JP6885154B2 - Microbial immobilization carrier for wastewater treatment and wastewater treatment method - Google Patents

Description

The present invention relates to a microbial immobilization carrier for wastewater treatment used in anaerobic treatment.

There are known methods for biochemically treating domestic wastewater and factory wastewater using microorganisms. Aerobic treatment, which is performed by aerating a large amount of air and oxygen, and anaerobic treatment without aeration of air, etc. It is roughly divided into anaerobic treatment to be performed. Anaerobic treatment has advantages such as less excess sludge generation than aerobic treatment and less power because it does not require oxygen supply, and is expected to become more widespread in the future.

As a method of anaerobic treatment, an upward flow anaerobic sludge bed method (UASB) or an expanded sludge bed method (EGSB) using a granule, or an anaerobic microorganism on a membrane or a carrier is used by a method such as retention of anaerobic microorganisms. There are an anaerobic fixed bed method and an anaerobic fluid bed method using a biofilm in which the organism is immobilized.

In addition, the microbial immobilization method that purifies wastewater by immobilizing microorganisms that efficiently purify wastewater on the surface of inorganic or organic matter can increase the concentration of microorganisms in wastewater and improve the efficiency of wastewater purification. However, there is an advantage that the septic tank can be miniaturized.

The fluidized bed method, in which a microbial-immobilized carrier is suspended and fluidized in wastewater to purify it, has been attracting attention in recent years because it not only has high purification efficiency but also can operate stably for a long period of time. Specifically, as the microbial immobilization carrier of the fluidized bed, a polyurethane foam (for example, see Patent Document 1), a polyolefin foam (for example, see Patent Documents 2 and 3), and a molded product (for example, see Patent Document 1) and a molded product (for example, see Patent Document 1). Patent Document 4), and a method using a gel cross-linked with PVA or PEG (see, for example, Patent Documents 5 and 6) are disclosed.

However, when the microbial-immobilized carrier normally used in a fluidized bed is used in an anaerobic treatment, methane gas, carbon dioxide gas and nitrogen gas generated by the metabolic action of anaerobic bacteria are present in the carrier, and the carrier floats and flows. There is a problem that a failure occurs and the treatment performance is remarkably lowered, and a microbial-immobilized carrier suitable for anaerobic treatment is desired.

Japanese Unexamined Patent Publication No. 2010-195981 Japanese Unexamined Patent Publication No. 10-257858 Japanese Unexamined Patent Publication No. 2006-263489 Japanese Unexamined Patent Publication No. 10-314780 Japanese Unexamined Patent Publication No. 2001-0895774 Japanese Unexamined Patent Publication No. 2004-275113

The microbial-immobilized carrier of the present invention is used in an anaerobic treatment, can suppress carrier floating due to gas generated by the metabolic action of microorganisms, and provides a carrier having high wastewater treatment capacity having both microbial adhesion and fluidity. There is.

The present inventors have arrived at the present invention as a result of repeated diligent studies to solve the above problems. That is, it contains a synthetic resin and an inorganic substance, and has a density of 1.0 to 1.10 g / cm ³ , an outer diameter (D) of 10 to 25 mm, a thickness (t) of 1 to 2 mm, and a length (L) of an outer diameter (L). It has a tubular shape 0.2 to 0.8 times that of D), and extends in the length direction of a plurality of tubes having a width (W) of 0.5 to 2 mm and a height (H) of 0.5 to 2 mm on the outside of the cylinder. Provided is a microbial immobilization carrier for wastewater treatment used in an anaerobic treatment, which is characterized by having ribs.

The microbial-immobilized carrier of the present invention is used in an anaerobic treatment, can suppress carrier floating due to gas generated by the metabolic action of microorganisms, and can provide a carrier having high wastewater treatment ability having both microbial adhesion and fluidity. .. Specifically, by setting the ratio of the outer diameter (D) to the length (L) of the carrier shape to 0.2 to 0.8, the formation of the microbial layer inside the carrier is restricted, and the inside of the carrier is the microbial layer. Suppresses blockage by. As a result, the metabolic gas existing in the microbial layer can be released into the wastewater, and the carrier floating can be suppressed, so that the fluidity in the anaerobic treatment tank can be ensured. Further, since the outer surface of the carrier has ribs extending in the length direction, the amount of microbial adhesion increases, and a carrier having high wastewater treatment capacity can be provided.

