An efficient water-purifying composite microbial inoculant and its preparation method

Abstract

The present invention relates to a composite microbial agent for efficiently purifying water bodies and a preparation method thereof, belonging to the field of water body purification. The present invention uses diatomite, polyaluminum chloride, ammonium sulfate, glucose, nano-calcium carbonate, bacterial strains and self-made modified chitosan as raw materials to prepare a composite microbial agent for efficiently purifying water bodies. The present invention first prepares a suspension by mixing diatomite, polyaluminum chloride and glucose evenly and then drying it, and then adds bacterial strains, nano-calcium carbonate, ammonium sulfate and modified chitosan to the dried product to obtain a composite microbial agent for efficiently purifying water bodies. The composite microbial agent for efficiently purifying water bodies of the present invention has good flocculation effect, and has good treatment effects on suspended particles, COD, insoluble organic matters and heavy metal ions in sewage, and has good stability, and can be widely applied in the field of water body purification.

Description

Technical Field

[0001] The present invention belongs to the field of water purification, and specifically relates to a composite microbial agent for efficiently purifying water and a preparation method thereof. Background Art

[0002] Microbial water purification technology uses the metabolic activities of microorganisms to convert pollutants such as organic matter, nitrogen, and phosphorus in water into harmless substances, thereby achieving water purification. These microorganisms for purifying water can take insoluble organic matter and soluble low-molecular compounds from sewage as nutrient sources, and through catabolism and anabolism, convert them into harmless substances such as carbon dioxide, water, and nitrogen gas, and treat suspended particles in sewage through flocculation. Microbial water purification technology can rapidly degrade organic pollutants in sewage and does not produce new pollutants during the treatment process, which has important environmental protection significance. However, for urban sewage and industrial sewage polluted by heavy metal ions, the water purification effect of microorganisms will be greatly affected. Heavy metal ions such as cadmium ions, lead ions, and mercury ions have a toxic effect on microorganisms and can inhibit the growth and reproduction of microorganisms. When these heavy metal ions are present in water, they will bind to enzymes and proteins in microbial cells, interfering with the normal metabolic activities of microorganisms, resulting in a sharp reduction in the number of microorganisms and a significant decrease in water purification ability. Based on this, the present invention provides a composite microbial agent for efficiently purifying water and a preparation method thereof. Summary of the Invention

[0003] The purpose of the present invention is to provide a composite microbial agent for efficiently purifying water and a preparation method thereof to solve the problems mentioned in the above background art.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A composite microbial agent for efficiently purifying water, comprising the following raw materials in parts by mass: 24 - 30 parts of diatomaceous earth, 16 - 20 parts of polyaluminum chloride, 4 - 5 parts of ammonium sulfate, 8 - 12 parts of glucose, 10 - 12 parts of nano calcium carbonate, 10 - 12 parts of nitrifying bacteria, 2 - 4 parts of Bacillus, 8 - 10 parts of yeast, 4 - 6 parts of photosynthetic bacteria, 6 - 8 parts of lactic acid bacteria, 2.4 - 3 parts of modified chitosan;

[0006] A preparation method of a composite microbial agent for efficiently purifying water, comprising the following steps:

[0007] First step, weigh each raw material according to the parts by mass: 24 - 30 parts of diatomaceous earth, 16 - 20 parts of polyaluminum chloride, 4 - 5 parts of ammonium sulfate, 8 - 12 parts of glucose, 10 - 12 parts of nano calcium carbonate, 10 - 12 parts of nitrifying bacteria, 2 - 4 parts of Bacillus, 8 - 10 parts of yeast, 4 - 6 parts of photosynthetic bacteria, 6 - 8 parts of lactic acid bacteria, 2.4 - 3 parts of modified chitosan;

[0008] Step 2: Add diatomite, polyaluminum chloride, and glucose into deionized water, and ultrasonically disperse and mix them at room temperature to obtain a suspension.

