CN114921503B - Method for synthesizing polyhydroxyalkanoate and application thereof - Google Patents
Method for synthesizing polyhydroxyalkanoate and application thereof Download PDFInfo
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- CN114921503B CN114921503B CN202210713557.4A CN202210713557A CN114921503B CN 114921503 B CN114921503 B CN 114921503B CN 202210713557 A CN202210713557 A CN 202210713557A CN 114921503 B CN114921503 B CN 114921503B
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- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P7/00—Preparation of oxygen-containing organic compounds
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- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12R—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES C12C - C12Q, RELATING TO MICROORGANISMS
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention provides a method for synthesizing polyhydroxyalkanoate and application thereof, belonging to the technical field of environmental protection. The invention takes kitchen waste anaerobic hydrolysis acidification liquid as a carbon source and rhodopseudomonas palustris as a functional microorganism, and synthesizes the product polyhydroxyalkanoate through constant temperature culture. According to the invention, rhodopseudomonas palustris is used as a functional microorganism for synthesizing the polyhydroxyalkanoate by utilizing the kitchen waste for the first time, so that the synthesis efficiency of the polyhydroxyalkanoate is effectively improved, and the yield of volatile fatty acid in anaerobic hydrolytic acidification of the kitchen waste is improved by means of ultrasonic-alkali combination and addition of exogenous substances, so that the synthesis efficiency of the polyhydroxyalkanoate is greatly improved.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and particularly relates to a method for synthesizing polyhydroxyalkanoate and application thereof.
Background
Polyhydroxyalkanoate (PHA) is a recognized green and environment-friendly polymer material, has the advantages of thermoplasticity, biodegradability, biosolubility, regenerability and the like, can be used as a substitute for refractory plastics, and is applied to the fields of biomedical equipment, electronics, buildings, automobiles, packaging and agriculture. Common PHA monomers are poly-3-hydroxybutyrate (PHB) and poly-hydroxyvalerate (PHV). In recent years, PHAs are mainly produced by using edible vegetable oil, grains and other crops, and directly compete with grain supply production. Therefore, other raw materials are used as a carbon source for producing PHA, and extensive researches on domestic and foreign scholars are obtained.
Kitchen waste is the most main food residue in food waste, and comprises edible residues generated in families, schools, canteens, catering industries and the like, and the kitchen waste has complex components and is a mixture of various substances such as oil, water, pericarp, vegetables, rice and flour, fish, meat, bones, waste tableware, plastics, tissues and the like. The kitchen waste has high organic matter content, and Volatile Fatty Acids (VFAs) generated by anaerobic hydrolysis acidification can be used as a carbon source for synthesizing PHA by microorganisms, and has the following advantages: (1) The kitchen waste has huge yield and contains a large amount of organic matters; (2) Anaerobic digestion is a well-known resource type harmless treatment method; (3) VFAs are important intermediates produced in the acidification step when organics are treated by anaerobic digestion and have wide industrial application. However, in the technology of synthesizing PHA by using kitchen waste as a carbon source and utilizing microorganisms, the PHA synthesis rate is generally not high, so that it is necessary to develop a method with high PHA synthesis rate to synthesize PHA so as to realize the recycling treatment of waste and the production of sustainable development products.
Disclosure of Invention
Accordingly, the invention aims to provide a method for synthesizing polyhydroxyalkanoate, which can effectively improve the synthesis rate of polyhydroxyalkanoate and recycle kitchen waste.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for synthesizing polyhydroxyalkanoate, which comprises the following steps: inoculating rhodopseudomonas palustris into the anaerobic hydrolysis acidification liquid of the kitchen waste for culturing, and extracting polyhydroxyalkanoate in the rhodopseudomonas palustris after the culturing is finished.
Preferably, the preparation method of the anaerobic hydrolysis acidification liquid for kitchen waste comprises the following steps: and (3) carrying out anaerobic hydrolysis acidification after pretreatment of the kitchen waste, centrifuging hydrolysis acidification products, and reserving supernatant.
Preferably, the pretreatment method comprises the following steps: and crushing kitchen waste, and then carrying out ultrasonic-alkali combined pretreatment.
Preferably, the conditions of the ultrasonic-alkali combined pretreatment are as follows: ultrasonic treatment for 8-12 min with pH value of 8.5-9.5.
Preferably, the mass ratio of the kitchen waste to the inoculated sludge is 1.5-2.5: 1, mixing and then carrying out anaerobic hydrolytic acidification, wherein the anaerobic conditions are as follows: the pH value is 8.5-9.5, the anaerobic temperature is 33-36 ℃ and the time is 6-8 d.
Preferably, one or more of magnetite, anthraquinone-2-sulfonic acid and alkyl glycoside are added into the anaerobic hydrolysis acidification system.
Preferably, the anaerobic hydrolysis acidification liquid of the kitchen waste eliminates mixed bacteria, is diluted to the concentration of 2000-2400 mg/L, and is inoculated with rhodopseudomonas palustris.
Preferably, the rhodopseudomonas palustris has an inoculum size of 13-16%.
Preferably, the culture conditions are: the illumination intensity is 1800-2200 lux, the rotating speed is 160-200 rpm, the reaction temperature is 28-32 ℃, the initial pH value is 7.8-8.2, and the culture time is 28-32 d.
The invention also provides application of the method in kitchen waste treatment or polyhydroxyalkanoate industrial production.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the anaerobic hydrolysis acidification liquid of the kitchen waste is used as a carbon source, and rhodopseudomonas palustris is used as a functional microorganism to synthesize polyhydroxyalkanoate, so that the kitchen waste can be recycled, the VFAs in the anaerobic hydrolysis acidification liquid of the kitchen waste are effectively utilized to synthesize PHA, and the method has higher PHA synthesis efficiency.
According to the invention, the kitchen waste is pretreated, so that the yield of volatile fatty acid in the anaerobic hydrolysis acidification liquid of the kitchen waste can be increased, and the synthesis efficiency of the polyhydroxyalkanoate is improved.
According to the invention, the exogenous substances are added into the anaerobic hydrolysis acidification system of the kitchen waste, so that the yield of volatile fatty acid in the anaerobic hydrolysis acidification liquid of the kitchen waste is further improved, and the synthesis efficiency of the polyhydroxyalkanoate is further improved.
