CN113637301B - Degradable microorganism nutrition sustained-release microsphere and preparation method and application thereof - Google Patents

Degradable microorganism nutrition sustained-release microsphere and preparation method and application thereof Download PDF

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CN113637301B
CN113637301B CN202111029605.XA CN202111029605A CN113637301B CN 113637301 B CN113637301 B CN 113637301B CN 202111029605 A CN202111029605 A CN 202111029605A CN 113637301 B CN113637301 B CN 113637301B
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modified starch
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microorganisms
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CN113637301A (en
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干建文
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Zhejiang Beroot Environmental Protection Technology Co ltd
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    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
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    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
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    • C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
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    • C08K3/32—Phosphorus-containing compounds
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Abstract

The invention relates to the field of sewage treatment, in particular to degradable microbial nutrition slow release microspheres and a preparation method and application thereof, wherein the degradable microbial nutrition slow release microspheres comprise the following components in parts by weight: 30-50 parts of polylactic acid, 20-40 parts of polyhydroxyalkanoate, 15-30 parts of modified starch granules, 5-15 parts of ammonium polyphosphate and 0.5-2 parts of ammonium molybdate. The degradable microorganism nutrition slow-release microspheres can be degraded by microorganisms in water, so that a carbon source and a phosphorus source required by growth are provided for the microorganisms, the activity of the microorganisms and the treatment efficiency of high ammonia nitrogen sewage are effectively ensured, meanwhile, a liquid nutritional agent which takes effect quickly but has a high decomposition speed and the degradable microorganism nutrition slow-release microspheres which take effect slowly but has a long duration are compounded, and the obtained strain nutrition compound agent can effectively ensure that the nutrition of the microorganisms can be continuously ensured in the whole process of sewage treatment.

Description

Degradable microorganism nutrition sustained-release microsphere and preparation method and application thereof
Technical Field
The invention relates to the field of sewage treatment, in particular to degradable microbial nutrition sustained-release microspheres and a preparation method and application thereof.
Background
The high ammonia nitrogen wastewater mainly comes from fertilizers, coking, petrifaction, pharmacy, foods, refuse landfills and the like. The method is characterized in that the eutrophication of the water body is easily caused by the discharged water body, the black and odorous water body is caused, and even the toxic action is generated on people and organisms, so the treatment difficulty of the high ammonia nitrogen wastewater is higher.
Because the concentration of ammonia nitrogen in the wastewater is high, the nitrogen source required by biological purification is excessive, so that the normal activity of microorganisms is influenced, the microorganisms are inactivated after being impacted by toxic and harmful substances, the treatment effect is seriously influenced, and the treated water exceeds the national discharge standard.
In the prior art, a certain amount of carbon source substances (usually in the form of nutrient solution) is usually added into the wastewater to ensure the normal growth of microorganisms, so as to improve the sewage treatment efficiency.
However, the nutrient (e.g. glucose) in the added nutrient solution is usually consumed at a fast rate, and once the concentration of the nutrient decreases, the activity of the microorganisms decreases, so that a larger amount of the nutrient solution needs to be added in multiple times in the wastewater treatment process to ensure that the microorganisms are always at a higher activity level. Meanwhile, in the biochemical treatment process, a specially-assigned person is required to check the consumption of the nutrient components in the water all the time, and the nutrient components are required to be supplemented and added in time when needed, so that the labor cost is greatly increased by the multi-adding mode.
For example, the application number is CN202110434008.9, the microbial nutrient solution for sewage treatment and the preparation method and the application thereof are disclosed, the nutrient solution is prepared by the following raw materials through secondary fermentation: papaya, apple, mango and lemon. The preparation method of the microbial nutrient solution comprises the following steps: weighing fruits in proportion and cleaning; sterilizing, washing and dicing; juicing to obtain coarse pulp; carrying out aerobic fermentation on the coarse pulp to obtain a fermentation stock solution; mixing; anaerobic fermentation to obtain mixed fermentation liquor, and filtering to obtain filtrate; the filtrate was mixed with deionized water. The microbial nutrient solution can promote the rapid growth and proliferation of microbes for pollution treatment, thereby obviously improving the efficiency of sewage treatment, but the actual sewage treatment by deammoniation and denitrification needs at least one month, so the highest efficiency can be achieved by supplementing the microbes for multiple times.
