JPH063013B2 - Water-bottomed sand covering method with plowing and its equipment - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for cultivating a bottom of a sea with plowing for improving the water quality of rivers, lakes, seas, etc., and recovering the biota of aquatic organisms, and an apparatus thereof. is there.

[Prior art]

Organic substances are deposited on the bottom of the water due to eutrophication of water quality in rivers, lakes, seas, etc., which has a significant impact on the fishing industry and the recreation industry such as nutrient salt elution, red tide generation due to hypoxia, and reduction of bottom organisms. What is given is already well known, and this phenomenon has become a problem that requires an urgent solution socially as an environmental problem.

As described above, the most effective method for removing the organic sludge accumulated on the bottom of the water is to remove it.For this purpose, sludge dredging is planned or carried out in rivers, lakes, seas, etc. where eutrophication is progressing. It has been implemented.

However, when sludge is dredged and removed, a disposal site for the removed sludge is required, and in an area where an appropriate disposal site is not required, this problem has become an obstacle and measures against organic sludge have been stalled. There are many.

Therefore, in such a place, a so-called sand-covering method, in which the organic sludge deposited on the bottom of the water is covered with high-quality sand, is performed as an alternative to the dredging removal.

This is to provide a place for algae and fry breeding and spawning by preventing nutrient salts from leaching by covering with sand of high quality organic sludge and by ensuring fresh bottom sediment. It is possible.

On the other hand, the organic sludge deposited on the bottom of the water belongs to the soft mud as a classification of soil, its properties are soft, and the thickness of its deposited layer is relatively thin, and many are widely and thinly deposited on the bottom of the water. An example of the work situation of the sand-covered work ship by the sand-covering method conventionally performed on such a water bottom will be described with reference to FIG.

In FIG. 3, when the organic sludge layer 3 widely and thinly deposited on the upper layer of the water bottom portion 2 of the water body 1 having an appropriate water depth such as a river, lake or sea is covered with sand, Ship 5
Stores the sand for covering sand supplied from the outside by a suitable method in the sand storage tank 6 in the ship, and guides it to the water bottom directly or through a chute-shaped conduit 7 reaching near the water bottom by mixing with water, As shown in the figure, the sand cover work vessel 5 is appropriately moved so that a thin sand cover layer can be formed, and the sand cover work is performed.

The bottom layer formed as a result has a thin layer of high-quality sand in the upper part and the organic sludge in the lower part, and the high-quality sand layer in the upper part contains nutrient sludge from the lower part by containing the organic sludge. It is possible to create a state of enriched oxygen capable of habitat of benthic organisms by preventing the elution of water and forming a water bottom surface with sufficient water permeability. As described above, the conventional sand-covering method is configured to place sand on sludge, but by further plowing this organic sludge, water is mixed into the accumulated organic sludge, Further, the surface layer and the lower layer of the organic sludge can be replaced with each other, and such plowing is very generally performed even in the soil where the agricultural products are cultivated for the purpose of supplying water and air into the soil. However, a similar effect can be expected for organic sludge deposited on the bottom of the water.

In addition, the surface of organic sludge generally has a high content of COD, phosphorus, nitrogen, etc., is poorly oxygenated, and is often in the form of sludge that is extremely soft as a soil property. By cultivating the soil, it is possible to transfer most of the nutrient salts from the surface of the sludge to the lower layer by displacing the soil in the lower layer, which is relatively low in nutrient salt and not soft, and to move the relatively soft soil to the surface. By doing so, it becomes possible to create a soil condition in which sand is easily covered.

The present invention was made by paying attention to the combined use of the plowing method, which has the above-mentioned effects, in addition to the conventional sand-covering method which is generally carried out as described above.

[Object of the Invention]

The present invention, as described above, by covering the organic sludge layer of the bottom of the water with good quality sand, prevents the elution of nutrients, and at the same time secures fresh bottom material on the bottom of the water, and further cultivates the organic sludge layer. The purpose is to restore the biota of the aquatic organisms by replacing the surface layer with the lower layer.

[Structure of Invention]

In order to achieve the above-mentioned object, the water bottom sand cover construction method with tillage of the present invention is characterized in that it is accompanied by tillage when sand covering the sludge layer of the water bottom, and the water bottom sand cover device is a cover. At the bottom of the chute-shaped sand supply conduit that was guided from the sand work boat to the sludge layer at the bottom of the water, a cultivator capable of cultivating the sludge layer was installed, and before and after the cultivating device, the sand from the conduit was used. Is provided by arranging two sand-supplying sand-supplying sand supply pipes capable of supplying either one or both of them via a distribution valve.

Further, as a combination when using the sand cover of the water bottom sludge layer and cultivating together, (1) a method of covering sand after cultivating, (2) a method of cultivating simultaneously with covering sand and ( 3)
It is possible to select from three types of construction methods in which sand is covered and then sand is covered.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view for explaining the working condition of a sand cover work ship in one embodiment for a water bottom sand cover construction method with tillage used in the sand cover construction method of the present invention. The basic structure of the part that supplies sand to the bottom of the work boat 5 is
It is the same as the conventional sand-covering work vessel 5 shown in FIG. 3, and the same parts are denoted by the same part numbers in each drawing, and the sand for sand-covering is guided to the bottom of the water through a chute-shaped conduit 7.

