Microbial carrier for food waste treatment

Abstract

A microbial carrier for food waste treatment, in which a base resin constituting the microbial carrier contains a thermoplastic starch and / or an aliphatic polyester, the degree of biodegradability of the microbial carrier in a biodegradability test according to JIS K6953 is 60% or more, and the microbial carrier has a columnar shape.

Description

Technical Field

[0001] The invention relates to a microorganism carrier for treating food waste, which carries microorganisms for treating food waste. Background Art

[0002] Most food waste is disposed of by incineration in an incineration plant or landfill. Incineration produces a large amount of waste heat and carbon dioxide, which raises concerns about its impact on the environment. In addition, landfill is difficult to secure.

[0003] Therefore, various technologies for treating food waste by treatment other than incineration and landfilling have been proposed. For example, the technology of biodegrading food waste by microorganisms has little impact on the environment and does not require landfilling. In addition, food waste is decomposed into water and carbon dioxide by microorganisms. The food waste is decomposed by stirring a carrier loaded with microorganisms together with the food waste in a waste treatment device.

[0004] For example, technologies related to carriers for supporting microorganisms are disclosed in Patent Documents 1 and 2. The carrier of Patent Document 1 contains a thermoplastic resin, and the carrier of Patent Document 2 contains polyolefin and polystyrene.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-55562.

[0008] Patent document 2: Japanese Patent No. 6869307. Summary of the invention

[0009] Problems to be solved by the invention

[0010] When a carrier is used for a certain period of time, the biodegradability of the carrier decreases, or the carrier has an odor. Therefore, the carrier is replaced, for example, every two years. As a result, the used carriers in Patent Documents 1 and 2 become a large amount of garbage, so as mentioned above, the carriers need to be incinerated or landfilled. Therefore, for existing carriers, there are problems of environmental impact and securing landfill sites.

[0011] The present invention takes the above situation into consideration, and its object is to provide a microbial carrier for food waste treatment, which has little impact on the environment by eliminating the need for incineration-based carrier treatment or landfill-based carrier treatment, or by sufficiently reducing the amount of discarded carriers.

[0012] Means for solving problems

[0013] [1] A microbial carrier for food waste treatment, wherein the base resin constituting the microbial carrier comprises thermoplastic starch and / or aliphatic polyester, the biodegradability of the microbial carrier in a biodegradability test based on JIS K6953 is 60% or more, and the shape of the microbial carrier is columnar.

[0014] [2] The microbial carrier for food waste treatment according to [1], wherein the arithmetic mean height (Sa) of the surface irregularities of the surface of the microbial carrier is 2.4 μm or more.

[0015] [3] The microbial carrier for food waste treatment as described in [1] or [2], wherein the apparent density of the microbial carrier is 400 kg / m 3 Above and 800kg / m 3 the following.

[0016] [4] The microbial carrier for food waste treatment as described in any one of [1] to [3], wherein the microbial carrier is columnar and has a polygonal cross-sectional shape when cut perpendicularly to the height direction of the microbial carrier.

[0017] [5] The microbial carrier for food waste treatment according to any one of [1] to [4], wherein the plant-based content of the thermoplastic starch or aliphatic polyester according to ASTM D6866 is 40% or more.

[0018] Effects of the Invention

[0019] The microbial carrier for food waste treatment of the present invention can be biodegraded. Therefore, it is not necessary to carry out treatment based on incineration or landfill of the carrier, or the amount of carrier waste is sufficiently reduced, and the impact on the environment can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0021] Figure 2 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0022] Figure 3 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0023] Figure 4 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0024] Figure 5 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0025] Figure 6 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0026] Figure 7 It is a three-dimensional diagram of a carrier according to an example of the present invention.

[0027] Figure 8 This is an electron microscope photograph (magnification 10,000 times) of the surface of the side surface of a carrier according to an example of the present invention. DETAILED DESCRIPTION

[0028] The microbial carrier for food waste treatment of the present invention (hereinafter referred to as "carrier") is a structure for carrying microorganisms for treating food waste. It should be noted that the microbial carrier for food waste treatment of the present invention includes the case where microorganisms are carried and the case where microorganisms are not carried. Food waste refers to the residues generated during the cooking process of food, the leftovers generated during the circulation process of food, and the leftover food generated during the consumption stage of food.

