JP2004290893A - Method and apparatus for improving/purifying bottom mud - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for improving/purifying bottom mud which can surely improve a bottom mud layer and at the same time improve the water quality of a bottom layer by supplying oxygen efficiently to the bottom mud layer to remarkably increase dissolved oxygen without destroying water temperature stratification. <P>SOLUTION: A layer 100 of hyperfine bubbles comprising gas containing at least oxygen is formed so as to cover the surface of the bottom mud 90 accumulating on the water bottom at a prescribed depth. Oxygen is supplied from the layer 100 of the hyperfine bubbles to improve and purify the bottom mud 90. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for improving and purifying a bottom mud layer, for example, for improving and purifying a bottom mud layer deposited in a closed water area such as a dam reservoir using microbubbles.
[0002]
[Prior art]
In closed water areas such as dam reservoirs, inner bays, rivers, reservoirs, brackish lakes, etc., various types of water quality disturbances occur due to sedimentation of sediment and the resulting deoxygenation of the bottom layer. In order to prevent this water quality obstacle, methods such as bottom mud dredging and sediment covering with gravel are generally adopted, but such a method completely prevents water quality damage due to the influence of bottom mud. There was a problem that it was not possible to do so and the cost was high.
[0003]
In order to solve such a problem, for example, surface water in a water area such as a lake, or water prepared in advance, using a pipe laid around the bottom of the water area, directly above the bottom mud deposited on the bottom of the water area or A method of increasing the dissolved oxygen in the water directly above the bottom by injecting it into the bottom mud, thereby insolubilizing the nutrients contained in the bottom mud and preventing nutrients from being supplied to the water. (For example, see Patent Document 1).
[0004]
Also, for example, a microbubble generator is arranged on bottom mud (sludge), and an airflow is generated by generating microbubbles from the microbubble generator toward the water surface, and a circulating flow is formed by the airflow. There is a method of supplying oxygen to bottom mud by exchanging surface water and bottom water (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-8-281292 (FIG. 1, columns 2 to 3)
[Patent Document 2]
Japanese Patent No. 3026023 (FIG. 1, [0008] [0009])
[Patent Document 3]
JP-A-2002-102894 ([0008] to [0020])
[0006]
[Problems to be solved by the invention]
However, in the former method, although the dissolved oxygen can be increased in a relatively narrow range, the dissolved oxygen is increased just above or in the mud layer. There is a problem that the amount of sediment cannot be sufficiently improved.
[0007]
In the latter method, the amount of dissolved oxygen in water is relatively large because fine bubbles are used.However, oxygen is supplied to the sediment by circulating water, so that it is supplied to the sediment itself. The amount of oxygen to be produced is relatively small, and there is a problem that the bottom mud cannot be sufficiently improved.
[0008]
Furthermore, by mixing the polluted water with active air accompanied by a large amount of electromagnetic fields, and spraying the polluted water mixed with fine bubbles to create a stream of water throughout the water area, the action of the electromagnetic field is used to create a bottom mud layer. There is a method of improving the dissolved oxygen ratio of the sapphire (see, for example, Patent Document 3). However, in this method, a water flow is created in the entire water area, and oxygen contained in the circulated water is caused to enter the bottom mud layer by the action of an electromagnetic field. Therefore, since the updraft is generated by mixing the entire pond, it can be applied to a relatively narrow water area.For example, the effect area is limited in a relatively wide water area such as a dam reservoir, and the electromagnetic field is limited. It requires a large-scale facility for utilizing the function of (1) and is not practical.
[0009]
Generally, at a dam, a water temperature stratification is formed within a range of several meters from the surface of the water, causing problems such as burning, and the problem of low oxygen and anoxia in the lower part. A thermocline with a difference is formed. In such a dam, turbid water flowing in the event of heavy rain flows into the thermocline, and when the amount of water increases, the outlet is formed at the depth where the thermocline is formed. It is designed so that stratified and lower layer water does not mix. Therefore, even if it is for improving water quality, if the whole is agitated, other environmental problems will occur.
