A composite biological algaecide and its preparation method and application

Abstract

The present invention relates to a composite biological algaecide, a preparation method thereof and an application thereof. The present invention uses the symbiotic coordination between yeast, Bacillus cereus and Bacillus sphingosine, combined with cellulase, protease and betaine to effectively remove algae in eutrophic water in a short period of time, effectively reduce the COD, ammonia nitrogen and total phosphorus content of the eutrophic water, effectively treat the eutrophic water, and further enhance the biological activity and adaptability of the composite bacteria through the use of carriers composed of chitosan, sodium hydroxymethyl cellulose and starch and auxiliary materials composed of sodium ethylenediaminetetraacetic acid and calcium chloride, so as to maintain a stable and effective algae inhibition effect for a long time.

Description

Technical Field

[0001] The invention belongs to the technical field of biological algaecides, and in particular relates to a composite biological algaecide, a preparation method thereof and an application thereof. Background Art

[0002] With the rapid development of economy and society, a large amount of domestic wastewater or industrial wastewater is discharged, and the eutrophication of water bodies and algal bloom are becoming more and more serious. When algal bloom breaks out, it will seriously damage the local water ecosystem and the surrounding environment, and even threaten aquatic plants and animals.

[0003] At present, the methods for controlling algal blooms generally include physical, chemical and biological methods. Physical methods include ultraviolet, ultrasound, shielding, aeration coagulation, salvage, activated carbon adsorption and other operations, which are very inconvenient. The chemical method mainly controls the reproduction of algae through chemical reagents. Commonly used chemical reagents include organic bromine algaecides, copper salts (copper sulfate, copper chloride), potassium permanganate, etc., which are relatively expensive and have secondary pollution. The biological method is to dissolve algae through bacteria, fungi, etc. in a natural state to control the excessive growth of algae. Among them, the biological method is relatively the most environmentally friendly, but because it achieves algae dissolution through the life activities of bacteria, fungi, etc., the cycle is relatively long, and in order to facilitate the feeding, solid bacterial agents are usually used for feeding. The biological activity and adaptability of the bacteria in the water body vary greatly, and the long-term algae inhibition effect is not good, and it is difficult to use on a large scale. Summary of the invention

[0004] The purpose of the present invention is to provide a composite biological algaecide with high algae removal efficiency and stable long-term algae inhibition effect.

[0005] Another object of the present invention is to provide a method for preparing the composite biological algaecide.

[0006] Another object of the present invention is to provide the use of the composite biological algaecide in the treatment of eutrophic water bodies.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a composite biological algaecide, whose raw materials include composite bacterial fermentation broth, biological enzymes, alkaloids, carriers and auxiliary materials, and the mass ratio of the composite bacterial fermentation broth, biological enzymes, alkaloids, carriers and auxiliary materials is (10~15):(1~4):(1~4):(10~15):1, the composite bacterial fermentation broth consists of Bacillus cereus fermentation broth, Bacillus sphingosine fermentation broth and yeast fermentation broth, the Bacillus cereus is preserved in the China Center for Type Culture Collection-CCTCC, the address of the preservation center is Wuhan University, Wuhan, China, the preservation date is May 27, 2022, the preservation number is CCTCC NO: M2022745, and the classification name is Bacillus cereus Q-12, the Sphingobacillus is deposited in China Center for Type Culture Collection (CCTCC), the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M2022746, and the classification name is Sphingobium sp Q-13, the yeast is deposited in China Center for Type Culture Collection (CCTCC), the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M2022747, and the classification name is Rhodotorula sp . Q-14, the mass ratio of the Bacillus cereus fermentation broth, the Sphingobacillus fermentation broth and the yeast fermentation broth is (2~5):1:(1~3), the biological enzyme is composed of cellulase and protease, the alkaloid is betaine, the carrier is composed of chitosan, sodium hydroxymethyl cellulose and corn starch, and the auxiliary material is composed of sodium ethylenediaminetetraacetic acid and calcium chloride.

[0009] Preferably, the concentration of live bacteria in the Bacillus cereus fermentation broth, the Sphingobacillus fermentation broth and the yeast fermentation broth is ≥ 1×10 10 CFU / mL.

[0010] Preferably, the mass ratio of the cellulase to the protease is (1-3):1.

[0011] Further preferably, the mass ratio of the cellulase to the protease is (1-2):1.

[0012] Preferably, the mass ratio of chitosan, sodium hydroxymethyl cellulose and corn starch is 1:(1-3):(2-5).

