JP2018167228A - Microorganism-immobilized support for effluent treatment and effluent treatment method - Google Patents

Abstract

To provide a carrier which is used in anaerobic treatment, suppresses carrier levitation by gas generated by metabolic action of microorganisms, and has high effluent treatment ability having both adhesiveness and flowability of microorganisms.SOLUTION: A microorganism-immobilized support for effluent treatment is made of a synthetic resin and an inorganic substance. The microorganism-immobilized support for effluent treatment has a cylindrical shape in which a density is 1.0 to 1.10 g/cm, an outer diameter (D) is 10 to 25 mm, a thickness (t) is 0.5 to 2 mm and a length (L) is 0.2 to 0.8 times of the outer diameter (D). The microorganism-immobilized support for effluent treatment has, on the outside of the cylinder, a plurality of ribs extending in the lengthwise direction having a width (W) of 0.5 to 2 mm and a height (H) of 0.5 to 2 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microorganism-immobilized carrier for wastewater treatment used in anaerobic treatment.

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

  Anaerobic treatment methods include retention of anaerobic microorganisms, upflow anaerobic sludge bed method (UASB) and expanded sludge bed method (EGSB) using granules, and anaerobic microorganisms for membranes and carriers. There are an anaerobic fixed bed method and an anaerobic fluidized bed method using a biofilm in which sucrose is immobilized.

  In addition, the method of immobilizing microorganisms that purifies wastewater by immobilizing microorganisms that efficiently purify wastewater on the surface of inorganic and organic substances can increase the concentration of microorganisms in the wastewater, improving the efficiency of wastewater purification. However, there is an advantage that the septic tank can be downsized.

  In recent years, the fluidized bed method in which the microorganism-immobilized carrier is purified by floating and flowing in the wastewater has attracted attention in recent years because it not only has high purification efficiency but also can be stably operated for a long period of time. Specifically, as a microorganism-immobilized carrier for a 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 body (for example, Patent Document 4), and a method using a gel obtained by crosslinking PVA or PEG (for example, see Patent Documents 5 and 6).

  However, when the microorganism-immobilized carrier that is usually used in a fluidized bed is used in 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 microorganism-immobilized carrier suitable for anaerobic treatment is desired.

JP 2010-195981 A JP-A-10-257858 JP 2006-263489 A Japanese Patent Laid-Open No. 10-314780 JP 2001-089574 A JP 2004-275113 A

  The microorganism-immobilized carrier of the present invention is used in anaerobic treatment, and can suppress the carrier floating due to gas generated by the metabolic action of microorganisms, and provides a carrier with high wastewater treatment capability that has both adhesion and fluidity of microorganisms. There is.

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems. That is, it contains a synthetic resin and an inorganic substance, the density is 1.0 to 1.10 g / cm ³ , the outer diameter (D) is 10 to 25 mm, the thickness (t) is 1 to 2 mm, and the length (L) is the outer diameter ( D) is 0.2 to 0.8 times as long as the cylinder, and extends outward in the length direction of a plurality of widths (W) of 0.5 to 2 mm and heights (H) of 0.5 to 2 mm. Provided is a microorganism-immobilized carrier for wastewater treatment used in anaerobic treatment, characterized by having ribs.

  The microorganism-immobilized carrier of the present invention can be used in anaerobic treatment, can suppress carrier floating due to gas generated by the metabolic action of microorganisms, and can provide a carrier with high wastewater treatment capacity that has both adhesion and fluidity of microorganisms. . Specifically, the ratio of the outer diameter (D) to the length (L) of the carrier shape is set to 0.2 to 0.8, thereby restricting the formation of the microbial layer inside the carrier, and the inside of the carrier is the microbial layer. To prevent obstruction. As a result, the metabolic gas present in the microbial layer can be released into the waste water, and the carrier floating can be suppressed, so that fluidity in the anaerobic treatment tank can be ensured. In addition, since the ribs extending in the length direction are provided on the outer surface of the carrier, the amount of attached microorganisms can be increased and a carrier having a high wastewater treatment capacity can be provided.

The microorganism-immobilized carrier of the present invention includes 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 0.5 to 2 mm, The length (L) is 0.2 to 0.8 times the outer diameter (D), and a plurality of width (W) 0.5 to 2 mm, height (H) 0. A microorganism-immobilized carrier for wastewater treatment, comprising a rib extending in a length direction of 5 to 2 mm.

