JP4828370B2 - Method for producing microbial carrier for water treatment - Google Patents

Description

The present invention relates to a method for producing a microbial carrier for water treatment to be put into an aeration tank or the like.

  Conventionally, a method of decomposing dissolved organic matter by the action of microorganisms is frequently used for water treatment. In the water treatment using the microorganism, a water treatment microorganism carrier made of a resin foam is introduced into an aeration tank (aeration tank) or the like provided in a septic tank or the like, and works by microorganisms held in the water treatment microorganism carrier. Is used to decompose dissolved organic matter in the wastewater.

  However, since the resin foam used for the microbial carrier for water treatment usually exhibits water repellency, even if the carrier is put into an aeration tank or the like, the carrier surface is difficult to get wet with water and floats on the water surface. It is easy to remain. Therefore, there is a problem that the carrier put into the aeration tank or the like does not rotate in the waste water in the aeration tank or the like according to the flow of the waste water by aeration, and the contact efficiency between the microorganisms retained on the carrier and the waste water is poor.

  In particular, when the microbial carrier for water treatment is composed of a polyurethane foam, a foam stabilizer is often added to the polyurethane foam in order to achieve good foaming, and the foam is made hydrophobic by this foam stabilizer ( Water repellency). Therefore, even if the microbial carrier for water treatment made of polyurethane foam is thrown into an aeration tank or the like, it does not immediately sink into the water and rises like a mountain on the surface of the water, making it difficult to perform the throwing operation. There is a problem that it takes a long time to turn and the original wastewater treatment capacity cannot be fully exhibited.

  Therefore, in a microbial carrier for water treatment comprising a polyurethane foam, it is proposed to form a polyurethane foam by adding a surfactant or the like in advance to the foam raw material in order to impart hydrophilicity to the polyurethane foam. Has been. However, as described above, the polyurethane foam used as a microbial carrier for water treatment contains a foam stabilizer that exhibits hydrophobicity, so when adding a surfactant or the like that imparts hydrophilicity, A small amount of a surfactant or the like cannot impart hydrophilicity, and it is necessary to add a large amount of a surfactant or the like. However, when a large amount of a surfactant or the like is added to impart hydrophilicity, a problem arises in that the foam structure cannot be obtained because the cell structure forming the foam is not formed during the production of the polyurethane foam. Further, even when a polyurethane foam is obtained, when the obtained polyurethane foam is introduced into the drainage of an aeration tank as a microbial carrier, bubbles are generated due to the influence of a surfactant and the like, and the generated foam is polyurethane. The buoyancy of the bubbles held in the foam tends to inhibit the sedimentation of the microbial carrier for water treatment in water.

  In addition, the polyurethane foam without cell membrane was placed in water in which the surfactant was dispersed, and after sufficiently immersed, the water was squeezed and dried, thereby attaching the surfactant to the polyurethane foam without the cell membrane. It has been proposed to obtain a microbial carrier for water treatment. However, in this microbial carrier for water treatment, the surfactant dissolves from the microbial carrier for water treatment and stays in the aeration tub etc. while being put into the wastewater of the aeration tub etc. and used. May contaminate water quality.

JP 2004-250593 A JP 2001-96289 A

The present invention has been made in view of the above points, and is polyurethane foam which can be quickly settled in water after being put into an aeration tank or the like and swirled by aeration, and the water quality is less likely to be contaminated by eluted components. It aims at providing the manufacturing method of the microorganism carrier for water treatment which consists of bodies.

The invention according to claim 1 is characterized in that after the polyurethane foam is cut into small pieces of a predetermined size, the polyurethane foam small piece has a biodegradable hydrophilizing agent composed of any one of propylene glycol, ethylene glycol, and glycerin. The present invention relates to a method for producing a microbial carrier for water treatment, wherein

According to the microbial carrier for water treatment of the present invention, since the hydrophilic agent is attached to the polyurethane foam, when the microbial carrier for water treatment is put into an aeration tank or the like, the hydrophilic agent is used for water treatment. Since the surface of the microbial carrier is easily wetted with water, it is difficult for bubbles to form, and the bubbles are not easily retained in the microbial carrier for water treatment. It can be swirled by aeration and efficiently treated with microorganisms. Moreover, since the hydrophilizing agent adhering to the polyurethane foam has biodegradability, it is less likely to elute into the waste water from the water treatment microorganism carrier to contaminate the water quality. In the case of reversing the order of cutting and attachment, that is, when biodegradable hydrophilic agent is attached to polyurethane foam and then cut into small pieces, biodegradable hydrophilic agent is attached. While storing the polyurethane foam until cutting, the biodegradable hydrophilizing agent flows out of the polyurethane foam, adheres to the packing material for storage, or adheres to the cutting device. The amount of the biodegradable hydrophilizing agent that has adhered is reduced and the efficiency is deteriorated.

  The microbial carrier for water treatment in the present invention comprises a polyurethane foam to which a biodegradable hydrophilizing agent is attached. In addition, although the size and shape of the microorganism carrier for water treatment are set appropriately, a rectangular parallelepiped or a cubic shape having a side of about several mm to 70 mm is generally used.

