Solid material for forming seaweed bed

Abstract

A solid material 1 for forming a seaweed bed is composed of a material in which sewage sludge char 2, steelmaking slag 3 which has a large particle diameter, steelmaking slag 4 which has a small particle diameter, and activated carbon 5 to which fulvic acid has been adsorbed are solidified into a mass using cement 6. The activated carbon is formed by carbonizing and activating waste plastics or waste clothing.

Description

Solid for seaweed bed formation

[0001] The present invention relates to a solid for seaweed bed formation.

[0002] In recent years, in the rocky reef and boulder areas of the coastal waters of Japan, a phenomenon called "rock burning" has occurred frequently, in which seaweed (sea grass) beds where seaweeds reproduce have significantly declined and disappeared, and the reduction of coastal fishery resources such as kelp, abalone, and turban shell has become remarkable.

[0003] One of the causes of "rock burning" is that (divalent) iron ions necessary for the growth of seaweed (sea grass) may be insufficient.

[0004] That is, seaweed (sea grass) cannot decompose and absorb elemental iron, and absorbs iron only in the form of iron ions. On the other hand, the iron ions contained in coastal waters are supplied by the inflow of water-soluble iron humate, especially iron fulvate, generated in the forest humus soil, together with river water, from the mountains to the sea. However, due to the recent deforestation, construction of sediment control dams, etc., the supply amount of iron fulvate in coastal waters has significantly decreased, which is considered to be the cause of "rock burning".

[0005] In the prior art, a water environment conservation material manufactured by mixing a fermented humic acid supply substance (for example, humus such as waste wood chips, fallen leaves, and sewage sludge) with an iron-containing substance (for example, steelmaking slag) is filled into a plurality of cloth bags, and those cloth bags are housed in a steel container and then submerged in the sea to continuously generate iron fulvate and supply iron ions to the water area, thereby forming a seaweed bed (for example, Patent Document 1, etc.).

[0006] However, according to this method, since a mixture of humus directly mixed with steelmaking slag is filled into a cloth bag and housed in a steel container, iron fulvate elutes into the water area in a relatively short period, and iron ions cannot be stably supplied over a long period.

[0007] In addition, the surface of the steel container is flat and does not have irregularities for seaweed (sea grass) to settle and reproduce, so it is not suitable for the formation of a seaweed bed.

[0008] Furthermore, humus contains not only humic acids such as fulvic acid, but also large amounts of organic matter that causes red tides. This organic matter flows into the water, causing red tides, which negatively impacts the formation of seaweed beds.

[0009] Japanese Patent Publication No. 2016-194195

[0010] Therefore, the object of the present invention is to provide a solid material for seaweed bed formation that can generate iron fulvic acid over a long period of time, thereby stably supplying iron ions to the water body and is suitable for the establishment and propagation of seaweed (seagrass).

[0011] To solve the above problems, the present invention provides a solid material for forming seaweed beds, characterized in that carbonized sewage sludge and an iron-containing substance are solidified into a permeable mass by a binder.

[0012] The solid material for seaweed bed formation only needs to be in the form of lumps; its shape and size are not limited. Furthermore, the average particle size of the sewage sludge and iron-containing material, and the mixing ratio of the sewage sludge, iron-containing material, and binder, are determined according to the environment in which the solid material for seaweed bed formation is used. In this case, the hardness of the solid material for seaweed bed formation changes depending on the proportion of binder in the whole material (the higher the proportion of binder, the harder the solid material becomes).

[0013] In the above configuration, the iron-containing material is preferably one or more of the following: iron powder, iron oxide powder, and slag, and the slag is preferably composed of large-particle steelmaking slag and small-particle steelmaking slag. Furthermore, the binder is preferably cement, and more preferably the cement is blast furnace cement, permeable cement, or a combination thereof.

[0014] In the above configuration, preferably, the solid material for seaweed bed formation further contains polyglutamic acid.

[0015] Preferably, the solid material for forming the seaweed bed further contains activated carbon that has adsorbed fulvic acid. The activated carbon is preferably made from material formed by carbonizing and activating waste plastic or waste clothing.

