Water quality improver for aquaculture and preparation method thereof

Abstract

The invention discloses a water quality improver for aquaculture and a preparation method thereof, and belongs to the technical field of water quality improvement, walnut shell derivatives are subjected to acid pickling and calcination to obtain pretreated biochar, titanium dioxide / iron-manganese nanosheets are loaded to obtain composite biochar, composite bacteria are coated with sodium alginate-calcium chloride to form core-shell microspheres, and the core-shell microspheres are subjected to ball milling to obtain the water quality improver for aquaculture. Adding gelatin-tannic acid hydrogel to realize slow release, so as to obtain antibacterial composite hydrogel; the preparation method comprises the following steps: carrying out ball milling on composite biochar, bentonite, deionized water and hollow glass beads to obtain a main material, homogenizing and emulsifying cod liver oil and antibacterial composite hydrogel to obtain an auxiliary material, and processing by a pelleting machine to obtain the water quality improver for aquaculture. The three functions of adsorption, photocatalytic degradation and biological antibiosis are synergistically realized, and the removal rate of organic matters and the stability of water quality are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality improvement, and particularly relates to an aquaculture water quality improver and a preparation method thereof. Background Art

[0002] With the advancement of aquaculture technology, high-density aquaculture has become an industry trend, resulting in the pond's self-purification capacity being insufficient to remove pollutants such as leftover bait, fish and shrimp feces, causing ammonia nitrogen, nitrite, sulfide and other levels in the aquaculture water to seriously exceed the standard, pond water quality to deteriorate, and fish and shrimp diseases to occur frequently. In order to solve the problem of water quality deterioration caused by high-density aquaculture, it is necessary to develop a new type of water quality improver for aquaculture to achieve high-efficiency and low-cost purification of aquaculture water.

[0003] Water quality improvers refer to substances or methods used to improve water quality. Water quality improvement can be achieved by adding specific chemicals or adopting specific treatment methods. Water quality improvers for aquaculture refer to a class of chemical substances or biological agents used to improve and optimize the aquaculture water environment. They are usually intended to regulate the physical, chemical and biological properties of the water body to create an environment more suitable for the survival and growth of farmed species. They can be divided into two major categories: physical and chemical. Chemical water quality improvers are mainly strong oxidant-type chemical disinfectants, such as sodium percarbonate, potassium permonosulfate complex salt and calcium peroxide. This type of improver can not only improve the water quality environment, the bottom quality of the water body, and enhance the strong oxygenation of the water body, but also disinfect, sterilize, detoxify and inhibit bacteria.

[0004] A Chinese invention patent application with publication number CN 117446886A discloses a water quality improver for aquatic products and a preparation method thereof. The improver reacts with active amino groups and hydroxyl groups to undergo a hydroxylation reaction, and simultaneously reacts with nano-silver-coated zinc oxide to produce a synergistic effect, thereby achieving stronger adsorption performance and flocculation effect. A bridging reaction occurs between copper sulfate and yeast, giving it stronger adsorption performance and flocculation effect. The yeast can produce biologically active substances through its own metabolism to achieve sterilization.

[0005] Among them, nanosilver-coated zinc oxide is used as an antibacterial component, but nanosilver is easily enriched in the gills, liver and other organs of aquatic organisms. Long-term use may lead to chronic poisoning or food chain transmission risks, especially it has a non-selective killing effect on phytoplankton and probiotics, which may destroy the ecological balance of the water body. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of ecotoxicity and environmental pollution caused by the use of high-risk antibacterial components (such as nanosilver) in traditional water quality improvers, while improving the sustainability and safety of the water quality improvement effect, and to provide a water quality improver for aquaculture and a preparation method thereof.

[0007] The invention prepares pretreated biochar by acid-washing and calcining walnut shell derivatives, loading titanium dioxide / iron-manganese nanosheets to obtain composite biochar, then coating the composite bacterial community with sodium alginate-calcium chloride to form core-shell microspheres, and then adding gelatin-tannic acid hydrogel to achieve sustained release to obtain an antibacterial composite hydrogel; the composite biochar, bentonite, deionized water and hollow glass microbeads are ball-milled to obtain a main ingredient, and cod liver oil and the antibacterial composite hydrogel are homogenized and emulsified to obtain an auxiliary material, which is then processed by a pellet press to obtain a water quality improver for aquaculture.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A water quality improver for aquaculture, comprising the following components and raw materials, calculated by weight: 40-50 parts of composite biochar, 8-10 parts of bentonite, 50-60 parts of deionized water, 8-10 parts of hollow glass microspheres, 16-20 parts of cod liver oil and 35-40 parts of antibacterial composite hydrogel; The composite biochar is prepared by combining walnut shell derivatives and titanium dioxide / iron-manganese nanosheets; Titanium dioxide / iron-manganese nanosheets are prepared by the following steps: Ferric chloride hexahydrate, manganese sulfate and deionized water are stirred to obtain a mixed metal solution; anatase nano-titanium dioxide, deionized water, the mixed metal solution, 1wt% sodium citrate solution and 1wt% ascorbic acid solution are stirred under nitrogen in the dark, and ultraviolet light is used for catalytic reduction deposition to obtain titanium dioxide / iron-manganese nanosheets.

