JP2009189914A - Microorganism-carrying photocatalyst-containing sintered body for water purification and its manufacturing method, and method for purifying water in water area using the sintered body and water purification process of water area using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microorganism-carrying photocatalyst-containing sintered body for water purification which is free from a concern about influence on the environment, and has an excellent microorganism-fixing property. <P>SOLUTION: A sintered body having a porous structure, obtained by burning a composition prepared by mixing dredged bottom mud obtained from the bottom of a water system, titanium oxide, and sodium silicate at a solid content weight ratio of 43-81%, 6-17%, and 13-46% respectively is made to carry microorganisms for water purification, decomposing water contaminants, and collected from a target water area to be purified, thereby obtaining the target microorganism-carrying photocatalyst-containing sintered body for water purification. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

    The present invention uses a microorganism-supported photocatalyst-containing water purification sinter for which there is no concern about the influence on the environment, a method for producing the same, and further uses such a microorganism-supported photocatalyst-containing water purification sinter. The present invention relates to a water purification method that is advantageous for water areas, particularly sea areas.

  Conventionally, in order to improve or purify polluted water quality in water areas such as rivers, ponds, swamps, and oceans, the use of microorganisms that decompose water pollutants has been considered. In order to maintain the action of water purification by microorganisms for a long time, it is considered that such microorganisms are supported on an appropriate porous carrier and administered into water intended for water purification.

    In addition, in order to improve or purify water quality contaminated with organic substances in the above water area, a method for decomposing such organic substances using the photocatalytic oxidative decomposition function of titanium oxide has been considered. In addition, in order to effectively exhibit the water purification action, titanium oxide is held on a suitable carrier and administered into water intended for water purification.

  Furthermore, in order to enhance the effect of promoting the degradation of sludge and purification of water by using the photocatalyst and the decomposition action of microorganisms together, these microorganisms and titanium oxide are supported on or held on an appropriate porous carrier to purify water. It is considered that the substance is administered in water, which is the purpose of the above, to effectively exert a water purification effect.

    For example, in Japanese Patent No. 3852844 (Patent Document 1), at least titanium oxide, zirconia, zeolite, oxidation are used as sludge decomposition / water purification agents used to decompose sludge and purify water by the action of microorganisms and photocatalysts. Porous ceramic particles made by mixing and sintering ferric oxide and manganese oxide are impregnated with halophilic bacteria, thermophilic bacteria, acidophilic bacteria, and NTAP-1 to form a sludge decomposition / water purification agent However, a method has been clarified that can be applied to harbors and lakes where sludge is accumulated and the photocatalyst and microbial decomposition action are used together to enhance the effect of promoting sludge decomposition and water purification. ing.

    In addition, in Japanese Patent No. 2613179 (Patent Document 2), porous rocks such as andesite, quartz andesite, rhyolite, shale, sandstone, lequilite, pumice tuff, mudstone, Materials containing gravel, sand, silt, clay and volcanic ash, porous rocks, scoria, scoria tuff, scoria containing materials, calcined perlite, calcined obsidian, calcined pumice, vermiculite, zeolite, mica, coral sand , Artificial shells such as sea shell, barley stone, artificial pumice, artificial gravel, artificial sand, mesalite, crisvar, porous glass, hollow glass, porous block, ceramics such as ceramics, synthetic zeolite, expandable silica, activated carbon, Inorganic porous particles such as charcoal, charcoal, coke, fly ash, blast furnace slug, foamed concrete (ALC), lightweight concrete, etc. The photocatalyst is formed by adhering the photo-semiconductor particles and microorganisms having a water purification function to the surface of the surface and the pore walls of the inorganic porous particles, and the photocatalyst is disposed at a location where the photocatalyst can come into contact with the water to be treated. Then, the photocatalyst body is irradiated with light containing ultraviolet light to purify the water to be treated by the photocatalytic function of the photocatalyst body, and is not irradiated with light containing ultraviolet light. Then, the water purification method characterized by purifying the said to-be-processed water with the microorganisms which have the water quality purification function adhering to the photocatalyst body is clarified.

