A biological nitrite removal product, its preparation method and application

Abstract

This invention belongs to the field of environmental microbiology technology and water treatment, specifically disclosing a biological nitrite removal product, its preparation method, and its application. The biological nitrite removal product consists of Bacillus tropicalis powder, a silica-based carrier, and sodium bicarbonate. The silica-based carrier provides attachment sites for microorganisms, greatly increasing the contact area between the microorganisms and nitrite, thus promoting the reaction. Bacillus tropicalis is the core microorganism for efficiently degrading nitrite; during its growth and metabolism, it secretes specific enzymes that gradually assimilate nitrite into harmless substances such as bacterial nitrogen. Sodium bicarbonate plays a crucial role in regulating the pH of the system, creating a suitable living and metabolic environment for Bacillus tropicalis, ensuring its activity and degradation efficiency. This biological nitrite removal product features effective nitrite degradation, high efficiency, low nitrite content rebound, relatively stable ammonia nitrogen content, and safety without pollution, making it particularly suitable for aquaculture.

Description

Technical Field

[0001] This invention relates to the fields of environmental microbiology technology and water treatment, specifically to a nitrite removal product based on microbial degradation, its preparation method, and its application. This product is suitable for aquaculture (such as seawater or freshwater aquaculture ponds and recirculating aquaculture systems), and can specifically encompass the integrated application of multiple interdisciplinary fields such as biological water treatment and immobilized microbial technology. Background Technology

[0002] In numerous fields, such as aquaculture and wastewater treatment, the presence of nitrite is a critical issue that urgently needs to be addressed. In aquaculture, with the continuous expansion of farming scale and increasing intensification, overstocking and concentrated feeding have led to the accumulation of large amounts of uneaten feed, feces, and dead animal and plant carcasses in the water. These organic materials decompose and ferment under the action of heterotrophic bacteria at the bottom of the pond, gradually breaking down proteins and nucleic acids and releasing large amounts of nitrogenous harmful substances, causing a sharp increase in the concentration of ammonia nitrogen and nitrite in the water. High concentrations of nitrite reduce the oxygen-carrying capacity of the blood of farmed animals, causing hemoglobin to convert to methemoglobin, which loses its oxygen-carrying function, directly harming the health of farmed animals. Furthermore, long-term accumulation and poisoning can reduce the disease resistance of fish and shrimp, making them susceptible to pathogens and causing large-scale disease outbreaks, resulting in huge economic losses for farmers and becoming a serious obstacle to the development of the aquaculture industry. In wastewater treatment, especially the treatment of slightly polluted water, nitrite removal is also a major challenge.

[0003] Currently, methods for removing nitrite mainly include physical adsorption, chemical methods, and biological methods. While physical adsorption can reduce nitrite concentration to some extent, it suffers from limited adsorption capacity, easy saturation, and potential secondary pollution. Chemical methods typically use strong oxidants to oxidize nitrite to nitrate; however, this process may introduce harmful chemical residues, affecting the ecological balance of aquatic bodies, and is difficult to achieve complete nitrite degradation. Biological methods, as an economical, feasible, and efficient treatment approach, have received considerable attention in recent years. This method mainly utilizes the life activities of various microorganisms to degrade nitrite into harmless substances, offering significant advantages such as low cost, no secondary pollution, and no harm to organisms. However, traditional biological methods rely on single microbial strains, are greatly affected by environmental factors, and have unstable degradation efficiency, failing to meet the demand for efficient nitrite removal in complex environments.

[0004] Based on existing literature and practical application surveys, there are currently no publicly reported cases of successfully applying physical, chemical, and microbial treatment technologies to the preparation and application of nitrite removal products. Therefore, developing a biological-based method for the preparation and application of nitrite removal products is not only academically innovative but also has significant practical application value. Summary of the Invention

[0005] Therefore, the present invention aims to provide an innovative biological nitrite removal product that overcomes the shortcomings of existing technologies through a unique formulation and synergistic mechanism.

