Microbial carriers for food waste treatment

Abstract

To provide an organism carrier for food waste treatment which dispenses with treatment by incineration and landfill (or sufficiently reduces amount), and less influences the environment.SOLUTION: A columnar organism carrier for food waste treatment contains thermoplastic starch and / or aliphatic polyester as a base material resin, and has a biodegradation degree in a biodegradable test according to JIS K 6953 of 60% or more.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a microbial carrier for food waste treatment, which carries microorganisms for treating food waste. [Background technology]

[0002] Most food waste is disposed of by incineration at incineration plants or landfill. Incineration releases large amounts of waste heat and carbon dioxide, raising concerns about its environmental impact. Furthermore, securing landfill sites is a challenge for landfill disposal.

[0003] Therefore, various technologies have been proposed for processing food waste other than incineration or landfill. For example, the technology of biodegrading food waste using microorganisms is attracting attention because it has a low environmental impact and does not require securing landfill land. Food waste is decomposed into water and carbon dioxide by microorganisms. The microorganisms are supported on a carrier, and this carrier is then used to dispose of the waste. By agitating the food waste together with the processing material, the food waste is decomposed.

[0004] For example, Patent Documents 1 and 2 disclose technologies relating to carriers for supporting microorganisms. The carrier in Patent Document 1 includes a thermoplastic resin, and the carrier in Patent Document 2 includes a polyolefin and a polystyrene. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-55562 [Patent Document 2] Patent No. 6869307 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Here, the carrier material needs to be replaced after a certain period, for example, about two years, due to decreased biodegradability and odor accumulation. As a result, the used carrier materials described in Patent Documents 1 and 2 become a large amount of waste, requiring disposal by incineration or landfill as described above. Therefore, there were problems with environmental impact and securing landfill space.

[0007] Considering the above circumstances, the present invention provides a food waste treatment method that eliminates the need for incineration or landfill treatment (or significantly reduces the amount thereof) and has minimal environmental impact. slight The purpose is to provide biological carriers. [Means for solving the problem]

[0008] [1] Thermoplastic starch and / or aliphatic polyester as the base resin, based on JIS K6953 A columnar food waste treatment material that has a biodegradability of 60% or more in biodegradation tests. slight A biological carrier.

[0009] [2] The microorganisms Hold The arithmetic mean height (Sa) of surface irregularities on the body surface is 2.4 μm or greater. 5μm or less The microbial carrier for food waste treatment described in [1].

[0010] [3] The aforementioned microorganism Hold The apparent density of the body is 400 kg / m³. 3 More than 800kg / m 3 The following microbial carriers for food waste treatment described in [1] or [2]:

[0011] [4 ]before microbial carrier Hold A microbial carrier for food waste treatment described in any of [1] to [3], wherein the cross-sectional shape when cut perpendicular to the height direction of the body is polygonal.

[0012] The microbial carrier for food waste treatment according to any one of [1] to [4], wherein the plant degree of the thermoplastic starch or aliphatic polyester based on ASTM D6866 is 40% or more.

Advantages of the Invention

[0013] The microbial carrier for food waste treatment of the present invention is biodegradable. Therefore, treatment by incineration or landfill is unnecessary (or the amount is sufficiently reduced), and the environmental impact can also be reduced.

Brief Description of the Drawings

[0014] [Figure 1] It is a perspective view of a carrier according to an example of the present invention. [Figure 2] It is a perspective view of a carrier according to an example of the present invention. [Figure 3] It is a perspective view of a carrier according to an example of the present invention. [Figure 4] It is a perspective view of a carrier according to an example of the present invention. [Figure 5] It is a perspective view of a carrier according to an example of the present invention. [Figure 6] It is a perspective view of a carrier according to an example of the present invention. [Figure 7] It is a perspective view of a carrier according to an example of the present invention. [Figure 8] It is an electron micrograph (10,000 times) of the surface of the side portion of a carrier according to an example of the present invention.

Modes for Carrying Out the Invention

[0015] The microbial carrier for food waste treatment according to the present invention slight (hereinafter simply referred to as "carrier") is a structure that carries microorganisms for treating food waste. Food waste includes residues generated during the cooking process of food, leftovers generated during the distribution process of food, and uneaten portions generated during the consumption stage of food.