Drawings
Fig. 1: gas chromatography standard curves of PHB and PHV;
fig. 2: VFAs change rules under different ultrasonic-alkali pretreatment conditions;
fig. 3: the effect of different ultrasonic-alkali pretreatment conditions on acetic acid;
fig. 4: influence of different ultrasonic-alkali pretreatment conditions on butyric acid;
fig. 5: SEM images of kitchen waste under different ultrasonic-alkali pretreatment conditions;
fig. 6: methanogenic bacteria morphology;
fig. 7: different Fe 3 O 4 The generation rule of the VFAs under the condition of the addition quantity;
fig. 8: different Fe 3 O 4 The VFAs components are distributed under the condition of the adding amount;
fig. 9: the generation rule of the VFAs under different AQS addition amount conditions;
fig. 10: VFAs components are distributed under different AQS addition amount conditions;
fig. 11: the generation rule of the VFAs under the condition of different APG06 addition amounts;
fig. 12: VFAs components are distributed under different APG06 addition amount conditions;
fig. 13: influence of rhodopseudomonas palustris culture time on PHA synthesis rate;
fig. 14: influence of substrate concentration on PHA synthesis by rhodopseudomonas palustris;
fig. 15: influence of pH on PHA synthesis by rhodopseudomonas palustris;
fig. 16: influence of rhodopseudomonas palustris inoculum size on PHA synthesis;
fig. 17: effects of the composition of VFAs on PHA synthesis by rhodopseudomonas palustris.
Detailed Description
The invention provides a method for synthesizing polyhydroxyalkanoate, which comprises the following steps: inoculating rhodopseudomonas palustris into the anaerobic hydrolysis acidification liquid of the kitchen waste for culturing, and extracting polyhydroxyalkanoate in the rhodopseudomonas palustris after the culturing is finished. According to the invention, the anaerobic hydrolysis acidification liquid of the kitchen waste is used as a carbon source, rhodopseudomonas palustris is used as a functional microorganism, VFAs in the anaerobic hydrolysis acidification liquid of the kitchen waste are synthesized into PHA through the metabolic activity of rhodopseudomonas palustris, and then polyhydroxyalkanoate in the rhodopseudomonas palustris is extracted to obtain a powdery PHA crude product.
The PHA crude product obtained by the method has the main component of PHB.
The kitchen waste is kitchen waste generated in daily life, and specific sources are not limited.
The preparation method of the anaerobic hydrolysis acidification liquid for kitchen waste comprises the following steps: and (3) carrying out anaerobic hydrolysis acidification after pretreatment of the kitchen waste, centrifuging hydrolysis acidification products, and reserving supernatant.
The method comprises the steps of crushing kitchen waste, adopting a conventional crusher, and then carrying out ultrasonic-alkali combined pretreatment on the crushed kitchen waste.
According to the invention, an alkaline substance, preferably one of calcium hydroxide, potassium hydroxide and sodium hydroxide, is added to the crushed kitchen waste to adjust the pH. The pH value of the kitchen waste is adjusted to 8.5-9.5, preferably 8.8-9.2, more preferably 9 by adding alkaline substances.
The invention can lead the system to contain a large amount of OH by alkali treatment - Destroying acidified substrate cells, hydrolyzing and saponifying macromolecular organic matters, inhibiting methanogenesis, increasing hydrolysis rate, and generating more VFAs in the same time. The pH value is selected to be 8.5-9.5, so that the influence of an extreme alkaline environment on the enzyme activity and the microorganism growth metabolism in the system is avoided, and the VFAs content can be improved to the greatest extent.
The invention carries out ultrasonic treatment on the kitchen waste after alkali treatment for 8-12 min. The ultrasonic treatment time is preferably 9 to 11 minutes, more preferably 10 minutes. As an alternative implementation mode, the kitchen waste is placed in a double frequency air ultrasonic cleaner (KQ-300 VDE) and subjected to ultrasonic treatment for 8-12 min under the condition of 80 kHz.
The invention can destroy the large-particle organic matter structure in the kitchen waste by utilizing ultrasonic pretreatment, thereby being beneficial to the generation of VFAs. Meanwhile, the ultrasonic treatment time is 8-12 min, so that the problem that small and medium particles are agglomerated again into large-particle organic matters in the system and are unfavorable for hydrolysis is avoided.
The invention puts the kitchen waste which is pretreated by ultrasonic-alkali combination into an anaerobic reactor for anaerobic hydrolysis acidification, and the mass ratio of the kitchen waste to the inoculated sludge is 1.5-2.5: 1, preferably 2:1. the anaerobic hydrolysis acidification conditions are as follows: the pH value is 8.5-9.5, preferably 9; the temperature is 33-36 ℃, preferably 35 ℃; time 6 to 8d, preferably time 7d.
According to the invention, the kitchen waste is pretreated by ultrasonic-alkali combination, so that the dissolution of organic matters can be promoted, the hydrolysis rate of the kitchen waste is improved, the methanogenesis process is inhibited, a large amount of VFAs are produced in a system after anaerobic hydrolysis acidification, and the synthesis potential of FHA can be effectively improved.
In the invention, exogenous substances can be further added into the anaerobic hydrolysis acidification system to promote the generation of VFAs. Preferably, the exogenous material comprises one or more of magnetite, anthraquinone-2-sulfonic acid and alkyl glycoside.
Magnetite (Fe) of the present invention 3 O 4 ) The amount of (C) added is preferably 9 to 11g/L, more preferably 10g/L; the addition amount of the anthraquinone-2-sulfonic Acid (AQS) is preferably 110-130 mg/L, more preferably 120mg/L; the amount of the alkyl glycoside (APG 06) to be added is preferably 9 to 10g/L, more preferably 9.45 to 9.6g/L.
According to the invention, magnetite, anthraquinone-2-sulfonic acid or alkyl glycoside is added under alkaline conditions, so that the hydrolysis of complex macromolecular organic matters into soluble micromolecular organic matters can be promoted, the conversion and utilization of hydrolytic acidification bacteria on the soluble organic matters are facilitated, the activity of hydrolytic enzyme in an anaerobic hydrolytic acidification system is improved, the enrichment of different acidogenic bacterial groups in the system is induced, and the generation of VFAs is facilitated.
