JP2000245278A - Production of medium for culturing algae - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mass-producing a culture medium for algae serviceable for solving global environmental problems by culturing a large amount of the algae in the ocean or lakes and marshes, absorbing gaseous carbon dioxide, obtaining a raw material for energy sources from the cultured algae, etc. SOLUTION: A mixture prepared by mixing a raw material containing an industrial waste such as coal ash or an incinerated ash with an inorganic material such as sand, a pulverized shell material or a diatom, a hardening material and a culturing nutrient for algae is molded into a molded product and cured to thereby mass-produce a culture medium for algae capable of floating on water. A cement, water glass, lime, a gypsum, etc., and the culturing nutrient for the algae such as a phosphoric acid compound can be used as the hardening material. A phosphorus component, a nitrogen component and an iron component can be used as the culturing nutrient. The mixture is extrusion molded and molded into a cylindrical form and both ends are closed to thereby make the interior thereof hollow. The apparent specific gravity is reduced to thereby make the molded product floatable on water. The specific gravity of the molded product can be reduced by using a material for reducing the weight. A compression molding method, a method for disintegrating a premolded product after premolding or an agitation molding method can be used. Waste heat of a power generation plant or an incineration furnace can be used as a waste for curing the molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an algae culture medium for cultivating algae on a large scale in oceans and lakes, and in particular, effectively utilizes coal ash and incinerated ash generated from thermal power plants and incinerators. The present invention relates to a production method for producing a large amount of a nutrient supply medium for algae cultivation using sand or crushed shells.

[0002]

BACKGROUND ART microalgae solar utilization rate per unit area, i.e., higher than the CO ₂ to a fixed capacity land plants, the rate of proliferation since also fast, powerful for fixing CO ₂ in the atmosphere Is considered an option. For this reason, for the purpose of preventing global warming, research has been conducted to absorb and fix CO ₂ by microalgae and to produce useful materials such as petroleum alternative fuels using these as raw materials.

For example, a photoreactor capable of concentrating sunlight and irradiating it efficiently is provided, and exhaust gas from a thermal power plant rich in CO ₂ is introduced into the photoreactor.
Research on culturing microalgae is being conducted by many research institutions.

[0004]

In order to fix a huge amount of CO ₂ that contributes to prevention of global warming, it is necessary to culture microalgae over a large area. According to trial calculations, to fix 10% of CO ₂ generated in Japan,
An area of 300 km square is required.

[0005] It is difficult to secure such a vast area in the inland area in Japan, and large-scale cultivation in the ocean is required. However, conventionally, it has been difficult to efficiently supply nutrients in the ocean. Met. That is, when nutrients are sprayed in the ocean, the nutrients rapidly diffuse into the ocean, so that most of the nutrients are not used for algae culture, and the entire ocean becomes eutrophic, causing marine pollution.

For this reason, a medium for fixing nutrients to the sea surface by some method and supplying nutrients in accordance with the growth of algae is required. Earlier, as a result of intensive studies, some of the present inventors have proposed a method for producing a medium that can be suspended in water and can supply nutrients (Japanese Patent Application No. 10-52050).

According to the present invention, it has become possible to produce a medium capable of supplying nutrients for microalgae to grow in the ocean and the like. However, in the invention of Japanese Patent Application No. 10-52050, a large amount of a water repellent was added in order to maintain the suspension in water. Water repellent is one of the raw materials for producing such media.
It is the most expensive, and there is a problem that the water repellent gradually becomes insufficient during long-term floating, and eventually sediments.

The present invention has been made to solve the above-mentioned problems. An object of the present invention is to provide an algae culture medium which is a nucleus for algae growth floating on water, such as coal ash or incineration ash of a thermal power plant. Large-scale and clean growth of algae by providing a large-scale and inexpensive method of producing industrial waste, sand, and shell crushed material, and thereby spreading the mass-produced algae culture medium over a vast sea area. It is possible to do.

[0009]

According to the present invention, a raw material containing an inorganic material, a hardening material and algae culture nutrients is charged into a high-speed stirring blade mixer and mixed to form a mixture, and the mixture is formed. A method for producing an algae culture medium, comprising: a molding step; and a curing step of curing the molded body, wherein the medium is made floatable in water.

In the present invention, in order to make the molded body floatable in water, the molded body has a density of 1 g / cm.
It is particularly preferable to carry out the production so as to be ³ or less.

According to the present invention, a large amount of algae culture medium floating in seawater and freshwater can be produced.

Further, the present invention can use a molding step in which the mixture is charged into a mold and molded, and then the molded body is crushed to form a fine molded body. In this case, curing is performed to an extent suitable for crushing in a stage before forming and crushing after molding in a mold, and further curing can be performed after crushing. According to this method, it is not necessary to put the mixture into the molds one by one, so that a large amount of molded articles can be rapidly manufactured.

