculated. The results are shown in Table 1.

[0060] 3. Pathogen content detection

[0061] The treated aquaculture water samples of Examples 1-3 and Comparative Examples 1-3 were inoculated onto nutrient agar and Vibrio selective media, respectively. After incubation at 28°C for 36 hours, the colonies grown on the culture medium were counted to obtain the total bacterial count and Vibrio count. White spot disease virus (WSSV) and Vibrio parahaemolyticus (EMS) were detected using polymerase chain reaction (PCR). The results are shown in Table 1.

[0062] Table 1 Test results of aquaculture water after treatment of Examples 1-3 and Comparative Examples 1-3

[0063]

[0064] In this application, bentonite is modified by using chitosan. The amino and hydroxyl groups in the chitosan molecules form stable chelate bonds with heavy metals, and the protonated amino groups of chitosan can also adsorb anionic heavy metals through electrostatic attraction. In addition, the interlayer domain of bentonite is loaded with chitosan to form a three-dimensional network structure, and the specific surface area is significantly improved, thereby significantly increasing the density of adsorption sites. At the same time, the linear molecular chains of chitosan are interspersed between the bentonite layers to form a "molecular sieve" effect, selectively adsorbing heavy metal ions of a specific particle size. The synergistic effect of the above mechanisms significantly improves the removal effect of heavy metals. The protonation of chitosan amino groups and NH4 + Competing for Na on the bentonite surface + / Ca 2+ sites to achieve ion exchange. And the hydroxyl groups of chitosan and NH4 + Form intermolecular hydrogen bonds and enhance adsorption stability. Modified bentonite forms larger flocs after combining with ammonia nitrogen, which settle quickly during static sedimentation, thereby avoiding the suspended solids residue caused by fine particles of unmodified bentonite. Through the above effects, ammonia nitrogen in water bodies is effectively removed. By coating bentonite with modified chitosan, the surface positive charge is enhanced, and strong electrostatic adsorption is produced on the negatively charged bacterial cell membrane. Chitosan can also penetrate the cell wall of pathogens, bind to DNA, and inhibit mRNA synthesis, leading to cell lysis. In addition, chitosan can also bind to viral capsid proteins, destroying their structural integrity and inactivating viral particles. The present application realizes adsorption-chelation-antibacterial integration by modifying bentonite, achieving "capture-inactivation" synchronization, and its purification effect is significantly improved compared to the unmodified bentonite used in step S2 of Comparative Example 1.

[0065] The modification treatment in this application causes the absorption edge of modified nano-titanium dioxide to red-shift to the visible light region, stimulating more electron-hole pairs under ultraviolet and visible light. The electrons reduce the high-valent heavy metal ions to low-toxic or precipitated states, while the holes oxidize water to generate hydroxyl radicals, which further oxidize heavy metals. The zinc sulfide formed in the sulfur doping process of this application forms a heterojunction with titanium dioxide, and the sulfur-rich surface of zinc sulfide and Hg 2+ 、Cd2+ etc. to form a strong coordination complex, and the adsorption capacity is significantly improved. In this application, a polydopamine layer is deposited on the surface of nano-titanium dioxide through modification, and the polydopamine layer adsorbs soluble organic matter, reducing its competition with ammonia nitrogen for active sites, thereby effectively removing ammonia nitrogen. Titanium dioxide is excited to produce reactive oxygen species such as hydroxyl radicals and hydrogen peroxide, which destroy bacterial cell membrane lipids and viral capsid proteins. The sulfide titanium dioxide obtained by sulfur doping treatment in the modification process of this application produces a mild thermal effect under light, which accelerates the denaturation of pathogen proteins and further enhances the removal effect of pathogens. By placing it in a terpyridine ruthenium chloride ethanol solution, the light response range of titanium dioxide is expanded from a single ultraviolet light region to an ultraviolet light region + visible light region, significantly improving the photocatalytic efficiency. Therefore, through modification, the water treatment effect and efficiency are significantly improved.

[0066] The present invention places the sulfurized material in a terpyridine ruthenium chloride ethanol solution and applies ultraviolet light irradiation. The ultraviolet light excites titanium dioxide to generate electrons, driving Ru 3+ Reduction and anchoring to the polydopamine layer to form a stable chemical bond, achieving efficient loading of ruthenium complexes. Ru(bpy)3 2+ The metal-ligand charge transfer absorption band expands the light response range of titanium dioxide from a single ultraviolet region to the ultraviolet region + visible light region, and the photogenerated electrons promote Ru 3+ Reduction to Ru 2+ and Ti produced by sulfur doping 3+ Defect sites form a [Ru(II)-Ti(III)] charge transfer complex. This complex can store electrons and release them through dark state electrons after the light stops, continuously reducing pollutants and achieving photocatalysis without light, breaking through the limitation of traditional photocatalysts that rely on continuous light. 2+ The sustained release can also interfere with the activity of pathogen enzymes and, combined with the destruction of the biofilm matrix by reactive oxygen species, reduce the amount of biofilm formed. The amino groups in the polydopamine layer are protonated under acidic conditions and preferentially adsorb anionic pollutants through electrostatic attraction; while under alkaline conditions, the amino groups are deprotonated to form dynamic ion pairs with the negatively charged ligands of the Ru complex, promoting the directional oxidation of NH3 to N2 by holes, achieving dynamic changes in the surface charge of the material with pH, and thus realizing intelligent switching of pollutant adsorption-oxidation pathways. This modification scheme, through multi-level photo-electro-chemical synergy, gives the material a wide spectral response, long-lasting catalysis, and environmental adaptability, and its overall performance is significantly improved compared to unmodified nano-titanium dioxide.

