A nano Fe3O4-microorganism composite nano microbial agent, a preparation method and application thereof

Abstract

The application discloses a kind of nano Fe3O4-microorganism composite nanobacterium agent for high-efficiency degradation of kitchen garbage and its preparation method and application.The application first takes kitchen garbage as inoculation source, successfully enriches the original microorganism with high degradation capacity in the natural degradation process of kitchen garbage, and the enriched microbial flora has the dominant genera of bacillus velezensis, leuconostoc and saccharomyces cerevisiae;Secondly, using nano Fe3O4 as an activator, the microorganism is coupled with nanoparticles to obtain nano Fe3O4-microorganism composite nanobacterium agent;The agent can be applied to kitchen garbage treatment, and under the condition of 15℃-30℃, through stirring and supplementing a certain amount of oxygen, 80%-99% weight loss of kitchen garbage can be realized within 3h-5h, and high-biochemical metabolic liquid products are produced.The application innovatively combines nanomaterials with microorganisms, utilizes the interaction between nanomaterials and microorganisms to accelerate the realization of kitchen garbage reduction, resource utilization and harmlessness target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microbial agent, in particular to a preparation method of nano Fe3O4-microbial composite nano agent and application thereof in efficient degradation of kitchen waste. BACKGROUND

[0002] With the development of the catering industry and the comprehensive implementation of household waste classification, the production of kitchen waste is increasing year by year. In recent years, in order to promote and standardize the development of kitchen waste treatment industry, a series of relevant policies have been issued. The common purpose of the above measures is to realize the harmless treatment and resource utilization of kitchen waste. With the further implementation of the policy, promoting the innovation of kitchen waste treatment technology is an important measure to realize the harmless treatment and resource utilization of kitchen waste.

[0003] Due to the limitation of waste classification system and disposal technology, the current kitchen waste treatment is still mainly landfill and incineration. However, landfill and incineration have the problems of large land occupation, easy secondary pollution of air and groundwater, etc. Compared with the above two traditional treatment methods, biological treatment method has the advantages of low cost, low energy consumption, environmental friendliness, no secondary pollution, etc., which has attracted widespread attention and research, and has shown great application prospect in the field of kitchen waste treatment.

[0004] In order to improve the degradation rate of kitchen waste, adding microbial agent is an effective method. It is of great practical significance and demand to provide a microbial agent with strong pertinence, simple culture, no need for repeated addition and simple application conditions. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a nano Fe3O4-microbial composite nano agent for efficient degradation of kitchen waste and a preparation method and application thereof. The method enriches efficient degradation microbial community from kitchen waste, uses nano Fe3O4 as microbial enhancer to prepare nano Fe3O4-microbial composite nano agent. With the enzyme activity of nano Fe3O4 itself, the degradation activity of microorganisms on kitchen waste is stimulated, so as to promote the efficient and rapid degradation of kitchen waste by microorganisms within 3h~5h at room temperature of 15℃~30℃. The whole process is stable in a certain oxygen environment and does not need repeated addition of nano composite agent.

[0006] The present application provides a preparation method of nano Fe3O4-microbial composite nano agent, which comprises the following steps:

[0007] Step one, enrichment and culture of degradation kitchen waste microbial flora: using kitchen waste / food waste as inoculum, enrichment culture is carried out by using culture medium, shock overnight and centrifugal collection to obtain microbial bodies; wherein the microbial bodies are bacillus velezensis (Bacillus velezensis Leuconostoc mesenteroides (ATCC 8293), and Saccharomyces cerevisiae (ATCC 9080) are dominant genera; Leuconostoc Saccharomyces cerevisiae

[0008] Step two, preparation of nano-Fe3O4-microorganism composite nanobacterium agent: ferrous chloride and ferric chloride are used as iron source, and the iron salts are dissolved in sterile water to obtain an iron salt mixture solution; the iron salt mixture solution is added into an ammonia solution, magnetically stirred, and lactoglobulin is added as a dispersant, and the reaction is carried out for 5-8 h; after magnetic separation, the nano-Fe3O4 is obtained by washing with sterile water and drying; the nano-Fe3O4 is dissolved in a phosphate buffer solution to obtain a nano-Fe3O4 solution; the microbial cells are mixed with the nano-Fe3O4 solution, the concentration of the microbial cells is controlled to be 0.2 g / L-5 g / L, and the incubation is carried out at 30°C and 40 rpm for 1 h, and the nano-Fe3O4-microorganism composite nanobacterium agent is obtained by centrifugal separation.