[0006] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a tropical Bacillus strain with highly efficient nitrite degradation capabilities. The strain is named Bacillus tropicus SHOU-1 and is deposited at the China Center for Type Culture Collection (CCTCC), located at No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province, on May 13, 2026, with accession number CCTCC NO: M 2026947.

[0008] Secondly, the present invention provides a biological nitrite removal product comprising the following components: Bacillus tropicus SHOU-1 bacterial powder, a silicon-based carrier, and sodium bicarbonate.

[0009] In this invention's biological nitrite removal product, Bacillus tropicalis possesses a highly efficient nitrite degradation capacity, converting nitrite into harmless substances through its own metabolic activities. The silicon-based carrier has a porous structure, which on the one hand provides a large number of attachment sites for Bacillus tropicalis, promoting the aggregation and growth of microorganisms; on the other hand, it can rapidly reduce the initial concentration of nitrite in water through physical adsorption, while adsorbing other harmful substances in the water and improving water quality. Sodium bicarbonate is used to adjust the pH of the water, creating a suitable living and metabolic environment for Bacillus tropicalis, maintaining the chemical balance of the water, and enhancing the stability and durability of the product's effects.

[0010] Preferably, the silicon-based carrier is a calcined silicon dioxide product, which has high porosity, large specific surface area and stable chemical properties.

[0011] Further, the calcined silica product is prepared by the following method: Sodium-calcium glass (such as flat glass, bottle glass) is cleaned and ground into glass powder by a ball mill; the glass powder is thoroughly mixed with carbon powder and additives (such as feldspar, borax); the mixture is placed in a granulator, a binder is added, and it is pressed into shape; the shaped material is fed into a tunnel kiln or a continuous high-temperature furnace and heated to 800-950°C for sintering and foaming; finally, the temperature is slowly reduced for annealing to obtain the calcined silica product.

[0012] Preferably, the components of the biological nitrite removal product, by mass percentage, are: 20-30% silicon-based carrier, 20-25% Bacillus tropicalis powder, and 50-60% sodium bicarbonate, with a total of 100%. The specific proportions can be flexibly adjusted based on factors such as the initial concentration of nitrite and water quality characteristics in the target application scenario. In one specific embodiment, the silicon-based carrier accounts for 30%, the Bacillus tropicalis powder accounts for 20%, and the sodium bicarbonate accounts for 50%.

[0013] Thirdly, the present invention provides a method for preparing the above-mentioned biological nitrite removal product, comprising the following steps:

[0014] (1) Pretreatment of silicon-based carrier: The silicon-based carrier is cleaned to remove surface impurities; then it is dried at a specific temperature to ensure that the internal pores of the silicon-based carrier are unobstructed, creating good conditions for microbial attachment; then it is crushed and ground.

[0015] (2) Culture and powder preparation of Bacillus tropicalus: Bacillus tropicalus SHOU-1 with high nitrite degradation activity was cultured in a liquid culture medium rich in nitrogen source, carbon source and various trace elements; when the bacterial growth entered the stable period, the bacterial cells were collected by centrifugation, filtration and other methods, and then freeze-dried or spray-dried to produce Bacillus tropicalus powder;

[0016] (3) Product mixing and preparation: Mix the pretreated silicon-based carrier, Bacillus tropicalis powder and sodium bicarbonate thoroughly according to the mass ratio.

[0017] Preferably, in step (1), the silicon-based carrier needs to be crushed and ground to 100 mesh.

[0018] Preferably, in step (2), the temperature during the expansion culture process is strictly controlled at 35-40℃, which is the optimal temperature range for the growth of tropical Bacillus. At the same time, sterile air is continuously introduced to meet its aerobic respiration requirements. The expansion culture time is controlled at 8-12h.

[0019] Preferably, in step (2), the culture medium formula for the expanded culture is: 5g glucose, 10g soybean meal powder, 2g yeast extract, 1g potassium dihydrogen phosphate, 0.5g magnesium sulfate, and 1000mL distilled water.