[0010]
In view of such circumstances, the present invention significantly improves dissolved oxygen by efficiently supplying oxygen to the bottom mud layer without destroying water temperature stratification, and can reliably improve the bottom mud layer and improve the water quality of the bottom layer. An object of the present invention is to provide a method and apparatus for improving and purifying bottom mud that can be improved.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, a layer of ultrafine bubbles made of a gas containing at least oxygen is formed so as to cover a surface layer of sediment deposited on a water bottom at a predetermined depth, and the layer of the ultrafine bubbles is formed from the layer of ultrafine bubbles. The present invention is directed to a method for improving and purifying bottom mud by supplying oxygen to the mud to improve and purify the bottom mud.
[0012]
In the first aspect, since the layer of ultrafine bubbles formed so as to cover the surface layer of the bottom mud stays for a relatively long time, oxygen is effectively applied to the bottom mud from the layer of ultrafine bubbles. Supplied to As a result, the quality of the bottom mud is improved, and eutrophication due to elution of nutrients and metal salts from the bottom mud due to anaerobic conditions is prevented, and the quality of bottom water is remarkably improved.
[0013]
According to a second aspect of the present invention, in the first aspect, the gas is an oxygen gas having a concentration of 95% or more, wherein the gas is an oxygen gas having a concentration of 95% or more.
[0014]
In the second aspect, since the oxygen concentration of the ultrafine bubbles is high, the dissolved oxygen in the bottom mud is significantly improved.
[0015]
A third aspect of the present invention is the method for improving and purifying sediment of the first or second aspect, wherein the gas is cooled to a temperature of about the water temperature at the predetermined depth.
[0016]
In the third aspect, since the ultrafine bubble layer is cooled to the same level as the water temperature at a predetermined depth, the density flow phenomenon can be effectively used, and the ultrafine bubble layer can be relatively easily formed over a wide area. Is done.
[0017]
According to a fourth aspect of the present invention, there is provided a method for improving and purifying bottom mud according to any one of the first to third aspects, wherein the method improves and purifies sediment deposited on a water bottom in a closed natural water body.
[0018]
In the fourth aspect, the water quality of the closed natural water area is improved together with the improvement of the bottom mud.
[0019]
According to a fifth aspect of the present invention, there is provided an oxygen gas generator for generating an oxygen gas having a predetermined concentration, and an oxygen gas disposed at a predetermined depth near a surface layer of sediment deposited on a water bottom and supplied from the oxygen gas generator. And an aerator unit having a plurality of aerators for horizontally injecting as fine bubbles in the horizontal direction.
[0020]
In the fifth aspect, by injecting the ultrafine bubbles in the horizontal direction, a layer of the ultrafine bubbles is formed so as to cover the surface layer of the bottom mud, and oxygen is supplied to the bottom mud from the layer of the ultrafine bubbles. The bottom mud is improved and purified.
[0021]
According to a sixth aspect of the present invention, there is provided the method for improving and purifying bottom mud according to the fifth aspect, wherein the oxygen concentration of the oxygen gas is 95% or more.
[0022]
In the sixth aspect, oxygen effectively penetrates into the bottom mud, and the bottom mud is greatly improved and purified.
[0023]
A seventh aspect of the present invention, in the fifth or sixth aspect, further comprises a cooling device for cooling the oxygen gas, wherein the ultra-fine bubbles injected from the aerator are cooled to a water temperature at the predetermined depth. An apparatus for improving and purifying sediment characterized by cooling.
[0024]
In the seventh aspect, the density flow phenomenon can be effectively used, and a layer of ultrafine bubbles can be formed over a wide range.
[0025]
An eighth aspect of the present invention is the air conditioner according to any one of the fifth to seventh aspects, wherein the aerator unit is connected to a fixed weight arranged on the bottom of the water, and levitation means for floating the aerator unit is connected. The unit is fixed at a predetermined position via the fixed weight, and is an apparatus for improving and purifying sediment.
[0026]
In the eighth aspect, the aerator unit can be stably held at a predetermined depth without being fixed to the water bottom, and is not affected by the height of the water surface.