[0009] Further, in the step one, the inoculum source is kitchen garbage / catering waste placed for 2-3 days, the inoculum amount is 50 g / L-200 g / L, the culture condition is 25°C-35°C, and the shaking parameter is 150 rpm-180 rpm.

[0010] Further, in the microbial cells, the relative content of Bacillus velezensis at the bacterial level is 42%-58%, the relative content of Leuconostoc mesenteroides at the bacterial level is 36%-43%, and the relative content of Saccharomyces cerevisiae at the fungal level is 88%-95%.

[0011] Further, in the step two, the concentration of ferrous chloride is 0.05 mol / L-0.5 mol / L, the concentration of ferric chloride is 0.1 mol / L-1.0 mol / L, the molar ratio between divalent iron and trivalent iron in the iron salt mixture solution is 1:2, the mass fraction of the ammonia solution is 1%-5%, the volume ratio of the iron salt mixture solution to the ammonia solution is 1:5, and the mass fraction of lactoglobulin is 0.5%-2%; the nano-Fe3O4 solution is prepared by dissolving 0.5 g-4 g of the nano-Fe3O4 in 1 L of a phosphate buffer solution.

[0012] Further, in the step two, the ratio of the nano-Fe3O4 to the microbial cells is 0.8-2.25.

[0013] Further, in the step two, the incubation parameters are as follows: the concentration of the microbial cells is 0.2 g / L-5 g / L, the incubation is carried out at 30°C and 40 rpm for 1 h.

[0014] ​​The application also provides the nano Fe3O4-microorganism composite nanobacterium agent prepared by the preparation method of the nano Fe3O4-microorganism composite nanobacterium agent.

[0015] The application also provides application of the nano Fe3O4-microorganism composite nanobacterium agent in the field of degradation of kitchen garbage.

[0016] Further, the degradation method of the kitchen garbage comprises the following steps: mixing the nano Fe3O4-microorganism composite nanobacterium agent and the kitchen garbage, stirring at 40 r / min-60 r / min, controlling the reaction temperature to be 15-30 DEG C, and degrading the kitchen garbage through 3-5 h reaction under the condition of supplementing oxygen by stirring.

[0017] Further, the specific adding amount is as follows: the nano Fe3O4-microorganism composite nanobacterium agent is 0.6-9 g / L, the kitchen garbage is 500-1000 g / L, and the ratio of the nano Fe3O4-microorganism composite nanobacterium agent to the kitchen garbage is 1: (110-840). Cr The BOD5 / COD of the metabolic liquid product is 0.45-0.85.

[0018] Compared with the prior art, the technical scheme provided by the application has at least the following advantages:

[0019] 1) The nano Fe3O4 is a variable valence oxide, has the characteristics of magnetism, conductivity, redox and high specific surface area, is coupled with the high-efficiency degradation microorganism, and is prepared into the microorganism-nano material composite bacterium agent, so that the metabolic characteristics of the microorganism and the characteristics of the nano material can be combined, in the synergistic system formed by the nano Fe3O4 and the high-efficiency degradation microorganism, the nano Fe3O4 can be used as an electron transfer medium to accelerate the electron transfer between microbial species, and can be used as a regulating factor to stimulate microbial activity, and then affect the biological behaviors such as adhesion, proliferation and differentiation of the microorganism; the extracellular secretory substances and accessory structures of the microorganism can make the nano Fe3O4 form a conductive network, break through the limitation of the electron transfer distance between the microorganisms, and realize long-distance electron transfer of the microorganisms. Therefore, under the action of the nano Fe3O4, the nano Fe3O4 can be used as an activator to reconstruct the microbial community degradation system, significantly accelerate the metabolic rate of the microorganism, and effectively solve the problems of reduction, harmlessness and resource utilization in the kitchen garbage treatment industry.