Disclosure of Invention
The invention provides a degradable microbial nutrition slow-release microsphere, a preparation method and application thereof, aiming at overcoming the defects that in the prior art, the consumption rate of nutritional ingredients in a microbial nutrient solution for treating high ammonia nitrogen wastewater is high, and the nutritional ingredients need to be added for multiple times.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 30-50 parts of polylactic acid, 20-40 parts of polyhydroxyalkanoate, 15-30 parts of modified starch granules, 5-15 parts of ammonium polyphosphate and 0.5-2 parts of ammonium molybdate;
wherein: the modified starch granules are internally silane-coupled modified starch granules, and a layer of polydopamine is wrapped outside the starch granules.
The main materials of the degradable microorganism nutrition slow release microsphere are polylactic acid and polyhydroxyalkanoate, and the polylactic acid and the polyhydroxyalkanoate are both materials with excellent biocompatibility and biodegradability. The polylactic acid is prepared by taking starch extracted from corn, wheat, cassava and other plants as an initial raw material, performing enzymatic decomposition to obtain glucose, performing lactic acid fermentation to form lactic acid, and performing chemical synthesis to obtain the polylactic acid. Polyhydroxyalkanoate (PHA) polyhydroxyalkanoate is an intracellular polyester synthesized by many bacteria, and is present in the living body mainly as a storage substance of a carbon source and an energy source. Therefore, the small molecule substances formed by the two substances in the biodegradation process can serve as a carbon source and are utilized and absorbed by microorganisms.
According to the invention, polylactic acid and polyhydroxyalkanoate are used as matrixes to prepare the degradable microorganism nutrition slow-release microspheres, and the degradable microorganism nutrition slow-release microspheres are decomposed under the decomposition action of microorganisms, so that carbon source support is provided for the microorganisms, and convenience is provided for the treatment of high ammonia nitrogen wastewater.
However, in the actual process, the researchers of the same people find that although polylactic acid and polyhydroxyalkanoate have the advantage of degradability, the initial degradation speed is slow, so that the polylactic acid and polyhydroxyalkanoate can not provide enough carbon source for the microorganisms in the initial stage of water treatment. Therefore, a certain amount of starch granules are added into the matrix material, and the starch granules can be used for rapidly providing a carbon source for microorganisms at the initial stage of water treatment, so that the capability of the microorganisms for treating high ammonia nitrogen wastewater is improved. However, the conventional starch is dissolved in water, so that the starch is lost in the flowing process of water flow, and the problem of low utilization rate is caused. Therefore, the starch granules are modified, and the starch granules are firstly modified through silane coupling, so that the starch is fixed, and the utilization rate of microorganisms can be effectively improved in the process of decomposing the starch. Meanwhile, the outer part of the starch granules is wrapped with a layer of polydopamine, the fixability of the polydopamine to starch can be further improved, and holes can be punched by microorganisms in the gradual degradation process of the polydopamine due to biodegradability of the polydopamine, so that the microorganisms can conveniently absorb the starch.
In the later stage of water treatment, because the degradation of the polylactic acid and the polyhydroxyalkanoate belongs to chain degradation, the polylactic acid and the polyhydroxyalkanoate can provide enough carbon sources for microorganisms in the later stage of water treatment along with the progress of degradation reaction.
Therefore, the invention uses the combination of the rapid carbon source (modified starch granules) and the slow carbon source (polylactic acid and polyhydroxyalkanoate) in the process of providing the carbon source for the microorganisms, and can ensure that the concentration of the carbon source for the growth of the microorganisms can be always kept stable in the whole period of water treatment, thereby realizing that the whole-process growth of the microorganisms can be met by adding the carbon source once.
Meanwhile, a certain amount of ammonium polyphosphate is added into the components, and can provide necessary phosphorus sources and nitrogen sources for microorganisms, so that the growth of the microorganisms is met. Compared with phosphate with small molecular weight (such as sodium monohydrogen phosphate, sodium dihydrogen phosphate and the like), the ammonium polyphosphate can provide a continuous phosphorus source for the microorganisms, so that the phosphorus content in the aqueous solution can be always in the concentration most suitable for the growth of the microorganisms, and the reactivity of the microorganisms can be effectively improved.
