WO1998004616A1 - Porous spherical polyvinyl acetal particles, process for producing the same, and microbial carriers - Google Patents

Abstract

Porous spherical particles being excellent in mechanical strength and abrasion resistance, having an affinity for microorganisms, and being appropriately usable as microbial carriers; and a process whereby these particles can be easily produced at a high productivity. The above-mentioned particles comprise a polyvinyl acetal resin as the skeleton and have a porosity of 50 to 95 % and a degree of acetalization of 30 to 85 % by mol. The above-mentioned process comprises dropping an aqueous solution containing a mixture dissolved therein of polyvinyl alcohol, a water-soluble polymer capable of gelling via an ion exchange reaction and aldehydes into an acidic solution and solidifying the droplets through the reaction between the polyvinyl alcohol and the aldehydes. The particles are appropriate as microbial carriers, in particular, those to be used in waste water treatment tanks of the fluidized bed type.

Description

 Description POBI'-Diacetal porous spherical particles, method for producing the same, and microorganism carrier

Technical field

 The present invention relates to porous spherical particles and a method for producing the same. More specifically, a porous spherical particle having a skeleton of a polyvinyl acetal resin particularly preferably used as a fluidized bed type microorganism carrier, and a porous spherical particle thereof are preferably produced. The present invention relates to a method for producing porous spherical particles. Background art

 A method of filling a reactor with microorganisms and enzymes and using the reaction of the microorganisms and enzymes to obtain a product is a so-called bioreactor, which is used in the fields of food, pharmaceuticals, chemicals, and sewage. It has been used more industrially in the fields of wastewater and waste gas treatment. In recent years, in order to make the processing capacity more efficient, various researches have been conducted on means for filling the microbial biocatalyst with high density in the reaction tank.

 The most typical one of the means is a method in which microorganisms are supported on a granular carrier, and more specifically, a biofilm method in which microorganisms are supported on a carrier surface and a biofilm is used, and a carrier. The microbial immobilization method for immobilizing microorganisms inside a cell is divided into two methods. The material of the carrier includes a polymer substance and an inorganic substance, and the form of use of the carrier is also fixed, and the carrier is immobilized inside the reaction tank, or a fixed bed type or a carrier is made to flow. A fluidized bed type is used while using.

In particular, the fluidity and specific gravity of a carrier used in a fluidized bed type are important. For this reason, it is common to use a polymer-based granular carrier rather than an inorganic carrier. Examples of the material of the carrier include gel-like granules such as polyvinyl alcohol gel (PVA gel), acrylonitrile midgel, and polyethylene glycol gel, and polyethylene, polyurethane, and polystyrene. Various methods using a porous granular material such as vinylidene dichloride and cellulose have been proposed.

 Conventionally, these granular materials have been manufactured as follows. That is, a mixture obtained by kneading additives such as a pore-forming agent, a cross-linking agent, and a catalyst into an aqueous solution in which raw materials are dissolved is poured into a large-sized reaction type, and the mixture is reacted in a hot water bath or an air bath to be insolubilized. Further, by extracting and removing the pore-forming agent by washing with water, a block-like polymer porous body can be obtained. Next, this large block-shaped polymer porous body is formed into a sheet shape by slicing to a thickness of several millimeters. By cutting into a string and cutting it into a string, and finally cutting the string-like polymer porous body by several millimeters in length, cubic particles with several millimeters of angle are produced. are doing. In addition, the large block-shaped polymer porous body is sliced to a thickness of several millimeters to form a sheet shape, and the sheet body is further reduced to several millimeters. A granular porous body can also be obtained by punching with a punching die.

By the way, properties desired for a microorganism carrier include not only affinity for microorganisms, but also flow performance, specific gravity, abrasion resistance, weather (light) resistance, and microbial resistance, and the like. These performances differ depending on the application. Among the above carrier types, the gel carrier has excellent affinity for microorganisms, but has low mechanical strength, and in particular, has a remarkably inferior abrasion resistance, and friction between carriers generated when the carrier flows. And the carrier is short due to friction with the inner wall of the reaction tank.Polyethylene, polyurethane and other porous granular materials do not have very high weather resistance, and cellulose Is itself However, there is a problem in that the carrier is susceptible to biodegradation, the carrier is easily broken down over a long period of use, and the life is short. In addition, considering the filling of the container, the improvement of the abrasion resistance, and the improvement of the fluidity as a fluidized bed type microbial carrier, the porosity of a uniform particle diameter as close as possible to a true sphere is possible. It is important to obtain granules, but this point was not always sufficient because conventional porous granules are cubic particles.

 In addition, since the conventional porous granular material is manufactured by the above-described manufacturing method, the reaction requires at least several hours, and requires three stages of forming steps after the reaction. It took at least two days to produce uniform granules in millimeter units. In the case of punching with a punching die, particles of about a few millimeters are often clogged in the punching die, and a post-treatment for removing the particles is required. Furthermore, the yield was low because the block-shaped porous body was sliced, cut or punched by post-processing.

 In this regard, as a means of greatly reducing the time required for post-processing and improving the yield, there is a method of crushing the block-like polymer without slicing it with a crusher without slicing. . Although this method can certainly shorten the processing time and increase the yield, it has been difficult to obtain porous spherical particles having a uniform particle diameter.

 In addition, in each of the above methods, since the reaction is performed for each mold, it is necessary to increase the space of the reaction tank in proportion to the increase in production volume, and the production volume is limited in limited facilities. At the same time, there was a problem that productivity was poor.

An object of the present invention is to provide a porous sphere that has high mechanical strength and abrasion resistance, and also has compatibility with microorganisms, and can be suitably used as a microorganism carrier, particularly a fluidized bed type microorganism carrier. That's where the particles come in. Again An object of the present invention is to provide a method for producing porous spherical particles that enables simple and high-production of porous spherical particles having a uniform particle shape as close as possible to a true sphere. Disclosure of the invention

 The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that porous spherical particles having a skeleton of a polyvinyl acetal resin, in particular, sponge-like porous spherical particles having a skeleton of a polyvinyl acetal resin. In particular, when porous spherical particles having a skeleton of polyvinyl formal resin are used, a material having excellent wear resistance, weather (light) resistance, microbial decomposition resistance, fluidity and microbial affinity can be obtained. I got a knowledge.

 The present invention is a porous spherical particle having a skeleton of a polyvinyl acetal resin. Further, it is a porous spherical particle made of a sponge-like polyvinyl acetal resin having communication holes as pores. Therefore, when polyvinyl acetal-based porous spherical particles, particularly polyvinyl formal (PVF) porous spherical particles are used as a carrier for microorganisms, wear resistance, weather resistance (light) resistance, and microbial degradation resistance A microorganism carrier having excellent properties, fluidity and microbial affinity can be obtained.

Such porous spherical particles are not a hydrogel structure but a sponge-like porous body having a skeleton structure of polyvinyl acetate, and therefore have excellent wear resistance and mechanical strength as compared with a gel-like body. In addition to its use as a microorganism carrier, it is also used as a solution holding material for hydroponic cultivation of agricultural crops, plant support materials, animal and plant cell culture media, artificial moss, soil improvement materials, pipe cleaning materials, filtration materials, water absorbing materials It is suitably used for such purposes. As a special use example, it can be used as an underwater flowing type cleaning member / underwater flowing type massaging member. Here, the fluid-in-water cleaning member is used to wash vegetables with delicate surfaces or vegetables with many irregularities. In order to clean the vegetable surface, put it in the water together with the vegetables, generate bubbles from the bottom of the aquarium, and publish and stir the whole to bring them into contact with the vegetables, etc. Refers to a cleaning member. The underwater-flowable massaging member is a member for obtaining a massage effect on the human body, and irritates the skin by contacting the particles with the human body while flowing the particles in a water tank such as a bathtub, thereby giving a massage. Refers to a member for obtaining an effect.

 In particular, in the case of a microorganism carrier, it has an affinity for microorganisms and has excellent fluidity, so that it can be optimally used for fluidized bed applications. In particular, porous spherical particles having a uniform particle size close to a true sphere and having a skeleton of a poly (vinyl acetal) resin are more excellent in mechanical strength and abrasion resistance, and can be used to fill a container with a microorganism carrier. Further, the present inventors have proposed a method for producing these porous spherical particles as a water-soluble polymer having a property of gelling in an acidic solution and a polyvinyl alcohol. A solution containing alcohol and aldehydes is dropped into an acidic solution, the droplets are gelled, and the polyvinyl alcohol in the droplets is reacted with the aldehydes to form polyvinyl alcohol. It has been found that porous spherical particles having a skeleton of an acetal-based resin can be obtained.

According to the present production method, the droplets of the stock solution forming the particles are brought into contact with the reaction solution and directly formed into particles, so that the acetalization treatment and the process of forming the spherical particles can be performed simultaneously. Also, since it contains a water-soluble polymer that gels when it comes into contact with an acid, which is a catalyst for acetylation, the shape of the droplet does not collapse. Therefore, it is possible to easily produce porous spherical particles having a uniform particle shape close to a true sphere, without requiring multiple steps as in the related art, with high productivity. BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a porous spherical particle having a skeleton of a polyvinyl acetal resin. Further, it is a porous spherical particle made of a sponge-like polyvinyl acetal resin having communication holes as pores.

