JP3899385B2 - Method of improving mud and water quality in tidal river and seepage column used for this - Google Patents

Description

  The present invention relates to a tidal river that improves the river environment by purifying the nature of the bottom mud (hereinafter referred to as “mud”) and the water quality of the river water accumulated in the tidal river by using the tide of the tidal river. It is related with the improvement method of mud and water quality and the penetration column used for this.

  The tidal flats in the tidal area of a river with tides are caused by organic mud that has formed in the sea when the river flow is low, causing sedimentation, and mudification proceeds near the estuary. ing. When mudification of such tidal flats progresses, the water circulation inside the sediment is hindered, the internal load increases, the supply of harmful substances such as sulfides decreases, the river purification function decreases, the biological habitat environment deteriorates and the waterside landscape This leads to loss of value. Thus, dredging etc. can be cited as a countermeasure against environmental deterioration caused by sedimentary mud, but disposal of dredged soil has become difficult, and new technological development is required.

Therefore, various techniques for purifying the water quality of rivers have been proposed. For example, as shown in Japanese Patent Application Laid-Open No. 5-131196 “Environmental Purification Structure” of Patent Document 1, a natural polluted water environment is generally in an acidic state. By installing an environmental purification structure filled with alkaline solid particles (mineral, coal ash, cement lanceance, etc.) in a water-permeable frame, the alkali content in shells and alkaline solid particles is dissolved in water. A technology has been proposed to purify the water quality environment such as seas, harbors, rivers, marshes, ponds, dams, etc. by neutralizing and mitigating the contaminated water in an acidic state.
Moreover, this patent document 1 also discloses that useful microorganisms and small animals having a water purification action can inhabit and multiply on the surface of shells and alkaline solid particles to further promote the water purification action.
JP-A-5-131196

As disclosed in Japanese Patent Application Laid-Open No. 10-15538, “Improvement of sediment and water quality and method of breeding benthic animals using the same”, an absorbent of ammonia nitrogen, nitrite nitrogen, phosphate phosphorus and By adding the heat-treated shell fossils to the bottom of the water, the sediment and water quality in the vicinity are quickly attenuated, thereby improving the bottom and water quality and creating a good environment for benthic animals. The technology to make it appear is proposed.
Japanese Patent Laid-Open No. 10-15538

As shown in Japanese Patent Application Laid-Open No. 2001-29951 “Method for purifying sea area with coal ash artificial zeolite”, artificial zeolite obtained by subjecting coal ash to hydrothermal chemical treatment is used as an upper part of the bottom sediment mud layer in the sea area. A technique for preventing water pollution caused by eutrophication with nutrient salts and gas in closed sea areas such as inner bays has been proposed.
JP 2001-29951 A

  However, the techniques disclosed in Patent Documents 1, 2, and 3 submerge modified materials such as a mud / water quality improver in water or in the sea for the purpose of improving water quality and mud quality. All of these modifying materials were installed or spread on the surface of the river bed or the surface of the seabed. Therefore, it is possible to improve the mud quality of only the surface layer of the riverbed or the seabed together with the water quality. However, in such an improvement method, oxygen cannot be sufficiently supplied into the bottom mud, so that the modification or improvement in the bottom mud cannot be achieved, and the bottom quality and biological habitat environment cannot be improved. was there.

  In addition, the modified material installed or sprayed on the surface of the riverbed or the seabed in this way is easily recognized by the surrounding residents as improving the river or seawater. The number of people playing in water was decreasing in rivers and coasts. Furthermore, the modified material thus installed or dispersed has a problem that it is easily damaged by humans.

  The present invention has been developed to solve such problems. That is, an object of the present invention is to embed a material for improving water quality and mud in the river bed, to utilize the tide of a tidal river, improve the river sediment by supplying oxygen to the bottom mud and The emergence of a good habitat for benthic organisms that induces the purification action, which can promote the improvement of the bottom sediment of the riverbed, and there are no protrusions or foreign objects on the surface of the riverbed. The purpose is to provide a method for improving the mud and water quality of tidal rivers and the infiltration columns used for this.

