Equipment for raising aquatic organisms, salt composition for the equipment, salt water or brackish water, use of the salt composition, method for producing salt water or brackish water and use thereof, and method for raising aquatic organisms

Abstract

The present invention relates to an installation for breeding aquatic organisms, in particular fish or crustaceans, having a breeding tank containing salt water or brackish water, the salt water or brackish water being producible or produced by a salt composition, the salt composition containing 70 mol% to 99.9 mol% sodium chloride (NaCl) and 0.1 mol% to 30 mol% magnesium chloride (MgCl2), respectively, based on the total amount of substance of the salt composition. Preferably, the salt composition is sulfate-free or at least sulfate-poor. The present invention further relates to a salt composition for producing brackish water or salt water for said installation, brackish water or salt water, a method for producing brackish water or salt water, as well as aquatic organisms raised in said installation.

Description

[Technical Field]

[0001] The present invention relates to a facility for raising aquatic organisms, particularly fish or crustaceans, having a breeding tank containing saltwater or brackish water, where the saltwater or brackish water can be produced or has been produced using a salt composition, and the salt composition contains 70 mol% to 99.9 mol% sodium chloride (NaCl) and 0.1 mol% to 30 mol% magnesium chloride (MgCl), based on the total amount of substances in the salt composition. The present invention also relates to a salt composition for producing brackish water or salt water for the facility, brackish water or salt water, a method for producing brackish water or salt water, and aquatic organisms raised in the facility.

[0002] CN Patent No. 1321913 describes a salt composition, for example as an additive to artificial seawater for fish farming, as well as a method for producing the salt composition. CN Patent No. 1321913 discloses a salt composition with low sulfate content. In contrast, it does not disclose a sulfate-free composition.

[0003] JP 2006-006150 A discloses a salt composition that can be used for raising shrimp. Paragraph

[0017] discloses a composition containing 85 mol% NaCl, 6.5 mol% MgCl2, 3.2 mol% MgSO4, and 1.9 mol% CaSO4. Thus, while a salt composition with a low sulfate content is disclosed, a sulfate-free salt composition is not disclosed.

[0004] Aquaculture for raising aquatic organisms such as fish, shellfish, or crustaceans has been known for some time. In this conventional aquaculture, existing bodies of water, usually isolated ponds, channels, tanks, or net cages, are used, in which the organisms are grown until they are ready for harvest. In particular in coastal areas, existing saltwater or brackish water can be used, so net cages are often used for raising the organisms.

[0005] A well-known form of aquaculture is inland aquaculture using rearing tanks, known as recirculating systems. To produce the brine used for this (e.g., artificial seawater in rearing tanks where aquatic organisms are reared until harvest), sea salts obtained from seawater are usually dissolved in tap water, groundwater, or surface water to create a typical habitat for the aquaculture organisms. This artificial seawater usually contains a large amount of sulfate.

[0006] In aquaculture facilities in rivers or narrow bays, the culture water is typically not purified by removing waste and feed residues. Instead, water is exchanged by passing it through the rearing cages. In contrast, circulation systems require several stages of filters to purify the water in the rearing tanks. Despite continuous filtration and water circulation, a 1-4 mm thick layer of aquatic organism feed residues and waste (known as sediment) forms locally at the bottom of the rearing tank, for example, in corners or in the water filtration device. Microorganisms grow within this sediment. Oxygen is consumed directly in the microbial decomposition process, so it can only penetrate the sediment to a depth of a few micrometers. The penetration depth depends on various parameters but is typically 20-100 μm.

[0007] The inventors discovered that microorganisms living in sediments utilize sulfate instead of oxygen as an electron acceptor for metabolism, resulting in the formation of hydrogen sulfide (H2S), which is released into the water of the aquarium. This can lead to localized H2S concentrations in the sediment area that are lethal to aquatic organisms. These lethal H2S concentrations can lead to harvest cessation, i.e., the death of aquatic organisms, even if they only remain in the area for a short time. All fish species raised in aquaculture, especially Atlantic salmon (Salmo salar), yellowtail kingfish (Seriola lalandi), and rainbow trout (Onchorrynchis mykiss), are particularly sensitive to hydrogen sulfide. Among crustaceans, the white-spotted shrimp (Litopenaeus vannamei) and the Japanese black prawn (Panaeus monodon) are particularly susceptible.