[0013] Further preferably, the mass ratio of chitosan, sodium hydroxymethyl cellulose and corn starch is 1:(1-2):(2-3).

[0014] Preferably, the mass ratio of sodium edetate to calcium chloride is 1:(1-3).

[0015] Further preferably, the mass ratio of sodium edetate to calcium chloride is 1:(1-2).

[0016] Preferably, the mass ratio of the Bacillus cereus fermentation broth, the Sphingobacillus fermentation broth and the yeast fermentation broth is (2-3):1:(1-2).

[0017] The second aspect of the present invention provides a method for preparing the composite biological algaecide, comprising mixing the Bacillus cereus fermentation broth, the Sphingobacillus fermentation broth and the yeast fermentation broth to obtain the composite bacterial fermentation broth, then uniformly mixing the composite bacterial fermentation broth with the biological enzyme, the alkaloid, the carrier and the auxiliary materials, and then drying to obtain the composite biological algaecide.

[0018] Preferably, the drying temperature is 40° C. to 60° C., and the water content of the composite biological algaecide after drying is 2% to 10%.

[0019] The third aspect of the present invention provides the use of the composite biological algaecide in treating eutrophic water bodies.

[0020] Preferably, the composite biological algaecide is added to the eutrophic water body, and the addition amount of the composite biological algaecide is 5g / m 3 Water ~30g / m 3 Water body.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] The present invention uses the symbiotic coordination between yeast, Bacillus cereus and Sphingobacillus, combined with biological enzymes and alkaloids to work together, and efficiently removes algae in eutrophic water in a short period of time, while effectively reducing the COD, ammonia nitrogen and total phosphorus contents of the eutrophic water, and effectively treats the eutrophic water. Through the coordinated use of carriers composed of chitosan, sodium hydroxymethyl cellulose and corn starch and auxiliary materials composed of sodium ethylenediaminetetraacetic acid and calcium chloride, the biological activity and adaptability of the composite bacteria are further enhanced, and a stable and effective algae inhibition effect is maintained for a long time.

[0023] In the present invention, Bacillus cereus is deposited in China Center for Type Culture Collection-CCTCC, the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M 2022745, and the classification name is Bacillus cereus Q-12.

[0024] In the present invention, Sphingobacillus is deposited in China Center for Type Culture Collection (CCTCC), the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M 2022746, and the classification name is Sphingobium sp .Q-13.

[0025] In the present invention, the yeast is deposited in China Center for Type Culture Collection-CCTCC, the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M 2022747, and the classification name is Rhodotorula sp .Q-14.

[0026] In the present invention, Bacillus chestnut brown is deposited in China Center for Type Culture Collection-CCTCC, the address of the collection center is Wuhan University, Wuhan, China, the collection date is May 27, 2022, the collection number is CCTCC NO: M 2022748, and the classification name is Bacillus sp .Q-15. DETAILED DESCRIPTION

[0027] Hereinafter, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the description is considered to be exemplary and non-restrictive in nature.

[0028] In order to develop a composite biological algaecide with high algae removal efficiency and stable long-term algae inhibition effect, the inventors of the present application have conducted a lot of research and experimental verification on strain screening and formulation formula components, including the composition and dosage ratio of each component in the formula, and finally obtained the composite biological algaecide of the present application. Partial experiments have proved that the composite biological algaecide of the present invention can achieve an algae removal rate of more than 85% in water bodies with a chlorophyll content of 3.8 mg / L~4.5 mg / L after one feeding for one week, making the Spirogyra in the wetland basically yellow and die, and can also effectively remove COD, ammonia nitrogen and total phosphorus in eutrophic water bodies to achieve water purification. The composite biological algaecide of the present invention not only has better short-term algae removal effect, but also has better and more stable long-term algae inhibition effect. One feeding can effectively inhibit algae for at least 2 months, with low processing cost and no secondary pollution.

[0029] In the present invention, all the raw materials mentioned can be purchased from commercial sources or / and prepared by known means, and unless otherwise specified, all meet the requirements of standard chemical products.

[0030] The experimental methods used in the present invention are all conventional methods unless otherwise specified.

[0031] In the present invention, room temperature refers to 25±5°C.

[0032] In the present invention, the algae removal rate calculation formula is:

[0033] , where I is the algae removal rate; C0 is the chlorophyll a content in the control group on the tth day (mg / L), C tis the chlorophyll a content (mg / L) in the treatment group on day t. The chlorophyll a concentration was determined using the acetone repeated freeze-thaw extraction method (Zhang Rui, 2015), with 3 replicates for each measurement and the average value was taken.