[0020] 2) The used microbial flora is screened from kitchen garbage and has strong pertinence. The dominant bacteria Bacillus velezensis and Saccharomyces cerevisiae can efficiently degrade the main components in kitchen garbage such as starch, protein, fat and cellulose, and quickly convert complex insoluble organic matter into simple soluble monomers or dimers, fatty acids and the like; Leuconostoc as a kind of fermentation bacteria can further convert the soluble monomers or dimers produced in the hydrolysis process into easily degradable organic matter. Especially under the driving of nano Fe3O4, it has the functional activity of nano enzyme, can further realize the chain breaking and complex breaking of hydrolysis products, thereby improving the biodegradability of the hydrolysis products, forming liquid metabolites with high BOD5 / COD Cr (0.45~0.85), thereby improving the resource utilization of the hydrolysis products.

[0021] 3) The preparation method of the microbial-nanometer material composite microbial agent is simple and efficient, and has low cost. The microbial flora can be cultured in classic LB medium, and the culture conditions are simple and easy to expand culture; lactoglobulin is added as a dispersant in the preparation process of nano Fe3O4, and the unique amino acid structure and charged properties of lactoglobulin can induce the formation of sub-10 nm Fe3O4, which has significantly improved activity compared with conventional nano metal oxides.

[0022] 4) In the process of degrading kitchen garbage, the nano composite microbial agent does not need to be fermented and continuously added, and has no limitation and requirement on reaction temperature, and can efficiently degrade at room temperature (15℃~30℃) without additional heat supply. The reaction period is short, and 80%~99% of organic kitchen garbage can be converted into small molecule organic acid liquid metabolites in 3 h~5 h under anoxic or aerobic environment, and the garbage reduction rate is as high as 99%. After the degradation is completed, kitchen garbage can be repeatedly added, and the system can be continuously and stably operated without the need to add the nano composite microbial agent multiple times. DETAILED DESCRIPTION

[0023] The inventors found that, to date, a number of patents have published methods for the preparation and application of microbial agents for the degradation of kitchen waste. Although the microbial agents prepared by these patents have a promoting effect on the degradation of kitchen waste, there are still some problems, such as the source of microorganisms, the cultivation of microorganisms, the compounding method of microbial agents, and the application conditions of microbial agents. In terms of the source of microorganisms, the selected microorganisms are not very targeted. The microorganisms used in most patents are purchased from microbial strain collections (such as patents CN112322517A, CN115058368A, CN114437976, etc.), and a small number are screened from soil and cow dung samples (such as patents CN114574383A and CN114921356A) or earthworm manure (such as patent CN107282593A). Very few original microorganisms are screened from kitchen waste; in terms of microbial cultivation, different microorganisms need to be cultured in different culture media, and the cultivation time is also different, which increases the complexity of the operation; in terms of the compounding method of microbial agents, most patents Some patents simply mix microorganisms (such as patents CN107760616A, CN112481152A, CN112159783A, CN112680385A, etc.), which easily causes microbial loss during the degradation of kitchen waste. A small number of patents use microorganisms in combination with carriers such as coal slag, zeolite, rice bran, bran, pine needle powder, etc. (such as patents CN107282593A, CN102409034A, CN101948756A, CN112111429A, etc.), but fermentation must be carried out before adding kitchen waste, which increases the treatment cycle. In terms of the application conditions of microbial agents, some microbial agents require the use of higher temperatures (40 o C~60 o C) Activating bacterial strains (e.g., patents CN112322517 and CN112481152A), which increases energy consumption. In addition to the four issues mentioned above, there are also issues such as the continuous addition of microbial agents (e.g., patent CN113337429A) or varying oxygen requirements of microorganisms (e.g., patent CN115058368A).

