A method for removing impurities from cattle urine and application thereof in preparation of algal culture solution

Abstract

The application discloses a method for removing impurities from cow urine and application thereof in preparation of algal culture solution, and relates to the technical field of biological treatment. The method for removing impurities from cow urine adopts a multistage treatment system of chelating agent removal, activated carbon adsorption, physical filtration, composite microbial fermentation and precision filtration; the physical filtration adopts a stainless steel filter screen; the microbial fermentation adopts a composite microbial agent containing bacillus pasteurii, bacillus subtilis and lactobacillus plantarum; and the precision filtration adopts a microporous filter membrane. The application develops an efficient, environment-friendly and low-cost method for removing impurities from cow urine, removes macromolecular contaminant substances and harmful microorganisms and the like impurities in the cow urine, and meanwhile retains beneficial nutrient components in the cow urine; high-quality algal culture solution is prepared through the impurity-removed cow urine, the cost of the algal culture solution is reduced, and the nutrient components in the cow urine are fully utilized, so that abundant nutrient substances are provided for the growth of algae.

Description

Technical Field

[0001] This invention relates to the field of biological treatment technology, specifically to a method for removing impurities from cow urine and its application in the preparation of algal culture media. Background Technology

[0002] In recent years, with the increasingly widespread application of algae in food, medicine, energy and other fields, the development of efficient and low-cost algae culture media has become a research hotspot. Cow urine, as a natural resource rich in nitrogen, phosphorus, potassium and other nutrients, theoretically has the potential to be used as a raw material for algae culture media. However, cow urine has a complex composition, and if directly applied to algae cultivation, impurities will cause many problems.

[0003] Currently, common methods for removing impurities from cow urine include physical, chemical, and biological methods. Physical methods, such as filtration and centrifugation, can only remove larger particulate impurities and are ineffective at removing small molecule impurities and microorganisms dissolved in cow urine. Chemical methods, such as adding chemical reagents to precipitate impurities, can easily leave chemical residues and adversely affect the growth environment of algae. Biological methods, such as using microorganisms to degrade impurities, have the advantages of being environmentally friendly and efficient, but currently lack highly efficient microbial strains and mature treatment processes specifically targeting impurities in cow urine.

[0004] Despite the numerous challenges in removing impurities from cow urine, using purified cow urine to prepare algae culture media still offers significant advantages. Firstly, cow urine is widely available and inexpensive, reducing production costs and increasing economic efficiency. Secondly, the nutrients in cow urine are natural, abundant, and well-balanced, providing comprehensive nutritional support for algae growth and contributing to improved algae quality and yield.

[0005] This invention is proposed to solve the aforementioned problems in the removal and application of bovine urine impurities. By developing an efficient, environmentally friendly, and low-cost method for removing bovine urine impurities, this method removes macromolecular pollutants and harmful microorganisms from bovine urine while retaining beneficial nutrients, thereby preparing a high-quality algae culture medium and providing a new and feasible solution for algae cultivation. Summary of the Invention

[0006] The purpose of this invention is to provide a method for removing impurities from cow urine and its application in the preparation of algal culture media, so as to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A method for removing impurities from cow urine includes the following steps:

[0009] S1: Add chelating agent to fresh cow urine at a ratio of 0.5-1 g / L, and stir at 150-200 rpm for 30-60 minutes; add activated carbon at a ratio of 5-10 g / L, and stir at 150-200 rpm for 60-120 minutes to adsorb heavy metal complexes, precipitates, and organic matter; perform coarse filtration to remove precipitates with a particle size greater than 150 μm, and obtain the filtrate;

[0010] S2: Add compound microbial agent to the filtrate obtained from S1 for fermentation to degrade urea and protein, while inhibiting harmful microorganisms;

[0011] S3: Centrifuge the liquid obtained from S2 fermentation to remove suspended solids and tiny particles; filter it through a microporous membrane to remove bacteria and other microorganisms, finally obtaining purified cow urine.