    However, ceramic molded products obtained by firing zirconia, zeolite, ferric oxide, manganese oxide, etc., as well as materials such as andesite, quartz andesite, rhyolite, shale, sandstone, lechite, etc. Porous rocks, pumice tuff, mudstone, gravel, sand, silt, materials containing clay and volcanic ash, porous rocks, scoria, scoria tuff, scoria containing materials, calcined perlite, calcined obsidian, calcined pumice, bar Artificial aggregates such as mucrite, zeolite, mica, coral sand, sea shell, barley stone, artificial pumice, artificial gravel, artificial sand, mesalite, crisvar, porous glass, hollow glass, porous block, ceramics, synthetic zeolite , Ceramics such as expandable silica, activated carbon, charcoal, charcoal, coke, fly ash, blast furnace slug, foamed concrete ALC), carrier materials such as inorganic porous particles such as lightweight concrete, although they are inorganic minerals, they are artificial substances or foreign substances for the local ecosystem. When the function of microorganisms and photocatalysts is reduced, it is necessary to recover solid materials such as ceramics formations and inorganic porous particles. Otherwise, the environment of the material of the carrier material itself is required. It was also necessary to worry about the impact on the environment.

    Furthermore, depending on the particle size of the inorganic porous particles, when the microorganisms and the photocatalyst are supported and administered in water, it is difficult to move by the water flow in the water area and stay in a certain place, It was necessary to be concerned about the danger of causing problems such as increasing the turbidity of the water.

Japanese Patent No. 3852844 Japanese Patent No. 2613179

    Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that there is no concern about the influence on the environment, the microorganisms have good fixability, and the oxidation. It is to provide a microorganism-supported photocatalyst-containing water purification sinter that contains titanium, and a method for producing the same advantageously, and using such a microorganism-supported photocatalyst-containing water purification sinter, An object of the present invention is to provide a method capable of effectively purifying water in a target water area.

    And in the present invention, in order to solve such problems, dredged bottom mud obtained from the bottom of the aqueous system, titanium oxide powder having a photolytic action of organic substances and sodium silicate, solid content weight ratio In a porous structure sintered body obtained by firing a composition comprising 43 to 81%, 6 to 17%, and 13 to 46%, respectively, it is intended for water purification. The gist of the present invention is a microorganism-supported photocatalyst-containing water-purifying sintered body, which is characterized in that it carries a water-purifying microorganism that is collected from a water area and decomposes water-polluting substances.

    In addition, according to the desirable aspect of the microorganism-supported photocatalyst-containing water purification sinter according to the present invention, an anatase-type titanium oxide containing titanium oxide is used.

    Further, according to another desirable aspect of the microorganism-supported photocatalyst-containing water purification sintered body according to the present invention, the water purification microorganism is a bacterial community composed of a plurality of nitrifying bacteria and denitrifying bacteria, and a water pollutant Nitrification reaction and denitrification reaction treatment can be performed simultaneously in parallel.

    And in this invention, when purifying the water quality of the target water area using the above-mentioned microorganism-supported photocatalyst-containing water quality purification sintered body, the bottom mud that gives the sintered body is in the water area. The gist of the water quality purification method of the water area is characterized in that it is dredged mud at the bottom and the microorganism for water quality purification is a microorganism collected from the water area.

    In addition, according to a further different desirable aspect of the microorganism-supported photocatalyst-containing water purification sinter according to the present invention, the activity of microorganisms when purifying the water quality of the target water area using the water purification sinter. A carbon-containing organic substance is supplied as a chemical substance or a nutrient substance, and the water quality of the water area is effectively purified.

  Thus, in the microorganism-supported photocatalyst-containing water purification sintered body according to the present invention, the sintered body as a carrier for supporting the water purification microorganism has sufficient strength and is suitable for the target water area. Even if sprayed, it stays at the bottom without collapsing, can exhibit an effective purification action for a long time, and has excellent microbial fixability due to its porosity and material properties. Microorganisms propagate on the surface of the ligation for a long time, and the effect can be advantageously maintained. Moreover, in the water purification sintered body, the titanium oxide powder having the photocatalytic decomposition action of the organic substance is held in the porous structure sintered body mainly composed of dredged bottom mud obtained from the bottom of the aqueous system. Therefore, it will constitute a material system close to the application site, and even in sodium silicate and titanium oxide constituting such a sintered body, it will be composed of naturally abundant elements. Therefore, there is almost no possibility of secondary contamination at the site where the microorganism-supported photocatalyst-containing water purification sintered body is used. Therefore, the sintered body that has lost its purification activity by the photocatalyst and microorganisms after use ( There is no need to recover the carrier.