[0027]
A ninth aspect of the present invention is the ninth aspect, wherein in the eighth aspect, the levitation means includes a connecting wire that is folded back via a pulley having one end connected to the aerator unit and fixed to a mooring member moored on the water surface. A bottom mud improving / purifying apparatus, characterized in that it is a floating weight of a predetermined weight provided on an end side and suspended in water.
[0028]
In the ninth aspect, the aerator unit is connected to the fixed weight, and is stably held while being pulled upward by the floating weight.
[0029]
According to a tenth aspect of the present invention, in the eighth aspect, the levitation means is a float member which is provided also in the aerator unit and generates buoyancy to a degree capable of levitation of the aerator unit. It is in the mud improvement and purification equipment.
[0030]
In the tenth aspect, the floating member is stably held in a state where it is connected to the fixed weight and is pulled upward by the float member while obtaining buoyancy.
[0031]
Here, anaerobic decomposition is performed by anaerobic microorganisms in bottom water and sediment that have become anaerobic and anaerobic due to the progress of eutrophication. Oxidative decomposition of CO ₂ Organic acids such as acetic acid accumulate. In addition to causing odors, hydrogen sulfide forms a blue tide when accumulated in a closed sea area, for example. In addition, since the efficiency of organic matter decomposition is much lower than that under aerobic conditions, the accumulation of organic pollutants and the accumulation of sludge on the water bottom progress.
[0032]
In addition, when the bottom mud is exposed to a low oxygen state for a long time, various substances including oxygen in the bottom water are reduced. That is, the mineral contains a large amount of carbon salts and sulfides such as iron and manganese, and is reduced to elute the ionic state of iron and manganese. The eluted iron and manganese, for example, in dam reservoirs and the like, cause water purification dysfunction in water supply and black water and red water damage in the downstream. Also, nutrients such as nitrogen and phosphorus adsorbed on the soil particles are released and eluted in water as the salts are reduced and eluted. The eluted nutrients are used as a causative substance of eutrophication for algae growth in the surface layer, and promote eutrophication of water bodies.
[0033]
In other words, from the low oxygenated bottom water to the water bottom, various substances including nutrients dissolve and float due to elution from sediment and sedimentation / sedimentation from the surface layer due to hypoxia, Electric conductivity and metal salt concentration increase, and organic sludge accumulates on the water bottom.
[0034]
In the present invention, since a layer of ultrafine bubbles is formed so as to cover the surface layer of the bottom mud deposited on the water bottom, sufficient oxygen is supplied to the anaerobic bottom mud, and the redox of the bottom mud surface is reduced. As the potential increases, the form of organic matter decomposition (energy metabolism form) by microorganisms shifts from anaerobic decomposition to aerobic decomposition. With the shift from anaerobic decomposition to aerobic decomposition, the generation of sulfide and methane gas, which are the source of offensive odor, is first suppressed, and then nutrients such as nitrogen and phosphorus in the bottom water are oxidized and insoluble metal These concentrations in the bottom water are reduced by salt formation, sedimentation and adsorption and fixation in the sediment. Furthermore, the denitrification reaction by nitrate reduction is activated, and the concentration of inorganic nitrogen ions in the bottom water decreases. When the oxygen concentration is widespread and the environment is sufficiently restored to an aerobic environment, the respiratory decomposition of organic matter by microorganisms becomes active, the decomposition of organic matter accumulated in the bottom mud progresses, and the bottom mud surface is reformed and becomes sandy At the same time, the amount of sediment decreases.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
[0036]
FIG. 1 is a schematic diagram of a bottom mud improvement / purification device according to Embodiment 1 of the present invention.
[0037]
The method for improving and purifying the bottom mud according to the present invention includes, for example, supplying dissolved oxygen by supplying micro-bubbles to the bottom mud layer deposited in a closed water area such as a reservoir to increase dissolved oxygen. It is a method of improving and purifying. As shown in FIG. 1, the bottom mud improving / purifying apparatus according to the present embodiment supplies an aerator unit 10 having a plurality of aerators 11 for generating ultra-fine bubbles, and supplies a predetermined concentration of oxygen to each aerator 11. And an oxygen generator 20 and a compressor 30.