According to the improvement method of the present invention, it is a method for improving the mud quality and water quality of a tidal river (2) where there is tidal flow, and is capable of insolubilizing and immobilizing sedimentary mud (4) and phosphorus in water. The modified material is penetrated from the sedimentary mud (4) in the river bed (3) of the tidal river (2) to the sand layer (5) below the modified mud, and the inside of the modified material is utilized by utilizing the tidal flow. A method for improving the tide and water quality of a tidal river is provided, wherein the water is circulated and oxygen is supplied to the sedimentary mud (4) to improve the quality and quality of the river. .
For example, a vertically long embedding hole is opened vertically on the surface of the river bed (3) of the tidal river (2) at a predetermined interval, and the modified material is embedded in each embedding hole.

It is preferable to embed the modified material in the river bed (3) so that the upper part is in the vicinity of the surface of the accumulated mud (4) accumulated in the river bed (3) of the tidal river (2).
It is preferable to spray sand covering (6) on the river bed (3) so as to cover the upper part of the modified material embedded in the river bed (3).
The mud generated when the buried hole is dug together with the coal ash granulated material having a reforming function can be used for the sand covering (6) sprayed on the river bed (3).

  According to the osmotic column of the present invention, the osmotic column (1) improves the mud quality and water quality of the tidal river (2) where there is tides, insolubilizes and immobilizes the bottom mud and phosphorus in the water, and To improve the mud and water quality of a tidal river, which is made of a material with good water permeability and has a vertically long column shape so that it can be embedded vertically in the surface of the river bed (3). An osmotic column for use is provided.

The penetration column (1) has a substantially cylindrical shape.
The penetration column (1) is a solid particle such as gravel.
The permeation column (1) is an alkaline solid particle.
The permeation column (1) is a coal ash material which is obtained by adding coal ash to a main material and granulating it.
The osmotic column (1) is recovered when the effect of insolubilization / immobilization of the phosphorus is saturated, and the recovered osmotic column (1) can be used as a permeable civil engineering material. It is possible to use a solidified main material such as.

  In the improvement method of the above configuration, the modified material () having good water permeability is buried so as to penetrate from the accumulated mud (4) in the bed (3) of the tidal river to the sand layer (5) below it. Due to the tide of the tidal river, more oxygen is supplied to the sedimented mud (4), and the reduced state of the deposited mud (4) is eliminated. Thereby, generation | occurrence | production of hydrogen sulfide is suppressed, and nitrogen in sedimentation mud (4) can be removed because sedimentation mud (4) will be in an aerobic state. In addition, it is possible to bring out a good habitat for living organisms that induce the purification action of bottom mud in and around the sedimentary mud (4) and the mud / water quality improvement cylinder, and further improvement of mud quality is promoted. Can improve sediment quality and biological habitat.

  By spreading sand cover (6) on the river bed (3) so as to cover the upper part of the modified material, the physical and attractive environment of the river (1) can also be improved. It becomes easier for people to play in the river (1).

In the permeation column having the above-described structure, the alkaline solid granules and the coal ash granule have not only the improvement of the bottom sediment because they have the ability to fix phosphorus in the sediment mud (4), but also the sediment mud (4 ) Immobilization of phosphorus contained therein can suppress elution of phosphorus into water and improve the water quality of the river (1).
By using the coal ash granulated material as the raw material for the permeation column (1), it is possible to effectively utilize the coal ash generated from the thermal power plant.
The permeation column (1) in which the immobilization ability of phosphorus is saturated can be recovered, and the recovered permeation column (1) can be used as, for example, a water-permeable civil engineering material, so that resources can be effectively used.

  The method for improving the tide and water quality of a tidal river according to the present invention is a method for improving the quality and quality of a tidal river in a tidal river with tides, insolubilizing and fixing sedimentary mud and phosphorus in the water. The modified material (permeation column) that has become water-permeable and penetrates from the sedimentary mud in the riverbed of the tidal river to the sand layer below it, circulates water in the modified material using the tidal flow, This is a method to improve the quality of river mud and water by supplying oxygen to sedimentary mud.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram for explaining a method for improving mud and water quality of a tidal river in Example 1 of the present invention.
As shown in FIG. 1, the method for improving the mud and water quality of a tidal river of the present invention is applied to the river bed 3 of the tidal river 2 where the tides are filled with the infiltration column 1 which is a highly permeable modified material. A large number are buried. In particular, the infiltration column 1 is buried so as to penetrate from the accumulated mud 4 in the bed 3 of the tidal river 2 to the sand layer 5 therebelow.