[0034] In the present invention, the COD detection method refers to the standard HJ 828-2017 Determination of Chemical Oxygen Demand of Water Quality Dichromate Method; the ammonia nitrogen detection method refers to the standard HJ535-2009 Determination of Ammonia Nitrogen in Water Quality Nessler Reagent Spectrophotometry. The total phosphorus detection method refers to: potassium persulfate digestion ammonium molybdate spectrophotometry (GB11893-89).

[0035] In the present invention, the preparation method of the fermentation broth of each strain is as follows:

[0036] (1) Strain activation: activate the functional strains Bacillus cereus Q-12, Sphingobium sp Q-13. Bacillus sp . Q-15 was streaked onto the slant of a test tube or onto a plate culture medium (culture medium formula: 5 g / L glucose, 5 g / L peptone, 0.5 g / L beef extract, 3 g / L sodium chloride, 20 g / L agar, pH = 7.2) under sterile conditions and cultured in a constant temperature incubator at 32°C for 24 h. Rhodotorula sp Q-14 was inoculated on the slant of a test tube or a plate culture medium (culture medium formula: glucose 20 g / L, peptone 20 g / L, yeast powder 10 g / L, agar 20 g / L, pH = 6.0) under sterile conditions and cultured in a constant temperature incubator at 30°C for 36 h.

[0037] (2) Preparation of strain seed solution: Pick one loop of functional strain from the test tube slope or plate Bacillus cereus Q-12, Sphingobium sp Q-13. Bacillus sp . The Q-15 colonies were inoculated into 1000mL Erlenmeyer flasks containing 200mL of culture medium (composition of culture medium: 5g / L glucose, 5g / L peptone, 0.5g / L beef extract, 3g / L sodium chloride, pH=7.2), cultured at 30℃ for 12h~18h, and microscopic examination showed that the strain was in the logarithmic growth phase and free of foreign bacteria, which was the first-level seed solution. The strain was transferred to a 50L fermenter under sterile conditions and cultured for 18h~24h. Microscopic examination showed that the strain was in the logarithmic growth phase and free of foreign bacteria, which was the second-level seed solution. Pick out the functional strains from the slant of one ring of test tube or plate. Rhodotorula sp The Q-14 colony was inoculated into a 1000mL Erlenmeyer flask containing 200mL of culture medium (composition of culture medium: 20g / L glucose, 20g / L peptone, 10g / L yeast powder, pH=6.0), and cultured at 30℃ for 18h~24h. Microscopic examination showed that the strain was in the logarithmic growth phase and free of foreign bacteria, which was the first-level seed solution. It was transferred to a 50L fermentation tank under sterile conditions and cultured for 18h~24h. Microscopic examination showed that the strain was in the logarithmic growth phase and free of foreign bacteria, which was the second-level seed solution.

[0038] (3) Preparation of culture materials: Weigh the components of the culture medium (Bacillus cereus Bacillus cereus Q-12 fermentation medium: soluble starch 30g / L, soybean meal 20g / L, dipotassium hydrogen phosphate 2g / L, magnesium sulfate heptahydrate 0.5g / L, calcium chloride 0.1g / L, pH=7.0; yeast Rhodotorula sp . Q-14 fermentation medium: glucose 20g / L, yeast powder 10g / L, peptone 20g / L, sodium chloride 3g / L, pH = 6.0; Sphingobium sp Q-13. Bacillus sp . Q-15 fermentation medium: glucose 5g / L, peptone 5g / L, beef extract 0.5g / L, sodium chloride 3g / L, pH=7.2) and soybean oil defoamer were added to the fermentation tank;

[0039] (4) Fermentation culture: The fermentation system was sterilized by high temperature and high pressure, inoculated, and cultured for 36 h to 48 h at 30-32 °C, pH = 6.0-7.5, and DO ≥ 25%. Microscopic examination was performed to check the growth status of the functional strain and the amount of fermented bacteria (> 10 9 / mL) and / or spore rate level (>90%);

[0040] (5) Fermentation broth concentration: After the fermentation culture is completed, the fermentation broth is concentrated and the bacterial count is determined by the plate colony count method. If the bacterial count is greater than 1×10 11 CFU / mL, and obtain high-density strain fermentation broth.

