Process for preparing liquid fertilizer from high-purity tryptophan fermentation waste liquid

Abstract

The invention discloses a process for preparing a liquid fertilizer from high-purity tryptophan fermentation waste liquid, and relates to the technical field of fertilizer preparation, and the process comprises the steps of pretreatment of tryptophan fermentation liquid, concentration of the fermentation waste liquid, component optimization and stabilization treatment. The first filtering operation can remove suspended particles and macromolecular impurities in the waste liquid, the second filtering operation can remove macromolecular substances such as protein aggregates and polysaccharides in the waste liquid, meanwhile, the light transmittance of the waste liquid is improved, and the recovery rate of tryptophan is improved. A low-frequency pulse electromagnetic field is applied into the fermentation tank, so that the permeability of microbial cell membranes can be enhanced, the uptake of microorganisms to substrates and the secretion of metabolites can be promoted, the fermentation efficiency can be improved, and the fermentation time of tryptophan fermentation liquor can be shortened.

Description

Technical Field

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

[0002] In the context of the continuous development of agriculture and industry, fertilizer plays a vital role in improving the yield and quality of crops. At the same time, with the progress of the biotechnology industry, the scale of the fermentation industry is expanding, and the tryptophan fermentation process produces a large amount of fermentation waste liquid; Tryptophan is an important essential amino acid, which is crucial for the synthesis of proteins in organisms. During plant growth, tryptophan participates in the synthesis of the plant hormone indoleacetic acid (IAA), which is a key hormone that can regulate plant growth, development and physiological processes. It can promote the growth and development of plant roots, enhance the adaptability of plants to the environment, and affect the flowering and fruiting of plants. For animals and humans, tryptophan is also a nutrient that cannot be synthesized by themselves but is essential. It plays an important role in physiological processes such as nerve regulation and immune function, and ultimately affects human health through the food chain. In the process of treating tryptophan fermentation waste liquid, due to improper treatment methods, tryptophan and some other valuable nutrients are often lost. Some traditional separation or concentration technologies may destroy the structure of tryptophan due to factors such as high temperature and chemical action, or decompose or inactivate some nutrients that are sensitive to temperature and chemical environment, reducing the nutritional value of the fertilizer. Some evaporation and concentration steps may need to be carried out under high temperature and high pressure, which not only consumes a lot of energy, but also has high maintenance and operation costs for the equipment, resulting in high costs for the entire fertilizer preparation, limiting its large-scale application. In the process of treating tryptophan fermentation liquid, some chemical treatment methods may produce a large amount of wastewater, waste gas or waste residue. If not handled properly, it will pollute the surrounding environment, violating the original intention of resource recycling and environmental protection. To this end, we propose a process for preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid. Summary of the invention

[0003] The object of the present invention is to provide a process for preparing liquid fertilizer by utilizing 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 process for preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid, comprising pretreatment of tryptophan fermentation liquid, concentration of fermentation waste liquid, component optimization and stabilization treatment, wherein the specific operation steps of preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid are as follows: Step 1: collecting high-purity tryptophan fermentation waste liquid, filtering it using two sets of filter membranes, adjusting the pH value of the tryptophan fermentation waste liquid after filtration, adding a flocculant for precipitation, and taking the supernatant as the tryptophan fermentation waste liquid treatment liquid; Step 2: Treating the tryptophan fermentation waste liquid through a nanofiltration membrane, soaking the nanofiltration membrane before treatment, adding the treated waste liquid and the antioxidant mixture into a reactor and stirring after the treatment, and obtaining a tryptophan fermentation liquid after stirring; Step 3: Select a mixed microbial flora, inoculate and ferment the tryptophan fermentation liquid, add an enzyme preparation to the tryptophan fermentation liquid for enzymolysis after the fermentation is completed, and apply a low-frequency pulsed electromagnetic field for treatment, so as to obtain a tryptophan fermentation treatment liquid; Step 4: passing the tryptophan fermentation treatment liquid into an ion exchange resin column, collecting the ion exchange liquid and adding trace elements thereto to obtain a mixed solution; Step 5: Add the natural thickener to the mixed solution and continue stirring until the natural thickener is completely dispersed in the mixed solution to obtain a liquid fertilizer product. Take the liquid fertilizer product for quality monitoring. After passing the monitoring, fill it in a sterile environment.

[0005] As a further scheme of the present invention: in the step 1, the temperature of the waste liquid is maintained at 20°C-22°C during the collection of high-purity tryptophan fermentation waste liquid. After the collection is completed, it is filtered using a graphene-ceramic composite microfiltration membrane with a pore size of 0.02um-0.03um. During the filtration process, the pressure is maintained at 0.12MPa-0.15MPa, the temperature is maintained at 20°C-25°C, and the filtration rate is controlled at 50L / h-60L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1kDa-2kDa, the pressure is controlled to 0.2MPa-0.25MPa, and the filtration is performed at a temperature of 22°C-25°C at a filtration rate of 30L / h-40L / h. After the filtration is completed, a composite pH regulator composed of a biological buffer and an organic acid is added to the filtrate to control the pH value of the tryptophan fermentation waste liquid between 4.0-4.2.

[0006] As a further scheme of the present invention: in the step 1, an inorganic composite flocculant is added to the tryptophan fermentation waste liquid, the inorganic composite flocculant is composed of extracellular polymers produced by microbial metabolism and nano-scale ferric hydroxide in a mass ratio of 3:2, and the amount of the flocculant added is 0.4%-0.6% of the total volume of the tryptophan fermentation waste liquid. After adding the flocculant, stirring at a stirring rate of 40r / min-50r / min for 20min-25min, the flocculant and the tryptophan fermentation waste liquid are fully mixed, and the mixture is allowed to stand for 80min-100min, and the supernatant after precipitation is taken to obtain a tryptophan fermentation waste liquid treated liquid.

[0007] As a further scheme of the present invention: in the step 2, a nanofiltration membrane made of a multilayer nanostructured material is selected, and it is immersed in a buffer solution containing specific electrolytes for 2h-3h before use. After completion, the tryptophan fermentation waste liquid treatment liquid is passed through the nanofiltration membrane at a flow rate of 8L / h-10L / h, and the operating pressure is controlled to be 0.32Mpa-0.38MPa, and the temperature is 25℃-28℃. During the nanofiltration process, an ultrasonic generator is installed on the outside of the nanofiltration membrane, and continuously acts on the surface of the nanofiltration membrane at a frequency of 20kHz-30kHz during the nanofiltration process.