 The polyvinyl acetal porous spherical particles obtained in the present invention are obtained by reacting polyvinyl alcohol with aldehydes. The raw material polyvinyl alcohol is not particularly limited, but a polyvinyl alcohol having an average degree of polymerization of 50,000 to 380,000 is desirable, and it must be completely genated. It is desirable that the mixture be a mixture of a partially genated product and a low-polymerized product. When the average degree of polymerization is less than 50,000, it is difficult to obtain a material having a high porosity, and when the average degree of polymerization exceeds 380, the viscosity increases when dissolved in water. Therefore, handling becomes difficult in a process such as kneading. Polyvinyl alcohol raw materials having different degrees of polymerization can be blended and used, and those having a degree of polymerization of 300 instead of those in the above-mentioned range are also used. There is no problem with mixing. In particular, a polyvinyl alcohol resin having a low degree of polymerization may be used to adjust elasticity, flexibility, texture, porosity, and improve water absorption.

 The porosity of the polyvinyl acetal-based porous spherical particles may be set according to the intended use, and the force is not limited, and is preferably in the range of 50 to 98%. When the above porosity is less than 50%, it is difficult for the individual porosity to be adjacent to each other, and there is a tendency for closed cells to be present, whereby the water permeability is significantly impaired. Is done. If the above porosity exceeds 98%, mechanical strength such as abrasion resistance is reduced, so that there may be a disadvantage that the use is restricted depending on the use.

The degree of acetalization of the polyvinyl acetal-based porous material is not particularly limited, and the acetalization degree is preferably 30 to 85 mol%. Alternatively, a polyvinyl acetate type porous material of 45 to 70 mol% is suitable. Among them, polyvinyl formal having a degree of formalization of 30 to 85 mol%, preferably 45 to 70 mol% is preferred.

 By adjusting the degree of acetalization in this way, it is possible to obtain a microorganism carrier having flexibility and abrasion resistance. If the degree of acetalization is less than 30 mol%, the degree of molecular crosslinking is low, the strength is poor, and the fastness to friction is low. Therefore, in particular, when used as a granular porous material in a fluidized bed type, the carrier tends to wear due to friction between the carriers generated during the flow of the carriers and friction with the inner wall of the reaction vessel, and the life of the carrier is shortened. descend. Also, it is not preferable in that the resistance to microbial erosion is reduced. Another problem is that it is difficult to handle in the manufacturing process. On the other hand, when the degree of acetalization exceeds 85 mol%, the porosity decreases, the apparent specific gravity increases, and the water content decreases. In particular, it was used as a granular porous material in a fluidized bed type. In this case, sedimentation is easy, but it is difficult to float, and the flow performance in the treatment tank is reduced. In addition, it is not preferable because hydrophilicity is reduced with a decrease in the amount of residual hydroxyl groups. Also, the rebound resilience when wet becomes low, which is not preferable in terms of water absorption and durability. In particular, when a dry pressed product is used to make a compressed pressed product, even if it is moistened in a treatment tank or the like, it is difficult to or does not recover its original shape, so it is susceptible to permanent distortion, and is a pressed product. I can't do that. In this respect, the polyvinyl acetal-based porous material having an acetalization degree of 30 to 85 mol%, preferably 45 to 70 mol%, particularly a formalization degree of 30 to 85 mol%. Polyvinyl formal with a content of preferably 45 to 100 mol% is good in terms of resistance to microbial erosion, is excellent in strength, and has high friction fastness.

Therefore, the life of the carrier is improved, particularly when used as a granular porous body in a fluidized bed type. In addition, when used as a fluidized bed type granular porous material, a suitable porosity that easily floats and sinks in the treatment tank and an apparent specific gravity of a water-containing state are obtained. It has excellent fluidity because of its good hydrophilicity. In addition, the rebound resilience when wet becomes high, and even if it is subjected to dry compression processing, it is hard to receive permanent distortion even if it is a compressed press product. Even if it is wet in a processing tank or the like, it restores its original shape . Therefore, the porous spherical particles of the present invention can be made into a pressed product, and can be made into compressed porous spherical particles, which can significantly improve the transportability of the granular porous material, and When this is moistened in a processing tank, it becomes familiar with the processing solution, absorbs water and restores its original shape.

In addition, it can be floated and settled and fluidized immediately in the treatment tank, and there is no need to wait until the particles become hydrated, so that the treatment time can be significantly reduced. The compressed porous spherical particles mean particles obtained by compressing (pressing) the porous spherical particles according to the present invention in some form.

 Another important factor that determines the properties of the porous spherical particles is the specific gravity of the particles. The specific gravity of the particles can be generally controlled by the porosity described above. << Depending on the application, the specific gravity of the particles may be further reduced, that is, may be further reduced. In particular, in the case of a microorganism carrier used in a fluidized bed or the like, since fluidity is an important factor, a wide range of specific gravity control is important. Therefore, if the inside of porous spherical particles having a skeleton of a polyvinyl acetal resin having excellent wear resistance and mechanical strength is made into hollow particles, the porous structure is combined with the porous structure according to the degree of the hollow. The specific gravity of the particles can be controlled over a wide range. The hollow particles of the present invention can be easily produced by the method described below.

The apparent specific gravity of the microorganism carrier of the present invention in a water-containing state is preferably adjusted to 1.0 to 1.2. If the apparent specific gravity in a water-containing state is less than 1.0, it will be difficult to treat it simply because it floats even if it is put into the treatment tank. Lack of sex. Therefore, the apparent specific gravity of the water-containing state of the polyvinyl acetal-based porous The microbial carrier of the present invention having a ratio of 1.0 to 1.2 can exhibit appropriate fluidity satisfactorily, particularly when used as a fluidized-bed granular porous material.

 It is preferable that the microorganism carrier of the present invention has a specific gravity which is closer to the specific gravity of the liquid to be treated when the liquid to be treated is filled in the pores of the porous body. When the liquid to be treated is converted to water, the apparent specific gravity in a water-containing state is 1.

The optimum value is preferably at least 0 and still infinitely close to 1.0, and the apparent specific gravity in a practically water-containing state as a porous vinyl acetal-based porous material is 1.0 to 1.0 as described above. 1.2 is preferred, preferably 1.0 1-1.1. The true specific gravity of the material itself is optimally in the range of 1.24 to 1.28, preferably in the range of 1.25 to 1.26. When a polyvinyl acetal-based porous material having a specific gravity within these ranges is used as a microorganism carrier, particularly when used as a fluidized-bed granular porous material, good fluidity is exhibited.

 It is desirable that the microorganism carrier of the present invention is a granular material having a size of 1 mm to 20 mm in a water-containing state. As a result, the flow performance can be improved and the microorganisms can be treated, and even when used in a sewage treatment device equipped with a filter for collecting particulate microbial carriers. However, the microorganism concentration can be maintained at a high level without passing through the recovery filter and flowing out of the processing liquid discharge port of the apparatus.

If the size of the particles exceeds 20 mm, it may be disadvantageous when the porous spherical particles of the present invention are used as a microorganism carrier. That is, not only the flowability of the particles is reduced, but also the effective surface area for supporting the microorganisms is reduced, so that it is difficult to maintain a high concentration of the microorganisms, and the processing ability of the microorganisms is reduced. In this regard, the smaller the particle size, the better the fluidity, and in a fluidized bed reactor, less energy is required to flow the carrier, and the processability is improved. Although the performance is improved, if the particle size is too small, specifically, if the particle size is less than 1 mm, it can be used in a sewage treatment device equipped with a filter for collecting particulate microbial carriers. There is a risk that the wastewater will pass through the collection filter and flow out of the processing wastewater discharge port of the device, making it difficult to maintain a high concentration of microorganisms. At this point, the collection filter, for example, the slit opening of the 1.5 mm ゥ edge wire screen installed at the processing solution outlet, should be made finer. You might also say that. However, since fine particles, microorganisms, and viscous products of microorganisms in the wastewater adhere to the slits and block the slits, there is a natural limit to the opening of the filter. The optimal size of the polyvinyl acetal-based porous spherical particles is also determined from the relationship with the filter for collecting the biological support.

 As described later, the size of the porous spherical particles of the present invention can be easily controlled by the size of the droplet to be dropped. Specifically, particles having an arbitrary particle size can be obtained by arbitrarily adjusting the ejection amount of the droplet and the diameter of the nozzle required for the droplet.

 The porous spherical particles according to the present invention are provided with a large number of pores having a size such that water or air of 20 to 300 // m can freely flow as an average stoma, and at the molecular level. It is different from a mere gel having a network structure of When used as a microbial carrier in a fluidized tank, organic substances, phosphorus, or nitrogen compounds in water can freely flow through pores of this size and spread. In addition, a microorganism carrier having a large number of pores having a pore diameter of 20 to 300 ^ m is easy to form a film with microorganisms, and the microorganism film formed on the surface of the carrier is separated. It is suitable because it is difficult. Further, the pore diameter can be controlled to some extent by using a manufacturing method described later.

 The sponge made of porous spherical particles according to the present invention similarly has a large number of pores large enough to allow water and air to flow freely, and

1 I) It has a moderate elasticity of about 2 to 200 × 10 3 NZ m ² at a compressive stress of 50% at a rate of 50% when swollen with water. This moderate elasticity provides good wear resistance when the carrier flows.