[0012] Furthermore, the chelating agent in S1 is ethylenediaminetetraacetic acid (EDTA).

[0013] Furthermore, the activated carbon in S1 is powdered activated carbon with a particle size of 1-2 mm.

[0014] Furthermore, the coarse filter described in S1 uses a 100-200 mesh 304 stainless steel filter screen.

[0015] Furthermore, the compound microbial agent described in S2 contains Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum, and the mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum is (2-3):(1-2):(0.5-1).

[0016] Furthermore, the Bacillus pasteurellii has the accession number ATCC 11859, the Bacillus subtilis has the accession number CPCC 140552, and the Lactobacillus plantarum has the accession number CICC 23170.

[0017] Furthermore, the inoculation amount of the compound microbial agent described in S2 is 0.8-1.2 g / L of bovine urine.

[0018] Furthermore, the fermentation conditions described in S2 are: pH 6.5-7.5, temperature 25-35℃, rotation speed 150-200 rpm, and fermentation time 24-48 hours.

[0019] Furthermore, acetic acid or sodium bicarbonate can be used to adjust the pH value.

[0020] Furthermore, the centrifugation conditions described in S3 are: 3000-5000 rpm, centrifugation for 10-15 minutes.

[0021] Furthermore, the microporous filter membrane is a 0.22 μm polyethersulfone microporous filter membrane.

[0022] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0023] Step 1: Culture medium formula: 50-100 mL / L of purified bovine urine, 0.1-1 g / L of glucose, 0.25-0.75 g / L of sodium nitrate, 0.05-0.1 g / L of potassium dihydrogen phosphate, 0.07-0.1 g / L of magnesium sulfate, 0.03-0.05 g / L of calcium chloride, 0.006-0.01 g / L of citric acid, 0.001-0.003 g / L of disodium EDTA, 0.02-0.05 g / L of sodium carbonate, and 0.5-3 mL / L of trace element solution;

[0024] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0-8.0 to obtain the algae culture medium.

[0025] Furthermore, the trace element solution formula is as follows: boric acid 2-5 g / L, manganese chloride 1-3 g / L, sodium molybdate 0.3-0.5 g / L, zinc sulfate 0.2-0.5 g / L, copper sulfate 0.07-0.1 g / L, and cobalt nitrate 0.04-0.07 g / L.

[0026] Furthermore, when the algae culture medium is used for algae cultivation, the cultivation temperature is 20-30℃, the light intensity is 2000-4000 Lux, the light duration is 12-16 h / day, and the cultivation time is 3-7 days.

[0027] Furthermore, the algae are one or more of Spirulina, Scenedesmus, and Chlorella.

[0028] Furthermore, the removal of impurities from cow urine provides a nitrogen source for algal growth, while glucose provides a carbon source; the combination of the two enhances the algal cultivation effect.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are: the present invention adopts a multi-stage treatment system of chelating agent removal, activated carbon adsorption, physical filtration, compound microbial fermentation and precision filtration, which breaks through the limitations of traditional single methods.

[0030] The chelating agent of this invention can effectively remove heavy metals; the activated carbon particle size can adsorb heavy metal complexes, precipitates and organic matter; the 100-200 mesh stainless steel filter can effectively remove precipitates with a particle size greater than 150 μm.

[0031] In this invention, the compound microbial agent contains Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum working synergistically to degrade urea, break down proteins, and inhibit harmful microorganisms, resulting in a reduction of the total bacterial count by over 99.9% and more thorough removal of impurities.

[0032] This invention removes impurities while retaining mineral elements such as potassium and phosphorus in cow urine to the maximum extent. Furthermore, microbial fermentation transforms macromolecular nutrients into small molecular forms that are easily absorbed by algae, such as converting urea into ammonium ions and breaking down proteins into small peptides and amino acids, forming a nutrient structure that is more conducive to the absorption and utilization of algae and improving the efficiency of nutrient supply.