[0041] For ease of understanding of the present invention, the present invention lists the following examples. Those skilled in the art should understand that the examples are only to help understand the present invention and should not be regarded as specific limitations of the present invention. The following examples and comparative examples are only some typical experimental examples in the development process of the present invention. Example 1

[0042] This embodiment provides a composite biological algaecide, and the preparation method is as follows:

[0043] (1) Mixing the fermentation liquid of Bacillus cereus, the fermentation liquid of Bacillus sphingosine and the fermentation liquid of yeast in a mass ratio of 6:3:3 to prepare a composite bacterial fermentation liquid for later use;

[0044] Mix cellulase and protease in a mass ratio of 3:2 to prepare biological enzyme for later use;

[0045] Chitosan, sodium hydroxymethyl cellulose and corn starch are mixed in a mass ratio of 2:3:5 to prepare a carrier for later use;

[0046] Mix sodium ethylenediaminetetraacetate and calcium chloride in a mass ratio of 2:3 to prepare auxiliary materials for later use;

[0047] (2) The composite bacterial fermentation liquid, biological enzyme, betaine (alkaloid), carrier and auxiliary materials are fully mixed in a mass ratio of 10:2:2:10:1, and dried at 60°C until the water content is less than 6%, thereby obtaining the composite biological algaecide 1. Example 2

[0048] This embodiment provides a composite biological algaecide, which is basically the same as that of Embodiment 1, except that the mass ratio of Bacillus cereus fermentation broth, Sphingobacillus fermentation broth and yeast fermentation broth in the composite bacterial fermentation broth is 5:2:3. Example 3

[0049] The embodiment provides a composite biological algaecide, which is basically the same as the embodiment 1, except that in step (2), the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, the betaine (alkaloid), the carrier, and the auxiliary material is 25:4:4:25:2. Example 4

[0050] This embodiment provides a composite biological algaecide, which is basically the same as that of Embodiment 1, except that in step (2), the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, betaine (alkaloid), the carrier, and the auxiliary material is 43:8:6:40:3.

[0051] Comparative Example 1

[0052] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that the mass ratio of Bacillus cereus fermentation broth, Sphingobacillus fermentation broth and yeast fermentation broth in the composite bacterial fermentation broth is 1:1:1.

[0053] Comparative Example 2

[0054] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that the mass ratio of Bacillus cereus fermentation broth, Sphingobacillus fermentation broth and yeast fermentation broth in the composite bacterial fermentation broth is 6:1:1.

[0055] Comparative Example 3

[0056] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that chestnut brown Bacillus fermentation broth is also added to the composite bacteria fermentation broth, and the mass ratio of Bacillus cereus fermentation broth, Sphingobacillus fermentation broth, yeast fermentation broth and chestnut brown Bacillus fermentation broth is 1:1:1:1.

[0057] Comparative Example 4

[0058] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that no biological enzyme is added in step (2), and the mass ratio of composite bacterial fermentation liquid, betaine (alkaloid), carrier, and auxiliary material is 25:4:25:2.

[0059] Comparative Example 5

[0060] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that betaine is not added in step (2), and the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, the carrier, and the auxiliary material is 25:4:25:2.

[0061] Comparative Example 6

[0062] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that no auxiliary materials are added in step (2), and the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, the betaine (alkaloid), and the carrier is 25:4:4:25.

[0063] Comparative Example 7

[0064] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that in step (2), the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, betaine (alkaloid), the carrier, and the auxiliary material is 30:5:5:70:2.

[0065] Comparative Example 8

[0066] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that in step (2), the mass ratio of the composite bacterial fermentation liquid, the biological enzyme, betaine (alkaloid), the carrier, and the auxiliary material is 70:5:5:30:3.

[0067] Comparative Example 9

[0068] This comparative example provides a composite biological algaecide, which is basically the same as Example 1, except that the fermentation broth of Sphingobacillus is replaced with a commercially available Sphingobacillus strain (strain number: BK-J63539, Shanghai Bo Ke Biotechnology Co., Ltd.) fermentation broth, and the yeast fermentation broth is replaced with a commercially available Rhodotorula yeast strain fermentation broth (strain number: AS2.1034, Shanghai Huzheng Biotechnology Co., Ltd.).