 In order to improve the wear resistance and mechanical strength of the porous spherical particles, it is desirable to have a film having pores on the surface of the particles and to have a porous structure inside the particles. The spherical particles produced by the production method of the present invention described later have a coating on the surface, and have excellent mechanical strength.

 The porous spherical particles of the present invention can be satisfactorily floated and flowed by aeration or the like in the treatment tank as a water-containing porous body simply by being thrown into a fluidized bed treatment tank, and furthermore, the material is further reduced in material quality. Because of the good affinity with the microorganisms, the microorganisms can adhere and perform excellent biological treatment. In addition, since the abrasion resistance is good, the abrasion hardly occurs due to the friction between the supports and the friction with the inner wall of the reaction tank when the supports flow. Furthermore, the mechanical strength is high, the weather resistance (light) and the microbial resistance are excellent, and the life of the carrier is prolonged.

 The porous spherical particles of the present invention having a poly (vinyl acetal) resin as a skeleton are excellent as a microorganism carrier.

 As described above, the microorganism carrier described above is suitable for attaching microorganisms to the surface of the carrier including the pores of the porous body, and has excellent fluidity even when granulated, and is a fluidized bed type. It is also ideal for applications. However, the comprehensive immobilized microbial method can 1) maintain microorganisms at a high concentration and achieve high-speed treatment of wastewater. 2) Immobilize specific microorganisms to process specific substances or treat organic matter. 3) Since the amount of sludge generated can be reduced, it is desirable that the method can be applied not only to the above-mentioned microbial membrane method but also to the comprehensive immobilized microorganism method. Therefore, we have developed a microorganism carrier in which microorganisms are positively immobilized in the pores of the porous body with a microorganism immobilizing agent.

As a result, wear resistance, weather (light) resistance, microbial degradation resistance, fluidity and It has excellent microbial affinity, can maintain high concentration of microorganisms, can process wastewater at high speed, and can immobilize specific microorganisms to process specific substances or collect valuable resources. And the amount of sludge generated can be reduced. In other words, it is possible to provide a microbial support that can take advantage of the advantages of the microbial membrane method and the entrapping immobilized microorganism method, and also overcome the disadvantages of both the microbial membrane method and the entrapping immobilized microorganism method.

 Here, the microorganism immobilizing agent can be variously employed and is not particularly limited, but a microorganism immobilizing agent containing sodium alginate as a main component is preferable. When sodium alginate is used as a main component, it is easily filled and fixed to polyvinyl acetal-based porous spherical particles, particularly, polyvinyl formal porous spherical particles, and has good compatibility. It is particularly good in terms of wear resistance.

 To entrap and immobilize microorganisms using a microorganism immobilizing agent, for example, porous spherical particles are impregnated with a mixed solution of a microorganism-immobilizing agent containing microorganisms, and the microorganism immobilizing agent is pored in the porous body. This can be achieved by insolubilization within.

 The microorganism carrier of the present invention may be any of a fluidized bed and a fixed bed, irrespective of the above-mentioned inclusively immobilized type (inclusively immobilized method) and the above-mentioned non-inclusively immobilized type (microbial membrane method). It is applied as a body and is applied to various bioreactor applications, including sewage treatment equipment.

 In particular, the microorganism carrier of the present invention can be suitably used as a fluidized bed type sewage treatment apparatus for treating the particulate microorganism carrier of the present invention by floating and convection in a treatment tank.

The fluidized bed type bioreactor is applicable, for example, as long as it carries out biological treatment and chemical treatment by bringing the carrier into contact with the liquid to be treated. Specifically, the present invention can be applied to an apparatus that performs not only decomposition of organic substances and the like, but also oxidation and reduction such as nitrification and denitrification and chemical reactions such as addition, substitution, conversion, and desorption. As described above, the porous spherical particles of the present invention are desirably formed into a compression press molded product. In particular, sponge granules with a water content of 10% or less, which quickly expand to a volume of 2 to 10 times when poured into water, and have a size of 1 mm or more in a water-containing state. Polyvinyl acetal-based porous spherical particles characterized by having a thickness of 20 mm are preferred.

 The compressed porous spherical particles (hereinafter abbreviated as compressed particles) obtained by compressing and pressing the porous spherical particles having a skeleton of a polyvinyl acetal resin of the present invention can be produced by a compression step and a drying step. When the compressed particles are introduced into the treatment tank as a microbial carrier, they quickly absorb water to restore the original shape and size, and at the same time, get wet and adapt to the treatment liquid, and float and sink in a short time. You will be able to On the other hand, the porous spherical particles that are not subjected to the compression press are hard to separate the air taken in, take a long time to float on the water surface, and to be able to flow. In addition, the compression press reduces the volume of the porous body, and as described above, can significantly reduce the transport cost.

 It is desirable that the compression press step be performed after the drying step. It will soon return to its original state even if it is pressed with a wet press. Polyvinyl acetal porous spherical particles manufactured under appropriate conditions can be stored for a long period of time in a compressed state by pressing under a condition where the moisture content of the particles is dried to 10% or less. When it is put into water, it quickly returns to its original shape and size.

The higher the compression ratio, the better and IZSIZIO is preferred. Compressed particles compressed to 1/2 to 1/10 swell quickly to 2 to 10 times when injected into water, and restore their original size and shape. When used as a microorganism carrier, the size of the porous spherical particles in a water-containing state is preferably 1 to 20 mm for the reasons described above. If it is desired to use the polymer immediately after being charged into the treatment tank, it is preferable to use polyvinyl acetal-based porous spherical particles in a water-containing state.

 Such porous spherical particles are used not only as a microorganism carrier as described above, but also as an enzyme-immobilized carrier, a solution holding material for hydroponic cultivation of agricultural crops, a plant supporting material, a medium for animal and plant cells, and an artificial water. It is suitably used for moss, soil improvement materials, and the like. As a special use example, it can be used as a submersible fluid type cleaning member / submersible fluid type massaging member.

 In order to use the porous spherical particles as the entrapping and immobilized microorganism carrier, the porous spherical particles are put into a liquid in which activated sludge is dispersed, and are placed on the surface of the porous spherical particles and in the Z or pores. Microorganisms can be attached and immobilized. In addition, for example, when a microorganism fixing agent is used for fixing microorganisms, the fixing agent may be dispersed in active sludge, and porous spherical particles may be introduced into the dispersion to be fixed. In this case, it is preferable to use the compressed particles because the sludge quickly penetrates into the inside of the particles.

 In particular, when sodium alginate is used as the immobilizing agent, the above-described microporous spherical particle microbial support is impregnated with a mixed solution of sodium alginate containing microorganisms, and further mixed with the sodium alginate. An aqueous solution of a polyvalent metal salt such as an aqueous solution of calcium chloride is added to the microorganism carrier obtained by impregnating the solution, and the sodium alginate is insolubilized on the surface of the porous body and in the Z or pores to cover the microorganisms. It is possible to obtain a fixed particulate porous microorganism carrier. In addition, it is preferable that the flow of the microorganism-immobilizing agent into the pores of the microorganism carrier be performed under reduced pressure.

The microbial carrier of the porous spherical particles of the present invention can be used in any of known microbial treatment apparatuses, and can be used by filling a single or multi-tank type microbial treatment tank into a microorganism treatment tank. It works effectively in both anaerobic and aerobic treatments. Further, the microorganism carrier of the present invention may be a fluidized bed. In addition, the present invention is also suitable for use as a so-called fixed-bed-type carrier in which the carrier is immobilized inside the reaction tank.

 The above-mentioned porous spherical particles can be easily produced with high productivity by the following production method.

 As one of the production methods, an aqueous solution obtained by mixing a water-soluble polymer having a property of gelling in an acidic solution, polyvinyl alcohol and aldehydes is dropped into the acidic solution, The porosity is characterized in that the droplets are gelled and, at the same time, the polyvinyl alcohol and the aldehydes in the droplets are reacted with each other to obtain porous spherical particles having a skeleton of a polyvinyl acetal resin. A method for producing spherical particles can be used.

 According to the present production method, the acetalization treatment and the molding process of the spherical particles can be performed simultaneously, so that a large number of steps are not required as in the conventional method, and the production is simple, high in production and spherical. Thus, it is possible to produce porous spherical particles having a uniform particle diameter close to the above. In addition, a film is provided on the surface of the particles, which results in excellent mechanical strength.

In this production method, a solution containing polyvinyl alcohol is reacted with an acidic solution to form droplets, and at the same time, by the action of the acidic solution as a catalyst, the reaction between the polyvinyl alcohol and aldehydes contained in the droplets is performed. It is characterized by starting acetalization at the same time. In other words, while the polyvinyl alcohol and aldehydes in the solution do not react with the acidic solution as a catalyst, they do not react and maintain the solution state, but the acetalization reaction starts simultaneously with the contact with the acidic solution. And begin to solidify. In addition, water-soluble polymers that gel in an acidic solution contained in a solution, for example, water-soluble polymers that gel in an ion exchange reaction, are immediately ion-exchanged by the action of an acid. As a result, it becomes a gel-like substance and has viscosity, preventing the spherical form from being deformed until the reaction between the polyvinyl alcohol and the aldehydes is completed. Play a role. In the production method of the present invention, it is possible to knead microorganisms into an aqueous solution composed of polyvinyl alcohol, a water-soluble polymer, and aldehydes to obtain an entrapping immobilization carrier. Necessary processing such as adjustment of the composition according to the purpose can also be taken.