In the present invention, in the mixing step, if a high-speed stirring blade mixer having a stirring blade rotating at a high speed in a mixing tank is used, uniform mixing can be performed in a short time, so that it can be preferably used. . And by making the mixed-layer tank a substantially cylindrical shape and disposing the stirring blade at the bottom,
Stirring and mixing can be performed very efficiently. As the stirring blade, a blade type is particularly preferably used because the mixing can be rapidly performed.

Further, in the present invention, as the molding step, a stirring molding step of spraying water or an aqueous solution of a hardening agent while stirring the mixture to form a molded article can be used. This molded body can be cured after molding to increase the strength of the molded body. According to this method, a large number of granular compacts can be molded together.

In the step of spraying water or an aqueous solution of a hardening material while stirring the mixture to form a molded article, a mixer different from the high-speed stirring blade mixer used in the mixing step is prepared and used. Alternatively, the high-speed stirring blade mixer used in the mixing step can be used as it is. By doing so, labor and loss of transfer can be saved. Further, in the present invention, a step of extruding the mixture with a die to form a molded body, for example, by supplying the mixture to an extruder can be used as a molding step. According to this method, a molded article having a predetermined shape can be mass-produced with high productivity.

In the present invention, in the above step of extruding and molding the mixture from the die, the mixture is transferred between the outer wall of the outer tube and the outer wall of the inner tube of the double tube by using a double-tube die. By inserting and compressing and sealing both ends after extrusion, having a porous layer on the outside,
A molded article having a hollow portion therein can be obtained.
Here, the hollow portion is a closed cavity without an entrance. By carrying out the production in this manner, the apparent specific gravity of the molded body can be reduced, which is advantageous for floating on the water surface as an algae culture medium.

Further, in the above step of extruding and molding the mixture from the die, a porous material is interposed between the outermost tube and the intermediate tube of the triple-tube die, and the intermediate tube and the innermost tube are formed. By inserting a material having low water permeability between the porous layer and the hollow portion, by providing a layer having a lower water permeability than the porous layer between the porous layer and the hollow portion, it is possible to prevent the hollow portion from being flooded. Is more stabilized.

The low permeable layer includes coal ash, incineration ash, montmorillonite, kaolinite, cement, water glass,
A material containing at least one of lime and gypsum can be used. By using these, the periphery of the hollow portion can be formed airtight. Since the apparent specific gravity can be reduced by providing a hollow portion, the hollow portion can be made to float in water without containing a lightening material.

Further, in the present invention, as the molding step, a step of compressing the mixture to form a molded body can be used.
According to this method, a molded article having a predetermined shape can be mass-produced with high productivity.

As the inorganic material used in the method for producing an algal medium of the present invention, a material containing at least one selected from coal ash, incinerated ash, sand, ground shells, and diatoms can be preferably used. Of these, coal ash and incinerated ash are particularly preferable because they are industrial wastes generated in large amounts and can be reused.

The inorganic material containing at least one selected from coal ash, incinerated ash, sand, shell crushed material, and diatoms contains components that pollute the environment, that is, components such as heavy metals and harmful organic substances. The reduced or removed one can be preferably used because there is no risk of environmental pollution. Coal ash contains silica and alumina as main components, is relatively stable in composition, and can be used in a controlled manner so as not to include components that pollute the environment. Also, incineration ash can be used after removing components that pollute the environment at the stage of separate collection or the stage of post-treatment of incineration ash.

As the hardening material used in the present invention, those containing at least one selected from cement, water glass, lime, and gypsum are preferably used. As the hardening material containing at least one selected from cement or water glass, an algal culture nutrient, for example, a material containing a phosphate compound can be used as a component thereof.

The culture nutrients for algae used in the present invention preferably contain at least one selected from phosphorus, nitrogen and iron. By including these, it becomes possible to supply nutrients necessary for algae culture.

Further, as the lightening material used in the present invention,
Powdered alumina, perlite, shirasu, shirasu balloon,
Alternatively, those containing at least one selected from granular pumice can be preferably used. By containing these, the specific gravity of the algae culture medium can be reduced, and the medium can be suspended in water.

In the present invention, the amount of the hardening material, the algal culture nutrient, and the weight-reducing material is determined by the weight of the inorganic material.
Preferably, the hardener is at least 5 parts by weight and the algal culture nutrient does not exceed 20 parts by weight, based on 0 parts by weight. If the amount of the hardening material is 5 parts by weight or more, a desired hardness can be obtained.

In the present invention, the mixture may contain a water repellent. This can help stabilize the floating of the algal culture medium on the water surface.