[0020] Preferably, in step (2), the bacterial cells are dried by spray drying. Specifically, the bacterial cells are first mixed with a protective agent to form a bacterial suspension, and then sent to a spray drying device for drying. The protective agent includes, by mass percentage: 5-10% skim milk powder, 2-5% trehalose, and the remainder is water.

[0021] Preferably, in step (2), after the bacterial cells are dried, they are mixed evenly with a carrier (such as calcium carbonate or starch, with a mass ratio of 30%-50%) to retain the bacterial cell activity to the greatest extent, thereby obtaining the finished product of Bacillus tropicalis powder.

[0022] Preferably, in step (3), the mixing process is carried out by mechanical stirring or airflow mixing to ensure that the components are evenly distributed and to obtain the final biological nitrite removal product.

[0023] Fourthly, the present invention provides the application of the above-mentioned Bacillus tropicus SHOU-1 in the preparation of biological nitrite removal products.

[0024] Fifthly, the present invention provides the application of the above-mentioned biological nitrite removal product as a nitrite removal agent in aquaculture, sewage treatment and other fields.

[0025] This invention combines modern bacterial powder preparation technology with traditional adsorption silicon-based carrier preparation theory. It uses Bacillus tropicus SHOU-1 to prepare Bacillus tropicus bacterial powder, employs sodium bicarbonate as a buffer, and utilizes a silicon-based carrier as the adsorption silicon-based carrier. The aim is to achieve the goal of microbial removal of nitrite from water, thereby constructing a product with high safety and excellent nitrite removal function. This is of great significance for improving the ability of aquaculture water to remove nitrite and is also applicable to the preparation and promotion of other products for regulating aquaculture water environments, possessing significant practical application value and industrialization prospects.

[0026] Compared to traditional physical, chemical, or microbial treatment methods, this invention achieves a systematic improvement in effectiveness, safety, removal efficiency, and environmental friendliness. The core technical effects of this invention are detailed below:

[0027] I. Highly efficient and rapid degradation of nitrite, directly addressing the core pollution problem.

[0028] The product achieves efficient removal of nitrite through a triple mechanism of "biodegradation + physical adsorption + buffering regulation".

[0029] 1. Tropical Bacillus, as a core functional strain, can reduce nitrite (NO) through nitrate assimilation. 2- It is converted into bacterial nitrogen, directly cutting off the accumulation pathway of nitrite;

[0030] 2. Due to its porous structure (specific surface area can reach 50-100m² / g), the silicon-based carrier plays a physical adsorption auxiliary role, which can quickly adsorb free nitrite in water, reduce the initial concentration, and enrich it around the bacteria, providing a high concentration of substrate for Bacillus tropicalis and accelerating the biodegradation efficiency.

[0031] 3. With synergistic effect, the product can reduce the concentration of excessive nitrite (such as >0.5mg / L in aquaculture) to the safe threshold (<0.15mg / L) within 24-72 hours. The degradation rate is 30%-50% higher than that of a single bacterial agent, solving the problem of short-term explosive exceedance of nitrite.

[0032] II. Long-lasting and stable effect, avoiding secondary rebound.

[0033] By relying on silicon-based carrier fixation and environmental optimization design, the product's performance stability has been significantly improved.

[0034] The silicon-based carrier, acting as a bacterial immobilization carrier, can "anchor" Bacillus tropicalis through its porous structure, reducing strain loss due to water flow and extending the survival period of the strain in the water, thus ensuring continuous degradation capacity. Sodium bicarbonate provides a suitable metabolic environment for Bacillus tropicalis by adjusting the alkalinity and buffering the pH (stabilizing it at 6.5-8.5), preventing a decrease in strain activity due to environmental fluctuations. Compared with traditional chemical degradation agents (such as nitrite reductase preparations), the product can effectively inhibit nitrite rebound, continuously controlling the nitrite concentration within a safe range throughout the breeding cycle, reducing the rebound rate by more than 60%.