[0033] This invention uses cow urine, an agricultural waste, as a raw material to replace a large amount of chemically synthesized nutrients, significantly reducing the cost of algae culture medium; at the same time, it reduces environmental pollution caused by direct discharge of cow urine, realizing the resource utilization of waste.

[0034] In summary, this invention has developed an efficient, environmentally friendly, and low-cost method for removing impurities from cow urine. This method removes macromolecular pollutants and harmful microorganisms from cow urine while retaining beneficial nutrients. High-quality algae culture medium can be prepared from the purified cow urine, reducing the cost of algae culture medium and making full use of the nutrients in cow urine, such as nitrogen, phosphorus, and potassium, providing abundant nutrients for algae growth. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] In the following specific implementation:

[0037] The chelating agent is ethylenediaminetetraacetic acid (EDTA).

[0038] The activated carbon is in powder form, brand name YX-28, with a particle size of 1-2 mm.

[0039] The stainless steel filter screen is made of 304 stainless steel.

[0040] The compound microbial agent contains Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum. The preservation number of Bacillus pasteurellii is ATCC 11859, the preservation number of Bacillus subtilis is CPCC 140552, and the preservation number of Lactobacillus plantarum is CICC23170.

[0041] The microporous filter membrane is a 0.22μm polyethersulfone microporous filter membrane with a thickness of 120-140μm.

[0042] CAS number for ethylenediaminetetraacetic acid is 60-00-4; acetic acid is 64-19-7; sodium bicarbonate is 144-55-8; glucose is 50-99-7; sodium nitrate is 7632-00-0; potassium dihydrogen phosphate is 7778-77-0; magnesium sulfate is 7487-88-9; calcium chloride is 10043-52-4; citric acid is 77 -92-9; CAS number for disodium EDTA is 139-33-3; CAS number for sodium carbonate is 144-55-8; CAS number for boric acid is 10043-35-3; CAS number for manganese chloride is 7773-01-5; CAS number for sodium molybdate is 7631-95-0; CAS number for zinc sulfate is 7733-02-0; CAS number for copper sulfate is 7758-98-7; CAS number for cobalt nitrate is 13600-98-1.

[0043] Example 1: A method for removing impurities from cow urine, comprising the following steps:

[0044] S1: Add chelating agent to fresh cow urine at a ratio of 0.5 g / L and stir vigorously at 200 rpm for 30 minutes; add powdered activated carbon at a ratio of 5 g / L and stir at 150 rpm for 60 minutes to adsorb heavy metal complexes, precipitates, and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain the filtrate;

[0045] S2: Inoculate the filtrate obtained from S1 with a compound microbial agent for fermentation. The inoculum amount of the compound microbial agent is 0.8 g / L of cow urine. The fermentation conditions are: pH 6.5, temperature 25℃, rotation speed 150 rpm, and fermentation time 24 hours.

[0046] S3: The liquid obtained from S2 fermentation was centrifuged at 3000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0047] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 2:1:0.5.

[0048] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0049] Step 1: Culture medium formula: 50 mL / L of purified cow urine, 0.1 g / L of glucose, 0.25 g / L of sodium nitrate, 0.05 g / L of potassium dihydrogen phosphate, 0.07 g / L of magnesium sulfate, 0.03 g / L of calcium chloride, 0.006 g / L of citric acid, 0.001 g / L of disodium EDTA, 0.02 g / L of sodium carbonate, and 0.5 mL / L of trace element solution;

[0050] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0 to obtain the algae culture medium.

[0051] The trace element solution formula is as follows: boric acid 2g / L, manganese chloride 1g / L, sodium molybdate 0.3g / L, zinc sulfate 0.2g / L, copper sulfate 0.07g / L, and cobalt nitrate 0.04g / L.

[0052] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 20℃, the light intensity was 20000 Lux, the light duration was 12h / day, and the culture time was 3 days.