[0009] Step 3: Dry the suspension obtained in Step 2 to constant weight, and then add nitrifying bacteria, bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano calcium carbonate, ammonium sulfate, and modified chitosan to the dried product, and ultrasonically oscillate and mix them at room temperature to obtain a composite microbial agent for highly efficient water purification.

[0010] Further, the time condition for ultrasonic dispersion in Step 2 is 20 - 30 min.

[0011] Further, the time condition for ultrasonic oscillation in Step 3 is 60 - 90 min.

[0012] Further, the modified chitosan is prepared by the following steps:

[0013] Step 1: Mix methyl pyrazine-2-acetate, N-bromosuccinimide, p-toluenesulfonic acid, and acetonitrile in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, raise the system temperature to 60 - 70 °C, and react for 2 h at 60 - 70 °C. After the reaction, add ether to the three-necked flask, wash it successively with saturated sodium carbonate solution and saturated sodium chloride solution, and then separate the organic layer with a separatory funnel. After the organic layer is rotary evaporated to remove the solvent, intermediate 1 is obtained by silica gel column chromatography.

[0014] Step 2: Under ice-water bath conditions, mix 2-pyrazinylethanethiol, potassium carbonate, and absolute ethanol in a three-necked flask, turn on magnetic stirring, and then dropwise add the absolute ethanol solution of intermediate 1 to the three-necked flask over 0.5 h. After the addition is complete, remove the ice-water bath and react at room temperature for 3 h. After the reaction, rotary evaporate the reaction solution to remove the solvent, and then obtain intermediate 2 by silica gel column chromatography.

[0015] Step 3: Mix intermediate 2, ethanol solution, and sodium hydroxide in a three-necked flask, turn on magnetic stirring, and react at room temperature for 3 h. After the reaction, add dilute hydrochloric acid dropwise to the three-necked flask to adjust the pH to 3 - 4, then add ethyl acetate to the three-necked flask for extraction, and separate the organic layer with a separatory funnel. After rotary evaporation of the organic layer, intermediate 3 is obtained.

[0016] Step 4: Mix intermediate 3, chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dilute hydrochloric acid in a three-necked flask, turn on magnetic stirring, and react at room temperature for 48 h. After the reaction, rotary evaporate the reaction solution and pour it into absolute ethanol for precipitation, then vacuum filter. The obtained solid is dried to obtain the chitosan.

[0017] Furthermore, the dosage ratio of methyl pyrazine-2-acetate, N-bromosuccinimide, p-toluenesulfonic acid, and acetonitrile used in Step 1 is 0.1 mol: 0.08 - 0.1 mol: 0.02 mol: 60 - 80 mL.

[0018] Furthermore, the absolute ethanol solution of Intermediate 1 used in Step 2 is prepared from 0.06 mol of Intermediate 1 and 40 mL of absolute ethanol.

[0019] Furthermore, the dosage ratio of 2-pyrazinylethanethiol, potassium carbonate, absolute ethanol, and the absolute ethanol solution of Intermediate 1 used in Step 2 is 0.06 mol: 0.1 - 0.12 mol: 60 - 80 mL: 45.46 g.

[0020] Furthermore, the ethanol solution used in Step 3 is an aqueous ethanol solution with a volume fraction of 75%.

[0021] Furthermore, the dosage ratio of Intermediate 2, ethanol solution, and sodium hydroxide used in Step 3 is 0.04 mol: 50 - 60 mL: 0.06 - 0.08 mol.

[0022] Furthermore, the dilute hydrochloric acid used in Step 4 is dilute hydrochloric acid with a pH value of 4.5.

[0023] Furthermore, the dosage ratio of Intermediate 3, chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dilute hydrochloric acid used in Step 4 is 0.02 mol: 10 g: 6 - 7 g: 3 - 3.5 g: 120 mL.

[0024] Furthermore, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride to N-hydroxysuccinimide used in Step 4 is 2:1.