[0035] III. Improve the microecology and physicochemical environment of aquatic bodies and enhance overall water quality.

[0036] While degrading nitrite, the product simultaneously optimizes the ecological and physicochemical indicators of the water body.

[0037] Microecological balance restoration: During the metabolism of tropical Bacillus, extracellular enzymes and growth factors can be secreted, which can promote the proliferation of beneficial microorganisms such as photosynthetic bacteria and lactic acid bacteria in water, inhibit the growth of pathogenic bacteria such as Vibrio, and reduce the risk of aquatic organism diseases;

[0038] The porous structure of the silicon-based carrier provides a micro-habitat for microorganisms, accelerating the reconstruction of the aquatic micro-ecosystem; physicochemical regulation: sodium bicarbonate releases HCO3... - It replenishes carbon sources, promotes algal photosynthesis, and buffers pH fluctuations in water, avoiding acidification problems that may occur during nitrite degradation. The silicon-based carrier can adsorb some ammonia nitrogen and organic matter in the water, ultimately achieving a virtuous cycle of "nitrite degradation - dissolved oxygen enhancement - microecological balance", improving water transparency and self-purification capacity.

[0039] IV. Wide range of applicable scenarios, safe and without secondary pollution

[0040] The product is adaptable to multiple scenarios and has excellent environmental compatibility.

[0041] Scope of application: With its pH buffering and silicon-based carrier fixation design, it can be adapted to freshwater aquaculture (fish ponds, shrimp ponds), marine aquaculture (sea cucumber ponds, shellfish ponds), and small-scale domestic sewage treatment scenarios. It can tolerate water conditions with a salinity range of 0-35‰ and an initial pH of 5.5-9.0. Safety assurance: The Bacillus tropicalis strain is environmentally friendly (non-pathogenic). The silicon-based carrier (mainly composed of SiO2) and sodium bicarbonate are free of heavy metals, antibiotics, and other toxic residues. Acute toxicity tests on aquatic organisms such as fish, shrimp, and algae show a mortality rate of 0%. Aquaculture products meet food safety standards. Ease of operation: The product is in powder or granular form and can be directly dry-spread or dissolved and then sprayed. No complicated equipment is required, and a single person can complete the application. It is suitable for large-scale aquaculture or small-scale application scenarios.

[0042] This product achieves efficient degradation, sustained control, ecological improvement, and safe compatibility of nitrite through a synergistic mechanism of "biodegradation (Bacillus tropicalis) - physical enhancement (silicon-based carrier) - environmental optimization (sodium bicarbonate)". It provides an integrated solution of "pollution reduction + ecological stabilization" for the treatment of nitrite pollution in water bodies. In particular, it can significantly improve the survival rate and product quality of aquaculture, and reduce environmental treatment costs in the field of ecological restoration. Attached Figure Description

[0043] Figure 1 Images of sodium bicarbonate, a silicon-based carrier (calcined silica), and Bacillus tropicalis powder, and their combinations. In the images: A represents the silicon-based carrier; B represents Bacillus tropicalis powder; C represents sodium bicarbonate; and D represents a mixture of sodium bicarbonate, the silicon-based carrier, and Bacillus tropicalis powder. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are merely illustrative of the invention and not intended to limit it. Any modifications made by those skilled in the art after reading this specification, as long as they fall within the scope of the claims, will be protected by patent law.

[0045] Example 1: Test on the ability of Bacillus tropicalis powder to remove nitrite from aquaculture water

[0046] I. Screening of Bacillus tropicus SHOU-1 strain

[0047] Screening for highly efficient nitrite-degrading strains follows these steps:

[0048] 1. Sample collection and pretreatment

[0049] 1.1 Collection: 500g of bottom water sample (near the bottom mud) or silt around a perch farming pond in Huai'an, Jiangsu Province, was placed in a sterile bottle.

[0050] 1.2 Place the collected water or mud suspension in an 80°C water bath for 10-15 minutes.

