CN111793657A - Method for promoting conversion of amino acids in organic solid waste in cities and towns into volatile fatty acids - Google Patents
Method for promoting conversion of amino acids in organic solid waste in cities and towns into volatile fatty acids Download PDFInfo
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Abstract
The invention discloses a method for promoting conversion of amino acid in organic solid waste in cities and towns into volatile fatty acid, which uses an anionic surfactant to promote microorganisms to degrade the amino acid and generate the volatile fatty acid, wherein the anionic surfactant changes the surface hydrophobicity and the cell permeability of the microorganisms. The invention not only realizes the anaerobic degradation efficiency of the amino acid, but also improves the selectivity of the amino acid converted into volatile fatty acid, thereby realizing the resource recycling.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and particularly relates to a method for promoting conversion of amino acids in organic solid waste in cities and towns into volatile fatty acids.
Background
The organic solid waste in cities and towns has wide sources, various types and large yield, and common household garbage, kitchen garbage, town sludge and the like are available. Meanwhile, the organic solid waste in cities and towns has high organic matter content, biodegradability and huge potential. The organic solid waste in cities and towns has high protein content, and the protein content in waste such as slaughterhouses, cheese, fishes, potato starch, sludge and the like can reach more than 40 percent, even 50 percent. As is well known, various amino acids are produced after protein hydrolysis, the main focus of protein wastewater degradation is to improve protein hydrolysis, for example, pretreatment methods such as alkaline, ultrasonic, ultraviolet, and heating. However, there are few reports on how to degrade hydrolyzed amino acids efficiently and environmentally.
At present, 20 kinds of amino acids constituting protein are found, and research shows that many amino acids are detected in treated fermentation liquor, which indicates that some amino acids are difficult to be degraded and acidified in the anaerobic digestion treatment process. Such as valine, leucine, isoleucine, tryptophan and methionine, are important in human metabolism and are all hydrophobic amino acids. It is known from experiments that these amino acids have relatively poor degradation properties and low production of Volatile Fatty Acids (VFAs) during anaerobic digestion. These amino acids enter the environment, and cause environmental damage and waste of resources. Therefore, it is a problem that how to effectively improve the biodegradability of these amino acids in the anaerobic process and degrade the amino acids into materials for resource utilization is not negligible.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a method for promoting the conversion of amino acid into volatile fatty acid in organic solid waste in cities and towns, which promotes the conversion of amino acid into volatile fatty acid by changing the surface hydrophobicity and cell membrane permeability of microorganisms, not only realizes the anaerobic degradation efficiency of amino acid, but also improves the selectivity of amino acid conversion into volatile fatty acid, and realizes resource recycling.
In order to achieve the above objects and other objects, the present invention provides a method for promoting the conversion of amino acids into volatile fatty acids in organic solid waste in towns, which uses an anionic surfactant to promote the degradation of amino acids by microorganisms and generate volatile fatty acids, wherein the anionic surfactant changes the surface hydrophobicity and cell permeability of the microorganisms.
In one embodiment, the use of anionic surfactants to promote the process of microbial degradation of amino acids and the formation of volatile fatty acids comprises at least the following steps:
providing a reactor;
adding inorganic salt, trace elements, the amino acid and an anionic surfactant into the reactor to obtain a culture medium system;
pretreating sludge;
adding the pretreated sludge into the culture medium system to perform the process of promoting the microorganisms to degrade amino acids and generate volatile fatty acids.
In one embodiment, the anionic surfactant is sodium dodecylbenzenesulfonate, and the amino acid is any one of valine, leucine, and isoleucine.
In one embodiment, the concentration of the sodium dodecyl benzene sulfonate is 5-10 mg/L.
In one embodiment, the anionic surfactant is rhamnolipid, and the amino acid is any one of valine, leucine, isoleucine, tryptophan, and methionine.
In one embodiment, the concentration of the rhamnolipid is 25-50 mg/L.