[0008] The inventors have further discovered that this problem is solved by using sulfate-free brackish or salt water, which is not dangerous to aquatic life up to a certain sulfate concentration, i.e., only amounts of H2S that are harmless to aquatic life are formed in the sediment.

[0009] At the same time, the salt composition provides a method for producing brackish or salty water in which aquatic organisms can grow particularly well and which can provide a sufficient supply of all ions required for rearing, thereby ensuring that the growth rate required for economical rearing can be achieved.

[0010] The object of the present invention is to provide an installation with brackish or salt water for rearing aquatic organisms as mentioned at the outset, in which no hydrogen sulfide is released into the rearing tank of the installation, or only in amounts that are harmless to the aquatic organisms.

[0011] According to the present invention, the above problem is solved in that the salt composition is sulfate-free or at least sulfate-poor.

[0012] A sulfate-free salt composition does not contain any sulfate at all, whereas a low-sulfate salt composition contains up to 5 mol % of sulfate, preferably up to 5 mol % of the sulfate, based on the total amount of substance of the salt composition, consisting of magnesium sulfate. It is also conceivable that the sulfate comes from a solution of sodium sulfate and / or potassium sulfate. Furthermore, it is also conceivable to use a mixture of different sulfates.

[0013] Advantageously, ions necessary for particularly good growth of aquatic organisms are present in sufficient amounts in brackish or salt water produced with the salt composition according to the invention.

[0014] Sulfate-free or low-sulfate salt compositions are obtained, in particular, by using chloride salts, such as magnesium chloride, as a substitute for sulfate salts, such as magnesium sulfate. In the salt compositions according to the invention, sulfate salts are always replaced by chloride salts. Advantageously, this substitution allows the ionic ratio, in particular the cation ratio, for example the magnesium to calcium ratio or the magnesium to potassium ratio, of the artificial salt water or brackish water produced to be advantageously comparable to the ionic ratio of the water in the natural habitat of aquatic organisms.

[0015] It is believed that sodium chloride can be used as an alternative to sodium sulfate.

[0016] Brackish or salt water according to the present invention is sulfate-free or at least sulfate-low, depending on the salt composition used in its production.

[0017] The salt composition preferably contains potassium chloride (KCl), preferably less than 5 mol %, in particular 0.5 mol % to 4.0 mol %, particularly preferably 1.5 mol % to 2.25 mol %, of potassium chloride relative to the total amount of substances in the salt composition.

[0018] In one embodiment of the present invention, the salt composition contains calcium chloride (CaCl), preferably less than 5 mol %, particularly 0.5 mol % to 4 mol %, and particularly preferably 1.50 mol % to 2.25 mol %, of calcium chloride based on the total amount of substances in the salt composition. Calcium ions and chloride ions are essential for the growth of aquatic organisms. Because calcium chloride dissolves particularly well in water, the aquarium can be used for breeding more quickly than when other calcium sources are used. This reduces downtime and improves productivity.

[0019] The inventors have discovered that for sulfate-free or sulfate-low salt compositions, sulfate can be replaced by chloride salts, and that the ion ratios required for rearing aquatic organisms in rearing facilities operated with salt water or brackish water according to the present invention, such as the ion ratio of magnesium ions to calcium ions or the ion ratio of magnesium ions to potassium ions, preferably correspond to or at least closely resemble the ion ratios of the water in the natural habitat of the aquatic organisms.

[0020] In another embodiment of the present invention, the salt composition contains sodium carbonate (NaCO), preferably in an amount of 0.5 mol % or less, particularly 0.01 mol % to 0.15 mol %, and particularly preferably 0.065 mol %, based on the total amount of substances in the salt composition. Sodium carbonate has a much higher solubility in water than sodium bicarbonate, which is conventionally known as a carbonate supply agent for producing saltwater or brackish water for breeding facilities. This higher solubility allows the breeding facility to be used for breeding additional aquatic organisms more quickly after replacing the saltwater or brackish water used to operate the breeding facility, thereby reducing downtime.