[0067] 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 in the scope of protection of the present invention.

Claims

1. A water treatment method with high SPF and no biotoxicity, characterized in that: The following steps are involved: S1. Filter the aquaculture water through a coarse filter, a fiber filter cloth, and an activated carbon filter layer in sequence for 2-4 hours; the pore size of the coarse filter is 2-5 mm; the pore size of the fiber filter cloth is 0.1-0.5 mm; and the iodine value of the activated carbon filter layer is 500-800 mg / g; S2, adding modified bentonite and an organic chelating agent to the filtered aquaculture water and stirring the reaction for 1-2 hours, the modified bentonite addition amount is 2-6 kg / m3, and the organic chelating agent addition amount is 0.5-1.0 kg / m3; after the reaction is completed, the reaction is allowed to settle for 4-6 hours, and purified water is obtained after filtering through a filter membrane; S3, add modified nano titanium dioxide to the purified water, the amount of modified nano titanium dioxide added is 0.2-0.5kg / m3; then perform ultraviolet irradiation treatment, the ultraviolet wavelength is 250-550nm, the irradiation intensity is 10-20mW / cm 2 The irradiation time is 1-2h, and the filtration is carried out after ultraviolet irradiation treatment.

2. A water treatment method with high SPF and no biotoxicity according to claim 1, characterized in that: The modified bentonite is prepared by the following method: adding bentonite to a chitosan solution with a mass fraction of 2-5%, with the mass ratio of bentonite to chitosan solution being 1:(5-10), stirring and reacting at 50-70°C for 3-5h, and after the reaction is completed, filtering and drying to obtain the modified bentonite.

3. The water treatment method of claim 1, wherein the water treatment method comprises: The modified nano-titanium dioxide is prepared by the following method: placing the nano-titanium dioxide in a nitric acid solution with a concentration of 8-12%, and ultrasonically cleaning it for 25-35 minutes under the conditions of an ultrasonic frequency of 30-50kHz and an ultrasonic power of 200-400W, and then vacuum drying it at 55-65°C for 2-3 hours to obtain pretreated nano-titanium dioxide; placing the pretreated nano-titanium dioxide in a Tris-HCl buffer solution, adding dopamine hydrochloride, zinc nitrate hexahydrate, and thiourea in sequence, and magnetically stirring the solution under a nitrogen atmosphere; then dropping ammonia water with a concentration of 4-6% to adjust the pH to 9.4-9.6, and evaporating the solution at 3°C. The reaction was carried out at 3-37°C for 1.8-2.2 hours, and then the temperature was raised to 43-47°C, 0.04-0.06 mol / L ascorbic acid was added, and the mixture was protected from light for 10-15 hours. The mixture was then placed in a tube furnace, and a mixture of argon and hydrogen sulfide was introduced at a rate of 5-10°C / min to 450°C, and the mixture was kept warm for 1.9-2.1 hours. The mixture was then naturally cooled to 200°C and quenched with nitrogen to obtain a sulfurized material. The sulfurized material was then placed in a 0.01-0.02 mol / L terpyridine ruthenium chloride ethanol solution at a solid-liquid ratio of g / mL of 1:(4-6), and a wavelength of 365 nm and 10-15 mW / cm was applied. 2 The mixture was irradiated with ultraviolet light for 35-45 minutes, and then centrifuged to obtain the solid matter, which was vacuum dried at 55-65° C. for 4-6 hours to obtain modified nano-titanium dioxide.

4. The water treatment method according to claim 1, wherein: The mass volume ratio of pretreated nano-titanium dioxide, dopamine hydrochloride, zinc nitrate hexahydrate, thiourea, and Tris-HCl buffer is (1.0-1.5):(2.0-2.5):(24-36):(4-6):1.0 g / L, and magnetic stirring is carried out at 600-1000 r / min for 30-40 min. The pH value of the Tris-HCl buffer is 8.5-9.0, and the volume ratio of argon to hydrogen sulfide in the argon and hydrogen sulfide mixture is 95:

5.

5. The water treatment method of claim 1, wherein the water treatment method has high SPF and no biological toxicity. In the S1, the coarse filter screen, the fiber filter cloth and the activated carbon filter layer are backwashed every 5 days, the backwash water pressure is 0.2-0.4 MPa, and the backwash time is 10-20 minutes.

6. The water treatment method of claim 1, wherein: The organic chelating agent is one of disodium ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

7. A water treatment method with high SPF efficiency and no biotoxicity according to claim 6, characterized in that: The filter membrane in S2 is a polyvinylidene fluoride filter membrane, and the pore size of the filter membrane is 0.01-0.1 μm.

8. A water treatment method with high SPF efficiency and no biotoxicity according to claim 7, characterized in that: During the S3 ultraviolet irradiation treatment process, the water is stirred at a stirring speed of 50-150 r / min.

9. The water treatment method of claim 1, wherein: After S3 ultraviolet irradiation treatment, the treated water is introduced into a filter column filled with a mixed filter material of quartz sand and activated carbon for re-filtration. The volume ratio of quartz sand and activated carbon is 2:1, and the filtration rate of the filter column is controlled at 5-10m / h.

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