In one embodiment, the inorganic salt comprises 1.0-1.5 g/L potassium dihydrogen phosphate, 1.0-1.5 g/L ammonium chloride, 0.1-0.5 g/L calcium chloride and 0.1-0.5 g/L magnesium chloride hexahydrate. Specifically, in one embodiment, the inorganic salt has a composition of, for example, 1.0g/L potassium dihydrogen phosphate, 1.0g/L ammonium chloride, 0.1g/L calcium chloride, and 0.1g/L magnesium chloride hexahydrate.
In one embodiment, the trace elements comprise 1.0-1.5 mg/L ferric chloride, 0.5-1.0 mg/L zinc sulfate heptahydrate, 0.5-1.0 mg/L cobalt chloride hexahydrate, 1.0-1.5 mg/L nickel chloride hexahydrate, 0.5-1.0 mg/L copper sulfate pentahydrate, and 0.5-1.0 mg/L manganese chloride tetrahydrate. Specifically, in one embodiment, the trace elements may be, for example, 1.0mg/L ferric chloride, 0.5mg/L zinc sulfate heptahydrate, 0.5mg/L cobalt chloride hexahydrate, 1.0mg/L nickel chloride hexahydrate, 0.5mg/L copper sulfate pentahydrate, and 0.5mg/L manganese chloride tetrahydrate.
In one embodiment, the pH during the process of promoting the conversion of an amino acid to a volatile fatty acid is 7.0 ± 0.2.
In one embodiment, the reactor is an anaerobic serum bottle.
In one embodiment, the microorganisms are microorganisms in sludge.
In one embodiment, the initial TSS of the sludge is 1.0-1.1 g/L.
In one embodiment, the reaction temperature in the process of promoting the microorganisms to degrade the amino acids and generate the volatile fatty acids is 35 ± 2 ℃, and the reaction time is, for example, 7 to 8 days.
In the present invention, the conversion of amino acids into volatile fatty acids is promoted by changing the surface hydrophobicity and cell membrane permeability of microorganisms using an anionic surfactant, such as rhamnolipid or sodium dodecylbenzenesulfonate. The invention leads the amino acid, the anionic surfactant and the microorganism to generate the synergistic effect, promotes the degradation of the amino acid, simultaneously realizes the improvement of the yield of Volatile Fatty Acids (VFAs), realizes the resource recycling, and has environmental protection and no pollution in the whole process. The invention not only saves cost, but also has less harmful intermediate products and less secondary pollution, and the final product can also be directly recycled.
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Fig. 1 is a schematic flow chart of a method according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. It is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.
When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs and the description of the present invention, and any methods, apparatuses, and materials similar or equivalent to those described in the examples of the present invention may be used to practice the present invention.
It is to be noted that "min" in the present invention means "minute", "rpm" means "rotation per minute", "ml" means "ml", and "μm" means "micron".
The invention provides a method for promoting conversion of amino acid into volatile fatty acid in organic solid waste in cities and towns, which changes the surface hydrophobicity and cell membrane permeability of microorganisms by using an anionic surfactant such as rhamnolipid or sodium dodecyl benzene sulfonate to promote conversion of the amino acid into the volatile fatty acid.
Referring to fig. 1, in one embodiment, the process of using anionic surfactant to promote the degradation of amino acids and the formation of volatile fatty acids by microorganisms includes at least the following steps:
s1, providing a reactor;
s2, adding inorganic salt, trace elements, the amino acid and an anionic surfactant into the reactor to obtain a culture medium system;
s3, pretreating the sludge;
s4, adding the pretreated sludge into the culture medium system to carry out the process of promoting the microorganism to degrade amino acid and generate volatile fatty acid.
Specifically, in step S1, the reactor is, for example, an anaerobic serum bottle. For example, the reactor is placed in a constant temperature shaker at 150rpm for reaction.