[0025] Advantages of the present invention:

[0026] 1) The present invention uses diatomite, polyaluminum chloride, ammonium sulfate, glucose, nano calcium carbonate, bacterial strains, and self-made modified chitosan as raw materials to prepare a composite microbial agent for highly efficient water purification. In the present invention, diatomite, polyaluminum chloride, and glucose are first formulated into a suspension, uniformly mixed, and then dried. Subsequently, bacterial strains, nano calcium carbonate, ammonium sulfate, and modified chitosan are added to the dried product to obtain a composite microbial agent for highly efficient water purification. The preparation method of the present invention is simple, easy to scale up, and the prepared composite microbial agent has good flocculation effect, can effectively adsorb fine suspended particles in water, and has good stability.

[0027] 2) Using methyl pyrazine-2-acetate as a raw material, N-bromosuccinimide as a brominating agent, under the catalysis of p-toluenesulfonic acid, the α-hydrogen atom of methyl pyrazine-2-acetate undergoes a halogenation reaction to obtain intermediate 1. Then, using intermediate 1 and 2-pyrazinylethanethiol as raw materials, the bromine atom of intermediate 1 and 2-pyrazinylethanethiol undergo a nucleophilic substitution reaction to obtain intermediate 2. Next, the ester group of intermediate 2 is hydrolyzed in a strongly basic environment to obtain intermediate 3 containing a carboxyl group. Finally, the carboxyl group of intermediate 3 and the amino group of chitosan undergo an amidation reaction under the catalysis of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to be grafted onto chitosan to obtain a modified chitosan; chitosan has good flocculation effect. Through its modification, intermediate 3 with good coordination ability is grafted onto chitosan. Intermediate 3 has multiple nitrogen atom coordination sites and sulfur atom coordination sites, and can play a good coordination and adsorption role on heavy metal ions such as lead ions, mercury ions, and cadmium ions in water. The modified chitosan not only has a good flocculation effect but also has good heavy metal ion adsorption ability, which can greatly improve the purification effect of water bodies.

[0028] 3) An efficient water purification composite microbial agent of the present invention has good flocculation effect, and has good treatment effects on suspended particles, COD, poorly soluble organic matters, and heavy metal ions in sewage, and has good stability, and can be widely applied in the field of water purification. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] Example 1, a modified chitosan, is prepared by the following steps:

[0031] Step 1: Mix 0.1 mol of methyl pyrazine-2-acetate, 0.08 mol of N-bromosuccinimide, 0.02 mol of p-toluenesulfonic acid, and 60 mL of acetonitrile in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, raise the temperature of the system to 60 °C, and react at 60 °C for 2 h. After the reaction is completed, add ether to the three-necked flask, and then wash it successively with saturated sodium carbonate solution and saturated sodium chloride solution. Then, separate the organic layer with a separatory funnel. After the organic layer is rotary evaporated to remove the solvent, intermediate 1 is obtained by silica gel column chromatography;

[0032] Step 2: Under ice-water bath conditions, 0.06 mol of 2-pyrazinylethanethiol, 0.1 mol of potassium carbonate, and 60 mL of absolute ethanol were mixed in a three-necked flask. Magnetic stirring was started, and then a solution prepared from 0.06 mol of intermediate 1 and 40 mL of absolute ethanol (45.46 g) was added dropwise to the three-necked flask over 0.5 h. After the addition was complete, the ice-water bath was removed, and the reaction was carried out at room temperature for 3 h. After the reaction ended, the solvent in the reaction solution was removed by rotary evaporation, and intermediate 2 was obtained by silica gel column chromatography;

[0033] Step 3: 0.04 mol of intermediate 2, 50 mL of an ethanol aqueous solution with a volume fraction of 75%, and 0.06 mol of sodium hydroxide were mixed in a three-necked flask. Magnetic stirring was started, and the reaction was carried out at room temperature for 3 h. After the reaction ended, dilute hydrochloric acid was added dropwise to the three-necked flask to adjust the pH to 3. Then, ethyl acetate was added to the three-necked flask for extraction, and the organic layer was separated with a separatory funnel. The organic layer was rotary evaporated to obtain intermediate 3;