  Moreover, the microorganism-supported photocatalyst-containing water purification sintered body according to the present invention has sufficient strength because sodium silicate acts as a binder, and even when sprayed in a target water area, it does not collapse at the bottom. In addition to being able to exert an effective purifying action over a long period of time, the porous structure can effectively exert the water purifying action by microorganisms and titanium oxide.

  Furthermore, when the water quality purification sintered body containing the microorganism-supported photocatalyst according to the present invention as described above is used to purify the water quality of the target water area, it is taken out from the bottom of the aqueous system that gives the sintered body as the carrier. As the bottom mud, the raw material obtained in the water area, that is, the dredged bottom mud at the bottom of the water area, and the microorganisms collected from the water area are used as water purification microorganisms. The possibility of contamination can be completely eliminated, and the fixability of microorganisms can be further enhanced, so that the water purification effect can be exerted more advantageously.

    By the way, in the sintered body for purification of water containing a microorganism-supported photocatalyst according to the present invention, the dredged mud obtained from the bottom of the water system, which is the main constituent component of the sintered body having a porous structure to give it, From the bottom of water systems such as water areas and closed sea areas, which are abundant in organic matter extracted by dredging work, etc., and the bottom mud extracted from the bottom of such water systems is usually A certain amount of dehydration is performed by an operation such as drying, and the water content is about 20% to 30%. In particular, the dredged mud obtained from the bottom of the aqueous system is preferably dredged mud obtained from the bottom of the aqueous system in which the microorganism-supported photocatalyst-containing water purification sintered body formed thereby is used. In addition, it is possible to obtain a microorganism-supported photocatalyst-containing water purification sintered body that is more suitable for the on-site water area.

    Further, the component that is blended in dredged mud obtained from the bottom of such an aqueous system and imparts a photocatalytic decomposition purification function to the water purification agent according to the present invention is a titanium oxide powder having a photocatalytic decomposition action of an organic substance. When light irradiation is performed in the presence of such a titanium oxide powder, the photocatalytic decomposition ability can be effectively enhanced, and organic substances such as humic substances can be effectively decomposed and removed. . In addition, since the anatase type and the rutile type are known as the titanium oxide powder having the photocatalytic decomposition action of the organic substance, since the anatase type has higher photocatalytic activity, the anatase type is used in the present invention. Titanium oxide powder will be used advantageously. In addition, since the titanium oxide powder has a higher activity as the particle size is smaller and the specific surface area is larger, generally a fine powder of about 1 to 100 nm is preferably used. And such a titanium oxide powder will be suitably selected from various commercial items.

    Furthermore, sodium silicate blended with these dredged bottom mud and titanium oxide powder functions as a binder, and the blending imparts sufficient strength to the porous sintered body obtained by firing. Therefore, when sprayed on water systems (rivers, lakes, estuaries, sea areas, etc.) that are targeted for purification, the water purification agent does not collapse and stays at the bottom of the water system, and can exert an effective water purification effect. Is.

And these dredged bottom mud, titanium oxide, and sodium silicate are 43 to 81% and 6 to 17 in terms of solid content weight ratio in obtaining a water purification agent comprising a sintered body having a target porous structure. % And 13 to 46% in proportion. In such a blending ratio, if the blending amount of the titanium oxide powder is less than 6%, the photolysis efficiency is extremely lowered. On the other hand, if the blending amount is more than 17%, the obtained sintered body is obtained. Becomes brittle and cannot be put to practical use. Moreover, even if the blending amount of sodium silicate as a binder is less than 13%, it becomes difficult to obtain a sintered body having sufficient strength, which makes it difficult to put it into practical use. If the amount exceeds 46%, the strength of the sintered body can be increased, but the titanium oxide present on the surface of the sintered body is covered with sodium silicate, which deteriorates the surface characteristics of the body. From where the specific surface area decreases,
This may cause the possibility of adversely affecting the colonization of microorganisms, or makes it difficult to exhibit the effective photocatalytic degradation ability of titanium oxide. In particular, in the present invention, in the present invention, the composition of titanium oxide powder: 10 to 12%, sodium silicate: 30 to 40%, dredged bottom mud: the balance is advantageously employed in the solid content weight ratio. The Rukoto.

    Thus, in the present invention, there is provided a composition that comprises a dredged bottom mud as a main component and a predetermined amount of titanium oxide powder and sodium silicate blended therein to give a sintered body having a desired porous structure. In addition to these three components, such a composition may be prepared by adding various kinds of compounding agents, for example, the bottom of an aqueous system, as long as the purpose of the present invention is not impaired. It is possible to appropriately mix chemicals for agglomeration and dehydration of the bottom mud taken out from the solid, a solidifying agent, a binding aid, a pore forming aid, and the like.