[0021] Preferably, the salt composition contains sodium bicarbonate (NaHCO), preferably in an amount of 0.5 mol% or less, particularly 0.35 mol% or less, and particularly preferably 0.20 mol% to 0.31 mol% of sodium bicarbonate, based on the total amount of substances in the salt composition. Sodium bicarbonate is also called sodium hydrogen carbonate. Sodium bicarbonate is less soluble in water than sodium carbonate, but is much easier to store. Sodium carbonate is highly hygroscopic and must be stored sealed or in a dry atmosphere, whereas sodium bicarbonate can be stored, for example, in a breathable bag without substantially changing its properties. This is advantageous when the transportation route to the breeding facility is long or when the storage period in the breeding facility is long, eliminating the need for scheduled delivery. Sodium bicarbonate can also be used to produce salt compositions that require very precise adjustment of the pH value of brine or brackish water used in the operation of the breeding facility according to the present invention and produced from the salt composition.

[0022] A low-sulfate salt composition is, for example, a salt composition containing 5 mol% or less of sulfate (SO4 2- ) is contained. Suitable sulfates include, for example, sulfates selected from the group consisting of sodium sulfate, magnesium sulfate, potassium sulfate, and calcium sulfate, and more preferably sulfates selected from the group consisting of sodium sulfate and magnesium sulfate. In one embodiment, the low-sulfate salt composition contains 5 mol% or less of sodium sulfate (Na2SO4), and in another embodiment, the low-sulfate salt composition contains 5 mol% or less of magnesium sulfate (MgSO4), each content being relative to the total amount of substance of the salt composition.

[0023] The inventors have discovered that in a low-sulfate salt composition, sodium sulfate can be replaced with magnesium sulfate without adversely affecting the growth of aquatic organisms. Because sodium sulfate is more expensive than magnesium sulfate, this salt composition can advantageously be provided at a particularly low cost. The breeding facility according to the present invention can be operated particularly economically. For a low-sulfate salt composition, a magnesium sulfate content of 4.28 mol % relative to the total amount of material in the salt composition has been found to be advantageous. This allows optimal harvesting results to be achieved, i.e., rapid growth can be achieved with a low rate of loss of aquatic organisms due to mortality before harvesting can begin.

[0024] In one embodiment of the present invention, the sulfate-free salt composition contains 7.5 mol% to 12 mol%, preferably 9.0 mol% to 10.0 mol%, of magnesium chloride (MgCl2) relative to the total amount of substances in the salt composition. This ratio has proven particularly advantageous for achieving optimal magnesium-to-calcium and magnesium-to-potassium ion ratios for the metabolism of aquatic organisms in the brackish or salt water of the rearing facility. These ion ratios are highly relevant for optimal growth of aquatic organisms. Advantageously, a particularly efficient rearing facility can be provided.

[0025] In a further embodiment of the invention, the low-sulfate salt composition contains 4.0 mol % to 7.0 mol %, preferably 5.0 mol % to 6.0 mol % magnesium chloride (MgCl2) based on the total amount of substance of the salt composition, which has proven to be particularly advantageous for achieving optimal magnesium to calcium and magnesium to potassium cation ratios for the metabolism of aquatic organisms in brackish or salt water of aquariums.

[0026] In one embodiment of the invention, the salt composition is free of magnesium sulfate or low in magnesium sulfate. Advantageously, compared to salt compositions for producing artificial brines, the salt composition contains no sulfates at all or only a small proportion by introducing magnesium sulfate. The salt composition according to the invention is synthetic and cannot be produced by drying seawater.