In the mixing step of the present invention, it is preferable to use a high-speed stirring blade mixer in which the bottom of the mixing tank is inclined toward its discharge port as the mixer. The inclination of the bottom improves the discharge of the mixture and improves the productivity.

In the present invention, heat curing can be used as a curing step for curing the molded body. Heat curing at a temperature of 100 ° C. or higher can be preferably used. Further, as a heat source for heating and curing, waste heat of a thermal power plant or a waste incineration plant can be preferably used. If these waste heats are used, there is no need to prepare a new heat source for heat curing, and the waste heats can be effectively used.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below based on examples.

(Example 1) FIG. 1 shows a standard molding process of an algal culture medium in Example 1. For any one of coal ash, incinerated ash, sand and crushed shells as an inorganic material, a hardening material, a lightening material, and algae culture nutrients were added, and water was further added and mixed. The mixing was performed by a Henschel mixer, which is a kind of high-speed stirring blade mixer with a stirring blade, from the viewpoint of making a large amount of material uniform in a short time. FIG. 2 is a schematic cross-sectional view of a Henschel mixer that is a kind of high-speed stirring blade mixer. In FIG. 2, reference numeral 1 denotes a stirring tank, 2 denotes a stirring blade, 3 denotes a lid of the tank, 4 denotes a discharge port, 5 denotes a driving means, and 6 denotes a table.

The mixture thus obtained is placed in a mold and cured (cured while maintaining the temperature and humidity) to produce a molded article.

Subsequently, the molded product was heated and cured (110 ° C., 2 ° C.) in order to accelerate the curing reaction (improve the strength) of the demolded molded product.
4 hours) to produce a pellet-shaped algae culture medium. In the case where the manufactured molded article contains a large amount of alkali and has a high pH, the molded article may be immersed in water as necessary,
H was also lowered. In addition, since it is considered that the inorganic material may contain heavy metals and organic substances that affect the environment, in this test, such heavy metals and organic substances were removed in advance and dried.

Table 1 shows the operating conditions and the results in Example 1. In Table 1, for the production of the algae culture medium molded body, coal ash, incineration ash, sand, and shell crushed materials were used as inorganic materials, sodium silicate was used as a hardening material, pearlite was used as a lightening material, and algae culture was further performed. As nutrients, sodium phosphate, iron phosphate and sodium nitrate were used in a weight ratio of 5: 1: 5.

[0034]

[Table 1]

These molded articles were tested by placing them in a water tank containing seawater containing algae. As shown in Table 1, when any of the inorganic materials was used, sodium silicate was used as a hardening material, and pearlite was used as a lightening material, so that the density of the formed body was 1 g / cm3 or less and the material was suspended in water. And that the growth of algae was obtained.

(Example 2) FIG. 3 shows a process of crushing and forming an algal culture medium in Example 2. Under the same conditions as in Example 1, a hard burden material, a lightening material, algae culture nutrients and water were added to the inorganic material, and the mixture was mixed with a Henschel mixer as a high-speed blade type mixer. The mixture thus obtained was placed in a large mold to prepare a molded product having a size of 300 mm □ × 30 mmt. This is removed from the mold and cured by heating (110 ° C, 2
After 4 hours), the mixture was put into a crushing granulator to obtain a square shaped body having a diameter of about 5 mm. This molded article was tested in the same manner as in Example 1. Table 2 shows the results.

[0037]

[Table 2]

As is clear from Table 2, similarly to the case of the standard molding step, the molded body produced by the crushing molding method was suspended in water at a density of 1 g / cm ³ or less, and the growth of algae was obtained. It was confirmed. According to the present molding method, the number of operations for putting the mixture into the mold can be reduced as compared with the standard method, so that it has become clear that it is advantageous when producing a larger amount of molded articles.

(Embodiment 3) FIG. 4 shows a step of stirring and forming an algal culture medium in Embodiment 3. In the same manner as in Example 1, a hardening material, a lightening material, and algae culture nutrients were added to the inorganic material, and mixed with a Hensiel mixer that was a high-speed blade type mixer. Thereafter, the mixture was agitated by a stirring blade and formed by stirring. Agitation molding is classified into rolling molding and mixed molding as described below according to the speed of stirring by the rotating blades. In the rolling molding method, water was introduced into the powder material mixture while rotating the rotating blades of the mixer at a low speed to obtain a spherical compact having a diameter of about 5 to 15 mm. On the other hand, in the mixing molding method, the powder material mixture is turned into a turbulent state by rotating the rotating blades of the mixer at a high speed, and water is sprayed into the mixture using a spray to supply the powder material mixture.
A 9 mm spherical molded body was obtained. About these moldings,
By supplying steam to the mixer jacket, heat curing (110 ° C., 24 hours) was performed to prepare an algal culture medium.
When the molded body produced in the same manner as in Example 1 contained a large amount of alkali and had a high pH, the pH of the molded body was lowered by immersion in water as needed. Table 3 shows the results.