  As a material for the carrier, it is preferable to combine a synthetic resin and an inorganic substance in view of density, size, strength, flexibility, surface state, moldability, and the like. As the synthetic resin, a flexible polyolefin thermoplastic resin such as polyethylene and polypropylene is preferable, and low density polyethylene (LDPE), high density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), Examples thereof include ethylene-α-olefin copolymers such as an ethylene-propylene copolymer, an ethylene-butene copolymer, and an 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 microorganism-immobilized carrier, the preferred MFR differs depending on the carrier molding method. When molding by injection molding or the like, the MFR is 1 to 100 g / 10 min is preferable, and when forming by extrusion molding etc., MFR is 0.01-20 g / 10 min. If it is this range, a moldability will become favorable in each shaping | molding method. The MFR is measured according to JIS K 7210-1999. For example, in the case of polyethylene, the MFR 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. Examples thereof include calcium carbonate, talc, barium sulfate, iron oxide, aluminum hydroxide, zeolite, and the like, and these can be used alone or in combination of a plurality of types. Since the density of the synthetic resin is 1.0 g / cm ³ or less, these inorganic substances are combined for the purpose of adjusting the density of the synthetic resin, roughening the surface of the carrier, and imparting hydrophilicity.

  Since there is almost no difference in the carrier performance due to the material combination of the above synthetic resin and inorganic substance, the mixing ratio is adjusted so that the density and surface state fall within the target ranges. However, since it becomes easy to break when the ratio of the inorganic substance increases, the mixing ratio within the specific gravity range is also suitable from the viewpoint of strength.

  In the range not impairing the effect of the present invention, fillers, additives, processing aids, hydrophilizing agents, coloring agents, etc. may be added, but when used as a microorganism-immobilizing carrier for wastewater purification, It is desirable to make the minimum addition amount that has the least impact on the environment and organisms as much as possible.

  Examples of such additives include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, lactone antioxidants, light stabilizers, and antistatic agents. Examples of processing aids 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, and nonionic surfactants.

The microorganism-immobilized carrier of the present invention has a density of 1.0 to 1.10 g / cm ³ . When the microorganism-immobilized carrier is used for a fluidized bed, the density is preferably larger than that of water since the contact with the drainage is reduced and the purification efficiency is lowered if it floats on the water surface. On the other hand, when the density is higher than 1.10, the initial carrier sedimentation property when the carrier is introduced into the treatment tank is good, but when the microbial layer is formed by the adhesion of microorganisms, it remains submerged at the bottom of the treatment tank. , The fluidity becomes worse.

Therefore, the density of the microorganism-immobilized support is preferably 1.0 to 1.10 g / cm ³ in order to cause the support to flow and circulate with stirring with a small amount of power.

  The microorganism-immobilized carrier of the present invention has an outer diameter (D) of 10 to 25 mm. The smaller the carrier size, the larger the surface area, which is preferable from the viewpoint of adhesion of microorganisms. However, since the outflow prevention screen is reduced, problems such as clogging are likely to occur. Moreover, since fluidity | liquidity will deteriorate when too large, the outer diameter (D) of a support | carrier is 10-25 mm.

  The microorganism-immobilized carrier of the present invention has a carrier thickness (t) of 0.5 to 2 mm. If the thickness of the carrier is less than 0.5 mm, not only the strength of the carrier is lowered but also the moldability is lowered. On the other hand, when the thickness of the carrier exceeds 2 mm, not only the cost of the material is increased, but also the inner diameter of the carrier becomes small and the inside of the carrier is easily blocked by the formation of the microorganism layer, so the thickness (t) of the carrier is 0. 0.5-2 mm is preferable.

  In the microorganism-immobilized carrier of the present invention, the carrier length (L) is 0.2 to 0.8 times the outer diameter (D). By adjusting the length of the carrier within 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 present in the microorganism layer can be released into the waste water, the carrier floating can be suppressed, and the fluidity in the anaerobic treatment tank can be secured.

  In the microorganism-immobilized carrier of the present invention, the carrier has a cylindrical shape. A cup-like shape in which one end surface of the carrier is closed is not preferable because nitrogen gas generated along with the purification of drainage is accumulated inside the carrier and the carrier tends to float, and a cylindrical shape with both ends open is preferred. . In particular, a hollow cylindrical shape is preferable because it is easy to manufacture.

  The microorganism-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 increased, so that not only the amount of microorganisms loaded becomes large, but also when the carriers collide with each other in the treatment tank, the microbial layer attached to the carrier is peeled off. Can be suppressed.