[0009] Furthermore, the composite biochar is prepared by the following steps: The walnut shell derivative is acid-washed and refluxed for 1-2 hours, washed with ultrapure water until neutral, filtered, dried, and calcined at 400-500°C under nitrogen protection for 2-3 hours to obtain pretreated biochar; titanium dioxide / iron-manganese nanosheets, pretreated biochar and deionized water are added to a reactor, stirred at 300-400 rpm for 2-3 hours, transferred to a 500 mL polytetrafluoroethylene-lined stainless steel reactor, reacted at 160-180°C for 6-8 hours, cooled to room temperature, filtered, vacuum dried at 70-80°C to constant weight, ground, and passed through a 100-mesh sieve to obtain composite biochar.

[0010] Furthermore, the dosage ratio of titanium dioxide / iron-manganese nanosheets, pretreated biochar and deionized water is 9-15 g: 1-3 g: 240-300 mL.

[0011] Furthermore, the titanium dioxide / iron-manganese nanosheets are specifically prepared by the following steps: Ferric chloride hexahydrate, manganese sulfate and deionized water are added to a reactor and stirred at 60-70°C for 10-15 minutes to obtain a mixed metal solution; anatase nano-titanium dioxide and deionized water are added to the reactor, ultrasonicated for 20-30 minutes, and then the mixed metal solution, 1wt% sodium citrate solution and 1wt% ascorbic acid solution are added, nitrogen is introduced for 20-30 minutes, and the mixture is stirred at 300-350rpm in a light-shielded manner for 20-30 minutes. The bottom of a 365nm ultraviolet lamp is placed 5-10 cm above the liquid surface, the light is turned on, and the mixture is reacted in a water bath at 40-50°C for 3-4 hours. The suspension turns brown-black, is filtered, and repeatedly washed with 1wt% sodium citrate solution and nitrogen-saturated ethanol until the water is clear, and then vacuum dried to constant weight to obtain titanium dioxide / iron-manganese nanosheets.

[0012] Furthermore, the usage ratio of ferric chloride hexahydrate, manganese sulfate and deionized water is 4.5-5.5 g:4.5-5.5 g:90-100 mL; The dosage ratio of anatase nano-titanium dioxide, deionized water, mixed metal solution, sodium citrate solution and ascorbic acid solution is 9.0-11.0 g: 0.9-1.0 L: 45-55 mL: 90-100 mL: 450-550 mL.

[0013] Furthermore, the antibacterial composite hydrogel is prepared by the following steps: The composite bacterial liquid is added to the reactor, centrifuged for 10-15 minutes, the bacteria are collected, transferred to phosphate buffer and 4wt% sodium alginate solution, stirred for 20-30 minutes, and then 0.1wt% calcium chloride solution is added dropwise and solidified for 20-30 minutes to obtain core-shell antibacterial microspheres; gelatin and deionized water are added to the reactor, stirred at 50-60°C for 20-30 minutes, tannic acid is added, the pH value is adjusted to 8 with sodium hydroxide, stirred for 10-15 minutes, and then the core-shell antibacterial microspheres are added, stirred for 5-10 minutes, poured into a mold, frozen at -30°C to -20°C for 1-2 hours, and thawed at room temperature to obtain an antibacterial composite hydrogel.

[0014] Furthermore, the usage ratio of the composite bacterial solution, phosphate buffer, sodium alginate solution and calcium chloride solution is 20-30 mL: 5-10 mL: 10-15 mL: 0.8-1.0 mL; The usage ratio of gelatin, deionized water, tannic acid and core-shell antibacterial microspheres is 3.0-3.5 g: 30-40 mL: 0.5-1.0 g: 0.5-1.0 g.

[0015] Furthermore, the composite bacterial solution is prepared by the following steps: 1.5wt% shrimp shell hydrolyzate, 0.3wt% fish meal peptone, 0.04wt% sodium nitrate and 0.1wt% riboflavin solution are added to a reactor, and the pH value is adjusted to 6 with deionized water to obtain a composite bacterial culture medium; a Bacillus licheniformis suspension, a Bacillus subtilis suspension, a Rhodopseudomonas palustris suspension, a Rhodobacter sphaeroides suspension and an enzyme-producing Bacillus lysogenus suspension are inoculated into the composite bacterial culture medium, and the mixture is cultured at 30-40°C for 100-120 hours to obtain a composite bacterial liquid.

[0016] Furthermore, the mass ratio of shrimp shell hydrolyzate, fish meal peptone, sodium nitrate and riboflavin is 3-5:0.6-0.8:0.08-0.1:0.2-0.4; The dosage ratio of Bacillus licheniformis suspension, Bacillus subtilis suspension, Rhodopseudomonas palustris suspension, Rhodobacter sphaeroides suspension, enzyme-producing lysobacter suspension and composite bacterial culture medium is 1.8-2.2mL: 1.8-2.2mL: 2.4-3.0mL: 3.0-3.6mL: 1.0-1.5mL: 200-300g.

[0017] Furthermore, a method for preparing a water quality improver for aquaculture comprises the following steps: Step 1: Add composite biochar, bentonite and deionized water into a ball mill, and ball mill for 20-30 minutes, then add hollow glass microbeads and ball mill for 10-20 minutes to obtain the main material; add cod liver oil and antibacterial composite hydrogel into an emulsifier, homogenize and emulsify for 10-15 minutes to obtain the auxiliary material; Step 2: Close the glue outlets on both sides of the fully automatic pill press, preheat the glue outlets to 30-40°C, connect the rubber hose and the air pipe, transport the main material into the gelatin box, open the glue outlet to form a continuous gelatin tape, add the auxiliary material when the tape passes through the rotating mold, press the mold to form an elliptical capsule, dry it at 30-40°C for 2-3h, spray 10wt% citric acid ethanol solution for 10-15s, and vacuum dry to obtain a water quality improver for aquaculture.