[0008] As a further scheme of the present invention: in the step 2, after the nanofiltration is completed, an antioxidant mixture is added to the solution after nanofiltration, the antioxidant mixture is prepared by a composite of bio-source antioxidant peptides, plant-source flavonoid compounds and nanozymes, and the amount of the antioxidant mixture added is 0.35%-0.45% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 5L / h-8L / h, and the flow rate of the antioxidant mixture is 0.02L / h-0.03L / h. After the antioxidant mixture is uniformly dispersed in the solution after nanofiltration, the mixed solution is stirred at a temperature of 40°C-50°C and a speed of 800r / min-1000r / min for 8min-12min to obtain tryptophan fermentation broth.

[0009] As a further scheme of the present invention: in the step three, the mixed microbial flora is prepared by mixing thermophilic Bacillus, Bacillus amyloliquefaciens, Lactobacillus plantarum and Rhodococcus in a quantitative ratio of 2:3:3:2, and the mixed microbial flora is inoculated into the tryptophan fermentation broth in a fermenter, and the inoculation amount is 6%-8% of the total volume of the tryptophan fermentation broth. The temperature is controlled between 32°C and 35°C during fermentation, and the pH value of the tryptophan fermentation broth is monitored in real time during fermentation. The dripping speed of the buffer solution is adjusted according to the pH value, and the fermentation process lasts for 36h-48h. During the fermentation process, a low-frequency pulsed electromagnetic field is applied to the fermenter every 2h-3h, and the electromagnetic intensity is 0.5mT-1mT, the frequency is 5Hz-10Hz, and the duration of a single application of the low-frequency pulsed magnetic field is 10min-15min.

[0010] As a further scheme of the present invention: in the step three, after the fermentation is completed, a composite enzyme preparation is added thereto, wherein the composite enzyme preparation is prepared by mixing glycoside hydrolase, multifunctional oxidase and aminopeptidase in a mass ratio of 3:2:1, and the total addition amount of the composite enzyme preparation is 0.5%-0.7% of the mass of the fermentation liquid. During the enzymatic hydrolysis process, the temperature is controlled at 35°C-40°C, and the enzymatic hydrolysis reaction lasts for 12h-16h. After completion, a tryptophan fermentation treatment liquid is obtained.

[0011] As a further scheme of the present invention: in the step 4, a new ion exchange resin column is selected, the internal resin of which is formed by grafting a polystyrene-divinylbenzene body with a special functional group, the functional groups include carboxymethyl, aminophosphoric acid and thiol, and the ratio of the functional groups is 3:2:1, the tryptophan fermentation treatment liquid is passed into the ion exchange resin column at a low flow rate of 2L / h-3L / h, the operating temperature is controlled at 28°C-30°C, and an ion exchange liquid is obtained after passing through the ion exchange resin column, and trace elements are added thereto, including chelated zinc, boron, manganese, iron and molybdenum, and zinc, boron, manganese, iron and molybdenum are added in the form of sodium zinc ethylenediaminetetraacetate, sodium octaborate tetrahydrate, manganese glycine, sodium iron ethylenediaminetetraacetate and ammonium molybdate, and the added amounts are 2mg / L-3mg / L, 1mg / L-2mg / L, 0.5mg / L-1mg / L, 1mg / L-2mg / L and 0.1mg / L-0.2mg / L, respectively, and a mixed solution is obtained after adding the trace elements and mixing.

[0012] As a further scheme of the present invention: in the step five, the natural thickener is prepared by mixing extracellular polysaccharides produced by microbial fermentation and plant gum. Before use, the natural thickener is dried at 60°C-70°C for 2h-3h, and then crushed into a powder with a particle size of 50um-80um. The natural thickener is added to the mixed solution in an amount of 0.8%-1.2% of the total mass of the mixed solution. After adding, the mixed solution is continuously stirred, and the stirring speed is set to 200r / min-300r / min, and stirred for 20min-30min. Carbon dioxide gas is introduced into the mixed solution at a flow rate of 0.1L / min-0.2L / min. After stirring, the liquid fertilizer product is quality tested, including the nutrient content, microbial indicators and pH value of the liquid fertilizer product. After passing the test, the liquid fertilizer product is aseptically filled. The key sterility level of filling needs to reach Class A, that is, there is no more than 1 floating bacteria per cubic meter of air.

[0013] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. The present invention performs two filtering operations on the tryptophan fermentation waste liquid. The first filtering operation can remove suspended particles and macromolecular impurities in the waste liquid. The second filtering operation can remove macromolecular substances such as protein aggregates and polysaccharides in the waste liquid, and at the same time improve the light transmittance of the waste liquid and the recovery rate of tryptophan. When the tryptophan fermentation liquid is fermented in the fermentation tank, a low-frequency pulse electromagnetic field is applied to the fermentation tank, which can help enhance the permeability of the microbial cell membrane, promote the microbial uptake of substrates and the secretion of metabolites, and at the same time improve the fermentation efficiency and reduce the fermentation time of the tryptophan fermentation liquid. When adding a natural thickener, a trace amount of carbon dioxide gas is introduced into the solution, and the carbon dioxide gas forms tiny bubbles in the solution. The bubbles help the thickener to be better dispersed and form a stable network structure in the solution, which can further improve the viscosity and stability of the solution. By adding an antioxidant to the tryptophan fermentation waste liquid treatment solution and reacting, the antioxidant can be promoted to interact with the components in the solution to form a stable antioxidant system. The antioxidant system can reduce the degree of oxidation of the solution by more than 90% during subsequent treatment and storage, thereby improving the stability of tryptophan and other nutrients. 2. The present invention uses a nanofiltration membrane made of a multilayer nanostructured material and uses an ultrasonic generator to continuously act on the membrane surface during the nanofiltration process, which can effectively resist pollution and improve selectivity. It can ensure a high retention rate of tryptophan while removing small molecular impurities and some monovalent salt ions, and at the same time avoid concentration polarization and dirt deposition on the surface of the nanofiltration membrane, maintain the flux and performance of the nanofiltration membrane, extend the service life of the nanofiltration membrane, and reduce costs. In the ion exchange resin column, a polystyrene-divinylbenzene resin grafted with special functional groups is used, which has high selectivity for different ions. By using a composite enzyme preparation composed of a new glycoside hydrolase, a multifunctional oxidase and an aminopeptidase for enzymatic reaction, it can specifically identify and hydrolyze complex polysaccharide structures, catalyze oxidation reactions, improve amino acid release efficiency, promote full contact between enzymes and substrates, improve enzymatic efficiency, increase the yield of enzymatic products, further optimize the composition of liquid fertilizers, and promote plant absorption and utilization of nutrients. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the process of preparing liquid fertilizer from high-purity tryptophan 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 process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid, which comprises pretreatment of tryptophan fermentation liquid, concentration of fermentation waste liquid, component optimization and stabilization treatment. The specific operation steps of preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid are as follows: Step 1: collecting high-purity tryptophan fermentation waste liquid, filtering it using two sets of filter membranes, adjusting the pH value of the tryptophan fermentation waste liquid after filtration, adding a flocculant for precipitation, and taking the supernatant as the tryptophan fermentation waste liquid treatment liquid; Step 2: Treating the tryptophan fermentation waste liquid through a nanofiltration membrane, soaking the nanofiltration membrane before treatment, adding the treated waste liquid and the antioxidant mixture into a reactor and stirring after the treatment, and obtaining a tryptophan fermentation liquid after stirring; Step 3: Select a mixed microbial flora, inoculate and ferment the tryptophan fermentation liquid, add an enzyme preparation to the tryptophan fermentation liquid for enzymolysis after the fermentation is completed, and apply a low-frequency pulsed electromagnetic field for treatment, so as to obtain a tryptophan fermentation treatment liquid; Step 4: passing the tryptophan fermentation treatment liquid into an ion exchange resin column, collecting the ion exchange liquid and adding trace elements thereto to obtain a mixed solution; Step 5: Add the natural thickener to the mixed solution and continue stirring until the natural thickener is completely dispersed in the mixed solution to obtain a liquid fertilizer product. Take the liquid fertilizer product for quality monitoring. After passing the monitoring, fill it in a sterile environment.