 The particles obtained by this method become porous because, by drying the spherical particles, a gel such as calcium alginate, which is present in the polyvinyl acetal skeleton particles, is dried and shrunk. This results in the formation of voids. The reason that a film is formed on the particle surface is that a substance that functions as a pore-forming agent (both a water-soluble polymer gel and a pore-forming agent such as starch) cannot exist on the surface of the particle. This is probably because the same skeletal formation process as when reacting with aldehydes inside the particles rich in the forming agent cannot be taken. As a result, on the particle surface of the present invention in which the acetalization reaction is performed in the form of spherical particles, the porous spherical particles become particles having a thin film having fine pores on the surface, while the inside of the particles is high. The porous body has a spongy three-dimensional network structure with a porosity.

 The water-soluble polymer having the property of gelling in an acidic solution, for example, by an ion exchange reaction (the same applies to other production methods described below) is not particularly limited, and may be, for example, sodium alginate. , Carrageenan and sodium polyacrylate.

The concentration of the polyvinyl alcohol is not particularly limited, but generally, when the polyvinyl alcohol concentration is high, spherical particles are easily formed, and when the polyvinyl alcohol concentration is low, a hydrogel is formed. It will be easier. The difference in physical properties of these particles does not depend solely on the concentration of polyvinyl alcohol, but is also affected by other factors.The concentration of polyvinyl alcohol is different for spherical particles than for hydrous gel particles. Of resin skeleton It is an important main component in forming particles. Therefore, in the present invention, the amount is important. According to the present invention, when the concentration of polyvinyl alcohol exceeds 20% by weight, the viscosity of the solution becomes too high, and not only is it difficult to handle, but also it is difficult for the solution to be pulled during the dripping. Droplet-shaped particles are generated, and spherical particles having a uniform diameter or a nearly uniform diameter are hardly formed. If the polyvinyl alcohol concentration is less than 5% by weight, the strength of the spherical particles obtained by the acetalization reaction after dropping becomes low, which is not preferable. Therefore, it is desirable that the concentration of the polyvinyl alcohol be 5 to 20% by weight. In particular, 7 to 15% by weight is optimal. However, in the case of producing hollow particles by the production method described in claim 20 described below, it is preferable to lower the concentration of the particles to make it easier to produce clean particles, and it is preferable to set the concentration to about 1 to 7% by weight. is there. The temperature of the mixed solution is not particularly limited as long as it can maintain fluidity without denaturing each other, and there is no problem at room temperature.

 Examples of the aldehydes include aliphatic and aromatic aldehydes such as formaldehyde, benzaldehyde, acetate aldehyde, butyl aldehyde, acryl aldehyde and glyoxal. . An acetal that can be easily converted to an aldehyde by a coexisting acid may be used, but the reactivity with polyvinyl alcohol, water solubility, price, handleability, strength of the reaction product, and repulsion Considering the elasticity and ease of treatment after the reaction, formaldehyde is particularly excellent.

The concentration of the aldehydes is not particularly limited, but is important because it affects the degree of acetalization of the resin skeleton particles. In the present invention, it is necessary to appropriately select an appropriate aldehyde concentration depending on the concentration of the coexisting acid catalyst and the reaction temperature. The higher the aldehyde concentration, the shorter the time to reach the desired degree of acetalization However, if it is too high, the reaction rate will be high and it will be difficult to control the degree of acetalization. In general, the higher the acetalization degree, the higher the strength, but if it is too high, when producing a porous body, the porosity decreases and the apparent specific gravity increases, and the water content decreases. In addition, the hydrophilicity decreases as the residual hydroxyl groups decrease. Also, the rebound resilience of the particles decreases.

 On the other hand, as described above, the acetalization degree is preferably in the range of 30 to 85 mol%. In particular, when it is suitably used as a fluidized bed type microbial support that requires rubber-like elasticity and relatively high hardness, it must be set to 55 to 85 mol%. At this time, the concentration of the aldehydes varies depending on the type, and when using formaldehyde, it is preferable to set the concentration to about 3 to 10% by weight.

 The water-soluble polymer having a property of gelling in an acidic solution, for example, the water-soluble polymer having a property of gelling by an ion exchange reaction is not particularly limited as described above. For example, sodium alginate, sodium carrageenan, sodium polyacrylate, and the like can be cited as examples. Considering the high gelation rate and gel state, sodium alginate can be used. The game is the best and it is preferable to use it. The molecular weight of sodium alginate is not particularly limited, but the higher the molecular weight, the faster the gelation rate and the easier it is to produce clean particles. However, when the molecular weight is too high, the viscosity of the solution is too high, and thus it is not preferable because it tends to become droplet-shaped particles. Specifically, for example, sodium alginate having a viscosity of about 30 dPa · sec at a concentration of 20 ° C. and 4% is suitably used. However, it is not limited to this.

As described above, the water-soluble polymer contained in the polyvinyl alcohol solution and having a property of gelling by, for example, an ion exchange reaction is capable of acting as a pore-forming agent and a shape maintaining agent. As long as this concentration is There is no particular limitation. In general, when these concentrations are high, the viscosity of the solution increases, which often hinders dripping. On the other hand, when the concentration is low, the reaction speed of gel formation becomes slow, and it is difficult to obtain spherical particles. In consideration of such handling, this concentration depends on the molecular weight of sodium alginate, but is preferably 0.5 to 5% by weight, particularly preferably 1 to 5% by weight in the above range of molecular weight. is there. In particular, when the concentration of sodium alginate is less than 0.5% by weight, the dispersing force becomes stronger than the surface tension of the water-soluble polymer itself on the water surface or in water, and water cannot be trapped. It spreads over the water surface. On the other hand, if the concentration of sodium alginate exceeds 5% by weight, it is difficult to obtain spherical particles having a uniform diameter as a result of injecting the yarn into the solution while pulling the yarn from the supply port.

 In the present invention, it is preferable to use an acidic solution during the production process in order to promote the reaction between the polyvinyl alcohol and the aldehyde. Although these acids are not particularly limited, for example, any one of inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and maleic acid, and organic acids may be selected and used. Particularly strong acids are preferred. In particular, sulfuric acid is optimal for handling, but it is necessary to appropriately select the type of acid to be used according to the type of polyvalent metal salt used in combination.

The aqueous solution of the polyvalent metal salt is not particularly limited, but mainly calcium chloride, zinc chloride, aluminum sulfate and the like are preferred. The concentration varies somewhat depending on the type of metal salt selected and the temperature of the aqueous solution, but when calcium chloride is used, the optimal concentration is about 1 to 20% by weight. Further, in the invention described in claim 20, when the concentration is too high, the generated gel particles become large, and the phenomenon that the particles are fused to other adjacent particles tends to occur. Occurs. In the production method described in claim 17, a small amount of a polyvalent metal salt such as calcium chloride is added to an acidic aqueous solution to obtain a spherical shape. Spherical particles having a uniform diameter can be produced without collapsing the particles.

 The polyvinyl acetal-based spherical particles produced by the production method according to claims 17 to 20 are characterized in that the polyvinyl acetal is contained in a hydrogel of a water-soluble polymer. Instead, it is obtained in a state in which a hydrogel of a water-soluble polymer such as sodium alginate is contained in the fatty bone of polyvinyl acetate. Then, as described above, the dried resin particles become porous with a fine pore diameter due to shrinkage of a gel of a water-soluble polymer such as sodium alginate. Thereby, rubbery elastic or relatively hard porous spherical resin particles can be obtained. Also, when put into water, the gel of water-soluble polymer such as contracted sodium alginate is almost restored as a hydrous gel, and it can be used as a porous structure as a dwelling place for microorganisms. When the gel contained in the particles is excluded, porous spherical particles that open to the outside are obtained. In the case of producing particles having a larger pore diameter and porosity, the particles can be produced by adding a pore-forming agent such as starch in advance to a polyvinyl alcohol solution as described later. By increasing the porosity and porosity, the removal of residual substances after the acetal reaction becomes easy, and the washing time can be shortened. In addition, an increase in porosity contributes to a reduction in apparent specific gravity, and accordingly, fluidity in water is improved.

In another embodiment of the method for producing spherical particles of the present invention, an aqueous solution obtained by mixing and dissolving a water-soluble polymer having a property of gelling by an ion exchange reaction and polyvinyl alcohol is used. Is dropped into an aqueous solution of a polyvalent metal salt, and the droplets are gelled by an ion exchange reaction to form gel-like spherical particles containing polyvinyl alcohol. Thereafter, the gel-like particles are converted into aldehyde. Polyacetal resin having a degree of acetalization of 30 to 85 mol% by reacting the polyvinyl alcohol contained in the gel-like particles with aldehydes by adding to the acidic solution containing the gel-like particles. To obtain porous spherical particles having a skeleton of Can be.

 In this production method, a hydrogel of a water-soluble polymer is not used as a main component of the spherical particles, but is used as a shape retaining means of the spherical particles. Thus, it is possible to easily and mass-produce polyvinyl acetal-based spherical particles having physical properties such as infinitely close to a uniform diameter. That is, each of polyvinyl alcohol, which is a main component of the skeleton particles to be polyvinyl acetal, and a water-soluble polymer such as sodium alginate, which has a shape-retaining action and a pore-forming action for spherical particles in the production process. By adjusting the blending ratio and the degree of acetalization of polyvinyl alcohol to the above blending ratio, a polyvinyl acetal system having physical properties such as rubber elasticity and relatively hardness and having a uniform particle size close to a true sphere is obtained. This makes it possible to produce skeleton spherical particles easily and in large quantities. In addition, since the acetalization reaction is performed in a separate step, it is preferable in that the degree of acetalization can be easily adjusted as compared with the production method according to the above-described claim 17. The degree of acetalization can be controlled by adjusting the amount of the aldehydes in the reaction solution, the temperature of the reaction solution, and the reaction time.