As mentioned above, the degradation speed of polylactic acid and polyhydroxyalkanoate is slow, and it is usually measured by researchers of this company that the polylactic acid needs 3 to 6 months under natural conditions to be degraded, while the time for wastewater treatment is usually about one month, and this slow degradation speed is difficult to meet the requirement of the microorganism on the carbon source. Therefore, in order to regulate the degradation rate of the two materials, researchers of the company especially add a certain amount of ammonium molybdate in the components, wherein the ammonium molybdate has certain oxidizability, and molybdate ions obtained by hydrolysis after meeting water can oxidize polylactic acid and polyhydroxyalkanoate chain segments, so that the main chains of the polylactic acid and the polyhydroxyalkanoate chain segments are subjected to chain scission depolymerization, the degradation of the polylactic acid and the polyhydroxyalkanoate is accelerated, and a sufficient amount of carbon source support is provided for microorganisms at the later stage of water treatment.
Meanwhile, the oxidation performance of ammonium molybdate is mild, the ammonium molybdate can only perform oxidation chain scission on the main chain of the carbon chain of polylactic acid and polyhydroxyalkanoate, the growth of microorganisms can not be inhibited, and the addition of molybdate radical can also promote the growth of microorganisms, so that the reaction activity of the ammonium molybdate is stronger.
Preferably, the preparation method of the modified starch granules comprises the following steps:
(1) Adding tetraethoxysilane and trimethyl borate into an ethanol aqueous solution, and mixing and hydrolyzing to obtain silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate into the starch, drying and curing after uniformly mixing to obtain silane coupling modified starch particles;
(3) And then spraying dopamine aqueous solution on the surface of the silane coupling modified starch particles, and drying in the air atmosphere to obtain the modified starch particles.
The modified starch granules are firstly connected with each other through the reaction of starch and silane hydrolysate, wherein hydroxyl in the starch can react with silicon hydroxyl in the silane hydrolysate, so that the starch can be tightly connected and fixed through a silicon-oxygen chain segment structure. Meanwhile, tetraethoxysilane is selected as siloxane in the invention, and silicon dioxide hydrogel can be formed in the hydrolysis process instead of a siloxane structure with organic groups, so that the further pollution of the organic silicon structure to the wastewater to be treated can be effectively prevented.
However, because the silica hydrogel has a strong chain segment, under certain conditions, if the silica hydrogel firmly coats the starch, the absorption and utilization of the coated starch by microorganisms are completely blocked, so that part of the carbon source cannot be effectively utilized.
Therefore, the invention adds a certain amount of trimethyl borate into the silane hydrolysate, and the trimethyl borate can be mixed with tetraethoxysilane for hydrolysis, so that the polyborosiloxane is formed. In general, polyborosiloxanes are used in applications where they are resistant to high temperatures and have high mechanical strength. However, the polyborosiloxane prepared by the simple mixed hydrolysis method in the invention generally has poor hydrolysis resistance, and a group for inhibiting the hydrolysis does not exist in a polymer chain segment, so that the polyborosiloxane is unstable in an environment with high humidity and an aqueous solution, and is easy to hydrolyze and chain-break in a storage process, thereby limiting the practical application of the polyborosiloxane in other use scenes requiring strong mechanical properties and adhesive properties.
However, the present invention utilizes this characteristic to make certain hydrolytic chain-breaking sites exist in the silica structure for connecting the coated carbon powder. When the modified starch granules are completely coated by silicon dioxide containing boron atoms, the part of the coated modified starch granules can be subjected to chain scission of boron-oxygen-silicon chain segments under the action of an aqueous solution, so that the coated starch granules can be released, and the part of starch can be utilized by microorganisms. Meanwhile, boric acid formed after hydrolysis can be used as a trace element by microorganisms, so that the efficiency of the microorganisms on sewage treatment is improved.
Preferably, the mass ratio of the tetraethoxysilane to the trimethyl borate to the ethanol to the water in the step (1) is 10: (0.1 to 1): (20 to 30): (20 to 30), the hydrolysis temperature is 60 to 75 ℃, and the hydrolysis reaction time is 3 to 8h.
Preferably, the mass ratio of the starch to the silane hydrolysate in the step (2) is 100: (10 to 20) and the curing temperature is 85 to 105 ℃.
Preferably, the mass ratio of the silane-coupled modified starch particles to the dopamine aqueous solution in the step (3) is 100: (10 to 20), and the dopamine aqueous solution (0.5 to 2) mg/ml is dried at the temperature of 55 to 70 ℃.
A preparation method of degradable microorganism nutrition slow-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixture;
(S.2) extruding and granulating the mixture to obtain granules;
and (S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide into the high-pressure kettle to saturate the granulated material, then decompressing, foaming, cooling and shaping to obtain the degradable microbial nutrition slow-release microspheres.