[0017] In one embodiment of the present invention: in step 1, the temperature of the waste liquid is maintained at 20°C-22°C during the collection of high-purity tryptophan fermentation waste liquid. After the collection is completed, it is filtered using a graphene-ceramic composite microfiltration membrane with a pore size of 0.02um-0.03um. During the filtration process, the pressure is maintained at 0.12MPa-0.15MPa, the temperature is 20°C-25°C, and the filtration rate is controlled at 50L / h-60L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1kDa-2kDa, the pressure is controlled to 0.2MPa-0.25MPa, and the filtration is performed at a temperature of 22°C-25°C at a filtration rate of 30L / h-40L / h. After the filtration is completed, a composite pH regulator composed of a biological buffer and an organic acid is added to the filtrate to control the pH value of the tryptophan fermentation waste liquid between 4.0-4.2.

[0018] In one embodiment of the present invention: in step one, an inorganic composite flocculant is added to the tryptophan fermentation waste liquid, the inorganic composite flocculant is composed of extracellular polymers produced by microbial metabolism and nano-scale ferric hydroxide in a mass ratio of 3:2, and the amount of flocculant added is 0.4%-0.6% of the total volume of the tryptophan fermentation waste liquid. After adding the flocculant, stirring at a stirring rate of 40r / min-50r / min for 20min-25min, the flocculant and the tryptophan fermentation waste liquid are fully mixed, and allowed to stand for 80min-100min, and the supernatant after precipitation is taken to obtain a tryptophan fermentation waste liquid treated liquid.

[0019] In one embodiment of the present invention: in step 2, a nanofiltration membrane made of a multilayer nanostructured material is selected and soaked in a buffer solution containing specific electrolytes for 2h-3h before use. After completion, the tryptophan fermentation waste liquid treatment liquid is passed through the nanofiltration membrane at a flow rate of 8L / h-10L / h, and the operating pressure is controlled to be 0.32Mpa-0.38MPa, and the temperature is 25℃-28℃. During the nanofiltration process, an ultrasonic generator is installed on the outside of the nanofiltration membrane, and continuously acts on the surface of the nanofiltration membrane at a frequency of 20kHz-30kHz during the nanofiltration process.

[0020] In one embodiment of the present invention: in step 2, after nanofiltration is completed, an antioxidant mixture is added to the solution after nanofiltration, the antioxidant mixture is composed of a composite of bio-source antioxidant peptides, plant-source flavonoids and nanozymes, and the amount of the antioxidant mixture added is 0.35%-0.45% of the total mass of the solution after nanofiltration, the flow rate of the solution after nanofiltration is controlled to be 5L / h-8L / h, and the flow rate of the antioxidant mixture is 0.02L / h-0.03L / h. After the antioxidant mixture is uniformly dispersed in the solution after nanofiltration, the mixed solution is stirred at a temperature of 40°C-50°C and a speed of 800r / min-1000r / min for 8min-12min to obtain tryptophan fermentation broth.

[0021] In one embodiment of the present invention: in step three, the mixed microbial flora is prepared by mixing thermophilic Bacillus, Bacillus amyloliquefaciens, Lactobacillus plantarum and Rhodococcus in a quantitative ratio of 2:3:3:2, and the mixed microbial flora is inoculated into the tryptophan fermentation broth in a fermenter, and the inoculation amount is 6%-8% of the total volume of the tryptophan fermentation broth. The temperature is controlled between 32°C and 35°C during fermentation, and the pH value of the tryptophan fermentation broth is monitored in real time during fermentation. The dripping speed of the buffer solution is adjusted according to the pH value. The fermentation process lasts for 36h-48h. During the fermentation process, a low-frequency pulsed electromagnetic field is applied to the fermenter every 2h-3h, and the electromagnetic intensity is 0.5mT-1mT, the frequency is 5Hz-10Hz, and the duration of a single application of the low-frequency pulsed magnetic field is 10min-15min.

[0022] In one embodiment of the present invention: in step three, after the fermentation is completed, a composite enzyme preparation is added thereto, wherein the composite enzyme preparation is prepared by mixing glycoside hydrolase, multifunctional oxidase and aminopeptidase in a mass ratio of 3:2:1, and the total amount of the composite enzyme preparation added is 0.5%-0.7% of the mass of the fermentation liquid. During the enzymatic hydrolysis process, the temperature is controlled at 35°C-40°C, and the enzymatic hydrolysis reaction lasts for 12h-16h. After completion, a tryptophan fermentation treatment liquid is obtained.

[0023] In one embodiment of the present invention: in step 4, a novel ion exchange resin column is selected, wherein the internal resin is formed by grafting a polystyrene-divinylbenzene body with a special functional group, wherein the functional groups include carboxymethyl, aminophosphoric acid and thiol, and the ratio of the functional groups is 3:2:1, and the tryptophan fermentation treatment liquid is passed into the ion exchange resin column at a low flow rate of 2L / h-3L / h, and the operating temperature is controlled at 28°C-30°C. After passing through the ion exchange resin column, an ion exchange liquid is obtained, and trace elements are added thereto, including chelated zinc, boron, manganese, iron and molybdenum. Zinc, boron, manganese, iron and molybdenum are added in the form of sodium zinc ethylenediaminetetraacetate, sodium octaborate tetrahydrate, manganese glycine, sodium iron ethylenediaminetetraacetate and ammonium molybdate, and the added amounts are 2mg / L-3mg / L, 1mg / L-2mg / L, 0.5mg / L-1mg / L, 1mg / L-2mg / L and 0.1mg / L-0.2mg / L, respectively. After adding the trace elements and mixing, a mixed solution is obtained.