The invention carries out centrifugal treatment on the anaerobic hydrolysis acidification product, removes the sludge at the bottom, and leaves supernatant, wherein the supernatant is the anaerobic hydrolysis acidification liquid of the kitchen waste. As an alternative embodiment, the invention centrifugates the anaerobic hydrolysis acidification product for 8 to 10min,7500 to 8500rpm, removes the bottom sludge and leaves the supernatant.
The invention eliminates the mixed bacteria of the anaerobic hydrolysis acidification liquid of the kitchen waste, and then dilutes the anaerobic hydrolysis acidification liquid to the concentration of 2000-2400 mg/L for inoculating rhodopseudomonas palustris. The method for eliminating the mixed bacteria is preferably membrane filtration or high-pressure steam sterilization by adopting a bacterial filter membrane (0.22 mu m); the dilution is preferably water dilution, and the concentration of the diluted anaerobic hydrolysis acidification liquor of the kitchen waste is 2000-2400 mg/L, preferably 2200-2300 mg/L, and more preferably 2202-2220 mg/L. The invention avoids the influence of other strains on rhodopseudomonas palustris by eliminating the mixed bacteria; the dilution ensures proper substrate concentration and abundant nutrient substances in the hydrolyzed acidification liquor, mainly performs cell growth and proliferation of strains and synthesis of PHA, mainly performs PHA synthesis in physiological activities, and improves PHA synthesis rate.
The inoculation amount of the rhodopseudomonas palustris is 13-16%, preferably 14-15%. As an alternative embodiment, the invention provides for the expanded culture of rhodopseudomonas palustris prior to inoculation. The invention does not limit the condition of the expansion culture of rhodopseudomonas palustris.
The culture conditions for synthesizing PHA by rhodopseudomonas palustris are as follows: the illumination intensity is 1800-2200 lux, preferably 2000lux; the rotation speed is 160-200 rpm, preferably 170-180 rpm; the reaction temperature is 28-32 ℃, preferably 29-30 ℃; the initial pH value is 7.8-8.2, preferably pH value 8; the time is 28 to 32 days, preferably 29 to 30 days.
The PHA extraction mode of the invention is preferably SDS-sodium hypochlorite method. As an alternative embodiment, the cultured rhodopseudomonas palustris is taken, freeze-dried thalli thereof are added into SDS solution for stirring, deionized water is used for washing, supernatant is poured, sediment is washed by water, 30 percent sodium hypochlorite solution is added at room temperature for stirring reaction for 3min, deionized water is used for washing immediately, sediment is washed by water again, sediment is dried, a dried sample is put into a condensing reflux device, chloroform is added, water bath is used for heating, and then the mixture is put into an oven for drying, so that a powdery PHA crude product with the main component of PHB is obtained.
The invention also provides application of the method in kitchen waste treatment or polyhydroxyalkanoate industrial production, thereby ensuring the recycling treatment of the kitchen waste and reducing the production cost of PHA.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In a specific embodiment, the kitchen waste is taken from a dining hall of Beijing university chemical industry, and the impurities such as bones, eggshells, fishbone and the like in the kitchen waste are manually picked out, crushed and stored in a refrigerator at the temperature of minus 20 ℃. The rhodopseudomonas palustris is purchased from China industry microbiological culture collection center, and is numbered as CICC 23812. The anaerobic inoculated sludge is taken from the discharge of an anaerobic digestion tank of a municipal sewage treatment plant in Beijing, the inoculated sludge is placed in a shade place for a period of time, the supernatant is removed, and the inoculated sludge is stored in a refrigerator at 4 ℃. The ultrasonic equipment used was a double frequency air ultrasonic cleaner (KQ-300 VDE). The rhodopseudomonas palustris culture medium is tryptone soybean agar culture medium.
In a specific embodiment, the VFAs assay method is: taking a proper amount of anaerobic hydrolysis acidification liquid, centrifuging at 10000rpm for 10min, taking supernatant, dripping phosphoric acid, centrifuging at 10000rpm for 10min again, taking supernatant, filtering a membrane, dripping phosphoric acid, and measuring by using a gas chromatograph FID detector. The chromatographic analysis used was GC1120, FID detector from Shunhai Hengping.
The Polyhydroxyalkanoate (PHAs) measurement method comprises the following steps: solid phase extraction-gas chromatography. The chromatographic analysis was carried out by using the GC1120, FID detector from Shunhai Hengping.
The quality standard curves of PHB and PHV are drawn as follows:
(1) 0.7mg, 2.4mg, 2.9mg, 4.3mg, 4.8mg, 6mg, 8.1mg and 10.1mg of pure PHB standard substances are accurately weighed by weighing paper. 0.8mg, 1.7mg, 3.5mg, 4.5mg, 6mg, 10.7mg, 21.2mg and 32.3mg of copolymer standard. The PHV content was 0.07mg, 0.15mg, 0.31mg, 0.41mg, 0.54mg, 0.96mg, 1.90mg, 2.91mg, respectively.
(2) Pouring the sample into a digestion tube, sequentially adding chloroform and benzoic acid-methanol solution, uniformly mixing, and then digesting for 6 hours in a digestion instrument.
(3) After digestion, adding 1mL of deionized water, shaking and mixing, standing in a refrigerator, sucking 1mL of the lower organic solvent into a sample injection bottle by using a needle tube, and detecting by using a gas chromatograph. PHB off-peak time: 2-2.9 min, PHV peak time: 3.5 to 4 minutes. The standard curve is shown in FIG. 1.
PHB and PHV standards were purchased from Sigma, USA, wherein the PHV content of the copolymer was 9wt%, and wherein the PHB and PHV standard curves were the relationship between PHB, PHV and peak area ratio.
The acidified solution obtained in example was freeze-dried, weighed and the weight of the dried sample (about 50 mg) was recorded, added to a digestion vessel, 2mL of chloroform and 2mL of benzoic acid-methanol were added, and after mixing, the mixture was put into a digestion instrument (105 ℃) for digestion for 6 hours. After cooling, 1mL of ultrapure water was added, mixed by shaking, placed in a refrigerator, allowed to stand still for delamination, the supernatant was taken, and subjected to membrane filtration (0.22 μm), followed by detection in a gas chromatograph.