The microbial-immobilized carrier of the present invention contains a synthetic resin and an inorganic substance, has a density of 1.0 to 1.10 g / cm ³ , an outer diameter (D) of 10 to 25 mm, and a thickness (t) of 0.5 to 2 mm. The length (L) is 0.2 to 0.8 times the outer diameter (D), and a plurality of cylinders have a width (W) of 0.5 to 2 mm and a height (H) of 0. A microorganism-immobilized carrier for wastewater treatment, which has ribs extending in a length direction of 5 to 2 mm.

As the material of the carrier, it is preferable to combine a synthetic resin and an inorganic substance in terms of density, size, strength, flexibility, surface condition, moldability and the like. As the synthetic resin, a flexible and lightweight polyolefin-based thermoplastic resin such as polyethylene and polypropylene is preferable, and low-density polyethylene (LDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), and the like. Examples thereof include ethylene-α-olefin copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer. Two or more of these may be used.

The melt flow rate (MFR) of the synthetic resin is not particularly limited, but when used as a microbial-immobilized carrier, the preferable MFR differs depending on the carrier molding method, and when molding by injection molding or the like, the MFR is 1 to 1. 100 g / 10 min is preferable, and when molding by extrusion molding or the like, the MFR is 0.01 to 20 g / 10 min. Within this range, the moldability is improved in each molding method. MFR is measured by JIS K 7210-1999, for example, in the case of polyethylene, it is measured at 190 ° C. and a load of 2.16 kg.

As the inorganic substance, a substance having a density of 1.3 to 6.0 g / cm ³ is used, and is not particularly limited. For example, calcium carbonate, talc, barium sulfate, iron oxide, aluminum hydroxide, zeolite and the like can be mentioned, and they can be used alone or in combination of two or more. Since the density of the synthetic resin is 1.0 g / cm ³ or less, these inorganic substances are combined for the purposes of adjusting the density of the synthetic resin, roughening the surface of the carrier, and imparting hydrophilicity.

Since there is almost no difference in carrier performance depending on the material combination of the above synthetic resin and inorganic substance, the mixing ratio is adjusted so that the density and surface condition fall within the desired range. However, if the proportion of the inorganic substance is large, it is easily damaged, so that the mixing proportion within the above-mentioned specific gravity range is suitable from the viewpoint of strength.

Fillers, additives, processing aids, hydrophilic agents, colorants, etc. may be added as long as the effects of the present invention are not impaired, but when used as a microbial immobilization carrier for wastewater purification, It is desirable to use the minimum amount of food that has as little impact on the environment and organisms as possible.

Examples of such additives include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, lactone-based antioxidants, light-resistant stabilizers, antistatic agents, and the like. Examples of the processing aid include waxes, metal soaps, fatty acids such as stearic acid, lubricants such as fluorine compounds, and the like. Examples of the hydrophilizing agent include amphoteric surfactants, ionic surfactants, nonionic surfactants and the like.

The microbial immobilization carrier of the present invention has a density of 1.0 to 1.10 g / cm ³ . When a microbial-immobilized carrier is used for a fluidized bed, it is preferable that the density is higher than that of water because the contact with wastewater is reduced and the purification efficiency is lowered when the carrier floats on the water surface. On the other hand, when the density is made larger than 1.10, the initial carrier sedimentation property when the carrier is put into the treatment tank is good, but when the microbial layer is formed due to the adhesion of microorganisms, it remains sunk at the bottom of the treatment tank. , Liquidity deteriorates.

Therefore, the density of the microbial-immobilized carrier is preferably ^{1.0 to 1.10 g / cm 3} in order to allow the carrier to flow and circulate with stirring with less power.

The microbial-immobilized carrier of the present invention has a carrier outer diameter (D) of 10 to 25 mm. The smaller the size of the carrier, the larger the surface area, which is preferable from the viewpoint of microbial adhesion. However, since the outflow prevention screen is made smaller, problems such as clogging are likely to occur. Further, if it is too large, the fluidity deteriorates, so that the outer diameter (D) of the carrier is preferably 10 to 25 mm.