As the polyurethane foam, a known soft polyurethane foam obtained by reacting a polyol and an isocyanate in the presence of a foaming agent and a catalyst can be used. The density of the polyurethane foam is preferably 20 to 70 kg / m ³ .

  In order to make the polyurethane foam difficult to hydrolyze, the polyol is preferably composed of a polyether polyol, or is mainly composed of a polyether polyol, and a polyether polyester polyol partially containing an ester group can also be used. . The polyether polyol is not particularly limited, for example, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, hydroquinone, water, resorcin, bisphenol A, hydrogenated bisphenol A, glycerin, trimethylolpropane, pentaerythritol, Monoethanolamine, diethanolamine, triethanolamine, tripropanolamine, ethylenediamine, 1,6-hexanediamine, tolylenediamine, diphenylmethanediamine, triethylenetetraamine, sorbitol, mannitol, dulcitol, etc. as starting materials, ethylene oxide, propylene Those obtained by adding alkylene oxide such as oxide can be used.

  The isocyanate in the present invention is not particularly limited, and may be any of aromatic, alicyclic, and aliphatic, bifunctional isocyanate having two isocyanate groups in one molecule, or one molecule. It may be a trifunctional or higher functional isocyanate having three or more isocyanate groups, and may be used alone or in combination.

  For example, as the bifunctional isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-phenylmethane diisocyanate, 2,4 ′ -Diphenylmethane diate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisonate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, etc. Aromatic ones such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, butane-1,4-diisocyanate DOO, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, mention may be made of aromatic, such as lysine isocyanate.

  Examples of the tri- or higher functional isocyanate include 1-methylbenzole-2,4,6-triisocyanate, 1,3,5-trimethylbenzole-2,4,6-triisocyanate, biphenyl-2,4,4 ′. -Triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2 ', 5,5' tetraisocyanate, triisocyanate Examples thereof include phenylmethane-4,4 ′, 4 ″ -triisocyanate, polymeric MDI, and the like.

  As the foaming agent, water is suitable. The amount of water added is generally about 1.5 to 5 parts by weight per 100 parts by weight of polyol.

  As the catalyst, those known for polyurethane foams can be used. For example, amine catalysts such as triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, tetramethylguanidine, stannous octoate, etc. And tin catalysts such as dibutyltin dilaurate and metal catalysts (also referred to as organometallic catalysts) such as phenylmercury propionate or lead octenoate. The general amount of the catalyst is about 0.05 to 0.7 parts by weight with respect to 100 parts by weight of the polyol.

  In addition, additives such as foam stabilizers and pigments can be appropriately blended. Any foam stabilizer may be used as long as it is used for polyurethane foams, and examples thereof include silicone foam stabilizers, fluorine-containing compound foam stabilizers, and known surfactants. As the pigment, those according to the required color are used.

  The polyurethane foam of the present invention is prepared by a known foaming method in which a polyurethane foam raw material comprising the polyol, isocyanate, foaming agent, catalyst, and appropriate additives is stirred and mixed to react with the polyol and isocyanate to foam. Manufactured.

  Examples of the biodegradable hydrophilizing agent attached to the polyurethane foam include one of propylene glycol (PG), ethylene glycol (EG), and glycerin (Gly). In the present invention, “having biodegradability” means that microorganisms are decomposed even when used attached to a carrier. Whether or not a hydrophilizing agent has biodegradability is determined by BOD. This can be determined by the / CODcr ratio. The biodegradable hydrophilizing agent has an appropriate amount of adhesion to the polyurethane foam, but is generally 1 to 15 g with respect to 100 g of the polyurethane foam.

  The microbial carrier for water treatment is manufactured by cutting a polyurethane foam into small pieces of a predetermined size, generally a rectangular parallelepiped or a cube-shaped piece having a side of about several millimeters to 70 mm, and then forming the green foam into small pieces of polyurethane foam. It is preferable to carry out by attaching a hydrolyzing agent having degradability. In the case of reversing the order of cutting and attachment, that is, when biodegradable hydrophilic agent is attached to polyurethane foam and then cut into small pieces, biodegradable hydrophilic agent is attached. While storing the polyurethane foam until cutting, the biodegradable hydrophilizing agent flows out of the polyurethane foam, adheres to the packing material for storage, or adheres to the cutting device. The amount of the biodegradable hydrophilizing agent that has adhered is reduced and the efficiency is deteriorated.

  A method of attaching a biodegradable hydrophilizing agent to the polyurethane foam pieces can be carried out by an appropriate method. For example, as shown in FIG. 1 (1 -A), a predetermined amount of polyurethane foam small pieces 51 obtained by the cutting are put into the stirring tank 11, and then as shown in FIG. 1 (1 -B). In addition, a method of spray-applying the biodegradable hydrophilizing agent 41 to the polyurethane foam small piece 51 with the spray coating device 31 while stirring the polyurethane foam small piece 51 with the stirring blade 24 can be mentioned. Reference numeral 21 denotes a rotary shaft to which the stirring blade 24 is attached, and 22 denotes a motor that rotates the rotary shaft 21.