In a specific example, the index measurement reference standard GB 11914-89, chemical Oxygen Demand (COD) is measured by the potassium dichromate method. Ammonia nitrogen was measured using the Nash reagent method. The pH was measured using a pH meter (Metler-FE 28). Biogas production was measured by a drainage method. The composition of the gas sample was measured by a gas chromatograph (GC 1120/TCD, shunkan).
Example 1
The present example provides a method for synthesizing polyhydroxyalkanoate:
(1) Taking stored kitchen waste, gradually adding Ca (OH) 2 The pH was adjusted to 9 and then sonicated for 10min at 80 kHz.
(2) Anaerobic hydrolytic acidification is carried out on the treated kitchen waste: the effective volume of the experimental reactor is 0.4L, the load of the feeding kitchen waste is set to be 30gVS/L, the load of the inoculation mud is set to be 15gVS/L, the temperature is 35 ℃, the pH value is 9, and the reaction time is 7d. Centrifuging the anaerobic hydrolysis acidification solution for 10min (8000 r/min), removing the bottom sludge, collecting supernatant, and temporarily storing in a refrigerator at 4deg.C.
(3) Performing expansion culture on rhodopseudomonas palustris: in an aerobic environment, rhodopseudomonas palustris liquid is added into a 150mL conical flask, the pH value is adjusted to 7.3, the temperature is set to 30 ℃, and the rhodopseudomonas palustris liquid is cultured for 5 days under the condition of rotating at 180 rpm.
(4) The supernatant of the anaerobic hydrolysis acidification liquid of the kitchen waste is subjected to membrane (0.22 μm) treatment, diluted to 2202mg/L, then added into a 150mL culture bottle together with the cultured rhodopseudomonas palustris liquid, placed into a constant temperature shaking box to synthesize PHA, and experimental conditions are set as follows: the inoculum size of the bacterial liquid is 15%, the illumination intensity is 2000lux, the rotating speed is 180rpm, the reaction temperature is 30 ℃, the initial pH value is 8, and the bacterial liquid is operated for 30 days under the condition.
(5) The cultured rhodopseudomonas palustris is freeze-dried, the weight of the dried sample (about 50 mg) is weighed and recorded, the dried sample is added into a digestion tube, 2mL of chloroform and 2mL of benzoic acid-methanol are added, and after uniform mixing, the mixture is put into a digestion instrument (105 ℃) for digestion for 6 hours. After cooling, 1mL of ultrapure water was added, mixed by shaking, placed in a refrigerator, allowed to stand still for delamination, the supernatant was taken, and subjected to membrane filtration (0.22 μm), followed by detection in a gas chromatograph. The PHA synthesis rate was 42.33%.
(6) Extracting PHA by adopting an SDS-sodium hypochlorite method: taking 2g of cultured rhodopseudomonas palustris, adding SDS solution (50 ℃, stirring for 10 min), washing with deionized water (4000 rpm, centrifuging for 15 min), pouring supernatant, washing precipitate with water (4000 rpm, centrifuging for 15 min), adding 30% sodium hypochlorite solution at room temperature, stirring for 3min, immediately washing with deionized water (4000 rpm, centrifuging for 20 min), washing precipitate with water again (4000 rpm, centrifuging for 20 min), drying precipitate (60-70 ℃ oven drying), putting the dried sample into a condensing reflux device, adding chloroform, heating in a 60 ℃ water bath, and then putting the sample into an oven of 60-70 ℃ for drying to obtain PHA crude product. PHA content was 53.98%.
Example 2
This embodiment differs from embodiment 1 in that: ca (OH) 2 The PHA synthesis rate was 40.89% by replacing KOH.
Example 3
This embodiment differs from embodiment 1 in that: ca (OH) 2 The PHA synthesis rate was 41.56% instead of NaOH.
Example 4
This embodiment differs from embodiment 1 in that: the pH value is adjusted to 8.8 in the step (1), and the PHA synthesis rate is 41.13%.
Example 5
This embodiment differs from embodiment 1 in that: in the step (1), the ultrasonic time is 9min, and the PHA synthesis rate is 40.98%.
Example 6
This embodiment differs from embodiment 1 in that: in the step (2), the feeding kitchen waste load is 27gVS/L, the inoculation mud load is 15gVS/L, the temperature is 34 ℃, the pH value is 9.2, the time is 8d, and the PHA synthesis rate is 37.46%.
Example 7
This embodiment differs from embodiment 1 in that: the anaerobic hydrolysis acidification system in the step (2) is added with 10g/L Fe 3 O 4 The PHA synthesis rate was 46.33%.
Example 8
This embodiment differs from embodiment 1 in that: 120mg/L of AQS and PHA in the anaerobic hydrolysis acidification system in the step (2) have a synthesis rate of 45.68 percent.
Example 9
This embodiment differs from embodiment 1 in that: 9.45g/L of APG06 in the anaerobic hydrolysis acidification system in the step (2) has the PHA synthesis rate of 44.16 percent.
Example 10
This embodiment differs from embodiment 1 in that: and (3) sterilizing the supernatant of the anaerobic hydrolysis acidification liquid of the kitchen waste in the step (4) by high-pressure steam at 121 ℃ for 15min, wherein the PHA synthesis rate is 41.23%.
Example 11
This embodiment differs from embodiment 1 in that: and (3) diluting the anaerobic hydrolysis acidification liquid of the kitchen waste in the step (4) to 2250mg/L, wherein the PHA synthesis rate is 42.05%.
Example 12
This embodiment differs from embodiment 1 in that: the inoculation amount of rhodopseudomonas palustris in the step (4) is 14 percent, and the PHA synthesis rate is 41.61 percent.
Example 13
This embodiment differs from embodiment 1 in that: in the step (4), the illumination intensity is 2100lux, the rotating speed is 190rpm, the reaction temperature is 29 ℃, the initial pH value is 7.9, the operation is carried out for 30 days, and the PHA synthesis rate is 38.76%.
