Method for preparing fertilizer from amino acid in high-purity tryptophan fermentation waste liquid

Abstract

The invention discloses a method for preparing a fertilizer from amino acid in high-purity tryptophan fermentation waste liquid, and relates to the technical field of fertilizer preparation, and the method comprises the steps of pretreatment of the tryptophan fermentation waste liquid, amino acid enrichment, nutrition blending and post-treatment operation. The method has the advantages that the high-purity tryptophan fermentation waste liquid is used as a raw material to prepare the fertilizer, various nutritional ingredients in the waste liquid are fully utilized, wastes which originally possibly cause environmental pollution are converted into valuable resources, the problem of treatment of the fermentation waste liquid is solved, environmental pollution is reduced, and the method is suitable for industrial production. Meanwhile, effective recycling of resources is achieved, cross-flow filtration is conducted on the tryptophan fermentation waste liquid through a specially-treated polymer film under the mild condition, macromolecular impurities can be effectively intercepted, amino acid is prevented from being damaged due to high temperature, high pressure or chemical action in the separation process, and the separation efficiency is improved. The composite ion exchange resin column is strictly transformed and flushed, and then is subjected to ion exchange at a proper temperature.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizer preparation, in particular to a method for preparing fertilizer by using amino acids in high-purity tryptophan fermentation waste liquid. Background Art

[0002] With the growth of the global population and the continuous expansion of agricultural production, the demand for fertilizers is increasing. At the same time, the rapid development of the biotechnology field has made the fermentation industry one of the important industries. Tryptophan fermentation is one of the important branches. During the tryptophan fermentation process, a large amount of tryptophan fermentation liquid will be produced. Tryptophan is an amino acid that is of key significance to biological systems. In plant physiology, it is a precursor substance for the synthesis of auxin. Auxin is essential for plant growth and development. It can regulate the elongation, division and differentiation of plant cells, and affect the formation and development of plant roots, stem elongation, leaf expansion and fruit development. This means that tryptophan has potential important value in promoting plant growth and improving crop yield and quality. In animals, tryptophan is one of the essential amino acids. It participates in a variety of physiological functions, including protein synthesis, neurotransmitter synthesis, etc., and is indispensable for maintaining the normal physiological functions and health status of animals. Tryptophan fermentation broth is a by-product of tryptophan fermentation production. It is rich in a variety of nutrients. In addition to tryptophan, it also contains other amino acids, peptides, sugars, inorganic salts, etc. The presence of these ingredients makes tryptophan fermentation broth have a high resource utilization value, especially the amino acid component, which is a nutrient element necessary for plant growth and can be directly absorbed and utilized by plants to provide nitrogen sources and other necessary chemical structural units for plants, which helps to promote plant metabolism and growth. Using tryptophan fermentation broth as a raw material to prepare fertilizer can not only solve the problem of fermentation waste liquid treatment and reduce environmental pollution, but also realize the effective recycling of resources, which is in line with the concept of sustainable development; When extracting amino acids from fermentation waste liquid, traditional treatment methods may cause the structure of amino acids to be destroyed or chemical reactions to lose activity due to violent chemical reactions, high temperature, high pH and other conditions. In certain concentration or separation steps, excessively high temperatures may cause amino acids to undergo deamination, oxidation and other reactions, reducing the effective content of amino acids and the nutritional value of fertilizers. To this end, we propose a method for preparing fertilizers using amino acids from high-purity tryptophan fermentation waste liquid. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing fertilizer by using amino acids in high-purity tryptophan fermentation waste liquid.

[0004] In order to solve the problems raised in the above background technology, the present invention provides the following technical solutions: a method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid, comprising pretreatment of tryptophan fermentation waste liquid, amino acid enrichment, nutrient blending and post-treatment operations, wherein the specific operation steps of preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid are as follows: Step 1, collecting high-purity tryptophan fermentation waste liquid, filtering it through a filtering device, adding a flocculant and precipitating it under ultrasonic treatment, collecting the supernatant and transferring it to a centrifugal device, and obtaining a high-purity tryptophan fermentation liquid after low-temperature centrifugation; Step 2: Use a polymer membrane to separate the high-purity tryptophan fermentation broth, pass it through an ion exchange column after separation, perform ion exchange on the fermentation broth, elute the resin with a buffer solution, and collect the eluate as an amino acid solution; Step 3: adding potassium dihydrogen phosphate, potassium sulfate and a chelate of trace elements to the amino acid solution according to the ratio of the required nutrient elements, and adding a stabilizer thereto after mixing to obtain a fertilizer solution; Step 4: Filter and sterilize the prepared fertilizer solution through a microporous filter membrane. After completion, a liquid fertilizer product is obtained, and the product is subjected to quality and safety tests. After passing the tests, the product is filled into a sealed container and stored at room temperature.

[0005] As a further scheme of the present invention: in the step 1, the high-purity tryptophan fermentation waste liquid is collected into an insulated storage tank, the temperature of the storage tank is maintained between 18°C ​​and 20°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a filtering device with a specific double-layer filter screen, the pore size of the outer filter screen is 80um-100um, and the pore size of the inner filter screen is 20um-30um, and the high-purity tryptophan fermentation waste liquid is passed through the filtering device at a flow rate of 8L / min-10L / min to remove large-particle impurities in the waste liquid, and the fermentation waste liquid filtrate is collected after the filtration is completed.

[0006] As a further scheme of the present invention: in the step one, a new composite flocculant is added to the fermentation waste liquid filtrate, which is composed of natural high molecular weight polysaccharides, biologically active proteins and specific metal ion chelating agents, and the addition amount of the new composite flocculant is 5g-8g per liter of fermentation waste liquid filtrate. The new composite flocculant is added to the fermentation waste liquid filtrate, and the ultrasonic treatment equipment is turned on at the same time, the ultrasonic frequency is set to 30kHz-40kHz, the power is 200W-300W, and the ultrasonic treatment time is 15min-20min. After the treatment is completed, the ultrasonic treatment liquid is collected for standby use.

[0007] As a further scheme of the present invention: in the step 1, the ultrasonic treatment liquid is transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature is set to 2°C-4°C, the speed is 4000r / min-5000r / min, the centrifugation time is 12min-15min, and after the centrifugation is completed, the supernatant is collected as a high-purity tryptophan fermentation broth.