[0016] More preferably, the solid material for seaweed bed formation further includes reinforcing members made of carbon fibers and / or FRP carbonized material. The carbon fibers are preferably recycled carbon fibers, and the reinforcing members may be multiple carbon fibers themselves, or multiple carbon fibers solidified into a rod or plate shape. The FRP carbonized material is preferably obtained by carbonizing waste FRP products such as discarded FRP fishing boats.

[0017] Furthermore, the solid material for seaweed bed formation may also include a carbonizing agent, or carbonized waste plastic or carbonized waste clothing, or powdered carbonized seashells and / or crustaceans, or dried sewage sludge, or a combination of two or more of these. The average particle size and weight ratio of each of these additional materials to the solid material for seaweed bed formation will be determined according to the environment in which the solid material for seaweed bed formation is used.

[0018] The solid material for seaweed bed formation may, for example, have the form of gravel with an average particle size of 1 to 3 cm, or it may have the form of an artificial (seaweed) reef, and in the latter case, it is preferable that it has a tetrapod shape or a regular tetrahedron shape.

[0019] According to the present invention, sewage sludge and an iron-containing substance are solidified into a permeable mass using a binder to form a solid material for seaweed bed formation.

[0020] Sewage sludge contains humic acids such as fulvic acid and humic acid, mineral components, and organic matter. However, when sewage sludge is carbonized while controlling the temperature, most of the organic matter in the sludge is eliminated, and sewage sludge charcoal is obtained in which humic acid and mineral components remain.

[0021] In other words, sewage sludge contains humic acid and mineral components, but does not contain organic matter that causes seawater pollution such as red tides.

[0022] Then, when the solid material for seaweed bed formation is placed on the seabed, the humic acid in the sewage sludge coal chelates and complexes with the iron in the iron-containing material inside the solid material into which seawater has seeped, producing iron humate, especially iron fulvic acid, and (divalent) iron ions and mineral components leach from the solid material into the surrounding seawater.

[0023] Moreover, there is no risk of organic matter, which causes seawater pollution such as red tides, leaching out from the solid material used to form seaweed beds.

[0024] Furthermore, since the sewage sludge and slag are solidified into a permeable mass using a binder, the leaching of iron ions and mineral components from the solid material for seaweed bed formation can be slowed down, thus enabling a stable supply of iron ions and mineral components to the water body over a long period of time.

[0025] Furthermore, the surface of the solid material used for seaweed bed formation develops irregularities throughout, which are suitable for the growth of seaweed (seagrass). Moreover, in this case, the shape of these irregularities can be easily changed according to the usage environment by changing the average particle size of the sewage sludge and iron-containing material, as well as the mixing ratio of the sewage sludge, iron-containing material, and binder.

[0026] This is a schematic cross-sectional view of a solid material for seaweed bed formation according to one embodiment of the present invention. This is a schematic diagram showing a solid material for seaweed bed formation according to another embodiment of the present invention. This is a schematic cross-sectional view of a solid material for seaweed bed formation according to yet another embodiment of the present invention.

[0027] The configuration of the present invention will be described below based on preferred embodiments with reference to the attached drawings. Figure 1 is a schematic cross-sectional view of a solid material for seaweed bed formation according to one embodiment of the present invention. Referring to Figure 1, the solid material 1 for seaweed bed formation of the present invention consists of sewage sludge char 2, large-particle steelmaking slag 3, small-particle steelmaking slag 4, and activated carbon 5 that has adsorbed fulvic acid, which are solidified into a water-permeable mass with a binder 6.

[0028] The average particle sizes of the sewage sludge 2, large-particle steelmaking slag 3, small-particle steelmaking slag 4, and activated carbon 5, as well as the mixing ratio of the sewage sludge 2, large-particle steelmaking slag 3, small-particle steelmaking slag 4, activated carbon 5, and cement 6, are determined according to the environment in which the solid material for seaweed bed formation 1 is used and are not particularly limited. However, in this embodiment, the solid material for seaweed bed formation 1 contains 15 to 20% by weight of sewage sludge 2 with a particle size of 0.5 to 1.5 mm, 5 to 10% by weight of (large-particle) steelmaking slag 3 with a particle size of 5 to 10 mm, 5 to 10% by weight of (small-particle) steelmaking slag 4 with a particle size of 0.5 to 1.5 mm, 5 to 10% by weight of activated carbon 5 with a particle size of 0.5 to 1.5 mm, and 30 to 50% by weight of cement 6.