[0040]

[Table 3]

As is evident from the results in Table 3, the molded body produced by the stirring molding method was suspended in water at a density of 1 g / cm 3 or less and algae were formed in the same manner as when molded and cured by the standard molding process. Was obtained. According to the present molding method, it has been clarified that the algal culture medium can be obtained as a large amount of spherical molded body by changing the size of the mixer according to the required amount of the molded body. Further, as is apparent from the present example, it was also found that according to the present molding method, the steps of mixing and molding the materials and the steps of heat curing can be performed in the same mixer. However, of course, each step may be performed independently by a rolling molding method using a drum type or bread type granulator dedicated to the molding step, or a mixed molding method using a flexomix apparatus.

Example 4 FIG. 5 shows an extrusion process of an algal culture medium in Example 4. Under the same conditions as in Example 1, a hardening material, a lightening material, algae culture nutrients, and water were added to the inorganic material, and mixed with a Henschel mixer.
The mixture thus obtained was supplied to a screw-type extrusion granulator to produce a columnar molded body having a diameter of about 10 mm and a length of about 10 mm. The molded body is cured by heating (110 ° C., 24
Time) to produce an algal culture medium. Table 4 shows the results.

[0043]

[Table 4]

When the molded article produced in the same manner as in Example 1 contains a large amount of alkali and has a high pH, it was immersed in water to lower the pH of the molded article, if necessary. As is evident from the results in Table 4, similarly to the case where the molded article produced by extrusion molding was molded and cured in the standard molding step, the molded article was suspended in water at a density of 1 g / cm ³ or less, and the growth of algae was obtained. It was confirmed.

(Embodiment 5) FIG. 6 shows a compression molding step of an algal culture medium in Embodiment 5. Under the same conditions as in Example 1, a hardening material, a lightening material, algae culture nutrients, and water were added to the inorganic material, and mixed with a Henschel mixer.
The mixture thus obtained was supplied to a hydraulic compression granulator to produce a columnar compact having a diameter of about 10 mm and a length of about 10 mm. This molded body is cured by heating (110 ° C, 24 hours)
Thus, an algal culture medium was prepared. When the molded body produced in the same manner as in Example 1 contained a large amount of alkali and had a high pH, the pH of the molded body was lowered by immersion in water as needed. Table 5 shows the results.

[0046]

[Table 5]

As is evident from the results in Table 5, the molded body produced by the compression molding method was floated in water at a density of 1 g / cm 3 or less in the same manner as when molded and cured in the standard molding step.
It was confirmed that the growth of algae was obtained.

Example 6 A test was performed in the same manner as in the above example, except that the inorganic material was limited to coal ash, and the curing material was changed in various ways. Table 6 shows the results.

[0049]

[Table 6]

As is clear from Table 6, as the curing material,
When sodium silicate, potassium silicate, lithium silicate, and silica sol were used in addition to the cement, it was confirmed that a molded article floating in water and capable of obtaining algae growth, that is, an algae culture medium was obtained.

Tests were conducted in the same manner as in Examples 2 to 5 except that the hardening material was limited to cement and sodium silicate, and the influence of the difference in the molding method was also confirmed. The obtained results were almost the same as those obtained by the standard molding process. The molded product was suspended in water at a density of 1 g / cm ³ or less, and the growth of algae was confirmed. From these results, in any of the molding steps of the inorganic material in the present invention, that is, standard molding, crushing molding, stirring molding (rolling molding, mixing molding), extrusion molding, and compression molding, any molding agent can be subjected to standard molding. It was confirmed that an algal culture medium capable of obtaining the same results as in the case of the step can be produced.

(Example 7) A phosphate compound which is also effective as a nutrient for algae culture was used as a hardening material. As other algae culture nutrients, a molded product of an algae culture medium containing iron phosphate or iron hydroxide oxide (iron content) and sodium nitrate (nitrogen content) was prepared. Table 7 shows the results.

[Table 7]

As is clear from these results, sodium phosphate, sodium dihydrogen phosphate, aluminum phosphate and aluminum hydrogen phosphate are all effective as hard burrs in the standard molding method. When used, it was confirmed that a molded article floating in water and capable of obtaining algae growth could be produced.

