JP2917096B2 - Water quality and bottom sedimentary malignant improver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improving agent for improving the water quality and sediment of a closed water area which is deteriorated by spraying the same.

[0002]

2. Description of the Related Art In recent years, closed water bodies, such as inland seas, inner bays, lakes and marshes, which have a large source of pollution in the hinterland, are eutrophic due to a large inflow of pollutant loads and easy accumulation of pollutants. And sediment pollution is increasing. To cope with this, the Water Pollution Control Law, the Seto Inland Sea Environmental Conservation Special Measures Law, the Lake Conservation Water Quality Conservation Law, and the regulation of nitrogen and phosphorus drainage related to lakes have been enacted.

[0003] In a closed sea area typified by the Seto Inland Sea, the inflowing phosphorus and nitrogen are stagnant, and red tides are generated, thereby causing fishery damage, which greatly affects the fishing environment. In addition, freshwater red tides and blue-green algae occur abnormally in lakes and marshes that are sources of drinking water, which causes problems in filtration of water supply facilities and unpleasant odors.

[0004] Further, in a farm, toxic hydrogen sulfide is generated from the bottom sediment due to the occurrence of red tide and anoxic water mass, and as a result, it has been reported that a large amount of cultured fish is killed by death. Therefore, it is urgently necessary to prevent the generation of hydrogen sulfide in aquaculture farms in order to prevent the mass death of cultured fish.

To solve these problems, concrete methods such as tillage, aeration, spraying of chemicals (lime and clay), sand covering, and dredging have been implemented as improved techniques.

[0006] Cultivation is a method of forcibly stirring, inverting, and diffusing a surface layer of sediment by towing a cultivator to physically contact undecomposed organic substances in anoxic or anoxic state with oxygen. Aeration is a method of forcibly sending air to the sea floor to increase the dissolved oxygen concentration. Lime spraying is a method of spraying quick lime, maintaining the pH on the alkaline side, and fixing and removing pollutants as hardly soluble compounds. Clay spraying is a method of spraying clay minerals (montmorillonite-based clay, whose main components are SiO ₂ and Al ₂ O ₃ ), coagulating and sedimenting an organic suspension in water, and coating the sediment. Sand covering is a method of completely covering the sediment with sand to block the polluted sediment surface from the aqueous phase. Dredging is a method of collecting polluted sediment itself and discarding it elsewhere.

[0007] The application of the above-mentioned improved technologies includes problems (diffusion of pollutants, pollution of water bodies, temporary suspension of production, treatment of secondary sludge) and costs of implementation. It is necessary to select an improved technology.

[0008] The chemical spraying method for spraying clay or lime has the advantage that the cost of implementation is extremely low compared to other improved techniques, the surrounding water area is less contaminated during work, and can be easily implemented.

[0009] However, in the lime spraying method which is the least expensive in the conventional drug spraying method, Japanese Unexamined Patent Publication No. 2-218488 points out the following points regarding the quick lime to be administered. 1) Quicklime generates heat when exposed to water, and may cause fire or burns. 2) Since quicklime is disintegrated and powdered when touched with water, the water in the spray area may become cloudy and cause adverse effects such as water pollution. 3) Since quicklime is relatively soft and easily pulverized with a mechanical impact file or lip, it is easy to cause smoking when spraying over a wide area in the air and harmful to nearby areas. Therefore, in recent years, a method of spraying slaked lime which is easy to handle instead of quick lime has been proposed.

[0010]

The problem of the present invention is that lime applied to lime hydrates from oxides to hydroxides. In Iwashita and Shimomoto, Gypsum and Lime, Vol. 234, (1991), p. 102, lines 33-38, states, “The main component of lime rapidly changes to calcium hydroxide on the seabed. Magnesium ions are found in seawater. 1300pp
Since about m is contained, calcium ions replace magnesium ions, and magnesium hydroxide is generated. "

The magnesium hydroxide produced here is nascent magnesium hydroxide, which is a submicron colloidal ultrafine particle. For this reason, in water, it is easily diffused by convection and causes clouding (smoking). In Seki, lime, Vol. 337, (1984), p. 34, line 17-p. 1, line 1, `` Even if quicklime is in seawater, it becomes slaked lime, so spraying slaked lime will be the same, Slaked lime makes the seawater turbid, which is undesirable, but if the particles are suspended in the seawater, it will have a great effect on others. "
He pointed out the effect of fine particles. Therefore, it is necessary that the improving agent does not cause such smoking.