Specifically, in step S2, when the anionic surfactant is, for example, sodium dodecylbenzenesulfonate, the amino acid is any one of valine, leucine, and isoleucine. The concentration of the sodium dodecyl benzene sulfonate is 5-10 mg/L. In another embodiment, when the anionic surfactant is, for example, rhamnolipid, the amino acid is any one of valine, leucine, isoleucine, tryptophan and methionine. The concentration of the rhamnolipid is 25-50 mg/L. Since the amino acids have different structures and thus different properties, the amino acids to which sodium dodecylbenzenesulfonate and rhamnolipid are directed in the present invention are different in kind. Selecting one of said amino acids as the sole carbon source in said reactor. The inorganic salt is composed of, for example, 1.0 to 1.5g/L potassium dihydrogen phosphate, 1.0 to 1.5g/L ammonium chloride, 0.1 to 0.5g/L calcium chloride, and 0.1 to 0.5g/L magnesium chloride hexahydrate. Specifically, in one embodiment, the inorganic salt has a composition of, for example, 1.0g/L potassium dihydrogen phosphate, 1.0g/L ammonium chloride, 0.1g/L calcium chloride, and 0.1g/L magnesium chloride hexahydrate. In one embodiment, the trace elements comprise 1.0-1.5 mg/L ferric chloride, 0.5-1.0 mg/L zinc sulfate heptahydrate, 0.5-1.0 mg/L cobalt chloride hexahydrate, 1.0-1.5 mg/L nickel chloride hexahydrate, 0.5-1.0 mg/L copper sulfate pentahydrate, and 0.5-1.0 mg/L manganese chloride tetrahydrate. Specifically, in one embodiment, the trace elements may be, for example, 1.0mg/L ferric chloride, 0.5mg/L zinc sulfate heptahydrate, 0.5mg/L cobalt chloride hexahydrate, 1.0mg/L nickel chloride hexahydrate, 0.5mg/L copper sulfate pentahydrate, and 0.5mg/L manganese chloride tetrahydrate. The concentration of the amino acid is, for example, 1.5 to 2.0g/L
Specifically, in step S3, the initial TSS of the sludge is 1.0-1.1 g/L. The specific process of pretreating the sludge comprises the steps of standing the sludge taken from a secondary sedimentation tank of a sewage treatment plant for 24 hours, removing supernatant, removing large particles by sieving, centrifuging the concentrated sludge, removing the supernatant, adding tap water with the same volume, mixing uniformly, centrifuging again, washing for 3 times by using tap water, removing organic matters in the sludge, adding tap water with the same volume to resuspend the sludge, and obtaining the pretreated sludge for anaerobic conversion of amino acids into Volatile Fatty Acids (VFAs).
Specifically, in step S4, the pH during the process of promoting the microbial degradation of amino acids and generating volatile fatty acids is, for example, 7.0 ± 0.2, the reaction temperature is, for example, 35 ± 2 ℃, and the reaction time is, for example, 7 to 8 days. Under anaerobic conditions, the temperature and pH in the process of degrading amino acid are critical to the anaerobic degradation of amino acid, and can have important influence on the activity of microorganisms. In addition, a control group without the addition of the anionic surfactant was provided to compare the effects of, for example, the addition of the anionic surfactant and the absence of the addition of the anionic surfactant.
The concentration of the amino acid is detected by high performance liquid chromatography, and the specific detection process and conditions are as follows: after 1.5mL of the sample was centrifuged at 4500rpm for 5 minutes, the supernatant was removed and passed through a 0.22 μm aqueous filter, and the filtered liquid was subjected to HPLC analysis. The instrument adopts an Agilent 1200 series high performance liquid chromatograph, a chromatographic column: durashell AA column, 3 μm, 4.6X 150 mm. Column temperature: at 45 ℃. Detection wavelength: 338nm (VWD detector). Mobile phase A disodium hydrogen phosphate dodecahydrate (Na)2HPO4·12H2O)9.0g, sodium tetraborate decahydrate (Na)2B4O7·10H2O)9.5g, 2000mL of water was added, the pH was adjusted to 8.2 with hydrochloric acid, and the mixture was filtered through a 0.45 μm filter. Mobile phase B: 450mL of methanol, 450mL of acetonitrile and 100mL of water are mixed uniformly and degassed by ultrasound.