The conditions in which sodium phosphate and aluminum phosphate were respectively added as phosphates were as follows:
Tests were performed in the same manner as in Examples 2 to 5 above, and the influence of the difference in the molding process was also confirmed. As a result, the obtained results were almost the same as those in the case of the standard molding method. The molded body was suspended in water at a density of 1 g / cm ³ or less, and the growth of algae was confirmed. From these results, it can be seen that the method for forming an inorganic material according to the present invention, ie, the standard molding step, the crushing molding step, the stirring molding step (rolling molding step, the mixing molding step), the extrusion molding step, and the compression molding step, shows that It was confirmed that a phosphate compound that is also effective as a culture nutrient can be applied as a hardening material.

FIG. 7 shows the change in the compressive strength of the formed molded body when the amount of the hardening material was changed under the conditions of Examples 6-1 and 6-2 and 7-1. The results are shown. From this result, it was found that the strength satisfies the reference value when the hardening material is 5 parts by weight or more with respect to 100 parts by weight of the inorganic material.

FIG. 8 also shows the result of confirming the influence of the difference in the molding process when fixing to sodium silicate as a hardening material. From these results, it was found that there was no significant change in the strength due to the difference in the molding process, and that the hardening material satisfies the reference value of the strength at 5 parts by weight or more.

Example 8 Algae cultivation was carried out under the same standard molding conditions as in Example 1, except that the inorganic material was limited to coal ash, the hardening material was limited to sodium silicate, and the algal culture nutrients were variously changed. A medium was manufactured and tested in the same manner as in Example 1. Table 8 shows the results.

[0058]

[Table 8]

As is clear from Table 8, when iron phosphate, iron hydroxide oxide, aluminum phosphate, and sodium phosphate are used as nutrients for algae culture, the algae floating in water and capable of growing algae are obtained. It was confirmed that a culture medium was obtained.

The above-mentioned procedure was carried out in the case where iron phosphate and iron oxide (iron), aluminum phosphate and sodium phosphate (phosphorus), and further sodium nitrate (nitrogen) were added as algal culture nutrients. Tests were conducted in the same manner as in Examples 2 to 5, and the results of examining the effects of the differences in the molding steps are also shown in Table 8. As is clear from these results, all of the obtained molded articles were almost the same as those in the standard molding step, and the molded articles were suspended in water at a density of 1 g / cm3 or less, and the growth of algae was confirmed. from this result,
Regardless of the difference in the molding process, the effect of adding algae culture nutrients was confirmed.

FIG. 9 shows the results of examining the change in algal growth rate when the amount of iron phosphate + sodium phosphate + sodium nitrate, which is the nutrient for algal culture, was changed under the conditions of Example 8-1. . From FIG. 9, it can be seen that if the algal culture nutrient is 20 parts by weight or less with respect to 100 parts by weight of the inorganic material, the algal growth rate is not saturated with respect to the increase in the algal culture nutrient, and the amount is appropriate as the addition amount. .

(Example 9) An algae culture medium molded body was produced in the same standard molding step as in Example 1 except that the inorganic material was limited to coal ash and the hardening material was limited to sodium silicate. A test was conducted to examine the effectiveness of various lightening materials. Table 9 shows the results. From these results, in addition to pearlite, Shirasu and its compounds, granular pumice, and by using a mixture of these, floating in water, and,
It was confirmed that an algal culture medium molded body capable of obtaining algae growth was obtained. Table 9 also shows the results of tests performed on the conditions in which pearlite and shirasu were added as weight-reducing materials, in the same manner as in Examples 2 to 5 above, and the effects of the differences in the molding steps were confirmed. .

[0063]

[Table 9]

As is evident from the results, all of the obtained molded articles were almost equivalent to those in the standard molding step.
The molded product was suspended in water at a density of 1 g / cm ³ or less, and the growth of algae was confirmed. From these results, it was confirmed that the effect of adding the lightening material was obtained regardless of the difference in the molding process.

FIG. 10 shows the above embodiments 9-2, 9-3,
The results obtained by examining the change in density of the molded body when the addition amount of pearlite, shirasu and powdered aluminum, which are lightening materials, were changed under the respective conditions of 9 and 9-5. From these results, it was found that by adding 10 parts by weight or more of the weight-reducing material to 100 parts by weight of the inorganic material, the density of the formed body could be made 1 g / cm3 or less, and the formed body could be suspended in water.

FIG. 11 shows the results obtained by confirming the influence of the difference in the molding process when pearlite was used as the lightening material. From these results, no significant change in the density of the molded body due to the difference in the molding process was observed. In any case, when the weight-reducing material was 10 parts by weight or more, the standard value was 1 g / cm.
It was found that the density was ³ or less.