  As a method for molding the microorganism-immobilized carrier of the present invention, those obtained by injection molding, extrusion molding, press molding and the like may be used as they are, and further, the carrier is cut into a predetermined size, pulverized, fused, adhered, etc. Secondary processing may be used. In particular, productivity is high, and extrusion molding with continuous molding is preferable, and hollow cylindrical extrusion molding is particularly preferable.

  Although there is no restriction | limiting in particular as an extruder used for extrusion molding, What is necessary is just to use a normal single screw extruder, a twin screw extruder, etc.

  Further, there is no restriction on the material kneading at the time of molding the carrier, but for example, it may be molded using a same-direction twin screw extruder, a single screw extruder, or the like. Further, in this case, like the kneading method described above, the material supply method is not limited by any method, but in order to improve the material supply and dispersibility, the material is preferably supplied in a master batch.

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

  In order to obtain a hollow cylindrical shape, for example, a hollow cylindrical mold such as a hose, pipe, or straw is attached to the tip of the extruder and extruded at a temperature equal to or higher than the melting point of the resin. The extruded 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 pellet cutting) to form a carrier. Alternatively, immediately after being extruded from the mold, for example, 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.

  As the temperature of extrusion molding, it is sufficient that the microorganism-immobilized carrier can be molded. However, if the molding temperature is too low, an extrusion load at the time of molding tends to be applied, and the productivity is lowered and the shape becomes unstable. 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 used for purification of waste water, microorganisms used for purification of waste water are immobilized on the surface of the carrier. Furthermore, an appropriate amount of the microorganism-immobilized carrier may be put into the wastewater and used in contact with the wastewater to be purified, depending on the properties and temperature of the wastewater, the structure of the purification tank, and the like.

  As the method for using the microorganism-immobilized carrier of the present invention, any method such as a fixed bed method and a fluidized bed method can be used. However, since the clogging inside the microorganism-immobilized carrier is small, it is preferably used in the fluidized bed method. Examples of the fluidized bed method for flowing the microorganism-immobilized carrier of the present invention in wastewater include, for example, a method of stirring with a stirring blade attached to the tip of a motor, and stirring by sucking and discharging part of the wastewater with a pump. A method of agitating the drainage by aeration of an appropriate gas, a method of agitating naturally by providing a baffle plate in the drainage tank and flowing the drainage between them, etc. There is no particular limitation in any direction. If the agitation is too weak, the microbial immobilization carrier does not flow in the wastewater and the contact between the wastewater and the microorganisms is reduced, so the purification efficiency is reduced. If the agitation is too strong, the microorganism immobilization carrier is immobilized on the surface of the microorganism immobilization carrier. Since the microorganisms peel off, it is desirable to stir at an appropriate strength (speed). Moreover, it is desirable that the purified waste water outlet has a partition having a mesh smaller than the outer diameter and length of the carrier in order to prevent the microorganism-immobilized carrier of the present invention from flowing out.

  As a method for immobilizing microorganisms on the microorganism-immobilized carrier of the present invention, the carrier may be directly injected into the waste water to naturally immobilize the microorganisms, but this method may be applied to a water tank in which microorganisms have been grown to a high concentration in advance. The microorganism-immobilized carrier of the present invention may be introduced to immobilize microorganisms and then taken out and put into a wastewater septic tank. The method of immobilizing microorganisms in advance and then introducing the microorganism-immobilized carrier into the wastewater is preferable because it can shorten the time until normal purification, and anaerobic treatment is particularly slow because anaerobic microorganisms grow particularly slowly. Is particularly preferable. Alternatively, microorganisms may be immobilized on a part of the microorganism-immobilized carrier in advance and then introduced into the septic tank.

  Since the microorganism-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 is no particular limitation on the storage method, but from the viewpoint of easy storage and transportation. It is preferable to store in a dry state.

It is a figure which shows the shape of the microorganisms fixed support | carrier of this invention.

The present invention will be described in more detail based on the following examples, but these are examples for helping understanding of the present invention, and the present invention is not limited to these examples.
(Evaluation of sludge adhesion and carrier fluidity)
100 mL of carrier is introduced into 1 L of simulated waste water (300 mg / L nitrate nitrate) 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 a pH of 7 under about 1 month. The stirring was continued slowly, and the adhesion state of the microbial layer and the fluidity of the carrier were evaluated.

<Microbe adhesion>
A: The microbial layer adheres as the inside of the hollow cylindrical shape is blocked. B: The microbial layer adheres to the carrier surface almost uniformly. Δ: More than half of the part where the microbial layer is not attached is observed.