[0016] In the present invention, food waste is crushed by the support. Simultaneously with the crushing in the processing device, the food waste is decomposed into water and carbon dioxide by microorganisms and discharged. As described above, the support has the function of supporting microorganisms and the function of crushing food waste.

[0017] Specifically, the carrier of the present invention exhibits a biodegradability of 60% or more, preferably 80% or more, and more preferably 90% or more, in the biodegradability test of JIS K6953. In other words, the carrier of the present invention is biodegradable by microorganisms. Therefore, there is no need to incinerate or landfill the carrier after use (or the amount of material that needs to be disposed of in such ways is significantly reduced).

[0018] The biodegradability test specified in JIS K6953 is a test in which a sample (a carrier in this invention) is placed in aerobic compost (compost with good aeration) and the degree of biodegradation is calculated from the amount of carbon dioxide produced when it is decomposed by microorganisms.

[0019] The support material of the present invention uses thermoplastic starch and / or aliphatic polyester as the base resin.

[0020] Thermoplastic starch is a modified starch obtained by giving starch or a starch derivative thermoplastic properties. Examples of thermoplastic starch include those in which some of the three hydroxyl groups of glucose, a constituent unit of the starch molecular chain, are converted into hydrophobic groups through etherification or esterification reactions, and plasticizers such as glycerin or ethylene glycol are added.

[0021] The thermoplastic starch content in the base resin is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0022] Aliphatic polyesters contain aliphatic esters as the main component in their main chain. The content of aliphatic esters in the main chain is at least 60 mol%, preferably 80-100 mol%, and more preferably 90-100 mol%. Aliphatic polyester resins include hydroxy acid polycondensates, lactone ring-opening polymers, and polycondensates of polyhydric alcohol components and polyhydric carboxylic acid components. Examples of hydroxy acid polycondensates include polylactic acid and polycondensates of hydroxybutyric acid. Examples of lactone ring-opening polymers include polycaprolactone and polypropiolactone. Examples of polycondensates of polyhydric alcohol components and polyhydric carboxylic acid components include polybutylene succinate (PBS), polybutylene adipate (PBAT), and polyethylene succinate. Among these, polylactic acid and polybutylene succinate are preferred from the viewpoint of moldability of the support.

[0023] The aliphatic polyester content 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.

[0024] Furthermore, the thermoplastic starch and aliphatic polyester used as the base resin preferably have a biodegradability of 60% or more, more preferably 80% or more, and even more preferably 90% or more, according to JIS K6953.

[0025] The plant-derived content of at least one of the thermoplastic starch and aliphatic polyester is preferably 20% or more, more preferably 50% or more, and even more preferably 70% or more. By setting the plant-derived content of the thermoplastic starch and aliphatic polyester within the above range, it is possible to improve the carbon neutrality effect and suppress global warming. The plant-derived content can be measured according to ASTM D6866.

[0026] Furthermore, it is preferable that at least one of the thermoplastic starch and aliphatic polyester has a marine biodegradability of 90% or more. By using such a base resin, if the carrier is damaged during waste treatment, it can be quickly decomposed even if it flows into rivers or the sea with the wastewater. The marine biodegradability can be measured according to ASTM D6691.

[0027] The content of 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. Note that the content of thermoplastic starch and / or aliphatic polyester in the base resin refers to the total amount if both thermoplastic starch and aliphatic polyester are present in the base resin.

[0028] The base resin of the support according to the present invention may contain other resins besides thermoplastic starch and aliphatic polyester, within a range that maintains a biodegradability of 60% or more of the support. Other resins may include, for example, polypropylene resins, polyester resins, polyolefin resins, polyphenylene ether resins, and other polymers such as 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, even more preferably 3% by mass or less, and most preferably 0 (i.e., the base resin contains only thermoplastic starch and / or aliphatic polyester).

[0029] The carrier may contain various other components, provided that the biodegradability of the carrier is maintained at 60% or higher. Examples of other components include various additives such as blowing agents (physical and chemical blowing agents), foam regulators, plasticizers, pigments, dyes and other colorants, heat stabilizers, and fillers.