[0029] It should be noted that in the following description, the preferred numerical range of the present invention is sometimes appropriately shown, but in this case, the preferred range, more preferred range, and particularly preferred range related to the upper and lower limits of the numerical range can be determined by all combinations of the upper and lower limits. In addition, "A to B" representing a numerical range is synonymous with "A or more and B or less", and is used as a range including the endpoints (A, B) of the numerical range. In addition, "A and / or B" is a concept including "A and B, A or B".

[0030] The carrier of the present invention can crush food waste. In the treatment device, the carrier is stirred to crush food waste, and the carrier is decomposed into water and carbon dioxide by the microorganisms carried by the carrier. As described above, the carrier has the function of carrying microorganisms and crushing food waste.

[0031] Specifically, the biodegradability of the carrier of the present invention in the biodegradability test of JIS K6953 is 60% or more, preferably 80% or more, and more preferably 90% or more. That is, the carrier of the present invention can be biodegraded by microorganisms. Therefore, the carrier of the present invention does not need to be incinerated or landfilled after use, or the amount of the carrier to be processed is sufficiently reduced.

[0032] The biodegradability test of JIS K6953 is a test in which a test sample (a carrier in the present invention) is placed in aerobic compost (compost with good aeration) and the degree of biodegradability is calculated from the amount of carbon dioxide generated when decomposed by microorganisms.

[0033] The substrate resin of the carrier of the present invention comprises thermoplastic starch and / or aliphatic polyester. That is, the aforementioned substrate resin preferably comprises thermoplastic starch and aliphatic polyester, or comprises thermoplastic starch or aliphatic polyester. Here, the substrate resin refers to a resin that occupies 50% by weight or more, preferably 70% by weight or more, and more preferably 90% or more in 100% by weight of the resin constituting the carrier, and the resin constituting the carrier is preferably composed of the substrate resin.

[0034] The content of the thermoplastic starch and / or aliphatic polyester in the base resin is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more. It should be noted that, when the base resin contains both thermoplastic starch and aliphatic polyester, the content of the thermoplastic starch and / or aliphatic polyester in the base resin is their total amount.

[0035] Thermoplastic starch is a modified starch that makes starch or starch derivatives have thermoplasticity. As thermoplastic starch, for example, some of the three hydroxyl groups of glucose, which is a constituent unit of the starch molecular chain, are converted into hydrophobic groups through etherification, esterification, etc., and a plasticizer such as glycerol or ethylene glycol is added.

[0036] When the base resin does not contain an aliphatic polyester but is composed of thermoplastic starch, the content of the thermoplastic starch in the base resin is, for example, 50 mass % or more, preferably 70 mass % or more, and more preferably 90 mass % or more.

[0037] Aliphatic polyester is an aliphatic polyester containing an aliphatic ester as the main component in the main chain. The content ratio of the aliphatic ester in the main chain is at least 60 mol% or more, preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. Aliphatic polyesters include hydroxy acid polycondensates, ring-opening polymers of lactones, and polycondensates of polyol components and polycarboxylic acid components. As hydroxy acid polycondensates, polylactic acid, polycondensates of hydroxybutyric acid, etc. can be cited. As ring-opening polymers of lactones, polycaprolactone, polypropiolactone, etc. can be cited. As polycondensates of polyol components and polycarboxylic acid components, polybutylene succinate (PBS), polybutylene adipate (PBAT), polyethylene succinate, etc. can be cited. Among them, from the viewpoint of the moldability of the carrier, polylactic acid and polybutylene succinate are preferred.

[0038] When the base resin does not contain thermoplastic starch but is composed of an aliphatic polyester, the content of the aliphatic polyester in the base resin is, for example, 50 mass % or more, preferably 70 mass % or more, and more preferably 90 mass % or more.

[0039] For thermoplastic starch and aliphatic polyester used as the base resin, the biodegradability based on JIS K6953 is preferably 60% or more, more preferably 80% or more, and further preferably 90% or more. It should be noted that the upper limit of the biodegradability is 100%. In addition, for a carrier using the above-mentioned thermoplastic starch and aliphatic polyester as the base resin, it is considered that the biodegradability of the carrier is the same value as the biodegradability of the thermoplastic starch and the aliphatic polyester.