On the other hand, as a method for producing hollow porous spherical particles having a skeleton of a polyvinyl acetal resin having excellent wear resistance and mechanical strength, as described in claim 20, An aqueous solution of a valent metal salt is dropped into an aqueous solution obtained by mixing and dissolving a water-soluble polymer having a property of gelling by ion exchange reaction and polyvinyl alcohol, and the droplet of the polyvalent metal salt is dissolved in water. The polymer is solidified by the reaction of the polymer to form a gel-like spherical particle in which a gel of a water-soluble polymer reacted with a polyvalent metal salt and polyvinyl alcohol are mixed at the outer periphery of the droplet, and then the gel The particles are obtained by adding the particles to an acidic aqueous solution containing aldehydes, and reacting the polyvinyl alcohol contained in the gel-like particles with the aldehydes. In the production method of the present invention, the polyhydric metal salt aqueous solution is dropped into the polyvinyl alcohol solution, so that the outer periphery of the droplet gels, and the polyvinyl alcohol solution cannot enter the inside of the droplet. As a result, the product is formed into hollow particles.

 As described above, the spherical particles obtained by the above-described various production methods become porous because the gel existing in the polyvinyl acetate-based skeleton particles shrinks due to drying of the spherical particles. to cause. However, when larger pores are required or when it is desired to eliminate the distribution of porosity between the outer and inner surfaces of the particles, at least the property of gelling by ion exchange reaction with polyvinyl alcohol By adding a pore-forming agent to an aqueous solution obtained by mixing and dissolving a water-soluble polymer having the above, a porous body having a large pore diameter can be produced. The pore-forming agent is not particularly limited, but the starch has a relatively uniform particle size, and the size of the particles is determined by the pore size required for the porous spherical particles of the present invention. Perfect to fit. Further, when the porous spherical particles are washed, they are relatively easily washed off with water, and handling after the particle molding is facilitated. The porous spherical particles produced by adding this pore-forming agent such as starch can be suitably used particularly as a fluidized bed type microorganism carrier.

 Further, the gel can be positively removed from the porous spherical particles having the skeleton of the polyvinyl acetal resin as described above. That is, the above porous spherical particles shrink the gel by drying to form a porous body, but when in a wet state, the gel tends to recover while exhibiting a porous structure. Therefore, by actively removing such a gel, it can be used as a porous body that is opened externally in a wet state.

The main component of the gel is a water-soluble high molecular gel that has the property of gelling with an acidic solution. For example, remove this water-soluble polymer gel such as alginic acid. As a method for removing particles, a method in which particles are added to a solution containing sodium ions and then ion-exchanged by stirring and washing, or a method such as ethylenediaminetetraacetic acid (EDTA) or a phosphate buffer is used. Examples of the method include a method using a chelating agent for calcium ions, and a method of centrifugation. Either method is a suitable gel removal method.

 The pore diameter, porosity, and acetalization degree of the present invention including the examples described below are based on the following measurement methods.

 (Measurement of pore size)

 The pore size was measured based on ASTM CDesignation: D4404-84). Specifically, the average pore diameter was determined by a mercury intrusion porosimetry using a porosimeter manufactured by PORUS MATERIALS, INC.

 (Measurement of porosity)

 Measure the sample at three points with a vernier caliper in the state of a jet, and use the apparent volume (V a) and the Shimadzu Dry Automatic Density Meter Acupic 1330 (trade name). And measure the true volume (V). Using this value, the porosity was calculated by the following equation.

 £ = (1-V a / V) x l 0 0

 (Measurement of degree of acetalization)

 The acetalization degree F (%) was calculated from the proton NMR measurement in an aqueous solution of deuterium chloroform and trifluoroacetic acid by the following equation.

 F = (a / c) x l 0 0

 c: Sum of peak intensities of methine protons (for example, 4.153, 4.442 ppm)

 a: Methylene proton adjacent to the ether group (for example, 4.66 7

, 5.150, 5.313, 5.326 ppm) Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to this. In the following Examples and Comparative Examples,% means% by weight.

 (Example 1)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 Sodium alginate 1.0%

 Holmaldehyde 4.0%

 87.5% water

 (Reaction liquid)

 Sulfuric acid 10.0%

 90.0% water

 Polyvinyl alcohol resin having an average degree of polymerization of 1500 and completely saponified is dissolved in hot water, cooled, and a separately adjusted aqueous solution of sodium alginate is added thereto. The aqueous solution of formaldehyde was added to the mixture, and mixed uniformly. Next, this mixture was dropped into a 10% aqueous sulfuric acid solution. The liquid temperature of the aqueous sulfuric acid solution was 60 ° C. The droplets formed in the aqueous sulfuric acid solution gelate in about 5 minutes, and after reacting in that state for about 5 minutes, the particles are separated.As a result, elastic particles having a resin skeleton of polyvinyl acetal are obtained. Was. This was thoroughly washed with water and dried to obtain polyvinyl acetal porous spherical particles having a uniform particle diameter close to a true sphere having a particle diameter of 3 to 4 mm.

 (Example 2)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 0% sodium alginate

Water 9 1.5% (Reaction liquid)

 50% sulfuric acid

 Holmaldehyde 40%

 Water 9 10%

 A completely saponified polyvinyl alcohol resin having an average degree of polymerization of 1500 was dissolved in hot water and then cooled, and a separately adjusted aqueous solution of sodium alginate was added thereto and mixed. This mixture was dropped into a mixture of a separately prepared aqueous solution of formaldehyde and an aqueous solution of sulfuric acid. The liquid temperature of this acidic formalin solution was 60 ° C. The dropped droplets gelled in about 5 minutes, and were reacted for about 30 minutes in this state, thereby producing elastic particles having a poly (vinyl acetal) resin skeleton. This was almost the same as that obtained in Example 1.

 (Comparative Example 1)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 Holmaldehyde 4.0%

 89.5% water

 (Reaction liquid)

 Sulfuric acid 10.0%

 90.0% water

Polyvinyl alcohol resin having an average degree of polymerization of 1500 and being completely genated was dissolved in hot water, cooled, and an aqueous formaldehyde solution was added thereto and mixed uniformly. Next, this mixture was dropped into a 10% aqueous sulfuric acid solution at a liquid temperature of 60 ° C. However, the dropped mixture does not remain as droplets but gradually diffuses into the acidic aqueous solution.At the same time, the reaction proceeds, and only a cloud-like solid is generated, and spherical particles are obtained. I couldn't do that. (Comparative Example 2)

 (Drip liquid)

 Polyvinyl alcohol 80%

 92.0% water

 (Reaction liquid)

 50% sulfuric acid

 Holmaldehyde 40%

 Water 9 10%

 A completely saponified polyvinyl alcohol resin having an average degree of polymerization of 1500 was dissolved in hot water and then cooled. Next, this mixture was dropped into a mixture of a separately prepared aqueous solution of formaldehyde and an aqueous solution of sulfuric acid. The liquid temperature of the acidic aqueous phormalin solution was 60 ° C. However, the same phenomenon as in Comparative Example 1 occurred, and spherical particles could not be obtained.

 (Example 3)

 (Drip liquid)

 Calcium chloride 20%

 Water 98%

 (1st reaction liquid)

 Polyvinyl alcohol 30%

 Alginate sodium 0 5%

 96.5% water

 (Second reaction solution)

 Holmaldehyde 80%

 Sulfuric acid 100%

 Water 8 20%

Heating a fully greased polyvinyl alcohol resin with an average degree of polymerization of 150.0 After dissolving in water, the mixture was cooled, and a separately adjusted aqueous sodium alginate solution was added thereto to obtain a mixed solution having a total volume of 2000 ml. The temperature of this mixed solution was room temperature. When an aqueous solution of calcium chloride was slowly added dropwise thereto, the droplets began to solidify and completely gelled after about 5 minutes, producing translucent spherical particles. Next, the gel-like particles were separated and collected, and further added to a mixed solution of formalin and sulfuric acid at a liquid temperature of 60 ° C. At the same time as the addition, the translucent gel-like particles began to become cloudy and completely whitened after about 10 minutes, and spherical particles having rubber elasticity and having a resin skeleton of polyvinyl acetate resin were obtained. This was sufficiently washed with water to obtain polyvinyl acetal hollow particles having a uniform particle diameter close to a true sphere having a particle diameter of 3 to 4 mm.

 (Comparative Example 3)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 Calcium chloride 5.0%

 87.5% water

 (1st reaction liquid)

 Sodium alginate 0.5%

 99.5% water

 (Second reaction solution)

 Holmaldehyde 8.0%

 Sulfuric acid 10.0%

 Water 82.0%

 Polyvinyl alcohol resin with an average degree of polymerization of 150 and completely saponified is dissolved in hot water, then cooled, and a separately prepared calcium chloride aqueous solution is added thereto to give a total of 2000 ml mixed solution. And When this solution is slowly dropped into an aqueous sodium alginate solution, the solution gels while settling and becomes semipermeable.