    And in this invention, in order to obtain the sintered body of the porous structure which gives the target water purification | cleaning agent, the composition obtained as mentioned above is used, and it is first made into the usual granulation method. Accordingly, a granulated product having a predetermined size is formed. Next, the obtained granulated product is fired in the air to produce a desired sintered body. In the firing of such a composition, the firing temperature is generally appropriately selected at a temperature within the range of 400 to 700 ° C., and particularly preferably 600 to 700 ° C. A firing temperature within the range will be employed. If the firing temperature is too low, sufficient firing cannot be performed, which makes it difficult to sufficiently increase the strength of the sintered body, and if the firing temperature is too high, This is because the densification of the surface of the sintered body progresses and the surface properties deteriorate, making it difficult to obtain a porous structure effective for microbial fixation, or the photocatalytic decomposition action of titanium oxide is reduced. This is because it causes a problem that it is difficult to form an effective porous structure in the sintered body.

    In addition, the sintered body thus obtained has an inorganic porous material such as nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, perchloric acid or An acid aqueous solution treatment using an organic acid such as acid, acetic acid and formic acid is performed. In addition, this acid aqueous solution process is generally implemented in the time for 3 hours or more, and the upper limit will be set to about 24 hours. This is because it is difficult to expect a large change in the processing effect even if the processing time exceeds 24 hours.

In addition, by such a firing operation, the sintered body is formed as having a sufficient strength in the porous structure. Generally, such a sintered body has a thickness of 0.1 to 10 m ^2. It is desirable to have a specific surface area of about / g. However, if the specific surface area of such a sintered body becomes too small, the density of the sintered body increases, and there is a possibility that it becomes difficult to effectively fix microorganisms, and when the specific surface area becomes too large. This is because the porous structure is emphasized, the sintered body becomes brittle, and the strength may decrease. In addition, the size of such a sintered body is generally about 0.5 mm to 10 cm, preferably about 0.5 cm to 5 cm, in consideration of its handleability and the like. Will be formed.

Further, the sintered body obtained by such firing operation / required treatment is preferably uniaxial compressive strength (based on JIS R 5210 cement physical test method) as having sufficient strength in the porous structure. As a result, it is assumed that the thickness is 4.0 N / mm ² or more.

    Next, the sintered body obtained as described above is used as a carrier, and a predetermined water purification microorganism is supported on the carrier. Generally, there is a water purification microorganism as a loading method. A method of allowing microorganisms to enter and carry in the porous structure of the sintered body by immersing the sintered body in the liquid is, of course, limited to this. In addition, various known loading methods can be appropriately employed.

  In particular, according to the present invention, the culture solution obtained by culturing the water purification microorganism is concentrated, and the concentrate obtained by increasing the concentration of the microorganism is used together with the baking obtained as described above. It is advantageous to add a ligature to a medium for such microorganisms and further culture, so that the microorganisms for water purification are supported on the surface of the sintered body. Will be adopted. By doing so, microorganisms can be advantageously invaded into the porous structure of the sintered body, and effective fixing thereof can be achieved.

  Here, as the microorganisms supported on the sintered body, known various water purification microorganisms are appropriately selected and used, and among them, various ammonia oxidizing bacteria, nitrite oxidation, among others. A plurality of bacterial communities of nitrifying bacteria such as bacteria and various denitrifying bacteria are used to purify the water quality of the target water area. Among them, microorganisms that decompose water pollutants collected from water areas intended for water purification are advantageously used.

    Then, the microorganism-supported photocatalyst-containing water purification sintered body obtained as described above is charged or dispersed as a water purification agent in the target water area (sea area, etc.) and supported at the bottom. The water pollutants are effectively decomposed by the microorganisms and the water quality is purified. At that time, the sintered body has sufficient strength, so that its shape is not destroyed. Therefore, it can be effectively present in the water area. Furthermore, the photocatalytic decomposition action of the supported titanium oxide is enhanced by the light transmitted through the water, effectively decomposing and removing organic pollutants present in such water areas in parallel with or simultaneously with the decomposition by microorganisms. It can be damned. In this way, such a titanium oxide-containing (supported) fired body can exhibit an effective water purification action when applied to a predetermined water system and relatively shallow where light can reach. Thus, it was possible to effectively contribute to environmental improvement and environmental conservation in such water systems. In addition to the application to such relatively shallow water areas, the environment improvement at the bottom of relatively deep water areas is also combined with a daylighting system such as an optical fiber, and the light guided thereby contains titanium oxide according to the present invention. This can be achieved by irradiating a water purification agent comprising a sintered body.