Examples of the present invention will be specifically described below. Polyether polyol (hydroxyl value 56 mgKOH / g, product name: Sannix GP-3050, manufactured by Sanyo Chemical Industries, Ltd.) 100 parts by weight, foaming agent (water) 1.7 parts by weight, amine catalyst (product name: Kao Riser No. 31) 0.3 parts by weight, manufactured by Kao Corporation, tin catalyst (stannous octylate, product name: MRH110, manufactured by Johoku Chemical Industry Co., Ltd.), 0.2 parts by weight, foam stabilizer (silicone surfactant, product name: B8110, manufactured by Goldschmidt Co., Ltd.) 1 part by weight, polyisocyanate (2,4-TDI / 2,6-TDI = 80/20, product name: Coronate T-80, manufactured by Nippon Polyurethane Industry Co., Ltd.) 27.7 parts by weight A polyurethane foam block is produced by a known polyurethane slab foaming method using a foaming material comprising isocyanate index 110. It was. In the slab foaming method, the mixed and stirred foam material is discharged onto a belt conveyor, and while the belt conveyor moves, the foam material is naturally foamed and cured at room temperature and atmospheric pressure, and further cured in a drying furnace. And then cutting into a predetermined block shape. The resulting polyether-based polyurethane foams were Tsu Oh density 48 kg / ^{m 3.}

  The polyurethane foam block produced in this manner was cut into small pieces of a 10 mm side cube with a Thomson blade, and 6.75 kg of the obtained polyurethane foam pieces were put into the stirring tank shown in FIG. Spraying propylene glycol (PG), ethylene glycol (EG), and glycerin (Gly) as biodegradable hydrophilizing agents onto small pieces of polyurethane foam while stirring with a propeller mixer at a rotational speed of 60 times / minute Each was applied with an apparatus and stirred for 15 minutes. Then, stirring was stopped and the microbial carrier for water treatment of Examples 1-5 was obtained. Table 1 shows the application amount (adhesion amount) of the biodegradable hydrophilizing agent to the polyurethane foam pieces.

  When the microbial carriers for water treatment of Examples 1 to 5 obtained in this way were dropped on a static water surface and examined for sinking after 30 minutes, all of them submerged below the water surface, and the sinkability was good. there were. Moreover, when the microbial carrier for water treatment of the Example which submerged under the said water surface was stirred for 5 minutes with the stirring rod, it has confirmed that there was almost no foaming. Moreover, the presence or absence of stickiness was examined by touching the microbial carriers for water treatment of Examples 1 to 5 by hand. If the microbial carrier for water treatment is sticky, it is difficult to handle the microbial carrier for water treatment, and the microbial carrier for water treatment may remain in the packing bag when it is put into the aeration tank.

  Furthermore, CODcr (chemical oxygen demand) and BOD (biological oxygen demand) were measured in order to investigate the contamination of water quality due to the eluted components of the microbial carrier for water treatment of the examples. CODcr was measured by a known method using potassium dichromate. The measurement results are as shown in Table 1.

  For comparison, a microbial carrier for water treatment of Comparative Examples 1 to 7 was produced using a surfactant in place of the biodegradable hydrophilizing agent. In Comparative Examples 1 to 3, the surfactants are product names: acetylenol EH, manufactured by Kawaken Fine Chemical Co., Ltd., in Comparative Examples 4, product names: PEG-200, manufactured by Sanyo Chemical Industries, Ltd., and in Comparative Example 5, product names: PEG-400, Sanyo. In Comparative Example 6, product name: PP-200, manufactured by Sanyo Chemical Industries, Ltd., and in Comparative Example 7, product name: PP-400, manufactured by Sanyo Chemical Industries, Ltd. In addition, the application amount (adhesion amount) of the surfactant with respect to the polyurethane foam piece in the comparative example is as shown in Table 2. Further, for the comparative example, CODcr (chemical oxygen demand) and BOD (biological oxygen demand) were measured, and the presence or absence of stickiness was also examined. The results are as shown in Table 2.

  As can be understood from the results of Tables 1 and 2, the water treatment microbial carrier of the example had a BOD / CODcr ratio higher by one digit or more than the water treatment microbial carrier of the comparative example. It can be seen that the microbial carrier for treatment is a carrier that promotes the degradation of the hydrophilizing agent by microorganisms. In addition, the microbial carrier for water treatment in the examples was not sticky, whereas the microbial carrier for water treatment in the comparative examples was sticky.

It is a figure which shows an example of the method of apply | coating the hydrophilizing agent which has biodegradability to a polyurethane foam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Stirrer tank 24 Stirrer blade 31 Spray coating device 41 Hydrophilic agent having biodegradability 51 Small piece of polyurethane foam

Claims (1)

  After the polyurethane foam is cut into small pieces of a predetermined size, a biodegradable hydrophilizing agent made of any one of propylene glycol, ethylene glycol, and glycerin is attached to the small pieces of the polyurethane foam. A method for producing a microbial carrier for water treatment.

Images