The microbial-immobilized carrier of the present invention has a carrier thickness (t) of 0.5 to 2 mm. If the thickness of the carrier is thinner than 0.5 mm, not only the strength of the carrier is lowered, but also the moldability is lowered. On the other hand, if the thickness of the carrier exceeds 2 mm, not only the cost of the material increases, but also the inner diameter of the carrier becomes small, and the inside of the carrier is easily closed due to the formation of the microbial layer. Therefore, the thickness (t) of the carrier is 0. .5-2 mm is preferable.

In the microorganism-immobilized carrier of the present invention, the length (L) of the carrier is 0.2 to 0.8 times the outer diameter (D). By adjusting the length of the carrier to this range, the formation of the microbial layer inside the carrier is restricted, and the inside of the carrier is prevented from being blocked by the microbial layer. This is preferable because the nitrogen gas existing in the microbial layer can be released into the waste water, the carrier floating can be suppressed, and the fluidity in the anaerobic treatment tank can be ensured.

In the microorganism-immobilized carrier of the present invention, the shape of the carrier is tubular. A cup-shaped shape in which one end face of the carrier is closed is not preferable because nitrogen gas generated by wastewater purification accumulates inside the carrier and the carrier easily floats, and a tubular shape with both ends open is preferable. .. In particular, a hollow cylindrical one is preferable because it is easy to manufacture.

The microbial-immobilized carrier of the present invention has a plurality of ribs extending in the length direction having a width (W) of 0.5 to 2 mm and a height (H) of 0.5 to 2 mm on the outside of the carrier. By providing such ribs, the surface area of the carrier can be expanded, so that not only the amount of microorganisms supported increases, but also when the carriers collide with each other in the treatment tank, the microbial layer adhering to the carriers is peeled off. Can be suppressed.

As the molding method of the microorganism-immobilized carrier of the present invention, one obtained by injection molding, extrusion molding, press molding or the like may be used as it is, or the carrier may be cut to a predetermined size, crushed, fused, bonded or the like. It may be used after secondary processing. In particular, extrusion molding with high productivity and continuous molding is preferable, and hollow cylindrical extrusion molding is particularly preferable.

The extruder used for extrusion molding is not particularly limited, but a normal single-screw extruder, twin-screw extruder or the like may be used.

Further, when molding the carrier, there is no limitation that the material is kneaded, but for example, the carrier may be molded using a twin-screw extruder in the same direction, a single-screw extruder or the like. Further, in this case, similarly to the kneading method described above, the method of supplying the material is not limited to any method, but in order to improve the supply and dispersibility of the material, it is preferable to supply the material in a masterbatch.

In order to introduce a plurality of ribs on the outside of the carrier, for example, a method of extrusion molding using a mold in which grooves are cut at regular intervals on the outer surface of the extrusion molding die may be used.

In order to form a hollow cylinder, for example, a mold for a hollow cylinder is attached to the tip of an extruder such as a hose, a pipe, a straw, etc., and the mold is extruded at a temperature equal to or higher than the melting point of the resin. The extruded molded product is cooled in a cooling water tank or the like, and cut into a predetermined size with an appropriate cutting machine (for example, a pelletizer for cutting pellets) to obtain a carrier. Further, it may be produced by continuously cutting and cooling with a cutting machine such as a continuous rotary cutter in an atmosphere sprayed with cooling water immediately after being extruded from the mold.

The temperature of extrusion molding should be 120 to 250 ° C., as long as the microbial-immobilized carrier can be molded, but if the molding temperature is too low, an extrusion load during molding is likely to be applied, resulting in a decrease in productivity and shape instability. The range is preferable, and the range of 150 to 180 ° C. is particularly preferable.

The microorganism-immobilized carrier of the present invention may be used by appropriately immobilizing microorganisms in an anaerobic atmosphere. For example, when it is used for purifying wastewater, microorganisms used for purifying wastewater are immobilized on the surface of a carrier. Further, depending on the properties and temperature of the wastewater to be purified, the structure of the septic tank, and the like, an appropriate amount of the microbial immobilization carrier may be put into the wastewater and used in contact with the wastewater.