[0038]
The aerator unit 10 is connected to a pressure water pipe 13 through which bottom water is sucked by a pressurizing pump 12 and supplied with pressurized water obtained by pressurizing the bottom water, and an air header 14 from an oxygen generator 20 through an air supply tube 25. An air supply pipe 15 for allowing the supplied oxygen to flow into each aerator 11 is provided. In the pressure water pipe 13, for example, ten to several tens, in this embodiment, twenty aerators 11 are fixed at predetermined intervals. Further, in the present embodiment, the pressure water pipe 13 functions as a frame, and the pressurizing pump 12 and the air header 14 are also fixed to the pressure water pipe 13. The pressurizing pump 12 is driven by receiving power supply from a power source 40 installed on land.
[0039]
Further, in the present embodiment, a cooling device 50 for cooling oxygen is provided between the air header 14 and the oxygen generator 20, and the oxygen supplied from the oxygen generator 20 is supplied to the aerator by the cooling device 50. The unit 10 is cooled to a temperature approximately equal to the water temperature at the depth where the unit 10 is installed. Then, the oxygen cooled by the cooling device 50 is supplied to the air header 14 via the air supply tube 25.
[0040]
The aerator 11 generates ultra-fine bubbles having a diameter of 20 μm or less, preferably 10 μm or less, and sprays water containing the ultra-fine bubbles. The pressure water sucked into the pressure water pipe 13 by driving the pressurizing pump 12 flows into each aerator, and oxygen flows from the air supply pipe 15 due to the negative pressure generated by the flow of the pressure water. However, when the installation depth of the aerator unit 10 is relatively deep, for example, when the water depth is 15 m or more, it is preferable to forcibly supply oxygen. This is because the water pressure increases as the water depth increases, and oxygen cannot be sufficiently sucked by only the negative pressure generated by the flow of the pressurized water. For example, in the present embodiment, a compressor 31 is provided on a fixing means 60 to be described later, and the compressor 31 forcibly supplies air to each aerator 11 via the air supply tube 25.
[0041]
Then, a gas-liquid two-layer swirling flow is generated by the pressurized water and oxygen flowing into the aerator 11, and the gas (oxygen) is subdivided by a strong shear force generated near the central axis of the swirling flow to include ultrafine bubbles. A gas-liquid multiphase flow is generated and injected into water. The structure of the aerator 11 is not particularly limited as long as it can generate ultrafine bubbles having a predetermined diameter.
[0042]
Further, the aerator unit 10 is suspended at a predetermined depth by a fixing means 60 such as a raft floating on the water surface and moored on the shore and arranged at a predetermined depth. Specifically, the aerator unit 10 is fixed to an elevating means 70 such as a winding device provided on the fixing means 60 so as to be able to move up and down via wires 80 and the like. The method of fixing the aerator unit 10 is not particularly limited. For example, the aerator unit 10 may be fixed to an anchor at the bottom of the water, or an anchor may be attached to the aerator unit itself and fixed to the bottom of the water.
[0043]
The oxygen generator 20 generates oxygen gas having a predetermined concentration, in this embodiment, oxygen gas having a concentration of 95% or more, and supplies the oxygen gas to the air supply pipe 15 of the aerator unit 10. Specifically, the oxygen generator 20 generates oxygen gas having a concentration of 95% or more by separating and removing nitrogen from the air supplied from the compressor 30, and supplies the oxygen gas to the air supply tube 25. The air is supplied to the aerator 11 through the air. In order to generate oxygen gas having a concentration of 95% or more, the compressor 30 supplies air to the oxygen generator 20, for example, about 10 times the required amount of oxygen gas.
[0044]
Hereinafter, a method for improving and purifying a bottom mud using such a device for improving and purifying a bottom mud will be described.
[0045]
First, the mooring raft (fixing means) 60 on which the aerator unit 10 is suspended is moored at a predetermined position, and the aerator unit 10 is lowered to a predetermined depth, that is, immediately above the bottom mud layer 90 deposited on the water bottom, and fixed. Here, the arrangement depth of the aerator unit 10 is preferably 10 m or less when arranged in seawater, and 20 m or less when arranged in freshwater. That is, the bottom mud layer improvement / purification device of the present invention can be suitably used for improvement / purification of a bottom mud layer deposited at a relatively deep place. Although this point will be described in detail later, if the arrangement depth of the aerator unit 10 is too shallow, the rate at which the ultrafine bubbles rise will increase, and oxygen cannot be supplied to the bottom mud layer. .