The degradable microorganism nutrition slow release microspheres in the invention are prepared by first blending granulation and uniformly mixing all components to form small particles in the preparation process. However, the granules obtained by such ordinary granulation have a compact texture, and due to the high crystallization characteristics of polylactic acid and polyhydroxyalkanoate, it is difficult for water to enter the inside of the granules, so that the degradation rate of the whole granules is slow.
Therefore, after the granulated material is prepared, the granulated material is foamed, so that water can more easily enter the interior of the degradable microorganism nutrition slow-release microspheres.
Thereby bringing the following benefits:
firstly, the contact area of the sustained-release microspheres and water is increased, namely the contact area of microorganisms and the sustained-release microspheres is increased, so that the degradation speed of the microorganisms to the sustained-release microspheres is greatly increased;
secondly, after moisture enters the sustained-release microspheres, ammonium molybdate in the sustained-release microspheres can be contacted with water and decomposed into molybdate radicals, so that the oxidative decomposition effect on the sustained-release microspheres is improved;
thirdly, the rapid carbon source (modified starch granules) deeply buried in the granulated material can be rapidly separated out, so that the utilization of the modified starch granules by the microorganisms is accelerated, a sufficient carbon source is provided for the microorganisms at the early stage of sewage treatment, and the microbial activity in the whole water treatment process is stabilized.
Preferably, in the step (S.2), the extrusion temperature is 160 to 175 ℃.
Preferably, in the step (S.3), the pressure in the autoclave is 10 to 15MPa, the supercritical treatment temperature is 120 to 145 ℃, the supercritical treatment time is 20 to 60min, the temperature is reduced to 80 to 100 ℃ after the supercritical treatment is finished, the pressure is released, and the cooling is carried out in an ice water bath.
A strain nutrition compound agent suitable for high ammonia nitrogen wastewater comprises a liquid nutritional agent and degradable microorganism nutrition slow-release microspheres prepared by the method.
The strain nutrition compound agent comprises a liquid nutrient agent and degradable microorganism nutrition slow-release microspheres, wherein the nutrient components in the liquid nutrient agent are the same as those of a conventional nutrient solution, so that the strain nutrition compound agent can rapidly provide a required carbon source and a required phosphorus source for organisms in sewage after being added into high ammonia nitrogen sewage, the activity of the microorganisms can be maintained in the early stage of sewage treatment, and the problem of low sewage treatment efficiency caused by insufficient nutrients is solved.
Because the degradable microbial nutrition slow-release microspheres require a certain period of time in the early stage of sewage treatment, the carbon source and the phosphorus source dissolved out by degradation of the degradable microbial nutrition slow-release microspheres cannot guarantee the whole growth needs of microorganisms in the early stage of sewage treatment, and the decomposed nutritional ingredients are enough to guarantee the growth of the microorganisms in the later stage due to the improvement of the degradation speed.
Therefore, the nutrient compound agent of the invention effectively ensures that the nutrient requirement of microorganisms can be continuously ensured in the whole process of sewage treatment by compounding the liquid nutrient which takes effect quickly but has high decomposition speed and the degradable microorganism nutrient sustained-release microspheres which take effect slowly but have long duration. And the liquid nutritional agent and the degradable microorganism nutrition slow-release microspheres are added at the same time only at one time at the initial stage of sewage treatment without adding for many times, so that the labor cost is greatly reduced.
Preferably, the liquid nutritional microbial inoculum comprises the following components in percentage by mass: 30 to 40 parts of wheat bran, 20 to 30 parts of vinasse, 3 to 8 parts of sugar residues, 12 to 18 parts of starch, 3 to 8 parts of yeast extract, 0.5 to 2 parts of dipotassium hydrogen phosphate and 100 parts of water.
Therefore, the invention has the following beneficial effects:
(1) The degradable microorganism nutrition slow-release microspheres can be degraded by microorganisms in water, so that a carbon source and a phosphorus source required by growth are provided for the microorganisms, and the activity of the microorganisms and the treatment efficiency of high ammonia nitrogen sewage are effectively ensured;
(2) The degradable microorganism nutrition slow release microspheres have proper decomposition rate, and can provide enough nutrition support for microorganisms within the conventional sewage treatment time;
(3) The strain nutrition compound agent suitable for the high ammonia nitrogen wastewater is prepared by compounding the liquid nutritional agent which takes effect quickly but has a high decomposition speed and the degradable microorganism nutrition slow-release microspheres which take effect slowly but have a long duration, so that the requirement of continuously guaranteeing the nutrition of microorganisms in the whole process of sewage treatment is effectively guaranteed;
(4) Only the liquid nutritional agent and the degradable microorganism nutrition slow-release microspheres are added at the beginning of sewage treatment at one time, and multiple times of addition are not needed, so that the labor cost is greatly reduced.