[0029] In this embodiment, steelmaking slags 3 and 4 of different particle sizes are used, but it is also possible to use one type of steelmaking slag with the same particle size, or to use three or more types of steelmaking slag with different particle sizes.

[0030] Furthermore, although steelmaking slag 3 and 4 are used in this embodiment, other types of slag (blast furnace slag, ore slag, castings, etc.) can be used instead of or in addition to steelmaking slag 3 and 4.

[0031] It is preferable that the activated carbon 5 is formed by carbonizing and activating waste plastic or waste clothing.

[0032] In this embodiment, cement is used as the binder 6, but the binder 6 is not particularly limited as long as it can bind the sewage sludge 2, steelmaking slag 3, 4 and activated carbon 5 together to form a permeable mass.

[0033] The cement 6 is preferably made of blast furnace cement, permeable cement, or a combination thereof. This allows for smoother leaching of nutrients (iron, mineral components, etc.) from the solid material 1 for seaweed bed formation placed in the sea, and also creates an uneven surface on the surface of the solid material 1 that is more suitable for the growth of algae.

[0034] When combining blast furnace cement and permeable cement, the mixing ratio is determined according to the environment in which the solid material 1 for seaweed bed formation is used.

[0035] According to the present invention, sewage sludge char 2, steelmaking slag 3 and 4 of two different particle sizes, and activated carbon 5 that has adsorbed fulvic acid are solidified into a permeable mass 1 with cement 6 to form a solid material 1 for seaweed bed formation.

[0036] Sewage sludge contains humic acids such as fulvic acid and humic acid, mineral components (inorganic nitrogen, phosphorus, potassium, iron, silica, etc.), and organic matter. However, when sewage sludge is carbonized while controlling the temperature, most of the organic matter in the sewage sludge is eliminated, and sewage sludge charcoal is obtained in which humic acid and mineral components remain.

[0037] In other words, sewage sludge charcoal 2 contains humic acid and mineral components, but does not contain organic matter that causes seawater pollution such as red tides. In this example, sewage sludge charcoal formed by carbonizing sewage sludge at 300-400°C or below is used, and in this case, the fulvic acid content in the sewage sludge charcoal is 5-7%.

[0038] On the other hand, activated carbon formed by carbonizing and activating waste plastics or waste clothing is produced in 1,000 m³. ２ It has a large specific surface area of ​​approximately 1 / g, and furthermore, it has the characteristic of having a faster adsorption rate compared to existing activated carbons (coconut shell activated carbon, coal-based activated carbon, etc.), and therefore can efficiently adsorb a larger amount of fulvic acid.

[0039] In fact, when fulvic acid is adsorbed onto activated carbon formed from waste plastic or waste clothing, the average fulvic acid content of this activated carbon is about 20%, which is about four times the amount of fulvic acid found in sewage sludge charcoal 2.

[0040] The activated carbon 5, which has adsorbed fulvic acid, is used as needed when the supply of fulvic acid from the sewage sludge charcoal 2 is insufficient, and is not an essential component of the solid material 1 for seaweed bed formation according to the present invention.

[0041] Thus, when the seaweed bed-forming solid material 1 is placed on the seabed, the fulvic acid in the sewage sludge char 2 and activated carbon 5 chelates and complexes with the steelmaking slag 3 and 4 inside the seaweed bed-forming solid material 1 into which seawater has seeped, producing iron fulvic acid, and (divalent) iron ions and mineral components are leached from the seaweed bed-forming solid material 1 into the surrounding seawater.

[0042] Further, since the sewage sludge peat 2, steelmaking slags 3, 4, and activated carbon 5 are solidified into a lump with cement 6, the elution of iron ions and mineral components from the solid matter 1 for forming a kelp bed can be slowed down. Thus, the iron ions and mineral components can be stably supplied to the water area over a long period of time.