The content and the composition of Volatile Fatty Acids (VFAs) are detected by gas chromatography, and the specific detection process and conditions are as follows: the VFA was measured using an Agilent model 7820 gas chromatograph, which was a hydrogen Flame Ionization Detector (FID). The parameters of the gas chromatograph are set as follows: the chromatographic column is DB-WAXETR capillary chromatographic column, and has a length of 30m, an inner diameter of 530 μm, and a film thickness of 1.0 μm; the hydrogen flow is 40mL/min, the air flow is 400mL/min, and the carrier gas nitrogen flow is 25 mL/min; an automatic sample injector is used for injecting samples from a sample injection port, and the sample injection amount is 0.5 mu L. The six VFAs were peaked sequentially with acetic acid (about 6.55 minutes), propionic acid (about 7.51 minutes), isobutyric acid (about 7.83 minutes), n-butyric acid (about 8.50 minutes), isovaleric acid (about 8.95 minutes), and n-valeric acid (about 9.69 minutes).
In some embodiments, when the anionic surfactant is sodium dodecylbenzenesulfonate, such as any one of valine, leucine, and isoleucine, the degradation rate of the amino acid and the yield of volatile fatty acid are exemplified below.
As shown in table 1, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then valine with the concentration of 1.5g/L and SDBS with the concentration of 5mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃, reacting for 8 days, and carrying out an experiment of anaerobic conversion of valine into VFAs, which is recorded as a system D. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace element composition comprises: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the completion of the reaction, the degradation rate of valine was 67.6% and the yield of VFAs was 1666.2mgCOD/L, which was 29.3% higher than that of comparative System A.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of the treated sludge, inorganic salts and trace elements were added to a 600mL serum bottle, followed by 1.5g/L valine and 7.5mg/L valineSDBS, adding tap water to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of valine into VFAs, which is recorded as a system E. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace element composition comprises: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the completion of the reaction, the degradation rate of valine was 75.2% and the yield of VFAs was 1927.6mgCOD/L, which was 49.6% higher than that of comparative System A.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then valine with the concentration of 1.5g/L and SDBS with the concentration of 10mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of converting valine into VFAs through anaerobic reduction, wherein the experiment is recorded as a system F. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace element composition comprises: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. As a result, it was found that the degradation rate of valine was 78.7% and the yield of VFAs was 1902.5mgCOD/L after the completion of the reaction, as compared with the controlThe improvement of line A is 47.7%.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, leucine with the concentration of 1.5g/L is added, 5mg/L of SDBS is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, carrying out an experiment of anaerobic conversion of leucine into VFAs, and recording the experiment as a system G. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the leucine degradation rate was 60.7% and the VFAs yield was 1407.5mgCOD/L, which was 38.6% higher than that of comparative system B.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, leucine with the concentration of 1.5g/L is added, 7.5mg/L of SDBS is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of leucine into VFAs, which is recorded as a system H. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the leucine degradation rate was 68.8% and the VFAs yield was 1681.7mgCOD/L, which was 65.6% higher than that of comparative system B.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, leucine with the concentration of 1.5g/L is added, 10mg/L of SDBS is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of leucine into VFAs, which is recorded as a system I. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the leucine degradation rate was 67.2% and the VFAs yield was 1597.9mgCOD/L, which was 57.4% higher than that of comparative system B.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). Adding 15mL of treated sludge, inorganic salt and trace elements into a 600mL serum bottle, adding 1.5g/L isoleucine, and adding5mg/L SDBS, adding tap water to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of isoleucine into VFAs, which is recorded as a system J. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the isoleucine degradation rate was 52.5% and the yield of VFAs was 1319.0mgCOD/L, which was 19.6% higher than that of comparative system C.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then isoleucine with the concentration of 1.5g/L is added, 7.5mg/L of SDBS is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of isoleucine into VFAs, which is recorded as a system K. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the completion of the reaction, the degradation rate of isoleucine was 55.6%, the yield of VFAs was 1515.8mgCOD/L,compared with the comparative system C, the improvement is 37.5 percent.