Drawings
FIG. 1 is a graph showing the test result of the carbon releasing property of the degradable microorganism nutrient sustained-release microspheres in clear water.
Detailed Description
The invention is further described with reference to the drawings and the specific embodiments. Those skilled in the art will be able to practice the invention based on these descriptions. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.
Example 1
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 30 parts of polylactic acid, 20 parts of polyhydroxyalkanoate, 15 parts of modified starch particles, 5 parts of ammonium polyphosphate and 0.5 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.1 part of trimethyl borate are added into an ethanol water solution obtained by mixing 20 parts of ethanol and 20 parts of water, and the mixture is hydrolyzed for 8 hours at the temperature of 60 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 10% of that of the starch into the starch, uniformly mixing, and drying and curing at 85 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying 0.5mg/ml dopamine aqueous solution on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 10, drying at 55 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microbial nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate in a high-speed mixer to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulating temperature of 160 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 10MPa into the high-pressure kettle, heating to 120 ℃, performing supercritical treatment for 20min to ensure that the granulated material is saturated, then reducing the temperature to 80 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 2
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 50 parts of polylactic acid, 40 parts of polyhydroxyalkanoate, 30 parts of modified starch particles, 15 parts of ammonium polyphosphate and 2 parts of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, adding 10 parts of tetraethoxysilane and 1 part of trimethyl borate into an ethanol water solution obtained by mixing 30 parts of ethanol and 30 parts of water, and carrying out mixing hydrolysis for 3 hours at 75 ℃ to obtain a clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 20% of that of the starch into the starch, uniformly mixing, and drying and curing at 105 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 2mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and (20) drying at 70 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulating temperature of 175 ℃ to obtain granules;
(S.3) placing the granulated material in an autoclave, introducing supercritical carbon dioxide with the pressure of 15MPa into the autoclave, heating to 145 ℃, then carrying out supercritical treatment for 20min to ensure that the granulated material is saturated, then reducing the temperature to 100 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 3
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 35 parts of polylactic acid, 25 parts of polyhydroxyalkanoate, 20 parts of modified starch particles, 10 parts of ammonium polyphosphate and 1 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.5 part of trimethyl borate are added into an ethanol water solution obtained by mixing 25 parts of ethanol and 25 parts of water, and the mixture is hydrolyzed for 5 hours at 70 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 15% of that of the starch into the starch, uniformly mixing, and drying and curing at 100 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 1mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 15, drying at 60 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at a granulation temperature of 165 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 12MPa into the high-pressure kettle, heating the mixture to 125 ℃, performing supercritical treatment for 30min to saturate the granulated material, then reducing the temperature to 85 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 4
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 40 parts of polylactic acid, 30 parts of polyhydroxyalkanoate, 25 parts of modified starch particles, 10 parts of ammonium polyphosphate and 1 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.8 part of trimethyl borate are added into an ethanol water solution obtained by mixing 30 parts of ethanol and 20 parts of water, and the mixture is hydrolyzed for 5 hours at 70 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 16% of that of the starch into the starch, uniformly mixing, and drying and curing at 95 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 1mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 16, drying at 60 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at a granulation temperature of 165 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 12MPa into the high-pressure kettle, heating the mixture to 130 ℃, performing supercritical treatment for 40min to saturate the granulated material, then reducing the temperature to 95 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 5
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 45 parts of polylactic acid, 35 parts of polyhydroxyalkanoate, 25 parts of modified starch particles, 10 parts of ammonium polyphosphate and 1 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.5 part of trimethyl borate are added into an ethanol water solution obtained by mixing 25 parts of ethanol and 28 parts of water, and the mixture is hydrolyzed for 6 hours at 70 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 18% of that of the starch into the starch, uniformly mixing, and drying and curing at 90 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 1.8mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 15, drying at 65 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulating temperature of 170 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 14MPa into the high-pressure kettle, heating to 135 ℃, performing supercritical treatment for 45min to saturate the granulated material, then reducing the temperature to 100 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 6