[0030] The structural characteristics of the carrier are as follows:

[0031] [shape] Figures 1 to 7 are perspective views of the carrier. As illustrated in Figures 1 to 7, the carrier of the present invention is columnar. Preferably, the carrier is a structure that includes a bottom surface, a top surface, and side surfaces located between the bottom surface and the top surface.

[0032] The cross-sectional area of ​​the carrier (i.e., the area of ​​the base and top surface) is, for example, 0.5 to 1.4 cm². 2 It is a columnar shape with a height of 0.8 to 1.3 cm. The cross-sectional area is the area of ​​the cross-section when the carrier is cut by a plane perpendicular to the height direction x (axial direction).

[0033] Figure 1 shows a carrier with a circular cross-section. On the other hand, Figures 2 to 7 show carriers with polygonal cross-sections. Specifically, the cross-section of Figure 2 is triangular, the cross-section of Figure 3 is quadrilateral, the cross-section of Figure 3 is pentagonal, the cross-section of Figure 4 is hexagonal, the cross-section of Figure 6 is cross-shaped (a shape in which the centroids of two rectangles intersect and are perpendicular), and the cross-section of Figure 7 is star-shaped. However, the cross-sectional shape of the carrier is not limited to the examples above. Note that the cross-sectional shape is the shape of the cross-section when the carrier is cut by a plane perpendicular to the height direction x.

[0034] When the volume is the same, a carrier with a polygonal cross-section has a larger surface area compared to a carrier with a circular cross-section, making it easier for microorganisms to colonize, and the corners improve crushability, thus improving the decomposition efficiency of food waste. Therefore, a polygonal cross-section is preferred for the carrier, and a star shape is more preferred among polygons. However, carriers with a circular cross-section are also included in this invention.

[0035] [Average particle size] The average particle diameter is preferably 5 to 20 mm, more preferably 6 to 15 mm, and even more preferably 7 to 13 mm. Handling is excellent when the average particle diameter is within the above range. The average bubble diameter can be determined by measuring the average of the maximum heights of the columnar carriers using a caliper or similar device. The volume per carrier is 0.2 to 1 cm³. 3Preferably, it is 0.3 to 0.8 cm. 3 It is more preferable that the volume per carrier is within the above range. If the volume per carrier is within the above range, the carrier will have excellent decomposition performance. The volume per carrier can be calculated from the apparent density of the carrier and the weight per carrier, which are measured separately.

[0036] Furthermore, the ratio (L / d) of the average particle diameter of the support to the maximum length in the cross-section of the support is preferably 1 to 2, and more preferably 1.0 to 1.6. If (L / d) is within the above range, the material will have excellent fluidity within the waste treatment device.

[0037] [Arithmetic mean height (Sa)] The arithmetic mean height (Sa) of the surface irregularities on the surface of the carrier is preferably 2.4 to 5 μm, more preferably 2.5 to 4.5 μm, and even more preferably 3.0 to 4.2 μm. The arithmetic mean height is an index that indicates the average value of the height difference from the average plane. If the arithmetic mean height (Sa) is within the above range, the surface irregularities are thought to provide resistance when in contact with food waste, resulting in superior crushing power. With the above structure, an irregular structure is formed on the entire surface of the carrier, resulting in superior crushing performance for food waste.

[0038] In this invention, the arithmetic mean height is determined by measuring the surface of a columnar carrier using any known method. For example, the arithmetic mean height is determined using analysis software from a 3D image of the side surface of the carrier, which is captured using a laser microscope. The 3D image used is one in which the shape has been flattened by applying an L-filter (a filter that removes long wavelengths such as waviness and shape components).

[0039] In addition, it is preferable that pores with a size of about 0.3 to 3 μm are formed on the surface of the side portion of the columnar carrier as shown in FIG. 8. When pores as described above are formed and the carrier is a porous body, the adsorptivity of microorganisms is particularly excellent. From the above viewpoints, the maximum diameter of the pores is preferably 0.3 to 3 μm, and more preferably 0.5 to 2 μm. The maximum diameter of the pores on the surface of the carrier means the absolute maximum length.