In another example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then isoleucine with the concentration of 1.5g/L is added, 10mg/L of SDBS is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of isoleucine into VFAs, which is recorded as a system L. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the isoleucine degradation rate was 65.2% and the yield of VFAs was 1518.2mgCOD/L, which was 37.7% higher than that of comparative system C.
Referring to table 1, in a comparative example, sludge from a secondary sedimentation tank of a sewage treatment plant is left to stand for 24 hours, supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS (pH) of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). Adding 15mL of treated sludge, inorganic salt and trace elements into a 600mL serum bottle, adding valine with the concentration of 1.5g/L, adding tap water to supplement to 300mL of effective volume, adjusting the pH of a reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing by using a rubber plug, placing in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, carrying out an experiment for anaerobic conversion of the valine into VFAs, and recording as a comparison system A. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/LNH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/LZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/LMnCl4·4H2And O. As a result, the degradation rate of valine was 54.8% and the yield of VFAs was 1288.4mgCOD/L after the completion of the reaction, which was used as a control.
In another comparative example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then leucine with the concentration of 1.5g/L is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, carrying out an experiment of converting leucine into VFAs in an anaerobic manner, and recording the experiment as a comparison system B. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/LNH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/LZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/LMnCl4·4H2And O. As a result, the leucine degradation rate was 42.2% and the VFAs yield was 1015.3mgCOD/L after the completion of the reaction, and this was used as a control.
In another comparative example, as shown in table 1, the sludge from the secondary sedimentation tank of the sewage treatment plant was left to stand for 24 hours, the supernatant was removed, the supernatant was concentrated and sieved to remove large particles, and then the TSS of the sludge was measured at 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then isoleucine with the concentration of 1.5g/L is added, and tap water is added to make up to 300mL of effective volume. Adjustment with NaOH and HClThe pH of the reaction system is 7.0, nitrogen is blown for 2 minutes, the rubber plug is sealed, the reaction system is placed in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and the experiment of anaerobic conversion of isoleucine into VFAs is carried out, and the reaction system is recorded as a comparative system C. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. As a result, the degradation rate of isoleucine was 33.4% and the yield of VFAs was 1102.3mgCOD/L after completion of the reaction, which was used as a control.
TABLE 1 data comparison Table of some examples of the invention
Since the anaerobic degradation efficiency of the amino acids (e.g., valine, leucine, and isoleucine) at the same concentration is lower than that of other amino acids (glutamic acid, glutamine, aspartic acid, asparagine, serine, etc.). As is apparent from the analysis of the data in Table 1 and the examples, the addition of, for example, Sodium Dodecylbenzenesulfonate (SDBS) improves the efficiency of anaerobic degradation of amino acids and the yield of Volatile Fatty Acids (VFAs) with different amino acids (valine, leucine and isoleucine) as the sole carbon source in anaerobic fermentation, for example, at a concentration of 1.5 g/L. For example, Sodium Dodecyl Benzene Sulfonate (SDBS) is added into an amino acid anaerobic fermentation system, the surface hydrophobicity and cell membrane permeability of microorganisms are changed through the combined action of the Sodium Dodecyl Benzene Sulfonate (SDBS) on amino acid and the Sodium Dodecyl Benzene Sulfonate (SDBS) on anaerobic microorganisms, the degradation efficiency of the amino acid is increased, and meanwhile, the yield of Volatile Fatty Acids (VFAs) in the acidification process is also improved. In order to prevent the inhibition of microbial activity and the damage to the environment caused by insufficient degradation of, for example, Sodium Dodecylbenzenesulfonate (SDBS), the concentration of the SDBS of the present invention is selected to be, for example, 5 to 10 mg/L. Specifically, under the condition of selecting low-concentration SDBS, the degradation effect of SDBS on different amino acids is different, and the degradation of the amino acids is also influenced by the concentration of SDBS. For example, SDBS at a concentration of 5mg/L has a lower effect on enhancing the anaerobic degradation of amino acids than SDBS at higher concentrations (7.5mg/L and 10 mg/L). It can be seen that there is no significant difference between the addition of 7.5mg/L and 10mg/L SDBS in improving the anaerobic degradation of valine, leucine and isoleucine, and that higher concentrations of SDBS can be biologically toxic to microorganisms and can cause environmental hazards, so that higher concentrations of SDBS are not required.