[0008] As a further solution of the present invention: in the step 2, polysulfone and polyethersulfone are selected to be mixed in a ratio of 3:2 to form a membrane, and hydrophilic nano titanium dioxide particles with a mass fraction of 5% are added thereto. Before use, the polymer membrane is soaked in a 0.1 mol / L sodium hydroxide solution for 2h-3h, and after soaking, it is taken out and rinsed with deionized water until the pH value of the rinse solution is between 6.5-7.5, and then the polymer membrane is soaked in a bovine serum albumin solution with a mass fraction of 0.5% for 1h-2h, and high-purity tryptophan fermentation broth is introduced into the polymer membrane, the operating pressure is controlled to be 0.3MPa-0.5MPa, the temperature is 20℃-22℃, and the polymer membrane is used for cross-flow filtration mode, and the cross-flow velocity is 1.5m / s-2.0m / s. For a tryptophan molecule with a molecular weight of 204D, its diffusion and permeation process in the membrane driven by the pressure difference is represented by the following equation: ; in is the solute flux, is the permeability coefficient of the membrane, is the operating pressure difference, is the emission coefficient, The osmotic pressure difference retains the macromolecular impurities in the high-purity tryptophan fermentation broth in front of the membrane.

[0009] As a further solution of the present invention: in the step 2, the ion exchange resin column is a composite ion exchange resin column, which is a mixture of a strongly acidic cation exchange resin and a weakly alkaline anion exchange resin in a volume ratio of 2:1. Before filling, the two ion exchange resin columns are soaked in deionized water for 24h-36h. After the soaking, the cation exchange resin is transformed using a 2mol / L hydrochloric acid solution with a volume of 2-3 times the column volume to change the active group in the cation exchange resin from -SO 3 Na is converted to -SO 3 H, use 2-3 column volumes of 2 mol / L sodium hydroxide solution to transform the anion exchange resin, and change the active groups on the anion exchange resin from -NR 3 Cl is converted to -NR 3OH, mix the two transformed resins evenly and fill them into the ion exchange column. The filling height is 80%-90% of the height of the ion exchange column. After filling, use deionized water to flush the ion exchange resin column at a flow rate of 2BV / h-3BV / h for 4h-6h, and detect the conductivity of the effluent. When the conductivity of the effluent is less than 5uS / cm, start the ion exchange operation.

[0010] As a further scheme of the present invention: in the step 2, the fermentation broth after polymer membrane separation is introduced into the ion exchange resin column at a flow rate of 1 mL / min-2 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 20°C-25°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1 BV / h-2 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system is selected as the buffer with a concentration of 0.2 mol / L-0.3 mol / L. The prepared buffer is slowly injected from the top of the ion exchange resin column at a flow rate of 0.5 mL / min-1.0 mL / min, so that the buffer flows through the ion exchange resin column from top to bottom. During the elution process, the citrate ions and hydrogen ions in the buffer undergo a replacement reaction with the amino acids bound to the resin, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution.

[0011] As a further scheme of the present invention: in the step three, potassium dihydrogen phosphate, potassium sulfate and trace element chelates are added to the amino acid solution, the amount of potassium dihydrogen phosphate added is 6g-8g per liter of amino acid solution, and the mixture is stirred at 200r / min-300r / min after addition. Potassium sulfate is added after stirring for 15min-20min, and the amount of potassium sulfate added is 4g-6g per liter of amino acid solution. After stirring and mixing, trace element chelates are added, and the amount of trace element chelates added is 0.8g-1.2g per liter of amino acid solution. After stirring and mixing, a stabilizer is added, and the amount of the stabilizer added is 0.5%-0.8% of the total mass of the amino acid solution. During the addition process, the stirring speed is controlled to 800r / min-1000r / min, and the mixture is stirred for 30min-40min until the stabilizer is fully dispersed and interacts with the nutrients in the solution to obtain a fertilizer solution.

[0012] As a further scheme of the present invention: in the step 4, a microporous filter membrane made of a blend of polyvinylidene fluoride and polytetrafluoroethylene is selected to filter the fertilizer solution, and the prepared fertilizer solution is introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 5mL / min-8mL / min. During the filtration process, an intermittent filtration method is adopted, and the filtration is suspended for 2min-3min every 10min-15min of filtration. After the filtration is completed, the filtrate is collected as a liquid fertilizer product, and a liquid fertilizer sample is taken for quality inspection, including nutrient component analysis, stability inspection, heavy metal inspection and microbial safety inspection. After passing the inspection, the liquid fertilizer product is filled in a sealed container under a sterile environment, and after filling, it is stored in a dry and ventilated warehouse.

[0013] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. The present invention uses high-purity tryptophan fermentation waste liquid as a raw material to prepare fertilizer, fully utilizes multiple nutrients in the waste liquid, converts waste that may cause environmental pollution into valuable resources, solves the problem of fermentation waste liquid treatment, reduces pollution to the environment, and realizes effective recycling of resources. By using a specially treated polymer membrane to perform cross-flow filtration on the tryptophan fermentation waste liquid under mild conditions, macromolecular impurities can be effectively intercepted to prevent amino acids from being damaged by high temperature, high pressure or chemical action during the separation process. After the composite ion exchange resin column is strictly transformed and flushed, ion exchange and buffer elution are performed at a suitable temperature to ensure the structural integrity of the amino acids during the enrichment process, increase the content of effective amino acids in the fertilizer, and maintain the high nutritional value of the fertilizer. The new composite flocculant combined with ultrasonic treatment can gently remove impurities in the waste liquid filtrate, avoid the damage to the amino acid structure due to violent chemical reactions, and further separate impurities by low-temperature centrifugation to ensure that the activity of amino acids is not damaged during the entire pretreatment process, thereby ensuring the nutritional value of the fertilizer; 2. The present invention adds potassium dihydrogen phosphate, potassium sulfate and trace element chelates in proportion according to plant growth requirements, so that the fertilizer contains comprehensive and balanced nutrients, meets the needs of plants at different growth stages, promotes plant growth and improves crop yield and quality. The addition of a stabilizer can prevent the precipitation and stratification of nutrients in the fertilizer solution, ensure the stability of the fertilizer during storage and use, and ensure that the nutrients are continuously and effectively supplied to plants. The microporous filter membrane made of a blend of polyvinylidene fluoride and polytetrafluoroethylene combined with an intermittent filtration method can effectively remove microorganisms in the fertilizer solution, avoid clogging of the filter membrane, and ensure the filtration and sterilization effect. The quality inspection process covers nutrient analysis, stability testing, heavy metal testing and microbial safety testing, ensuring that the fertilizer is of qualified quality, low in heavy metal content, and free of harmful microorganisms, thereby ensuring the safety of the fertilizer during storage and use and avoiding adverse effects on the soil, plants and the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the process of preparing liquid fertilizer from amino acids in tryptophan fermentation waste liquid in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] The present invention discloses a method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid, comprising pretreatment of the tryptophan fermentation waste liquid, amino acid enrichment, nutrient blending and post-treatment operations. The specific operation steps of preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid are as follows: Step 1, collecting high-purity tryptophan fermentation waste liquid, filtering it through a filtering device, adding a flocculant and precipitating it under ultrasonic treatment, collecting the supernatant and transferring it to a centrifugal device, and obtaining a high-purity tryptophan fermentation liquid after low-temperature centrifugation; Step 2: Use a polymer membrane to separate the high-purity tryptophan fermentation broth, pass it through an ion exchange column after separation, perform ion exchange on the fermentation broth, elute the resin with a buffer solution, and collect the eluate as an amino acid solution; Step 3: adding potassium dihydrogen phosphate, potassium sulfate and a chelate of trace elements to the amino acid solution according to the ratio of the required nutrient elements, and adding a stabilizer thereto after mixing to obtain a fertilizer solution; Step 4: Filter and sterilize the prepared fertilizer solution through a microporous filter membrane. After completion, a liquid fertilizer product is obtained, and the product is subjected to quality and safety tests. After passing the tests, the product is filled into a sealed container and stored at room temperature.