[0040] The plant-based content of at least one of the thermoplastic starch and the aliphatic polyester is preferably 20% or more, more preferably 50% or more, and further preferably 70% or more. By setting the plant-based content of the thermoplastic starch and the aliphatic polyester to the above range, the carbon neutrality effect can be improved and global warming can be suppressed. It should be noted that the plant-based content can be measured by ASTM D6866.

[0041] In addition, the marine decomposition degree of at least one of the thermoplastic starch and the aliphatic polyester is preferably 90% or more. By using the above-mentioned base resin, even if the carrier is damaged during waste treatment and flows into a river or the ocean together with drainage, it can be quickly decomposed. The above-mentioned marine decomposition degree can be measured by ASTM D6691.

[0042] The base resin of the carrier of the present invention may contain other resins other than thermoplastic starch and aliphatic polyester within a range that can maintain the biodegradability of the carrier at 60% or more. Other resins may include, for example, other polymers such as polypropylene resins, polyester resins, polyolefin resins, polyphenylene ether resins, and elastomers. However, the content of other resins in the base resin is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and most preferably 0 (i.e., only thermoplastic starch and / or aliphatic polyester are included as the base resin).

[0043] The carrier may contain various other components within a range that can maintain the biodegradability of the carrier at 60% or more. Other components, such as other additives, include various additives such as foaming agents (physical foaming agents and chemical foaming agents), bubble nucleating agents, plasticizers, colorants such as pigments and dyes, thermal stabilizers, and fillers.

[0044] The structural features of the carrier are as follows.

[0045] [shape]

[0046] Figures 1 to 7 is a three-dimensional image of the carrier. Figures 1 to 7 As exemplified, the carrier of the present invention is columnar. Preferably, the carrier is a structure including a bottom surface, an upper surface, and a side surface located between the bottom surface and the upper surface.

[0047] The cross-sectional area of ​​the carrier (i.e., the area of ​​the bottom and the top) is, for example, 0.5 to 1.4 cm 2 The height of the carrier is 0.8 to 1.3 cm. The cross-sectional area of ​​the carrier is the area of ​​the cross section when it is cut with a plane perpendicular to the height direction x (axial direction) of the carrier. The height of the carrier is, for example, Figure 1 The distance between the bottom and top surfaces of the columnar body.

[0048] Figure 1 It is a carrier with a circular cross-sectional shape. On the other hand, Figures 2 to 7 is a carrier with a polygonal cross-section. Specifically, Figure 2 The cross-sectional shape is a triangle. Figure 3 The cross-sectional shape is a quadrilateral. Figure 3 The cross-sectional shape is a pentagon. Figure 4 The cross-sectional shape is hexagonal. Figure 6 The cross-sectional shape is a cross (a shape where two rectangles intersect orthogonally at the position where the center of gravity coincides). Figure 7 The cross-sectional shape is star-shaped. However, the cross-sectional shape of the carrier is not limited to the above examples. It should be noted that the cross-sectional shape refers to the shape of the cross section when cut with a plane perpendicular to the height direction x of the carrier.

[0049] It can be considered that when the volume is set to be equal, the surface area of ​​the carrier with a polygonal cross-sectional shape is increased compared to the carrier with a circular cross-sectional shape, and the microorganisms are easily fixed, or the crushing property is improved due to the corners, so the decomposition efficiency of food waste is improved. Therefore, the cross-sectional shape of the carrier is preferably a polygon, and more preferably a star shape among polygons. However, the carrier with a circular cross-sectional shape is also included in the present invention.

[0050] [Average particle size]

[0051] The average particle size of the carrier is preferably 5 to 20 mm, more preferably 6 to 15 mm, and further preferably 7 to 13 mm. If the average particle size is within the above range, the handling is excellent. The average particle size can be determined by measuring the average value of the maximum height of the columnar carrier with a vernier caliper or the like. In addition, the volume of each carrier is preferably 0.2 to 1 cm 3 , more preferably 0.3 to 0.8 cm 3 If the volume per carrier is within the above range, the carrier has excellent decomposition performance. The volume per carrier can be calculated based on the apparent density of the carrier and the weight of each carrier measured separately.

[0052] The ratio (L / d) of the average particle size of the carrier to the maximum length in the cross section of the carrier is preferably 1 to 2, more preferably 1.0 to 1.6. When (L / d) is within the above range, the fluidity in the waste treatment device is excellent.