[0018] The method of using water quality improver for aquaculture includes the following steps: For open ponds, use 200g / mu·m water quality improver, and for circulating water systems, add 50g / m 3 , cage culture according to 100g / bag (net bag: 40×60cm) per 10m 3 Hang 1 bag; before use, press 1g of improver: 10mL of water, stir for 10-20 minutes, and activate it. After activation, evenly sprinkle it against the wind in the open-air pond, inject it into the circulating water system in proportion, and hang the cage at a water depth of 1.5-3m. Oxygenation must be synchronized throughout the addition process to promote the release of active substances through water flow.

[0019] Beneficial effects of the present invention: 1. The present invention obtains pretreated biochar by acid washing and calcining walnut shell derivatives, and loads titanium dioxide / iron-manganese nanosheets to obtain composite biochar. The composite biochar combines the adsorption effect of biochar and the photocatalytic effect of titanium dioxide / iron-manganese nanosheets to form a multifunctional composite material; the antibacterial composite hydrogel embeds probiotic core-shell microspheres into gelatin-tannic acid hydrogel to achieve sustained-release protection of probiotics and physical barrier antibacterial properties; the "adsorption-photocatalytic degradation-biological antibacterial" trinity is synergistically achieved, significantly improving the organic matter removal rate and water quality stability.

[0020] 2. The titanium dioxide / iron-manganese nanosheets in the present invention utilize iron and manganese doping to broaden the spectrum of titanium dioxide, improve light energy utilization, and efficiently degrade organic pollutants. Iron and manganese oxides specifically remove heavy metals such as lead and cadmium through complex adsorption and redox reactions, and reduce highly toxic chromium to a low-toxic form. After settling in the water body, it oxidizes organic matter in the sediment, inhibits hydrogen sulfide production, and synergizes with probiotics to repair the microecology.

[0021] 3. The composite biochar in the present invention is made of acid-washed and calcined walnut shells to form ultra-porous pores, which can strongly capture ammonia nitrogen and heavy metals. The loaded titanium dioxide / iron-manganese nanosheets stimulate active oxygen under visible light, degrade and adsorb pollutants in situ, and improve the renewable efficiency of the material; the surface functional groups and nanogaps provide a highly stable load for probiotics.

[0022] 4. The antibacterial composite hydrogel of the present invention embeds probiotics in sodium alginate / calcium chloride to obtain core-shell microspheres, which can resist processing and water impact. The gelatin-tannic acid hydrogel network slowly releases bacteria to maintain the activity of functional bacteria. Multiple probiotics can degrade pollutants and inhibit pathogens, and tannic acid can chemically destroy the membrane structure of pathogenic microorganisms, simultaneously solving the needs of organic matter decomposition, ammonia nitrogen conversion and disease prevention and control. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1: A water quality improver for aquaculture, comprising the following components in parts by mass: 40 parts of composite biochar, 8 parts of bentonite, 50 parts of deionized water, 8 parts of hollow glass microspheres, 16 parts of cod liver oil and 35 parts of antibacterial composite hydrogel.

[0025] The preparation method of the water quality improver for aquaculture comprises the following steps: Step 1: Add composite biochar, bentonite and deionized water into a ball mill and mill for 20 minutes, then add hollow glass microbeads and mill for 10 minutes to obtain the main material; add cod liver oil and antibacterial composite hydrogel into an emulsifier and homogenize and emulsify for 10 minutes to obtain the auxiliary material; Step 2: Close the glue outlet on both sides of the fully automatic pill press, preheat the glue outlet to 30°C, connect the rubber hose and the air pipe, transport the main material into the gelatin box, open the glue outlet to form a continuous gelatin tape, add the auxiliary material when the tape passes through the rotating mold, press the mold to form an elliptical capsule, dry it at 30°C for 2h, spray 10wt% citric acid ethanol solution for 10s, and vacuum dry to obtain a water quality improver for aquaculture.

[0026] Through gradient density encapsulation, hollow glass microbeads adjust the density to suspend the water quality improver in the water body, low-temperature pelleting ensures the bacterial community and citric acid cross-linked gelatin, and the outer layer of composite biochar quickly adsorbs and degrades ammonia nitrogen and heavy metals, the middle layer of bentonite buffers salinity mutations, and the core hydrogel slowly releases the bacterial community to prolong the use effect; achieving high purification and long-term antibacterial effect.

[0027] Specifically, the composite biochar is prepared by the following steps: The walnut shell derivative was refluxed in 6wt% hydrochloric acid for 1h, washed with ultrapure water until neutral, filtered, dried, and calcined at 400℃ under nitrogen protection for 2h to obtain pretreated biochar; 9g titanium dioxide / iron-manganese nanosheets, 1g pretreated biochar and 240mL deionized water were added to the reactor, stirred at 300rpm for 2h, transferred to a 500mL stainless steel reactor lined with polytetrafluoroethylene, reacted at 160℃ for 6h, cooled to room temperature, filtered, vacuum dried at 70℃ to constant weight, ground, and passed through a 100-mesh sieve to obtain composite biochar.