[0024] In one embodiment of the present invention: in step five, the natural thickener is prepared by mixing extracellular polysaccharides produced by microbial fermentation and plant gum. Before use, the natural thickener is dried at 60°C-70°C for 2h-3h, and then crushed into a powder with a particle size of 50um-80um. The natural thickener is added to the mixed solution in an amount of 0.8%-1.2% of the total mass of the mixed solution. After addition, the mixed solution is continuously stirred, and the stirring speed is set to 200r / min-300r / min, stirred for 20min-30min, and carbon dioxide gas is introduced into the mixed solution at a flow rate of 0.1L / min-0.2L / min. After stirring, the liquid fertilizer product is quality tested, including the nutrient content, microbial indicators and pH value of the liquid fertilizer product. After passing the test, the liquid fertilizer product is aseptically filled. The key sterility level of filling needs to reach Class A, that is, there is no more than 1 floating bacteria per cubic meter of air.

[0025] In one embodiment of the present invention: in step one, during the microfiltration process, an ultrasonic oscillation device may be arranged outside the filtration device, and the filtration device may be oscillated once every 10-15 minutes, and each oscillation lasts for 1-2 minutes, which can prevent the accumulation of impurities on the membrane surface. During the oscillation of the device, more than 80% of the suspended particles and macromolecular impurities in the waste liquid may be removed, and the turbidity of the tryptophan fermentation waste liquid may be reduced after primary filtration. When filtering through an ultrafiltration membrane, the ultrafiltration membrane is made of a three-dimensional mesh structure material, which can enhance the pressure resistance and stability of the membrane. During the filtration process, a small amount of inert gas is introduced into the waste liquid at a flow rate of 1 L / min-2 L / min. The inert gas can reduce the concentration difference polarization phenomenon on the membrane surface and improve the filtration effect. In this process, macromolecular substances such as protein aggregates and polysaccharides in the waste liquid can be removed, and the transmittance of the waste liquid is increased to more than 85%, and the recovery rate of tryptophan reaches more than 95%. The content of macromolecular substances in the waste liquid after secondary filtration is reduced to less than 10% of the original waste liquid.

[0026] In one embodiment of the present invention: in step one, the biological buffer is formed by mixing potassium dihydrogen phosphate and citric acid-sodium citrate buffer in a mass ratio of 2:1, and lactic acid is selected as the organic acid. Before adding the regulator, the waste liquid is first subjected to online component analysis, and the amount of the regulator added is accurately calculated by an intelligent algorithm based on the content of acid and alkaline substances in the waste liquid, and the composite pH regulator is slowly added to the waste liquid, and the waste liquid is high-purity tryptophan fermentation waste liquid.

[0027] In one embodiment of the present invention: the antioxidant mixture is composed of a composite of biogenic antioxidant peptides, plant-derived flavonoids and nanozymes. The biogenic antioxidant peptides are produced by fermentation of specific microorganisms, and their amino acid sequences have been screened and optimized to have high antioxidant activity. The plant-derived flavonoids are extracted and refined from elderberry. The nanozymes are nanomaterials with enzyme-like activity, specifically Prussian blue nanozymes with a particle size of 10nm-30nm, which can simulate the functions of natural antioxidant enzymes. The mass ratio of biogenic antioxidant peptides, plant-derived flavonoids and nanozymes is 4:3:3.

[0028] In one embodiment of the present invention: in step 4, before using the ion exchange resin column, the resin column is first rinsed with deionized water at a flow rate of 10L / h-15L / h for 30min-40min to remove impurities and possible residual chemicals on the surface of the resin, and then the resin column is pretreated with a mixed solution containing 0.1mol / L calcium chloride and 0.05mol / L magnesium chloride at a flow rate of 5L / h-8L / h for 30min-45min to fully expose and activate the active sites of the resin and improve the ion exchange efficiency.

[0029] Embodiment 1 When collecting high-purity tryptophan fermentation waste liquid, the waste liquid temperature is maintained at 20°C, and a graphene-ceramic composite microfiltration membrane with a pore size of 0.02um is used for filtration, and the filtration pressure is controlled to be 0.12MPa, the temperature is 20°C, and the filtration rate is 50L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1kDa, and the filtration pressure is controlled to be 0.2MPa, the temperature is 22°C, and the filtration rate is 30L / h. After that, a composite pH regulator is added to the filtrate. , adjusting the pH value of the tryptophan fermentation waste liquid to 4.0, wherein an inorganic composite flocculant is added to the tryptophan fermentation waste liquid, the addition amount is 0.4% of the total volume of the waste liquid, after the addition is completed, stirring is performed at a stirring rate of 40r / min for 20min, and then standing for 80min, and the supernatant is taken as the tryptophan fermentation waste liquid treatment liquid. During the microfiltration process, the outer side of the filter device is oscillated once every 10min with an ultrasonic oscillation device, and each time lasts for 1min. During ultrafiltration, an inert gas with a flow rate of 1L / min is introduced into the waste liquid; A nanofiltration membrane made of a multilayer nanostructured material composite is selected and immersed in a buffer solution containing a specific electrolyte for 2 hours. After the immersion is completed, the tryptophan fermentation waste liquid treatment solution passes through the nanofiltration membrane at a flow rate of 8L / h, the operating pressure is 0.32MPa, and the temperature is 25°C. During the nanofiltration process, an ultrasonic generator is installed on the outside of the membrane to continuously act on the surface of the nanofiltration membrane at a frequency of 20kHz. After nanofiltration, an antioxidant mixture is added to the solution, and the amount of the antioxidant mixture added is 0.35% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 5L / h, and the flow rate of the antioxidant mixture is 0.02L / h. The mixed solution is stirred at a temperature of 40°C and a speed of 800r / min for 8min to obtain a tryptophan fermentation liquid. The mixed microbial flora was inoculated into the tryptophan fermentation liquid, and the inoculation amount was 6% of the total volume of the fermentation liquid. The fermentation was carried out in a fermenter, and the temperature was controlled at 32°C. The pH value was monitored in real time. The dripping speed of the buffer solution was adjusted according to the pH value of the fermentation liquid. The fermentation process lasted for 36 hours. During the fermentation process, a low-frequency pulsed electromagnetic field (electromagnetic intensity of 0.5 mT, frequency of 5 Hz, and duration of 10 minutes) was applied to the fermenter every 2 hours. After the fermentation was completed, a composite enzyme preparation was added and mixed, and the addition amount was 0.5% of the mass of the fermentation liquid. The fermentation liquid was subjected to enzymatic hydrolysis reaction at 35°C for 12 hours to obtain a tryptophan fermentation treatment liquid. A new ion exchange resin column was selected, and the resin column was first rinsed with deionized water at a flow rate of 10 L / h for 30 minutes, and then pretreated with a mixed solution containing 0.1 mol / L calcium chloride and 0.05 mol / L magnesium chloride at a flow rate of 5 L / h for 30 minutes, and the tryptophan fermentation treatment liquid was passed into the ion exchange resin column at a flow rate of 2 L / h, and the operating temperature was 28° C. After collecting the ion exchange liquid, 2 mg / L of trace elements zinc in the form of sodium zinc ethylenediaminetetraacetate, 1 mg / L of boron in the form of sodium octaborate tetrahydrate, 0.5 mg / L of manganese in the form of manganese glycine, 1 mg / L of iron in the form of sodium ferric ethylenediaminetetraacetate, and 0.1 mg / L of molybdenum in the form of ammonium molybdate were added thereto to prepare a mixed solution; The natural thickener was dried at 60°C for 2h, crushed into a powder with a particle size of 50um, and added to the mixed solution in an amount of 0.8% of the total mass of the mixed solution. The mixture was stirred at a stirring speed of 200r / min for 20min. During the addition process, carbon dioxide gas was introduced at a flow rate of 0.1L / min. After stirring, a liquid fertilizer product was obtained.