[0017] In one embodiment of the present invention: in step 1, the high-purity tryptophan fermentation waste liquid is collected into an insulated storage tank, the temperature of the storage tank is maintained between 18°C ​​and 20°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a specific double-layer filter device, the pore size of the outer filter is 80um-100um, and the pore size of the inner filter is 20um-30um. The high-purity tryptophan fermentation waste liquid passes through the filtering device at a flow rate of 8L / min-10L / min to remove large-particle impurities in the waste liquid, and the fermentation waste liquid filtrate is collected after the filtration is completed.

[0018] In one embodiment of the present invention: in step one, a new composite flocculant is added to the fermentation waste liquid filtrate, which is composed of natural high molecular weight polysaccharides, biologically active proteins and specific metal ion chelating agents, and the addition amount of the new composite flocculant is 5g-8g per liter of fermentation waste liquid filtrate. The new composite flocculant is added to the fermentation waste liquid filtrate, and the ultrasonic treatment equipment is turned on at the same time, the ultrasonic frequency is set to 30kHz-40kHz, the power is 200W-300W, and the ultrasonic treatment time is 15min-20min. After the treatment is completed, the ultrasonic treatment liquid is collected for use.

[0019] In one embodiment of the present invention: in step 1, the ultrasonically treated liquid is transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature is set to 2°C-4°C, the rotation speed is 4000r / min-5000r / min, the centrifugation time is 12min-15min, and after the centrifugation is completed, the supernatant is collected as a high-purity tryptophan fermentation broth.

[0020] In one embodiment of the present invention: in step 2, polysulfone and polyethersulfone are selected to be mixed in a ratio of 3:2 to form a membrane, and hydrophilic nano titanium dioxide particles with a mass fraction of 5% are added thereto. Before use, the polymer membrane is soaked in a 0.1 mol / L sodium hydroxide solution for 2h-3h, and after soaking, it is taken out and rinsed with deionized water until the pH value of the rinse solution is between 6.5-7.5, and then the polymer membrane is soaked in a bovine serum albumin solution with a mass fraction of 0.5% for 1h-2h, and high-purity tryptophan fermentation broth is introduced into the polymer membrane, the operating pressure is controlled to be 0.3MPa-0.5MPa, the temperature is 20℃-22℃, and the polymer membrane is used for cross-flow filtration mode, and the cross-flow velocity is 1.5m / s-2.0m / s. For a tryptophan molecule with a molecular weight of 204D, its diffusion and permeation process in the membrane driven by the pressure difference is represented by the following equation: ; in is the solute flux, is the permeability coefficient of the membrane, is the operating pressure difference, is the emission coefficient, The osmotic pressure difference retains the macromolecular impurities in the high-purity tryptophan fermentation broth in front of the membrane.

[0021] In one embodiment of the present invention, in step 2, the ion exchange resin column is a composite ion exchange resin column, which is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin in a volume ratio of 2:1. Before filling, the two ion exchange resin columns are soaked in deionized water for 24h-36h. After the soaking, the cation exchange resin is transformed with a 2mol / L hydrochloric acid solution of 2-3 times the column volume to change the active group in the cation exchange resin from -SO 3 Na is converted to -SO 3 H, use 2-3 column volumes of 2 mol / L sodium hydroxide solution to transform the anion exchange resin, and change the active groups on the anion exchange resin from -NR 3 Cl is converted to -NR 3 OH, mix the two transformed resins evenly and fill them into the ion exchange column. The filling height is 80%-90% of the height of the ion exchange column. After filling, use deionized water to flush the ion exchange resin column at a flow rate of 2BV / h-3BV / h for 4h-6h, and detect the conductivity of the effluent. When the conductivity of the effluent is less than 5uS / cm, start the ion exchange operation.

[0022] In one embodiment of the present invention: in step 2, the fermentation broth separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 1 mL / min-2 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 20°C-25°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1 BV / h-2 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system is selected as the buffer with a concentration of 0.2 mol / L-0.3 mol / L. The prepared buffer is slowly injected from the top of the ion exchange resin column at a flow rate of 0.5 mL / min-1.0 mL / min, so that the buffer flows through the ion exchange resin column from top to bottom. During the elution process, the citrate ions and hydrogen ions in the buffer react with the amino acids bound to the resin to undergo a replacement reaction, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution.

[0023] In one embodiment of the present invention: in step three, potassium dihydrogen phosphate, potassium sulfate and trace element chelates are added to the amino acid solution, the amount of potassium dihydrogen phosphate added is 6g-8g per liter of amino acid solution, and the mixture is stirred at 200r / min-300r / min after addition. Potassium sulfate is added after stirring for 15min-20min, and the amount of potassium sulfate added is 4g-6g per liter of amino acid solution. After stirring and mixing, trace element chelates are added, and the amount of trace element chelates added is 0.8g-1.2g per liter of amino acid solution. After stirring and mixing, a stabilizer is added, and the amount of the stabilizer added is 0.5%-0.8% of the total mass of the amino acid solution. During the addition process, the stirring speed is controlled to 800r / min-1000r / min, and the mixture is stirred for 30min-40min until the stabilizer is fully dispersed and interacts with the nutrients in the solution to obtain a fertilizer solution.