[0053] Example 2: A method for removing impurities from cow urine, comprising the following steps:

[0054] S1: Add chelating agent to fresh cow urine at a ratio of 0.5 g / L and stir vigorously at 200 rpm for 30 minutes; add powdered activated carbon at a ratio of 5 g / L and stir at 150 rpm for 60 minutes to adsorb heavy metal complexes, precipitates, and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain the filtrate;

[0055] S2: Inoculate the filtrate obtained from S1 with a compound microbial agent for fermentation. The inoculum amount of the compound microbial agent is 0.8 g / L of cow urine. The fermentation conditions are: pH 7.0, temperature 30℃, rotation speed 180 rpm, and fermentation time 36 hours.

[0056] S3: The liquid obtained from S2 fermentation was centrifuged at 4000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0057] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 2:1:1.

[0058] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0059] Step 1: Culture medium formula: 75 mL / L of purified cow urine, 0.5 g / L of glucose, 0.5 g / L of sodium nitrate, 0.08 g / L of potassium dihydrogen phosphate, 0.08 g / L of magnesium sulfate, 0.04 g / L of calcium chloride, 0.008 g / L of citric acid, 0.002 g / L of disodium EDTA, 0.04 g / L of sodium carbonate, and 2 mL / L of trace element solution;

[0060] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.5 to obtain the algae culture medium.

[0061] The trace element solution formula is as follows: boric acid 3g / L, manganese chloride 2g / L, sodium molybdate 0.4g / L, zinc sulfate 0.4g / L, copper sulfate 0.08g / L, and cobalt nitrate 0.05g / L.

[0062] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 25℃, the light intensity was 3000 Lux, the light duration was 14h / day, and the culture time was 5 days.

[0063] Example 3: A method for removing impurities from cow urine, comprising the following steps:

[0064] S1: Add chelating agent to fresh cow urine at a ratio of 0.5 g / L and stir vigorously at 200 rpm for 30 minutes; add powdered activated carbon at a ratio of 5 g / L and stir at 150 rpm for 60 minutes to adsorb heavy metal complexes, precipitates, and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain the filtrate;

[0065] S2: Inoculate the filtrate obtained from S1 with a compound microbial agent for fermentation. The inoculum amount of the compound microbial agent is 0.8 g / L of cow urine. The fermentation conditions are: pH 7.5, temperature 35℃, rotation speed 200 rpm, and fermentation time 48 hours.

[0066] S3: The liquid obtained from S2 fermentation was centrifuged at 5000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0067] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 3:2:1.

[0068] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0069] Step 1: Culture medium formula: 100 mL / L of purified cow urine, 1 g / L of glucose, 0.75 g / L of sodium nitrate, 0.1 g / L of potassium dihydrogen phosphate, 0.1 g / L of magnesium sulfate, 0.05 g / L of calcium chloride, 0.01 g / L of citric acid, 0.003 g / L of disodium EDTA, 0.05 g / L of sodium carbonate, and 3 mL / L of trace element solution;

[0070] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 8.0 to obtain the algae culture medium.

[0071] The trace element solution formula is as follows: boric acid 5g / L, manganese chloride 3g / L, sodium molybdate 0.5g / L, zinc sulfate 0.5g / L, copper sulfate 0.1g / L, and cobalt nitrate 0.07g / L.

[0072] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 30℃, the light intensity was 4000 Lux, the light duration was 16h / day, and the culture time was 7 days.

[0073] Comparative Example 1: Based on Example 1, the compound bacterial agent was adjusted to Bacillus pasteurellii, specifically including the following steps:

[0074] A method for removing impurities from cow urine includes the following steps:

[0075] S1: Add chelating agent to fresh cow urine at a ratio of 0.5 g / L and stir vigorously at 200 rpm for 30 minutes; add powdered activated carbon at a ratio of 5 g / L and stir at 150 rpm for 60 minutes to adsorb heavy metal complexes, precipitates, and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain the filtrate;

[0076] S2: Pasteurella multocida was inoculated into the filtrate obtained from S1 at an inoculum size of 0.8 g / L of bovine urine; the fermentation conditions were: pH 6.5, temperature 25℃, rotation speed 150 rpm, and fermentation time 24 hours.