[0034] Step 4: 0.02 mol of intermediate 3, 10 g of chitosan, 6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 3 g of N-hydroxysuccinimide, and 120 mL of dilute hydrochloric acid with a pH of 4.5 were mixed in a three-necked flask. Magnetic stirring was started, and the reaction was carried out at room temperature for 48 h. After the reaction ended, the reaction solution was rotary evaporated and then poured into absolute ethanol for precipitation. Then, vacuum filtration was carried out, and the obtained solid was dried to obtain the chitosan.

[0035] Example 2. A modified chitosan was prepared by the following steps:

[0036] Step 1: 0.1 mol of methyl pyrazine-2-acetate, 0.09 mol of N-bromosuccinimide, 0.02 mol of p-toluenesulfonic acid, and 70 mL of acetonitrile were mixed in a three-necked flask. A condenser and a thermometer were installed, and magnetic stirring was started. After the system temperature was raised to 65 °C, the reaction was carried out at 65 °C for 2 h. After the reaction ended, diethyl ether was added to the three-necked flask, and then it was washed successively with saturated sodium carbonate solution and saturated sodium chloride solution. Then, the organic layer was separated with a separatory funnel. The solvent in the organic layer was removed by rotary evaporation, and intermediate 1 was obtained by silica gel column chromatography;

[0037] Step 2: Under ice-water bath conditions, 0.06 mol of 2-pyrazinylethanethiol, 0.11 mol of potassium carbonate, and 70 mL of absolute ethanol were mixed in a three-necked flask. Magnetic stirring was started, and then a solution prepared from 0.06 mol of intermediate 1 and 40 mL of absolute ethanol (45.46 g) was added dropwise to the three-necked flask over 0.5 h. After the addition was complete, the ice-water bath was removed, and the reaction was carried out at room temperature for 3 h. After the reaction ended, the solvent in the reaction solution was removed by rotary evaporation, and intermediate 2 was obtained by silica gel column chromatography;

[0038] Step 3: Mix 0.04 mol of intermediate 2, 55 mL of an aqueous ethanol solution with a volume fraction of 75%, and 0.07 mol of sodium hydroxide in a three-necked flask. Start magnetic stirring and react for 3 h at room temperature. After the reaction is completed, add dilute hydrochloric acid dropwise to the three-necked flask to adjust the pH to 3.5. Then add ethyl acetate to the three-necked flask for extraction, and separate the organic layer with a separatory funnel. After rotary evaporation of the organic layer, intermediate 3 is obtained;

[0039] Step 4: Mix 0.02 mol of intermediate 3, 10 g of chitosan, 6.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 3.25 g of N-hydroxysuccinimide, and 120 mL of dilute hydrochloric acid with a pH value of 4.5 in a three-necked flask. Start magnetic stirring and react for 48 h at room temperature. After the reaction is completed, rotary evaporate the reaction solution and pour it into absolute ethanol for precipitation. Then perform vacuum filtration. The obtained solid is dried to obtain the chitosan.

[0040] Example 3. A modified chitosan is prepared by the following steps:

[0041] Step 1: Mix 0.1 mol of methyl pyrazine-2-acetate, 0.1 mol of N-bromosuccinimide, 0.02 mol of p-toluenesulfonic acid, and 80 mL of acetonitrile in a three-necked flask. Install a condenser and a thermometer, start magnetic stirring, and raise the temperature of the system to 70 °C. Then react at 70 °C for 2 h. After the reaction is completed, add diethyl ether to the three-necked flask, and wash it successively with saturated sodium carbonate solution and saturated sodium chloride solution. Then separate the organic layer with a separatory funnel. After rotary evaporation of the solvent from the organic layer, intermediate 1 is obtained through silica gel column chromatography;