Therefore, the chute-shaped conduit 7 of FIG. 1 is equipped with a sand covering device 8 with plowing, which is a feature of the present invention, and is an enlarged detailed side sectional view of the sand covering device 8 with plowing. The sand covering device 8 for cultivating shown in the figure is provided with a cultivating device 9 installed inside and sand supply pipes 10 and 11 for sand covering sand installed in the front-rear direction outside, respectively. The supply pipes 10 and 11 and the chute-shaped conduit 7 shown in FIG. 1 supply the sand for sand covering supplied from the chute-shaped conduit 7 to one or both of the sand-supplying sand supplying pipes 10 and 11. Connected via the distribution valve 12 as possible, the distribution valve 12
A fixed partition wall 13 is provided in the lower part of the.

In addition, in FIG. 2, after performing the plowing while performing the covering sand which is the third construction method among the three kinds of combinations when the covering sand and the plowing are used together, the sand covering device 8 accompanied by the plowing is shown in FIG. The implementation status is shown when covering the sludge layer with sand.

That is, in FIG. 2, when the work is carried out while moving the sand covering device 8 with cultivating from the left to the right in the figure, the organic sludge layer 3 deposited on the water bottom passes through the sand covering device 8 with cultivating. While mixing the sand supplied from the sand-covering sand supply pipe 11 attached to the outside front of the sand-covering device 8 into the organic sludge layer 3 by the tilling device 9 mounted inside the sand-covering device 8, It is possible to cultivate.

Then, as shown in FIG. 2, the cultivated sludge after cultivating is covered with sand supplied from the sand-supplying sand supply pipe 10 attached to the outside rear of the sand-covering device 8, and this method of construction is used. At the same time as the intended sand covering is performed, it becomes possible to cultivate and subsequently cover the sludge layer with sand.

In this case, the distribution valve 12 for distributing the sand-covering sand is set so as to distribute the sand to both the sand-covering sand supply pipes 10 and 11.

If the distribution valve 12 is set so that the sand is supplied only to the front sand-covering sand supply pipe 11 by the similar construction method, the second construction method is the second construction method of the combination when the sand-covering sand and the plowing are used together. At the same time, a construction method for plowing becomes possible, and conversely the distribution valve 1
If 2 is set so that the sand is supplied only to the rear sand-covering sand supply pipe 10, the first construction method of the combination in the case of using the sand-covering sand and the tillage together is performed, and then the sludge layer is overlaid. It becomes possible to construct a method to cover the sand.

Therefore, depending on how the distribution valve 12 is set as described above, in the case of the three construction methods in which sand covering and plowing are used in combination,
Any construction method can be selected by simply changing the supply of sand using the same device.

Which of the first, second, and third construction methods is selected may be selected depending on the properties of sludge, the expected effects of plowing and sand cover, and the cost.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, according to the present invention, in order to more effectively prevent the elution of nutrient salts of organic sludge layers deposited on the bottom of rivers, lakes, seas, etc. This is a method that uses plowing in combination with the construction method. If you use the method of covering sand after performing plowing, which is the first construction method that also uses plowing and covering sand, water or oxygen will be supplied by plowing and the surface and lower layers The effect such as substitution can be expected, and the effect of containing sludge can be expected by covering the layer of sludge with sand after that.

Moreover, if the method of plowing at the same time as the second method of covering sand is adopted, by supplying high-quality sand into the sludge at the same time as plowing, along with the general effect of plowing,
The effects of sand such as water permeability and gap retention can be expected in parallel, and if the method of covering sand after cultivating while covering the sand, which is the third method, is used, the second method described above is used. In addition to the effect of the construction method, the effect of containing sludge can be expected.

Incidentally, as an application field of the present invention, for example, organic sludge, of course, in the sludge containing harmful substances, etc., for the purpose of solidifying or neutralizing it at the bottom of the water, a solidifying agent,
Even when adding a neutralizing agent, etc., it is possible to achieve the object with a similar technical configuration by using a stirring and mixing machine instead of the cultivator, and stirring the sand-covered construction method with cultivating of the present invention. It can be easily applied as a chemical addition method involving mixing.

[Brief description of drawings]

FIG. 1 is a side view for explaining the working condition of a sand-covered work ship in one embodiment of a water-bottomed sand-covering method involving tillage used in the present invention,
FIG. 2 is an enlarged detailed side view of the sand covering device with tillage of FIG. 1, and FIG. 3 is a side view for explaining the working condition of the conventional sand covering work ship for the bottom sand covering method. 3 ... Organic sludge layer, 4 ... Sand cover, 5 ... Sand cover work vessel, 7 ... Conduit, 8 ... Sand cover device, 9 ... Plowing device, 10, 11 ... Sand cover sand supply pipe, 12 ... Distribution valve.

Claims (5)

[Claims] 1. A water-bottom sand cover construction method that involves plowing when sand-covering a sludge layer on the water bottom. 2. The method for covering water bottom with plowing according to claim 1, wherein sand is covered after plowing the sludge layer at the bottom of the water. 3. A method for covering water bottom with plowing according to claim 1, wherein plowing is performed at the same time as sand covering the sludge layer on the bottom of the water. 4. The method for covering a bottom of water with plowing according to claim 1, wherein the sludge layer on the bottom of the water is covered with sand and then covered with sand. 5. A cultivator capable of cultivating a sludge layer is provided below a chute-shaped conduit for sand supply that is guided from a work vessel for covering sand to a sludge layer on the water bottom, and before and after the cultivator. , Either of the sand from the conduit via a distribution valve,
Alternatively, a water bottom sand cover device with cultivating, which is provided with two sand supply sand cover pipes capable of supplying both.