[0040] In addition, in the electron micrograph of the surface of the side portion of the columnar carrier, within an area of 100 μm 2 it is preferable that 5 to 80 pores with a maximum diameter of 0.3 to 3 μm are formed. The number of pores is preferably 10 to 40 pores / 100 μm 2 . The formation of pores as described above can be achieved, for example, by using a base resin containing thermoplastic starch.

[0041] [Apparent density] The apparent density of the carrier is preferably 300 to 950 kg / m 3 and more preferably 350 to 900 kg / m 3 and even more preferably 400 to 800 kg / m 3 . Within the above range, the carrier has an appropriate weight and is excellent in the pulverizability of food waste during stirring. The apparent density is calculated by dividing the weight of the carrier by the volume.

[0042] [Closed cell ratio] The closed cell ratio of the carrier is preferably 50% or less, more preferably 0 to 40%, and even more preferably 0 to 20%. When the carrier has a cell structure with a closed cell ratio within the above range, microorganisms can easily penetrate to the inside of the carrier, and a large number of microorganisms can easily adhere to the carrier. Therefore, because the carrier has the above-mentioned specific apparent density and closed-cell ratio, interconnected pores for supporting microorganisms are formed, and by impregnating the carrier with a liquid to which microorganisms have been added, the microorganisms are fixed to the pores. Then, by introducing multiple carriers and food waste into a processing device equipped with a stirring function and stirring, the decomposition of the food waste is promoted.

[0043] The closed-cell ratio of the carrier can be measured using a Toshiba Beckman Corporation Model 930 air-comparative hydrometer, according to procedure C of ASTM-D2856-70.

[0044] [Type C durometer hardness of the carrier cross-section] The Type C durometer hardness (average hardness) of the cross-section of the carrier is preferably 80 to 100, and more preferably 85 to 98. When the cross-section of the carrier has the above hardness, it exhibits excellent crushing properties for food waste. In particular, the surface hardness of the carrier can be adjusted to the above range by adjusting the hardness of the base resin 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, and more preferably starch polyester resin or polylactic acid resin.

[0045] The carrier of the present invention is manufactured by extrusion molding using an extruder. For example, a molten material obtained by heating and melting a base resin is extruded and foamed through a die (a die corresponding to the desired cross-sectional shape) installed at the tip of an extruder (single extruder). A physical foaming agent is injected into the molten material under pressure, and a chemical foaming agent is heated and melted together with the base resin. After the extruded and foamed molded body (string-like strand) is sufficiently cooled in a water tank, it is cut with a cutting device (pelletizer) to adjust the length, thereby obtaining a columnar carrier.

[0046] Furthermore, it is preferable that the carrier is formed by cutting the strands into columnar particles. In particular, when the strands are foam, cutting the foam creates a cut surface, and the cellular structure appears on the cut surface, creating irregularities. Microorganisms can easily colonize these irregularities derived from the cellular structure, resulting in even better decomposition of food waste. From the above viewpoint, the apparent density of the carrier derived from the cellular structure is 350 to 800 kg / m³. 3 It is preferable that this be the case.

[0047] The blowing agent is not particularly limited and includes, for example, inorganic physical blowing agents such as air, nitrogen, carbon dioxide, argon, helium, oxygen, and neon; aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and n-hexane; 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, and methylene chloride; and organic physical blowing agents such as dimethyl ether, diethyl ether, and methyl ethyl ether. These are used alone or in combination of two or more. Among these, nitrogen, air, and carbon dioxide are more preferred from an environmental perspective, and carbon dioxide is particularly preferred.

[0048] When using an inorganic physical blowing agent, the amount of blowing agent added is preferably 0.5 to 30 parts by mass per 100 parts by mass of the base resin, and when using an organic physical blowing agent, the amount is preferably 5 to 50 parts by mass per 100 parts by mass of the base resin.

[0049] While not particularly limited, inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium dioxide, clay, aluminum oxide, bentonite, and diatomaceous earth can be used as bubble regulators. Among these, talc is preferred because it allows for easy adjustment of bubble diameter.

[0050] The amount of foam regulator 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, per 100 parts by mass of the base resin. [Examples]

[0051] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples described.