[0027] Preferably, the low-sulfate or sulfate-free salt composition according to the present invention for producing brackish or salt water for aquatic organism breeding, particularly for fish or crustacean breeding, contains 70 mol% to 99.9 mol% sodium chloride (NaCl) and 0.1 mol% to 30 mol% magnesium chloride (MgCl), based on the total amount of substances in the salt composition. It goes without saying that the mol% of salt contained in the salt composition refers to the mol% before the brackish or salt water is produced. It is also clear to those skilled in the art that the mol% may change during the production of the brackish or salt water.

[0028] The salinity of the brackish water or salt water according to the present invention, which can be produced or is produced using the salt composition according to the present invention, is 0.10% to 5.0%, preferably 2.5% to 3.5%. Salinities up to 2.5% to 3.5% are particularly suitable for raising aquatic animals. In describing the salinity, percentages refer to the mass proportion of salt in the water. For example, a salinity of 1.0% means that 10 g of salt is added to 1 kg of water to produce brine.

[0029] Brackish water has a salinity of 0.1% to 1.0%, while salt water has a salinity of 1.0% or more. Seawater is considered to have a salinity of 3.0% to 3.5%.

[0030] In the method according to the invention for producing brackish or salt water for a facility for rearing aquatic organisms, with the required salinity for rearing, a salt composition is introduced into fresh water, for example from a lake, in particular tap water, groundwater or surface water, the ion proportion of which is negligible compared to the ion proportion that the brackish or salt water according to the invention should have.

[0031] The aquatic organisms of the present invention reared in the rearing facilities of the present invention differ from previously known aquatic organisms in that it is possible to determine whether the aquatic organisms have been reared in sulfate-free or sulfate-low salt or brackish water based on the renal activity of the aquatic organisms. Detectable sulfates in aquatic organisms are formed, for example, by hepatic metabolism of amino acid-containing feed or by ingestion from the salt or brackish water in which the aquatic organisms are reared.

[0032] That is, the inventors have been able to demonstrate that aquatic organisms reared in a rearing facility according to the present invention, whose natural habitat is saltwater and which is operated with low-sulfate or sulfate-free saltwater, exhibit lower renal activity than comparable aquatic organisms reared in their natural habitat.

[0033] By examining the kidneys of the carcasses of aquatic organisms according to the present invention, it is possible to determine whether they have been reared in low-sulfate or sulfate-free salt or brackish water.

[0034] Low-sulfate water and sulfate-free water are understood to be salt or brackish water used in the operation of farm facilities and produced using low-sulfate or sulfate-free salt compositions.

[0035] Previously known salt compositions for producing artificial seawater for the operation of aquaculture facilities have the substance amount ratios shown in Table 1 below relative to the total substance amount of the salt composition:

[0036] [Table 1]

[0037] In rearing facilities, brackish or salt water produced with this composition (7 mol% magnesium sulfate) carries a high risk of yield loss of up to 2% due to the formation of hydrogen sulfide in the sediment zone.

[0038] In the following, the invention will be explained in more detail on the basis of several examples.

[0039] Example 1: A low sulfate salt composition according to the present invention has the composition shown in Table 2.1 below:

[0040] [Table 2.1]

[0041] Brine with a salinity of 3.0%, produced using the salt composition shown in Table 2.1, has the ion concentrations shown in Table 2.2 below:

[0042] [Table 2.2]

[0043] Example 2: A sulfate-free salt composition according to the present invention has the composition shown in Table 3.1 below:

[0044] [Table 3.1]

[0045] Since a specific percentage of magnesium is required for aquatic life, the absence of magnesium sulfate is compensated for by increasing the percentage of magnesium chloride, i.e., magnesium sulfate is replaced by magnesium chloride.