[0077] S3: The liquid obtained from S2 fermentation was centrifuged at 3000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0078] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 2:1:0.5.

[0079] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0080] Step 1: Culture medium formula: 50 mL / L of purified cow urine, 0.1 g / L of glucose, 0.25 g / L of sodium nitrate, 0.05 g / L of potassium dihydrogen phosphate, 0.07 g / L of magnesium sulfate, 0.03 g / L of calcium chloride, 0.006 g / L of citric acid, 0.001 g / L of disodium EDTA, 0.02 g / L of sodium carbonate, and 0.5 mL / L of trace element solution;

[0081] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0 to obtain the algae culture medium.

[0082] The trace element solution formula is as follows: boric acid 2g / L, manganese chloride 1g / L, sodium molybdate 0.3g / L, zinc sulfate 0.2g / L, copper sulfate 0.07g / L, and cobalt nitrate 0.04g / L.

[0083] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 20℃, the light intensity was 20000 Lux, the light duration was 12h / day, and the culture time was 3 days.

[0084] Comparative Example 2: Based on Example 1, without the addition of a chelating agent, specifically including the following steps:

[0085] A method for removing impurities from cow urine includes the following steps:

[0086] S1: Add powdered activated carbon at a ratio of 5 g / L, stir at 150 rpm for 60 minutes to adsorb precipitates and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain filtrate;

[0087] S2: Inoculate the filtrate with a compound microbial agent for fermentation. The inoculation amount of the compound microbial agent is 0.8 g / L of cow urine. The fermentation conditions are: pH 6.5, temperature 25℃, rotation speed 150 rpm, and fermentation time 24 hours.

[0088] S3: The liquid obtained from S2 fermentation was centrifuged at 3000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0089] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 2:1:0.5.

[0090] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0091] Step 1: Culture medium formula: 50 mL / L of purified cow urine, 0.1 g / L of glucose, 0.25 g / L of sodium nitrate, 0.05 g / L of potassium dihydrogen phosphate, 0.07 g / L of magnesium sulfate, 0.03 g / L of calcium chloride, 0.006 g / L of citric acid, 0.001 g / L of disodium EDTA, 0.02 g / L of sodium carbonate, and 0.5 mL / L of trace element solution;

[0092] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0 to obtain the algae culture medium.

[0093] The trace element solution formula is as follows: boric acid 2g / L, manganese chloride 1g / L, sodium molybdate 0.3g / L, zinc sulfate 0.2g / L, copper sulfate 0.07g / L, and cobalt nitrate 0.04g / L.

[0094] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 20℃, the light intensity was 20000 Lux, the light duration was 12h / day, and the culture time was 3 days.

[0095] Comparative Example 3: Based on Example 1, the algae culture medium formula was adjusted without adding glucose, specifically including the following steps:

[0096] A method for removing impurities from cow urine includes the following steps:

[0097] S1: Add chelating agent to fresh cow urine at a ratio of 0.5 g / L and stir vigorously at 200 rpm for 30 minutes; add powdered activated carbon at a ratio of 5 g / L and stir at 150 rpm for 60 minutes to adsorb heavy metal complexes, precipitates, and organic matter; use a 100-mesh stainless steel filter to coarsely filter and remove precipitates with a particle size greater than 150 μm to obtain the filtrate;

[0098] S2: Inoculate the filtrate with a compound microbial agent for fermentation. The inoculation amount of the compound microbial agent is 0.8 g / L of cow urine. The fermentation conditions are: pH 6.5, temperature 25℃, rotation speed 150 rpm, and fermentation time 24 hours.

[0099] S3: The liquid obtained from S2 fermentation was centrifuged at 3000 rpm for 10 minutes and filtered through a 0.22 μm polyethersulfone microporous membrane to obtain purified cow urine.

[0100] The mass ratio of Bacillus pasteurellii, Bacillus subtilis, and Lactobacillus plantarum in the compound microbial agent is 1.5:0.5:0.5.