[0028] Composite biochar was prepared by acid washing to remove biochar impurities, nitrogen calcination to retain functional groups, and hydrothermal bonding to construct a Ti-OC chemical interface; the specific surface area was increased, the Ti-OC bonds formed electron high-speed channels, and the mesopores could protect the active components of iron / manganese, further improving the photocatalytic degradation rate of ammonia nitrogen and the heavy metal adsorption capacity.

[0029] Specifically, titanium dioxide / iron-manganese nanosheets are prepared by the following steps: 4.5 g of ferric chloride hexahydrate, 4.5 g of manganese sulfate and 90 mL of deionized water were added to a reactor and stirred at 60 ° C for 10 minutes to obtain a mixed metal solution; 9.0 g of anatase nano-titanium dioxide and 0.9 L of deionized water were added to the reactor, ultrasonicated for 20 minutes, and then 45 mL of the mixed metal solution, 90 mL of 1 wt% sodium citrate solution and 450 mL of 1 wt% ascorbic acid solution were added, nitrogen was introduced for 20 minutes, and the mixture was stirred at 300 rpm in a light-shielded state for 20 minutes. The bottom of a 365 nm ultraviolet lamp was placed 5 cm above the liquid surface, the light was turned on, and the mixture was reacted in a 40 ° C water bath for 3 hours. The suspension turned brown-black, was filtered, and washed repeatedly with 1 wt% sodium citrate solution and nitrogen-saturated ethanol until the water was clear, and vacuum dried to constant weight to obtain titanium dioxide / iron-manganese nanosheets.

[0030] Through ultraviolet light catalytic reduction deposition emitted by ultraviolet lamp, ultraviolet light is used to excite anatase titanium dioxide to produce electron-hole pairs under nitrogen protection. Under the directional regulation of sodium citrate and the synergistic reduction effect of ascorbic acid, iron ions and manganese ions are co-deposited on the surface of titanium dioxide to form titanium dioxide / iron-manganese nanosheets; the visible light absorption rate and heavy metal adsorption effect are improved, and the degradation of ammonia nitrogen is prolonged.

[0031] Specifically, the antibacterial composite hydrogel is prepared by the following steps: 20 mL of composite bacterial liquid was added to the reactor, centrifuged for 10 minutes, the bacteria were collected, transferred to 5 mL of phosphate buffer and 10 mL of 4 wt% sodium alginate solution, stirred for 20 minutes, and then 0.8 mL of 0.1 wt% calcium chloride solution was added dropwise and solidified for 20 minutes to obtain core-shell antibacterial microspheres; 3.0 g of gelatin and 30 mL of deionized water were added to the reactor, stirred at 50 ° C for 20 minutes, 0.5 g of tannic acid was added, the pH value was adjusted to 8 with sodium hydroxide, stirred for 10 minutes, and then 0.5 g of core-shell antibacterial microspheres was added, stirred for 5 minutes, poured into a mold and frozen at -30 ° C for 1 hour, and thawed at room temperature to obtain an antibacterial composite hydrogel.

[0032] By preparing core-shell antibacterial microspheres and double encapsulation, calcium alginate-encapsulated bacteria, tannic acid and gelatin form an internal bacterial protection and external bactericidal effect, physically isolating probiotics from antibacterial agents, and replacing nanometals with fully bio-based materials, the problems of heavy metal toxicity and microbial resistance in the comparative patents are solved, achieving long-term ecological and safe water quality improvement.

[0033] Specifically, the composite bacterial solution is prepared by the following steps: 3 g of 1.5 wt% shrimp shell hydrolyzate, 0.6 g of 0.3 wt% fish meal peptone, 0.08 g of 0.04 wt% sodium nitrate and 0.2 g of 0.1 wt% riboflavin solution were added to a reactor, and the pH value was adjusted to 6 with deionized water to obtain a composite bacterial culture medium; 1.8 mL of Bacillus licheniformis suspension, 1.8 mL of Bacillus subtilis suspension, 2.4 mL of Rhodopseudomonas palustris suspension, 3.0 mL of Rhodobacter sphaeroides suspension and 1.0 mL of enzyme-producing lytic Bacillus suspension were inoculated into 200 g of the composite bacterial culture medium and cultured at 30°C for 100 h to obtain a composite bacterial liquid.

[0034] By combining shrimp shell hydrolyzate to supply chitin-derived nutrients, fish meal peptone to provide a slow-release nitrogen source, sodium nitrate to optimize electron transfer, and riboflavin to enhance photosynthetic efficiency, combined with the synergistic combination of five bacteria, efficient pollutant removal can be achieved to solve the problem of synergistic pollution of ammonia nitrogen, nitrite, hydrogen sulfide and algae in aquaculture.

[0035] The hollow glass microspheres have a density of 0.1–0.6 g / cm³ and a particle size of 10–200 μm; the gelatin tape is 0.3 mm thick; and the elliptical capsules are 5×7 mm in size.

[0036] The method of using water quality improver for aquaculture includes the following steps: For open ponds, use 200g / mu·m water quality improver, and for circulating water systems, add 50g / m 3 , cage culture according to 100g / bag (net bag: 40×60cm) per 10m 3 Hang 1 bag; before use, press 1g of improver: 10mL of water, stir for 10-20 minutes, and activate it. After activation, evenly sprinkle it against the wind in the open-air pond, inject it into the circulating water system in proportion, and hang the cage at a water depth of 1.5-3m. Oxygenation must be synchronized throughout the addition process to promote the release of active substances through water flow.

