JPH0434479B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention is directed to a porous purification material for fish and shellfish habitats, which is used to purify water inhabited by fish and shellfish, for example, water in fish tanks where microorganisms or algae grow. It is related to. <Problems to be solved by the prior art and the invention> When raising fish in an aquarium, organic matter derived from food residue and fish excrement, as well as nitrogen and phosphorus generated by the decomposition of the organic matter, accumulate in the aquarium and drain the water. It not only pollutes the water, but also causes the growth of microorganisms and algae. If microorganisms or algae occur, the water in the aquarium will be deficient in oxygen or in excess of oxygen, and the fish kept in the aquarium will die. Therefore, in order to solve this problem,
Generally, a technique is employed in which a water filtration device is installed in an aquarium and the water is circulated and filtered. Although this technology has shown considerable effectiveness, it not only requires constant operation and management of the device;
There is a problem in that there is a limit to the purifying ability of activated carbon, Bakhan stone, etc., which are used as filtering materials built into the device. Also known is a method for producing a porous purifying material (Japanese Patent Application Laid-open No. 48746/1983) in which a shaped article made by mixing zeolite as the main material with a foaming material and a binder is foamed and dried. However, zeolite, which is the main material of this invention, has a pH value in water areas where fish and shellfish live.
There is no effect of suppressing changes in pH, that is, a PH buffering effect, and there is no effect of removing phosphorus. Therefore, the present invention provides a porous material that purifies water bodies in water areas where fish and shellfish live by removing organic matter derived from feed residue and excrement excreted by fish and shellfish, as well as nitrogen and phosphorus generated by the decomposition of these organic substances. The purpose is to provide purification materials. <Means for Solving the Problems> The present invention involves adding a foaming agent to an aqueous slurry mainly composed of silicic raw materials and calcareous raw materials, and then foaming and curing the resulting cured product, which is subjected to a hydrothermal reaction at high temperature and high pressure. The above-mentioned problem is solved by providing a porous purifying material for fish and shellfish habitat water bodies, which is obtained by processing and has tobermorite as a main component and has a vacancy rate of 50 to 90%. Here, the operation of the present invention will be explained. In waters where fish and shellfish live, the water is oxidized by fish and shellfish excrement and uneaten food, causing water rot. In such an environment, the vitality of the fish and shellfish that live there declines, making them more susceptible to disease. A decrease in pH can be cited as an indicator of water oxidation. It is extremely important for the survival of seafood to keep this PH oxidation low and maintain an environment suitable for fish farming for a long time. Therefore, when the specific tobermorite according to the present invention is poured into the water, the PH buffering effect of tobermorite, which is the main component of the porous purifying material, suppresses the drop in the pH of the water and removes dirt on the porous surface. Some of the causative substances, such as ammonia, are adsorbed, and as a result, pollution of the water inhabited by seafood is suppressed. Furthermore, when the porous purifying material is left in water, microorganisms also begin to inhabit its pores. Among these microorganisms, there are also microorganisms that decompose organic matter, so these microorganisms decompose the organic matter, which is a source of water contamination, and convert it into water and carbon dioxide, thereby maintaining an aquatic environment where fish and shellfish can live. Furthermore, for example, ammonia in water bodies is generated from fish excreta, decomposed leftover feed, urine, and other excreta. When fish and shellfish that live in such water bodies absorb ammonia, the gill tissues and gill capillaries are affected, leading to respiratory failure and weakness. Nitrite is produced when this ammonia is oxidized by the action of microorganisms, but this nitrite is highly toxic to seafood, making it impossible for hemoglobin in the blood to combine with oxygen, resulting in methemoglobinopathies. . Since the porous purifying material of the present invention has the effect of promoting nitrification of ammonia, ammonia changes to nitric acid via nitrous acid. It is said that nitric acid in the sewage water area inhabited by fish and shellfish, to which the present invention is applied, has almost no toxicity to fish and shellfish ("Freshwater Fish Culture and Water Fish", p. 88, Japan Society of Fisheries Science, 1981). Nitrification is extremely important for aquatic environments where fish and shellfish live. Furthermore, if a large amount of phosphoric acid accumulates in a water area where fish and shellfish live, large amounts of blue-green algae are likely to occur in the water area. If blue-green algae grows in a moderate and stable amount, it will create a very good environment for fish and shellfish to live in, but when it occurs in large numbers, it threatens the habitat of fish and shellfish. When the tobermorite according to the present invention is introduced into a water area in the aquaculture field where fish and shellfish live, phosphoric acid from the residue of the feed given to the fish and the excrement of the fish and shellfish that have eaten the feed is supplied from the surface of the porous purifying material. It reacts with calcium ions (Ca ²⁺ ) that are present, and is crystallized in the form of calcium hydroxyapatite. In this way, phosphate ions in the water are crystallized and removed, and the growth of algae is suppressed. Moreover, since the calcium ions are supplied from the surface of the porous purifying material, phosphoric acid is appropriately crystallized and removed, and algae such as blue-green algae are always in a stable breeding state. The action of such a porous purifying material depends on its vacancy.
The porosity of the porous purifying material used in the present invention is 50 to 90%, preferably 60 to 90%.