[0051] 1.3 Enrichment culture: The heat-shocked samples were inoculated into LB medium liquid culture and cultured with shaking at 30-37°C for 12-24 hours.

[0052] 2. Separation and purification (gradient dilution plating)

[0053] Dilution: The enriched solution was serially diluted (10) -3 Up to 10 -6 ).

[0054] Spreading: Spread bacterial solutions of different dilutions onto LB agar plates and invert them in a 30°C incubator for 18-24 hours.

[0055] Colony selection: Select single colonies with typical morphology (smooth edges, milky white or pale yellow, rough or wrinkled surface) and perform streak purification.

[0056] 3. Preliminary identification and screening

[0057] Morphological identification: Perform Gram staining (should be purple, Gram positive) and spore staining (observe whether spores are produced).

[0058] 4. Denitrification function verification: Strains with denitrification function were screened in denitrification medium.

[0059] 5. Molecular biological identification

[0060] Genomic DNA was extracted from the purified strain; PCR amplification was performed using universal primers for bacterial 16S rRNA; the amplified product was sequenced by Sanger sequencing, and the sequenced sequence was compared with the NCBI BLAST database, identifying it as Bacillus tropicus. The strain was named Bacillus tropicus SHOU-1.

[0061] Bacillus tropicus SHOU-1, selected through the above process, has been deposited at the China Center for Type Culture Collection (No. 299, Bayi Road, Wuchang District, Wuhan, Hubei Province) on May 13, 2026, with accession number CCTCCNO: M 2026947.

[0062] II. Preparation of Mycelium Powder

[0063] 1. Strain activation: The lyophilized Bacillus tropicus SHOU-1 strain was activated by shaking (37°C, shake incubation for 12-24 hours). Single colonies were purified by gradient plating and multiple streak plating. The purified Bacillus tropicus SHOU-1 single colonies were streaked onto NB solid agar slant medium and incubated at 35°C for 24 hours to complete the activation. A mature activated slant strain was obtained. Single colonies were picked from the slant and inoculated into Erlenmeyer flasks containing NB liquid medium (1 / 3-1 / 2 of the flask volume). The flasks were incubated at 35-37°C and 150-200 rpm for 12-18 hours until the late logarithmic growth phase (when the bacterial concentration is high and the activity is strong, OD...). 600 The bacterial solution obtained after seed quality testing (approximately 1.0-1.4) shows no contaminants under microscopic examination and a spore formation rate of <10% (the seed stage is mainly vegetative to ensure proliferation capacity) is called seed solution.

[0064] 2. Scale-up culture: The scale-up culture medium formula is: 5g glucose, 10g soybean meal powder, 2g yeast extract, 1g potassium dihydrogen phosphate, 0.5g magnesium sulfate, 1000mL distilled water, pH 7.0-7.2; inoculate the prepared seed culture into the scale-up culture tank at an inoculation rate of 10%, and culture at 35-37℃, stirring speed 200-300r / min, aeration rate of 1:0.5-1:1 (v / v·min) for 8-12 hours, until the cell concentration reaches OD. 600 It reaches 2.0-3.0 and is used as inoculum for fermentation tanks.

[0065] 3. Concentration and separation: Centrifugation (4000-6000 r / min, 10-15 min) was used to collect the bacterial precipitate.

[0066] 4. Spray drying: First, mix the bacterial precipitate with a protectant (5% skim milk powder + 5% trehalose + 90% water) to prepare a bacterial suspension with a solid content of 10%-15%; then send it into the spray drying equipment, controlling the inlet air temperature to 180-200℃ and the outlet air temperature to 70-80℃.

[0067] 5. Preparation of mycelial powder: The dried mycelial cells are pulverized (passed through an 80-100 mesh sieve) to obtain crude mycelial powder. Calcium carbonate is added at a mass ratio of 1:1 and mixed thoroughly to improve flowability and storage stability. Viable cell count: The plate count method (NA medium, incubated at 37℃ for 24 hours) is used, requiring ≥10 viable cells. 9 CFU / g yielded the finished product of Bacillus tropicalis powder.