[0069] Comparative Example 10

[0070] This comparative example provides a composite biological algaecide, and the preparation method is as follows:

[0071] (1) Mixing Bacillus cereus fermentation liquid, Bacillus chestnut brown fermentation liquid, yeast fermentation liquid, and sphingobacterium fermentation liquid in a mass ratio of 2:3:2:3 to prepare a composite bacterial fermentation liquid for later use;

[0072] Mix kaolin, diatomaceous earth, rice husk powder and corn flour in a mass ratio of 1:1:5:5 to prepare a carrier for later use;

[0073] Mix sodium lignin sulfonate, glucose and peptone in a mass ratio of 1:3:2 to prepare an auxiliary agent and set it aside.

[0074] (2) The composite bacterial fermentation liquid and the carrier are mixed in a mass ratio of 1:3, and an auxiliary agent is added in an amount of 3% of the total mass of the composite bacterial fermentation liquid. The mixture is fully mixed and dried at 40°C until the water content is less than 6%, thereby obtaining a composite biological algaecide.

[0075] Experiment 1:

[0076] Add 400 mL of algae solution pre-cultured in the laboratory into a 500 mL conical flask (chlorophyll a content of 4.22 mg / L, algae culture solution formula uses BG11 medium: NaNO3 1500 mg / L, K2HPO4 0.04 mg / L, MgSO4·7H2O 0.075 mg / L, CaCl2·2H2O 0.036 mg / L, ammonium ferric citrate 0.006 mg / L, EDTA-2Na 0.001 mg / L, citric acid 0.006 mg / L, A5 solution 0.010 ml / L, pH 7.0-7.2. A5 solution: ZnSO4·7H2O 0.22 g / L, H3BO3 2.86 g / L, MnCl4·4H2O 1.86 g / L, Na2MoO4·2H2O 0.39g / L, CuSO4·5H2O 0.08g / L, Co(NO3)2·6H2O0.05g / L), 13 experimental groups and 1 control group were set up, 2g of the composite biological algaecide of the above embodiments and comparative examples were added to the experimental group, and 2g of sterile water was added to the control group. The samples were cultured at 28°C in an artificial climate chamber with a light intensity of 5000Lx and a light-dark cycle ratio of 12h:12h. After 7 days of culture, the algae removal rate of the composite biological algaecide was tested by sampling. The results are shown in Table 1.

[0077]

[0078] Table 1 shows that the algae removal rates of the composite biological algaecides of the embodiments are all over 85%, and the algae removal effects are significantly better than those of the composite biological algaecides of the comparative examples. Among them, the composite biological algae removal rate of the composite biological algaecide of Example 1 is the highest, reaching 92.91%.

[0079] Experiment 2:

[0080] The composite biological algaecide of Example 1 was added to an artificial wetland containing Spirogyra, and the dosage was 5g of the composite biological algaecide per cubic meter of water. The artificial wetland used for the experiment was located in Kunshan City, Jiangsu Province, China. The wetland type was a surface flow wetland. The experimental time was from April 20 to May 20, 2024. The hydraulic retention time of the artificial wetland was 36 hours. Siberian iris was planted. The test results showed that Spirogyra began to turn yellow 3 days after the addition of the composite biological algaecide (including the day of addition). The Spirogyra basically turned yellow and died 7 days after the addition of the composite biological algaecide (including the day of addition). Until the end of the experiment, no new Spirogyra grew, indicating that the composite biological algaecide of Example 1 had a good removal and inhibition effect on Spirogyra.

[0081] Experiment 3:

[0082] 400 mL of river water (COD was 37 mg / L, ammonia nitrogen was 2.6 mg / L, and total phosphorus was 0.3 mg / L) and 2 mL of algae solution (3.76 mg / L) pre-cultured for one week were added to a 500 mL conical flask. Thirteen experimental groups and one control group were set up. 2 g of the composite biological algaecide of the above embodiments and comparative examples was added to the experimental group, and 2 g of sterile water was added to the control group. The mixture was mixed evenly and cultured at 28 °C in light and dark with a light intensity of 5000 Lx and a light-dark cycle ratio of 12 h:12 h. After 7 days of culture, the chlorophyll a concentration, COD concentration, ammonia nitrogen concentration and total phosphorus concentration of the control and treatment groups were measured. The algae removal rate and the removal rates of COD, ammonia nitrogen and total phosphorus of the algaecide were calculated. The results showed that the chlorophyll a concentration, COD, ammonia nitrogen and total phosphorus concentrations of the algaecide group were significantly lower than those of the control group (Table 2).