80% is good. This is because when the vacancy rate is less than 50%, the specific surface area is small, making it difficult for microorganisms to settle on it, and the phosphorus removal rate is low, making it less effective in providing a good environment for fish. This is because it causes floating on the surface of the water, which is undesirable. Hereinafter, the configuration of the present invention will be explained in detail. More specifically, the porous purifying material according to the present invention can be produced by adding a foaming agent such as aluminum powder to a water slurry whose main raw materials are silicic raw materials and calcareous raw materials, and then watering the slurry with foaming agent such as aluminum powder under high temperature and high pressure. Molded products whose main component is tobermorite obtained by thermal reaction treatment,
Alternatively, a crushed product obtained by crushing this molded product has a void ratio of 50 to 90%. The tobermorite is obtained by curing silicic raw materials and calcareous raw materials at a predetermined CaO/SiO ₂ molar ratio (approximately 0.5 to 2.0) in an autoclave at high temperature and high pressure under the required pressure and temperature according to a conventional method. It will be done. Examples of siliceous raw materials include powders such as silica stone, silica sand, cristobalite, amorphous silica, diatomaceous earth, ferrosilicon dust, and white clay, and examples of calcareous raw materials include powders such as quicklime, slaked lime, and cement.
Tobermorite obtained in this way is weakly alkaline, has high PH buffering ability, and has a specific surface area of 20 to 400.
It is particularly preferable because it has a large value of m ² /g. The porous purifying material according to the present invention has a porosity of 50 to 90%, but when this porosity is obtained during the production of tobermorite, a foaming agent is added to a water slurry of silicic raw materials and calcareous raw materials. After adding a foaming agent such as a metal foaming agent such as aluminum powder or a foaming agent such as an AE agent, a hydrothermal reaction treatment may be performed at high temperature and high pressure. Here, the metal foaming agent generates gas through a chemical reaction, and its usage ratio varies depending on the amount of bubbles and water entrained in the water slurry, but can be derived from the chemical reaction equation. Specific examples of foaming agents include resin soaps, saponins, synthetic surfactants, hydrolyzed proteins, and polymeric surfactants, which mainly introduce air bubbles physically through surfactant action. In some cases, foam is created by simply mixing and stirring raw materials, and in other cases, stable foam is created using a special stirring tank or foaming device.
This foam may be volumetrically measured and mixed into the raw material. When using such a foaming agent, it is necessary to test the stability of the foam and then determine the amount to be added. Further, here, as the powdered tobermorite, a powder obtained by crushing a molded product with voids in it as described above may be used. In addition, when using a porous purification material with a high porosity,
It is better to use formwork molding. When using porous purification materials manufactured in this way in an aquarium, the tobermorite that makes up the material is weakly alkaline, so the pH level of the water
may be increased to about 9. In this case, a part of the surface of this porous purifying material can be neutralized before use. This neutralization treatment can be easily carried out by leaving the porous purifying material in a carbon dioxide atmosphere. However, if the calcium carbonate (CaCO ₃ ) content exceeds 30% by weight as a result of this neutralization treatment, tobermorite will break down its crystals and easily dissolve into water, resulting in the loss of water in the aquarium.
The neutralization process must be carried out so that the CaCO ₃ content does not exceed 30% by weight, as this not only makes it easier for the pH to rise, but also shortens the duration of water purification performance. Simply by immersing such a porous purifying material in an aquarium, the water in the aquarium is purified. In this case, the porous purifying material may be placed in a mesh bag or may be used as is by being submerged at the bottom of the tank. It may also be used by filling it into an environmental filtration device. When the porous purification material according to the present invention is used to purify a fish tank, it is possible to remove substances that are inconvenient for fish habitat, such as food scraps and fish excrement.
By suppressing changes in pH and decomposing organic matter, nitrifying ammonia, and crystallizing phosphoric acid contained in these substances, it maintains a clear state that is excellent for seafood to live in for a long time. maintained over time. If the porous purification material according to the present invention has been used for a long period of time and its purification effect has decreased, the surface of the purification material can be washed with water to remove the enlarged and aged biofilm, and then used again. becomes possible. Next, an example of manufacturing the porous purifying material according to the present invention will be shown. (Manufacturing example of porous purification material) (1) Tobermorite purification material 5 parts by weight of silica powder, 2 parts by weight of quicklime powder, and 3 parts by weight of ordinary Portland cement (CaO/
_SiO2 molar ratio = 0.8) to metallic aluminum powder
A slurry was prepared by adding 7 parts by weight of water to the mixture obtained by adding 0.008 parts by weight. This slurry was poured into a mold, left to stand for 4 hours, and then removed from the mold, which was then hydrothermally treated in an autoclave at 180° C. and under 10 atmospheric pressure for 10 hours. The obtained molded product was crushed using a crusher and sieved to a particle size of 5 to 10 mm. Thereafter, a portion of the surface was carbonated by leaving it in a container filled with carbon dioxide gas for 4 hours, and the resulting material was washed with water and used as a porous purifying material. The emptiness rate of this purification material is 75
%, and the CaCO ₃ content was 5.2%. (2) Tobermorite purification materials having various vacancies In the production method shown above, various tobermorite purification materials were obtained by changing the addition ratios of metal aluminum powder and water as shown in Table 1.