[0043] Further, since the sewage sludge peat 2, steelmaking slags 3, 4, and activated carbon 5 are solidified with cement 6, irregularities suitable for the settlement and propagation of seaweeds (sea grasses) are formed over the entire surface of the solid matter 1 for forming a kelp bed. Moreover, in this case, by changing the average particle size of each of the sewage sludge peat 2, steelmaking slags 3, 4, and activated carbon 5, and the mixing ratio of the sewage sludge peat 2, steelmaking slags 3, 4, activated carbon 5, and cement 6, this irregular shape can be easily changed according to the utilization environment.

[0044] Note that there is a risk of predation by herbivorous fish during the period from when seaweeds (sea grasses) start to settle on the solid matter 1 for forming a kelp bed until they grow to a certain size. To prevent this, it is preferable to dispose of the solid matter 1 for forming a kelp bed on the seabed in a state of being contained in a gunny sack.

[0045] The solid matter 1 for forming a kelp bed of the present invention only needs to be in a lump shape, and its shape and size are not limited. For example, as shown in FIG. 2(C), the solid matter 1' for forming a kelp bed may have a form of gravel (a collection of a large number of amorphous lumps) with an average particle size of 1 to 3 cm. In this case, the solid matter 1' for forming a kelp bed is scattered on the seabed. Thereby, the uplift of mud by the ocean current is prevented, mud does not adhere to the seaweeds (sea grasses), the photosynthesis of the seaweeds (sea grasses) is not inhibited, and moreover, the iron and mineral components necessary for the growth of the seaweeds (sea grasses) are also supplied.

[0046] Further, for example, as shown in FIG. 2(A), the solid matter 1' for forming a kelp bed may have a form of a regular tetrahedron artificial fishing (algae) reef, or as shown in FIG. 2(B), it may have a form of a tetrapod. Alternatively, the solid matter 1'' for forming a kelp bed may have a form of the base part of an offshore wind power generation device.

[0047] In the case of the embodiment shown in Fig. 2(A), since the solid matter 1' for seaweed bed formation has a regular tetrahedron shape, it is difficult to be washed away by the tidal current. Further, even if it is moved (rolled) by the tidal current, its surface maintains an inclined state, so that floating mud in the sea is unlikely to accumulate on the surface. As a result, the growth of seaweeds (sea grasses) fixed to the solid matter 1' for seaweed bed formation is prevented from being hindered by the influence of the mud on the seabed.

[0048] Fig. 3 is a schematic cross-sectional view of a solid matter for seaweed bed formation according to yet another embodiment of the present invention. In the embodiment of Fig. 3, in the embodiment shown in Fig. 1, in order to prevent the solid matter for seaweed bed formation from being slightly insufficient in strength with respect to the usage environment and collapsing in a short period depending on the mixing ratio of its forming materials, the structural strength of the solid matter for seaweed bed formation is enhanced. Therefore, in Fig. 3, the same components as those shown in Fig. 1 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0049] Referring to Fig. 3, in this embodiment, the solid matter 7 for seaweed bed formation includes a reinforcing member 8 made of carbon fiber. The carbon fiber is preferably recycled carbon fiber. The reinforcing member 8 may be, for example, a plurality of carbon fibers themselves as shown in Fig. 3(A), or may be a plurality of carbon fibers solidified in a rod shape as shown in Fig. 3(B), or may be a plurality of carbon fibers solidified in a plate shape as shown in Fig. 3(C).

[0050] As can be seen from Fig. 3(C), when the reinforcing member 8 is composed of a plurality of carbon fibers solidified in a plate shape, it is preferable that a plurality of holes 8a penetrating both surfaces thereof are provided in the plate body. Thereby, the portion 7a located on one surface side of the reinforcing member 8 in the solid matter 7 for seaweed bed formation and the portion 7b located on the other surface side of the reinforcing member 8 are firmly joined through the holes 8a, and the reinforcing member 8 and the other forming materials of the solid matter for seaweed bed formation are integrated.

[0051] Carbon fiber has the characteristics of not shrinking due to heat and being strong against tension, compression and bending. By integrating this with the other forming materials of the solid matter for seaweed bed formation, the strength of the solid matter for seaweed bed formation increases.

[0052] Although preferred embodiments of the present invention have been described above, it goes without saying that the configuration of the present invention is not limited to the above-described embodiments, and that those skilled in the art can devise various modifications within the scope of the configuration described in the appended claims.