[0042] Step 2: Under an ice-water bath condition, mix 0.06 mol of 2-pyrazinylethanethiol, 0.12 mol of potassium carbonate, and 80 mL of absolute ethanol in a three-necked flask. Start magnetic stirring, and then add dropwise a solution prepared from 0.06 mol of intermediate 1 and 40 mL of absolute ethanol, with a dropwise addition time of 0.5 h. After the dropwise addition is completed, remove the ice-water bath and react at room temperature for 3 h. After the reaction is completed, rotary evaporate the solvent from the reaction solution and obtain intermediate 2 through silica gel column chromatography;

[0043] Step 3: Mix 0.04 mol of intermediate 2, 60 mL of an aqueous ethanol solution with a volume fraction of 75%, and 0.08 mol of sodium hydroxide in a three-necked flask. Start magnetic stirring and react for 3 h at room temperature. After the reaction is completed, add dilute hydrochloric acid dropwise to the three-necked flask to adjust the pH to 4. Then add ethyl acetate to the three-necked flask for extraction, and separate the organic layer with a separatory funnel. After rotary evaporation of the organic layer, intermediate 3 is obtained;

[0044] Step 4: Mix 0.02 mol of intermediate 3, 10 g of chitosan, 7 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 3.5 g of N-hydroxysuccinimide, and 120 mL of dilute hydrochloric acid with a pH value of 4.5 in a three-necked flask. Start magnetic stirring and react at room temperature for 48 h. After the reaction is completed, rotary evaporate the reaction solution and pour it into absolute ethanol for precipitation. Then, perform vacuum filtration. The obtained solid is dried to obtain the chitosan.

[0045] Comparative Example 1, this comparative example is unmodified chitosan.

[0046] Perform a metal ion adsorption capacity test on the modified chitosan obtained in Examples 1-3 and unmodified chitosan together. Weigh equal masses of the modified chitosan and chitosan and place them in wastewater containing cadmium ions (Cd 2+ ) at room temperature to test the adsorption capacity. Among them, the pH value of the wastewater is 6, the concentration of cadmium ions is 40 mg / L, and the adsorption time is 120 min. The test results are shown in Table 1:

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, the modified chitosan of the present invention in Examples 1-3 has a much better adsorption effect on cadmium ions than unmodified chitosan, indicating that the modified chitosan of the present invention has a good adsorption effect on heavy metal ions.

[0050] Example 4, a composite microbial agent for efficiently purifying water body, comprising the following raw materials in parts by mass: 24 parts of diatomite, 16 parts of polyaluminum chloride, 4 parts of ammonium sulfate, 8 parts of glucose, 10 parts of nano-calcium carbonate, 10 parts of nitrifying bacteria, 2 parts of Bacillus, 8 parts of yeast, 4 parts of photosynthetic bacteria, 6 parts of lactic acid bacteria, and 2.4 parts of the modified chitosan obtained in Example 1;

[0051] A preparation method of a composite microbial agent for efficiently purifying water body, comprising the following steps:

[0052] First step: Weigh each raw material according to 24 parts of diatomite, 16 parts of polyaluminum chloride, 4 parts of ammonium sulfate, 8 parts of glucose, 10 parts of nano-calcium carbonate, 10 parts of nitrifying bacteria, 2 parts of Bacillus, 8 parts of yeast, 4 parts of photosynthetic bacteria, 6 parts of lactic acid bacteria, and 2.4 parts of the modified chitosan obtained in Example 1 in parts by mass;

[0053] Second step: Add diatomite, polyaluminum chloride, and glucose to deionized water, and ultrasonically disperse and mix at room temperature for 20 min to obtain a suspension;

[0054] Step 3: After drying the suspension obtained in Step 2 to constant weight, add nitrifying bacteria, bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano-calcium carbonate, ammonium sulfate, and the modified chitosan obtained in Example 1 to the dried product, and ultrasonically oscillate and mix for 60 min at room temperature to obtain a compound microbial agent for efficiently purifying water body.