  Further, the infiltration column 1 is embedded so that the upper portion 1a is in the vicinity of the surface of mud such as a sludge layer accumulated in the river bed 3. As a result, the water of the river 2 containing dissolved oxygen due to the tide effectively passes through the infiltration columns 1 of the present invention, and oxygen is supplied to the sedimented mud 4 through the infiltration columns 1 at low tide. it can.

  The penetrating column 1 of the present invention has a substantially cylindrical shape, and an effective reforming range can be obtained by arranging the penetrating columns 1 so as to be staggered at a predetermined interval along the shore of the river 2. For example, in the permeation column 1, a vertically long embedding hole (not shown) is formed vertically on the surface of the river bed 3 of the tidal river 2 at a predetermined interval, and the permeation column 1 is embedded in each embedding hole.

  The sand cover 6 is sprayed on the river bed 3 so as to cover the upper part 1a of the seepage pillar 1 which is a modified material embedded in the river bed 3 (see FIG. 4). The sand covering 6 has a function of improving the physical and attractive environment of the river 2. There is an effect that it becomes easy for a person to play in the water in the river 2. The sand covering 6 can utilize the mud generated when the buried hole is dug together with the coal ash granule having a reforming function.

  As a reforming material for the permeation column 1, an alkaline substance such as coal ash, red clay, calcium carbonate or the like as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 5-131196) is used with a small amount of a binder such as cement. What is hardened and granulated can be used. By using the coal ash granulated material as shown below, the coal ash can be effectively utilized.

  Coal ash granulated material is obtained by, for example, mixing 100% combustion ash (hereinafter referred to as “fluidized bed ash”) of coal-fired fluidized bed thermal power plant and 15% water (relative to fluidized bed ash). Manufactured by a granulation method to make particles having a diameter of 10 to 15 mm.

Moreover, the coal ash granulation used as the raw material of the osmosis | permeation pillar 1 shows the phosphorus removal performance in the bottom mud by the coal ash granulation using fluid bed ash, and is excellent in phosphorus removal performance. This coal ash granulation is more effective than phosphorus ash, which is a raw material, as compared with the conventional measures to cover with laid sand in eutrophic waters. Material. Therefore, compared to natural sand, it has the ability to prevent elution into water by immobilizing phosphorus that causes red tides.
In addition, coal ash granulated material using fluidized bed ash is also a safe material that satisfies all the environmental items of the “environmental standards related to marine pollution”.
Furthermore, the coal ash granule using fluidized bed ash is a material that is easy to handle and can maintain a stable shape for a long time.

As described above, the method for improving the mud and water quality of the tidal river according to Example 1 and the infiltration column 1 used therefor have the following mud and water quality improving effects.
(1) Effect of improving mud quality (a) Since the flow of water containing dissolved oxygen can be generated in each infiltration column 1 by tide, or at low tide, the accumulated mud 4 is passed through each infiltration column 1 Since oxygen can be supplied, the reduced state of the bottom mud can be eliminated.
(B) By supplying oxygen to the deposited mud 4, generation of hydrogen sulfide and the like can be suppressed, and sludge formation of the deposited mud 4 can be prevented.
(C) Since a good habitat environment for benthic organisms can appear, the range of modification can be expanded synergistically.
(D) By supplying oxygen to the deposited mud 4, the deposited mud 4 becomes aerobic and nitrogen and the like can be removed. Further, by using alkaline solid particles or coal ash granulated material, the phosphorus in the sedimentary mud 4 is fixed, and the elution of phosphorus into the river 2 water can be suppressed.
(2) Water quality improvement effect (a) Since nitrogen and the like are removed by eliminating the reduced state of the accumulated mud 4, elution into the river 2 water can be suppressed.
(B) By using alkaline solid granules or coal ash granulated material for the permeation column 1, phosphorus can be immobilized, so that elution of phosphorus into the river 2 water can be suppressed, Immobilization of phosphorus can be achieved.