[0052] For Examples 1-7 and Comparative Examples 1 and 2, a support with a star-shaped cross-section was manufactured using the formulations shown in Table 1.

[0053] [Table 1]

[0054] The details of each component in Table 1 are as follows: (1) PLA (Polylactic Acid): "LX975 (Amorphous PLA, D-isomer content 12%, plant-derived 99.9%, manufactured by TotalCorbion)" (2) Starch polyester resin: "Matarbee (100% plant-based, manufactured by Novamont)" (3) *Starch polyester resin is a resin made by mixing thermoplastic starch and PBAT (100% plant-derived). The amount of thermoplastic starch added is approximately 30%. (4) PBS (Polybutylene succinate): "FZ91PB (48.5% plant-derived, manufactured by Mitsubishi Chemical)" *The plant-derived content of PLA and PBS was referenced from the Japan Bioplastics Association's Biomass Plastics PL List. (5) PP (Polypropylene): "J-750HP (b-pp, petroleum-based thermoplastic resin, manufactured by Prime Polymer)" (6) PVA (Polyvinyl Alcohol): "Product name: Poval C-500T (Density 1.3 g / cm³)" 3 (Manufactured by Kuraray) (7) Bubble regulator: "Talc (Hi-Filler 5000PJ, manufactured by Matsumura Sangyo)" (8) Physical blowing agent: "Carbon dioxide (physical blowing agent)" (9) Chemical blowing agent: "PO217K (sodium bicarbonate citrate-based, manufactured by Dainichi Seika)"

[0055] The carriers in Examples 1-7 and Comparative Examples 1 and 2 were obtained by heating and melting a base resin and a foam regulator, and then extruding the resulting molten material through a star-shaped die installed at the tip of an extruder (Machine No. 1: φ50 mm, L / D=50, single extruder) to produce foam. Next, the extruded and foamed molded body (strand) was thoroughly cooled in a 4 m water tank, and then cut with a pelletizer (large fan cutter: made of star-shaped plastic) to obtain the carrier. The physical foaming agent was injected into the molten material, and the chemical foaming agent was heated and melted together with the base resin.

[0056] For the carriers of Examples 1-7 and Comparative Examples 1 and 2, the degree of biodegradation, apparent density, closed-cell ratio, average particle size, arithmetic mean height (Sa), weight loss rate, and food waste decomposition test were identified. The results are shown in Table 2.

[0057] [Table 2]

[0058] [Biodegradability] The biodegradability of the carrier can be measured according to JIS K6953, and is calculated as [(total CO2 generation during 90 days of storage in a composting environment) / (theoretical carbon dioxide generation calculated from the composition formula)] × 100.

[0059] [Apparent density] The apparent density was calculated by dividing the weight of the carrier by the volume obtained by measuring the rise in water level in a water-filled container with a graduated line (submersion method).

[0060] [Closed cell ratio] The closed-cell ratio S(%) was calculated from the true volume Vx of the carrier, measured using an air-comparison hydrometer (Toshiba Beckmann, Model 930), in accordance with Procedure C described in STM D2856-70, using the following equation (1), and the average value for N=3 was obtained. S(%)=(Vx-W / ρ)×100 / (VA-W / ρ)···(1) Vx: True volume of the sample measured by the above method (cm³) 3 (This corresponds to the sum of the volume of the resin constituting the sample in the carrier and the total volume of the closed-cell portions within the sample.) VA: Apparent volume (cm³) obtained by dividing the weight of the sample used in the measurement by the apparent density of the sample used in the measurement. 3 ) W: Total weight of the sample used for measurement (g) ρ: Density of the resin constituting the carrier (g / cm³) 3 )

[0061] [Average particle size] The average particle diameter was calculated by measuring the maximum height of each individual columnar carrier using a caliper or similar tool, and then averaging the results (N=3).

[0062] [Arithmetic mean height (Sa)] The arithmetic mean height (Sa) was determined using analysis software (VHX-H5M) on 3D images of the side surface of the carrier, captured with a digital microscope VHX-7000 (non-contact type). The 3D images were flattened by applying an L-filter (cutoff value: 0.25 mm).