[0053] [Arithmetic mean altitude (Sa)]

[0054] The arithmetic mean height (Sa) of the surface concavoconvex of the carrier surface is preferably 2.4 to 5 μm, more preferably 2.5 to 4.5 μm, further preferably 3.0 to 4.2 μm, and most preferably 3.2 to 4.0 μm. The arithmetic mean height is an index representing the average value of the height difference from the average surface. It can be considered that if the arithmetic mean height (Sa) is within the above range, the surface concavoconvex becomes a resistance when in contact with food waste, and the crushing force is more excellent. By the structure as described above, a concavoconvex structure is formed on the entire surface of the carrier, so the crushing property of the food waste is more excellent. Specifically, for the numerical range of the aforementioned arithmetic mean height (Sa), for example, a range with any one of the group consisting of 2.4 μm, 2.5 μm, 3.0 μm and 3.2 μm as the lower limit and any one of the group consisting of 5 μm, 4.5 μm, 4.2 μm and 4.0 μm as the upper limit can be cited.

[0055] In the present invention, the arithmetic mean height is determined by measuring the surface of the columnar carrier by any known method. For example, in the surface of the carrier photographed by a laser microscope, the arithmetic mean height is determined based on the three-dimensional image of the side and using analytical software. It should be noted that the three-dimensional image used is an image after the shape is flattened using an L-filter (a filter that removes long wavelengths such as ripples and shape components).

[0056] In addition, it is preferred that the surface of the side portion of the columnar carrier be formed with Figure 8 The pores are about 0.3 to 3 μm as shown. When the pores as described above are formed and the carrier is a porous body, the adsorption of microorganisms is particularly excellent. Based on the above viewpoint, the maximum diameter of the pores is preferably 0.3 to 3 μm, preferably 0.5 to 2 μm. It should be noted that the maximum diameter of the pores on the surface of the carrier refers to the absolute maximum length. For the numerical range of the maximum diameter of the aforementioned pores, for example, a range can be cited with any one of the group consisting of 0.3 μm and 0.5 μm as the lower limit and any one of the group consisting of 3 μm and 2 μm as the upper limit.

[0057] In addition, in an electron micrograph of the surface of the side surface of the columnar carrier, it is preferred that 25 to 80 holes with a maximum diameter of 0.3 to 3 μm are formed in an area of ​​100 μm. It should be noted that the number of holes is preferably 10 to 40 holes / 100 μm. 2 The holes as described above can be formed, for example, by using a base resin compounded with thermoplastic starch. Specifically, the number of holes can be, for example, a range with any one of the group consisting of 5, 10, and 30 as the lower limit and any one of the group consisting of 80, 60, and 40 as the upper limit.

[0058] [Apparent density]

[0059] The apparent density of the carrier is preferably 300 to 950 kg / m 3 , more preferably 350 to 900 kg / m 3 , more preferably 400 to 800 kg / m 3 , the most preferred range is 450~750kg / m 3 If it is within the above range, the carrier has a moderate weight and the food waste is excellent in crushing when stirred. It should be noted that the apparent density is calculated by dividing the weight of the carrier by the volume. Specifically, for the numerical range of the above apparent density, for example, 300 kg / m 3 、350kg / m 3 , 400kg / m 3 and 450kg / m 3 Any one of the group consisting of is taken as the lower limit, and 950 kg / m 3 , 900kg / m 3 , 800kg / m 3 and 750kg / m 3 The range in which any one of the composed groups is used as the upper limit value.

[0060] [Independent bubble rate]

[0061] The independent bubble ratio of the carrier is preferably 50% or less, more preferably 0 to 40%, further preferably 0 to 20%, and most preferably 5 to 15%. The carrier has a bubble structure with an independent bubble ratio within the above range, so that microorganisms can easily penetrate into the interior of the carrier and the microorganisms can be more easily fixed to the carrier.

[0062] Therefore, the carrier has the above-mentioned specific apparent density and independent bubble rate, thereby forming interconnected pores for loading microorganisms, and the liquid added with microorganisms is impregnated into the carrier, so that the microorganisms are fixed in the pores. Then, a plurality of carriers and food waste are put into a treatment device with a stirring function and stirred, thereby promoting the decomposition of food waste. Specifically, for the numerical range of the above-mentioned independent bubble rate, for example, a range can be cited with any one of the group consisting of 0% and 5% as the lower limit value and any one of the group consisting of 50%, 40%, 20% and 15% as the upper limit value.