[0024] In one embodiment of the present invention: in step 4, a microporous filter membrane made of a blend of polyvinylidene fluoride and polytetrafluoroethylene is used to filter the fertilizer solution, and the prepared fertilizer solution is introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 5mL / min-8mL / min. During the filtration process, an intermittent filtration method is adopted, and the filtration is suspended for 2min-3min every 10min-15min of filtration. After the filtration is completed, the filtrate is collected as a liquid fertilizer product, and a liquid fertilizer sample is taken for quality inspection, including nutrient component analysis, stability inspection, heavy metal inspection and microbial safety inspection. After passing the inspection, the liquid fertilizer product is filled in a sealed container under a sterile environment, and after filling, it is stored in a dry and ventilated warehouse.

[0025] In one embodiment of the present invention: in step 2, according to the characteristic of the membrane's molecular weight cutoff (MWCO) of 1 kDa-2 kDa, small molecular weight amino acids such as tryptophan can pass through the membrane smoothly, while large molecular weight polypeptides, polysaccharides and some protein impurities are retained.

[0026] In one embodiment of the present invention: in step 3, potassium dihydrogen phosphate is added to the amino acid solution, and a high-precision peristaltic pump is used during the addition process. When the potassium dihydrogen phosphate is fully dissolved and evenly distributed in the solution, the potassium dihydrogen phosphate undergoes an ionization reaction in the solution as follows: ; The ionized ions provide phosphorus and potassium for plant growth, and participate in important physiological processes such as plant photosynthesis, energy metabolism, and genetic material synthesis.

[0027] In one embodiment of the present invention: in step 3, potassium sulfate is added to the amino acid solution, and a peristaltic pump is used to add the potassium sulfate, and the potassium sulfate is completely ionized in the solution: ; The ionized ions provide potassium to plants, enhance their stress resistance, and improve their resistance to drought, pests and diseases, etc. At the same time, they help regulate the osmotic pressure of plant cells and maintain the normal morphology and function of cells.

[0028] In one embodiment of the present invention: in step three, the stabilizer is made of a combination of a polysaccharide substance (chitosan) and a new type of high molecular polymer (poly-gamma-glutamic acid). Chitosan is interconnected through intermolecular hydrogen bonds and electrostatic effects to form a three-dimensional network structure. Poly-gamma-glutamic acid can be entangled in the network structure. The addition of the stabilizer can prevent the precipitation and stratification of nutrients in the fertilizer solution, and has a certain slow-release effect, which can prolong the action time of the fertilizer.

[0029] Embodiment 1 The high-purity tryptophan fermentation waste liquid is collected into a heat-insulating storage tank, the temperature of the storage tank is maintained at 18°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a filtering device with a double-layer filter screen, the pore size of the outer filter screen is 80um, and the pore size of the inner filter screen is 20um. The high-purity tryptophan fermentation waste liquid passes through the filtering device at a flow rate of 8L / min, and the fermentation waste liquid filtrate is collected; Add a new composite flocculant (the new composite flocculant is composed of natural high molecular weight polysaccharide, bioactive protein and specific metal ion chelating agent) to the fermentation waste liquid filtrate, the addition amount is 5g per liter of fermentation waste liquid filtrate, and turn on the ultrasonic treatment equipment at the same time, set the ultrasonic frequency to 30kHz, the power to 200W, the ultrasonic treatment time to 15min, and collect the ultrasonic treatment liquid; The ultrasonic treatment liquid was transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature was set to 2°C, the speed was set to 4000r / min, the centrifugation time was set to 12min, and the supernatant was collected as a high-purity tryptophan fermentation liquid; Polysulfone and polyethersulfone were mixed in a ratio of 3:2 to form a membrane, and 5% by mass of hydrophilic nano-titanium dioxide particles were added thereto. Before use, the polymer membrane was immersed in a 0.1 mol / L sodium hydroxide solution for 2 hours. After immersion, the membrane was taken out and rinsed with deionized water until the pH value of the rinse solution was 6.5. The polymer membrane was then immersed in a bovine serum albumin solution containing a mass fraction of 0.5% for 1 hour. High-purity tryptophan fermentation broth was introduced into the polymer membrane. The operating pressure was controlled to be 0.3 MPa and the temperature to be 20°C. The polymer membrane was used for cross-flow filtration mode at a cross-flow velocity of 1.5 m / s. The ion exchange resin column uses a composite ion exchange resin column (strong acid cation exchange resin and weak base anion exchange resin mixed in a volume ratio of 2:1). Before filling, the two ion exchange resin columns are soaked in deionized water for 24 hours. After soaking, the cation exchange resin is transformed with 2 mol / L hydrochloric acid solution with 2 times the column volume to change the active group in the cation exchange resin from -SO 3 Na is converted to -SO 3 H, the anion exchange resin was transformed with 2 mol / L sodium hydroxide solution with 2 column volumes to change the active groups on the anion exchange resin from -NR 3 Cl is converted to -NR 3 OH, the two resins after transformation are mixed evenly and filled into the ion exchange column, the filling height is 80% of the height of the ion exchange column, after the filling is completed, the ion exchange resin column is flushed with deionized water at a flow rate of 2BV / h for 4h, the conductivity of the effluent is detected, and the ion exchange operation is started when the conductivity of the effluent is less than 5uS / cm; The fermentation liquid separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 1 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 20°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system with a concentration of 0.2 mol / L is selected as a buffer solution, and the prepared buffer solution is slowly injected from the top of the ion exchange resin column at a flow rate of 0.5 mL / min, so that the buffer solution flows through the ion exchange resin column from top to bottom, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution; Potassium dihydrogen phosphate (6 g per liter of amino acid solution) was added to the amino acid solution, and stirred at 200 r / min after adding. Potassium sulfate (4 g per liter of amino acid solution) was added after stirring for 15 minutes. Trace element chelate (0.8 g per liter of amino acid solution) was added after stirring and mixing. A stabilizer (the amount of stabilizer added was 0.5% of the total mass of the amino acid solution) was added after stirring and mixing. During the adding process, the stirring speed was controlled to 800 r / min. The solution was stirred for 30 minutes until the stabilizer was fully dispersed and interacted with the nutrients in the solution to obtain a fertilizer solution. A microporous filter membrane made of a blend of polyvinylidene fluoride and polytetrafluoroethylene was used to filter the fertilizer solution. The prepared fertilizer solution was introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 5 mL / min. During the filtration process, intermittent filtration was adopted. After filtering for 10 minutes, the filtration was suspended for 2 minutes. After the filtration was completed, the filtrate was collected as a liquid fertilizer product.