[0046]
With the aerator unit 10 installed at a predetermined depth in this manner, the pressurized pump 12 allows the pressurized water to flow into each aerator 11 via the pressurized water pipe 13, while the negative pressure due to the flow of the pressurized water and the compressor Oxygen is supplied by forced air supply by 31. At this time, the oxygen is cooled by the cooling device 50 to a temperature equal to the water temperature at the installation depth of the aerator unit 10 and supplied to each aerator 11. Then, a gas-liquid mixed phase flow including the ultrafine bubbles generated in each aerator 11 is injected to form the ultrafine bubble layer 100 so as to cover the surface layer of the bottom mud layer 90. That is, by injecting a gas-liquid multiphase flow containing ultra-fine bubbles from each aerator 11 in the horizontal direction, the jet of the gas-liquid multiphase flow containing the ultrafine bubbles diffuses in the horizontal direction as a density flow over a wide range, and the bottom mud layer is formed. An ultrafine bubble layer 100 is formed so as to cover the surface layer 90. The thickness of the ultrafine bubble layer 100 may be appropriately determined in consideration of the thickness of the bottom mud, and is, for example, 10 m or less, preferably about several m, and more preferably about 2 to 3 m. It is preferable that
[0047]
Here, generally, in a closed water area such as a dam reservoir, a density stratification in the vertical direction is easily developed due to, for example, formation of a water temperature stratification. In the water area where such density stratification has developed, the water temperature, density, and other characteristics are uniform in the horizontal direction, and when a discontinuous density gradient or concentration gradient occurs in the horizontal direction, it is made uniform. It is known that the diffusion phenomenon that works is performed. A jet having a certain characteristic penetrates a layer having the same density as the jet and diffuses in the horizontal direction as a density flow.
[0048]
Then, in the method of the present invention, by using the aerator 11 to inject a gas-liquid multiphase flow including ultrafine bubbles generated by pressurized water and oxygen that pressurized the bottom water, the density flow phenomenon in the bottom water is utilized, The ultrafine bubble layer 100 can be formed so as to cover the surface of the bottom mud layer 90 without disturbing the bottom water / sludge layer.
[0049]
Further, in the present embodiment, the oxygen supplied to the aerator 11 is cooled to a temperature equal to the water temperature at the installation depth of the aerator unit 10, so that the density flow phenomenon can be effectively used, and the The fine bubble layer 100 can be formed.
[0050]
The ultra-fine bubbles constituting such an ultra-fine bubble layer 100 have a very large bubble surface area, so that the floating speed of the bubbles is extremely low, and as shown in FIG. The bubble layer 100 stays at that position for a certain period.
[0051]
As described above, since the ultrafine bubble layer 100 covers the bottom mud layer 90 and stays for a predetermined period, oxygen is supplied to the bottom mud layer 90 from the ultrafine bubble layer 100, and the dissolved oxygen is significantly improved. The bottom mud layer 90 is greatly improved and purified. Further, the bottom water is also purified by the fine bubble layer 100 at the same time. Further, by improving and purifying the bottom mud layer 90, deterioration of the quality of bottom water due to the bottom mud layer 90 is also suppressed. Therefore, by improving and purifying the bottom mud layer 90 by the ultrafine bubble layer 100, as a result, the water quality of the entire predetermined water area can be improved.
[0052]
In particular, in the present embodiment, oxygen gas having a concentration of 95% or more is supplied to the aerator 11 using the oxygen generator 20 to generate ultrafine bubbles. The dissolved oxygen in the layer 90 can be reliably increased. For example, when supplying air, the oxygen component ratio is 21%, but by using oxygen gas, the oxygen supply can be increased to about 4.5 times and the gas dissolving efficiency can be further increased.