    In addition, since the microorganism-supported photocatalyst-containing water purification sintered body that provides the water purification agent according to the present invention has sufficient strength, the shape of the sintered body collapses when applied to the water area as described above. Therefore, it can be effectively present in the applied water area. As a result, the water purification action by the microorganisms and the water purification action based on the photodecomposition action (photocatalytic resolution) of titanium oxide can be advantageously exerted over a long period of time.

    Moreover, in such a microorganism-supported photocatalyst-containing water purification sinter, the water system, particularly preferably the bottom mud taken out from the bottom of the sea area, and the water area (sea area) as a microbe for water purification is provided. By using the microorganisms collected from the water, the fixability of the microorganisms can be further enhanced, and the water purification effect in the water area (sea area) can be further advantageously exhibited. Moreover, in the water purification agent comprising the microorganism-supported photocatalyst-containing water purification sinter, the dredged bottom mud, which is the main component of the sinter, is extracted from the bottom of the aqueous system. In addition, it is of the same environment as the bottom of the water system in which such a water purification agent is used, and in addition, even in titanium oxide and sodium silicate, it consists of elements that are relatively abundant in nature. From this point, it becomes a sintered body for water purification composed of a composition close to nature, and since microorganisms are present in the water area (sea area) used, there are concerns about environmental pollution in the water area where it is applied. Therefore, there is no need to recover the water purifier according to the present invention after use.

  In the following, typical examples of the present invention will be shown, and the present invention will be clarified more specifically. However, the present invention is subject to any restrictions by the description of such examples. It goes without saying that it is not. In addition to the following examples, the present invention includes various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the specific description described above. It should be understood that improvements can be made.

  First, a sintered body as a microorganism carrier was produced as follows. That is, as the dredged mud, the marine mud containing abundant organic matter obtained from dredged water from Ago Bay in Mie Prefecture is dried naturally, and the moisture content (wet base) is about 25%. Prepared the bottom mud. Then, this marine bottom mud with adjusted moisture content, commercially available anatase-type titanium oxide fine powder (particle size: about 30 nm), and sodium silicate are blended in various proportions shown in Table 1 below, and further appropriately Water was added to obtain a uniform composition suitable for granulation. Thereafter, the composition was granulated according to a conventional method, and the obtained granulated product was further heated at a rate of temperature increase of 4 ° C./min to the target temperature shown in Table 1 below. Solidified and fired for a period of time to obtain a titanium oxide-containing sintered body (substantially spherical particles) having a diameter of about 1 cm.

    Subsequently, the titanium oxide-containing sintered granular material thus obtained is immersed in a 1M nitric acid aqueous solution for 24 hours to treat the surface of the sintered body, thereby increasing the porosity and water quality by microorganisms. The sintered body was improved in purification ability and water purification ability based on the photodecomposition action (photocatalytic resolution) of titanium oxide.