[0046] The composition according to Example 2 can be used to produce brackish or salt water for aquariums, and the aquatic organisms in the aquarium will have similar growth curves to those grown in brackish or salt water produced by the composition according to Example 1, with little or no harvest loss (less than 0.5%) due to hydrogen sulfide leaching from the sediment. Brine with a salinity of 3.0% produced using the salt composition shown in Table 3.1 has the ion concentrations shown in Table 3.2 below:

[0047] [Table 3.2]

[0048] Example 3: Another sulfate-free salt composition according to the present invention has the composition shown in Table 4.1 below:

[0049] [Table 4.1]

[0050] The composition according to Example 3 can produce brackish or salt water for aquariums, and the aquatic organisms in the aquarium exhibit growth curves similar to those in the brackish or salt water produced by the composition according to Examples 1 or 2, with almost no harvest loss (less than 0.5%) due to hydrogen sulfide leaching from the sediment. The composition according to Example 3 has the advantage that the high solubility of sodium carbonate and the absence of sodium bicarbonate can reduce the downtime of the aquarium by several hours during water changes.

[0051] Brine having a salinity of 3.0% produced using the salt composition shown in Table 4.1 has the ion concentrations shown in Table 4.2 below:

[0052] [Table 4.2]

[0053] It is understood that the invention is not limited to these examples. In particular, it is conceivable that brackish or salt water according to the invention has a salinity different from the salinities mentioned above, for example 0.75% or 3.5%.

[0054] It is further contemplated that sulfates other than magnesium sulfate, such as sodium sulfate or potassium sulfate, may be used to produce low-sulfate brine or brackish water.

Claims

1. A facility for raising aquatic organisms, comprising a breeding tank containing saltwater or brackish water, The salt water or brackish water can be produced or has been produced by a salt composition, and the salt composition contains, relative to the total amount of substances of the salt composition, 70 mol % to 99.9 mol % of sodium chloride (NaCl), 0.1 mol % to 30 mol % of magnesium chloride (MgCl ２ ) and 0.5 mol % or less of sodium bicarbonate (NaHCO 3 ), The salt composition is sulfate-free or contains 5 mol % or less of sulfate.

2. The breeding facility according to claim 1, characterized in that the salt composition contains less than 5 mol% potassium chloride (KCl) relative to the total amount of substance of the salt composition.

3. The salt composition contains less than 5 mol% calcium chloride (CaCl) based on the total amount of material of the salt composition. ２ 2. The breeding facility according to claim 1, further comprising:

4. The salt composition contains 0.5 mol % or less of sodium carbonate (Na ２ CO ３ 2. The breeding facility according to claim 1, further comprising:

5. The sulfate-containing salt composition contains less than 5 mol% of magnesium sulfate (MgSO ) based on the total amount of substance of the salt composition. ４ 2. The breeding facility according to claim 1, further comprising:

6. The sulfate-free salt composition contains 7.5 mol % to 12 mol % magnesium chloride (MgCl ２ 2. The breeding facility according to claim 1, further comprising:

7. The salt composition containing the sulfate contains 4.0 mol % to 7.0 mol % of magnesium chloride (MgCl ２ 2. The breeding facility according to claim 1, further comprising:

8. A salt composition for producing salt water or brackish water for a facility for raising aquatic organisms, comprising: The salt composition contains 70 mol% to 99.9 mol% sodium chloride (NaCl), 0.1 mol% to 30 mol% magnesium chloride (MgCl ２ ) and 0.5 mol % or less of sodium bicarbonate (NaHCO 3 ), The salt composition is characterized in that it contains no sulfate or 5 mol % or less of sulfate.

9. Salt or brackish water for a facility for raising aquatic organisms, which can be produced or has been produced by the salt composition of claim 8.

10. The brackish water or salt water according to claim 9, wherein the salinity of the brackish water or salt water is 0.10% to 5%.

11. 8. The method for producing brackish or salt water for a facility for raising aquatic organisms according to any one of claims 1 to 7, 9. A method comprising introducing the salt composition of claim 8 into freshwater and adjusting the salinity to 1.0% to 5.0%.

12. A method for raising aquatic organisms in a facility for raising aquatic organisms according to any one of claims 1 to 7, which comprises brackish water or salt water having a salinity of 0.1% to 5.0% that can be produced or that is produced using the salt composition according to claim 8.

13. 9. Use of the salt composition according to claim 8 for operating a facility for raising said aquatic organisms.

14. Use of the brackish or salt water according to claim 9 or 10 for operating an installation for rearing said aquatic organisms.

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