[0068] III. Test on the effect of bacterial powder on degrading nitrite content

[0069] 50L of lake water was added to an aquarium, along with 0.03g of nitrite and 0.015g of ammonium chloride. The initial nitrite content was determined based on spectrophotometric counting values, and the following amounts of Bacillus tropicalis powder were determined: 50g / mu, 100g / mu, 150g / mu, 200g / mu, 250g / mu, 300g / mu, 350g / mu, 400g / mu, 450g / mu, 500g / mu, and 1000g / mu.

[0070] 1. Experimental group: 11 groups were set up, and the corresponding mass of Bacillus tropicalis powder was added and cultured in an incubator at 37℃ for 3 days.

[0071] 2. Control group: No substance was applied.

[0072] 3. Every 24 hours, 40 mL of water was taken from each experimental group and centrifuged at 5000 r / min for 5 min.

[0073] 4. Use a water quality analyzer (XZ-0125) to determine the nitrite content of each water sample. Repeat the measurement three times and record the average value.

[0074] The results of the nitrite content determination are shown in Table 1 below. The results show that the nitrite removal rate of the 500g / mu Bacillus tropicalis powder experimental group reached 70% within 72 hours, and the nitrite content could be reduced from 0.76mg / L to 0.23mg / L. The 1000g / mu Bacillus tropicalis powder experimental group showed the largest decrease in nitrite content within 72 hours, with a nitrite removal rate of 88% and the nitrite content could be reduced from 0.76mg / L to 0.09mg / L.

[0075] The formula for calculating the nitrite removal rate is as follows:

[0076]

[0077] Table 1. Ability of Bacillus tropicalis powder to remove nitrite from aquaculture water

[0078]

[0079] Example 2: Test on the ability of silicon-based carrier to remove nitrite from prepared aquaculture water

[0080] I. Preparation of Adsorbent Silicon-Based Carrier Powder

[0081] 1. Appearance: Calcinated silica products with uniform color, no obvious impurities, and well-developed pore structure are selected as the silicon-based carrier. The main component is silicon dioxide (SiO2), containing small amounts of aluminum oxide (Al2O3), calcium oxide (CaO), etc., ensuring chemical stability (insoluble in water, no harmful precipitates), hardness, and ease of crushing and grinding. Specifically, the preparation method of the calcined silica products is as follows:

[0082] Sodium-calcium glass is cleaned and ground into glass powder using a ball mill. The glass powder, carbon powder, and borax are then thoroughly mixed in a mass ratio of 95%, 2%, and 3%, respectively. The mixture is then placed in a granulator with a small amount of binder (sodium silicate) added and pressed into shape. The shaped material is then fed into a tunnel kiln or continuous high-temperature furnace and heated to 800°C for sintering and foaming. After 45 minutes, the temperature is slowly reduced for annealing to obtain calcined silica products.

[0083] 2. Drying pretreatment: After cleaning the screened silicon-based carrier, dry it at a constant temperature of 105 ℃ for 2~4 h, and cool it to room temperature to remove the adsorbed moisture from the raw material and prevent grinding agglomeration.

[0084] 3. Crush the particles to a size of 5-10mm (particles that are too small are prone to clumping, while particles that are too large will result in low grinding efficiency) to ensure uniform particle size and reduce subsequent grinding time.

[0085] 4. Grinding the crushed particles into powder of the required fineness is the core step in preparation. Grind to a normal fineness (100 mesh).

[0086] II. Test on the effect of adsorption of silicon-based carrier powder on degradation of nitrite content

[0087] 50L of lake water was added to an aquarium, along with 0.03g of nitrite and 0.015g of ammonium chloride. The initial nitrite content was determined based on spectrophotometric counts, and the final addition amounts of the silicon-based carrier were determined to be: 50g / mu, 100g / mu, 150g / mu, 200g / mu, 250g / mu, 300g / mu, 350g / mu, 400g / mu, 450g / mu, and 500g / mu.