[0037] Example 2: A water quality improver for aquaculture, comprising the following components in parts by mass: 45 parts of composite biochar, 9 parts of bentonite, 55 parts of deionized water, 9 parts of hollow glass microspheres, 18 parts of cod liver oil and 37.5 parts of antibacterial composite hydrogel.

[0038] The preparation method of the water quality improver for aquaculture comprises the following steps: Step 1: Add composite biochar, bentonite and deionized water into a ball mill and mill for 25 minutes, then add hollow glass microbeads and mill for 15 minutes to obtain the main material; add cod liver oil and antibacterial composite hydrogel into an emulsifier and homogenize and emulsify for 12.5 minutes to obtain the auxiliary material; Step 2: Close the glue outlet on both sides of the fully automatic pill press, preheat the glue outlet to 35°C, connect the rubber hose and the air pipe, transport the main material into the gelatin box, open the glue outlet to form a continuous gelatin tape, add the auxiliary material when the tape passes through the rotating mold, press the mold to form an elliptical capsule, dry it at 35°C for 2.5h, spray 10wt% citric acid ethanol solution for 12.5s, and vacuum dry to obtain a water quality improver for aquaculture.

[0039] Specifically, the composite biochar is prepared by the following steps: The walnut shell derivative was refluxed in 6wt% hydrochloric acid for 1.5h, washed with ultrapure water until neutral, filtered, dried, and calcined at 450℃ under nitrogen protection for 2.5h to obtain pretreated biochar; 12g titanium dioxide / iron-manganese nanosheets, 2g pretreated biochar and 270mL deionized water were added to the reactor, stirred at 350rpm for 2.5h, transferred to a 500mL stainless steel reactor lined with polytetrafluoroethylene, reacted at 170℃ for 7h, cooled to room temperature, filtered, vacuum dried at 75℃ to constant weight, ground, and passed through a 100-mesh sieve to obtain composite biochar.

[0040] Specifically, titanium dioxide / iron-manganese nanosheets are prepared by the following steps: 5 g of ferric chloride hexahydrate, 5 g of manganese sulfate and 95 mL of deionized water were added to a reactor and stirred at 65 ° C for 12.5 minutes to obtain a mixed metal solution; 10.0 g of anatase nano-titanium dioxide and 0.95 L of deionized water were added to the reactor, ultrasonicated for 25 minutes, and then 50 mL of the mixed metal solution, 95 mL of 1 wt% sodium citrate solution and 500 mL of 1 wt% ascorbic acid solution were added, nitrogen was introduced for 25 minutes, and the mixture was stirred at 325 rpm in a light-shielded state for 25 minutes. The bottom of a 365 nm ultraviolet lamp was placed 7.5 cm above the liquid surface, the light was turned on, and the mixture was reacted in a 45 ° C water bath for 3.5 hours. The suspension turned brown-black, was filtered, and washed repeatedly with 1 wt% sodium citrate solution and nitrogen-saturated ethanol until the water was clear, and vacuum dried to constant weight to obtain titanium dioxide / iron-manganese nanosheets.

[0041] Specifically, the antibacterial composite hydrogel is prepared by the following steps: 25 mL of composite bacterial liquid was added to the reactor, centrifuged for 12.5 minutes, the bacteria were collected, transferred to 7.5 mL of phosphate buffer and 12.5 mL of 4 wt% sodium alginate solution and stirred for 25 minutes, and then 0.9 mL of 0.1 wt% calcium chloride solution was added dropwise and solidified for 25 minutes to obtain core-shell antibacterial microspheres; 3.25 g of gelatin and 35 mL of deionized water were added to the reactor, stirred at 55 ° C for 25 minutes, 0.75 g of tannic acid was added, the pH value was adjusted to 8 with sodium hydroxide, stirred for 12.5 minutes, and then 0.75 g of core-shell antibacterial microspheres was added, stirred for 7.5 minutes, poured into a mold and frozen at -25 ° C for 1.5 hours, and thawed at room temperature to obtain an antibacterial composite hydrogel.

[0042] Specifically, the composite bacterial solution is prepared by the following steps: 4 g of 1.5 wt% shrimp shell hydrolyzate, 0.7 g of 0.3 wt% fish meal peptone, 0.09 g of 0.04 wt% sodium nitrate and 0.3 g of 0.1 wt% riboflavin solution were added to a reactor, and the pH value was adjusted to 6 with deionized water to obtain a composite bacterial culture medium; 2.0 mL of Bacillus licheniformis suspension, 2.0 mL of Bacillus subtilis suspension, 2.7 mL of Rhodopseudomonas palustris suspension, 3.3 mL of Rhodobacter sphaeroides suspension and 1.25 mL of enzyme-producing lytic Bacillus suspension were inoculated into 250 g of the composite bacterial culture medium and cultured at 35°C for 110 h to obtain a composite bacterial liquid.

[0043] Example 3: A water quality improver for aquaculture, comprising the following components in parts by mass: 50 parts of composite biochar, 10 parts of bentonite, 60 parts of deionized water, 10 parts of hollow glass microspheres, 20 parts of cod liver oil and 40 parts of antibacterial composite hydrogel.