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 32 parts of polylactic acid, 28 parts of polyhydroxyalkanoate, 26 parts of modified starch particles, 9 parts of ammonium polyphosphate and 1 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.4 part of trimethyl borate are added into an ethanol water solution obtained by mixing 24 parts of ethanol and 26 parts of water, and the mixture is hydrolyzed for 4 hours at 68 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 15% of that of the starch into the starch, uniformly mixing, and drying and curing at 95 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 1mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 16, drying at 60 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixture;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulation temperature of 172 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 12MPa into the high-pressure kettle, heating to 125 ℃, performing supercritical treatment for 50min to saturate the granulated material, then reducing the temperature to 90 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 7
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 45 parts of polylactic acid, 25 parts of polyhydroxyalkanoate, 30 parts of modified starch particles, 12 parts of ammonium polyphosphate and 1.5 parts of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, 10 parts of tetraethoxysilane and 0.8 part of trimethyl borate are added into an ethanol water solution obtained by mixing 30 parts of ethanol and 30 parts of water, and the mixture is hydrolyzed for 6 hours at 70 ℃ to obtain clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 16% of that of the starch into the starch, uniformly mixing, and drying and curing at 105 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying 0.8mg/ml dopamine aqueous solution on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 12, drying at 60 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixture;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulating temperature of 175 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 10MPa into the high-pressure kettle, heating to 140 ℃, performing supercritical treatment for 30min to ensure that the granulated material is saturated, then reducing the temperature to 90 ℃, releasing pressure and foaming at one moment, and then cooling and shaping in an ice-water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 8
A degradable microorganism nutrition slow release microsphere comprises the following components in parts by weight: 30 parts of polylactic acid, 40 parts of polyhydroxyalkanoate, 30 parts of modified starch particles, 10 parts of ammonium polyphosphate and 1 part of ammonium molybdate.
Wherein: the preparation method of the modified starch granules comprises the following steps:
(1) According to the mass fraction, adding 10 parts of tetraethoxysilane and 1 part of trimethyl borate into an ethanol water solution obtained by mixing 25 parts of ethanol and 25 parts of water, and carrying out mixed hydrolysis for 6 hours at 70 ℃ to obtain a clear and transparent silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate with the mass of 18% of that of the starch into the starch, uniformly mixing, and drying and curing at 90 ℃ to obtain silane coupling modified starch particles;
(3) And then spraying a dopamine aqueous solution with the concentration of 1mg/ml on the surface of the silane coupling modified starch particles, wherein the mass ratio of the silane coupling modified starch particles to the dopamine aqueous solution is 100: and 15, drying at 70 ℃ in air atmosphere to obtain modified starch granules.
A preparation method of degradable microorganism nutrition sustained-release microspheres comprises the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the blend in a double-screw extruder at the granulating temperature of 175 ℃ to obtain granules;
(S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide with the pressure of 12MPa into the high-pressure kettle, heating the mixture to 130 ℃, performing supercritical treatment for 30min to saturate the granulated material, then reducing the temperature to 90 ℃, releasing pressure and foaming instantly, and then cooling and shaping in an ice water bath to obtain the degradable microorganism nutrition slow-release microspheres.
Example 9
A strain nutrition compound agent suitable for high ammonia nitrogen wastewater comprises:
the degradable microbial nutrition sustained-release microspheres prepared in example 3;
and the liquid nutritional agent comprises the following components in percentage by mass: 30 parts of wheat bran, 20 parts of vinasse, 3 parts of sugar residues, 12 parts of starch, 3 parts of yeast extract, 0.5 part of dipotassium hydrogen phosphate and 100 parts of water.
Example 10
A strain nutrition compound agent suitable for high ammonia nitrogen wastewater comprises:
the degradable microorganism nutrition sustained-release microspheres prepared in example 4;
and the liquid nutritional agent comprises the following components in percentage by mass: 40 parts of wheat bran, 30 parts of vinasse, 8 parts of sugar residues, 18 parts of starch, 8 parts of yeast extract, 2 parts of dipotassium hydrogen phosphate and 80 parts of water.
Example 11
A strain nutrition compound agent suitable for high ammonia nitrogen wastewater comprises:
the degradable microorganism nutrition sustained-release microspheres prepared in example 3;
and the liquid nutritional agent comprises the following components in percentage by mass: 35 parts of wheat bran, 25 parts of vinasse, 5 parts of sugar residues, 15 parts of starch, 5 parts of yeast extract, 1 part of dipotassium hydrogen phosphate and 100 parts of water.