Comparative example 1
The difference between this comparative example and example 1 is that: omitting the step (1), the crushed kitchen waste is directly subjected to anaerobic hydrolysis acidification, the content of VFAs in the kitchen waste anaerobic hydrolysis acidification liquid is 2800mg/L, and the PHA synthesis rate is 28.56%. According to detection, compared with comparative example 1, the yield of the VFAs in the anaerobic hydrolysis acidification liquor of the kitchen waste in the example 1 (7838 mg/L) can be improved by 1.8 times.
Comparative example 2
The difference between this comparative example and example 1 is that: rhodopseudomonas palustris is replaced by rhodobacter sphaeroides.
Comparative example 3
The difference between this comparative example and example 1 is that: rhodopseudomonas palustris is replaced by rhodobacter capsulatus.
The PHA synthesis rates in comparative examples 2 and 3 were detected to be about 35.65% and 34.14%, respectively. The PHA synthesis rate in example 1 was significantly improved over comparative examples 2 to 3.
Test example 1
The ultrasound-base combined pretreatment conditions were verified, 3 replicates per set of experiments:
the ultrasonic time was set to 5min, 10min, 20min, 30min in order, and the initial pH was set to 7.5 (initial pH), 8, 9, 10, 11, 12, respectively in order. The rest of the experimental conditions were the same as in example 1. And after the anaerobic hydrolysis acidification is finished, detecting the obtained anaerobic hydrolysis acidification acidizing fluid in each group.
(1) The VFAs content of each group of anaerobic hydrolytic acidification is tested and the results are shown in table 1 and fig. 2.
TABLE 1 VFAs content (mg/L) in anaerobic hydrolysis acidification liquor
As can be seen from Table 1 and FIG. 2, the initial pH adjustment at an ultrasonic time of 10min caused the production of a significant amount of VFAs in the system, with a VFAs concentration of between 4024 and 7838 mg/L. The VFAs concentration was 7838mg/L at a maximum at an initial pH of 9.0, 94.8% higher than the unconditioned group, and the initial pH was adjusted to give the most remarkable hydrolytic acidification promotion effect. As pH increases, the systemic acidogenesis decreases compared to ph=9.0 group. At initial conditions of ph=11, ph=12, VFAs yields are low and there is little methane production, as the extremely alkaline environment affects the activity of the enzyme, thereby inhibiting microbial growth metabolism. The ultrasonic and alkali combined pretreatment of the kitchen waste has the effect of promoting the generation of the VFAs. And the ultrasonic pretreatment time is 10min, and the acid production effect is optimal when the initial pH is 9.
(2) The contents of acetic acid and butyric acid in each group were measured, and the results are shown in FIGS. 3 to 4.
As can be seen from FIG. 3, the concentration of acetic acid was significantly higher than that of the other groups at a sonication time of 10min. When the initial pH is 7.5, the activity of the methanogenic bacteria is better, so that the generated acetic acid is consumed by the methanogenic bacteria to cause the content of the acetic acid to be low, and the highest concentration of the acetic acid occurs at 36h of 1523.43mg/L. At an initial pH of 9, the acetic acid concentration was higher, 2855.98mg/L, and the VFAs gradually decreased with increasing ultrasonic time. By adjusting the initial pH, the activity of the methanogenic microorganisms is inhibited, and most of the acetic acid is not utilized, allowing a significant accumulation of acetic acid in the system. At pH 11.0 and 12.0, acetic acid production accumulates little because the pH is high and the hydrolytic acidification activity is inhibited, which does not decompose the organics in the system well.
As can be seen from fig. 4, the increase in butyrate production from the initial pH-adjusted group compared to the non-adjusted group suggests that the adjustment of the initial pH may promote butyrate production. The pH is adjusted to increase the dissolution of soluble organic matters in the system and reduce the content of undissociated VFAs so as to promote the production of butyric acid. When the ultrasonic time was 10min, the butyric acid concentration was increased to 2486.46mg/L by adjusting the pH. At pH 11.0 and 12.0, the butyrate content was significantly lower than the other groups, because the pH was higher, inhibiting the activity of the relevant enzyme, resulting in reduced butyrate production.
FIGS. 3-4 show that the pH is high, the anaerobic hydrolysis acidification acid production is greatly promoted, and the methanogen process is inhibited, so that the methanogen cannot timely decompose the generated volatile fatty acids such as acetic acid, butyric acid, propionic acid and the like. In the anaerobic hydrolysis acidification process of the kitchen waste, the VFAs are mainly acetic acid and butyric acid, the content of butyric acid and acetic acid exceeds 60.00%, and the VFAs are butyric acid type acidification and can be used for accumulating a large amount of available VFAs subsequently. When the ultrasonic pretreatment time is 10min and the initial pH is 9.0, the content of butyric acid and acetic acid is higher, so that the subsequent PHA yield can be effectively improved.
(3) The gas yield and methane yield changes in each group of hydrolysis acidification stage are detected, and the results are shown in Table 2.
Table 2 changes in gas yield and methane yield at the hydrolysis and acidification stage of each group of kitchen wastes
As can be seen from Table 2, the methane yield was relatively high at initial pH's of 7.5 and 8.0, indicating that lower pH's also favoured the survival of methanogenic bacteria, so that VFAs produced by anaerobic hydrolytic acidification were not yet accumulated and were consumed by methanogenic bacteria. At initial pH's of 9.0 and 10.0, there is relatively little methane production, indicating that the addition of lye affects the growth metabolism of methanogens in the system, and is unable to timely degrade VFAs in the system, thereby causing significant accumulation of VFAs. After the initial pH is adjusted, the pH change in the system is in a proper range of hydrolytic acidification bacteria, and the activity of methanogen can be inhibited, so that a large amount of VFAs are generated in the system. When the initial pH is 11.0 and 12.0, almost no methane is generated in 64 hours, the amount of methane generated later is small, the pH in the reaction system is 8.6-10.0, the activity of hydrolytic acidification is also inhibited, and anaerobic digestion is not easy to carry out under extremely alkaline conditions.
(4) And (3) carrying out scanning electron microscope observation on the kitchen waste subjected to alkali pretreatment, ultrasonic pretreatment and ultrasonic alkali combined pretreatment. The results are shown in FIG. 5.