[0063] The closed cell ratio of the carrier can be measured according to Procedure C of ASTM-D2856-70 using an air comparison densitometer Model 930 manufactured by Toshiba Beckman Corporation.

[0064] [C-type durometer hardness of carrier cross section]

[0065] The C-type durometer hardness (average hardness) of the cross section of the carrier is preferably 80 to 100, more preferably 85 to 98, and most preferably 86 to 96. When the cross section of the carrier has the above hardness, the crushability of the food waste is excellent. In particular, the surface hardness of the carrier can be adjusted to the above range by adjusting the hardness of the base resin itself constituting the carrier and the apparent density of the carrier. From the above viewpoint, the base resin used is preferably thermoplastic starch or aliphatic polyester, more preferably starch polyester resin, polylactic acid resin. Specifically, for the numerical range of the aforementioned C-type durometer hardness, for example, a range with any one of the group consisting of 80, 85 and 86 as the lower limit and any one of the group consisting of 100, 98 and 96 as the upper limit can be cited.

[0066] The carrier of the present invention is manufactured by extrusion molding based on an extruder. For example, the molten material obtained by heating and melting the substrate resin is extruded from a mold (a mold corresponding to the desired cross-sectional shape) arranged at the front end of the extruder (single-screw extruder) and foamed. It should be noted that the physical foaming agent is pressed into the molten material, and the chemical foaming agent is heated and melted together with the substrate resin. Then, the extruded and foamed molded body (rope-like strand) is fully cooled in a water tank, sheared with a cutting device (granulator), and the length is adjusted, thereby obtaining a columnar carrier.

[0067] It should be noted that the carrier is preferably formed by cutting the above-mentioned strands to form columnar particles. In particular, when the strands are foamed, by cutting the foam, a bubble structure appears on its cut surface. The cut surface has a concave-convex shape. Microorganisms are easily fixed on such concave-convex parts from the bubbles, and the decomposability of the carrier for food waste is further improved. From the above viewpoint, the apparent density of the carrier is preferably 350 to 800 kg / m 3 The above apparent density is achieved by forming a bubble structure.

[0068] As the blowing agent, there is no particular limitation, for example, inorganic physical blowing agents such as air, nitrogen, carbon dioxide, argon, helium, oxygen, neon, etc.; aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, etc.; alicyclic hydrocarbons such as cyclohexane and cyclopentane; halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, methyl chloride, ethyl chloride, methylene chloride, etc.; organic physical blowing agents such as dialkyl ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, etc. These are used alone or in combination of two or more. Among the above, nitrogen, air, and carbon dioxide are more preferred from the environmental aspect, and carbon dioxide is particularly preferred.

[0069] When an inorganic physical foaming agent is used, the amount of the foaming agent added is preferably 0.5 to 30 parts by mass relative to 100 parts by mass of the base resin. When an organic physical foaming agent is used, the amount of the foaming agent added is preferably 5 to 50 parts by mass relative to 100 parts by mass of the base resin.

[0070] The cell nucleating agent is not particularly limited, and inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, alumina, bentonite, and diatomaceous earth can be used. Among these, talc is preferred because the cell diameter can be easily adjusted.

[0071] The amount of the cell nucleating agent added is preferably 0.1 to 7 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.3 to 3 parts by mass, relative to 100 parts by mass of the base resin.

[0072] Example

[0073] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the description of the examples.

[0074] In Examples 1 to 7 and Comparative Examples 1 and 2, carriers having a star-shaped cross-sectional shape were produced using the formulations shown in Table 1.

[0075] Table 1

[0076]

[0077] The details of each component in Table 1 are as follows.

[0078] (1) PLA (polylactic acid): "LX975 (amorphous PLA, D-type content 12%, plant-based content 99.9%, manufactured by Total Corbivir A / S)".

[0079] (2) Starch polyester resin: "Mater-Bi (100% plant-based content, manufactured by Novamont company)".

[0080] ※Starch polyester resin is a resin mixed with thermoplastic starch and PBAT (100% plant-based content). The amount of thermoplastic starch added is about 30% by mass when the total of thermoplastic starch and PBAT is 100% by mass.

[0081] (3) PBS (polybutylene succinate): "FZ91PB (plant-based content 48.5%, manufactured by Mitsubishi Chemical Corporation)".