9 7 A light string gel formed. Next, the string-like gel was separated and collected, and then added to a mixed aqueous solution of formalin and sulfuric acid at a liquid temperature of 60 ° C. At the same time as the addition, the translucent gel-like particles began to become cloudy and completely whitened after about 10 minutes, and had rubber elasticity, but were not spherical particles nor hollow. (Comparative Example 4)

 (Drip liquid)

 Polyvinyl alcohol 5.0%

 Calcium chloride 2.0%

 Holmaldehyde 3.0%

 Sulfuric acid 4.0%

 86.0% water

 (1st reaction liquid)

 Sodium alginate 0.5%

 96.5% water

 (Second reaction solution)

 water

 When a mixture of polyvinyl alcohol resin and calcium chloride, formaldehyde, and sulfuric acid with an average degree of polymerization of 1500 and completely genated, is slowly dropped into an aqueous solution of sodium alginate, the solution is dissolved. Gelled while settling. These particles were separated, added to a water bath at 60 ° C., and allowed to react for 30 minutes, to obtain hydrophilic particles. However, the particles were not hollow particles and were inferior in strength to those obtained in Example 3. The dripping liquid remaining after the dripping was solidified after 15 minutes, and it was found that the dripping liquid had to be used up very quickly after adjusting the dripping liquid.

(Example 4)

(Drip liquid) Polyvinyl alcohol 7 5%

 Alginate sodium 10%

 Water 9 15%

 (1st reaction liquid)

 Calcium chloride 30%

 970% water

 (Second reaction solution)

 Holmaldehyde 30%

 40% sulfuric acid

 930% water

 A completely saponified polyvinyl alcohol resin with an average degree of polymerization of 1500 is dissolved in hot water, then cooled, and a separately adjusted aqueous sodium alginate solution is added thereto to bring the total amount to 200,000. ml of the mixed solution. As soon as this is slowly dropped into 500 ml of an aqueous solution of calcium chloride, the droplets begin to solidify and lose their fluidity, and after about 3 minutes are completely gelled to form translucent spherical particles. occured. Next, the gel particles were separated and collected, and further added to a mixed aqueous solution having a formaldehyde concentration of 4% and a sulfuric acid concentration of 5%. At the same time as the addition, the translucent gel-like particles began to become cloudy and completely whitened after about 3 minutes, and spherical particles having rubber elasticity were obtained. This was sufficiently washed with water to obtain polyvinyl acetal porous spherical particles having a uniform particle diameter close to a true sphere having a particle diameter of 3 to 4 mm. After drying these spherical particles, the internal structure was observed with a scanning electron microscope.As a result, they had many pores of 2 to 4 m, all of which were interconnected.

(Example 5)

 (Drip liquid)

Polyvinyl alcohol 7.5% Alginate sodium 0%

 Water 9 15%

 (1st reaction liquid)

 Calcium chloride 30%

 970% water

 (Second reaction solution)

 Holmaldehyde 80%

 Sulfuric acid 100%

 Water 8 20%

 After obtaining the gel-like particles by the same operation as in Example 4, the gel-like particles were separated and collected, and then added to a mixed aqueous solution of 80% formaldehyde and 10% sulfuric acid at 80 ° C. did. After reacting for 5 minutes in this state, 3 to 4 mm spherical particles having no elasticity were obtained. The spherical particles had fine crater-like irregularities. This was thoroughly washed with water, dried, and the internal structure was observed with a scanning electron microscope.As a result, it had many pores of 24 am, all of which were communication holes.

 (Example 6)

 (Drip liquid)

 Polyvinyl alcohol 7 5%

 Sodium alginate 10%

 Water 9 15%

 (1st reaction liquid)

 Calcium chloride 30%

 970% water

 (Second reaction solution)

Holmaldehyde 8.0% Sulfuric acid 10.0%

 93.0% water

 In the same manner as in Example 5, the gel-like particles were added to a mixed solution of 8% formaldehyde and 10% sulfuric acid at 20 ° C and reacted for 15 hours. Particles were obtained, and the particle surfaces were smoother than those obtained in Example 5.

 (Example 7)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 Sodium alginate 1.0%

 Coon Starch 5.0%

 86.5% water

 (1st reaction liquid)

 Canolecidium chloride 3.0%

 97.0% water

 (2nd reaction liquid)

 Holmaldehyde 10.0%

 Sulfuric acid 15.0%

 Water 75.0%

When the mixture prepared in the same manner as in Example 4 was dropped into 500 ml of an aqueous solution of calcium chloride at 70 ° C., the solution began to solidify, and after 15 minutes, completely gelled. Thus, translucent elastic particles were obtained. Next, the gel-like particles were added to an aqueous solution of formaldehyde and sulfuric acid at 60 ° C. and reacted for about 60 minutes to obtain white spherical particles. When stirred in this state, the particles flowed easily, and exhibited higher fluidity than that obtained in Example 4. The spherical particles obtained in this example The degree of tarification was about 67 mol%.

 (Example 8)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

 Sodium alginate 1.0%

 Corn starch 5.0%

 86.5% water

 (1st reaction liquid)

 Canolecum chloride 3.0%

 97.0% water

 (Second reaction solution)

 Holmaldehyde 10.0%

 Sulfuric acid 15.0%

 Water 75.0%

 When the mixed solution prepared in the same manner as in Example 4 was dropped into 500 ml of an aqueous solution of calcium chloride at 70 ° C., the solution began to solidify, and after 15 minutes, completely gelled. Translucent elastic particles were obtained. Next, the gel-like particles were added to an aqueous solution of formaldehyde and sulfuric acid at 75 ° C. and reacted for about 15 minutes to obtain white spherical particles. When stirred in this state, the particles flowed easily, and exhibited higher fluidity than that obtained in Example 4. The degree of acylation of the spherical particles obtained in this example was about 65 mol%.

 (Comparative Example 5)

 (Drip liquid)

 Polyvinyl alcohol 10.0%

0% sodium alginate 89.0% water

 (Reaction liquid)

 Calcium chloride 3.0%

 97.0% water

 A completely saponified polyvinyl alcohol resin having an average degree of polymerization of 1500 is dissolved in hot water and then cooled, and a separately adjusted aqueous sodium alginate solution is added thereto to bring the total amount to 200,000. ml of the mixed solution. As soon as this was slowly dropped into 500 ml of 3% aqueous solution of calcium chloride, the solution began to solidify and lost its fluidity, and after about 3 minutes completely gelled, the shape of the particles was changed. It was drop-shaped and not a true sphere.

 (Comparative Example 6)

 (Drip liquid)

 Polyvinyl alcohol 80%

 92.0% water

 (Reaction liquid)

 Calcium chloride 30%

 970% water

 An 8% aqueous solution obtained by dissolving polyvinyl alcohol resin with an average degree of polymerization of 1500 and completely converted to water is slowly dropped into 500 ml of a 3% aqueous solution of calcium chloride. However, the droplets spread on the surface of the aqueous solution of calcium chloride, and the solution did not solidify even when left in that state for 10 minutes, and no gel was obtained.

 (Comparative Example 7)

 (Drip liquid)

 Polyvinyl alcohol 7.5%

Sodium alginate 1.0% Cornstarch 50%

 86.5% water

 (1st reaction liquid)

 Calcium chloride 30%

 970% water

 (Second reaction solution)

 Holmaldehyde 1 0 0%

 Sulfuric acid 150%

 Water 750%

 When the mixture prepared in the same manner as in Example 4 was dropped into 500 m of an aqueous solution of calcium chloride at 70 ° C., the solution began to solidify, and after 15 minutes, it completely gelled. Thus, translucent elastic particles were obtained. Next, the gel-like particles were added to an aqueous solution of formaldehyde and sulfuric acid at 60 ° C. and reacted for about 15 minutes to obtain white spherical particles. When stirred in this state, the particles flowed easily, and exhibited higher fluidity than that obtained in Example 4. However, the degree of acetalization of the spherical particles obtained in this comparative example was about 30 mol%, and wear was confirmed in a durability test described later.

The spherical particles obtained in each of the examples were sponge-like open cells having a network structure, had good hydrophilicity, and were rich in flexibility and elasticity in a wet state. When 10 samples were selected as a sample of this porous body and the characteristics were measured, the porosity was uniformly dispersed between 80% and 95%, and the average porosity was 9%. 0%. In addition, the pore size was distributed between 30 and 100 / m, with an average of 60 μm. The pore diameter in this range was appropriate for maintaining microorganisms in the porous material, and was suitable for use as a carrier. The apparent specific gravity of the porous spherical particles obtained in each example in a water-containing state was about 0.17 to 1.019 per 10 samples. The specific gravity of the hollow particles of Example 3 was smaller than this and was about 1.008. The water content after centrifugal dehydration was 50.4%, and the 50% compressive stress was 20 × 10 3 NZn. When 20 grains were put into the water of a shaker beaker, they floated for a while, and all the grains gently sank below the surface in 3 minutes and 28 seconds.