As can be seen from fig. 5, the surface structure of the pretreated kitchen waste is severely broken compared with the surface of the kitchen waste which is not pretreatedBad. Ultrasonic pretreatment destroys the porous medium structure of kitchen waste organic matters through the high oscillation of ultrasonic waves and cavitation effect generated by the ultrasonic pretreatment, and alkali treatment is carried out through OH - The cells of the acidified substrate are destroyed, and simultaneously, the saponified protein and the polysaccharide are hydrolyzed, and the combined action of the two can better promote the hydrolysis of organic matters in the kitchen waste, thereby being beneficial to the accumulation of VFAs.
(5) Methanogens were observed using an ultraviolet fluorescence microscope and the results are shown in FIG. 6. As can be seen from fig. 6, the group having an initial pH of 7.5 had a larger number of methanogens at 4d, and the number of methanogens in the experimental group decreased with increasing initial pH. At initial pH values of 11.0 and 12.0, almost no methanogens were observed and sludge flocculation was poor. The results indicate that proper pH adjustment can reduce VFAs consumption and thereby increase VFAs production, but that too high a pH is detrimental to microbial growth metabolism.
Test example 2
Foreign substance Fe 3 O 4 The amount of addition was verified, 3 replicates were run per set of experiments:
setting Fe 3 O 4 The addition amount is 0, 1, 2.5, 5, 10 and 15g/L in sequence, and the rest experimental conditions are the same as in example 7; and after the anaerobic hydrolysis acidification is finished, detecting the obtained anaerobic hydrolysis acidification liquid in each group.
(1) Detection of different Fe 3 O 4 Effect of the amount added on VFAs yield and composition.
Fe 3 O 4 The effect of dosing on VFAs yield is shown in figure 7. As can be seen from FIG. 7, when Fe is initially 3 O 4 When the addition amount of (1 g/L and 2.5 g/L) is low, the promotion effect on acid production is not obvious, the generation amount of VFAs is 8950.92mg/L and 9860.13mg/L respectively, and Fe is not added 3 O 4 The VFAs yield (7238 mg/L) of the control group was 1.24 and 1.36 times. While when Fe 3 O 4 When the addition amount is 5g/L, the yield of the VFAs is obviously increased, and when the yield of the VFAs is 16650.12mg/L, the VFAs is free from adding Fe 3 O 4 2.30 times the VFAs yield of the blank group. When the initial addition amount is 10g/L, the output of the VFAs is 22813.56mg/L at the highest, and the Fe is not added 3 O 4 Is 3.15 times the yield of VFAs for the blank group.However, at an initial dosage of 15g/L, the VFAs yield was 13427.00mg/L, which was 1.85 times that of the control group. Because when Fe is 3 O 4 The excessive addition amount inhibits the activity of hydrolytic acidification flora and influences the normal growth metabolism of the hydrolytic acidification flora, so that the acid production capacity of the system is reduced, the VFAs yield is reduced, but the yield is still higher than that of the VFAs without addition of Fe 3 O 4 Is a control group of (c).
Adding Fe 3 O 4 The VFAs component distribution is shown in FIG. 8, and FIG. 8 shows the composition of each component of VFAs at 4d of acidification. As can be seen from FIG. 8, the most productive VFAs in each group were acetic acid and butyric acid after 4d acidification. Whereas propionic acid, isobutyric acid and valeric acid are less formed throughout the hydrolytic acidification. When Fe is 3 O 4 When the adding amount is 10g/L, the acetic acid concentration reaches 9004.86mg/L, and the butyric acid concentration reaches 8777.07mg/L. Wherein the acetic acid content is increased by 2.04 times, the butyric acid content is increased by 2.52 times, and the sum of the acetic acid content and the butyric acid content accounts for 80.53 percent of the VFAs, thus being typical butyric acid type acidification. Fe is added to 3 O 4 Is put into an anaerobic hydrolytic acidification system and can be used as an electron acceptor to simultaneously produce Fe 2+ The hydrolysis acidification process is enhanced, so that the yield of acetic acid and butyric acid is improved, and the yield of VFAs can be improved.
(2) Detection of Fe 3 O 4 (10 g/L) the effect of the addition on the activity of the enzymes involved in the conversion of acetic acid and butyric acid during the acidification of the anaerobic hydrolysis is shown in Table 3. Blank groups were subjected to ultrasonic-alkali pretreatment only.
TABLE 3Fe 3 O 4 Enzyme activity related to acidification stage after addition
As can be seen from Table 3, the activity of the enzyme related to acetic acid and butyric acid in the experimental group FW+IS (subjected to ultrasonic-alkali pretreatment alone) was significantly lower than that of FW+IS+Fe 3 O 4 Group (3). The increase rate of acetate kinase in FW+IS group was 15.38%, and the increase rate of butyrate was 42.31%. When Fe is 3 O 4 When the addition amount is 10g/L, the acetate kinase increase rate can reach 90.77%, and the butyrate kinase increase rate can reach 291.27%.
Test example 3
The amount of exogenous material AQS addition was verified, 3 replicates were run per set of experiments:
setting the addition amount of AQS to be 0, 40, 80, 120, 160 and 200mg/L in sequence, and the rest experimental conditions are the same as those of the example 8; and after the anaerobic hydrolysis acidification is finished, detecting the obtained anaerobic hydrolysis acidification liquid in each group.
(1) The effect of different AQS dosing amounts on VFAs yield and composition was examined.
The effect of AQS dosing on VFAs yield is shown in figure 9. As can be seen from fig. 9, the yield of VFAs produced during anaerobic hydrolytic acidification tended to decrease after increasing with the larger initial AQS dosage. When the AQS dosage is 0mg/L, the VFAs yield is 7738mg/L, and when the initial AQS dosage is 40mg/L and 80mg/L, the VFAs yield can reach 8721.00mg/L and 10382.65mg/L. Under the condition that the dosage of the AQS is 120mg/L, the maximum VFAs is 18130.21mg/L. When the AQS dosage is 160mg/L and 200mg/L, the maximum VFAs yield is 16247.10mg/L and 11797.30mg/L respectively. The VFAs yield after the addition of AQS is 1.13-2.34 times higher than that of the control group.