[Table] (3) Tobermorite purification materials with various CaCO ₃ contents In the production method shown in (2) above, the treatment time in a container filled with carbon dioxide gas is varied as shown in Table 2. As a result, various tobermorite purification materials were obtained.

[Table] <Examples> Example 1 A plastic water tank (30 x 16 x 22 cm) containing 500 c.c. of various porous purifying materials was injected with 9 tap water that had been kept for a day and a night. Place 10 goldfish (Japanese goldfish, 14 to 6 cm long) in each of these aquariums, leave them indoors in a place that usually receives several hours of direct sunlight per day for about two months from early March, and add the same amount of commercially available goldfish to each tank. Goldfish were raised by feeding them and sending air at 500 c.c./min using a commercially available air pump. In addition, a constant amount of water was added to the evaporated water. The material using the various porous purifying materials produced in the above production example is referred to as A, and for comparison, commercially available pebble gravel, Bakhan stone, and limestone (all with particle sizes of 5 to 5
B-1, B-
2. It was set as B-3. Regarding these, the water condition in the aquarium and the ecology of the goldfish were observed. The results are shown in Table 3.

【table】

[Table] As a result, goldfish died in about 2 months using pebble gravel, Bakhan stone, and limestone used as comparative examples, whereas goldfish containing the porous purifying material of the present invention had an extremely high survival rate. It was hot. This is because in the comparative example, many microorganisms were observed in the tank from around the 20th day, and from around the 25th day, algae began to grow rapidly and visibility became poor, making observation from the outside difficult. After that, goldfish died one by one from diseases such as fluke disease, which causes white spots on the skin, and water mold disease, which causes a white film to appear on the goldfish's skin. On the other hand, in the case containing the porous purification material of the present invention, algae began to grow on the walls of the tank from around 40 days onwards, and although some were floating inside the tank,
As in the comparative example, there were very few airborne microorganisms, and there was no outbreak of the above-mentioned diseases in goldfish. In addition, compared to the comparative example, in the present invention, the change in pH was small, the amount of dissolved nitrogen and phosphorus was low, and a favorable environment for fish farming was maintained for a long time. Example 2 In the same manner as in Example 1, the differences in effectiveness of the five types of porous purifying materials having different porosity produced in Production Example (2) above were tested. The test period will be one month from early May, and the test period will be one month from early May.
After several months, the survival rate of the goldfish, the water quality, the state of suspended microorganisms, and the time of algae outbreak were observed. The results are shown in Table 4.