As a method of using the microbial-immobilized carrier of the present invention, any method of a fixed bed method and a fluidized bed method can be used, but it is preferable to use the fluidized bed method because the inside of the microbial-immobilized carrier is less clogged. Examples of the method of flowing the microbial immobilization carrier of the present invention in the wastewater by the fluidized bed method include a method of stirring with a stirring blade attached to the tip of the motor, and a method of sucking and discharging a part of the wastewater with a pump to stir. A method of stirring the wastewater by aerating an appropriate gas, a method of providing a baffle plate in the drainage tank and allowing the drainage to flow between them to naturally agitate the wastewater. There are no particular restrictions in any direction. If the stirring is too weak, the microbial-immobilized carrier does not flow in the wastewater and the contact between the wastewater and the microorganisms is reduced, so that the purification efficiency is lowered. If the stirring is too strong, the microbial-immobilized carrier is immobilized on the surface of the microbial-immobilized carrier. Since microorganisms are peeled off, stirring with an appropriate strength (speed) is desirable. Further, it is desirable that the outlet of the purified wastewater has a partition having a mesh smaller than the outer diameter and length of the carrier in order to prevent the outflow of the microorganism-immobilized carrier of the present invention.

As a method for immobilizing microorganisms on the microorganism-immobilized carrier of the present invention, the carrier may be directly put into wastewater to immobilize the microorganisms naturally, but the present invention is carried out in a water tank in which the microorganisms are grown to a high concentration in advance. The microorganism-immobilized carrier of the present invention may be added to immobilize the microorganisms, and then taken out and put into a septic tank for wastewater. The method of immobilizing the microorganisms in advance and then adding the microorganism-immobilized carrier to the wastewater is preferable because the time until normal purification can be shortened, and the anaerobic microorganisms grow particularly slowly, so that the anaerobic treatment is performed. Is particularly preferable. Further, the microorganisms may be immobilized on some of the microorganism-immobilized carriers in advance and then put into the septic tank.

Since the microbial-immobilized carrier of the present invention is composed of a chemically stable synthetic resin and an inorganic substance, it has good long-term storage stability and there are no particular restrictions on the storage method, but from the viewpoint of convenience of storage and transportation. , It is preferable to store it in a dry state.

It is a figure which shows the shape of the microorganism-immobilized carrier of this invention.

The present invention will be described in more detail below based on examples, but these are examples for assisting the understanding of the present invention, and the present invention is not limited by these examples.
(Evaluation of sludge adhesion and carrier fluidity)
100 mL of the carrier was put into 1 L of simulated wastewater (300 mg / L of nitrate nitrogen) containing anaerobic sludge in a container with a capacity of about 1.5 L, and kept constant at a water temperature of 20 ° C. and pH 7 under nitrogen atmosphere conditions for about 1 month. The stirring was continued slowly for a while, and the adhesion state of the microbial layer and the fluidity of the carrier were evaluated.

<Microbial adhesion>
⊚: The microbial layer adheres to the extent that the inside of the hollow cylinder is closed. ◯: The microbial layer adheres to the surface of the carrier so that it becomes almost uniform. Δ: More than half of the portion to which the microbial layer does not adhere is observed.

<Carrier fluidity>
◯: The carrier does not float and flows in the stirring tank. ×: The carrier floats and stays on the upper part of the stirring layer (Example 1).
Low density polyethylene (Petrosen 170, density 0.92 g / cm ³ , MFR = 1.0 g / 10 min, manufactured by Toso Co., Ltd.) 75 parts by weight, calcium carbonate MB (PEX10560AL, density 1.9 g / cm ³ , Tokyo Ink Co., Ltd.) (Made) 25 parts by weight and 0.1 part by weight of phenolic antioxidant (Adecastab AO-60, manufactured by ADEKA Co., Ltd.) are mixed and combined with a lab plast mill single screw extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in Fig. A die having ribs on the outside of the cylindrical shape as shown was used to perform hollow extrusion at 170 ° C., and then cooled in a cooling water tank to obtain a molded body having protrusions on the outside of the hollow cylindrical shape. Next, it is cut to a predetermined length with a utility knife, and has an outer diameter D = 10 mm, a length L = 8 mm, a thickness t = 0.8 mm, a rib width W = 0.5 mm, and a height H = 0.5 mm. A carrier having a hollow cylindrical shape with protrusions on the outside was obtained.