Regarding the toxicity of hydrogen sulfide Iwashita et al., In gypsum and lime, vol. 234, (1991), p. 102, lines 10-15, states that "hydrogen sulfide dissolved in water is in an undissociated state (H ₂ It has acute toxicity to fish and shellfish due to its presence in S. For example, its half-lethal concentrations in trout, invertebrates and cats are 0.0087 ppm, 0.20 ppm and 25 μg / kg, respectively, Very large. "

The mechanism of hydrogen sulfide generation in the sediment has been described as the relationship between sulfate reducing bacteria and hydrogen sulfide due to the pH of the generated environmental water. Saito, in lime, Vol. 359, (1985), p. 17, lines 5-11,
"When the organic matter deposited on the sea floor decomposes and decomposes, it consumes oxygen and the bottom becomes anoxic and the anaerobic sulphate-reducing bacteria begin to work. This activity is active on the surface of the organic matter, Reduces sulfates and emits hydrogen sulfide.
Hydrogen sulfide generated from the bottom mud is mostly due to the action of this fungus. However, this fungus also has its weaknesses. It does not multiply unless the seawater is acidified to some extent. Conversely, it does not proliferate under weak alkaline conditions and cannot survive at pH 8.5 or higher. For this reason, the lime sprayed on the sea floor is
Is kept alkaline to inhibit the growth of sulfate-reducing bacteria for a long period of time, thereby preventing mass production of hydrogen sulfide. "

In Seki, lime, Vol. 337, (1984), p. 33, lines 7-9, "In addition, the range of pH of the environment suitable for growth for each bacterium is determined. In Case of
6.5 to 7.5, ie neutral, cannot survive at an alkalinity of 8.5 or higher. Since seawater has a weak alkaline pH of 8.2 to 8.3, reduction of sulfate does not occur under normal conditions. In the end, organic acid production due to organic decay, pH
As long as conditions such as reduction of oxygen and oxygen-free condition are prepared, hydrogen sulfide is generated as much as possible. In order to prevent this, it is necessary to reduce the amount of organic substances, supply oxygen, or increase the pH. " Therefore, in order to prevent the generation of hydrogen sulfide, it is necessary to maintain the pH at a slightly alkaline level for a long period of time.

Growth factors of algae in closed freshwater areas Iwashita: Gypsum and lime, 234, (1991), p. 107, p. 26-108.
In line 6, "Eutrophication in enclosed waters and the resulting growth of algae require light, moderate water temperature, nitrogen, phosphorus, minerals, etc. If any of these elements are missing This suggests that the growth of algae is suppressed. In other words, it suggests that abnormal growth of algae is suppressed by lowering the phosphorus concentration. " Iwashita also uses plaster and lime, Volume 234, (1991), p. 108, 2
In lines 4 to 4, the results of experiments on the algae suppression effect using substances including magnesium hydroxide were reported as "all the examined substances except for calcium carbonate were effective in suppressing the algae." I have. Therefore, there is a need for an improver that reacts with phosphorus to form a poorly soluble compound. Magnesium-based hardly soluble compounds include magnesium phosphate and magnesium ammonium phosphate.

Matsumura further states that gypsum and lime in purifying freshwater areas, Vol. 229, (1990), pp. 111, lines 15-25, states that "ammoniacal nitrogen eluted by decomposition of organic matter in sediment is dissolved oxygen. When dissolved oxygen in water is consumed, it dissolves in the form of ammonia nitrogen, which is mostly dissolved as ammonium ions or ammonia gas toxic to fish, and NH ₄ ⁺ →
The reaction of NH ₃ ↑ + H ⁺ equilibrates between pH 7 and 12, and shifts to the right side as the pH increases. " Therefore, in order to reduce the concentration of dissolved ammonia gas, which is toxic to fish, in fresh water, it is necessary to keep the alkali gas weakly and to diffuse it.