[0030] Embodiment 2 When collecting high-purity tryptophan fermentation waste liquid, the waste liquid temperature is maintained at 21°C, and a graphene-ceramic composite microfiltration membrane with a pore size of 0.025um is used for filtration, and the filtration pressure is controlled to be 0.13MPa, the temperature is 23°C, and the filtration rate is 55L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1.5kDa, and the filtration pressure is controlled to be 0.22MPa, the temperature is 23°C, and the filtration rate is 35L / h. After that, a composite pH regulator is added to the filtrate. The pH value of the tryptophan fermentation waste liquid was adjusted to 4.1, wherein an inorganic composite flocculant was added to the tryptophan fermentation waste liquid in an amount of 0.5% of the total volume of the waste liquid, and after the addition was completed, the mixture was stirred at a stirring rate of 45 r / min for 22 minutes, and then allowed to stand for 90 minutes, and the supernatant was taken as the tryptophan fermentation waste liquid treatment liquid. During the microfiltration process, the outer side of the filter device was oscillated once every 12 minutes with an ultrasonic oscillation device, and each time lasted for 1.5 minutes. During ultrafiltration, an inert gas with a flow rate of 1.5 L / min was introduced into the waste liquid; A nanofiltration membrane made of a multilayer nanostructured material composite is selected and immersed in a buffer solution containing a specific electrolyte for 2.5 hours. After the immersion is completed, the tryptophan fermentation waste liquid treatment solution passes through the nanofiltration membrane at a flow rate of 9 L / h, the operating pressure is 0.35 MPa, and the temperature is 26°C. During the nanofiltration process, an ultrasonic generator is installed on the outside of the membrane to continuously act on the surface of the nanofiltration membrane at a frequency of 25 kHz. After nanofiltration, an antioxidant mixture is added to the solution, and the amount of the antioxidant mixture added is 0.4% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 6 L / h, and the flow rate of the antioxidant mixture is 0.025 L / h. The mixed solution is stirred at a temperature of 45°C and a speed of 900 r / min for 10 minutes to obtain a tryptophan fermentation liquid. The mixed microbial flora was inoculated into the tryptophan fermentation liquid, and the inoculation amount was 7% of the total volume of the fermentation liquid. The fermentation was carried out in a fermenter, and the temperature was controlled at 33°C. The pH value was monitored in real time. The dripping speed of the buffer solution was adjusted according to the pH value of the fermentation liquid. The fermentation process lasted for 42 hours. During the fermentation process, a low-frequency pulse electromagnetic field (electromagnetic intensity of 0.7 mT, frequency of 7 Hz, and duration of 12 minutes) was applied to the fermenter every 2.5 hours. After the fermentation was completed, a composite enzyme preparation was added and mixed in an amount of 0.6% of the mass of the fermentation liquid. The fermentation liquid was subjected to enzymatic hydrolysis at 37°C for 14 hours to obtain a tryptophan fermentation treatment liquid. A new ion exchange resin column was selected, and the resin column was first rinsed with deionized water at a flow rate of 12 L / h for 35 min, and then pretreated with a mixed solution containing 0.1 mol / L calcium chloride and 0.05 mol / L magnesium chloride at a flow rate of 6 L / h for 40 min, and the tryptophan fermentation treatment liquid was passed into the ion exchange resin column at a flow rate of 2.5 L / h, and the operating temperature was 29° C. After the ion exchange liquid was collected, trace elements were added thereto, and zinc was added in the form of 2.5 mg / L sodium zinc ethylenediaminetetraacetic acid, boron was added in the form of sodium octaborate tetrahydrate 1.5 mg / L, manganese was added in the form of manganese glycine 0.7 mg / L, iron was added in the form of sodium iron ethylenediaminetetraacetic acid 1.5 mg / L, and molybdenum was added in the form of ammonium molybdate 0.15 mg / L to prepare a mixed solution; The natural thickener was dried at 65°C for 2.5 hours and crushed into a powder with a particle size of 65 um. The thickener was added to the mixed solution in an amount of 1% of the total mass of the mixed solution. The mixture was stirred at a stirring speed of 250 r / min for 25 minutes. During the addition process, carbon dioxide gas was introduced at a flow rate of 0.15 L / min. After stirring, a liquid fertilizer product was obtained.