[Table]: Normal appearance +: Slight appearance As shown in Table 4, the vacancy rate of porous purification material is greatly involved in the settlement of microorganisms and decomposition of organic matter, % or less, the number of floating microorganisms in the aquarium increased, algae grew faster, the water quality deteriorated, and the survival rate of goldfish was low. Example 3 In the same manner as in Example 1, the six types of porous purifying materials produced in Production Example (3) above and having different states of carbonation were tested for differences in effectiveness. The test period was one month from early June, and after one month, the survival rate of goldfish, water quality, state of suspended microorganisms, and period of algae growth were observed. The results are shown in Table 5.

[Table]: Moderate appearance +: Slight appearance As shown in Table 5, the purification ability of the products that had been neutralized for 192 hours was lower than that of the others. This material has a high calcium carbonate content of 36.2%, which is thought to be due to the tobermorite crystals breaking down and completely covering the surface. Therefore, in the case of neutralization treatment, it is preferable that the CaCO ₃ content is 30% or less. Example 4 First, 0.2 g each of tobermorite and theolite were added to 150 ml of water whose pH was adjusted to 4 or less. As shown in Figure 1, water with tobermorite added
The PH gradually increased, and the result was a good PH value exceeding PH6, the lower limit at which living things can live healthily. On the other hand, although the pH of the zeolite-added water rose slightly immediately after it was added, no change was observed after that, and the pH never exceeded the lower limit of 6, at which living organisms can live healthily. Next, 10 mg each of tobermorite and zeolite were added to 500 ml of water with a pH of 7, and 0.05 ml of hydrochloric acid was added thereto. As shown in Figure 2, in the case of water to which nothing was added, the PH value decreased rapidly by adding 1N hydrochloric acid in 0.05ml increments. And the PH of the water to which tobermorite has been added is
As the amount of hydrochloric acid added was gradually increased, the alkalinity value remained stable. On the other hand, the pH of the water to which zeolite was added showed an acidic value before the addition of 0.1 ml of hydrochloric acid, and gradually decreased to below PH 6 after the addition of 0.2 ml of hydrochloric acid. <Effects of the Invention> As detailed above, in the porous purification material for fish and shellfish inhabited water areas according to the present invention, tobermorite, the main component thereof, exerts a PH buffering effect and removes organic matter such as fish and shellfish excrement. In addition to suppressing the pH drop caused by water, it also adsorbs some of the pollutants on its porous surface, resulting in an excellent water purification effect. Further, phosphoric acid in water reacts with calcium ions supplied from the surface of the porous purifying material of the present invention, and is appropriately crystallized and removed. Furthermore, when the porous purifying material is left in water, microorganisms inhabit its pores and oxidize the ammonia produced in the water, converting it into nitrous acid, which is said to be almost non-toxic to seafood. It nitrates to nitric acid. In addition, these microorganisms decompose organic matter that is a source of water contamination and convert it into water and carbon dioxide, making it possible to maintain an aquatic environment in which fish and shellfish can live. Therefore, according to the present invention, it is sufficient to simply spray the porous purifying material into the water where fish live.
This has the effect of making it possible to purify the water environment with simpler work compared to conventional techniques.

[Brief explanation of drawings]

Figure 1 is a diagram comparing the changes in PH after adding tobermorite and zeolite to oxidized water.
Figure 2 shows the pH when tobermorite and zeolite were added to water with a pH of 7, and then hydrochloric acid was gradually added.
It is a diagram comparing changes in .

Claims (1)

[Scope of Claims] 1. A foaming agent is added to an aqueous slurry mainly composed of silicic raw materials and calcareous raw materials, and the resulting cured product is foamed and hardened. A porous purification material for fish and shellfish habitat waters that has tobermorite as its main component and has a vacancy rate of 50 to 90%. 2. The porous purification material for fish and shellfish habitat water areas according to claim 1, wherein the tobermorite has been subjected to a neutralization treatment. 3. Claim 2, wherein the neutralization treatment is carbonation treatment.
A porous purification material for the water areas where fish and shellfish live.