Nittatani et al., On water alteration and aquaculture pH in freshwater fish farming, Lime, Vol. 419, (1990), p. 5,
In line 6-12, `` When the water change phenomenon occurs, the pH value of the daytime is usually 9.0-9.6, but the pH is 7.5-7.9 even if it is mild.
In addition, when accompanied by mortality, the pH drops to 7.1 to 7.4. " Therefore, it is necessary to maintain the pH of water quality to be slightly alkaline even in the culture of freshwater fish.

Next, since carbonate ions are present in water in the range of 50 ppm to 90 ppm, slaked lime undergoes carbonation to become calcium carbonate. Iwashita, Shimomoto: Plaster and Lime, Volume 234, (199
1), p. 109, lines 8-10, reports that "lime sprayed in water gradually reacts with carbon dioxide to change into calcium carbonate and is completed in one to two months."
In addition, Shimomoto said in lime, vol. 417, (1990), p. 21, lines 17-20, that `` in any case, quicklime that had been sprayed in the ocean was replaced by magnesium ions in seawater, In fact, some of the lime sprayed reacts with CO2 in seawater to form calcium carbonate (aragonite). "

Regarding the reactivity of lime, Japanese Patent Application Laid-Open No. 4-200788
Then, "The reactivity of calcium ions and carbonate ions is
Greater than the reactivity of calcium and phosphate ions. ''
It has been shown that the reactivity of carbonation in water is extremely high. Therefore, the lime-based improver has a drawback of producing calcium carbonate as a by-product because the reaction with carbonate ions proceeds. As a result,
Since the surface of the hydroxide is coated with the carbonate, the pH maintaining effect and the reactivity for forming the hardly soluble compound are lost.

Since slaked lime has a high solubility in magnesia, the indicated pH when poured into water has a high characteristic. Therefore, when the improving agent is administered in water, the pH maintaining effect expected from the improving agent is also important, but it is necessary to consider the fluctuation of the pH of environmental water which increases due to the administration. In particular, in a freshwater system having a small pH buffering capacity, it is necessary to administer carefully.
Takashima et al. Have advanced technologies for purification and water treatment of environmental water,
(1994), p. 61, lines 21-22 point out that "it is necessary to pay attention to the pH and reconsider the amount of lime added". Generally, when hydroxide is administered to the body of water,
Care must be taken because excessive administration will increase the effect of pH.

The lime spraying method is the most inexpensive and effective method for improving the water quality and the sediment environment. The effect is achieved by keeping the water quality as well as the sediment environment slightly alkaline. However, the lime-based improver is a strong alkali and generates heat by reaction with water.
Maintenance effect, inability to sustain the formation reaction of poorly soluble compounds,
Further, there are problems such as a large number of pH fluctuation factors in the water area. Therefore, in order to improve water quality and sediment quality, an inexpensive improver which is safe for the environment and workers and maintains weak alkalinity for a long period of time is required.

The present inventors have conducted intensive studies and, as a result, have solved the above-mentioned problems, and at the same time, have come up with an inexpensive and effective water quality and bottom sedimentary system improving agent which can be provided to the chemical spraying method.

[0023]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to find a range of composition and material properties for water quality and sedimentary mica based improvers.

The above-mentioned object is achieved only by the gypsum-based granules described in the claims of the present invention. That is,
Magnesium hydroxide, magnesium oxide, magnesite, dolomite, etc., composed of one or more materials of formic-based powders, with a MgO equivalent content of 30% or more,
And the water content is 20% or less, self-disintegrating after being put into water, the particle size of the mafic-based powder is 5 μm to 100 μm, and the specific gravity is 2.2 g / cm ³ or less. Is preferably in the entire range of 0.01% to 5%. The powder in the above range easily disintegrates in water,
The pH can be kept on the alkaline side for a long time. The mafic powder is limited to those limited in the above range.