[0101] An application of purified cow urine in the preparation of algal culture medium, wherein the algal culture medium is prepared through the following steps:

[0102] Step 1: Culture medium formula: 50 mL / L of purified cow urine, 0.25 g / L of sodium nitrate, 0.05 g / L of potassium dihydrogen phosphate, 0.07 g / L of magnesium sulfate, 0.03 g / L of calcium chloride, 0.006 g / L of citric acid, 0.001 g / L of disodium EDTA, 0.02 g / L of sodium carbonate, and 0.5 mL / L of trace element solution;

[0103] Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0 to obtain the algae culture medium.

[0104] The trace element solution formula is as follows: boric acid 2g / L, manganese chloride 1g / L, sodium molybdate 0.3g / L, zinc sulfate 0.2g / L, copper sulfate 0.07g / L, and cobalt nitrate 0.04g / L.

[0105] When the algae culture medium was used to cultivate Chlorella, the culture temperature was 20℃, the light intensity was 20000 Lux, the light duration was 12h / day, and the culture time was 3 days.

[0106] Experiment: Fresh cow urine, and the purified cow urine from Examples 1-3 and Comparative Examples 1-3 were tested. The test indicators included urea content, protein content, free ammonia content, and microbial count. The results are shown in Table 1.

[0107] The urea content was determined using a Hitachi 7180 fully automated biochemical analyzer with a wavelength set to 546 nm, a reaction temperature of 37 °C, and a reaction time of 10 minutes.

[0108] A UV-2450 spectrophotometer was used with a wavelength set to 595 nm. After the sample was mixed with Coomassie Brilliant Blue reagent, the reaction time was 5 minutes, and then the absorbance was measured at this wavelength to calculate the protein content.

[0109] The free ammonia content was directly determined using the Leici DWG-8002A ammonia nitrogen automatic monitor via the ammonia-sensitive electrode method.

[0110] The plate count method was used to detect the number of microorganisms.

[0111] Table 1. Indicators of fresh cow urine and cleaned cow urine

[0112] Urea (g / L) Protein (mg / L) Free ammonia (mg / L) Microorganisms (CFU / mL) Fresh cow urine 1.1 115 85 <![CDATA[1.57×10 6 ]]> Example 1 0.08 23 230 270 Example 2 0.1 27 240 285 Example 3 0.07 25 245 278 Comparative Example 1 0.35 73 125 286 Comparative Example 2 0.15 38 210 297 Comparative Example 3 0.09 28 235 288

[0113] Conclusion: The data in the table show that in Comparative Example 1, adjusting the compound bacterial agent to Bacillus pasteurellii significantly increased the urea and protein content; in Comparative Example 2, the absence of chelating agents to adsorb heavy metals had some impact on the urea and protein content; and in Comparative Example 3, the absence of glucose in the algae culture medium had little impact on the various indicators.

[0114] Algae cultured in Examples 1-3 and Comparative Examples 1-3 were collected, and their biomass, chlorophyll a, and chlorophyll b contents were measured. The results are shown in Table 2.

[0115] The cultured algal solution was centrifuged at 4000 rpm for 10 minutes using an Eppendorf 5810R centrifuge. The precipitate was collected, placed in a Memmert UN 160 oven, dried at 105°C for 24 hours, and weighed using a Mettler Toledo ME204E analytical balance to determine the algal biomass.

[0116] Chlorophyll a was detected at a wavelength of 665 nm and chlorophyll b was detected at a wavelength of 649 nm using a UV-2102PC ultraviolet spectrophotometer.