[0063] [Weight reduction rate] 3 ml of each carrier and a 10 mm square, 60 mm long test piece (Neomafoam, manufactured by Asahi Kasei) to be crushed were placed together with a stirring bar in a sample bottle with a diameter of φ40 mm and a height of 120 mm containing 35 ml of water. A stirring test was performed using a magnetic stirrer at a stirring speed of 1,000 rpm. Every hour, the test piece was removed from the sample bottle, thoroughly dried, and its weight was measured. The weight loss rate, W(%), calculated from the following formula (2), was used for evaluation. W(%)=(wb-wa)×100 / (wa)···(2) However, wa and wb in equation (2) above are as follows: wa: Weight of the test specimen before the start of the test (g) wb: Weight of the test specimen (g) 1 hour after the start of the test The number of tests was set to n=3.

[0064] [Food waste decomposition test] The food waste decomposition test was conducted using a SINKPIA GJ-20 food waste processor (manufactured by SINKPIA Japan). A carrier body (20L) containing established microorganisms and a cabbage cut into four equal parts (2.5kg) were placed inside the processor. After stirring in the processor for two days, the weight of the cabbage residue inside the processor was measured, and the decomposition performance of the food waste was evaluated based on the decomposition rate: C(%) calculated using the following formula (3). C(%) = (AB) × 100 / (A) ... (3) However, A and B in equation (2) above are as follows: A: Cabbage weight (g) before the start of the test B: Cabbage residue in the processing machine 48 hours after the start of the test (g)

[0065] The evaluation criteria for food waste decomposition performance are as follows: If the decomposition rate of the cabbage after 2 days from the start of the test, calculated using formula (3) above, is 80% or more, and no core remains of the cabbage...◎ If the decomposition rate of the cabbage after 2 days from the start of the test, calculated from formula (3) above, is 80% or more, but some of the cabbage core remains... ○ If the cabbage decomposition rate calculated from formula (3) above, two days after the start of the test, is 80% or less... ×

[0066] [Type C durometer hardness of the carrier cross-section] The Type C durometer hardness of the support cross-section refers to the hardness measured using a Type C durometer (Asker Type C hardness tester) based on JIS K7312 (1996), and is the value measured in the cellular film portion of the support cross-section.

[0067] [Surface condition of the side portion of the carrier] An electron microscope image (10,000x magnification) was taken of the surface of the side portion of the columnar carrier. In the obtained image, 100 μm 2The number of pores with a maximum diameter of 0.3 to 3 μm within the area was measured. In Examples 4 to 6, which used starch polyester as the base resin, the pore diameter characteristics were confirmed. In Example 4, there were 42 pores / 100 μm. 2 In Example 5, there were 58 particles per 100 μm. 2 In Example 6, there were 42 particles / 100 μm 2 That was the case.

[0068] In Examples 1-7, the biodegradability was 60% or higher, indicating that biodegradation was possible. On the other hand, in Comparative Example 1, the biodegradability was 0%, indicating that the biodegradability of the carrier was inferior. Furthermore, in Comparative Example 2, the carrier dissolved due to the moisture contained in the food waste and the water generated during the decomposition of the food waste, and was unable to exhibit its ability to decompose food waste.

Claims

1. A columnar microbial carrier for food waste treatment, having a base resin of thermoplastic starch and / or aliphatic polyester, and exhibiting a biodegradability of 60% or more in a biodegradability test based on JIS K6953.

2. The microbial carrier for food waste treatment according to claim 1, wherein the arithmetic mean height (Sa) of the surface irregularities on the surface of the microbial carrier is 2.4 μm or more and 5 μm or less.

3. The apparent density of the microbial carrier is 400 kg / m³ ３ More than 800kg / m ３ The following is a microbial carrier for food waste treatment according to claim 1 or 2.

4. The microbial carrier for food waste treatment according to claim 1 or 2, wherein the cross-sectional shape when the microbial carrier is cut perpendicular to the height direction is polygonal.

5. The microbial carrier for food waste treatment according to claim 1 or 2, wherein the thermoplastic starch or aliphatic polyester has a plant-derived content of 40% or more according to ASTM D6866.

Images