JP2001181117A - Bottom sediment-improving agent and method for improving bottom sediment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottom sediment-improving agent capable of improving habitat environment of algae, living things, etc., by improving the bottom sediment of closed sea bottom, moat bottom, etc., to decrease anaerobic bacteria and provide a method for improving the bottom sediment by using the above agent. SOLUTION: This bottom sediment-improving agent is obtained by forming magnesium hydroxide having 30-97% purity into granular, pellet-like or flake-like magnesium hydroxide having a hardness of 0.3-4.0 kg/granule and 2-9 mm particle diameter. The another objective method for improving the bottom sediment comprises spraying the bottom sediment improving agent on to organic substances-rich bottom sediment at a ratio of 100 to 1,000 g/m2 to carry out decomposing treatment of organic substances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottom sediment improving agent which can improve the habitat of algae, living organisms, etc. by improving sediment such as a closed seabed and a moat bottom to reduce anaerobic bacteria. And a method for improving sediment quality.

[0002]

2. Description of the Related Art For example, when water temperature rises to 20 ° C. or more, since the flow of water is small and organic matter is easily deposited on the bottom of a closed sea area such as a bay or at the bottom of a lake, a dam lake, a canal, a moat, etc. The organic matter deposited on the bottom is oxidized and decomposed to produce organic acids such as lactic acid, propionic acid, and acetic acid, and anaerobic bacteria grow to reduce sulfur oxides, causing toxic hydrogen sulfide to emerge. It will cause damage. As a method for preventing this, a method is known in which a lime-based alkaline substance is injected to form an alkaline film on the bottom surface, thereby reducing the activity of anaerobic bacteria and suppressing the generation of hydrogen sulfide. And has been in place for many years.

However, according to the study of the present inventors, the method of raising the pH to the alkaline side using a lime-based material is that lime (CaO) is replaced with calcium hydroxide (Ca (OH) ₂ ) in seawater. , And gypsum (Ca)
(SO ₄ 2H ₂ O) and lime carbonate (CaCO ₃ ). Gypsum dihydrate (CaSO ₄ .2H ₂ O) was found to have a negative effect that sulfuric acid was separated as a nutrient source due to its high solubility, and anaerobic bacteria began to work actively.
In addition, it was also found that most of the lime became carbonated lime (CaCO ₃ ), covering the surface of the sediment, and oxygen was cut off, and no organisms, algae, and grasses were bred below it.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and efficiently improves sediment such as a closed seabed and a moat floor to prevent the growth of anaerobic bacteria and to prevent the growth of algae. The present invention has been completed for the purpose of providing a sediment improving agent and a method for improving a sediment capable of improving a habitat of a living thing or the like.

[0005]

SUMMARY OF THE INVENTION To solve the above-mentioned problems, the present invention provides magnesium hydroxide having a purity of 30 to 97%, a hardness of 0.3 to 4.0 kg / grain and a particle size of 2 kg. ~
9 mm granular or pellet-like or flake-like bottom sediment improver, and this sediment improver is added to an organic matter-rich sediment by 100-1000.
This is a method for improving bottom quality, characterized in that organic substances are decomposed by spraying at a rate of g / m ² .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the present invention, the selection of materials with a focus on improving the human living environment satisfactorily, as a result of research on the premise that they are not substances that induce natural destruction or environmental destruction,
The problem was solved by using magnesium hydroxide. Magnesium hydroxide is an alkaline agent obtained by collecting magnesium, which is one of the minerals contained in seawater, in the form of Mg (OH) ₂ . Since Mg (OH) ₂ is a substance that hardly dissolves in seawater and reacts and dissolves with an acidic substance, it has the advantage that there is no loss in application rate. Since it is decomposed into magnesium (MgSO ₄ ) and water, there is an advantage that no residue is left on the sea floor. Furthermore, in the long term, Mg (O
H) ₂ gradually dissolves, and there is also an advantage that the dissolved alkali keeps the vicinity alkaline. As a result,
If applied to places such as seabed mud, the mud will be kept alkaline and the sediment will be improved to effectively prevent the growth of anaerobic bacteria.

In the present invention, the magnesium hydroxide has a hardness of 0.3 to 4.0 kg / particle and a particle size of 2 to 9 kg.
Use as granules or pellets of mm or flakes. This is because the true specific gravity of magnesium hydroxide is as large as 2.39, while the surface layer of the sediment is soft, and the large and hard particles have the physical property of sneaking into the mud naturally before the reaction, The hardness and shape are specified based on the chemical basis that the finer the particles are, the more they disperse and settle.

[0008] Further, shell fossils can be mixed with magnesium hydroxide at a ratio of 20% or more by volume. In this case, besides mixing in advance, each bag of magnesium hydroxide and shell fossil contained in separate bags at the construction site can be used at a fixed ratio. Shell fossils are natural products produced by prehistoric crustal deformation, have long been officially recognized as feed additives, and have high safety especially when used in feed for aquaculture. This shell fossil is Ca
It is a neutral compound mainly composed of CO ₃ and has no function of eluting and keeping the surrounding area alkaline, but exerts the effect of reducing nitrogen and phosphorus generated in the decomposition process of organic substances and suppressing eutrophication. And indirectly prevent the growth of anaerobic bacteria. By using magnesium hydroxide and shell fossils at the same time, synergistic effect of promoting the reaction with acid, which is the performance of magnesium hydroxide, and increasing the sustainability of magnesium hydroxide by the porous shape which is the characteristic of shell fossils Are more preferably used in combination.

Although the above sediment improving agent can be sprayed directly on the water surface, it may be difficult to spray it due to wind, waves, or on-site conditions. It is preferable to pack 5 to 20 kg / bag in a resin bag because excellent handling properties and uniform spraying are possible.