[0117] Table 2. Algal biomass, chlorophyll a and chlorophyll b content

[0118] Biomass (mg / L) Chlorophyll a (mg / L) Chlorophyll b (mg / L) Example 1 2365 3.75 1.87 Example 2 2760 4.28 2.25 Example 3 2950 4.62 2.43 Comparative Example 1 1550 1.82 0.95 Comparative Example 2 1170 1.64 0.78 Comparative Example 3 2080 2.56 1.45

[0119] Conclusion: The data in the table show that in Comparative Example 1, adjusting the compound bacterial agent to Bacillus pasteurization significantly reduced algal biomass and the contents of chlorophyll a and chlorophyll b; in Comparative Example 2, without adding a chelating agent to adsorb heavy metals, algal biomass and the contents of chlorophyll a and chlorophyll b significantly reduced; and in Comparative Example 3, without adding glucose to the algal culture medium, algal biomass and the contents of chlorophyll a and chlorophyll b decreased.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for removing impurities from cow urine, characterized in that: Includes the following steps: S1: Add chelating agent to fresh cow urine at a ratio of 0.5-1 g / L, and stir at a speed of 150-200 rpm for 30-60 minutes; add activated carbon at a ratio of 5-10 g / L, and stir and adsorb at a speed of 150-200 rpm for 60-120 minutes; perform coarse filtration to obtain filtrate; S2: Inoculate the filtrate obtained in S1 with a compound microbial agent for fermentation; the compound microbial agent contains Bacillus pasteurellii, Bacillus subtilis and Lactobacillus plantarum. S3: Centrifuge the liquid obtained from S2 fermentation; filter it through a microporous membrane to finally obtain purified cow urine.

2. The method for removing impurities from cow urine according to claim 1, characterized in that: The coarse filter described in S1 uses a 100-200 mesh stainless steel filter screen.

3. The method for removing impurities from cow urine according to claim 1, characterized in that: The mass ratio of Bacillus pasteurellii, Bacillus subtilis and Lactobacillus plantarum in S2 is (2-3):(1-2):(0.5-1).

4. The method for removing impurities from cow urine according to claim 3, characterized in that: The inoculation amount of the compound microbial agent described in S2 is 0.8-1.2 g / L of bovine urine.

5. The method for removing impurities from cow urine according to claim 4, characterized in that: The fermentation conditions described in S2 are: pH 6.5-7.5, temperature 25-35℃, rotation speed 150-200 rpm, and fermentation time 24-48 hours.

6. The method for removing impurities from cow urine according to claim 1, characterized in that: The centrifugation conditions described in S3 are: 3000-5000 rpm, centrifugation for 10-15 minutes.

7. The method for removing impurities from cow urine according to claim 6, characterized in that: The microporous filter membrane described in S3 is a 0.22μm polyethersulfone microporous filter membrane.

8. The application of purified cow urine prepared by the purification method according to any one of claims 1-7 in the preparation of algal culture medium, characterized in that: The algae culture medium is prepared through the following steps: Step 1: Culture medium formula: 50-100 mL / L of purified bovine urine, 0.1-1 g / L of glucose, 0.25-0.75 g / L of sodium nitrate, 0.05-0.1 g / L of potassium dihydrogen phosphate, 0.07-0.1 g / L of magnesium sulfate, 0.03-0.05 g / L of calcium chloride, 0.006-0.01 g / L of citric acid, 0.001-0.003 g / L of disodium EDTA, 0.02-0.05 g / L of sodium carbonate, and 0.5-3 mL / L of trace element solution; Step 2: Culture medium preparation: Mix the above ingredients according to the formula ratio, add an appropriate amount of distilled water, stir evenly, and adjust the pH value to 7.0-8.0 to obtain the algae culture medium.

9. The application of the purified cow urine according to claim 8 in the preparation of algal culture medium, characterized in that: The trace element solution formula is as follows: boric acid 2-5 g / L, manganese chloride 1-3 g / L, sodium molybdate 0.3-0.5 g / L, zinc sulfate 0.2-0.5 g / L, copper sulfate 0.07-0.1 g / L, and cobalt nitrate 0.04-0.07 g / L.

10. The application of the purified cow urine according to claim 8 in the preparation of algal culture medium, characterized in that: When the algae culture medium is used for algae cultivation, the cultivation temperature is 20-30℃, the light intensity is 2000-4000 Lux, the light duration is 12-16 h / day, and the cultivation time is 3-7 days.