[0088] 1. Experimental group: 10 groups were set up, and the appropriate mass of silicon-based carrier powder was added. The groups were incubated in an incubator at 37℃ for 3 days.

[0089] 2. Control group: No substance was applied.

[0090] 3. Every 24 hours, 40 mL of water was taken from each experimental group and centrifuged at 5000 r / min for 5 min.

[0091] 4. Use a multi-parameter water quality analyzer to determine the nitrite content of each water sample. Repeat the measurement three times and record the average value.

[0092] The results of the nitrite content determination are shown in Table 2 below. The results show that 500g silicon-based carrier / acre is the highest value of each experimental group, and the nitrite value can be reduced from 0.76mg / L to 0.09mg / L. The nitrite degradation rate of the 500g silicon-based carrier / acre experimental group reached 89% within 72 hours.

[0093] Table 2. Nitrite Removal Capacity of Silicon-Based Carriers in Formulated Aquaculture Water

[0094]

[0095] Example 3: Test on the nitrite removal capacity of a combination of sodium bicarbonate, Bacillus tropicalis powder, and silicon-based carrier in aquaculture water.

[0096] 50L of lake water was placed in an aquarium, and 0.03g of nitrite and 0.015g of ammonium chloride were added. The initial nitrite content was determined based on the spectrophotometric count.

[0097] 1. Set up 9 experimental groups, adding at least two of the following: sodium bicarbonate, silicon-based carrier, and Bacillus tropicalis powder (see Table 3 below for specific combinations; images of the three substances are shown below). Figure 1 As shown in the figure, it was cultured in an incubator at 36°C for 3 days.

[0098] 2. Control group: No substance was applied.

[0099] 3. Take 40 mL of water sample from each experimental group every 24 hours and centrifuge the water sample at 5000 r / min for 5 min.

[0100] 4. Use a multi-parameter water quality analyzer to determine the nitrite content of each water sample. Repeat the measurement three times and record the average value.

[0101] The results of the nitrite content determination are shown in Table 3 below. The results show that the nitrite removal rate of the experimental group with 500g sodium bicarbonate + 100g silicon-based carrier / acre reached 45% after 72 hours, which was the lowest among all experimental groups. The nitrite removal rate of the experimental group with 500g sodium bicarbonate + 200g silicon-based carrier + 200g Bacillus tropicalis powder / acre reached 86% after 72 hours, which was the highest among all experimental groups.

[0102] Table 3. Effects of the combination of sodium bicarbonate, Bacillus tropicalis powder, and silicon-based carrier on the nitrite removal capacity of formulated aquaculture water.

[0103]

[0104] Example 4: Test on the nitrite removal capacity of the combination of sodium bicarbonate, Bacillus tropicalis powder and silicon-based carrier in actual aquaculture water.

[0105] The actual source of the aquaculture water: the aquaculture water of the outer ponds of Litopenaeus vannamei in Nanqiao Town, Fengxian District, Shanghai.

[0106] Addition amount of Bacillus tropicalis powder: 200g / mu, addition amount of silicon-based carrier (calcined silicon dioxide product): 300g / mu, addition amount of sodium bicarbonate: 500g / mu.

[0107] Culture conditions: The culture water in 15L of Litopenaeus vannamei pond was thoroughly mixed. The nitrite content of the actual culture water was determined. 5000mL of the actual culture water was poured into three 5000mL Erlenmeyer flasks, labeled G1, G2, and G3, respectively, as three parallel experimental groups. A mixture of Bacillus tropicalis, silica-based carrier, and sodium bicarbonate (0.0075g) was added to G1, G2, and G3, respectively. 20mL water samples were taken on the first, second, and third days and centrifuged at 5000r / min for 5min. The nitrite content of G1, G2, and G3 was determined according to the procedure of a multi-parameter water quality analyzer.