<Carrier fluidity>
○: The carrier does not float and flows in the stirring tank ×: The carrier floats and stays in the upper part of the stirring layer (Example 1)
Low-density polyethylene (Petrocene 170, density 0.92 g / cm ³ , MFR = 1.0 g / 10 min, manufactured by Tosoh Corporation) 75 parts by weight, calcium carbonate MB (PEX10560AL, density 1.9 g / cm ³ , Tokyo Ink Co., Ltd.) 1) 25 parts by weight and 0.1 parts by weight of a phenolic antioxidant (Adeka Stub AO-60, manufactured by ADEKA Co., Ltd.) are mixed, and a lab plast mill single screw extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd.) and FIG. Using a die having a cylindrical outer rib as shown, hollow extrusion molding was performed at 170 ° C., followed by cooling in a cooling water bath to obtain a molded body having a hollow cylindrical outer protrusion. Next, it is cut with a cutter knife at a predetermined length, and the outer diameter D = 10 mm, the length L = 8 mm, the thickness t = 0.8 mm, the rib width W = 0.5 mm, and the height H = 0.5 mm. A carrier having protrusions on the outside of a hollow cylinder was obtained.

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

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

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
Example 4
The rib-formed hollow cylindrical body obtained in Example 1 was cut with a cutter knife to a predetermined length, the outer diameter D = 10 mm, the length L = 2 mm, the thickness t = 0.8 mm, the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 0.5 mm and a height H of 0.5 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
(Example 5)
The same operation was performed except that the diameter of the die at the time of hollow extrusion molding in Example 1 was increased, 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 with a protrusion on the outside of a hollow cylinder having a height H = 0.8 mm was obtained.

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

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
(Example 7)
The rib-formed hollow cylinder forming body obtained in Example 5 was cut with a cutter knife to a predetermined length, the outer diameter D = 15 mm, the length L = 6 mm, the thickness t = 1 mm, and the rib width W = 0. A carrier having a projection on the outside of a hollow cylindrical shape having a height of 0.8 mm and a height of H = 0.8 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
(Example 8)
The rib-formed hollow cylinder forming body obtained in Example 5 was cut with a cutter knife at a predetermined length, the outer diameter D = 15 mm, the length L = 3 mm, the thickness t = 1 mm, and the rib width W = 0. A carrier with a projection on the outside of a hollow cylinder having a height of 0.8 mm and a height of H = 0.8 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
Example 9
The same operation was performed except that the diameter of the die at the time of hollow extrusion molding in Example 1 was increased, 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 with a protrusion on the outside of a hollow cylinder having a height H of 1 mm was obtained.

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

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. The carrier was flowing in the stirring layer.
(Example 11)
The rib-formed hollow cylinder-shaped body obtained in Example 9 was cut with a cutter knife to a predetermined length, the outer diameter D = 25 mm, the length L = 10 mm, the thickness t = 1.5 mm, and the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 1 mm and a height H of 1 mm was obtained.

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

In the same manner as in Example 1, the carrier was put into the simulated waste water, and the adhesion of microorganisms was evaluated. As a result, the microorganism layer uniformly adhered to the surface of the carrier. 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 rib-formed hollow cylindrical body obtained in Example 1 was cut with a cutter knife to a predetermined length, the outer diameter D = 10 mm, the length L = 10 mm, the thickness t = 0.8 mm, the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 0.5 mm and a height H of 0.5 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered as the hollow cylindrical shape was blocked. Further, the carrier stayed in the upper part of the stirring layer.
(Comparative Example 2)
The rib-formed hollow cylindrical body obtained in Example 1 was cut with a cutter knife to a predetermined length, the outer diameter D = 10 mm, the length L = 15 mm, the thickness t = 0.8 mm, the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 0.5 mm and a height H of 0.5 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered as the hollow cylindrical shape was blocked. Further, the carrier stayed in the upper part of the stirring layer.
(Comparative Example 3)
The rib-formed hollow cylinder forming body obtained in Example 5 was cut with a cutter knife to a predetermined length, the outer diameter D = 15 mm, the length L = 15 mm, the thickness t = 1 mm, and the rib width W = 0. A carrier with a protrusion on the outside of a hollow cylindrical shape having a height of 0.5 mm and a height of H = 0.5 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered as the hollow cylindrical shape was blocked. Further, the carrier stayed in the upper part of the stirring layer.
(Comparative Example 4)
The rib-formed hollow cylindrical body obtained in Example 5 was cut with a cutter knife at a predetermined length, the outer diameter D = 15 mm, the length L = 2 mm, the thickness t = 1 mm, and the rib width W = 0. A carrier having a projection on the outside of a hollow cylindrical shape having a height of 0.8 mm and a height of H = 0.8 mm was obtained.