The Ago Bay bottom mud sample was collected in June 2003 from the inner bay bottom mud of Ago Bay Tategami, which is rich in organic matter at a depth of about 10 m. This basin has been used for pearl culture for many years. The analysis results of bottom mud investigated in 2001 showed that chemical oxygen demand (COD) 55.8 mgO ₂ / g · dry bottom mud, acid volatile sulfur (AVS) 1.57 mg / g · dry bottom mud, total nitrogen ( (TN) 3.77 mg / g · dry bottom mud, total organic carbon (TOC) 21.77 mg / g · dry bottom mud, water content 72.4%, redox potential (ORP) −109.3 mV. Separation of ammonia-oxidizing and denitrifying bacterial communities used as water purification microorganisms: 1) acquisition and strengthening of nitrifying bacteria, 2) activation of denitrifying bacteria, 3) depletion of heterotrophic bacteria and recovery of nitrifying bacteria It consisted of three steps.
1) Acquisition and strengthening of nitrifying bacteria Inoculate the bottom mud sample into a 500 mL medium bottle containing 400 mL of medium (3% wt / vol) and shake with a silico stopper at 20 ° C in the dark. Culture (95 rpm) was performed. Ammonia nitrogen, nitrite nitrogen, nitrate nitrogen concentration is checked once every two weeks, nitrite nitrogen concentration is 40-80 mg / L or more, ammonia nitrogen decrease, nitrate nitrogen production, About the sample by which the fall of pH was recognized, a new culture medium is inoculated 5% (vol / vol), a density | concentration is confirmed similarly, and culture | cultivation is repeated 7 to 8 times.
2) Activity of denitrifying bacteria 1-5% (vol / vol) of the sample obtained in 1) was inoculated on the medium, and static culture was performed at room temperature in the dark. In this step, 99.5% ethanol as a carbon source is added with a pH indicator to activate denitrification. The pH indicator (phenol red solution) is prepared by dissolving 25 mg of phenol red in 10 mL of ethanol and 50 mL of distilled water. After the start of culture, if denitrification activity becomes active and bubble formation and change in the color of the culture solution (from pink to yellow) are observed, culture once for about 2 weeks.
3) Depletion of heterotrophic bacteria and recovery of nitrifying bacteria Inoculate the medium with 10% (vol / vol) of the culture solution obtained in 2), and perform static culture at room temperature in the dark under the same conditions as 2) It was. The purpose of this step was to deplete the heterotrophic bacteria that had been activated in step 2) and to recover the nitrifying bacteria by culturing again with a medium composed of an inorganic salt. Cultivation was carried out for about 2 weeks until formation of nitrous acid, a decrease in ammonia nitrogen, and a decrease in pH were observed. This step was repeated once or twice, and the obtained culture broth was stored at −80 ° C. based on a conventional method.
As a result of microbial community structure analysis (PCR-DGGE), ammonia-oxidizing bacteria showed high homology with Nitrosomonas sp. Nm148 and Nitrosomonas sp. Nm107. It was suggested that it would be. Nitrosomonas spp is known to be the dominant species in the aquatic environment, and is also found in wastewater treatment plants, particularly in wastewater where high ammonia concentrations are detected. Nitrosomonas spp. And N. communis clusters are frequently detected in environments with high substrate concentrations.
In addition, bacterial communities including denitrifying bacteria were roughly classified into three groups (γ-proteobacteria, Actinobacteria, Flavobacteria). About half of them belonged to γ-proteobacteria, and the rest belonged to Actinobacteria and Flavobacteria. Half of the clones belonging to γ-proteobacteria were recognized as related species in Alcanivorax spp. And existed at any stage of the culture. Alcanivorax sp., Identified as the dominant clone, is known to undergo nitrate reduction, suggesting that these bacteria are involved in the nitrate reduction reaction. More recently, the results of genome sequencing of Alcanivorax borkumensis SK2 strain, a hydrocaubonoclastic bacterium in the ocean, have been reported. According to the results, (1) n-alkane degradation, surfactant production, biofilm production, (2) Nutrient scavengers in the oligotrophic marine environment and (3) ability to adapt to stress factors in the habitat are reported. Furthermore, this strain expresses the nnrS gene containing nirK and nor, suggesting that these bacterial species further denitrify. These closely related clones also existed, suggesting that these strains are involved in nitrate reduction and further denitrification. Some clones showed 96% homology with Pseudomonas stutzeri, which belongs to γ-proteobacteria and is well known as a denitrifying bacterium. For these, the results of analysis by the gene nirS involved in denitrification activity indicate that bacteria belonging to the genus Pseudomonas may be involved in the denitrification activity, and bacteria belonging to the genus Pseudomonas are involved in the denitrification activity. It is to support that. Dietzia maris, which showed high homology from the second dominant clone, was originally grouped as part of Rhodococcus, but was later reorganized based on biochemical data. Rhodococcus sp. Is well known as a denitrifying bacterium, but it is unclear whether the clones observed here have denitrifying activity. A third Flavobacterium group was found to have 100% homology with Vitellibacter vladivostokensis. Vitellibacter vladivostokensis is a new species belonging to Flavobacteriaceae, discovered in 2003 from the marine environment. Overall, many clones were found to have a high degree of homology with relatively recently isolated strains. In addition, as a result of analysis using a denitrification activity gene, most of the clones were derived from new strains not registered in the database or closely related to uncultured bacteria.