The distribution of the VFAs components when the AQS is added is shown in figure 10, and the figure 10 shows the composition of the VFAs components at the time of 4 d. As can be seen from fig. 10, as the AQS dosage increases, the butyric acid and acetic acid contents in the system gradually increase, and the propionic acid and valeric acid contents decrease. The maximum concentration of acetic acid reaches 7526.42mg/L and the maximum concentration of butyric acid reaches 6897.65mg/L when the dosage of AQS is 120 mg/L. Wherein the acetic acid content is increased by 1.54 times, the butyric acid content is increased by 1.77 times, and the sum of the acetic acid content and the butyric acid content accounts for more than 70 percent of the total VFAs. The oxidation-reduction potential of the AQS can be reduced by putting the AQS into an anaerobic hydrolysis acidification system, and the environment is favorable for the production of butyric acid and acetic acid. The AQS can accelerate electron transfer, reduce the activation energy of reaction and promote the degradation of organic matters, so that the VFAs content in the system is increased.
(2) The effect of AQS (120 mg/L) addition on the activity of acetic acid and butyrate conversion related enzymes during anaerobic hydrolytic acidification was examined and the results are shown in table 4. Blank groups were subjected to ultrasonic-alkali pretreatment only.
TABLE 4 enzyme Activity associated with post-acidification stage after AQS addition
As is clear from Table 4, the increase rate of acetate kinase activity was 63.07% and the increase rate of butyrate kinase activity was 230.00% after the addition of AQS, and the activity was 1.63 to 3.30 times higher than that of the enzyme without the addition of AQS. Experimental results show that the addition of the AQS can promote anaerobic hydrolysis acidification of the kitchen waste.
Test example 4
The addition amount of the exogenous substance APG06 is verified, and 3 experiments are performed in parallel:
setting the addition amount of APG06 to be 0, 3.15, 6.3, 9.45, 12.6 and 15.75g/L in sequence, and the rest experimental conditions are the same as in example 9; and after the anaerobic hydrolysis acidification is finished, detecting each group of anaerobic hydrolysis acidification liquid.
(1) The effect of different APG06 dosing amounts on VFAs yield and composition was examined.
The effect of APG06 dosing on VFAs yield is shown in figure 11. As can be seen from fig. 11, the yield of VFAs produced during anaerobic hydrolytic acidification also tended to decrease after increasing with the larger initial APG06 addition. When the initial APG06 dosing amounts were 3.15g/L and 6.31g/L, the maximum VFAs yields appeared to be 4d, 8250.92mg/L and 9260.13mg/L, respectively. When the dosage reaches 9.45g/L, the increase of the VFAs yield is obvious, and the VFAs yield is 16650.13mg/L, which is 2.3 times higher than that of the control group. When the dosage is 12.6g/L and 15.77g/L, the maximum output of the VFAs appears at the 4d, and can reach 11452.58mg/L and 8814.01mg/L respectively.
The distribution of the components of the VFAs when APG06 is added is shown in figure 12, and the figure 12 shows the composition of the components of the VFAs at the 4d time. As can be seen from fig. 12, the VFAs components in the acidification system are mainly acetic acid and butyric acid. As the dosage of APG06 increases, the propionic acid content increases with the increase, but the increase amplitude is smaller, and propionic acid type fermentation is not formed. When the dosage of APG06 is 9.45g/L, the contents of acetic acid, propionic acid and butyric acid are 37.07%, 14.94% and 36.58% respectively. This increased the propionic acid content by a factor of 1.56 and the acetic acid and butyric acid content by a factor of 99.73% and 1.34, respectively, compared to the contemporaneous control group. When the dosage of APG06 was further increased to 12.60g/L and 15.75g/L, the percentages of acetic acid, propionic acid, butyric acid were increased to 41.92%,16.61%,37.16% and 37.16%, 23.56%, 33.85%. APG06 as a surfactant reduces interfacial tension and increases the solubility of organic matters so as to improve the acid production effect of anaerobic hydrolysis.
(2) The effect of APG06 (9.45 g/L) addition on the activity of acetic acid and butyric acid conversion related enzymes during anaerobic hydrolytic acidification was examined and the results are shown in Table 5. Blank groups were subjected to ultrasonic-alkali pretreatment only.
TABLE 5 enzymatic Activity associated with the acidification stage following APG06 addition
As is clear from Table 5, after APG06 was added to the acidification acid production system, the activities of acetate kinase and butyrate kinase were increased to 0.96U/g VSS and 50.42U/g VSS, and the activities were increased by 47.69% and 140.55% as compared with the control group. It is possible that the addition of APG06 releases the butyrate and acetate kinases originally embedded in the solid particles into the acidizing fluid, thereby promoting the hydrolytic acidification.
Test example 5
The rhodopseudomonas palustris culture conditions were verified, and 3 replicates were performed for each set of experiments:
(1) The culture time was set to 15, 20, 25, 30, 35 days in this order. Experimental conditions: 10g/L Fe is added into an anaerobic hydrolytic acidification system for producing VFAs 3 O 4 The seed culture was inoculated at 10% and the pH at 7.3 during PHA synthesis, and the other conditions were the same as those in example 1. After completion of the culture, PHA synthesis rates of each group were measured, and the results are shown in FIG. 13.
As is clear from FIG. 13, the PHA synthesis rate was highest at 30d in the above experimental conditions, and was 34.60%. With increasing time, PHA synthesis rate showed a decreasing trend. In the light anaerobic system for synthesizing PHA, rhodopseudomonas palustris mainly used for producing PHA by utilizing VFAs, and polysaccharide can be ingested into cells to participate in PHA synthesis, and protein is involved in the composition of cell frameworks, enzyme synthesis and the like. As the reaction time increased, most of the VFAs in the system were consumed, and Rhodopseudomonas palustris degraded in intracellular PHA to meet the growth and metabolism demands, indicating that the culture time was optimal at 30d.
(2) The anaerobic hydrolysis acidification liquid obtained in example 1 was diluted 5 times, 10 times (2202.21 mg/L), 20 times, 40 times and 60 times in sequence. Experimental conditions: 10g/L Fe is added into an anaerobic hydrolytic acidification system for producing VFAs 3 O 4 The seed culture was inoculated at 10% and the pH at 7.3 during PHA synthesis, and the other conditions were the same as those in example 1. After completion of the culture, PHA synthesis rates of each group were measured, and the results are shown in FIG. 14.