[0082] ※For the plant-based content of PLA and PBS, please refer to the BiomassPlaPL list of the Japan Bioplastics Association.

[0083] (4) PP (polypropylene): "J-750HP (b-pp, petroleum-based thermoplastic resin, manufactured by Prime Polymer Co., Ltd.)".

[0084] (5) PVA (polyvinyl alcohol): "Poval C-500T (density 1.3 g / cm 3 (Made by Kuraray Co., Ltd.))".

[0085] (6) Cell nucleating agent: "Talc (Hi-Filler 5000PJ, manufactured by Matsumura Industries)".

[0086] (7) Physical foaming agent: "Carbon dioxide (physical foaming agent)".

[0087] (8) Chemical foaming agent: "PO217K (citric acid sodium bicarbonate system, manufactured by Dainichi Seika Co., Ltd.)".

[0088] PLA, starch polyester resin, PBS, and PVA are biodegradable resins (biodegradability is 60% or more), and PP is a non-biodegradable resin (biodegradability is less than 60%).

[0089] The carriers in Examples 1 to 7 and Comparative Examples 1 and 2 are obtained by heating and melting the base resin and the bubble nucleating agent, and then extruding and foaming the melt from a star-shaped die provided at the front end of an extruder (machine No. 1: φ50mm, L / D=50, single-screw extruder). Next, the extruded and foamed molded body (strand) is fully cooled in a 4m water tank, and then sheared with a granulator (large fan-type cutter: manufactured by Star Plastics Co., Ltd.) to obtain a carrier. It should be noted that the physical foaming agent is injected into the melt, and the chemical foaming agent is heated and melted together with the base resin. The bubble nucleating agent, physical foaming agent, and chemical foaming agent in Table 1 are the amounts added when the base resin composed of each resin is set to 100% by weight.

[0090] The apparent density, closed cell ratio, average particle size, arithmetic mean height (Sa), weight loss rate, and household waste decomposition test were determined for the carriers of Examples 1 to 7 and Comparative Examples 1 and 2. The results are shown in Table 2.

[0091] Table 2

[0092]

[0093] [Biodegradability]

[0094] The biodegradability of the carrier can be measured based on the general method of JIS K6953 (equivalent to the method of JIS K6953-1), and is a value calculated by [(total CO2 generation during storage for 90 days in a composting environment) / (theoretical carbon dioxide generation calculated from the composition formula)]×100. For the carriers of Examples 1 to 7 and Comparative Example 2, the biodegradability measured by the above method was 60% or more, and for the carrier of Comparative Example 1, it was 0%.

[0095] [Apparent density]

[0096] The apparent density is calculated by dividing the weight of the carrier by the volume determined by sinking the carrier into a graduated container filled with water and measuring the rise in the water level (water level method).

[0097] [Independent bubble rate]

[0098] The closed cell ratio S (%) was calculated from the true volume Vx of the carrier measured using an air comparison densitometer (Model 930 manufactured by Toshiba Beckman Co., Ltd.) according to Step C described in STM D2856-70, and was determined as the average value of N=3 using the following formula (1).

[0099] S(%)=(Vx-W / ρ)×100 / (VA-W / ρ) (1)

[0100] Vx: True volume of the sample determined by the above method (cm3 ) (equivalent to the sum of the volume of the resin of the sample constituting the carrier and the total volume of the bubbles in the closed bubble part in the sample).

[0101] VA: Apparent volume (cm2) obtained by dividing the weight of the sample used in the measurement by the apparent density of the sample used in the measurement. 3 ).

[0102] W: total weight of the sample used in the measurement (g).

[0103] ρ: Density of the resin constituting the carrier (g / cm 3 ).

[0104] [Average particle size]

[0105] The average particle size is obtained by measuring the maximum height of each columnar carrier with a vernier caliper or the like and calculating the average value (N=3).

[0106] [Arithmetic mean altitude (Sa)]

[0107] The arithmetic mean height (Sa) was determined based on a three-dimensional image of the carrier side taken by a digital microscope VHX-7000 (non-contact) and using analysis software (VHX-H5M). It should be noted that the three-dimensional image used was an image after the shape was flattened using an L-filter (cutoff value: 0.25 mm).

