Methods for decomposing abandoned, difficult-to-decompose plastics

Abstract

To achieve actual use of microbial decomposition of a hardly decomposable plastic and microbial decomposition of an included addition agent.SOLUTION: A decomposition processing method is configured so that, microbes having a decomposition ability to a hardly decomposable plastic being a processing object, or the above mentioned microbes and microbes having a decomposition ability to an included addition agent included in the plastic, and microbes which can coexist with the respective microbes, are mixed and the mixture is added to the processing object for decomposing the processing object, then plastic decomposition bacteria and bacterial strains between which there is chemistry are combined for constructing a symbiotic relationship. As a composite fermentation possible situation is generated, by construction of the symbiotic environment between microbes, stable growth of plastic decomposition bacteria and maintenance of each decomposition ability can be achieved, thereby promoting decomposition processing of the hardly decomposable plastic and the included addition agent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for decomposing difficult-to-decompose plastics and additives added to plastics. [Background technology]

[0002] Plastics discarded in the natural environment have the problem of remaining indefinitely without being decomposed by microorganisms. To solve this problem, biodegradable plastics that are easily decomposed by microorganisms have been developed, and microorganisms capable of biodegrading difficult-to-decompose plastics have been discovered (Non-Patent Documents 1, 2).

[0003] Furthermore, as disclosed in Patent Document 1, a method is disclosed in which difficult-to-decompose organic food waste is emulsified in a treatment tank, and then eight types of treatment bacteria, mainly Bacillus bacteria, are supported on porous ceramic spheres and introduced at a specified temperature to decompose the waste. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-119355 A. [Non-patent literature]

[0005] [Non-Patent Document 1] "Biodegradability of Polymer Materials and Biodegradability of Hardly Degradable Polymer Materials" by Kosuke Tomita, Journal of Materials Life Science, January 2007, pp. 13-17 [Non-Patent Document 2] Rakuno Gakuen University Animal Medicine Education Center “Topics: The trump card for plastic waste countermeasures: Discovery of plastic-eating bacteria” [online] 2019.07.29 [Retrieved July 22, 2020] Internet<URL:https: / / cvdd.rakuno.ac.jp / archives / 3101.html> Summary of the Invention [Problem to be solved by the invention]

[0006] Plastic-degrading bacteria are microorganisms that do not require large-scale facilities or advanced equipment to decompose plastics and their additives. Furthermore, because microorganisms are self-propagating, if the appropriate environment is provided for their proliferation, they can maintain their ability to decompose plastics for a long period of time, so decomposition processing using plastic-degrading bacteria is considered to be a very promising technology. However, at present, plastic decomposition processing using plastic-degrading bacteria has not been put to practical use.

[0007] The reason for this is thought to be that even if sufficient plastic-degrading and additive-degrading abilities are demonstrated at the laboratory level, there are many microorganisms in the environment, and plastic-degrading bacteria alone are unable to fully demonstrate their capabilities due to competition with other bacteria.

[0008] For this reason, as disclosed in Patent Document 1, for example, in order to aim for comprehensive treatment including plastics as part of organic waste treatment, specific treatment processes and treatment facilities are required, and since it is not intended for plastic waste, it cannot be said to be suitable for the treatment of large amounts of plastic waste.

[0009] Furthermore, some plastic waste contains additives such as plasticizers and flame retardants that are toxic, which poses an environmental pollution problem.

[0010] Therefore, the present invention proposes a novel method for decomposing difficult-to-decompose plastics and the additives contained therein, in which the functions of plastic-decomposing bacteria are fully exerted. [Means for solving the problem]

[0011] The present invention Abandoned, difficult-to-decompose plastics The decomposition method of the present invention is a method for decomposing a plastic that is difficult to decompose, which is a treatment target, by mixing microorganisms capable of decomposing the above-mentioned microorganisms and additives contained in the plastic, and microorganisms capable of coexisting with the above-mentioned microorganisms. Abandoned in its natural environmentAdd to the object to be treated, abandoned The present invention is characterized in that the effect of other microorganisms present in the target material is suppressed, and the target material is decomposed while maintaining the proliferation and decomposition ability of the added microorganisms. The amount of the added microorganisms is 10 6 ~10 pieces 13 The decomposition treatment is carried out for 3 to 180 days.