Using this selected ammonia-oxidizing / denitrifying bacterial community, pre-culture was first performed to confirm the survival and proliferation of the bacterial community. Specifically, 5 mL of ammonium sulfate, 2.5 mmol of sodium nitrate, 0.5 mL of phosphate buffer solution (0.5 mM), 3.5 mL of carbonate buffer solution (2.5 mM), 0.4 mL of 95% ethanol, and a small amount of inorganic components in 1 L of sterile seawater A medium (pH 7.5-8.0) was prepared by dissolving and adding a few drops of phenol red indicator. In this medium, ammonia-oxidizing / denitrifying bacterial communities were precultured at 25 ° C. for 2 weeks. As the bacterial community increases, bubbles appear and the color changes from pink to yellow. The number of viable bacteria obtained was 10 ⁶ cells / mL of ammonia oxidizing bacteria and 10 ⁸ cells / mL of denitrifying bacteria.

    The obtained ammonia oxidizing / denitrifying bacterial community concentrated solution is diluted 10 times with a medium having the same composition. By adding 10 g of the previously produced sintered body to 100 mL of this bacterial suspension solution and further culturing at a temperature of 25 ° C. for 2 weeks, the surface of the sintered body is subjected to ammonia oxidation / denitrification. Bacterial communities were supported.

    The external view of the sintered body for water quality purification which concerns on a sample (No. 6) is shown in FIG. A scanning electron micrograph showing the surface of the water purification sintered body is shown in FIG. FIG. 3 shows a scanning electron micrograph after the surface of the sintered body is loaded with ammonia oxidizing / denitrifying bacterial communities.

  Using the thus obtained microorganism-supported photocatalyst-containing sintered body for water purification (sample No. 6), 10 g of it was mixed with 0.5 mM ammonia nitrogen, 0.5 mM nitrate nitrogen and 10 mM ethanol. Add to a sterilized seawater sample prepared to exist, the effect of nitrogen removal of ammonia-oxidizing / denitrifying bacterial communities supported on such sintered bodies under dark conditions (light-blocked conditions) The results are shown in FIG. As shown in the figure, with the passage of time, ammonium ions and nitrate ions were reduced and the concentration decreased. Along with this, nitrite ions were generated, and it was confirmed that the nitrite ion concentration also decreased with the passage of time. During these processes, the generation of bubbles thought to be nitrogen gas was confirmed.

    In addition, under the same conditions as in the above test example, the nitrogen removal effect of the ammonia-oxidizing / denitrifying bacterial community supported on the sintered body was examined under light irradiation (under black light irradiation), and the results are shown in the figure. As shown in FIG. As shown in the figure, with the passage of time, ammonium ions and nitrate ions were reduced and the concentration decreased. Along with this, nitrite ions were generated, and it was confirmed that the nitrite ion concentration also decreased with the passage of time. However, although the nitrate ion concentration decreased to a low concentration level, about 20% of the ammonium ions remained without being removed. This tendency resulted in some effects of light irradiation and photocatalysis, but nitrogen removal of ammonia-oxidizing / denitrifying bacterial communities carried on the sintered body almost progressed even under light irradiation. I understood.

In addition, the organic substance photocatalytic decomposition effect of the microorganism-supported photocatalyst-containing water purification sintered body in the test example conducted above was examined under dark conditions and under light irradiation (under black light irradiation), and the results are shown in FIG. It is shown in FIG. Under the same conditions as in the test example above, 10 mg / L humic acid was added, and in parallel with the removal of nitrogen from the ammonia-oxidizing / denitrifying bacterial community, the change in concentration in the aqueous humic acid solution over time was investigated. It was. The vertical axis (C / C ₀ ) is (humic acid concentration after elapsed time) / (initial concentration of humic acid), and the concentration of humic acid was measured by absorptiometry (wavelength 400 nm). It is recognized that humic acid is decomposed and purified under light irradiation because the concentration of humic acid is significantly decreased under light irradiation (under black light irradiation) than under dark conditions.

    On the other hand, in order to examine the activation method of the ammonia oxidizing / denitrifying bacterial community supported on the sintered body in the test example conducted above, a carbon-containing organic substance was added as a microorganism activating substance or nutrient. Then, the activation of the ammonia oxidizing / denitrifying bacterial community was investigated. Specifically, in the test example performed above, 10 mM ethanol was added from the beginning, but ethanol was not added from the beginning, but 10 mM ethanol was added 200 hours after the start of nitrogen removal. Then, the activity of ammonia oxidizing / denitrifying bacterial communities was evaluated. FIG. 7 shows the results of investigation under dark conditions (under light-shielded conditions). Then, as shown in the figure, after 200 hours of addition of 10 mM ethanol, the nitrate ion concentration and the ammonium ion concentration were confirmed to decrease rapidly. From this result, it is very effective to supply a carbon-containing organic substance as a microorganism activation substance or nutrient when purifying water using a microorganism-supported photocatalyst-containing water purification sinter. It became clear.