Example 12
A strain nutrition compound agent suitable for high ammonia nitrogen wastewater comprises:
the degradable microbial nutrition sustained-release microspheres prepared in example 6;
and the liquid nutritional agent comprises the following components in percentage by mass: 36 parts of wheat bran, 28 parts of vinasse, 5 parts of sugar residues, 14 parts of starch, 6 parts of yeast extract, 1 part of dipotassium hydrogen phosphate and 100 parts of water.
And (3) performance testing:
【1】 Testing of clear water carbon release characteristics of degradable microorganism nutrition sustained-release microspheres
The method comprises the following steps: taking the degradable microorganism nutrition sustained-release microspheres prepared in example 3 as an example, the degradable microorganism nutrition sustained-release microspheres are put into a distilled water pool (the mass ratio of the degradable microorganism nutrition sustained-release microspheres to distilled water is 1: 200), and then a sample is taken every day to test the COD concentration in the water for 30 days, and the results are shown in fig. 1.
As can be seen from FIG. 1, after the degradable microorganism nutrition slow-release microspheres are put into clear water, the COD concentration in the water is slowly increased within 1 to 5 days, the increase curve is gentle, and from day 6, the COD in the water is rapidly increased, which shows that the increase curve becomes steep, and the increase of the COD is gradually reduced again until the 25 th day.
【2】 Denitrification effect test of strain nutrition compound agent
The method comprises the following steps: the strain nutrition compound agent prepared in the example 11 is used for treating sewage actually generated in a landfill site in certain places in Hubei, the ammonia nitrogen value in the sewage is 680 mg/l, the COD value is 2300 mg/l, and the strain nutrition compound agent is obviously not suitable for the growth of activated sludge. Therefore, firstly, the domesticated activated sludge is added into the sewage, the adding concentration of the activated sludge is about 40%, and then the liquid nutrient and the microorganism degradation nutrient slow-release microspheres prepared in the example 11 are added.
Wherein: the liquid nutritional agent is added in the first four days of sewage treatment, the addition amount of the liquid nutritional agent is about ten times of the COD value of the sewage before the sewage enters the tank A, and the liquid nutritional agent does not need to be added into the sewage again from the 5 th day;
the degradable microorganism nutrition slow-release microspheres are added in the first day, and the adding amount of the degradable microorganism nutrition slow-release microspheres is 0.5 to 1 percent of the mass of the A pool sewage.
Continuously performing water treatment for 30 days, and detecting the COD and ammonia nitrogen content in the sewage treated by the A pool and the O pool and the COD and ammonia nitrogen content in the water treated by ultrafiltration and reverse osmosis every day, wherein the test results are shown in the following table 1.
TABLE 1
Figure DEST_PATH_IMAGE002
From the data in the above table, it can be seen that the wastewater is more suitable for the growth of microorganisms in the activated sludge by adding a liquid nutrient to the high ammonia nitrogen wastewater 3 days before the wastewater is treated to supplement the carbon source of the whole wastewater. After AO treatment, ultrafiltration effluent and reverse osmosis effluent, the ammonia nitrogen content in the final treated water is greatly reduced.
From day 5, under the condition that no liquid nutritional agent is added, the degradable microorganism nutrition slow-release microspheres are decomposed to obtain a carbon source which can support the nutrition requirement required by the growth of microorganisms, and after comparing the data with the data of the previous 4 days, the ammonia nitrogen content in the water obtained by final treatment is found to be closer to the ammonia nitrogen content in the previous 4 days, which shows that the degradable microorganism nutrition slow-release microspheres can release enough carbon source under the decomposition action of the degradable microorganism nutrition slow-release microspheres and the microorganisms to support the microorganisms to decompose the high ammonia nitrogen wastewater.
Until day 30, from the final water treatment result, the COD and ammonia nitrogen contents in the water after reverse osmosis have obvious expansion compared with the previous 25 days, which indicates that after 30 days of decomposition, the carbon source decomposed by the microorganism nutrition slow-release microspheres can be degraded, the growth requirement of the microorganism can not be met, and the carbon source addition needs to be carried out on the sewage.