When the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 2)
The ribbed hollow cylinder formed body obtained in Example 1 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 10 mm, a length L = 6 mm, a thickness t = 0.8 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 3)
The ribbed hollow cylinder formed body obtained in Example 1 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 10 mm, a length L = 4 mm, a thickness t = 0.8 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 4)
The ribbed hollow cylinder formed body obtained in Example 1 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 10 mm, a length L = 2 mm, a thickness t = 0.8 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 5)
The same operation was performed except that the diameter of the die for hollow extrusion was increased in Example 1, and the outer diameter D = 15 mm, the length L = 12 mm, the thickness t = 1 mm, and the rib width W = 0.8 mm. , A carrier having a hollow cylindrical shape having a height of H = 0.8 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, sludge adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 6)
The ribbed hollow cylinder formed body obtained in Example 5 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 15 mm, a length L = 9 mm, a thickness t = 1 mm, and a rib width W = 0. A carrier having a hollow cylindrical shape having a height of 0.8 mm and a height of 0.8 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 7)
The ribbed hollow cylinder formed body obtained in Example 5 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 15 mm, a length L = 6 mm, a thickness t = 1 mm, and a rib width W = 0. A carrier having a hollow cylindrical shape having a height of 0.8 mm and a height of 0.8 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 8)
The ribbed hollow cylinder formed body obtained in Example 5 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 15 mm, a length L = 3 mm, a thickness t = 1 mm, and a rib width W = 0. A carrier having a hollow cylindrical shape having a height of 0.8 mm and a height of 0.8 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 9)
The same operation was performed except that the diameter of the die for hollow extrusion molding in Example 1 was increased, and the outer diameter D = 25 mm, the length L = 20 mm, the thickness t = 1.5 mm, and the rib width W = 1 mm. , A carrier having a height H = 1 mm and a hollow cylindrical shape with protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 10)
The ribbed hollow cylinder-formed body obtained in Example 9 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 25 mm, a length L = 15 mm, a thickness t = 1.5 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 1 mm and a height of H = 1 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 11)
The ribbed hollow cylinder-formed body obtained in Example 9 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 25 mm, a length L = 10 mm, a thickness t = 1.5 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 1 mm and a height of H = 1 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
(Example 12)
The ribbed hollow cylinder formed body obtained in Example 9 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 25 mm, a length L = 5 mm, a thickness t = 1.5 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 1 mm and a height of H = 1 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microbial layer adhered uniformly to the surface of the carrier. In addition, the carrier was flowing in the stirring layer.
The above results are summarized in Table 1.

（比較例１）
実施例１で得られたリブ付き中空円筒形成形体を、カッターナイフで所定の長さで切断し、外径Ｄ＝１０ｍｍ、長さＬ＝１０ｍｍ、厚さｔ＝０．８ｍｍ、リブの幅Ｗ＝０．５ｍｍ、高さＨ＝０．５ｍｍの中空円筒形の外側に突起がついた担体を得た。

(Comparative Example 1)
The ribbed hollow cylinder formed body obtained in Example 1 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 10 mm, a length L = 10 mm, a thickness t = 0.8 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm and having protrusions on the outside was obtained.

As in Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered to the extent that the inside of the hollow cylinder was closed. In addition, the carrier remained on the upper part of the stirring layer.
(Comparative Example 2)
The ribbed hollow cylinder formed body obtained in Example 1 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 10 mm, a length L = 15 mm, a thickness t = 0.8 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm and having protrusions on the outside was obtained.

As in Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered to the extent that the inside of the hollow cylinder was closed. In addition, the carrier remained on the upper part of the stirring layer.
(Comparative Example 3)
The ribbed hollow cylinder formed body obtained in Example 5 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 15 mm, a length L = 15 mm, a thickness t = 1 mm, and a rib width W = 0. A carrier having a hollow cylindrical shape having a height of H = 0.5 mm and having protrusions on the outside was obtained.