[0053]
(Embodiment 2)
FIG. 3 is a schematic diagram of a bottom mud improvement / purification device according to the second embodiment.
[0054]
The present embodiment is an example in which a floating unit is connected to an aerator unit instead of the lifting / lowering unit 70, and the aerator unit 10 is arranged at a predetermined position in water by the floating unit.
[0055]
In the present embodiment, as shown in FIG. 3, a floating weight 110 serving as a floating means is connected to the upper side of the aerator unit 10 via a connecting wire 111. Specifically, the aerator unit 10 is fixed to one end of a connecting wire 111 suspended via a pulley 112 provided in the fixing means 60, and a predetermined weight of a lifting weight is attached to the other end. 110 is fixed.
[0056]
Here, the lifting weight 110 has such a weight that a tension is generated such that the aerator unit 10 floats. That is, when the aerator unit 10 and the lifting weight 110 are suspended in the water by the connection wire 111, the lifting weight 110 having a predetermined weight is lowered, so that the aerator unit 10 is pulled up via the connection wire 111. Has become. The aerator unit 10 may be provided with a float member for reducing the underwater load.
[0057]
Further, a fixed weight 120 having a predetermined weight is connected and fixed to the water bottom side of the aerator unit 10 by a fixing wire 121, and the movement of the aerator unit 10 is regulated by the fixed weight 120. The fixed weight 120 preferably has a weight that secures the aerator unit 10 and stably holds it, and preferably has a weight that is heavier than at least the floating weight 110. For example, in the present embodiment, the floating weight 110 weighs about 100 kg, whereas the fixed weight 120 weighs about 200 kg. Therefore, the aerator unit 10 floats as the floating weight 110 sinks as described above, but stops when the fixed wire 121 is fully extended. Thereby, the aerator unit 10 is arranged at a predetermined depth, that is, always at a constant height from the water bottom. This position does not change even if the water surface position changes.
[0058]
In this state, a gas-liquid multiphase flow including ultrafine bubbles is injected from each aerator 11 in the same manner as in the above-described embodiment, and the ultrafine bubble layer 100 is formed so as to cover the surface of the bottom mud layer 90. Then, the bottom mud layer 90 is improved and purified.
[0059]
In such a configuration of the present embodiment, the aerator unit 10 can be easily arranged at a predetermined depth that is not affected by the water surface position, without being fixed to the water bottom. Further, since the aerator unit 10 is merely fixed by the fixed weight 120, it can be easily moved together with the fixed weight 120.
[0060]
In the present embodiment, the levitation weight 110 is connected to the aerator unit 10 as the levitation means, but the levitation means is not particularly limited as long as the aerator unit 10 can be levitated. Absent. For example, as shown in FIG. 4, a float member 130 that generates buoyancy such that the aerator unit 10 can float may be provided above the aerator unit 10. In this case, it is preferable that the aerator unit 10 is moored to the fixing means 60 by the mooring wire 140.
[0061]
Further, in each of the embodiments described above, the example in which the ultrafine bubble layer 100 is formed in one place is described. However, for example, after the ultrafine bubble layer 100 is formed in one place, the fixing unit 60 is moved to a plurality of places. May form the ultrafine bubble layer 100. Thus, the entire bottom mud layer 90 in the predetermined water area can be reliably improved and purified. In addition, this operation may be repeatedly performed so that the ultrafine bubble layer 100 is formed at each location at regular intervals. Thereby, the dissolved oxygen in the bottom mud layer 90 can be greatly increased, and the bottom mud layer 90 can be more reliably improved and purified.
[0062]
Of course, an aerator unit may be installed at each of a plurality of predetermined locations, and an ultrafine bubble layer may be formed at each of the locations. Also in this case, if ultrafine bubbles are formed at regular intervals, the dissolved oxygen can be greatly improved and the bottom mud layer can be surely improved and purified.
[0063]
(Test example)
A large amount of sludge was generated in the uppermost dam reservoir (130m wide and 20m high) in A prefecture, and the area below 2m in depth was anoxic. In the dam reservoir, water temperature stratification was formed from spring to autumn, and large-scale aeration was not possible to stir the entire dam in order to not increase the problem of turbid water during flooding.