[0024] In view of this, the first aspect of the present invention provides a method for preparing a nano-Fe3O4-microorganism composite nano-bacterial agent, the method comprising the following steps:

[0025] Step 1: Enrichment and cultivation of microbial flora for degrading kitchen waste: using kitchen waste / restaurant waste as inoculation source, enrichment and cultivation are carried out in culture medium, shaking overnight and centrifuging to obtain microbial cells; wherein, the microbial cells are Bacillus velezinis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) is the dominant genus;

[0026] Step two, preparation of nano Fe3O4-microorganism composite nanobacterium agent: ferrous chloride and ferric chloride are used as iron source, and the iron salts are dissolved in sterile water to obtain an iron salt mixture solution;

[0027] The iron salt mixture solution is added to an ammonia solution, magnetically stirred, and lactoglobulin is added as a dispersant, and the reaction is carried out for 5-8 h; after magnetic separation, the product is washed with sterile water and dried to obtain nano Fe3O4 with magnetism;

[0028] The nano Fe3O4 is dissolved in a phosphate buffer solution to obtain a nano Fe3O4 solution;

[0029] The microbial cells are mixed with the nano Fe3O4 solution, the concentration of the microbial cells is controlled to be 0.2 g / L-5 g / L, and the mixture is incubated at 30℃ and 40 rpm for 1 h, and then centrifuged to obtain a nano Fe3O4-microorganism composite nanobacterium agent. It should be noted that after the microbial cells are mixed with the nano Fe3O4 solution, the nano Fe3O4 adheres to the surface of the bacteria or the bacterial appendage structure, and a Fe3O4-microorganism composite nano-ecological community is spontaneously formed. The unique amino acid structure and charged nature of lactoglobulin can induce the formation of sub-10 nm Fe3O4.

[0030] The second aspect of the present application also provides a nano Fe3O4-microorganism composite nanobacterium agent prepared by the preparation method of the nano Fe3O4-microorganism composite nanobacterium agent.

[0031] The third aspect of the present application also provides the use of the nano Fe3O4-microorganism composite nanobacterium agent in the degradation of kitchen waste / food waste.

[0032] Further, the degradation method of the kitchen waste / food waste comprises: mixing the nano Fe3O4-microorganism composite nanobacterium agent and the kitchen waste / food waste, stirring at 40 r / min-60 r / min, controlling the reaction temperature to be 15℃-30℃, and ensuring oxygen supply conditions to complete the degradation after 3 h-5 h of reaction. Specifically, the oxygen supply can be provided by stirring only without aeration. The kitchen waste / food waste can be dynamically added multiple times, and the degradation efficiency can be maintained stable, and the nano Fe3O4-microorganism composite nanobacterium agent does not need to be repeatedly supplemented.

[0033] The present application will be described in detail below with reference to the specific embodiments.

[0034] Example 1

[0035] Take 50 g of kitchen garbage placed for 2 days and add it to 1 L of LB medium, shake at 25°C, 150 rpm overnight. The obtained microbial flora has Bacillus velezensis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) as dominant genera. After enrichment culture, the relative content of Bacillus velezensis and Leuconostoc at the bacterial level is 42% and 36% respectively, and the relative content of Saccharomyces cerevisiae at the fungal level is 88%. Centrifuge to collect microbial cells.

[0036] Dissolve 3.175 g of ferrous chloride and 8.11 g of ferric chloride in 500 mL of sterile water respectively, control the molar ratio of Fe(II) / Fe(III) in the solution system to be 1:2, marked as solution A; then take 500 mL of solution A, add 100 mL of 1% ammonia water solution (solution B), control the volume ratio B:A = 5, fully stir with a magnetic stirrer, add 3 g of lactoglobulin as a dispersant during the reaction, and fully react for 5 h. Obtain magnetic nano Fe3O4 by magnetic separation, then rinse with sterile water and dry. Take 0.5 g of nano Fe3O4 and dissolve it in 1 L of phosphate buffer solution, then add 0.2 g of microbial cells to the nano Fe3O4 solution, control the concentration of microbial cells to be 0.2~5 g / L, incubate at 30°C, 40 rpm for 1 h, nano Fe3O4 adheres to the surface of bacteria or bacterial appendage structure, and Fe3O4-microorganism composite nano ecological community is spontaneously formed. Centrifugal separation can obtain microbial-nano material composite microbial agent.