[0044] The preparation method of the water quality improver for aquaculture comprises the following steps: Step 1: Add composite biochar, bentonite and deionized water into a ball mill and mill for 30 minutes, then add hollow glass microbeads and mill for 20 minutes to obtain the main material; add cod liver oil and antibacterial composite hydrogel into an emulsifier and homogenize and emulsify for 15 minutes to obtain the auxiliary material; Step 2: Close the glue outlet on both sides of the fully automatic pill press, preheat the glue outlet to 40°C, connect the rubber hose and the air pipe, transport the main material into the gelatin box, open the glue outlet to form a continuous gelatin tape, add the auxiliary material when the tape passes through the rotating mold, press the mold to form an elliptical capsule, dry it at 40°C for 3h, spray 10wt% citric acid ethanol solution for 15s, and vacuum dry to obtain a water quality improver for aquaculture.

[0045] Specifically, the composite biochar is prepared by the following steps: The walnut shell derivative was refluxed in 6wt% hydrochloric acid for 2h, washed with ultrapure water until neutral, filtered, dried, and calcined at 500℃ under nitrogen protection for 3h to obtain pretreated biochar; 15g titanium dioxide / iron-manganese nanosheets, 3g pretreated biochar and 300mL deionized water were added to the reactor, stirred at 400rpm for 3h, transferred to a 500mL stainless steel reactor lined with polytetrafluoroethylene, reacted at 180℃ for 8h, cooled to room temperature, filtered, vacuum dried at 80℃ to constant weight, ground, and passed through a 100-mesh sieve to obtain composite biochar.

[0046] Specifically, titanium dioxide / iron-manganese nanosheets are prepared by the following steps: 5.5 g of ferric chloride hexahydrate, 5.5 g of manganese sulfate and 100 mL of deionized water were added to a reactor and stirred at 70 ° C for 15 minutes to obtain a mixed metal solution; 11.0 g of anatase nano-titanium dioxide and 1.0 L of deionized water were added to the reactor, ultrasonicated for 30 minutes, and then 55 mL of the mixed metal solution, 100 mL of 1 wt% sodium citrate solution and 550 mL of 1 wt% ascorbic acid solution were added, nitrogen was introduced for 30 minutes, and the mixture was stirred at 350 rpm in a light-shielded state for 30 minutes. The bottom of a 365 nm ultraviolet lamp was placed 10 cm above the liquid surface, the light was turned on, and the mixture was reacted in a 50 ° C water bath for 4 hours. The suspension turned brown-black, was filtered, and washed repeatedly with 1 wt% sodium citrate solution and nitrogen-saturated ethanol until the water was clear, and vacuum dried to constant weight to obtain titanium dioxide / iron-manganese nanosheets.

[0047] Specifically, the antibacterial composite hydrogel is prepared by the following steps: 30 mL of composite bacterial liquid was added to the reactor, centrifuged for 15 minutes, the bacteria were collected, transferred to 10 mL of phosphate buffer and 15 mL of 4 wt% sodium alginate solution, stirred for 30 minutes, and then 1.0 mL of 0.1 wt% calcium chloride solution was added dropwise and solidified for 30 minutes to obtain core-shell antibacterial microspheres; 3.5 g of gelatin and 40 mL of deionized water were added to the reactor, stirred at 60 ° C for 30 minutes, 1.0 g of tannic acid was added, the pH value was adjusted to 8 with sodium hydroxide, stirred for 15 minutes, and then 1.0 g of core-shell antibacterial microspheres was added, stirred for 10 minutes, poured into a mold and frozen at -20 ° C for 2 hours, and thawed at room temperature to obtain an antibacterial composite hydrogel.

[0048] Specifically, the composite bacterial solution is prepared by the following steps: 5 g of 1.5 wt% shrimp shell hydrolyzate, 0.8 g of 0.3 wt% fish meal peptone, 0.10 g of 0.04 wt% sodium nitrate and 0.4 g of 0.1 wt% riboflavin solution were added to a reactor, and the pH value was adjusted to 6 with deionized water to obtain a composite bacterial culture medium; 2.2 mL of Bacillus licheniformis suspension, 2.2 mL of Bacillus subtilis suspension, 3.0 mL of Rhodopseudomonas palustris suspension, 3.6 mL of Rhodobacter sphaeroides suspension and 1.5 mL of enzyme-producing lytic Bacillus suspension were inoculated into 300 g of the composite bacterial culture medium and cultured at 40°C for 120 h to obtain a composite bacterial liquid.

[0049] The material raw materials used in Examples 1 to 3 of the present application are all commercially available, such as hollow glass microspheres selected from Hebei Huishun Mining Co., Ltd. (Huishun Mining); walnut shell derivatives selected from Lingshou County Yaoyang Mineral Products Processing Plant (Yaoyang); anatase nano-titanium dioxide selected from Nanjing Tianxing New Materials Co., Ltd. (TTP-A12); Bacillus licheniformis suspension selected from Pusrui (Shanghai) Biomedicine Co., Ltd. (SHMCC); Bacillus subtilis suspension selected from Hangzhou Muyun Technology Co., Ltd. (ACEtest); Rhodopseudomonas palustris suspension selected from Shanghai Lianmai Bioengineering Co., Ltd. (ATCC336448); spherical red bacteria suspension selected from Beijing Biobowei Biotechnology Co., Ltd. (bio-56574); enzyme-producing lysozyme suspension selected from Shanghai Xuanke Biotechnology Co., Ltd. (XK-JZ-1020).