[0012] The objects to be treated in the present invention are plastics that are difficult to decompose in a short period of time, such as polyethylene resin, polyethylene terephthalate, polystyrene resin, polyvinyl chloride resin, vinylidene chloride resin, polypropylene resin, polyester resin, polyamide resin, methacrylic resin, polyacetal resin, polyphenylene resin, polysulfone resin, fluororesin, polyphenylene sulfide resin, silicone resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, and epoxy resin, and the additives are substances added to plastics as plasticizers, stabilizers, lubricants, crosslinking agents, antioxidants, UV absorbers, fillers, reinforcing agents, reinforcing agents, antistatic agents, flame retardants, flame retardants, foaming agents, fungicides, and pigments.

[0013] The microorganisms used are bacteria of the genus Ideonella, Sphingobium, etc., and filamentous fungi of the genus Penicillium, Aspergillus, etc., that have the ability to degrade difficult-to-degrade plastics, and microorganisms that can coexist symbiotically with the above-mentioned microorganisms are used.

[0014] Generally, when waste plastic is treated in situ (disposal site, washed up shore) with plastic-degrading bacteria, there are many microorganisms present in the environment, and it is assumed that the plastic-degrading bacteria alone are unable to fully exert their capabilities due to competition with other bacteria.

[0015] Therefore, by combining plastic-degrading bacteria with compatible strains of bacteria to form a symbiotic relationship and create conditions for complex fermentation, it becomes possible to create a symbiotic environment between the microorganisms, allowing for stable proliferation of the plastic-degrading bacteria and maintenance of each decomposition ability, thereby accelerating the decomposition process of difficult-to-degrade plastics.

[0016] In addition, various additives are used in plastics to improve their physical properties and make them flame retardant. During the decomposition process of the above-mentioned plastics, various additives are released, and if the additives are harmful substances, environmental pollution becomes a problem. Therefore, by combining plastic-decomposing bacteria that decompose the plastic itself with plastic-decomposing bacteria that decompose toxic additives, the harmful additives released during the decomposition process of the plastic are simultaneously decomposed, making it possible to decompose plastics while suppressing the release of harmful substances into the environment. Effect of the Invention

[0017] The configuration of the present invention is as described above. In the microbial decomposition of difficult-to-degrade plastics (target of treatment), which are difficult to grow alone due to the influence of other microorganisms and therefore difficult to continuously exert their decomposition ability, the use of a mixture of symbiotic microorganisms suppresses the influence of other microorganisms present in the environment (decomposition site), and by maintaining the growth and decomposition ability of the microorganisms, the present invention has made it possible to practically decompose the target of treatment. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a conceptual diagram of a process according to an embodiment of the present invention. [Diagram 2] 16S rRNA region DNA sequence table of the TCM-1 strain used in the verification test. [Diagram 3] DNA sequence table of the 16S rRNA region of the same Na.53 strain. [Figure 4] DNA sequence table of the 16S rRNA region of the same Na.365 strain. [Diagram 5] Table showing the results of the experiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In the present invention, an appropriate amount of a treatment bacteria group consisting of a combination of multiple plastic-degrading bacteria strains A and B and symbiotic bacteria strains C and D that coexist symbiotically with the decomposition bacteria is added to the object to be treated (difficult to decompose plastics) stored in a suitable container or to the object to be treated buried in the soil at a disposal site (such as a site where plastics have washed up at sea), and then left for a considerable period of time, whereby the difficult to decompose plastics are decomposed by complex fermentation by the microorganisms, making it possible to quickly decompose difficult to decompose plastics without the need for large facilities or waste collection work.

[0020] Next, we will explain the experiments for this verification. The strains used were "TCM-1 strain," "No. 53 strain," and "No. 365 strain." The 16S rRNA region DNA sequences of each strain are shown in Figures 2, 3, and 4.

[0021] The "TCM-1 strain" has the following characteristics: "NBRC deposit number: NBRC112374," "genus and species: Sphingobium sp.," "isolation source: sediment," and "body shape: bacillus," and has the ability to degrade tris(2-chloroethyl) phosphate (TCEP), a flame retardant for urethane resins.

[0022] The "No.53 strain" is of the following genus: Pedobacter agri, from which it was isolated: paddy field soil, in which its body shape is: rod-shaped bacterium, and gram staining: negative. It does not inhibit the growth of the TCM-1 strain, and can coexist symbiotically with it. By growing symbiotically with the TCM-1 strain, it suppresses attacks from other bacteria. It can also coexist symbiotically with the No.365 strain, and a combination of the TCM-1, No.53, and No.365 strains is possible.