[0037] In a 1 L container, add 0.6 g of microbial-nano material composite microbial agent and 500 g of kitchen garbage and mix well, without any acclimation time, directly stir at 40 r / min, control the reaction temperature to be 15°C, after 3 h of reaction, the weight loss rate of kitchen garbage is 80%, solid organic matter is converted into liquid organic acid metabolites, and the BOD5 / COD Cr of the metabolic liquid product is 0.45.

[0038] Example 2

[0039] Take 80 g of kitchen garbage placed for 3 days and add it to 1 L of LB medium, shake at 30°C, 160 rpm overnight. The obtained microbial flora has Bacillus velezensis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiaeBacillus velezensis and Leuconostoc were the dominant bacteria, and the relative content of Bacillus velezensis and Leuconostoc was 45% and 40% respectively at the bacterial level, and the relative content of Saccharomyces cerevisiae was 88% at the fungal level after enrichment culture.

[0040] 6.35 g of ferrous chloride and 16.22 g of ferric chloride were weighed and dissolved in 500 mL of sterile water, and the molar ratio of Fe(II) / Fe(III) in the solution system was controlled to be 1:2, denoted as solution A; then 500 mL of solution A was measured, 100 mL of 2% ammonia water solution (solution B) was added, the volume ratio of B:A was controlled to be 5, and a magnetic stirrer was used for sufficient stirring, 3 g of lactoglobulin was added as a dispersant during the stirring, and the reaction was allowed to proceed for 6 h. The magnetic separation was performed, and then the magnetic nano-Fe3O4 was obtained by washing with sterile water and drying. 1 g of nano-Fe3O4 was dissolved in 1 L of phosphate buffer solution, and then 1 g of microbial biomass was mixed with the nano-Fe3O4 solution, the concentration of the microbial biomass was controlled to be 0.2-5 g / L, and the mixture was incubated at 30°C and 40 rpm for 1 h. The nano-Fe3O4 was attached to the surface of the bacteria or the bacterial appendage structure, and the Fe3O4-microorganism composite nano-ecological community was spontaneously formed. The microbial-nano material composite microbial inoculant was obtained by centrifugal separation.

[0041] In a 1 L container, 2 g of the microbial-nano material composite microbial inoculant and 600 g of kitchen waste were mixed, and the mixture was stirred at 45 r / min without any acclimation time. The reaction temperature was controlled to be 20°C, and after 4 h of reaction, the weight loss rate of the kitchen waste was 84%, and the solid organic matter was converted into liquid organic acid metabolites. The BOD5 / COD of the metabolic liquid product B was 0.60. Cr

[0042] Example 3

[0043] 110 g of kitchen waste placed for 2 d was weighed and added to 1 L of LB medium, and the mixture was shaken at 35°C and 170 rpm overnight. The obtained microbial flora had Bacillus velezensis (Bacillus velezensis) as the dominant bacteria, and the relative content of Bacillus velezensis and Leuconostoc was 46% and 38% respectively at the bacterial level, and the relative content of Saccharomyces cerevisiae was 90% at the fungal level after enrichment culture. Bacillus velezensis Leuconostoc Saccharomyces cerevisiae

[0044] ​​​​12.7 g of ferrous chloride and 32.44 g of ferric chloride were weighed and dissolved in 500 mL of sterile water, controlling the Fe(II) / Fe(III) molar ratio to 1:2. This solution, designated Solution A, was then added to 500 mL of Solution A, along with 100 mL of 3% ammonia solution (Solution B), achieving a volume ratio of B:A of 5. The mixture was stirred thoroughly with a magnetic stirrer, and 7 g of lactoglobulin was added as a dispersant. The reaction was allowed to proceed for 6.5 hours. Magnetic separation, followed by rinsing with sterile water and drying, yielded magnetic nano-Fe₃O₄. Weigh 2 g of nano-Fe3O4 and dissolve it in 1 L of phosphate buffer solution. Then add 2 g of microbial cells and mix them with the nano-Fe3O4 solution. The concentration of microbial cells is controlled at 0.2~5 g / L. Incubate at 30℃ and 40 rpm for 1 hour. Nano-Fe3O4 adheres to the bacterial surface or bacterial appendage structure, spontaneously forming a Fe3O4-microorganism composite nano-ecological community. The microbial-nanomaterial composite bacterial agent can be obtained by centrifugation.