[0064]
Then, using an aerator unit as shown in FIG. 3 (with 28 aerators), 95% oxygen was supplied as microbubbles at a depth of 4.5 m at a rate of 30 L / min for about 50 days.
[0065]
As a result, the sludge collected before the supply of the microbubbles consisted of corpse of phytoplankton and clay, had a bad odor of decay, and floated with slight stirring to lower the visibility.
[0066]
On the other hand, in the bottom mud collected after the supply of the microbubbles, the putrefaction odor was reduced and almost disappeared, and no carcass of plankton was observed.
[0067]
FIG. 5 shows micrographs of the sludge before and after the supply of the microbubbles. Before the supply, a mass of clay particles of about 50 μm and a relatively large phytoplankton carcass was observed, but after the supply, clay particles were observed, but the phytoplankton carcass mass disappeared. I was
[0068]
【The invention's effect】
As described above, in the present invention, since a layer of ultrafine bubbles is formed so as to cover the surface layer of sediment deposited on the water bottom, oxygen is effectively supplied from the layer of ultrafine bubbles to the bottom mud. Can be supplied, and the bottom mud can be greatly improved and purified.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a bottom mud improving / purifying apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating a method of improving and purifying bottom mud according to one embodiment of the present invention.
FIG. 3 is a diagram schematically showing a bottom mud improving / purifying apparatus according to another embodiment of the present invention.
FIG. 4 is a view schematically showing a bottom mud improving / purifying apparatus according to another embodiment of the present invention.
FIG. 5 is a micrograph showing a result of a test example of the present invention.
[Explanation of symbols]
10 Aerator unit
11 Aerator
12 Pressure pump
13 Pressure water piping
14 Air header
15 Air supply piping
20 oxygen generator
30,31 compressor
40 power supply
50 Cooling device
60 fixing means
70 Lifting means
110 Lifting weight
112 pulley
120 fixed weight
130 Float member

Claims (10)

Forming a layer of ultrafine bubbles made of at least oxygen-containing gas so as to cover the surface layer of sediment deposited on the bottom of the water at a predetermined depth, supplying oxygen to the sediment from the layer of ultrafine bubbles, and A method for improving and purifying bottom mud, comprising improving and purifying mud. 2. The method according to claim 1, wherein the gas is an oxygen gas having a concentration of 95% or more. 3. The method for improving and purifying bottom mud according to claim 1, wherein the gas is cooled to a temperature about the water temperature at the predetermined depth. 4. The method for improving and purifying bottom mud according to any one of claims 1 to 3, wherein the bottom mud deposited on the bottom of the closed natural waters is improved and purified. An oxygen gas generator for generating a predetermined concentration of oxygen gas, and an oxygen gas supplied from the oxygen gas generator, which is arranged at a predetermined depth near the surface layer of sediment deposited on the bottom of the water and is horizontally injected as ultrafine bubbles. And an aerator unit having a plurality of aerators. The apparatus for improving and purifying sediment according to claim 5, wherein the oxygen concentration of the oxygen gas is 95% or more. 7. The improvement of bottom mud according to claim 5 or 6, further comprising a cooling device for cooling the oxygen gas, wherein the ultrafine bubbles injected from the aerator are cooled to a water temperature at the predetermined depth.・ Purification device. The aerator unit according to any one of claims 5 to 7, wherein the aerator unit is connected to a fixed weight disposed on the bottom of the water, and levitation means for lifting the aerator unit is connected, and the aerator unit is connected to the predetermined weight via the fixed weight. A bottom mud improvement / purification device, which is fixed at a position. 9. The floating means according to claim 8, wherein the floating means is provided at the other end of a connecting wire which is connected to the aerator unit at one end and is turned back via a pulley fixed to a mooring member moored at the water surface, and is suspended underwater. A sludge improving / purifying apparatus characterized in that it is a floating weight having a predetermined weight. 9. The apparatus for improving and purifying bottom mud according to claim 8, wherein the levitation means is a float member that is also provided in the aerator unit and generates buoyancy to the extent that the aerator unit can float.

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