[0031] Embodiment 3 When collecting high-purity tryptophan fermentation waste liquid, the waste liquid temperature is maintained at 21.5°C, and a graphene-ceramic composite microfiltration membrane with a pore size of 0.028um is used for filtration, and the filtration pressure is controlled to be 0.14MPa, the temperature is 24°C, and the filtration rate is 58L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1.8kDa, and the filtration pressure is controlled to be 0.24MPa, the temperature is 24°C, and the filtration rate is 38L / h. After that, a composite pH regulator is added to the filtrate. The pH value of the tryptophan fermentation waste liquid was adjusted to 4.15, wherein an inorganic composite flocculant was added to the tryptophan fermentation waste liquid in an amount of 0.55% of the total volume of the waste liquid, and after the addition was completed, the mixture was stirred at a stirring rate of 48 r / min for 24 minutes, and then allowed to stand for 95 minutes, and the supernatant was taken as the tryptophan fermentation waste liquid treatment liquid. During the microfiltration process, the outer side of the filter device was oscillated once every 13 minutes with an ultrasonic oscillation device, and each time lasted for 1.8 minutes. During ultrafiltration, an inert gas with a flow rate of 1.8 L / min was introduced into the waste liquid; A nanofiltration membrane made of a multilayer nanostructured material composite is selected and immersed in a buffer solution containing a specific electrolyte for 2.8 hours. After the immersion is completed, the tryptophan fermentation waste liquid treatment solution passes through the nanofiltration membrane at a flow rate of 9.5L / h, the operating pressure is 0.36MPa, and the temperature is 27°C. During the nanofiltration process, an ultrasonic generator is installed on the outside of the membrane to continuously act on the surface of the nanofiltration membrane at a frequency of 28kHz. After nanofiltration, an antioxidant mixture is added to the solution, and the amount of the antioxidant mixture added is 0.42% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 7L / h, and the flow rate of the antioxidant mixture is 0.028L / h. The mixed solution is stirred at a temperature of 48°C and a speed of 950r / min for 11 minutes to obtain a tryptophan fermentation liquid. The mixed microbial flora was inoculated into the tryptophan fermentation liquid, and the inoculation amount was 7.5% of the total volume of the fermentation liquid. The fermentation was carried out in a fermenter, and the temperature was controlled at 34°C. The pH value was monitored in real time. The dripping speed of the buffer solution was adjusted according to the pH value of the fermentation liquid. The fermentation process lasted for 45 hours. During the fermentation process, a low-frequency pulsed electromagnetic field (electromagnetic intensity of 0.8 mT, frequency of 8 Hz, and duration of 13 minutes) was applied to the fermenter every 2.8 hours. After the fermentation was completed, a composite enzyme preparation was added and mixed, and the addition amount was 0.65% of the mass of the fermentation liquid. The fermentation liquid was subjected to enzymatic hydrolysis reaction at 38°C for 15 hours to obtain a tryptophan fermentation treatment liquid. A new ion exchange resin column was selected, and the resin column was first rinsed with deionized water at a flow rate of 13 L / h for 38 minutes, and then pretreated with a mixed solution containing 0.1 mol / L calcium chloride and 0.05 mol / L magnesium chloride at a flow rate of 7 L / h for 42 minutes, and the tryptophan fermentation treatment liquid was passed into the ion exchange resin column at a flow rate of 2.8 L / h, and the operating temperature was 29.5°C. After the ion exchange liquid was collected, trace elements were added thereto, and zinc was added in the form of 2.8 mg / L sodium zinc ethylenediaminetetraacetic acid, boron was added in the form of sodium octaborate tetrahydrate, 1.8 mg / L, manganese was added in the form of manganese glycine, 0.8 mg / L, iron was added in the form of sodium iron ethylenediaminetetraacetic acid, and molybdenum was added in the form of ammonium molybdate, 0.18 mg / L, to obtain a mixed solution; The natural thickener was dried at 68°C for 2.8 hours and crushed into a powder with a particle size of 70 um. The thickener was added to the mixed solution in an amount of 1.1% of the total mass of the mixed solution. The mixture was stirred at a stirring speed of 280 r / min for 28 minutes. During the addition process, carbon dioxide gas was introduced at a flow rate of 0.18 L / min. After stirring, a liquid fertilizer product was obtained.

[0032] Embodiment 4: When collecting high-purity tryptophan fermentation waste liquid, the waste liquid temperature is maintained at 22°C, and a graphene-ceramic composite microfiltration membrane with a pore size of 0.03um is used for filtration, and the filtration pressure is controlled to be 0.15MPa, the temperature is 25°C, and the filtration rate is 60L / h. After the filtration is completed, it is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 2kDa, and the filtration pressure is controlled to be 0.25MPa, the temperature is 25°C, and the filtration rate is 40L / h. After that, a composite pH regulator is added to the filtrate. The pH value of the tryptophan fermentation waste liquid is adjusted to 4.2, wherein an inorganic composite flocculant is added to the tryptophan fermentation waste liquid in an amount of 0.6% of the total volume of the waste liquid, and after the addition is completed, the mixture is stirred at a stirring rate of 50 r / min for 25 minutes, and then allowed to stand for 100 minutes, and the supernatant is taken as the tryptophan fermentation waste liquid treatment liquid. During the microfiltration process, the outer side of the filter device is oscillated once every 15 minutes with an ultrasonic oscillation device, and each time lasts for 2 minutes. During ultrafiltration, an inert gas with a flow rate of 2 L / min is introduced into the waste liquid; A nanofiltration membrane made of a multilayer nanostructured material composite is selected and immersed in a buffer solution containing a specific electrolyte for 3 hours. After the immersion is completed, the tryptophan fermentation waste liquid treatment solution is passed through the nanofiltration membrane at a flow rate of 10L / h, the operating pressure is 0.38MPa, and the temperature is 28°C. During the nanofiltration process, an ultrasonic generator is installed on the outside of the membrane to continuously act on the surface of the nanofiltration membrane at a frequency of 30kHz. After nanofiltration, an antioxidant mixture is added to the solution, and the amount of the antioxidant mixture added is 0.45% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 8L / h, and the flow rate of the antioxidant mixture is 0.03L / h. The mixed solution is stirred at a temperature of 50°C and a speed of 1000r / min for 12min to obtain a tryptophan fermentation liquid. The mixed microbial flora was inoculated into the tryptophan fermentation liquid, the inoculation amount was 8% of the total volume of the fermentation liquid, and the fermentation was carried out in a fermenter. The temperature was controlled at 35°C, and the pH value was monitored in real time. The dripping speed of the buffer solution was adjusted according to the pH value of the fermentation liquid. The fermentation process lasted for 48 hours. During the fermentation process, a low-frequency pulse electromagnetic field (electromagnetic intensity of 1 mT, frequency of 10 Hz, and duration of 15 minutes) was applied to the fermenter every 3 hours. After the fermentation was completed, a composite enzyme preparation was added and mixed in an amount of 0.7% of the mass of the fermentation liquid. The fermentation liquid was subjected to enzymatic hydrolysis at 40°C for 16 hours to obtain a tryptophan fermentation treatment liquid. A new ion exchange resin column was selected, and the resin column was first rinsed with deionized water at a flow rate of 15 L / h for 40 min, and then pretreated with a mixed solution containing 0.1 mol / L calcium chloride and 0.05 mol / L magnesium chloride at a flow rate of 8 L / h for 45 min, and the tryptophan fermentation treatment liquid was passed into the ion exchange resin column at a flow rate of 3 L / h, and the operating temperature was 30° C. After collecting the ion exchange liquid, trace elements were added thereto, and zinc was added in the form of 3 mg / L sodium zinc ethylenediaminetetraacetic acid, boron was added in the form of sodium octaborate tetrahydrate 2 mg / L, manganese was added in the form of manganese glycine 1 mg / L, iron was added in the form of sodium iron ethylenediaminetetraacetic acid 2 mg / L, and molybdenum was added in the form of ammonium molybdate 0.2 mg / L to prepare a mixed solution; The natural thickener was dried at 70°C for 3 hours, crushed into a powder with a particle size of 80 um, and added to the mixed solution in an amount of 1.2% of the total mass of the mixed solution. The mixture was stirred at a stirring speed of 300 r / min for 30 minutes. During the addition process, carbon dioxide gas was introduced at a flow rate of 0.2 L / min. After stirring, a liquid fertilizer product was obtained.