 (Press test)

Next, the porous spherical particles obtained in each Example were dried at 60 ° C. for 1 hour. The water content was 3.0%. When this was pressed at a pressure of 4.9 xi06 NZm ² , it was compressed to 0.75-1.5 mm in diameter. When 20 of these were placed in shaken water, they quickly absorbed and swollen, and sank below the surface in 8 seconds. When the settled grains were taken out and measured in a state of being moistened with water to a water content of 50%, they were all poured into water and restored to the original size. In other words, it was confirmed that when it was put into water, it immediately swelled to 2 to 4 times its volume.

 On the other hand, when 20 grains of the dried sample before pressing were put into the water of a shaker beaker, all the grains floated on the water surface. Even after absorbing water, the air inside did not escape at the surface of the particles, so no particles settled below the water surface even after shaking for 2 hours.

 (Durability test)

 In addition, as a simulated test assuming the flow in the bio-reactor, the examples and comparative examples obtained in a container with a diameter of 150 mm and a height of 400 mm were used.

The porous spherical particles of No. 7 were filled so as to have a volume of 10% with respect to the amount of water, and were aerated and flown in water, whereby the particles were uniformly dispersed and flown. This flow

After operating continuously for one month, the particles were taken out and observed. The particles according to the examples did not show any wear or breakage due to friction, and were confirmed to be rich in wear resistance. However, the particles of Comparative Example 7, which had an insufficient degree of acetalization, showed wear.

 In addition, as an accelerated test to compare the abrasion resistance performance with a unit made of another material, a water-resistant sandpaper (100 count) was attached to the inner surface of the side wall of the test container as described above. Various carriers were individually filled so as to have a volume of 10% with respect to the amount of water, and stirred and fluidized in water. The stirring was set so that the stirring blades, which had been introduced into the water tank, were rotated at a speed of 300 rpm to mechanically flow the carrier, thereby generating friction with the inner wall. This flow was carried out continuously for one week, and the state of the carrier was observed over time. As a result, the porous spherical particles of the present invention did not show any abrasion due to friction, and showed that they were rich in abrasion resistance. And were confirmed.

 On the other hand, the surface of the 3 mm-diameter poly-resin bond, cellulose sponge, and calcium alginate spherical gel, which were selected as other materials, were all worn and worn after 24 hours. Was confirmed. After a week, wear progressed and the size of each material was reduced by less than half. As the calcium alginate gel, a gel prepared by dropping and solidifying a 1% aqueous sodium alginate solution into a 2% aqueous calcium chloride solution was used.

 (Test for microbial degradation of carrier)

The particles were filled in a polypropylene container having a large number of 2 mm mesh holes with about 10%, and the container was immersed in an activated sludge aeration tank. One year later, the container was taken out, and the polyvinyl acetal particles in the container were observed. No dimensional change due to abrasion was observed. In addition, aerobic microorganisms adhered to the particle surface at a high density, and erosion of the carrier by these microorganisms was not confirmed. (Manufacture of inclusive immobilized carrier)

 A mixture of activated sludge concentrated to about 50 g / 1 by centrifugation and 2% sodium alginate at a volume ratio of 1: 1 was separately prepared, and this was prepared by the above-mentioned procedure. The porous spherical particles obtained in the examples were impregnated. The mixture was flowed under reduced pressure to increase the impregnation amount.

 The microbial inclusion body obtained by impregnating the porous spherical particles with the mixed solution of sodium alginate and the microorganism is further added to a 5% calcium chloride aqueous solution and stirred, and the state is maintained for about 3 hours. And reacted. As a result, sodium alginate contained in the polyvinyl acetal-based porous material was insolubilized and immobilized in a state in which the microorganisms were included.

 The microbial entrapping immobilization support obtained in this manner has the alginate gel adhered in the pores and on the surface of the aforementioned porous spherical particles, and is hydrophilic similarly to the polyvinyl acetal porous body. It had good flexibility and was rich in flexibility and elasticity at the time of setting. Further, the porous spherical particles are polyvinyl formal and are rich in hydrophilicity, so that the gel is easily adapted to the porous spherical particles, and the gel is uniformly present in the particles. Furthermore, the high porosity and the three-dimensional network structure keep the gel ratio in the particles high.

As a simulation test assuming the flow in the bioreactor, a container with a diameter of 15 O mm and a height of 40 O mm was filled with the obtained microorganism-containing and immobilized carrier. When aerated and fluidized in water, the particles were uniformly dispersed and fluidized. After operating this flow continuously for one month, the particles were taken out and observed, but no wear or breakage due to friction was observed, and it was confirmed that they were rich in wear resistance. . In addition, the porous spherical particles did not undergo any erosion degradation by microorganisms, confirming that the life of the carrier can be maintained for a long time. From the results of the above Examples and Comparative Examples, in order to produce porous spherical particles by the production method of the present invention, a water-soluble polymer having a gelling property must be blended at an appropriate concentration. However, it is clear that it is necessary to reduce the shape to maintain the shape. For example, in the comparison between Example 1 and Comparative Example 1 and between Example 2 and Comparative Example 2, since the dropping liquid does not contain sodium alginate, the droplet formed by dropping cannot maintain the shape and the cloud The result was that the particles were shaped like particles.

 Further, as shown in Example 3, it was recognized that hollow particles could be obtained by, for example, dropping the first reaction solution of Example 1 and the dripping solution in the opposite direction. In this case, it was found that the lower the concentration of polyvinyl alcohol, the easier it was to obtain clean particles.

 Further, as is clear from Examples 7 and 8, the porosity and the pore diameter of the spherical particles could be controlled by adding a pore-forming agent such as starch to the dripping solution. When starch is used as the pore-forming agent, the temperature of the first reaction solution is set slightly higher to expand the starch, and the amount of sulfuric acid in the second reaction solution is increased because the starch consumes sulfuric acid. It has been found that setting to the value gives better results. It was also found that the acetalization time could be significantly reduced by slightly raising the temperature of the second reaction solution.o

In addition, all of the algae obtained in these examples are excellent in use as a carrier for immobilizing microorganisms, and have good results in flow performance, specific gravity, abrasion resistance, weather resistance (light) resistance, and microbial degradation resistance. Was something. In addition, it has been found that compressing the spherical particles of the present invention improves water permeability and facilitates use. However, when the acetalization degree was as low as 30 mol% or less, the wear resistance was reduced. Industrial applicability

 Since the porous spherical particles of the present invention are porous spherical particles having a polyvinyl acetal-based resin as a skeleton, the porous spherical particles have high mechanical strength and abrasion resistance. It can be used for various purposes such as plant support material, culture medium for animal and plant cells, artificial moss, soil improvement material, underwater fluidized cleaning member, underwater fluidized massaging member. In particular, in the case of a microorganism carrier, in particular, a fluidized bed microorganism carrier, the carrier is hard to be worn by friction between carriers and friction with the inner wall of the reaction tank when the carrier flows, and the life of the carrier is prolonged. In addition to its affinity with microorganisms, it has excellent fluidity, specific gravity, weather resistance (light) resistance, and microbial degradation resistance, making it suitable as a fluidized bed microbial carrier and microbial inclusion support. Can be used.

 In addition, in the case of porous spherical particles having a skeleton of a polyvinyl acetal resin having a uniform particle shape close to a true sphere, it is easy to fill in various containers, further improving abrasion resistance, and a fluidized bed type microorganism. Fluidity as a carrier can also be improved.

Further, in the method for producing porous spherical particles of the present invention, since the reaction is performed in one step in the form of droplets, the reaction time and the post-processing step can be significantly reduced, and the spherical particles can be produced continuously in large quantities. Therefore, the production time can be greatly reduced, and a material excellent in strength can be obtained. Further, a granular material having an arbitrary particle size and as uniform as possible can be obtained. In addition, the yield can be improved with less loss in the post-process as in the conventional method, and the space required for the reaction can be reduced. In addition, hollow polyvinyl acetal-based porous spherical particles can be obtained, and are particularly suitably used as a fluidized bed type microorganism support. I. Porous spherical particles having a skeleton of polyvinyl acetal resin.

 2. Porous spherical particles composed of a sponge whose skeleton is a polyvinyl acetal resin.

 3. The polyvinyl acetal resin is polyvinyl formal,

The compound according to claim 1 or 2, wherein the degree of formalization is from 30 to 85 mol%.

The porous spherical particles according to the above item.

 4. The porous spherical particle according to any one of claims 1 to 3, wherein the porosity of the porous spherical particle is 50 to 98%.

 5. The porous spherical particle according to any one of claims 1 to 4, wherein the particle is a hollow body.

 6. The porous spherical particle according to any one of claims 1 to 5, which has a film having pores on the particle surface, and the inside of the particle has a porous structure. 7. The porous spherical particle according to any one of claims 1 to 6, wherein the apparent specific gravity of the porous spherical particle in a water-containing state is 1.0 to 1.2. 8. The porous spherical particle according to any one of claims 1 to 7, wherein the porous spherical particle is a granular material having a size of 1 to 20 mm in a water-containing state. 9. The porous spherical particle according to any one of claims 1 to 8, wherein the particle has an average pore diameter of 20 to 300 m.

 10. Compressed porous spherical particles based on polyvinyl acetate resin c

II. Sponge-like porous spherical particles with a water content of 10% or less, which quickly expand to a volume of 2 to 10 times when injected into water, and have a size of 1 to 10 in a water-containing state. 10. The compressed porous spherical particles according to claim 10, which has a diameter of 20 mm.