In conclusion, the degradable microorganism nutrient slow-release microspheres can decompose nutrient components suitable for microorganism growth under the degradation action of microorganisms, provide carbon sources and phosphorus sources for the growth of the microorganisms, and have good use effect in high ammonia nitrogen sewage treatment. Meanwhile, in the sewage treatment process, the strain nutrition compound agent suitable for the high ammonia nitrogen wastewater is compounded by the liquid nutritional agent which takes effect quickly but has a high decomposition speed and the degradable microbial nutrition slow-release microspheres which take effect slowly but have a long duration, so that the nutrition requirement of microorganisms can be guaranteed continuously in the whole process of sewage treatment, and meanwhile, the degradable microbial nutrition slow-release microspheres can be added once to meet the use duration of about 25 days, so that the labor intensity of operators is greatly reduced, and the labor cost is effectively saved.

Claims (9)

1. The degradable microorganism nutrition slow-release microsphere is characterized by comprising the following components in parts by weight: 30-50 parts of polylactic acid, 20-40 parts of polyhydroxyalkanoate, 15-30 parts of modified starch granules, 5-15 parts of ammonium polyphosphate and 0.5-2 parts of ammonium molybdate;
wherein: the modified starch granules are internally silane-coupled modified starch granules, and a layer of polydopamine is wrapped outside the starch granules;
the preparation method of the modified starch granules comprises the following steps:
(1) Adding tetraethoxysilane and trimethyl borate into an ethanol aqueous solution, and mixing and hydrolyzing to obtain silane hydrolysate;
(2) Then uniformly spraying silane hydrolysate into the starch, drying and curing after uniformly mixing to obtain silane coupling modified starch particles;
(3) And then spraying dopamine aqueous solution on the surface of the silane coupling modified starch particles, and drying in the air atmosphere to obtain the modified starch particles.
2. The degradable microbial nutrition slow release microsphere of claim 1, wherein the mass ratio of tetraethoxysilane, trimethyl borate, ethanol and water in the step (1) is 10: (0.1 to 1): (20 to 30): (20 to 30), the hydrolysis temperature is 60 to 75 ℃, and the hydrolysis reaction time is 3 to 8h.
3. The degradable microbial nutrition sustained-release microspheres of claim 1, wherein the mass ratio of the starch to the silane hydrolysate in the step (2) is 100: (10 to 20) and the curing temperature is 85 to 105 ℃.
4. The degradable microbial nutrition sustained-release microspheres of claim 1, wherein the mass ratio of the silane-coupled modified starch particles to the dopamine aqueous solution in the step (3) is 100: (10 to 20), wherein the concentration of the dopamine aqueous solution is (0.5 to 2) mg/ml, and the drying temperature is 55 to 70 ℃.
5. A preparation method of the degradable microbial nutrition slow release microspheres as claimed in any one of claims 1 to 4, which is characterized by comprising the following steps:
(S.1) uniformly mixing polylactic acid, polyhydroxyalkanoate, modified starch particles, ammonium polyphosphate and ammonium molybdate to obtain a mixed material;
(S.2) extruding and granulating the mixture to obtain granules;
and (S.3) placing the granulated material in a high-pressure kettle, introducing supercritical carbon dioxide into the high-pressure kettle to saturate the granulated material, then decompressing, foaming, cooling and shaping to obtain the degradable microbial nutrition slow-release microspheres.
6. The preparation method of the degradable microbial nutrition slow release microspheres according to claim 5, wherein the extrusion temperature in the step (S.2) is 160-175 ℃.
7. The preparation method of the degradable microbial nutrition slow release microspheres according to claim 5, wherein in the step (S.3), the pressure in an autoclave is 10 to 15MPa, the supercritical treatment temperature is 120 to 145 ℃, the supercritical treatment time is 20 to 60min, the temperature is reduced to 80 to 100 ℃ after the supercritical treatment is finished, the pressure is released, and the microspheres are cooled in an ice water bath.
8. A bacterial nutrition compound agent suitable for high ammonia nitrogen wastewater is characterized by comprising a liquid nutritional agent and degradable microbial nutrition slow release microspheres prepared according to any one of claims 5 to 7.
9. The strain nutrient compound agent suitable for high ammonia nitrogen wastewater as claimed in claim 8, wherein the liquid nutrient agent comprises, by mass: 30 to 40 parts of wheat bran, 20 to 30 parts of vinasse, 3 to 8 parts of sugar residues, 12 to 18 parts of starch, 3 to 8 parts of yeast extract, 0.5 to 2 parts of dipotassium hydrogen phosphate and 100 parts of water.
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