(Embodiment 10) Under the same conditions as in RUN 1-1 of Embodiment 1 above, the effect of the different mixers on the mixing step of mixing the coal ash with the hardening material, the lightening material, the algal culture nutrients, and the water. Was examined. The volume of the mixing tank was 20 L (liter), and the amount of the mixture was 10 L. The mixers are a high-speed stirring blade mixer having a peripheral speed of 5 m / sec or more, a high-speed blade mixer used at a peripheral speed of 5 m / sec, and a medium-speed blade mixer used at a peripheral speed of 5 m / sec. About Figure 2
And a standard type shown in FIG. 12 and a type in which the bottom of the mixing tank of the high-speed stirring blade mixer whose schematic sectional view is shown in FIG.
Further, for comparison with these blade types, a case where a low-speed wheel type mixer was used was also performed. Here, in the high-speed stirring blade mixer of FIG.
Is a stirring blade, 3 is a lid of a tank, 4 is an outlet, 5 is a driving means,
6 is the platform and 7 is the inclined bottom of the stirred tank.

Table 10 shows the results. The high-speed blade-type and medium-speed mixers produced a mixed mixture in 5 minutes, whereas the wheel-type mixers required more than 30 minutes, and the mixing was uneven and agglomerated. Lumps were seen.

[0069]

[Table 10]

The mixture was discharged from the mixer, and the discharge rate was calculated from the discharge weight and the input weight. As a result, the discharge rate of the standard type was 95% by weight in both the high-speed and medium-speed blade mixers. In contrast, the discharge rate of the type in which the bottom of the mixing tank is inclined toward the discharge port is 9
It was 9.5% by weight. This is considered to be because the standard type is capable of discharging the mixture by its own weight, while the mixture remaining in the clearance portion below the rotary blade is not extruded, but the discharge rate is extremely high. On the other hand, in the wheel type, the mass was fixed to the rotating blades and the like, and the discharge rate was low, and was 80% by weight.

Subsequently, 10 L of water was added to the mixing tank, and the mixture was rotated for 1 minute. After that, the washing water was discharged, and the washing condition was visually checked. As a result, the high-speed blade mixer was successfully cleaned. However, in the standard type, cleaning water remained in the clearance below the rotating blades. On the other hand, in the medium-speed blade type mixer, a small amount of the mixture remained so as to stick to the wall surface of the mixing tank and the surface of the rotating blade. For this reason, when an attempt was made to spray high-pressure water of about 5 MPa, washing was successfully performed. With respect to the wheel mixer, a considerable amount of the mixture remained even after the initial washing, and was not completely removed even by spraying high-pressure water.

From the above results, a high-speed stirring blade mixer and a high-speed blade-type mixer, which are high-speed stirring blade mixers, are suitable for uniformly mixing a large amount of a mixture in a short time. It was confirmed that the type in which the bottom of the mixing tank was inclined toward the discharge port was particularly preferable from the viewpoint of dischargeability and cleanability.

(Example 11) One example of an extrusion molding method for producing a molded article having a hollow portion inside the present invention is shown in FIG.
3 will be described. In this example, the hardening material was added to the inorganic material (coal ash) in the same composition as in Example 4 except that the weight reduction material was not included in the extrusion molding process shown in Example 4.
(Sodium silicate), algae culture nutrients (sodium phosphate, iron phosphate, sodium nitrate) and water are added, mixed by a high-speed blade mixer, molded by an extruder, and cured at 110 ° C. for 24 hours Thus, a molded article having a hollow portion inside the molded article was produced. In this embodiment, first, a mixture of the raw materials of the porous layer 13 is inserted between the outer tube 11 and the inner tube 12 of the double tube, and formed into a cylindrical shape by extrusion. This was pressed against both ends of the extruded body by a compressor 14 to produce a formed body having a hollow portion 15 inside. The size of the compact was such that the diameter of the hollow portion was about 2 mm, the outer diameter of the porous layer was about 5 mm, and the length of the compact was about 1 cm. The number of days of floating of the molded article according to this example in water was about 200 days.

Next, an example of a method for forming a molded article having a hollow portion and a low water-permeable layer inside the molded article will be described with reference to FIG.
This will be described with reference to FIG. 14, the same parts as those in FIG. 13 are given the same numbers. In the embodiment shown with reference to FIG. 13 described above, when water that has permeated the molded body enters the hollow portion, when the water accumulates in the hollow portion, the molded body sinks. However, in this embodiment shown with reference to FIG. 14, in order to form the low water-permeable layer 6, a porous material is provided between the outermost tube and the intermediate tube of the triple-tube die. A material having low water permeability is put between the middle tube and the innermost tube, and is formed into a cylindrical shape by extrusion. For the low permeable layer 6, at least one of coal ash, incineration ash, montmorillonite, kaolinite, cement, water glass, lime, and gypsum is used. In this embodiment, the hollow portion has a diameter of 2 mm, a low water-permeable layer of 1 mm, a porous layer outer diameter of about 6 mm, and a molded body length of about 1 c.
m, and the other steps were the same as those in FIG. With such a structure, the water that has passed through the porous layer has a low water-permeable layer, and the permeation rate is significantly reduced. Therefore, the water must be suspended in the water for a period that can supply nutrients for aqueous organisms such as microalgae. Turned out to be possible.