[0083]

[0084] The culture was continued for 60 days. During the culture period, 2 mL of algae solution pre-cultured for one week was added to the triangular flask of the experimental group every 15 days, for a total of 3 times. The growth of algae cells in the experimental group was observed on the 60th day. The results showed that the water bodies of the experimental groups to which the composite biological algae removal of Examples 1 to 4 was added were clear and transparent without greening, indicating that there was no algae cell growth. However, in the water bodies of the experimental groups to which the composite biological algae removal of Comparative Examples 1 to 10 was added, a large number of algae cells obviously grew, causing the water bodies to turn green and become turbid.

[0085] The above results show that the composite biological algaecides of Examples 1 to 4 can not only efficiently dissolve algae to make the water clear and transparent, but also effectively remove COD, ammonia nitrogen and total phosphorus in eutrophic water to achieve water purification. Compared with the composite biological algaecide of the comparative example, the composite biological algaecide of the embodiment not only has better short-term algae removal effect, but also has better and more stable long-term algae inhibition effect. One feeding can effectively inhibit algae for at least 2 months, and the treatment cost is relatively lower.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite biological algaecide, characterized in that: The raw materials include composite bacterial fermentation broth, biological enzymes, alkaloids, carriers and auxiliary materials. The mass ratio of the composite bacterial fermentation broth, biological enzymes, alkaloids, carriers and auxiliary materials is (10-15): (1-4): (1-4): (10-15): 1, The composite bacterial fermentation liquid is composed of Bacillus cereus fermentation liquid, Bacillus sphingosine fermentation liquid and yeast fermentation liquid. The Bacillus cereus is deposited in the China Center for Type Culture Collection, the address of which is Wuhan University, Wuhan, China. The deposit date is May 27, 2022, the deposit number is CCTCC NO: M2022745, and the classification name is Bacillus cereus Q-12, The Sphingobacterium sphingosineum is deposited in the China Center for Type Culture Collection, the address of which is Wuhan University, Wuhan, China. The deposit date is May 27, 2022, the deposit number is CCTCC NO: M2022746, and the classification name is Sphingobium sp . Q-13, The yeast is deposited in China Center for Type Culture Collection, the address of which is Wuhan University, Wuhan, China. The deposit date is May 27, 2022, the deposit number is CCTCC NO: M2022747, and the classification name is Rhodotorula sp .Q-14, The mass ratio of the Bacillus cereus fermentation liquid, the Sphingobacillus fermentation liquid and the yeast fermentation liquid is (2-5):1:(1-3), The biological enzyme consists of cellulase and protease, the alkaloid is betaine, the carrier consists of chitosan, sodium hydroxymethyl cellulose and corn starch, and the auxiliary material consists of sodium ethylenediaminetetraacetate and calcium chloride.

2. The composite biological algaecide according to claim 1, characterized in that: The live bacteria concentrations in the Bacillus cereus fermentation broth, the Sphingobacillus fermentation broth and the yeast fermentation broth are all ≥1×10 10 CFU / mL.

3. The composite biological algaecide according to claim 1, characterized in that: The mass ratio of the cellulase to the protease is (1-3):

1.

4. The composite biological algaecide according to claim 1, characterized in that: The mass ratio of chitosan, sodium hydroxymethyl cellulose and corn starch is 1:(1-3):(2-5).

5. The composite biological algaecide according to claim 1, characterized in that: The mass ratio of the sodium ethylenediaminetetraacetate to calcium chloride is 1:(1-3).

6. The composite biological algaecide according to claim 1, characterized in that: The mass ratio of the Bacillus cereus fermentation broth, the Bacillus sphingosine fermentation broth and the yeast fermentation broth is (2-3):1:(1-2).

7. The method for preparing the composite biological algaecide according to any one of claims 1 to 6, characterized in that: The Bacillus cereus fermentation liquid, the Bacillus sphingosine fermentation liquid and the yeast fermentation liquid are mixed to obtain the composite strain fermentation liquid, and then the composite strain fermentation liquid, the biological enzyme, the alkaloid, the carrier and the auxiliary materials are evenly mixed, and then dried to obtain the composite biological algaecide.

8. The method for preparing the composite biological algaecide according to claim 7, characterized in that: The drying temperature is 40° C. to 60° C., and the water content of the composite biological algaecide after drying is 2% to 10%.

9. Use of the composite biological algaecide according to any one of claims 1 to 6 in treating eutrophic water bodies.

10. The use according to claim 9, characterized in that: Adding a composite biological algaecide to the eutrophic water body, wherein the amount of the composite biological algaecide added is 5g / m 3 Water ~30g / m 3 Water body.

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