[0045] In a 1 L container, 4 g of microbial-nanomaterial composite inoculant and 700 g of kitchen waste were added and fully mixed. No acclimation time was required and the mixture was stirred at 50 r / min. The reaction temperature was controlled at 25 °C. After 5 h of reaction, the weight loss rate of kitchen waste was 95%, and the solid organic matter was converted into liquid organic acid metabolites. The metabolic liquid product BOD5 / COD Cr It is 0.68.

[0046] Example 4

[0047] 140 g of kitchen waste that had been stored for 3 days was weighed and added to 1 L of LB medium. The mixture was shaken at 25°C and 180 rpm overnight. The microbial flora obtained was mainly composed of Bacillus velezensis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) was the dominant bacterial genus. After enrichment culture, the relative contents of Bacillus Velezii and Leuconostoc were 50% and 41% respectively at the bacterial level, and the relative content of Saccharomyces cerevisiae at the fungal level was 89%. The microbial cells were collected by centrifugation.

[0048] 19.05 g of ferrous chloride and 48.66 g of ferric chloride were weighed and dissolved in 500 mL of sterile water, controlling the Fe(II) / Fe(III) molar ratio to 1:2. This solution, designated Solution A, was then added to 500 mL of Solution A, along with 100 mL of 3% ammonia solution (Solution B), achieving a volume ratio of B:A of 5. The mixture was stirred thoroughly with a magnetic stirrer, and 9 g of lactoglobulin was added as a dispersant. The reaction was allowed to proceed for 7 hours. Magnetic separation, followed by rinsing with sterile water and drying, yielded magnetic nano-Fe₃O₄. Weigh 2.5 g of nano-Fe3O4 and dissolve it in 1 L of phosphate buffer solution. Then add 3 g of microbial cells and mix them with the nano-Fe3O4 solution. The concentration of microbial cells is controlled at 0.2~5 g / L. Incubate at 30℃ and 40 rpm for 1 hour. Nano-Fe3O4 adheres to the bacterial surface or bacterial appendage structure, spontaneously forming a Fe3O4-microorganism composite nano-ecological community. The microorganism-nanomaterial composite bacterial agent can be obtained by centrifugation.

[0049] In a 1 L container, 5.5 g of microbial-nanomaterial composite inoculant and 800 g of kitchen waste were added and fully mixed. No acclimation time was required and the mixture was stirred at 55 r / min. The reaction temperature was controlled at 25 °C. After 3 h of reaction, the weight loss rate of kitchen waste was 90%, and the solid organic matter was converted into liquid organic acid metabolites. The metabolic liquid product BOD5 / COD Cr is 0.75.

[0050] Example 5

[0051] Weigh 170 g of kitchen waste that had been stored for 2 days and add it to 1 L of LB medium. Shake overnight at 30°C and 180 rpm. The microbial flora obtained was mainly composed of Bacillus velezensis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) was the dominant bacterial genus. After enrichment culture, the relative contents of Bacillus Velezii and Leuconostoc were 53% and 42% at the bacterial level, respectively, and the relative content of Saccharomyces cerevisiae at the fungal level was 90%. The microbial cells were collected by centrifugation.