[0055] Example 5. A compound microbial agent for efficiently purifying water body, comprising the following raw materials in parts by mass: 27 parts of diatomite, 18 parts of polyaluminum chloride, 4.5 parts of ammonium sulfate, 10 parts of glucose, 11 parts of nano-calcium carbonate, 11 parts of nitrifying bacteria, 3 parts of bacillus, 9 parts of yeast, 5 parts of photosynthetic bacteria, 7 parts of lactic acid bacteria, and 2.7 parts of the modified chitosan obtained in Example 2;

[0056] A preparation method of a compound microbial agent for efficiently purifying water body, comprising the following steps:

[0057] Step 1: Weigh each raw material according to the following parts by mass: 27 parts of diatomite, 18 parts of polyaluminum chloride, 4.5 parts of ammonium sulfate, 10 parts of glucose, 11 parts of nano-calcium carbonate, 11 parts of nitrifying bacteria, 3 parts of bacillus, 9 parts of yeast, 5 parts of photosynthetic bacteria, 7 parts of lactic acid bacteria, and 2.7 parts of the modified chitosan obtained in Example 2;

[0058] Step 2: Add diatomite, polyaluminum chloride, and glucose to deionized water, and ultrasonically disperse and mix for 25 min at room temperature to obtain a suspension;

[0059] Step 3: After drying the suspension obtained in Step 2 to constant weight, add nitrifying bacteria, bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano-calcium carbonate, ammonium sulfate, and the modified chitosan obtained in Example 2 to the dried product, and ultrasonically oscillate and mix for 75 min at room temperature to obtain a compound microbial agent for efficiently purifying water body.

[0060] Example 6. A compound microbial agent for efficiently purifying water body, comprising the following raw materials in parts by mass: 30 parts of diatomite, 20 parts of polyaluminum chloride, 5 parts of ammonium sulfate, 12 parts of glucose, 12 parts of nano-calcium carbonate, 12 parts of nitrifying bacteria, 4 parts of bacillus, 10 parts of yeast, 6 parts of photosynthetic bacteria, 8 parts of lactic acid bacteria, and 3 parts of the modified chitosan obtained in Example 3;

[0061] A preparation method of a compound microbial agent for efficiently purifying water body, comprising the following steps:

[0062] Step 1: Weigh each raw material according to the following parts by mass: 30 parts of diatomite, 20 parts of polyaluminum chloride, 5 parts of ammonium sulfate, 12 parts of glucose, 12 parts of nano-calcium carbonate, 12 parts of nitrifying bacteria, 4 parts of bacillus, 10 parts of yeast, 6 parts of photosynthetic bacteria, 8 parts of lactic acid bacteria, and 3 parts of the modified chitosan obtained in Example 3;

[0063] Step 2: Add diatomite, polyaluminum chloride, and glucose into deionized water, and ultrasonically disperse and mix them for 30 min at room temperature to obtain a suspension.

[0064] Step 3: Dry the suspension obtained in Step 2 to a constant weight, and then add nitrifying bacteria, bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano calcium carbonate, ammonium sulfate, and the modified chitosan obtained in Example 3 into the dried product, and ultrasonically oscillate and mix them for 90 min at room temperature to obtain a composite microbial agent for efficiently purifying water body.

[0065] Comparative Example 2: A composite microbial agent for efficiently purifying water body, comprising the following raw materials in parts by mass: 30 parts of diatomite, 20 parts of polyaluminum chloride, 5 parts of ammonium sulfate, 12 parts of glucose, 12 parts of nano calcium carbonate, 12 parts of nitrifying bacteria, 4 parts of bacillus, 10 parts of yeast, 6 parts of photosynthetic bacteria, 8 parts of lactic acid bacteria, and 3 parts of chitosan.