In other embodiments, when the anionic surfactant is, for example, rhamnolipid, the amino acid is any one of valine, leucine, isoleucine, tryptophan and methionine, and the degradation rate of the amino acid and the yield of volatile fatty acid are exemplified below.
As shown in table 2, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then valine with the concentration of 1.5g/L and rhamnolipid with the concentration of 25mg/L are added, and tap water is added to make up to the effective volume of 300 mL. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of valine into VFAs, wherein the experiment is recorded as a system F1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the completion of the reaction, the degradation rate of valine was 71.9%, and the yield of VFAs was 1739.4mgCOD/L, which was increased by 35.0% as compared with comparative System A.
As shown in table 2, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then valine with the concentration of 1.5g/L and rhamnolipid with the concentration of 50mg/L are added, and tap water is added to make up to the effective volume of 300 mL. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of valine into VFAs, wherein the experiment is recorded as a system G1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the completion of the reaction, the degradation rate of valine was 80.8% and the yield of VFAs was 1978.7mgCOD/L, which was 53.6% higher than that of comparative System A.
In another example, as shown in table 2, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then leucine with the concentration of 1.5g/L is added, rhamnolipid with the concentration of 25mg/L is added, and tap water is added to make up to 300mL of effective volume. Adjusting pH of the reaction system to 7.0 with NaOH and HCl, blowing nitrogen for 2 minutes, sealing with rubber plug, placing in a constant temperature shaking table at 35 + -2 deg.C for 8 days, and anaerobically converting leucine into VFAsThe test was written as system H1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction was complete, the leucine degradation rate was 60.1% and the VFAs yield was 1422.4mgCOD/L, which was 40.1% higher than that of comparative System B.
In another example, as shown in table 2, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20-22 g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then leucine with the concentration of 1.5g/L is added, rhamnolipid with the concentration of 50mg/L is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of leucine into VFAs, wherein the experiment is recorded as a system I1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the leucine degradation rate was 73.6% and the VFAs yield was 1761.1mgCOD/L, which was 73.4% higher than that of comparative system B.
Referring to Table 2, in another embodiment, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the sludge is concentrated and sieved, and the large particles are removedSludge TSS 20-22 g/L (pH 6.8 + -0.2) was measured. 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then isoleucine with the concentration of 1.5g/L is added, 25mg/L of rhamnolipid is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of isoleucine into VFAs, which is recorded as a system J1. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the isoleucine degradation rate was 47.0% and the yield of VFAs was 1248.9mgCOD/L, which was 13.3% higher than that of comparative system C.
In another example, as shown in table 2, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then isoleucine with the concentration of 1.5g/L is added, 50mg/L of rhamnolipid is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by NaOH and HCl, blowing nitrogen for 2 minutes, sealing by a rubber plug, placing in a constant temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of isoleucine into VFAs, which is recorded as a system K1. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the isoleucine degradation rate was 74.3% and the yield of VFAs was 2038.3mgCOD/L, which was 84.9% higher than that of comparative system C.
As shown in table 2, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then methionine with the concentration of 1.5g/L and rhamnolipid with the concentration of 25mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of methionine into VFAs, wherein the experiment is recorded as a system L1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the degradation rate of methionine was 37.4%, the yield of VFAs was 432.7mgCOD/L, which was 40.1% higher than that of comparative system D1.
As shown in table 2, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then methionine with the concentration of 1.5g/L and rhamnolipid with the concentration of 50mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting pH of the reaction system to 7.0 with NaOH and HCl, blowing nitrogen for 2 minutes, sealing with rubber plug, placing in 35 + -2 deg.C constant temperature shaking table for 8 days, and laying eggsAn experiment for the anaerobic conversion of amino acids to VFAs is described as system M1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the degradation rate of methionine was 73.9%, the yield of VFAs was 750.4mgCOD/L, which was increased by 143.0% compared to comparative system D1.