As in Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered to the extent that the inside of the hollow cylinder was closed. In addition, the carrier remained on the upper part of the stirring layer.
(Comparative Example 4)
The ribbed hollow cylinder formed body obtained in Example 5 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 15 mm, a length L = 2 mm, a thickness t = 1 mm, and a rib width W = 0. A carrier having a hollow cylindrical shape having a height of 0.8 mm and a height of 0.8 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, more than half of the portions to which the microbial layer did not adhere were observed. In addition, the carrier was flowing in the stirring layer.
(Comparative Example 5)
The ribbed hollow cylinder formed body obtained in Example 9 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 25 mm, a length L = 25 mm, a thickness t = 1.5 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 1 mm and a height of H = 1 mm and having protrusions on the outside was obtained.

As in Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered to the extent that the inside of the hollow cylinder was closed. In addition, the carrier remained on the upper part of the stirring layer.
(Comparative Example 6)
The ribbed hollow cylinder formed body obtained in Example 9 is cut to a predetermined length with a cutter knife, and has an outer diameter D = 25 mm, a length L = 2 mm, a thickness t = 1.5 mm, and a rib width W. A carrier having a hollow cylindrical shape having a height of 1 mm and a height of H = 1 mm and having protrusions on the outside was obtained.

Similar to Example 1, the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated. As a result, more than half of the portions to which the microbial layer did not adhere were observed. In addition, the carrier was flowing in the stirring layer.
(Comparative Example 7)
Hollow extrusion is performed in the same manner as in Example 1 except that a die without ribs is used instead of the die having ribs on the outside of the cylindrical shape in Example 1, and molding without protrusions on the outside of the hollow cylinder. I got a body. A hollow cylindrical carrier having an outer diameter of D = 10 mm, a length of L = 6 mm, and a thickness of t = 0.8 mm without ribs was obtained by cutting with a cutter knife to a predetermined length.

As in Example 1, when the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated, almost no microbial layer was attached to the outside of the carrier. In addition, the carrier was flowing in the stirring layer.
(Comparative Example 8)
Hollow extrusion was performed in the same manner as in Example 5 except that a die without ribs was used instead of the die having ribs on the outside of the cylindrical shape in Example 5, and molding without protrusions on the outside of the hollow cylinder. I got a body. A hollow cylindrical carrier having an outer diameter of D = 15 mm, a length of L = 9 mm, and a thickness of t = 1 mm without ribs was obtained by cutting with a cutter knife to a predetermined length.

As in Example 1, when the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated, almost no microbial layer was attached to the outside of the carrier. In addition, the carrier was flowing in the stirring layer.
(Comparative Example 9)
Hollow extrusion was performed in the same manner as in Example 9 except that a die without ribs was used instead of the die having ribs on the outside of the cylindrical shape in Example 9, and molding without protrusions on the outside of the hollow cylinder. I got a body. A hollow cylindrical carrier having an outer diameter of D = 25 mm, a length of L = 15 mm, and a thickness of t = 1.5 mm without ribs was obtained by cutting with a cutter knife to a predetermined length.

As in Example 1, when the carrier was put into the simulated wastewater and the adhesion of microorganisms was evaluated, almost no microbial layer was attached to the outside of the carrier. In addition, the carrier was flowing in the stirring layer.

The above results are summarized in Table 2.

Claims (2)

It is composed of synthetic resin and inorganic substance, and has an actual specific gravity of 1.0 to 1.10 g / cm ³ , an outer diameter (D) of 10 to 25 mm, a thickness (t) of 0.5 to 2 mm, and a length (L) of the outside. It has a tubular shape 0.2 to 0.8 times the diameter (D), and has a plurality of tubes on the outside of the cylinder in the length direction of width (W) 0.5 to 2 mm and height (H) 0.5 to 2 mm. A microbial immobilization carrier for wastewater treatment, which has ribs extending to the surface. A wastewater treatment method comprising contacting wastewater with the microbial immobilization carrier for wastewater treatment according to claim 1 in an anaerobic atmosphere.

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