[0023] "Stock No. 365" is "Genus: Enterococcus haemoperoxidus", "Source of isolation: paddy field soil", "Body shape: streptococcus", "Gram staining: positive", and does not inhibit the growth of the TCM-1 strain, but can coexist symbiotically. By growing symbiotically with the TCM-1 strain, it suppresses attacks from other bacteria. It can also coexist symbiotically with the No. 365 strain, and a combination of the TCM-1, No. 53 and No. 365 strains is possible.

[0024] In the demonstration experiment, in order to reproduce a pseudo-competitive environment (soil), insoluble silicate clay, the main component of which is silicate, was mixed with a 1 / 5 diluted dry bouillon medium, and plastic-degrading bacteria and multiple microbial strains were added to confirm whether the degradation of the flame retardant TCEP could be maintained. The media used were a 1 / 5 diluted dry bouillon medium with silicate clay added (1 / 5 NB medium with silicate clay added), a dry bouillon medium (for pre-culture), and a dry bouillon plate medium (for measuring the number of bacteria and judging colonies).

[0025] The demonstration experiment was conducted as follows. 1. Place 1g of silicate clay in a Wassermann test tube. 2. Dispense 4 ml of 1 / 5 diluted NB medium into a Wassermann tube. 3. Add TCEP to a concentration of 20 μM. 4. Mix using a vortex mixer for 1 minute. 5. Sterilize at 21℃ for 15 minutes. 6. After cooling, inoculate 50 μl of each strain and mix. 7. Static culture is carried out at 30℃ (culture time is 7 or 14 days). 8. After incubation, mix for 1 minute using a vortex mixer. 9. After stirring, a sample is taken to measure the number of bacteria. The remaining culture liquid is centrifuged to remove the bacteria and silicic acid clay, and the TCEP decomposition ability is measured.

[0026] The test results are shown in Figure 5. In addition, the "test group strain" in Figure 5 indicates "strain No. 365." From these results, it was found that the concentration of 2-chloroethanol, a decomposition product of TCEP, tended to be higher in the control group than in the test group after 7 days of culture, but conversely, the test group showed a tendency to have a higher concentration of 2-chloroethanol after 14 days of culture.

[0027] This is because the results of the bacterial count measurements showed that the number of TCM-1 strain bacteria in the test area was on the rise even on the 14th day of cultivation, while in the control area it was on the decline, which may have led to a decrease in the activity of the TCM-1 strain.

[0028] As a result, in the test area where complex fermentation was carried out by combining multiple symbiotic strains, it was found that a stable microbial flora was maintained, and the decomposition ability of tris(2-chloroethyl) phosphate was maintained for a long period of time.

Claims

1. A method for decomposing abandoned difficult-to-decompose plastics, comprising mixing microorganisms having the ability to decompose the difficult-to-decompose plastics being treated with microorganisms that coexist symbiotically with the said microorganisms, adding the resulting mixture to the object being treated that has been left abandoned in a natural environment, suppressing the effects of other microorganisms present in the abandoned area, and decomposing the object while maintaining the growth and decomposition ability of the added microorganisms.

2. A method for decomposing abandoned difficult-to-decompose plastics, comprising mixing microorganisms capable of decomposing the difficult-to-decompose plastics being treated, and microorganisms capable of decomposing additives contained in the plastics, together with microorganisms capable of coexisting with each of the microorganisms, and adding the resulting mixture to the object being treated that has been left abandoned in a natural environment, thereby suppressing the influence of other microorganisms present in the abandoned area and decomposing the object while maintaining the growth and decomposition ability of the added microorganisms.

3. 3. A method for decomposing abandoned difficult-to-decompose plastics according to claim 2, wherein the microorganism having the ability to decompose additives contained in difficult-to-decompose plastics is the TCM-1 strain (NBRC deposit number: NBRC112374).

4. There are 10 microorganisms per gram of difficult-to-degrade plastic. 6 pieces ~ 10 13 3. The method for decomposing abandoned difficult-to-decompose plastics according to claim 1 or 2, wherein the amount of the additive is so added that the amount of the additive becomes one.

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