[0052] 25.4 g of ferrous chloride and 64.88 g of ferric chloride were weighed and dissolved in 500 mL of sterile water, controlling the Fe(II) / Fe(III) molar ratio to 1:2. This solution, designated Solution A, was then added to 500 mL of Solution A, along with 100 mL of 4% ammonia solution (Solution B), achieving a volume ratio of B:A of 5. The mixture was stirred thoroughly with a magnetic stirrer, and 11 g of lactoglobulin was added as a dispersant. The reaction was allowed to proceed for 7.5 hours. Magnetic separation, followed by rinsing with sterile water and drying, yielded magnetic nano-Fe₃O₄. Weigh 3 g of nano-Fe3O4 and dissolve it in 1 L of phosphate buffer solution. Then add 4 g of microbial cells and mix them with the nano-Fe3O4 solution. The concentration of microbial cells is controlled at 0.2~5 g / L. Incubate at 30℃ and 40 rpm for 1 hour. Nano-Fe3O4 adheres to the bacterial surface or bacterial appendage structure, spontaneously forming a Fe3O4-microorganism composite nano-ecological community. The microorganism-nanomaterial composite bacterial agent can be obtained by centrifugation.

[0053] In a 1 L container, 7 g of microbial-nanomaterial composite inoculant and 900 g of kitchen waste were added and fully mixed. No acclimation time was required and the mixture was stirred at 60 r / min. The reaction temperature was controlled at 20 °C. After 4 h of reaction, the weight loss rate of kitchen waste was 99%, and the solid organic matter was converted into liquid organic acid metabolites. The BOD5 / COD ratio of the metabolic liquid product was 2.34. Cr is 0.80.

[0054] Example 6

[0055] Weigh 200 g of kitchen waste that had been stored for 3 days and add it to 1 L of LB medium. Shake overnight at 35°C and 180 rpm. The microbial flora obtained was mainly composed of Bacillus velezensis ( Bacillus velezensis ), Leuconostoc ( Leuconostoc ) and Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) was the dominant bacterial genus. After enrichment culture, the relative contents of Bacillus Velezii and Leuconostoc were 58% and 43% at the bacterial level, respectively, and the relative content of Saccharomyces cerevisiae at the fungal level was 95%. The microbial cells were collected by centrifugation.

[0056] Take 31.75 g of ferrous chloride and 81.1 g of ferric chloride respectively and dissolve them in 500 mL of sterile water, control the molar ratio of Fe(II) / Fe(III) in the solution system as 1:2, recorded as solution A; then take 500 mL of solution A, add 100 mL of 5% ammonia water solution (solution B), control the volume ratio B:A=5, fully stir with a magnetic stirrer, add 12 g of lactoglobulin as a dispersing agent during the stirring, and fully react for 8 h. Obtain magnetic nano Fe3O4 by magnetic separation, and then rinse and dry with sterile water. Take 4 g of nano Fe3O4 and dissolve it in 1 L of phosphate buffer solution, then add 5 g of microbial cells to mix with the nano Fe3O4 solution, control the concentration of the microbial cells as 0.2~5 g / L, incubate at 30℃, 40 rpm for 1 h, the nano Fe3O4 is attached to the surface of the bacteria or the bacterial appendage structure, and spontaneously forms a Fe3O4-microorganism composite nano ecological community, and obtain the microbial-nano material composite microbial agent by centrifugal separation.

[0057] In a 1 L container, add 9 g of microbial-nano material composite microbial agent and 1000 g of kitchen garbage and mix thoroughly, without any acclimation time, directly stir at 50 r / min, control the reaction temperature at 30℃, after 2 h of reaction, the weight loss rate of the kitchen garbage is 99%, and the solid organic matter is converted into liquid organic acid metabolites, the BOD5 / COD of the metabolic liquid product is 0.85. Cr

[0058] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be limited by the scope defined in the claims.​