The floating period of the molded body according to the present embodiment in water has passed one year, and is still floating.

(Example 12) The progress of the curing of the molded article formed by the same standard molding step as in Example 1 was measured for each of the cases of curing by heating when curing and curing by heating in steam. Examined. Table 11 shows the results.

[0077]

[Table 11]

From the above results, it was found that the curing time was increased and the production time was shortened in the case of heat curing and in the case of heat curing in steam as compared with the case where these measures were not taken. Table 11 also shows the results of tests performed in the same manner as in Examples 2 to 5 above, and the effects of differences in molding methods were confirmed. As is clear from these results, regardless of the difference in the molding method, when heated to 100 ° C. or more, the composition was cured within one day, and it was confirmed that the production time was shortened. Further, in this embodiment, the steam of the once-through boiler is used. However, when providing a molding facility in a thermal power plant or a waste incineration plant, it is cost-effective to utilize this waste heat.

The above embodiments shown in the present invention are merely examples, and do not limit the present invention. The scope of the invention is indicated by the claims, and all the modifications included in the contents of the claims are included in the present invention.

[0080]

According to the method of the present invention for producing an algae culture medium using an inorganic material as a main raw material, a molded body capable of floating and growing algae by floating on a water surface such as a sea surface can be produced in a short time. It can be manufactured in large quantities and at low cost. By effectively utilizing industrial waste such as coal ash and incinerated ash as the main raw material, and spraying it onto the ocean as a culture medium for algae, eutrophication and pollution of the ocean can be prevented to prevent algae Can be cultured in large quantities, which can contribute to the prevention of global warming by reducing CO ₂ in the atmosphere. Also,
The cultured algae can be used as a raw material of an effective substance such as alcohol, and can contribute to supply of alternative energy to fossil fuels and the like. Therefore, the present invention will greatly contribute to solving future environmental and energy problems for humankind.

[Brief description of the drawings]

FIG. 1 is a flowchart of a manufacturing process of an algae culture medium using an inorganic material as a main raw material according to a standard molding method described in Example 1.

FIG. 2 is a schematic cross-sectional view of a Henschel mixer that is a high-speed stirring blade mixer in a process of manufacturing an algal culture medium described in Example 1.

FIG. 3 shows a flowchart of a manufacturing process of an algae culture medium using an inorganic material as a main raw material by the crushing and molding method described in Example 2.

FIG. 4 shows a flowchart of a molding step of an algae culture medium using an inorganic material as a main raw material by the stirring and mixing molding method described in Example 3.

FIG. 5 shows a flowchart of a process for producing an algae culture medium using an inorganic material as a main raw material by the extrusion molding method described in Example 4.

FIG. 6 is a view showing a production process of an algae culture medium using an inorganic material as a main raw material by the compression molding method described in Example 5.

FIG. 7 shows the relationship between the amount of hardener added and the strength of the algal culture medium in the algal culture medium according to the standard molding method described in Example 7.

8 shows the relationship between the amount of hardener added and the strength of the algal culture medium in the various molding methods described in Example 7. FIG.

FIG. 9 shows the relationship between the amount of nutrient / supplement added and the growth rate of algae in the algae culture medium described in Example 8.

FIG. 10 shows the relationship between the amount of lightening material added and the algal culture medium density in the standard molding method described in Example 9.

FIG. 11 shows the relationship between the amount of the weight-reducing material added and the density of the algal culture medium in the various molding methods described in Example 9.

FIG. 12 is a schematic cross-sectional view of a Henschel mixer in which the bottom of a mixing tank is inclined toward an exhaust port in a step of manufacturing an algal culture medium described in Example 10.

FIG. 13 is a diagram schematically showing an outline of an extrusion molding method for producing a molded article having a hollow portion therein described in Example 11.

FIG. 14 is a diagram schematically illustrating an outline of an extrusion molding method for producing a molded body having a hollow portion and a low water-permeable layer inside described in Example 11.