Such a sediment improver is used in an amount of 100 to 1000 g / m ² , preferably 250 to 5
The organic matter is decomposed by spraying from the surface of the water at a rate of 00 g / m ² . Since the sediment improver is in the form of granules, pellets, or flakes having a particle size of 2 to 9 mm, it spreads over a wide area and sediments, completely covering the intended sediment layer. In addition, since the organic matter starts oxidative decomposition when the water temperature becomes 20 ° C. or more, it is preferable to spray the bottom quality improving agent immediately before the spraying.

The sediment improving agent is composed of magnesium hydroxide having a true specific gravity of 2.39 and a hardness of 0.3 to 4.
Since it is in the form of granules or pellets having a particle size of 2 to 9 mm at 0 kg / particle, or in the form of flakes, it spreads quickly from the surface of the water and sediments quickly and is 1 to 1 from the surface of the sediment.
It will remain at a depth of 0 cm. This is because the sediment surface layer is covered with soft mud by depositing organic matter converted into sludge, and the shape and the like are selected so that the sediment improver just stays in the place where the reforming is most needed. Because.

[0012]

[Examples] (Examples 1 and 2) Hardness was improved to improve the sediment quality of aquaculture fishing grounds in the shipyard in the Gravel Pond, which is a land with high red tide frequency, in Gogasho Bay, Minamisei-cho, Dokai-gun, Mie Prefecture. A sediment improver consisting of granular magnesium hydroxide having a particle size of 3 to 7 mm at 0.5 kg / particle was sprayed at a rate of 200 to 400 g / g.
Spraying was performed at a rate of m ² , and about 2 months and 3 months after the construction, the oxygen content, PH value, sulfide content, etc. of the sediment layer in the sea area were investigated (Example 1). In addition, a bottom quality improver in which magnesium hydroxide and shell fossils are mixed by 50% by volume ratio,
In the same manner, the case of spraying was examined as Example 2. The measurement results of various data are as shown in Table 1, and it was recognized that the sediment improving agent was mixed in the mud collected from the sediment layer in various places. No algae or inhabitants were found, but it was confirmed that they were all breeding after construction, and that the environment was improved. On the other hand, the mud in the sediment layer in the sea area where the sediment improver was not sprayed (Comparative Example 1) had a strong smell of sulfide, and was free of organisms and algae. The above experiments were performed by the applicant in cooperation with the Mie Prefecture Fisheries Cooperative Association.

[0013]

[Table 1]

(Examples 3 to 6) Water pumping in a ship-excavation area in a gravel basin, which is a frequent occurrence of red tide, in Gogasho Bay, Minase-cho, Dokai-gun, Mie Prefecture (Examples 3 and 4) and in Sakakibara area In the valleys (Examples 5 and 6), for the purpose of improving the bottom quality of aquaculture and fishing grounds, a bottom quality improving agent composed of magnesium hydroxide and a bottom quality improvement mixture of 50% by volume of magnesium hydroxide and shell fossils were mixed. The agent was sprayed in the same manner as in Examples 1 and 2, and the results of measurement of various data were as shown in Tables 2 and 3. Further, in Examples 3 to 6, it was recognized that the sediment improving agent was mixed in the mud collected from the sediment layer, and there was no inhabitation of living organisms (eg, shellfish and creatures) and algae before construction. However, after the construction, it was confirmed that the breeding was in all cases, and it was confirmed that the environment was improved. On the other hand, the mud in the sediment layer in the sea area where the sediment improver was not sprayed (Comparative Examples 2 and 3) had a strong smell of sulfide, and was free of organisms and algae. The above experiments were performed by the applicant in cooperation with the Mie Prefecture Fisheries Cooperative Association.

[0015]

[Table 2]

[0016]

[Table 3]

(Example 7) In the Wagoura area of Shima-cho, Shima-gun, Mie Prefecture, a sediment improver composed of magnesium hydroxide was sprayed in an amount of about 25 for the purpose of improving the sediment quality of a pearl culture fishing ground.
0 g / m ² at about 3 months, 6 months, and 9 months after construction,
Values, sulfide content, etc. were investigated. The measurement results of the various data were as shown in Table 4. On the other hand, the mud in the sediment layer in the sea area where the sediment improver was not sprayed (Comparative Example 4) had a strong smell of sulfide, and was free from living things and algae. The above experiments were performed by the applicant in cooperation with the Fisheries Agriculture and Forestry Division, Shima Town, Mie Prefecture.

[0018]

[Table 4]

[0019]

As is apparent from the above description, the present invention efficiently improves sediment such as a closed seabed and a moat floor, prevents the growth of anaerobic bacteria, and reduces the habitat of algae and living organisms. It can be improved. Therefore, the present invention greatly contributes to industrial development as a sediment improving agent and a sediment improving method that have eliminated the conventional problems.

Claims (5)

[Claims] 1. Magnesium hydroxide having a purity of 30 to 97%, in the form of granules or pellets having a hardness of 0.3 to 4.0 kg / particle and a particle size of 2 to 9 mm, or flakes. A bottom quality improving agent, characterized in that: 2. A bottom sediment improving agent comprising the fossil shell fossil mixed with the magnesium hydroxide according to claim 1 at a volume ratio of 20% or more. 3. A bottom sediment improving agent characterized in that the sediment improving agent according to claim 1 or 2 is packed in a bag made of a biodegradable resin. 4. The method according to claim 1, wherein the sediment improving agent according to any one of claims 1 to 3 is applied to the sediment rich in organic matter at a rate of 100 to 1000 g / m ² to decompose the organic matter. Characteristic method of improving bottom quality. 5. A sediment improving agent is added from 1 to 10 from the surface of sediment.
5. The method for improving bottom sediment according to claim 4, wherein the method is adapted to remain at a depth of cm.