[0050] Comparative Example 1: The difference from Example 3 is that in the step of preparing titanium dioxide / iron-manganese nanosheets, anatase nano-titanium dioxide and ultraviolet light irradiation are not added, and the other steps remain unchanged to prepare a water quality improver.

[0051] Comparative Example 2: The difference from Example 3 is that in the step of preparing the composite biochar, the walnut shell derivative is replaced by a corn straw derivative, and the other steps remain unchanged to prepare the water quality improver.

[0052] Comparative Example 3: The difference from Example 3 is that in the step of preparing the antibacterial composite hydrogel, the sodium alginate and calcium chloride coating is not performed, and the other steps remain unchanged to prepare the water quality improver.

[0053] The water quality improvers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were sprayed at a rate of 200 g / mu·m on an open-air pond with poor water color and deteriorated water quality. After 7 days, the adsorption rate, impurity removal rate, chemical oxygen demand, and chemical oxygen demand degradation rate were tested. The results are shown in Table 1: Table 1: Performance test results of water quality improvers for aquaculture project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Adsorption rate% 95.5 96.2 97.5 67.1 63.8 78.6 Impurity removal rate% 92.2 92.7 93.3 78.9 74.4 68.7 Chemical oxygen demand mg / L 13.3 12.4 11.8 48.1 37.6 30.2 Chemical oxygen demand degradation rate% 95.3 95.7 96.6 70.1 81.1 75.6 As can be seen from Table 1, the purification effect of the water quality improvers prepared in Examples 1 to 3 is significantly better than that in Comparative Examples 1 to 3; they utilize the high specific surface area of ​​walnut shell biochar and bentonite to efficiently adsorb pollutants, titanium dioxide / iron-manganese nanosheets to rapidly degrade ammonia nitrogen under ultraviolet light and adsorb heavy metals, and calcium alginate-encapsulated probiotics to achieve sustained release and antibacterial properties, stabilize the microecology, and synergistically achieve the trinity of "adsorption-photocatalytic degradation-biological antibacterial", significantly improving the organic matter removal rate and water quality stability.

[0054] In Comparative Example 1, the chemical oxygen demand degradation rate decreased significantly and the chemical oxygen demand increased significantly. This may be due to the lack of anatase nano-titanium dioxide and ultraviolet light irradiation, which greatly reduced the photocatalytic effect of titanium dioxide / iron-manganese nanosheets in producing strong oxidizing active substances under ultraviolet excitation. As a result, the adsorbed biochar can only enrich pollutants but cannot be completely decomposed, directly weakening the chemical degradation ability of organic matter and causing continuous accumulation of organic matter.

[0055] In Comparative Example 2, the adsorption rate decreased significantly, which may be due to the deterioration of structural performance caused by replacing walnut shell derivatives with corn straw derivatives. The dense wood structure of walnut shells can form hierarchical pores, and its micropores and mesoporous structures can synergistically adsorb pollutants of different molecular weights. In addition, the walnut shell carbon surface roughness is high, and the titanium dioxide / iron-manganese nanosheets are firmly bonded; the corn straw ash content is high, and the ash melts and blocks the pores during high-temperature calcination, and the hemicellulose content is high, and pyrolysis produces more alkaline ash, which reduces the specific adsorption of heavy metals / organic acids.

[0056] In Comparative Example 3, the impurity removal rate decreased significantly. This may be because the uncoated bacterial community was inactivated due to exposure to the salinity, pH fluctuations, and competition from native microorganisms in the water environment without sodium alginate and calcium chloride coating. At the same time, due to the loss of density control, it was impossible to target the pollution-enriched area, and the core ability of antibacterial decomposition and inhibition of pathogenic microorganisms was lost, resulting in a decrease in the efficiency of biological impurity removal.

[0057] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A water quality improver for aquaculture, characterized in that: Calculated by mass, it includes the following components and raw materials: 40-50 parts of composite biochar, 8-10 parts of bentonite, 50-60 parts of deionized water, 8-10 parts of hollow glass microspheres, 16-20 parts of cod liver oil and 35-40 parts of antibacterial composite hydrogel; The composite biochar is prepared by combining walnut shell derivatives and titanium dioxide / iron-manganese nanosheets; The titanium dioxide / iron-manganese nanosheets are prepared by the following steps: Ferric chloride hexahydrate, manganese sulfate and deionized water are stirred to obtain a mixed metal solution; anatase nano-titanium dioxide, deionized water, the mixed metal solution, 1wt% sodium citrate solution and 1wt% ascorbic acid solution are stirred under nitrogen in the dark, and ultraviolet light is used for catalytic reduction deposition to obtain titanium dioxide / iron-manganese nanosheets.

2. The water quality improver for aquaculture according to claim 1, characterized in that: The composite biochar is specifically prepared by the following steps: The walnut shell derivative is acid-washed and refluxed for 1-2 hours, washed with ultrapure water until neutral, filtered, dried, and calcined at 400-500°C under nitrogen protection for 2-3 hours to obtain pretreated biochar; titanium dioxide / iron-manganese nanosheets, pretreated biochar and deionized water are added to a reactor, stirred at 300-400 rpm for 2-3 hours, transferred to a 500 mL polytetrafluoroethylene-lined stainless steel reactor, reacted at 160-180°C for 6-8 hours, cooled to room temperature, filtered, vacuum dried at 70-80°C to constant weight, ground, and passed through a 100-mesh sieve to obtain composite biochar.