As shown in the above experimental results, in the sintered body for water purification containing a microorganism-supported photocatalyst according to the present invention, ammonia oxidizing / denitrifying bacterial communities act effectively on the sintered body, and the nitrogen removal reaction is effective. The humic acid concentration lowering action based on the photodecomposition action (photocatalytic resolution) of titanium oxide was also observed. Therefore, the microorganism-supported photocatalyst-containing sintered body for water purification according to the present invention is It has become clear that it can be advantageously applied to the purification of water environments such as rivers, swamps, ponds, and oceans.

It is an external view of the sintered body for water purification (sample No. 6) manufactured by the present invention. Sample No. manufactured 6 is a scanning electron micrograph showing the surface of a sintered body according to 6; Sample No. manufactured 6 is a scanning electron micrograph after the ammonia oxidizing / denitrifying bacterial community is supported on the surface of the sintered body according to 6; Purification of water containing microorganism-supported photocatalyst according to the present invention when using a sterilized seawater sample containing ammonia nitrogen at a concentration of 0.5 mM, nitrate nitrogen at a concentration of 0.5 mM and ethanol at 10 mM obtained in the examples It is a graph which shows the result of the nitrogen removal effect | action of the sintered compact for use. Conducted under dark conditions. Purification of water containing microorganism-supported photocatalyst according to the present invention when using a sterilized seawater sample containing ammonia nitrogen at a concentration of 0.5 mM, nitrate nitrogen at a concentration of 0.5 mM and ethanol at 10 mM obtained in the examples It is a graph which shows the result of the nitrogen removal effect | action of the sintered compact for use. Conducted under light irradiation (under black light irradiation). In the case of using a sterilized seawater sample containing ammonia nitrogen at a concentration of 0.5 mM, nitrate nitrogen at a concentration of 0.5 mM, and 10 mM ethanol obtained in the example, 10 mg / L humic acid was added. FIG. 6 is a graph showing the results of the organic substance decomposition action (humic substance decomposition action) of the microorganism-supported photocatalyst-containing water purification sintered body according to the present invention. When the sterilized seawater sample containing ammonia nitrogen at a concentration of 0.5 mM and nitrate nitrogen at a concentration of 0.5 mM was used in the examples, the microorganism-supported photocatalyst-containing sintered body for water purification according to the present invention was used. It is a graph which shows the result of the activation substance and the nutrient substance (carbon containing organic substance) addition effect with respect to nitrogen removal action. After 200 hours, 10 mM ethanol was added. Conducted under dark conditions.

Claims (5)

Composition obtained by blending dredged bottom mud, titanium oxide, and sodium silicate obtained from the bottom of an aqueous system at a ratio of solid content of 43 to 81%, 6 to 17%, and 13 to 46%, respectively. Microorganisms characterized in that a porous structure sintered body obtained by firing slag is loaded with microorganisms for water purification, which are collected from water areas intended for water purification, and decompose water contaminants. A sintered body for water purification containing a supported photocatalyst. The sintered body for water purification according to claim 1, wherein the titanium oxide contains anatase type titanium oxide. The microbial for water purification is a bacterial community composed of a plurality of nitrifying bacteria and denitrifying bacteria, and nitrification reaction and denitrification reaction treatment of water pollutants can be performed simultaneously in parallel. The microorganism-supported photocatalyst-containing water purification sintered body according to claim 2. When the water quality purification sintered body containing a microorganism-supported photocatalyst according to any one of claims 1 to 3 is used to purify the water quality of a target water area, the bottom mud that gives the sintered body is A water purification method for a water area, characterized in that it is dredged mud at the bottom of the water area, and the water purification microorganism is a microorganism collected from the water area. When purifying the water quality of a target water area using the microorganism-supported photocatalyst-containing water purification sintered body according to any one of claims 1 to 4, carbon is used as a microorganism activator or nutrient. A method for purifying water in a water area, comprising supplying an organic substance.

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