[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 content testing, Trace element content: Take an appropriate amount of liquid fertilizer product, filter it with a 0.45um filter membrane to remove possible suspended particles in it to prevent clogging of the sampling system and affecting the test results. Turn on the ICP-MS instrument and preheat it for 30-60 minutes. After the instrument is stable, use standard solutions containing known concentrations of trace elements such as zinc, boron, manganese, iron, and molybdenum for calibration. By adjusting the instrument's radio frequency power, nebulizer gas flow, sampling depth, etc., a good linear relationship is established between the detection signal intensity and concentration of the standard solution. Draw a standard curve and introduce the treated sample solution into the nebulizer of the ICP-MS. In the plasma torch, the sample is ionized to form gaseous ions. The ions are focused by the ion lens under a high vacuum environment and enter the mass analyzer, where they are separated and detected according to the mass-to-charge ratio (m / z) of different element ions. The contents of zinc, boron, manganese, iron and molybdenum in the samples were calculated according to the standard curve.

[0034] Microbiological index detection, Total bacterial count: Prepare a series of sterile saline dilution tubes, mark the dilution multiples, take 1 mL of liquid fertilizer and add it to 9 mL of sterile saline to make 10 -1 dilution, mix thoroughly, and then -1 Take 1mL of the dilution solution and add it to the next dilution tube. Prepare sample solutions of different dilutions by analogy. Select the appropriate culture medium according to the expected microbial species. For mixed bacterial flora such as thermophilic Bacillus, Bacillus amyloliquefaciens, Lactobacillus plantarum, and Rhodococcus, use nutrient agar medium (NA) or other suitable general culture medium. Heat and melt the culture medium, cool it to 45℃-50℃, and pour it into a sterile culture dish. Pour about 15mL-20mL into each culture dish and wait for it to solidify to form a plate. Take 0.1-0mL.2mL of the sample solution from each dilution, and spread it evenly on the surface of the corresponding plate with a sterile coating stick. Make 3 parallel plates for each dilution. Place the inoculated plates upside down in a constant temperature incubator. Choose the appropriate culture temperature and time according to the growth characteristics of different microorganisms. For the above mixed flora, culture at 30-37℃ for 24-48 hours. After the cultivation is completed, take out the plates, observe the growth of colonies, select the plates with colony counts between 30-300 for counting, calculate the number of colony forming units (CFU) on each plate, and calculate the total number of bacteria per milliliter of liquid fertilizer in the original sample based on the dilution multiple.

[0035] pH value detection: Turn on the pH meter and prepare at least two standard buffer solutions with different pH values ​​(pH4.00, pH6.86, pH9.18). Soak the electrode of the pH meter in a standard buffer solution with a pH value close to that of the sample. Follow the instrument manual to adjust the calibration knob to make the pH meter display consistent with the pH value of the standard buffer solution. Complete single-point or multi-point calibration. Rinse the electrode with deionized water, gently absorb the moisture on the surface of the electrode, and then insert the electrode into the finished liquid fertilizer, making sure that the electrode glass membrane is completely immersed in the sample. After the pH meter reading stabilizes, record the displayed pH value.

[0036] Embodiment 1 Trace element content, Zinc content: 2mg / L; Boron content: 1mg / L; Manganese content: 0.5mg / L; Iron content: 1mg / L; Molybdenum content: 0.1mg / L.

[0037] Total bacteria count, 35×10 5 CFU / mL.

[0038] pH value, pH: 6.5.

[0039] Embodiment 2 Trace element content, Zinc content: 2.5mg / L; Boron content: 1.5mg / L; Manganese content: 0.7mg / L; Iron content: 1.5 mg / L; Molybdenum content: 0.15mg / L.

[0040] Total bacteria count, 57×10 5 CFU / mL.

[0041] pH value, pH: 6.6.

[0042] Embodiment 3 Trace element content, Zinc content: 2.8 mg / L; Boron content: 1.8 mg / L; Manganese content: 0.8mg / L; Iron content: 1.8 mg / L; Molybdenum content: 0.18 mg / L.

[0043] Total bacteria count, 75×10 5 CFU / mL.

[0044] pH value, pH: 6.7.

[0045] Embodiment 4: Trace element content, Zinc content: 3mg / L; Boron content: 2mg / L; Manganese content: 1mg / L; Iron content: 2mg / L; Molybdenum content: 0.2mg / L.

[0046] Total bacteria count, 95×10 5 CFU / mL.

[0047] pH value, pH value: 6.8.

[0048] In summary, the feasibility and effectiveness of the continuous production process for preparing fertilizer from high-purity tryptophan fermentation waste liquid in the four groups of embodiments of the present invention have important practical significance and application value.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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 process for preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid, comprising pretreatment of tryptophan fermentation liquid, concentration of fermentation waste liquid, component optimization and stabilization treatment, characterized in that: The specific operation steps of preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid are as follows: Step 1: collecting high-purity tryptophan fermentation waste liquid, filtering it using two sets of filter membranes, adjusting the pH value of the tryptophan fermentation waste liquid after filtration, adding a flocculant for precipitation, and taking the supernatant as the tryptophan fermentation waste liquid treatment liquid; Step 2: treating the tryptophan fermentation waste liquid through a nanofiltration membrane, adding an antioxidant mixture after the treatment, and stirring and mixing to obtain a tryptophan fermentation liquid; Step 3: Select a mixed microbial flora, inoculate and ferment the tryptophan fermentation liquid, and after the fermentation is completed, add an enzyme preparation to perform an enzymatic hydrolysis reaction, and obtain a tryptophan fermentation treatment liquid; Step 4: passing the tryptophan fermentation treatment liquid into an ion exchange resin column, collecting the ion exchange liquid and adding trace elements thereto to obtain a mixed solution; Step 5: Add the natural thickener to the mixed solution and continue stirring until the natural thickener is completely dispersed in the mixed solution to obtain a liquid fertilizer product. Take the liquid fertilizer product for quality monitoring. After passing the monitoring, fill it in a sterile environment.