[0066] A preparation method of a composite microbial agent for efficiently purifying water body, comprising the following steps:

[0067] Step 1: Weigh each raw material according to 30 parts of diatomite, 20 parts of polyaluminum chloride, 5 parts of ammonium sulfate, 12 parts of glucose, 12 parts of nano calcium carbonate, 12 parts of nitrifying bacteria, 4 parts of bacillus, 10 parts of yeast, 6 parts of photosynthetic bacteria, 8 parts of lactic acid bacteria, and 3 parts of chitosan in parts by mass.

[0068] Step 2: Add diatomite, polyaluminum chloride, and glucose into deionized water, and ultrasonically disperse and mix them for 30 min at room temperature to obtain a suspension.

[0069] Step 3: Dry the suspension obtained in Step 2 to a constant weight, and then add nitrifying bacteria, bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano calcium carbonate, ammonium sulfate, and chitosan into the dried product, and ultrasonically oscillate and mix them for 90 min at room temperature to obtain a composite microbial agent for efficiently purifying water body.

[0070] Comparative Example 3: This comparative example is a commercially available microbial carrier adsorption water purifying agent.

[0071] The performance tests were separately conducted on a highly efficient water-purifying composite microbial agent in Examples 4-6 and Comparative Example 2 and a commercially available microbial carrier adsorption water-purifying agent in Comparative Example 3. Equal amounts of the water-purifying agents were respectively placed into urban domestic sewage contaminated by heavy metals, and the COD removal rate in the water was determined with reference to the national standard HJ 828-2017 "Water Quality - Determination of Chemical Oxygen Demand - Dichromate Method", the suspended solid removal rate in the water was tested with reference to the national standard GB / T 11901-1989 "Water Quality - Determination of Suspended Solids - Gravimetric Method", and the ammonia nitrogen removal rate in the water was determined with reference to the national standard HJ 536-2009 "Water Quality - Determination of Ammonia Nitrogen - Salicylic Acid Spectrophotometric Method". The test results are shown in Table 2:

[0072] Table 2

[0073]

[0074] As can be seen from Table 2, the highly efficient water-purifying composite microbial agent in Examples 4-6 of the present invention has a much better purification effect on sewage contaminated by heavy metals than the commercially available microbial carrier adsorption water-purifying agent in Comparative Example 3. Comparative Example 2 conducted a control experiment on the modified chitosan used in the present invention. The absence of the modified chitosan of the present invention will lead to a decline in the purification effect on water bodies contaminated by heavy metals. The reason is that heavy metal ions in the water have a toxic effect on microorganisms. In summary, the highly efficient water-purifying composite microbial agent of the present invention has a good purification effect on sewage and can be widely applied in the field of water purification.

[0075] The above has provided a detailed introduction to a highly efficient water-purifying composite microbial agent and its preparation method of the present invention. Specific examples are used herein to elaborate on the principle and implementation mode of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and modifications can be made to the present invention without departing from the principle of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be combined with each other in any way. The reason for not exhaustively describing the situations of these combinations in this specification is only to save space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A highly efficient composite microbial agent for purifying water, characterized in that: The invention comprises the following raw materials in parts by weight: 24-30 parts of diatomaceous earth, 16-20 parts of polyaluminium chloride, 4-5 parts of ammonium sulfate, 8-12 parts of glucose, 10-12 parts of nano-calcium carbonate, 10-12 parts of nitrifying bacteria, 2-4 parts of bacillus, 8-10 parts of yeast, 4-6 parts of photosynthetic bacteria, 6-8 parts of lactic acid bacteria and 2.4-3 parts of modified chitosan; Wherein, the modified chitosan is prepared by the following steps: Step 1, methyl pyrazine-2-acetate, N-bromosuccinimide, p-toluenesulfonic acid and acetonitrile are mixed in a container, stirred evenly, the system temperature is raised to 60-70° C., and reacted at 60-70° C. for 2 h to obtain intermediate 1; Step 2, 2-pyrazinylethanethiol, potassium carbonate and anhydrous ethanol were mixed in a container under ice-water bath conditions, and after stirring, anhydrous ethanol solution of intermediate 1 was added dropwise to the container for 0.5 h. After the addition was completed, the ice-water bath was removed, and the reaction was carried out at room temperature for 3 h to obtain intermediate 2; Step 3, intermediate 2, ethanol solution and sodium hydroxide are mixed in a container, stirred evenly, and reacted at room temperature for 3 hours. After the reaction is completed, dilute hydrochloric acid is added dropwise to a three-necked flask to adjust the pH to 3-4 to obtain intermediate 3; Step 4, mixing the intermediate 3, chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and dilute hydrochloric acid in a container, stirring evenly, and reacting at room temperature for 48 hours to obtain the chitosan; Intermediate 3 has multiple nitrogen atom coordination sites and sulfur atom coordination sites.

2. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The amount ratio of pyrazine-2-acetic acid methyl ester, N-bromosuccinimide, p-toluenesulfonic acid and acetonitrile used in step 1 is 0.1 mol: 0.08-0.1 mol: 0.02 mol: 60-80 mL.

3. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The anhydrous ethanol solution of intermediate 1 used in step 2 is prepared from 0.06 mol of intermediate 1 and 40 mL of anhydrous ethanol.

4. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The amount ratio of 2-pyrazinylethanethiol, potassium carbonate, anhydrous ethanol, and anhydrous ethanol solution of intermediate 1 used in step 2 is 0.06 mol: 0.1-0.12 mol: 60-80 mL: 45.46 g.

5. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The ethanol solution used in step 3 is an ethanol aqueous solution with a volume fraction of 75%, and the amount ratio of the intermediate 2, the ethanol solution, and the sodium hydroxide used is 0.04 mol: 50-60 mL: 0.06-0.08 mol.

6. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The dilute hydrochloric acid used in step 4 is a dilute hydrochloric acid with a pH value of 4.5, and the amount ratio of the intermediate 3, chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dilute hydrochloric acid used is 0.02 mol: 10 g: 6-7 g: 3-3.5 g: 120 mL.

7. The highly efficient composite microbial agent for purifying water according to claim 1, characterized in that: The mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide used in step 4 is 2:

1.

8. The method for preparing a highly efficient composite microbial agent for purifying water according to any one of claims 1 to 7, characterized in that: The following steps are involved: The first step is to weigh the raw materials according to the mass proportions: 24-30 parts of diatomaceous earth, 16-20 parts of polyaluminium chloride, 4-5 parts of ammonium sulfate, 8-12 parts of glucose, 10-12 parts of nano-calcium carbonate, 10-12 parts of nitrifying bacteria, 2-4 parts of bacillus, 8-10 parts of yeast, 4-6 parts of photosynthetic bacteria, 6-8 parts of lactic acid bacteria, and 2.4-3 parts of modified chitosan; Step 2: adding diatomaceous earth, polyaluminium chloride and glucose into deionized water, and mixing by ultrasonic dispersion at room temperature to obtain a suspension; The third step is to dry the suspension obtained in the second step to constant weight, add nitrifying bacteria, Bacillus, yeast, photosynthetic bacteria, lactic acid bacteria, nano-calcium carbonate, ammonium sulfate and modified chitosan to the dry product, and mix by ultrasonic oscillation at room temperature to obtain a highly efficient composite microbial agent for purifying water.

9. The method for preparing a highly efficient composite microbial agent for purifying water according to claim 8, characterized in that: The time condition of ultrasonic dispersion in the second step is 20-30min.

10. The method for preparing a highly efficient composite microbial agent for purifying water according to claim 8, characterized in that: The time condition of ultrasonic oscillation in the third step is 60-90 minutes.

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