 12. Any one of claims 1 to 11 as a microorganism carrier

4 ϋ A microbial carrier characterized by using porous spherical particles having a skeleton of a polyvinyl acetal resin as described in (1).

 13. The microorganism-carrying microorganism according to claim 12, wherein microorganisms are fixed on the surface and / or in the pores of the porous spherical particle according to any one of claims 1 to 11. body.

 14. The method according to claim 1, wherein the microorganism is entrapped and immobilized by a microorganism immobilizing agent on the surface and / or in the pores of the porous spherical particles according to any one of claims 1 to 11. 3. The microorganism carrier according to item 2.

 15. The microorganism carrier according to claim 14, wherein the microorganism immobilizing agent mainly comprises sodium alginate.

 16. A bioreactor using the microorganism carrier according to any one of claims 12 to 15.

 17. An aqueous solution obtained by mixing a water-soluble polymer having a property of gelling in an acidic solution, polyvinyl alcohol and aldehydes is dropped into the acidic solution, and the droplets are gelled. At the same time, a method for producing porous spherical particles, comprising reacting polyvinyl alcohol and aldehydes in the droplets to obtain porous spherical particles having a polyvinyl acetal resin as a skeleton. o

18. An aqueous solution obtained by mixing and dissolving a water-soluble polymer having a property of gelling by ion exchange reaction and polyvinyl alcohol is dropped into a polyvalent metal salt aqueous solution, and the solution is subjected to ion exchange reaction. The droplets are gelled to form gel-like spherical particles containing polyvinyl alcohol, and then the gel-like particles are added to an acidic solution containing aldehyde, and the polyvinyl alcohol contained in the gel-like particle body is added. Production of porous spherical particles characterized by obtaining alcohol-reacted aldehydes to obtain porous spherical particles having a skeleton of polyvinyl acetal resin having an acetalization degree of 30 to 85 mol%. Method. 19. The water-soluble polymer with gelling performance is found in the aqueous solution obtained by mixing and dissolving the water-soluble polymer with gelling performance and polyvinyl alcohol.

19. The porous spherical particle according to claim 18, comprising 5 to 5% by weight, and further comprising 5 to 20% by weight of polyvinyl alcohol. Production method.

 20. Drop the polyvalent metal salt aqueous solution into an aqueous solution prepared by mixing and dissolving a water-soluble polymer having the property of gelling by ion exchange reaction and polyvinyl alcohol, and drop the polyvalent metal salt. And solidified by the reaction of the water-soluble polymer with the water-soluble polymer to form a gel-like spherical particle body in which a gel of the water-soluble polymer reacted with the polyvalent metal salt and polyvinyl alcohol are mixed at the outer periphery of the droplet. The gel-like particles are added to an acidic aqueous solution containing aldehydes, and the polyvinyl alcohol contained in the gel-like particles is reacted with the aldehydes to form a polyvinyl acetal resin as a skeleton. A method for producing porous spherical particles, characterized by obtaining hollow porous spherical particles.

 21. The aqueous solution according to any one of claims 17 to 20 which is obtained by mixing and dissolving at least a water-soluble high-molecular compound having a property of gelling by ion exchange reaction and polyvinyl alcohol. The method for producing porous spherical particles according to any one of claims 17 to 20, comprising a pore-forming agent.

 22. The method for producing porous spherical particles according to claim 21, wherein the pore-forming agent is starch.

 23. The method according to claim 17, wherein the gel contained in the spherical particles according to claims 17 to 20 is removed to obtain porous spherical particles having a polyvinyl acetal resin as a skeleton. Item 30. The method for producing porous spherical particles according to Item 20.

24. The spherical particles obtained in claims 17 to 20 are pressed to extrude gas contained in the pores of the porous spherical particles, and the spherical particles are also extruded. Of compressed porous spherical particles obtained by compressing spheroids into a volume of one half to one tenth.

Claims

Claims of amendment

[1 February 29, 1997 Accepted by the International Bureau: Claims 1, 2, 2, 17, 17, 18 and 20 at the time of filing were amended; The range is unchanged. (Page 4)]

I. (After correction) Porous spherical particles made of elastic sponge with a poly (vinyl acetal) resin skeleton.

 2. The porous spherical particle according to claim 1, comprising a sponge having a communication hole as a pore (after correction).

 3. The porous spherical particles according to claim 1 or 2, wherein the polyvinyl acetal resin is polyvinyl formal and has a formalization degree of 30 to 85 mol%.

 4. The porous spherical particle according to any one of claims 1 to 3, wherein the porosity of the porous spherical particle is 50 to 98%.

 5. The porous spherical particle according to any one of claims 1 to 4, wherein the particle is a hollow body.

 6. The porous spherical particle according to any one of claims 1 to 5, having a coating having pores on the surface of the particle, wherein the inside of the particle has a porous structure.

 7. The porous spherical particle according to any one of claims 1 to 6, wherein an apparent specific gravity of the porous spherical particle in a water-containing state is 1.0 to 1.2.

 8. The porous spherical absorpti according to any one of claims 1 to 7, wherein the porous spherical particles are granular having a size of 1 to 2 Omm in a water-containing state.

9. The porous spherical particle according to any one of claims 1 to 8, wherein the porous spherical particle has an average pore diameter of 20 to 300 m.

 10 0. A compressed porous spherical abduct having a skeleton of polyvinyl acetal resin.

II. Sponge-like porous spherical particles with a water content of 10% or less, which rapidly expand to a volume of 2 to 10 times when poured into water, and have a size of 1 to 10 in a water-containing state. 10. The compressed porous spherical particles according to claim 10, which has a diameter of 20 mm.

44 Amended paper (Article 19 of the Convention)

12. (Masaura Ura) A microbial carrier characterized by using the porous spherical particles according to any one of claims 1 to 11 as a microbial carrier.

 13. The microorganism-carrying microorganism according to claim 12, wherein microorganisms are immobilized on the surface and 7 or in the pores of the porous spherical particles according to any one of claims 1 to 11. body.

 14. The method according to claim 1, wherein the microorganism is entrapped and immobilized on the surface and Z or pores of the porous spherical particles according to any one of claims 1 to 11 by a microorganism immobilizing agent. Item 3. The microorganism carrier according to Item 2.

 15. The microorganism carrier according to claim 1, wherein the microorganism immobilizing agent comprises sodium alginate as a main component.

 16. A bioreactor using the microorganism carrier according to any one of claims 12 to 15.

 17. After the correction, an aqueous solution obtained by mixing a water-soluble polymer having a property of gelling in an acidic solution, polyvinyl alcohol, and aldehydes was dropped into the acidic solution, and the droplets were dropped. A porous sponge having an elastic sponge with a polyvinyl acetal-based resin as a skeleton, characterized by reacting polyvinyl alcohol and aldehydes in the droplets at the same time as gelling. A method for producing spherical particles.

 18 (After correction) An aqueous solution obtained by mixing and dissolving a water-soluble polymer having a property of gelling by ion exchange reaction with polyvinyl alcohol is dropped into a polyvalent metal salt aqueous solution, and ion The droplets are gelled by an exchange reaction to form gel-like spherical particles containing polyvinyl alcohol, and then the gel-like particles are added to an acidic solution containing aldehyde, and contained in the gel-like particles. A polyvinyl acetal-based resin having a degree of acetylation of 30 to 85 mol%, characterized by reacting a polyvinyl alcohol with an aldehyde.

45

Amended paper (Article 19 of the Convention) A method for producing porous spherical particles made of sponge having excellent elasticity.

19. The water-soluble polymer with gelling performance is found in the aqueous solution obtained by mixing and dissolving the water-soluble polymer with gelling performance and polyvinyl alcohol.

19. The method for producing porous spherical particles according to claim 18, wherein the composition comprises 5 to 5% by weight, and the polyvinyl alcohol comprises 5 to 20% by weight. Method.

 20. (After correction) An aqueous solution of a polyvalent metal salt is dropped into an aqueous solution obtained by mixing and dissolving a water-soluble polymer having a property of gelling by ion exchange reaction and polyvinyl alcohol, and the polyvalent metal salt is added. The salt droplets are coagulated by the reaction of the water-soluble polymer with the water-soluble polymer. Forming the gel-like particles and then adding the gel-like particles to an acidic aqueous solution containing aldehydes, and reacting the polyvinyl alcohol contained in the gel-like particles with the aldehydes. A method for producing hollow, porous spherical particles comprising an elastic sponge having a vinylacetal resin as a skeleton.

 21. The aqueous solution according to any one of claims 17 to 20 wherein at least a water-soluble polymer having a property of gelling by an ion exchange reaction and polyvinyl alcohol are mixed and dissolved. The method for producing porous spherical particles according to any one of claims 17 to 20, comprising a forming agent.

 22. The method for producing porous spherical particles according to claim 21, wherein the pore-forming agent is starch.

 23. The porous spherical particles having a skeleton of a polyvinyl acetal resin by removing the gel contained in the spherical particles according to claims 17 to 20 to obtain porous spherical particles. Item 20. The method for producing porous spherical particles according to Item 20.

 24. Press the spherical particles obtained in Claims 17 to 20

46

Amended paper (Article 19 of the Convention) , Manufacturing method of the compressed porous spherical particles comprising the push the gas contained in the pores of the porous spherical particles and a monitor spherical particles compressed to 1 volume of 1 to 1 0 minutes ₂ minutes.

47 Amended paper (Article 5 of the Convention)