[0053] For example, although slag is used in the embodiment shown in Figure 1, the present invention is not limited to slag, and any iron-containing material can be used. Preferably, the iron-containing material consists of one or more of the following: iron powder, iron oxide powder (e.g., red iron oxide), and slag.

[0054] Furthermore, in the embodiment shown in Figure 1, the solid material 1 for seaweed bed formation may also contain polyglutamic acid. In this case, polyglutamic acid, like fulvic acid, becomes a stable source of iron ions by chelating and complexing iron in seawater.

[0055] Furthermore, for example, in the embodiment shown in Figure 1, the solid material 1 for seaweed bed formation may further include a carbonizing agent, or carbonized waste plastic, or carbonized waste clothing, or powder of carbonized seashells and / or crustaceans, or dried sewage sludge, or a combination of two or more of these. In this case, the average particle size of each of these additional materials and their weight ratio to the solid material 1 for seaweed bed formation are determined according to the environment in which the solid material 1 for seaweed bed formation is used.

[0056] Dried sewage sludge contains more humic acid and mineral components than sewage sludge charcoal 2, but it also contains organic matter that can cause seawater pollution. Therefore, dried sewage sludge is used as a supplement when the supply of humic acid, especially fulvic acid, is insufficient with sewage sludge charcoal 2 and activated carbon 5 alone.

[0057] Furthermore, as a reinforcing member, FRP carbonized material (mainly composed of glass), obtained by carbonizing discarded FRP fishing boats, etc., can be added to the solid material 1 for seaweed bed formation, either together with or in place of carbon fibers.

[0058] Although the above description has focused on the application of the present invention in seawater, the present invention is also applicable in freshwater. Therefore, the same effects as in seawater can be obtained by placing the solid material for seaweed bed formation of the present invention in rivers, lakes, etc.

[0059] 1, 1', 1" Solid material for seaweed bed formation 2 Sewage sludge charcoal 3 Large particle size steelmaking slag 4 Small particle size steelmaking slag 5 Activated carbon with fulvic acid adsorbed 6 Binder (cement) 7 Solid material for seaweed bed formation 7a Part located on one side of the reinforcing member 7b Part located on the other side of the reinforcing member 8 Reinforcing member 8a Hole

Claims

1. A solid material for forming seaweed beds, characterized by being made of carbonized sewage sludge and iron-containing material solidified into a permeable mass by a binder.

2. The solid material for forming seaweed beds according to claim 1, characterized in that the iron-containing substance is one or more of the following: iron powder, iron oxide powder, and slag.

3. The solid material for forming seaweed beds according to claim 2, characterized in that it contains polyglutamic acid.

4. The solid material for forming seaweed beds according to claim 2, characterized in that it contains activated carbon on which fulvic acid has been adsorbed.

5. The solid material for seaweed bed formation according to claim 4, characterized in that the activated carbon is formed by carbonizing and activating waste plastic or waste clothing.

6. The solid material for forming seaweed beds according to claim 2, characterized in that it includes a reinforcing member made of carbon fiber and / or FRP carbonized material.

7. The solid material for forming seaweed beds according to claim 2, characterized in that it contains a carbonizing agent.

8. The solid material for forming seaweed beds according to claim 7, characterized in that it contains carbonized waste plastic or carbonized waste clothing.

9. The solid material for forming seaweed beds according to claim 8, characterized in that it contains powder of seashells and / or carbonized crustaceans.

10. The solid material for forming seaweed beds according to claim 9, characterized in that it contains dried sewage sludge.

11. The solid material for forming seaweed beds according to claim 2, characterized in that the slag consists of large-grain steelmaking slag and small-grain steelmaking slag.

12. The solid material for forming seaweed beds according to claim 1, characterized in that the binder is cement.

13. The solid material for forming seaweed beds according to claim 12, characterized in that the cement is blast furnace cement and / or permeable cement.

14. A solid material for forming seaweed beds according to any one of claims 1 to 13, characterized in that it has the form of a tetrapod or regular tetrahedron artificial reef.

15. A solid material for forming seaweed beds according to any one of claims 1 to 13, characterized in that it has the form of gravel with an average particle size of 1 to 3 cm.

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