As shown in table 2, in one example, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, the supernatant is concentrated and sieved, large particles are removed, and then the TSS of the sludge is measured to be 20 to 22g/L (pH is 6.8 ± 0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then tryptophan with the concentration of 1.5g/L and rhamnolipid with the concentration of 25mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of tryptophan into VFAs, wherein the experiment is recorded as a system N1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the degradation rate of tryptophan was 46.7%, and the yield of VFAs was 350.2mgCOD/L, which was 48.3% higher than that of comparative system E1.
Referring to Table 2, in one embodiment, the sludge from the secondary sedimentation tank of the sewage treatment plant is left to stand for 24 hours, the supernatant is removed, and the sludge is concentrated, sieved and removedAfter the particles are agglomerated, the TSS of the sludge is measured at 20-22 g/L (pH 6.8 + -0.2). 15mL of treated sludge, inorganic salts and trace elements are added into a 600mL serum bottle, then tryptophan with the concentration of 1.5g/L and rhamnolipid with the concentration of 50mg/L are added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, and carrying out an experiment of anaerobic conversion of tryptophan into VFAs, wherein the experiment is recorded as a system O1. The composition of the inorganic salt in the reactor is 1.0g/LKH2PO3，1.0g/L NH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/LFeCl3，0.5mg/L ZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/LCuSO4·5H2O，0.5mg/L MnCl4·4H2And O. The results showed that after the reaction, the tryptophan degradation rate was 66.7%, the yield of VFAs was 500.7mgCOD/L, which was 112.0% higher than that of comparative system E1.
Referring to table 2, in a comparative example, the sludge from the secondary sedimentation tank of the sewage treatment plant was left to stand for 24 hours, the supernatant was removed, the supernatant was concentrated, the filtrate was sieved to remove large particles, and then the TSS of the sludge was measured at 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then methionine with the concentration of 1.5g/L is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, carrying out an experiment of converting methionine into VFAs in an anaerobic manner, and recording the experiment as a comparison system D1. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/LNH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/LZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/LMnCl4·4H2And O. As a result, the degradation rate of methionine after the completion of the reaction was 26.4%, and the yield of VFAs was 308.8mgCOD/L, which was used as a control group.
Referring to table 2, in a comparative example, the sludge from the secondary sedimentation tank of the sewage treatment plant was left to stand for 24 hours, the supernatant was removed, the supernatant was concentrated, the filtrate was sieved to remove large particles, and then the TSS of the sludge was measured at 20 to 22g/L (pH 6.8 ± 0.2). 15mL of treated sludge, inorganic salt and trace elements are added into a 600mL serum bottle, then tryptophan with the concentration of 1.5g/L is added, and tap water is added to make up to 300mL of effective volume. Adjusting the pH value of the reaction system to 7.0 by using NaOH and HCl, blowing nitrogen for 2 minutes, sealing a rubber plug, placing the rubber plug in a constant-temperature shaking table at 35 +/-2 ℃ for 8 days, carrying out an experiment of anaerobic conversion of tryptophan into VFAs, and recording the experiment as a comparison system E1. The composition of the inorganic salt in the reactor is 1.0g/L KH2PO3，1.0g/LNH4Cl，0.1g/L CaCl2，0.1g/L MgCl2·6H2And O. The trace elements comprise: 1.0mg/L FeCl3，0.5mg/LZnSO4·7H2O，0.5mg/L CoCl2·6H2O，1.0mg/L NiCl2·6H2O，0.5mg/L CuSO4·5H2O，0.5mg/LMnCl4·4H2And O. As a result, the degradation rate of tryptophan after the completion of the reaction was 29.9%, and the yield of VFAs was 236.2mgCOD/L, which was used as a control.