[0108] [Weight reduction rate]

[0109] 3 ml of each carrier and a test piece (NEOMA FOAM, manufactured by Asahi Kasei Corporation) of 10 mm square and 60 mm long as the crushing object were placed in a sample bottle with a diameter of φ40 mm and a height of 120 mm containing 35 ml of water together with a stirring bar. A stirring test was carried out using a magnetic stirring bar at a stirring speed of 1000 rpm. The test piece was taken out from the sample bottle every hour, and the weight was measured after being fully dried. The weight reduction rate W (%) was calculated using the following formula (2) for evaluation.

[0110] W(%)=(wb-wa)×100 / (wa) (2)

[0111] In the above formula (2), wa and wb are respectively as follows.

[0112] wa: weight of the test piece before the test (g).

[0113] wb: weight of the test piece 1 hour after the start of the test (g).

[0114] The number of experiments was set to n=3.

[0115] [Decomposition test of domestic waste]

[0116] In the test of decomposition of domestic waste, a domestic waste disposer SINKPIA GJ-20 (manufactured by SINKPIA JAPAN) was used. A carrier (20 L) on which microorganisms were fixed and four equal parts of cabbage (2.5 kg) were placed in the disposer. After stirring in the disposer for 2 days, the weight of the cabbage residue in the disposer was measured, and the decomposition performance of the domestic waste was evaluated based on the value of the decomposition rate C (%) calculated by the following formula (3).

[0117] C(%)=(A-B)×100 / (A) (3)

[0118] A and B in the above formula (3) are as follows.

[0119] A: Weight of cabbage before the experiment (g).

[0120] B: Cabbage residue (g) in the processor 48 hours after the start of the test.

[0121] The evaluation criteria for the decomposition performance of household waste are as follows.

[0122] When the decomposition rate of the cabbage calculated by the above formula (3) 2 days after the start of the test was 80% or more and the core of the cabbage did not remain: ◎.

[0123] The decomposition rate of the cabbage calculated by the above formula (3) 2 days after the start of the test was 80% or more, but there was a part of the cabbage core remaining: 0.

[0124] When the decomposition rate of the cabbage calculated by the above formula (3) 2 days after the start of the test is less than 80%: x.

[0125] [C-type durometer hardness of carrier cross section]

[0126] The C-type durometer hardness of the carrier cross section refers to the hardness measured using a C-type durometer (ASKER C-type durometer) based on JIS K7312 (1996), and is a value obtained by measuring the cell membrane portion of the carrier cross section.

[0127] [Surface state of the side portion of the carrier]

[0128] An electron microscope photograph (10,000 times) was taken of the surface of the side surface of the columnar carrier. 2 The number of pores with a maximum diameter of 0.3 to 3 μm in the area. In Examples 4 to 6, where starch polyester was used as the base resin, the diameter of the pores was confirmed. In Example 4, the number was 42 / 100 μm. 2, in Example 5, 58 pieces / 100 μm 2 , in Example 6, 42 pieces / 100 μm 2 .

[0129] In Examples 1 to 7, the biodegradability was 60% or more, and thus the biodegradability was achieved. On the other hand, in Comparative Example 1, the biodegradability was 0%, and thus the biodegradability of the carrier was poor. In Comparative Example 2, since neither the thermoplastic starch nor the aliphatic polyester was included in the base resin, the carrier was dissolved by the moisture contained in the domestic waste or the water generated when the domestic waste was decomposed, and the decomposition performance of the food waste was not exerted.

Claims

1. A microbial carrier for food waste treatment, wherein: The base resin constituting the microbial carrier comprises thermoplastic starch and / or aliphatic polyester. The biodegradability of the microbial carrier in a biodegradability test based on JIS K6953 is 60% or more. The microorganism carrier is in a columnar shape.

2. The microbial carrier for food waste treatment according to claim 1, wherein The arithmetic mean height Sa of the surface irregularities of the surface of the microorganism carrier is 2.4 μm or more.

3. The microbial carrier for food waste treatment according to claim 1 or 2, wherein: The apparent density of the microbial carrier is 400 kg / m 3 Above and 800kg / m 3 the following.

4. The microbial carrier for food waste treatment according to any one of claims 1 to 3, wherein The shape of the cross section when cut perpendicularly to the height direction of the microorganism carrier is a polygon.

5. The microbial carrier for food waste treatment according to any one of claims 1 to 4, wherein The plant-based content of the thermoplastic starch or aliphatic polyester based on ASTM D6866 is 40% or more.

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