Claims

1. A method for preparing a nano Fe3O4-microorganism composite nano bacterial agent, characterized in that: The method comprises the following steps: Step 1: Enrichment and cultivation of microbial flora for degrading kitchen waste: Using kitchen waste / restaurant waste as an inoculum source, enrichment and cultivation are performed in a culture medium, followed by shaking overnight and centrifugation to obtain microbial cells; wherein the microbial cells are dominated by Bacillus velezensis, Leuconostoc and Saccharomyces cerevisiae; Step 2: Preparation of nano-Fe3O4-microorganism composite nano-bacterial agent: using ferrous chloride and ferric chloride as iron sources, dissolving ferrous chloride and ferric chloride in sterile water to obtain an iron salt mixture solution; The iron salt mixture solution is added to an ammonia solution, stirred magnetically, and lactoglobulin is added as a dispersant, and reacted for 5 to 8 hours; after magnetic separation, the mixture is rinsed with sterile water and dried to obtain magnetic nano-Fe3O4; Dissolving the nano-Fe3O4 in a phosphate buffer solution to obtain a nano-Fe3O4 solution; The microbial cells were mixed with a nano-Fe3O4 solution, the concentration of the microbial cells was controlled to be 0.2 g / L to 5 g / L, the mixture was incubated at 30°C and 40 rpm for 1 hour, and the mixture was centrifuged to obtain a nano-Fe3O4-microbial composite nano-bacterial agent; In the step 2, the concentration of ferrous chloride is 0.05 mol / L to 0.5 mol / L, the concentration of ferric chloride is in the range of 0.1 mol / L to 1.0 mol / L, and the molar ratio between divalent iron and trivalent iron in the iron salt mixture solution is 1:2; The mass fraction of the ammonia solution is 1% to 5%, the volume ratio of the iron salt mixture solution to the ammonia solution is 1:5, and the mass fraction of the lactoglobulin is 0.5% to 2%; The nano-Fe3O4 solution is prepared by dissolving 0.5 g to 4 g of the nano-Fe3O4 in 1 L of phosphate buffer solution.

2. The method for preparing the nano Fe3O4-microorganism composite nano bacterial agent according to claim 1, characterized in that: In step 1, the inoculation source is specifically kitchen waste / restaurant waste that has been stored for 2 to 3 days, the inoculation amount is 50 g / L to 200 g / L, the culture conditions are 25° C. to 35° C., and the shaking parameter is 150 rpm to 180 rpm.

3. The preparation method of the nano Fe3O4-microorganism composite nano bacterial agent according to claim 1, characterized in that: Among the microbial cells, the relative content of Bacillus velezensis at the bacterial level is 42% to 58%, the relative content of Leuconostoc at the bacterial level is 36% to 43%, and the relative content of Saccharomyces cerevisiae at the fungal level is 88% to 95%.

4. The preparation method of the nano Fe3O4-microorganism composite nano bacterial agent according to claim 1, characterized in that: In the step 2, the ratio of the nano-Fe3O4 to the microbial cells is 0.8-2.

25.

5. The method for preparing the nano Fe3O4-microorganism composite nano bacterial agent according to claim 1, characterized in that: In the step 2, the incubation parameters are: the concentration of the microbial cells is 0.2 g / L to 5 g / L, and the incubation is carried out at 30° C. and 40 rpm for 1 h.

6. The nano-Fe3O4-microorganism composite nano-bacterial agent prepared by the preparation method of the nano-Fe3O4-microorganism composite nano-bacterial agent according to any one of claims 1 to 5.

7. Use of the nano-Fe3O4-microorganism composite nano-bacterial agent as claimed in claim 6 in the field of degrading kitchen waste / restaurant kitchen waste.

8. The use according to claim 7, characterized in that The method for degrading kitchen waste / restaurant kitchen waste comprises: The nano-Fe3O4-microorganism composite nano-bacterial agent and kitchen waste / restaurant kitchen waste are fully mixed, stirred at 40 r / min~60 r / min, the reaction temperature is controlled at 15°C~30°C, and under the condition of adding a certain amount of oxygen through stirring, the degradation is completed after 3 h~5 h of reaction.

9. The use according to claim 7, characterized in that The specific addition amount is: the nano-Fe3O4-microorganism composite nano-bacterial agent is 0.6 g / L~9 g / L, the kitchen waste / restaurant kitchen waste is 500 g / L~1000 g / L, and the ratio of the nano-Fe3O4-microorganism composite nano-bacterial agent to the kitchen waste / restaurant kitchen waste is 1:(110~840); After the degradation is completed, the weight reduction rate of kitchen waste / restaurant kitchen waste is 80%~99%, and the metabolic liquid product BOD5 / COD Cr It is 0.45~0.85.