[0030] Embodiment 2 The high-purity tryptophan fermentation waste liquid is collected into an insulated storage tank, the temperature of the storage tank is maintained at 19°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a double-layer filter device, the pore size of the outer filter is 90um, and the pore size of the inner filter is 25um. The high-purity tryptophan fermentation waste liquid passes through the filter device at a flow rate of 9L / min, and the fermentation waste liquid filtrate is collected; Add the new composite flocculant to the fermentation waste liquid filtrate, the addition amount is 6.5g per liter of fermentation waste liquid filtrate, turn on the ultrasonic treatment equipment at the same time, set the ultrasonic frequency to 35kHz, the power to 250W, the ultrasonic treatment time to 18min, and collect the ultrasonic treatment liquid; The ultrasonic treatment liquid was transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature was set to 3°C, the speed was set to 4500r / min, the centrifugation time was set to 13min, and the supernatant was collected as a high-purity tryptophan fermentation liquid; Polysulfone and polyethersulfone were mixed in a ratio of 3:2 to form a membrane, and 5% by mass of hydrophilic nano-titanium dioxide particles were added thereto. Before use, the polymer membrane was soaked in a 0.1 mol / L sodium hydroxide solution for 2.5 hours. After soaking, the membrane was taken out and rinsed with deionized water until the pH value of the rinse solution was 7. The polymer membrane was then soaked in a bovine serum albumin solution containing 0.5% by mass for 1.5 hours. High-purity tryptophan fermentation broth was introduced into the polymer membrane. The operating pressure was controlled to be 0.4 MPa and the temperature to be 21°C. The polymer membrane was used for cross-flow filtration mode at a cross-flow velocity of 1.8 m / s. The ion exchange resin column uses a composite ion exchange resin column. Before filling, soak the two ion exchange resin columns in deionized water for 30 hours. After soaking, use 2.5 times the column volume of 2mol / L hydrochloric acid solution to transform the cation exchange resin, and use 2.5 times the column volume of 2mol / L sodium hydroxide solution to transform the anion exchange resin. Mix the two transformed resins evenly and fill them into the ion exchange column. The filling height is 85% of the height of the ion exchange column. After filling, use deionized water to rinse the ion exchange resin column at a flow rate of 2.5BV / h for 5 hours, detect the conductivity of the effluent, and start the ion exchange operation when the conductivity of the effluent is less than 5uS / cm; The fermentation liquid separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 1.5 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 23°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1.5 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system with a concentration of 0.25 mol / L is selected as a buffer solution, and the prepared buffer solution is slowly injected from the top of the ion exchange resin column at a flow rate of 0.8 mL / min, so that the buffer solution flows through the ion exchange resin column from top to bottom, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution; Potassium dihydrogen phosphate (7 g per liter of amino acid solution) was added to the amino acid solution, and the mixture was stirred at 250 r / min. Potassium sulfate (5 g per liter of amino acid solution) was added after stirring for 18 minutes. Trace element chelate (1 g per liter of amino acid solution) was added after stirring and mixing. A stabilizer (the amount of stabilizer added was 0.65% of the total mass of the amino acid solution) was added after stirring and mixing. During the addition process, the stirring speed was controlled to 900 r / min. The mixture was stirred for 35 minutes until the stabilizer was fully dispersed and interacted with the nutrients in the solution to obtain a fertilizer solution. A microporous filter membrane was used to filter the fertilizer solution. The prepared fertilizer solution was introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 6.5 mL / min. During the filtration process, the filtration was suspended for 2.5 minutes every 13 minutes. After the filtration was completed, the filtrate was collected as a liquid fertilizer product.

[0031] Embodiment 3 The high-purity tryptophan fermentation waste liquid is collected into a heat-insulating storage tank, the temperature of the storage tank is maintained at 20°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a filtering device with a double-layer filter screen, the pore size of the outer filter screen is 100um, and the pore size of the inner filter screen is 30um. The high-purity tryptophan fermentation waste liquid passes through the filtering device at a flow rate of 10L / min, and the fermentation waste liquid filtrate is collected; Add the new composite flocculant to the fermentation waste liquid filtrate, the addition amount is 8g per liter of fermentation waste liquid filtrate, turn on the ultrasonic treatment equipment at the same time, set the ultrasonic frequency to 40kHz, the power to 300W, the ultrasonic treatment time to 20min, and collect the ultrasonic treatment liquid; The ultrasonic treatment liquid was transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature was set to 4°C, the speed was set to 5000r / min, the centrifugation time was set to 15min, and the supernatant was collected as a high-purity tryptophan fermentation liquid; Polysulfone and polyethersulfone were mixed in a ratio of 3:2 to form a membrane, and hydrophilic nano-titanium dioxide particles with a mass fraction of 5% were added thereto. Before use, the polymer membrane was immersed in a 0.1 mol / L sodium hydroxide solution for 3 hours. After immersion, the membrane was taken out and rinsed with deionized water until the pH value of the rinse solution was 7.5. The polymer membrane was then immersed in a bovine serum albumin solution with a mass fraction of 0.5% for 2 hours. High-purity tryptophan fermentation broth was introduced into the polymer membrane. The operating pressure was controlled to be 0.5 MPa and the temperature to be 22°C. The polymer membrane was used for cross-flow filtration mode with a cross-flow velocity of 2.0 m / s. The ion exchange resin column uses a composite ion exchange resin column. Before filling, soak the two ion exchange resin columns in deionized water for 36 hours. After soaking, use 3 times the column volume of 2mol / L hydrochloric acid solution to transform the cation exchange resin, and use 3 times the column volume of 2mol / L sodium hydroxide solution to transform the anion exchange resin. Mix the two transformed resins evenly and fill them into the ion exchange column. The filling height is 90% of the height of the ion exchange column. After filling, use deionized water to rinse the ion exchange resin column at a flow rate of 3BV / h for 6 hours, detect the conductivity of the effluent, and start the ion exchange operation when the conductivity of the effluent is less than 5uS / cm; The fermentation liquid separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 2 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 25°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 2 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system with a concentration of 0.3 mol / L is selected as a buffer solution, and the prepared buffer solution is slowly injected from the top of the ion exchange resin column at a flow rate of 1.0 mL / min, so that the buffer solution flows through the ion exchange resin column from top to bottom, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution; Add potassium dihydrogen phosphate (8 g per liter of amino acid solution) to the amino acid solution, stir at 300 r / min after adding, add potassium sulfate (6 g per liter of amino acid solution) after stirring for 20 minutes, add trace element chelate (1.2 g per liter of amino acid solution) after stirring and mixing, add stabilizer after stirring and mixing (the amount of stabilizer added is 0.8% of the total mass of the amino acid solution), during the adding process, control the stirring speed to 1000 r / min, stir for 40 minutes until the stabilizer is fully dispersed and interacts with the nutrients in the solution, and prepare a fertilizer solution; A microporous filter membrane is used to filter the fertilizer solution. The prepared fertilizer solution is introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 8 mL / min. During the filtration process, the filtration is suspended for 3 minutes every 15 minutes. After the filtration is completed, the filtrate is collected as a finished liquid fertilizer.