As is clear from FIG. 14, when the substrate concentration was 2202.21mg/L (dilution factor was 10), the PHA synthesis effect was best, and the synthesis rate was 34.80%. This is because when the concentration of the substrate in the acidified solution is appropriate and the nutrient is abundant, the cell growth and proliferation of the strain and the synthesis of PHA are mainly performed, and the PHA synthesis is mainly performed in the main physiological activities, and the PHA synthesis rate is high at this time; the acidifying liquid has low substrate concentration and deficient nutrient, and rhodopseudomonas palustris mainly used for maintaining the carbon source and the energy source of the life activities of the rhodopseudomonas palustris and the growth and reproduction of cells by using the nutrient taken in the environment and intracellular polymers (such as PHA), so that the PHA synthesis rate is low. And when the concentration of the substrate is low, the ingestion of the rhodopseudomonas palustris to the substrate can be influenced, so that the PHA bacteria grow too slowly and the PHA synthesis efficiency is low. Too high a substrate concentration may have an adverse effect on rhodopseudomonas palustris, since too much VFA can penetrate into the cells resulting in a decrease in intracellular pH and thus affecting the microbial PHA synthesis. Indicating that the concentration of the anaerobic hydrolysis acidification liquid is optimally diluted to 2202.21 mg/L.
(3) The initial pH values of the culture were set to 6.5, 7, 7.5, 8, 8.5 in this order. Experimental conditions: 10g/L Fe is added into an anaerobic hydrolytic acidification system for producing VFAs 3 O 4 The seed culture for PHA synthesis was 10%, and the other experimental conditions were the same as in example 1. After completion of the culture, PHA synthesis rates of each group were measured, and the results are shown in FIG. 15.
As is clear from FIG. 15, when the pH is 6.5, the normal vital activity of rhodopseudomonas palustris is affected, probably because the pH in the reaction system is too low and the cell permeability and enzyme activity of rhodopseudomonas palustris are inhibited. When the pH is raised to 7.0 and 8.0, the PHA synthesis rate is high, up to 40.12%, and is obviously higher than other pH conditions. Under the condition of low pH value, acetic acid is not easy to be absorbed and utilized by rhodopseudomonas palustris, and undissociated acetic acid can be rapidly diffused into bacteria to reduce the pH value, so that PHA synthesis is not facilitated; when PHA accumulation occurs at higher pH, the cells are driven to sustain vital activity rather than PHA accumulation due to the higher energy requirements. Indicating an initial pH of 8 for the culture.
(4) The inoculum size of rhodopseudomonas palustris was set to 5%, 10%, 15%, 20% and 25% in this order. The rest of the experimental conditions were the same as in example 1. After completion of the culture, PHA synthesis rates of each group were measured, and the results are shown in FIG. 16.
As can be seen from FIG. 16, when the inoculum size was 5%, the PHA synthesis rate was low by only 27.80%, the VFAs were degraded relatively slowly and the COD and ammonia nitrogen removal rate was low. The inoculation amount is 15%, and the PHA synthesis rate can reach 46.33%. When the inoculum size reaches 25%, although further increasing the inoculum size can further increase the PHA production, the extent is very limited. Indicating that the inoculation amount of rhodopseudomonas palustris is 15% optimal.
Test example 6
Under the substrate conditions of exploring different VFAs components, the synthesis effect of rhodopseudomonas palustris PHA is detected, and each group of experiments is carried out in 3 parallels: the composition of VFAs in the anaerobic hydrolysis acidification liquid of the kitchen waste and the PHB-PHV ratio change in the PHA product in the example 1 are detected, and the result is shown in FIG. 17.
As can be seen from FIG. 17, rhodopseudomonas palustris preferentially utilized for acetic acid, butyric acid, and then propionic acid and valeric acid. Acetic acid, butyric acid, were used up by microorganisms within 25d, whereas propionic acid was consumed after 30d. The difference in the VFAs components of the substrates for PHA synthesis can result in different monomer levels of PHB and PHV. The anaerobic hydrolysis acidification liquid of the kitchen waste is mainly composed of even carbon VFAs such as butyric acid, acetic acid and the like, and the PHV content synthesized by rhodopseudomonas palustris is lower than PHB. The relative content of PHV and PHB changes along with the fermentation, and when the reaction is operated for 30 days, the relative content of PHB and PHV is 96.90% and 3.10% respectively.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (5)
1. A method for synthesizing polyhydroxyalkanoate, comprising the steps of: inoculating rhodopseudomonas palustris into the anaerobic hydrolysis acidification liquid of the kitchen waste for culturing, and extracting polyhydroxyalkanoate in the rhodopseudomonas palustris after the culturing is finished;
the preparation method of the anaerobic hydrolysis acidification liquid for the kitchen waste comprises the following steps: pretreating kitchen waste, performing anaerobic hydrolysis acidification, centrifuging hydrolysis acidification products, and collecting supernatant;
the pretreatment method comprises the following steps: crushing kitchen waste, and then carrying out ultrasonic-alkali combined pretreatment;
the ultrasonic-alkali combined pretreatment conditions are as follows: ultrasonic treatment is carried out for 8-12 min, and the pH value is 8.5-9.5;
the mass ratio of the kitchen waste to the inoculated sludge is 1.5-2.5: 1, mixing and then carrying out anaerobic hydrolytic acidification, wherein the anaerobic conditions are as follows: the pH value is 8.5-9.5, the anaerobic temperature is 33-36 ℃ and the time is 6-8 d;
the culture conditions are as follows: the illumination intensity is 1800-2200 lux, the rotating speed is 160-200 rpm, the reaction temperature is 28-32 ℃, the initial pH value is 7.8-8.2, and the culture time is 28-32 d.
2. The method according to claim 1, wherein one or more of magnetite, anthraquinone-2-sulfonic acid and alkyl glycoside are added to the anaerobic hydrolytic acidification system.
3. The method of claim 1, wherein the anaerobic hydrolysis acidification liquor of the kitchen waste eliminates mixed bacteria, is diluted to a concentration of 2000-2400 mg/L, and is inoculated with rhodopseudomonas palustris.
4. The method according to claim 1, wherein the rhodopseudomonas palustris inoculum size is 13-16%.
5. Use of the method according to any one of claims 1 to 4 for kitchen waste treatment or for industrial production of polyhydroxyalkanoates.
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