[Explanation of symbols]

1 stirrer tank 2 stirrer blade 3 tank lid 4 discharge outlet 5 drive source 6 table
7 ... bottom part, 11 ... outer pipe, 12 ... inner pipe, 12 '... middle pipe, 13 ... porous layer, 14 ... compressor, 15 ... hole part, 16
…… Low permeable layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinya Miyamoto 1 Kawasaki City, Kanagawa Prefecture, Komukai Toshiba-cho, Kawasaki City, Kanagawa Prefecture 1 Toshiba R & D Center Co., Ltd. (72) Inventor Naomi Toyohara Kawasaki, Kanagawa Prefecture 1 Toshiba, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Pref.Toshiba R & D Center Co., Ltd. (72) Inventor Yu Okamoto 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. Inventor Yoshinari Takamatsu 66-2 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Engineering Corporation

Claims (20)

[Claims] 1. A method comprising the steps of: mixing a raw material containing an inorganic material, a hardening material, and algae culture nutrients into a mixture, forming the mixture into a molded body, and curing the molded body. A method for producing an algae culture medium, which is capable of floating in water. 2. The method for producing an algae culture medium according to claim 1, wherein the forming step includes a step of charging the mixture into a mold to form a preformed body, and a step of crushing the preformed body. And a crushing and forming step of forming a finely formed body by using the method. 3. The method for producing an algae culture medium according to claim 1, wherein a high-speed rotary wing mixer is used in the mixing step, and water or a hardener aqueous solution is sprayed while stirring the mixture in the molding step. A method for producing an algal culture medium, comprising a stirring molding step of molding into a molded article. 4. The method for producing an algae culture medium according to claim 3, wherein the stirring and forming step is performed in the same high-speed stirring blade mixer as in the mixing step. 5. The method for producing an algal culture medium according to claim 1, wherein the molding step includes an extrusion step of transferring the mixture to a die and extruding the mixture to form a molded body. A method for producing a culture medium. 6. The method for producing an algae culture medium according to claim 5, wherein in the extrusion forming step, the die is a double-tube die, and the inner and outer walls of the outer tube of the double-tube die are formed. This step is a step of transferring and putting the mixture between the outer wall of the pipe and extruding the mixture and compressing and sealing both ends thereof to form a molded body having a porous layer on the outside and a hollow portion inside. A method for producing an algae culture medium, comprising: 7. The method for producing an algae culture medium according to claim 6, further comprising a step of providing a layer having a lower water permeability than the porous layer between the porous layer and the hollow portion. A method for producing an algal culture medium. 8. The method for producing an algae culture medium according to claim 7, wherein a porous material is provided between an outermost tube and an inner tube of a triple-tube die, and a tube is provided in the middle of the dice. A method for producing an algae culture medium, characterized in that a low water-permeable material is put between a tube and an innermost tube, extrusion-molded, and both ends are compressed and sealed. 9. The method for producing an algal culture medium according to claim 8, wherein the low water-permeable layer is made of clayey montmorillonite, kaolinite, cement, water glass, lime,
A method for producing an algal culture medium, comprising at least one of gypsum and gypsum. 10. The method for producing an algal culture medium according to claim 1, wherein the molding step includes a compression molding step of compressing the mixture to form a molded body. 11. The method for producing an algal culture medium according to claim 1, wherein the inorganic material is at least one selected from coal ash, incinerated ash, sand, ground shells, and diatoms. A method for producing an algal culture medium, comprising: 12. The method for producing an algal culture medium according to claim 11, wherein the inorganic material has been subjected to a treatment for reducing or removing components that pollute the environment. 13. The method for producing an algal culture medium according to any one of claims 1 to 12, wherein the hardening material comprises:
A method for producing an algal culture medium, comprising at least one selected from cement, water glass, lime, and gypsum. 14. The method for producing an algae culture medium according to claim 13, wherein the hardening material contains algae culture nutrients as a constituent. 15. The method for producing an algal culture medium according to any one of claims 1 to 14, wherein the algal culture nutrient contains at least one selected from a phosphorus content, a nitrogen content, and an iron content. A method for producing an algae culture medium. 16. The method for producing an algal culture medium according to claim 1, wherein the hardening material, the algal culture nutrient, and the lightening material are added in an amount of 100% by weight of the inorganic material. Parts by weight of said hardening material and at least 20 parts by weight of said algal culture nutrient per part by weight. 17. The method for producing an algae culture medium according to any one of claims 1 to 16, wherein, as a mixer used in the mixing step, a high-speed stirring blade mixer having a mixing tank bottom inclined toward an outlet. A method for producing an algae culture medium, comprising using a machine. 18. The method for producing an algae culture medium according to claim 1, wherein the curing step of curing the molded body is heat curing at a temperature of 100 ° C. or higher. A method for producing a culture medium. 19. The method for producing an algae culture medium according to claim 1, wherein the curing step includes a heat curing step, and the heat source of the heat curing is a thermal power plant or a waste incineration plant. A method for producing an algae culture medium, characterized in that the heat is waste heat. 20. The method for producing an algal culture medium according to claim 1, wherein the raw material further comprises a lightening material.