[0032] Embodiment 4: The high-purity tryptophan fermentation waste liquid is collected into a heat-insulating storage tank, the temperature of the storage tank is maintained at 18.5°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a double-layer filter device, the pore size of the outer filter is 85um, and the pore size of the inner filter is 22um. The high-purity tryptophan fermentation waste liquid passes through the filter device at a flow rate of 8.5L / min, and the fermentation waste liquid filtrate is collected; Add the new composite flocculant to the fermentation waste liquid filtrate, the addition amount is 6g per liter of fermentation waste liquid filtrate, turn on the ultrasonic treatment equipment at the same time, set the ultrasonic frequency to 32kHz, the power to 220W, the ultrasonic treatment time to 16min, and collect the ultrasonic treatment liquid; The ultrasonic treatment liquid was transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature was set to 2.5°C, the speed was set to 4200r / min, the centrifugation time was set to 13min, and the supernatant was collected as a high-purity tryptophan fermentation liquid; Polysulfone and polyethersulfone were mixed in a ratio of 3:2 to form a membrane, and hydrophilic nano-titanium dioxide particles with a mass fraction of 5% were added thereto. Before use, the polymer membrane was soaked in a 0.1 mol / L sodium hydroxide solution for 2.2 hours. After soaking, the membrane was taken out and rinsed with deionized water until the pH value of the rinse solution was 6.8. The polymer membrane was then soaked in a bovine serum albumin solution with a mass fraction of 0.5% for 1.2 hours. High-purity tryptophan fermentation broth was introduced into the polymer membrane. The operating pressure was controlled to be 0.35 MPa and the temperature to be 20.5°C. The polymer membrane was used for cross-flow filtration mode with a cross-flow velocity of 1.6 m / s. The ion exchange resin column uses a composite ion exchange resin column. Before filling, soak the two ion exchange resin columns in deionized water for 26 hours. After soaking, use 2.2 times the column volume of 2mol / L hydrochloric acid solution to transform the cation exchange resin, and use 2.2 times the column volume of 2mol / L sodium hydroxide solution to transform the anion exchange resin. Mix the two transformed resins evenly and fill them into the ion exchange column. The filling height is 82% of the height of the ion exchange column. After filling, use deionized water to rinse the ion exchange resin column at a flow rate of 2.2BV / h for 4.5 hours, detect the conductivity of the effluent, and start the ion exchange operation when the conductivity of the effluent is less than 5uS / cm; The fermentation liquid separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 1.2 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 21°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1.2 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system with a concentration of 0.22 mol / L is selected as a buffer. The prepared buffer is slowly injected from the top of the ion exchange resin column at a flow rate of 0.6 mL / min, so that the buffer flows through the ion exchange resin column from top to bottom, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution; Potassium dihydrogen phosphate (6.5 g per liter of amino acid solution) was added to the amino acid solution, and the mixture was stirred at 220 r / min. Potassium sulfate (4.5 g per liter of amino acid solution) was added after stirring for 16 minutes. Trace element chelate (0.9 g per liter of amino acid solution) was added after stirring and mixing. A stabilizer (the amount of stabilizer added was 0.6% of the total mass of the amino acid solution) was added after stirring and mixing. During the addition process, the stirring speed was controlled to 850 r / min. The mixture was stirred for 32 minutes until the stabilizer was fully dispersed and interacted with the nutrients in the solution to obtain a fertilizer solution. A microporous filter membrane was used to filter the fertilizer solution. The prepared fertilizer solution was introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 6 mL / min. During the filtration process, intermittent filtration was adopted. After filtering for 12 minutes, the filtration was suspended for 2.2 minutes. After the filtration was completed, the filtrate was collected as a liquid fertilizer product.

[0033] The liquid fertilizer products prepared in the above four groups of embodiments were subjected to quality inspection, and the specific inspection methods and inspection data are as follows: Nutritional analysis, Amino acid content detection: High performance liquid chromatography (HPLC) was used, using a C18 reverse phase column, with a specific buffer as the mobile phase, the flow rate was set at 1.0mL / min-1.5mL / min, and the column temperature was maintained at 30-40°C. The fertilizer sample was diluted to a suitable concentration and then injected into the chromatograph. The content of various amino acids was quantitatively analyzed by comparing the retention time and peak area with those of the standard amino acid sample; Trace element detection: Using inductively coupled plasma optical emission spectrometry (ICP-OES), the fertilizer sample is digested to make a solution, which is then introduced into the ICP-OES instrument. Quantitative analysis is performed based on the characteristic emission spectra of different trace elements. The content of trace elements such as iron, zinc, manganese, copper, boron, and molybdenum can be detected simultaneously.

[0034] Stability testing, Thermal stability test: Place the fertilizer samples in a thermostat at 40°C, 50°C and 60°C for 24-48 hours, and observe whether there is precipitation, stratification, discoloration, etc. on the appearance of the samples. Then, perform nutrient analysis again to detect the loss of nutrients. Long-term stability test: Seal and store the fertilizer samples at room temperature for 3-6 months, and check the sample status regularly every month, including color, transparency, presence of precipitation or odor, etc. At the same time, conduct a comprehensive nutrient analysis and physical property test after the storage period to evaluate the stability of the fertilizer.

[0035] Heavy metal detection, Using atomic absorption spectrometry (AAS) or inductively coupled plasma mass spectrometry (ICP-MS), the fertilizer sample is digested into a solution and then introduced into the corresponding instrument. For AAS, quantitative analysis is performed based on the characteristic absorption wavelengths of different heavy metal elements. For ICP-MS, the mass-to-charge ratio of heavy metal ions is detected using the principle of mass spectrometry to determine their content, with a focus on detecting toxic and harmful heavy metal elements such as lead (Pb), cadmium (Cd), mercury (Hg), chromium (Cr), and arsenic (As).