[0025] When the content of magnesium-based MgO is 30% or less, the effect of maintaining pH in water and sediment is not efficiently achieved, and it is necessary to increase the amount of the modifier to be added. Therefore, the MgO-equivalent content of the mafic component is preferably 30% or more, and more preferably 30% to 70%. 20% moisture
In the case described above, it is difficult to form a granular material, which is not preferable.
Therefore, the water content is preferably 20% or less. Further, since it is an improving agent based on a mafic system, it has a characteristic that the effect of the carbonation reaction seen in a lime system does not disappear due to the progress of the carbonation reaction.

The improver of the present invention exhibits weak alkalinity by disintegrating, dispersing and dissolving after being introduced into water, and the effect can be obtained by maintaining this effect over a long period of time. This effect depends on the specific gravity, particle size, and specific surface area of the granular material.

The disintegration of the improver depends on the specific gravity. The granules charged in water are mainly
Water enters the pores and collapse begins. The degree of the distribution of the pores can be indirectly inferred by measuring the specific gravity of the granular material. When the specific gravity of the granules is 2.3 g / cm ³ or more, the disintegration and dispersibility in water are reduced to form high-strength granules, and at the same time, the cost is increased and it is not economical. Therefore, the specific gravity must be 2.
Preferably 2 g / cm ³ or less, further a range of 1.0g / cm ³ ~1.9g / cm ³ are preferred.

[0028] The dispersibility of the improver depends on the particle size. When the particle size is 5 μm or less, the particles are easily diffused by a water flow, and smoking is likely to occur. Also 10
If it is 0 μm or more, the dispersion range after collapse becomes narrow and the reactivity decreases, so that it is necessary to increase the input amount, which is not preferable. Therefore, the particle size is preferably in the range of 5 μm to 100 μm.

[0029] The solubility of the improver depends on the specific surface area. When the specific surface area is 5 m ² / g or less, the indicated pH is lowered because the solubility is lowered, which is not preferable. Therefore, the specific surface area is preferably 5 m ² / g or more, and more preferably 5 m ² / g to 50 m ²
/ g is preferred.

The presence of the soluble magnesium salt has a binder effect when forming the powder. In addition, since the soluble magnesium salt has a high solubility, when it is put into water, it promotes the disintegration of the granular material. The soluble magnesium salt in this case is not limited as long as it is any soluble magnesium compound represented by magnesium chloride, magnesium sulfate, magnesium nitrate and the like.

When the effect of the formability of the powder is expected, the content of the soluble magnesium salt is preferably 0.01% or more. Further, when the amount is 5% or more, the soluble magnesium salt is dried and hardened on the surface of the granular material, so that the disintegration in water is reduced. Therefore, the preferable range of the content of the soluble magnesium salt is 0.01% to 5%.

By setting the above range, it is easy to handle as an improving agent, and there is little pH fluctuation with respect to environmental water.
It is possible to provide an inexpensive improver having a pH maintaining effect over a long period of time. The measured values of the particle diameter, specific surface area, and pore volume described in the text are each measured by the following methods. Particle size: Measured according to JSF-T-131, Japan Society of Civil Engineers. Specific surface area: BET specific surface area measured by nitrogen adsorption method. Pore volume: Measured by mercury porosimeter by mercury intrusion method.

[0033]

【Example】

Examples 1 to 5 Using magnesium hydroxide and magnesium oxide shown in Table 1, five kinds of almond-like (20 × 40 mm) granules having different specific gravities were prepared by a briquette machine, 10 pieces each. this
The pieces were uniformly arranged on a 2000-μm sieve, and allowed to stand in a 10-liter container. Water was poured until the granules sank so that the granules were not directly exposed to water. After standing for 24 hours, the state of the collapsed granules and the state of the supernatant (smoking) were observed. Table 2 shows the results. The granules began to disintegrate when water was injected, releasing air from inside the granules. At the beginning of the collapse, the supernatant becomes slightly cloudy,
The clarity of the liquid surface was maintained by sedimentation and dissolution of the fine particles.

[0034]

[Table 1]

[0035]

[Table 2]

Example 6 A sludge from a prawn farm was spread in an aquarium (450.times.250.times.250) to a thickness of 50 mm, and twelve shrimp prawns were placed in the tank to observe seawater. Example 2 was used as a magnesia improving agent, and was administered at a rate of 400 g / m ² with respect to the area of the aquarium. In addition, once every three days, 10% of the total amount of seawater was replaced, and the pH change and the growth process of prawn were observed. Table 3 shows the results of the pH change. The masonry improver shows pH 8.45 even after 90 days from the addition,
It was confirmed that there was no carbonation reaction and there was a pH maintaining effect over a long period of time. The prawns placed in the aquarium grew repeatedly after molting, and it was confirmed that the mica-based modifier had no fish toxicity.