2. A process for preparing liquid fertilizer using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 1, the temperature of the waste liquid is maintained at 20°C-22°C during the collection of high-purity tryptophan fermentation waste liquid. After the collection is completed, the waste liquid is filtered using a graphene-ceramic composite microfiltration membrane with a pore size of 0.02um-0.03um. During the filtration process, the pressure is maintained at 0.12MPa-0.15MPa, the temperature is maintained at 20°C-25°C, and the filtration rate is controlled at 50L / h-60L / h. After the filtration is completed, the waste liquid is passed through a polyamide-carbon nanotube composite ultrafiltration membrane with a molecular weight cutoff of 1kDa-2kDa, the pressure is controlled at 0.2MPa-0.25MPa, and the filtration is performed at a temperature of 22°C-25°C at a filtration rate of 30L / h-40L / h. After the filtration is completed, a composite pH regulator composed of a biological buffer and an organic acid is added to the filtrate to control the pH value of the tryptophan fermentation waste liquid between 4.0 and 4.

2.

3. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 1, an inorganic composite flocculant is added to the tryptophan fermentation waste liquid, wherein the inorganic composite flocculant is composed of extracellular polymers produced by microbial metabolism and nano-scale ferric hydroxide in a mass ratio of 3:2, and the amount of the flocculant added is 0.4%-0.6% of the total volume of the tryptophan fermentation waste liquid. After the flocculant is added, stirring is performed at a stirring rate of 40r / min-50r / min for 20min-25min, the flocculant and the tryptophan fermentation waste liquid are fully mixed, and the mixture is allowed to stand for 80min-100min, and the supernatant after precipitation is taken to obtain a tryptophan fermentation waste liquid treatment liquid.

4. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 2, a nanofiltration membrane made of a multilayer nanostructured material is selected and soaked in a buffer solution containing a specific electrolyte for 2h-3h before use. After completion, the tryptophan fermentation waste liquid treatment liquid is passed through the nanofiltration membrane at a flow rate of 8L / h-10L / h, and the operating pressure is controlled to be 0.32Mpa-0.38MPa and the temperature is 25°C-28°C. During the nanofiltration process, an ultrasonic generator is installed on the outside of the nanofiltration membrane to continuously act on the surface of the nanofiltration membrane at a frequency of 20kHz-30kHz.

5. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 2, after the nanofiltration is completed, an antioxidant mixture is added to the solution after nanofiltration, the antioxidant mixture is composed of a composite of biological antioxidant peptides, plant flavonoids and nanozymes, and the amount of the antioxidant mixture added is 0.35%-0.45% of the total mass of the solution after nanofiltration. The flow rate of the solution after nanofiltration is controlled to be 5L / h-8L / h, and the flow rate of the antioxidant mixture is 0.02L / h-0.03L / h. After the antioxidant mixture is uniformly dispersed in the solution after nanofiltration, the mixed solution is stirred at a temperature of 40°C-50°C and a speed of 800r / min-1000r / min for 8min-12min to obtain tryptophan fermentation broth.

6. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step three, the mixed microbial flora is prepared by mixing thermophilic bacillus, bacillus amyloliquefaciens, lactobacillus plantarum and rhodococcus in a quantity ratio of 2:3:3:

2. The mixed microbial flora is inoculated into the tryptophan fermentation broth in a fermenter, and the inoculation amount is 6%-8% of the total volume of the tryptophan fermentation broth. The temperature is controlled between 32°C and 35°C during fermentation. The pH value of the tryptophan fermentation broth is monitored in real time during fermentation, and the dripping speed of the buffer solution is adjusted according to the pH value. The fermentation process lasts for 36h-48h. During the fermentation process, a low-frequency pulsed electromagnetic field is applied to the fermenter every 2h-3h, and the electromagnetic intensity is 0.5mT-1mT, the frequency is 5Hz-10Hz, and the duration of a single application of the low-frequency pulsed magnetic field is 10min-15min.

7. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step three, after the fermentation is completed, a composite enzyme preparation is added thereto, wherein the composite enzyme preparation is prepared by mixing glycoside hydrolase, multifunctional oxidase and aminopeptidase in a mass ratio of 3:2:1, and the total amount of the composite enzyme preparation added is 0.5%-0.7% of the mass of the fermentation liquid. During the enzymatic hydrolysis process, the temperature is controlled at 35°C-40°C, and the enzymatic hydrolysis reaction lasts for 12h-16h. After completion, a tryptophan fermentation treatment liquid is obtained.

8. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 4, a novel ion exchange resin column is selected, wherein the internal resin is formed by grafting a polystyrene-divinylbenzene body with a special functional group, wherein the functional groups include carboxymethyl, aminophosphoric acid and thiol, and the ratio of the functional groups is 3:2:1, and the tryptophan fermentation treatment liquid is passed into the ion exchange resin column at a low flow rate of 2L / h-3L / h, and the operating temperature is controlled at 28°C-30°C. After passing through the ion exchange resin column, an ion exchange liquid is obtained, and trace elements are added thereto, including chelated zinc, boron, manganese, iron and molybdenum. Zinc, boron, manganese, iron and molybdenum are added in the form of sodium zinc ethylenediaminetetraacetate, sodium octaborate tetrahydrate, manganese glycine, sodium iron ethylenediaminetetraacetate and ammonium molybdate, and the added amounts are 2mg / L-3mg / L, 1mg / L-2mg / L, 0.5mg / L-1mg / L, 1mg / L-2mg / L and 0.1mg / L-0.2mg / L, respectively. After adding the trace elements and mixing, a mixed solution is obtained.

9. The process for preparing liquid fertilizer by using high-purity tryptophan fermentation waste liquid according to claim 1, characterized in that: In the step 5, the natural thickener is prepared by mixing extracellular polysaccharides produced by microbial fermentation and plant gum. Before use, the natural thickener is dried at 60°C-70°C for 2h-3h, and then crushed into a powder with a particle size of 50um-80um. The natural thickener is added to the mixed solution in an amount of 0.8%-1.2% of the total mass of the mixed solution. After addition, the mixed solution is continuously stirred, and the stirring speed is set to 200r / min-300r / min, and stirred for 20min-30min. Carbon dioxide gas is introduced into the mixed solution at a flow rate of 0.1L / min-0.2L / min. After stirring, the liquid fertilizer product is quality tested, including the nutrient content, microbial indicators and pH value of the liquid fertilizer product. After passing the test, the liquid fertilizer product is aseptically filled. The key aseptic level of filling needs to reach Class A, that is, there is no more than 1 floating bacteria per cubic meter of air.

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