  Moreover, when using an alkaline solid granule or a coal ash granulated material, it can collect | recover the osmosis | permeation pillar 1 in which the effect of the fixation of phosphorus was saturated, and can replace | exchange easily for the new osmosis | permeation pillar 1, The permeation column 1 thus made can be used as, for example, a water-permeable civil engineering material.

[Experimental Example 1]
Next, Experimental Example 1 conducted for examining the effectiveness of the method for improving the mud and water quality of the tidal river of the present invention will be described.
FIG. 2 is a plan view showing the Tenman River used in Experimental Example 1. FIG. FIG. 3 is a schematic diagram showing the experimental area. FIG. 4 is a diagram comparing the color state of the tidal flat 2 months after the construction of the penetrating column of the present invention. FIG. 5 is a graph showing changes in the hardness and hardness of the sand cover. FIG. 6 is an explanatory diagram showing a change state of the bottom product. FIG. 7 is an explanatory view showing a change state of the water quality of pore water. FIG. 8 is an explanatory diagram showing a change state of the particle size of the mud layer.
(1) Outline of the experimental site In Experimental Example 1, the Otagawa-shi Tenkawa River Tenmagawa River Distance Mark, which runs through the city of Hiroshima City, was conducted at a distance of 3.0 km (deposition of mud was about 40 cm).

(2) Outline of the experimental area In the experimental area, as shown in FIG. 3, the experimental area 1 for the purpose of grasping the hydrophilic improvement effect by spraying the sand covering 6 on the infiltrating pillar 1 and the infiltrating pillar 1 An experimental area 2 was constructed for the purpose of grasping the bottom sediment improvement effect.

(3) Monitoring method Monitoring has been conducted once a month since June 2004. In Experiment Zone 1, the color, thickness and hardness of sand-capped sand 6 were measured, and in Experiment Zone 2, pore water quality was investigated. During the same period, surveys of sediment and benthic organisms were conducted three times in June, August, and November.

(4) Survey results (1) Examination results of sand-capping effect Comparison of the color of sand-capped sand 6 and the local tidal flat 2 months after construction is shown in Fig. The color changed from gray to yellow, and it is thought that visual improvement was achieved.

  As shown in FIG. 5, the changes in hardness and thickness were 10 to 20 times higher in hardness at both points in the construction 2 months than in the construction (hardness 5 kg / cm 2). Compared to local tidal flats (hardness less than 1kg / cm2), it became easier to walk. Moreover, the thickness of the sand covering 6 was a reduction | decrease amount of about 1-2 cm from the time of construction.

(2) Improvement effect of bottom sediment by seepage column As shown in Fig. 6, the number of confirmed species did not change in the comparison plot, but the number of confirmed species was 3 to 6 around the seepage column 1. Increased to. In the comparative plot, there is a bias in the species, but many crustaceans such as tiger crabs are found around the permeation column 1 and it is considered that the environment is easy to live.

As changes in the sediment environment, the change in pore water quality is shown in FIG. 7, and the change in particle size of the mud layer is shown in FIG. However, after 3 months, the mud layer around the permeation column 1 showed a low value. Nitrate nitrogen + nitrite nitrogen tended to be lower with increasing distance from the permeation column.
The mud layer particle size of 75μ or less decreased to 5.6% around the permeation column and 3.7% in the comparison plot, and the amount of decrease was large around the permeation column 1. Moreover, the ORP of the bottom sediment showed an improvement tendency of about +120 mV around the permeation column 1 from the comparison plot. In the explanatory diagram of FIG. 8, the comparative section is located at a position slightly away from the permeation column 1 as shown in FIG. 3, and is not a position where the influence of the permeation column 1 does not reach at all.
From the above, it is considered that oxygen can be supplied into the bottom mud, and the sediment and biological habitat environment are improved.