Example 7 Into a 3 liter beaker filled with tap water, 20 mm of sludge collected from a domestic drainage ditch where blue-green algae was generated was spread, and the improving agent of Example 2 was added at a rate of 100 g / m ² to obtain a blue-green algae. The occurrence was observed. In the beaker containing the mafic modifier, no bloom was observed, and diatom growth was observed. After 16 days, the change in the visibility using a fluorometer was as follows: the visibility of 50 cm immediately after the addition of the improving agent was reduced to 48 cm.

[0038]

[Table 3]

Comparative Examples 1-2 In the same water tank containing prawns as in Example 6, a water tank containing no lime-based improver and no improver was prepared instead of the mafic-based improver, and the pH change and The growth process was observed. Once every three days, 10% of the total seawater was replaced.
Table 4 shows the results of the pH change. On the 30th day after the addition, the lime system of Comparative Example 1 dropped to near the pH of the non-added seawater. X-ray diffraction analysis of the mineral composition of the lime-based modifier on the 30th day passed confirmed the progress of the carbonation reaction with a mixture of calcium carbonate (calcite, araconite), calcium hydroxide, and magnesium hydroxide. Was. The prawns put in the aquarium grew repeatedly after molting.

[0040]

[Table 4]

COMPARATIVE EXAMPLE 3 In a 3 l beaker filled with tap water, 20 mm of sludge collected from a domestic drainage ditch where blue water was generated was spread, and the generation status of blue water was observed without adding an improving agent. Observation start 3
A blue-green algae occurred in the beaker from the day. After 16 days, the change in the transparency with the fluorometer is from 50 cm at the start to 25 cm
Down to

Reference Example The sedimentation velocity of the dispersed particles collapsed in Example 2 was 1.8 m / h. Next, quicklime was added to seawater to produce new magnesium. When this new magnesium was fractionated and added to the water tank at the ratio of Example 2, the inside of the tank became cloudy. The sedimentation velocity of this new magnesium measured in the sedimentation tube is 8 × 10 ^-4 m / h
Met. From the above results, it can be seen that lime-based newly formed magnesium causes a problem of smoking and is not suitable as a modifier.

[0043]

As described above, by administering the improving agent of the present invention to deteriorated water quality and sediment, the self-disintegration, dispersion and dissolution of the improving agent are maintained for a long time, and the water quality and sediment are reduced. It can be maintained weakly alkaline. The following effects can be obtained by maintaining a weak alkalinity. 1) The growth of sulfate-reducing bacteria, which is a source of hydrogen sulfide in sediment, can be suppressed, and death due to hydrogen sulfide can be prevented. 2) Ammonium-on produced by the decomposition of organic matter by decay can be equilibrium-transferred to ammonia gas, which facilitates diffusion into the atmosphere by aeration. 3) It can control mortality due to acidification of aquaculture water quality. 4) In addition, the formation of poorly soluble compounds with phosphorus in water quality can reduce the phosphorus concentration and prevent abnormal growth of blue-green algae.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change over time in pH transition in Example 6, Comparative Example 1 and Comparative Example 2 of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-247508 (JP, A) JP-A-49-66564 (JP, A) JP-A-63-190708 (JP, A) 26967 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 1/66 521 C02F 1/00

Claims (2)

(57) [Claims] The present invention is characterized in that it is composed of one or more materials of the formic acid-based granules, has a MgO-equivalent content of 30% or more, a water content of 20% or less, and a soluble magnesium salt of 0.01% or less.
A water quality and sediment improving agent containing 5% and self-disintegrating after being put into water. 2. The particle size of the magnesia-based powder is 5 μm to 100 μm,
2. The water and sediment improving agent according to claim 1, wherein the specific gravity of the granular material is 2.2 g / cm ³ or less.