[0036] Microbiological safety testing, Total bacterial count test: Use the plate count method to dilute the fertilizer sample in a gradient manner, then apply a certain amount of dilution onto a nutrient agar plate, incubate at 37°C for 24-48 hours, count the number of colonies growing on the plate, and calculate the total number of bacteria per milliliter of sample; Detection of total number of molds and yeasts: Dilute the sample and spread it on a red Bengal medium plate, culture it at 28°C for 3-5 days, and count the mold and yeast colonies that grow; Pathogen detection: Use selective culture medium to detect the presence of harmful pathogens such as Escherichia coli and Salmonella, use eosin-methylene blue culture medium to detect Escherichia coli, and observe characteristic colonies after culturing under specific conditions.

[0037] The test results are as follows: Example

[0038] Amino acid content: total amino acid content is 20%, tryptophan content is 3%, and other main amino acids content is 1%-3%; Trace elements: Iron 50mg / L, zinc 30mg / L, manganese 20mg / L, copper 10mg / L, boron 15mg / L and molybdenum 2mg / L.

[0039] Thermal stability (40℃, 50℃, 60℃, 24h): no abnormality, nutrient loss rate: amino acid 3%, phosphorus 2%, potassium 2% and total trace elements 4%; Long-term stability (normal temperature, 6 months): no abnormal nutrient loss rate of amino acids 5%, phosphorus 3%, potassium 3% and total trace elements 6%; Heavy metal detection: None.

[0040] Microbiological safety testing, Total bacteria count: 60CFU / mL; Total mold and yeast count: 30 CFU / mL; Pathogens such as Escherichia coli and Salmonella: Not detected.

[0041] Embodiment 2 Amino acid content: total amino acid content is 22%, tryptophan content is 3.2%, and other main amino acids content is 1.2%-3.5%; Trace elements: Iron 60mg / L, zinc 35mg / L, manganese 22mg / L, copper 12mg / L, boron 18mg / L and molybdenum 3mg / L.

[0042] Thermal stability (40℃, 50℃, 60℃, 24h): no abnormality, nutrient loss rate is 2.5% amino acid, 1.8% phosphorus, 1.5% potassium and 3% total trace elements; Long-term stability (normal temperature, 6 months): no abnormal nutrient loss rate of amino acids 4%, phosphorus 2.5%, potassium 2% and total trace elements 5%; Heavy metal detection: None.

[0043] Microbiological safety testing, Total bacterial count: 50CFU / mL; Total mold and yeast count: 25 CFU / mL; Pathogens such as Escherichia coli and Salmonella: Not detected.

[0044] Embodiment 3 Amino acid content: total amino acid content is 25%, tryptophan content is 3.8%, and other main amino acids content is 1.5%-4%; Trace elements: Iron 70mg / L, zinc 40mg / L, manganese 25mg / L, copper 15mg / L, boron 20mg / L and molybdenum 4mg / L.

[0045] Thermal stability (40℃, 50℃, 60℃, 24h): no abnormality, nutrient loss rate: amino acid 2%, phosphorus 1.5%, potassium 1% and total trace elements 2.5%; Long-term stability (normal temperature, 6 months): no abnormal nutrient loss rate of amino acids 3%, phosphorus 2%, potassium 1.5% and total trace elements 4%; Heavy metal detection: None.

[0046] Microbiological safety testing, Total bacterial count: 40CFU / mL; Total mold and yeast count: 20 CFU / mL; Pathogens such as Escherichia coli and Salmonella: Not detected.

[0047] Embodiment 4: Amino acid content: total amino acid content is 21%, tryptophan content is 3.1%, and other main amino acids content is 1.1%-3.2%; Trace elements: Iron 55mg / L, zinc 32mg / L, manganese 21mg / L, copper 11mg / L, boron 16mg / L and molybdenum 2.5mg / L.

[0048] Thermal stability (40℃, 50℃, 60℃, 24h): no abnormality, nutrient loss rate of amino acids 2.8%, phosphorus 2.2%, potassium 2% and total trace elements 3.5%; Long-term stability (normal temperature, 6 months): no abnormal nutrient loss rate of amino acids 4.5%, phosphorus 3%, potassium 2.5% and trace elements total 5.5%; Heavy metal detection: None.

[0049] Microbiological safety testing, Total bacteria count: 60CFU / mL; Total mold and yeast count: 30 CFU / mL; Pathogens such as Escherichia coli and Salmonella: Not detected.

[0050] In summary, the feasibility and effectiveness of the four groups of embodiments of the present invention in preparing fertilizers with amino acids in high-purity tryptophan fermentation waste liquid have important practical significance and application value.

[0051] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

[0052] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0053] The above contents are merely examples and explanations of the present invention. Various modifications or additions to the specific embodiments described or replacements in similar ways by technicians in the technical field shall fall within the protection scope of the present invention as long as they do not deviate from the invention or exceed the scope defined by the claims.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid, comprising pretreatment of tryptophan fermentation waste liquid, amino acid enrichment, nutrient blending and post-treatment operations, characterized in that: The specific operation steps of preparing fertilizer with amino acids in high-purity tryptophan fermentation waste liquid are as follows: Step 1, collecting high-purity tryptophan fermentation waste liquid, filtering it through a filtering device, adding a flocculant and precipitating it under ultrasonic treatment, taking the supernatant and centrifuging it at low temperature to obtain a high-purity tryptophan fermentation liquid; Step 2: Use a polymer membrane to separate the high-purity tryptophan fermentation broth, pass it through an ion exchange column after separation, perform ion exchange on the fermentation broth, elute the resin with a buffer solution, and collect the eluate as an amino acid solution; Step 3: adding potassium dihydrogen phosphate, potassium sulfate and a chelate of trace elements to the amino acid solution according to the ratio of the required nutrient elements, and adding a stabilizer thereto after mixing to obtain a fertilizer solution; Step 4: Filter and sterilize the prepared fertilizer solution through a microporous filter membrane. After completion, a liquid fertilizer product is obtained, and the product is subjected to quality and safety tests. After passing the tests, the product is filled into a sealed container and stored at room temperature.

2. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 1, the high-purity tryptophan fermentation waste liquid is collected into an insulated storage tank, the temperature of the storage tank is maintained between 18°C ​​and 20°C, and the collected high-purity tryptophan fermentation waste liquid is filtered using a filtering device with a specific double-layer filter screen, the pore size of the outer filter screen is 80um-100um, and the pore size of the inner filter screen is 20um-30um. The high-purity tryptophan fermentation waste liquid passes through the filtering device at a flow rate of 8L / min-10L / min to remove large-particle impurities in the waste liquid, and the fermentation waste liquid filtrate is collected after the filtration is completed.

3. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 1, a new composite flocculant is added to the fermentation waste liquid filtrate, wherein the new composite flocculant is composed of natural high molecular weight polysaccharides, bioactive proteins and specific metal ion chelating agents, and the addition amount of the new composite flocculant is 5g-8g per liter of the fermentation waste liquid filtrate. The new composite flocculant is added to the fermentation waste liquid filtrate, and the ultrasonic treatment equipment is turned on at the same time, and the ultrasonic frequency is set to 30kHz-40kHz, the power is set to 200W-300W, and the ultrasonic treatment time is set to 15min-20min. After the treatment is completed, the ultrasonic treatment liquid is collected for standby use.

4. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 1, the ultrasonic treatment liquid is transferred to a low-temperature centrifuge with precise temperature control, the centrifuge temperature is set to 2°C-4°C, the speed is set to 4000r / min-5000r / min, and the centrifugation time is set to 12min-15min. After the centrifugation is completed, the supernatant is collected as a high-purity tryptophan fermentation liquid.

5. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 2, polysulfone and polyethersulfone are selected to be mixed in a ratio of 3:2 to form a membrane, and hydrophilic nano titanium dioxide particles with a mass fraction of 5% are added thereto. Before use, the polymer membrane is soaked in a 0.1 mol / L sodium hydroxide solution for 2h-3h, and after soaking, it is taken out and rinsed with deionized water until the pH value of the rinse solution is between 6.5-7.5, and then the polymer membrane is soaked in a bovine serum albumin solution with a mass fraction of 0.5% for 1h-2h, and high-purity tryptophan fermentation broth is introduced into the polymer membrane, the operating pressure is controlled to be 0.3MPa-0.5MPa, the temperature is 20℃-22℃, and the polymer membrane is used for cross-flow filtration mode, and the cross-flow velocity is 1.5m / s-2.0m / s. For a tryptophan molecule with a molecular weight of 204D, its diffusion and permeation process in the membrane driven by the pressure difference is represented by the following equation: ; in is the solute flux, is the permeability coefficient of the membrane, is the operating pressure difference, is the emission coefficient, The osmotic pressure difference retains the macromolecular impurities in the high-purity tryptophan fermentation broth in front of the membrane.

6. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 2, the ion exchange resin column uses a composite ion exchange resin column, which is a mixture of a strongly acidic cation exchange resin and a weakly alkaline anion exchange resin in a volume ratio of 2:

1. Before filling, the two ion exchange resin columns are soaked in deionized water for 24h-36h. After the soaking, 2-3 times the column volume of 2mol / L hydrochloric acid solution is used to transform the cation exchange resin to transform the active group in the cation exchange resin from -SO3Na to -SO3H, and 2-3 times the column volume of 2mol / L hydrochloric acid solution is used to transform the active group in the cation exchange resin from -SO3Na to -SO3H. / L of sodium hydroxide solution is used to transform the anion exchange resin, and the active group on the anion exchange resin is transformed from -NR3Cl to -NR3OH. The two transformed resins are mixed evenly and filled into the ion exchange column. The filling height is 80%-90% of the height of the ion exchange column. After the filling is completed, the ion exchange resin column is flushed with deionized water at a flow rate of 2BV / h-3BV / h for 4h-6h, and the conductivity of the effluent is detected. When the conductivity of the effluent is less than 5uS / cm, the ion exchange operation is started.

7. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 2, the fermentation liquid separated by the polymer membrane is introduced into the ion exchange resin column at a flow rate of 1 mL / min-2 mL / min. During the ion exchange process, the temperature of the ion exchange resin column is controlled to be 20°C-25°C. When the ion exchange reaches saturation, the feeding is stopped, and the ion exchange resin column is rinsed with deionized water at a flow rate of 1 BV / h-2 BV / h until the difference between the conductivity of the effluent and the conductivity of the deionized water is less than 0.5 uS / cm. A citric acid-sodium citrate buffer system is selected as the buffer with a concentration of 0.2 mol / L-0.3 mol / L. The prepared buffer is slowly injected from the top of the ion exchange resin column at a flow rate of 0.5 mL / min-1.0 mL / min, so that the buffer flows through the ion exchange resin column from top to bottom. During the elution process, the citrate ions and hydrogen ions in the buffer react with the amino acids bound to the resin, and the eluate flowing out from the bottom of the ion exchange resin column is collected to obtain an amino acid solution.

8. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step three, potassium dihydrogen phosphate, potassium sulfate and trace element chelates are added to the amino acid solution, the amount of potassium dihydrogen phosphate added is 6g-8g per liter of amino acid solution, and the mixture is stirred at 200r / min-300r / min after addition. Potassium sulfate is added after stirring for 15min-20min, and the amount of potassium sulfate added is 4g-6g per liter of amino acid solution. After stirring and mixing, trace element chelates are added, and the amount of trace element chelates added is 0.8g-1.2g per liter of amino acid solution. After stirring and mixing, a stabilizer is added, and the amount of the stabilizer added is 0.5%-0.8% of the total mass of the amino acid solution. During the addition process, the stirring speed is controlled to 800r / min-1000r / min, and the mixture is stirred for 30min-40min until the stabilizer is fully dispersed and interacts with the nutrients in the solution to obtain a fertilizer solution.

9. The method for preparing fertilizer from amino acids in high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 4, a microporous filter membrane made of a blend of polyvinylidene fluoride and polytetrafluoroethylene is used to filter the fertilizer solution, and the prepared fertilizer solution is introduced into a filtration device equipped with a microporous filter membrane through a peristaltic pump at a flow rate of 5 mL / min-8 mL / min. During the filtration process, an intermittent filtration method is adopted, and the filtration is suspended for 2 min-3 min every 10 min-15 min of filtration. After the filtration is completed, the filtrate is collected as a liquid fertilizer product, and a liquid fertilizer sample is taken for quality inspection, including nutrient component analysis, stability inspection, heavy metal inspection and microbial safety inspection. After passing the inspection, the liquid fertilizer product is filled in a sealed container under a sterile environment, and after filling, it is stored in a dry and ventilated warehouse.

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