  In the present invention, by embedding the infiltration column 1 in the riverbed 3, the bottom that induces the improvement of the bottom quality of the river 1 and the purification of the bottom mud by supplying oxygen to the bottom mud using the tide of the tidal river 1. The present invention is not limited to the embodiment of the present invention as long as it can promote the improvement of the bottom sediment of the river bed by the appearance of a good habitat of the organism, and the method of arranging the seepage pillar 1 on the river bed 3 is as follows. It is not restricted to the method mentioned above, You may arrange | position with arbitrary patterns. Further, the permeation column 1 has a substantially cylindrical shape, but the shape may be any shape such as a rectangular column or a conical shape, and it goes without saying that various changes can be made without departing from the scope of the present invention.

As described above, according to the method for improving the mud and water quality of the tidal river of the present invention and the infiltration column used therefor, the deterioration of water quality and bad odor caused by the accumulation of sludge that is a problem in urban rivers. Occurrence, loss of waterside landscape value and separation of people from the waterside, decline in human mobility, and inhibition of urban activation can be prevented.
Moreover, the coal ash generated from the thermal power plant can be effectively utilized by using the coal ash granulated material as the raw material of the permeation column.

It is the schematic explaining the improvement method of the mud and water quality of the tidal river of Example 1 of this invention. It is a top view which shows Tenma River utilized for Experimental example 1. FIG. It is a schematic diagram which shows an experimental area. It is the figure which compared the color state of the tidal flat 2 months after construction of the penetration pillar of this invention. It is a graph which shows the change of the hardness and hardness of sand covering. It is explanatory drawing which shows the change state of a bottom product. It is explanatory drawing which shows the change state of the water quality of pore water. It is explanatory drawing which shows the change state of the particle size of a mud layer.

Explanation of symbols

1 Permeation column (modified material)
1a Upper part of seepage column 2 Tidal river 3 River bed 4 Mud deposit 5 Sand layer 6 Covered sand

Claims (11)

It is a method to improve the mud and water quality of the tidal river (2) where there is tides,
A water-permeable modified material capable of insolubilizing and fixing phosphorus in the sedimentary mud (4) and water is obtained from the sedimentary mud (4) in the bed (3) of the tidal river (2) and the sand layer (5) below it. Intrude,
The tide is characterized in that water is circulated in the reforming material by utilizing the tidal range of the tide, and oxygen is supplied to the sedimentary mud (4) to improve the quality and quality of the river. How to improve river mud and water quality. The surface of the river bed (3) of the tidal river (2) is formed with vertically long embedded holes at predetermined intervals, and the modified material is embedded in each embedded hole. How to improve mud and water quality in tidal rivers. The modified material is embedded in the river bed (3) so that the upper part thereof is near the surface of the sedimented mud (4) accumulated in the river bed (3) of the tidal river (2). A method for improving the mud and water quality of a tidal river according to claim 1 or 2. The tidal river according to claim 1, 2 or 3, wherein sand covering (6) is sprayed on the river bed (3) so as to cover the upper part of the reformed material embedded in the river bed (3). How to improve mud and water quality. 5. The mud generated when the buried hole is dug is used together with the coal ash granulated material having a reforming function in the sand covering (6) sprayed on the river bed (3). How to improve the mud and water quality of tidal rivers. An infiltration column (1) that improves the mud and water quality of a tidal river (2) with tides,
Made of insolubilized and immobilized sedimentary mud (4) and phosphorus in water, and made of a material with good water permeability,
An infiltration column used for improving mud and water quality of a tidal river, characterized by having a vertically long and substantially columnar shape so as to be embedded in the surface of the river bed (3) in the vertical direction. The permeation column (1) used in the improvement of the mud and water quality of a tidal river according to claim 6, wherein the permeation column (1) has a substantially cylindrical shape. The osmotic column (1) used for improving the quality of mud and water of a tidal river according to claim 6 or 7, wherein the osmotic column (1) is a solid granule such as gravel. The osmotic column (1) is an alkaline solid granule, wherein the osmotic column is used for improving mud and water quality of a tidal river according to claim 6 or 7. The osmotic column (1) is a coal ash material obtained by adding coal ash to a main material and granulating it by a granulation method. Penetration column used to improve The osmotic column (1) is collected when the effect of insolubilization / immobilization of the phosphorus is saturated, and coal ash or the like is used so that the collected osmotic column (1) can be used as a permeable civil engineering material. The infiltration column used for improving the mud and water quality of the tidal river according to claim 10, wherein the main material is solidified.