In the same manner as in Example 1, when a carrier was introduced into simulated waste water and the adhesion of microorganisms was evaluated, more than half of the parts where the microorganism layer was not adhered were observed. The carrier was flowing in the stirring layer.
(Comparative Example 5)
The rib-formed hollow cylinder-shaped body obtained in Example 9 was cut with a cutter knife to a predetermined length, the outer diameter D = 25 mm, the length L = 25 mm, the thickness t = 1.5 mm, and the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 1 mm and a height H of 1 mm was obtained.

In the same manner as in Example 1, the carrier was put into the simulated waste water and the adhesion of microorganisms was evaluated. As a result, the microorganism layer adhered as the hollow cylindrical shape was blocked. Further, the carrier stayed in the upper part of the stirring layer.
(Comparative Example 6)
The rib-formed hollow cylinder-shaped body obtained in Example 9 was cut with a cutter knife to a predetermined length, the outer diameter D = 25 mm, the length L = 2 mm, the thickness t = 1.5 mm, and the rib width W A carrier having protrusions on the outside of a hollow cylinder having a height of 1 mm and a height H of 1 mm was obtained.

In the same manner as in Example 1, when a carrier was introduced into simulated waste water and the adhesion of microorganisms was evaluated, more than half of the parts where the microorganism layer was not adhered were observed. The carrier was flowing in the stirring layer.
(Comparative Example 7)
A hollow extrusion molding is performed in the same manner as in Example 1 except that a die having no rib is used instead of the die having a rib on the outer side of the cylindrical shape in Example 1, and molding without a protrusion on the outer side of the hollow cylindrical shape. Got the body. A predetermined length was cut with a cutter knife to obtain a hollow cylindrical carrier without ribs having an outer diameter D = 10 mm, a length L = 6 mm, and a thickness t = 0.8 mm.

As in Example 1, the carrier was put into the simulated waste water and the adhesion of the microorganisms was evaluated. As a result, the microorganism layer was hardly adhered to the outside of the carrier. The carrier was flowing in the stirring layer.
(Comparative Example 8)
A hollow extrusion molding is performed in the same manner as in Example 5 except that a die without ribs is used instead of the die having ribs on the outer side of the cylindrical shape in Example 5, and molding without protrusions on the outer side of the hollow cylindrical shape. Got the body. A predetermined length was cut with a cutter knife to obtain a hollow cylindrical carrier having an outer diameter D = 15 mm, a length L = 9 mm, and a thickness t = 1 mm without ribs.

As in Example 1, the carrier was put into the simulated waste water and the adhesion of the microorganisms was evaluated. As a result, the microorganism layer was hardly adhered to the outside of the carrier. The carrier was flowing in the stirring layer.
(Comparative Example 9)
A hollow extrusion molding is performed in the same manner as in Example 9 except that a die having no rib is used instead of the die having a rib on the outer side of the cylindrical shape in Example 9. Got the body. A cutter knife was cut to a predetermined length to obtain a hollow cylindrical carrier without ribs having an outer diameter D = 25 mm, a length L = 15 mm, and a thickness t = 1.5 mm.

  As in Example 1, the carrier was put into the simulated waste water and the adhesion of the microorganisms was evaluated. As a result, the microorganism layer was hardly adhered to the outside of the carrier. The carrier was flowing in the stirring layer.

  The above results are summarized in Table 2.

Claims (2)

It consists of a synthetic resin and an inorganic substance. The actual specific gravity is 1.0 to 1.10 g / cm ³ , the outer diameter (D) is 10 to 25 mm, the thickness (t) is 0.5 to 2 mm, and the length (L) is outside. The cylinder is 0.2 to 0.8 times the diameter (D), and there are a plurality of length directions (width (W) 0.5 to 2 mm, height (H) 0.5 to 2 mm) outside the cylinder. A microorganism-immobilizing carrier for wastewater treatment, characterized by having ribs extending to the surface. A wastewater treatment method comprising contacting the wastewater treatment microorganism-immobilized support according to claim 1 and wastewater under an anaerobic atmosphere.

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