[0108] The results of the nitrite content determination are shown in Table 4 below. The results show that the combination of 500g sodium bicarbonate + 300g silicon-based carrier + 200g Bacillus tropicalis powder / acre can achieve a maximum nitrite removal rate of 86% in aquaculture water after 72 hours, and the actual application effect is good.

[0109] Table 4. Effects of the combination of sodium bicarbonate, silicon-based carrier, and Bacillus tropicalis powder on the nitrite removal capacity of actual aquaculture water.

[0110]

[0111] In summary, this invention successfully constructs a biological nitrite removal product composed of sodium bicarbonate, a silicon-based carrier, and Bacillus tropicalis powder, and it has the following advantages:

[0112] 1. To achieve efficient and rapid degradation of nitrite, significantly reducing the nitrite content in water bodies to meet safety standards.

[0113] 2. Through the synergistic effect of multiple components, the effective action time of the product in water is extended, preventing nitrite rebound.

[0114] 3. While degrading nitrite, it comprehensively improves the aquatic ecological environment, promotes the growth of beneficial microorganisms, inhibits the reproduction of harmful microorganisms, and enhances the self-purification capacity of the water body.

[0115] 4. Ensure product safety and environmental protection, with no toxicity or residue to aquatic organisms and the environment. Applicable to various scenarios, including aquaculture, drinking water purification, and landscape water body maintenance, providing an economical, efficient, and green solution for nitrite pollution control.

[0116] The successful implementation of this invention will fill a key gap in the preparation and application technology of existing biological nitrite removal products, providing a new and scalable technical path for removing nitrite content in aquaculture water, especially applicable to the field of aquaculture, and has important scientific research value and industrial application prospects.

Claims

1. A tropical Bacillus, characterized in that, The strain, named Bacillus tropicus SHOU-1, is deposited at the China Center for Type Culture Collection (CCTCC) on May 13, 2026, with accession number CCTCC NO: M2026947.

2. A biological nitrite removal product, characterized in that, It comprises the following components: Bacillus tropicalus powder, silicon-based carrier, and sodium bicarbonate; wherein the Bacillus tropicalus is the Bacillus tropicus SHOU-1 strain as described in claim 1.

3. The biological nitrite removal product according to claim 2, characterized in that, The silicon-based carrier is a calcined silicon dioxide product.

4. The biological nitrite removal product according to claim 2, characterized in that, The components of this product, by mass percentage, are: silicon-based carrier 20-30%, Bacillus tropicalis powder 20-25%, and sodium bicarbonate 50-60%.

5. The method for preparing the biological nitrite removal product according to any one of claims 2-4, characterized in that, Includes the following steps: (1) Pretreatment of silicon-based carrier: The silicon-based carrier is cleaned, dried and crushed and ground; (2) Culture and preparation of Bacillus tropicalus powder: The Bacillus tropicus SHOU-1 strain was cultured in a large scale; when the bacterial growth entered the stable period, the bacterial cells were collected and then freeze-dried or spray-dried to prepare Bacillus tropicalus powder; (3) Product mixing and preparation: Mix the pretreated silicon-based carrier, Bacillus tropicalis powder and sodium bicarbonate according to the mass ratio.

6. The preparation method according to claim 5, characterized in that, In step (1), the silicon-based carrier is crushed and ground to 100 mesh.

7. The preparation method according to claim 5, characterized in that, In step (2), the temperature is controlled at 35-40℃ and the time is 8-12h during the extended culture process.

8. The preparation method according to claim 5, characterized in that, In step (2), the culture medium formula for expansion culture is: 5g glucose, 10g soybean meal powder, 2g yeast extract, 1g potassium dihydrogen phosphate, 0.5g magnesium sulfate, and 1000mL distilled water.

9. The application of the tropical Bacillus of claim 1 in the preparation of biological nitrite removal products.

10. The application of the biological nitrite removal product according to any one of claims 2-4 as a nitrite removal agent in aquaculture and wastewater treatment.

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