TABLE 2 comparison of data from some examples of the invention
The present invention can change the surface characteristics of the microorganism, such as surface hydrophobicity and cell membrane permeability, by adding rhamnolipid, thereby improving the bioavailability of the substrate by the microorganism. According to the data analysis in Table 2 and the examples, it was found that different hydrophobic amino acids (valine, leucine, isoleucine, methionine and tryptophan) were used as the sole carbon source in anaerobic fermentation at concentrations of, for example, 1.5 g/L. The addition of rhamnolipids can increase the anaerobic degradation of hydrophobic amino acids and the production of VFAs. The rhamnolipid has different effects on the degradation of different amino acids, and the degradation of the amino acids is also influenced by the concentration of the rhamnolipid. As can be seen from Table 2, in the exemplified examples, the degradation of amino acids was the best when 50mg/L of rhamnolipid was added.
In view of the above, in the present invention, the conversion of amino acids into volatile fatty acids is promoted by changing the surface hydrophobicity and cell membrane permeability of microorganisms using an anionic surfactant, such as rhamnolipid or sodium dodecylbenzenesulfonate. The invention leads the amino acid, the anionic surfactant and the microorganism to generate the synergistic effect, promotes the degradation of the amino acid, simultaneously realizes the improvement of the yield of Volatile Fatty Acids (VFAs), realizes the resource recycling, and has environmental protection and no pollution in the whole process. The invention not only saves cost, but also has less harmful intermediate products and less secondary pollution, and the final product can also be directly recycled.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it should also be understood that unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention which may be practiced, nor is it intended to limit the relative changes or modifications to the scope of the invention which may be practiced without materially changing the technical details.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A method for promoting the conversion of amino acids into volatile fatty acids in organic solid waste in cities and towns is characterized in that an anionic surfactant is used for promoting the degradation of the amino acids by microorganisms and the generation of the volatile fatty acids, and the surface hydrophobicity and the cell permeability of the microorganisms are changed by the anionic surfactant.
2. The method according to claim 1, wherein the use of anionic surfactants to promote the process of microbial degradation of amino acids and the formation of volatile fatty acids comprises at least the following steps:
providing a reactor;
adding inorganic salt, trace elements, the amino acid and an anionic surfactant into the reactor to obtain a culture medium system;
pretreating sludge;
adding the pretreated sludge into the culture medium system to perform the process of promoting the microorganisms to degrade amino acids and generate volatile fatty acids.
3. The method according to claim 1, wherein the anionic surfactant is sodium dodecylbenzenesulfonate, and the amino acid is any one of valine, leucine and isoleucine.
4. The method according to claim 3, wherein the concentration of the sodium dodecylbenzenesulfonate is 5 to 10 mg/L.
5. The method according to claim 1, wherein the anionic surfactant is rhamnolipid and the amino acid is any one of valine, leucine, isoleucine, tryptophan and methionine.
6. The method according to claim 5, wherein the concentration of the rhamnolipid is 25-50 mg/L.
7. The method according to claim 2, wherein the composition of the inorganic salt comprises 1.0-1.5 g/L potassium dihydrogen phosphate, 1.0-1.5 g/L ammonium chloride, 0.1-0.5 g/L calcium chloride and 0.1-0.5 g/L magnesium chloride hexahydrate.
8. The method for promoting microbial degradation of amino acids and generation of volatile fatty acids as claimed in claim 2, wherein the composition of the trace elements comprises 1.0-1.5 mg/L ferric chloride, 0.5-1.0 mg/L zinc sulfate heptahydrate, 0.5-1.0 mg/L cobalt chloride hexahydrate, 1.0-1.5 mg/L nickel chloride hexahydrate, 0.5-1.0 mg/L copper sulfate pentahydrate, and 0.5-1.0 mg/L manganese chloride tetrahydrate.
9. The method of claim 2, wherein the pH during the process of promoting microbial degradation of amino acids and production of volatile fatty acids is 7.0 ± 0.2.
10. The method of claim 2, wherein the reactor is an anaerobic serum bottle.
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