3. A water quality improver for aquaculture according to claim 2, characterized in that The dosage ratio of the titanium dioxide / iron-manganese nanosheets, pretreated biochar and deionized water is 9-15 g: 1-3 g: 240-300 mL.

4. The water quality improver for aquaculture according to claim 3, characterized in that The titanium dioxide / iron-manganese nanosheets are specifically prepared by the following steps: Ferric chloride hexahydrate, manganese sulfate and deionized water are added to a reactor and stirred at 60-70°C for 10-15 minutes to obtain a mixed metal solution; anatase nano-titanium dioxide and deionized water are added to the reactor, ultrasonicated for 20-30 minutes, and then the mixed metal solution, 1wt% sodium citrate solution and 1wt% ascorbic acid solution are added, nitrogen is introduced for 20-30 minutes, and the mixture is stirred at 300-350rpm in a light-shielded manner for 20-30 minutes. The bottom of a 365nm ultraviolet lamp is placed 5-10 cm above the liquid surface, the light is turned on, and the mixture is reacted in a water bath at 40-50°C for 3-4 hours. The suspension turns brown-black, is filtered, and repeatedly washed with 1wt% sodium citrate solution and nitrogen-saturated ethanol until the water is clear, and then vacuum dried to constant weight to obtain titanium dioxide / iron-manganese nanosheets.

5. The water quality improver for aquaculture according to claim 4, characterized in that: The usage ratio of the ferric chloride hexahydrate, manganese sulfate and deionized water is 4.5-5.5 g: 4.5-5.5 g: 90-100 mL; the usage ratio of the anatase nano-titanium dioxide, deionized water, mixed metal solution, sodium citrate solution and ascorbic acid solution is 9.0-11.0 g: 0.9-1.0 L: 45-55 mL: 90-100 mL: 450-550 mL.

6. The water quality improver for aquaculture according to claim 1, characterized in that: The antibacterial composite hydrogel is specifically prepared by the following steps: The composite bacterial liquid is added to the reactor, centrifuged for 10-15 minutes, the bacteria are collected, transferred to phosphate buffer and 4wt% sodium alginate solution, stirred for 20-30 minutes, and then 0.1wt% calcium chloride solution is added dropwise and solidified for 20-30 minutes to obtain core-shell antibacterial microspheres; gelatin and deionized water are added to the reactor, stirred at 50-60°C for 20-30 minutes, tannic acid is added, the pH value is adjusted to 8 with sodium hydroxide, stirred for 10-15 minutes, and then the core-shell antibacterial microspheres are added, stirred for 5-10 minutes, poured into a mold, frozen at -30°C to -20°C for 1-2 hours, and thawed at room temperature to obtain an antibacterial composite hydrogel.

7. The water quality improver for aquaculture according to claim 6, characterized in that: The dosage ratio of the composite bacterial solution, phosphate buffer, sodium alginate solution and calcium chloride solution is 20-30 mL: 5-10 mL: 10-15 mL: 0.8-1.0 mL; the dosage ratio of the gelatin, deionized water, tannic acid and core-shell antibacterial microspheres is 3.0-3.5 g: 30-40 mL: 0.5-1.0 g: 0.5-1.0 g.

8. The water quality improver for aquaculture according to claim 7, characterized in that: The composite bacterial solution is specifically prepared by the following steps: 1.5wt% shrimp shell hydrolyzate, 0.3wt% fish meal peptone, 0.04wt% sodium nitrate and 0.1wt% riboflavin solution are added to a reactor, and the pH value is adjusted to 6 with deionized water to obtain a composite bacterial culture medium; a Bacillus licheniformis suspension, a Bacillus subtilis suspension, a Rhodopseudomonas palustris suspension, a Rhodobacter sphaeroides suspension and an enzyme-producing Bacillus lysogenus suspension are inoculated into the composite bacterial culture medium, and the mixture is cultured at 30-40°C for 100-120 hours to obtain a composite bacterial liquid.

9. The water quality improver for aquaculture according to claim 8, characterized in that: The mass ratio of the shrimp shell hydrolyzate, fish meal peptone, sodium nitrate and riboflavin is 3-5:0.6-0.8:0.08-0.1:0.2-0.4; the dosage ratio of the Bacillus licheniformis suspension, Bacillus subtilis suspension, Rhodopseudomonas palustris suspension, Rhodobacter sphaeroides suspension, Bacillus enzyme-producing lysogeny suspension and composite bacterial culture medium is 1.8-2.2 mL:1.8-2.2 mL:2.4-3.0 mL:3.0-3.6 mL:1.0-1.5 mL:200-300 g.

10. The method for preparing a water quality improver for aquaculture according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: Step 1: Add composite biochar, bentonite and deionized water into a ball mill, and ball mill for 20-30 minutes, then add hollow glass microbeads and ball mill for 10-20 minutes to obtain the main material; add cod liver oil and antibacterial composite hydrogel into an emulsifier, homogenize and emulsify for 10-15 minutes to obtain the auxiliary material; Step 2: Close the glue outlets on both sides of the fully automatic pill press, preheat the glue outlets to 30-40°C, connect the rubber hose and the air pipe, transport the main material into the gelatin box, open the glue outlet to form a continuous gelatin tape, add the auxiliary material when the tape passes through the rotating mold, press the mold to form an elliptical capsule, dry it at 30-40°C for 2-3h, spray 10wt% citric acid ethanol solution for 10-15s, and vacuum dry to obtain a water quality improver for aquaculture.