Equipment for raising aquatic organisms, salt composition for the equipment, salt water or brackish water

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 an apparatus for breeding aquatic organisms, particularly fish or crustaceans, having a breeding tank containing salt water or brackish water, wherein the salt water or brackish water can be produced or has been produced by a salt composition, and the salt composition contains 70 mol % to 99.9 mol % of sodium chloride (NaCl) and 0.1 mol % to 30 mol % of magnesium chloride (MgCl) relative to the total substance amount of the salt composition. 2 The present invention further relates to a salt composition for producing brackish or salt water for said facility, to the brackish or salt water, to a method for producing brackish or salt water, and to aquatic organisms kept in said facility.

[0002] CN Patent 1321913 describes a salt composition, e.g. as an artificial seawater additive for fish farming, as well as a method for producing the salt composition. CN Patent 1321913 discloses a salt composition with low sulfate content. In contrast, no sulfate-free composition is disclosed.

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

[0017] states that the salt composition contains 85 mol% NaCl, 6.5 mol% MgCl 2 , 3.2 mol% MgSO 4 and 1.9 mol% CaSO 4 Thus, although low sulfate salt compositions are disclosed, sulfate-free salt compositions are not disclosed.

[0004] Aquaculture for the rearing of aquatic organisms such as fish, shellfish or crustaceans is known from the past. In this conventional aquaculture, existing bodies of water are used, usually separate ponds, channels, tanks or net cages, in which the organisms are grown until the so-called harvest. Especially in coastal areas, the rearing is often carried out in net cages, since existing salt or brackish water can be used.

[0005] A known form of aquaculture is inland aquaculture using breeding tanks, so-called recirculating facilities. To produce the saltwater used for this (e.g. artificial seawater in breeding tanks where aquatic organisms are kept until harvest), sea salts obtained from seawater are usually dissolved in tap water, groundwater or surface water to create a typical habitat for the organisms to be cultivated. This artificial seawater usually contains a large amount of sulfates.

[0006] In aquaculture facilities in rivers or narrow bays, the culture water is not usually purified by removing waste and feed residues, but water is exchanged by passing it through the breeding cages, whereas in circulation facilities several stages of filters are required to purify the water in the breeding tanks. Despite the permanent filtration and water circulation, a layer of 1 mm to 4 mm thick consisting of feed residues and excreta of aquatic organisms, a so-called sediment, is formed locally at the bottom of the breeding tank, for example in corners or in the water filtration device, and microorganisms grow in this sediment. Oxygen is consumed directly in the microbial decomposition process and can therefore only penetrate into the sediment to a depth of a few μm. The penetration depth depends on various parameters but is generally between 20 μm and 100 μm.

[0007] The inventors believe that microorganisms living in the sediment utilize sulfate instead of oxygen as an electron acceptor for their metabolism, thereby producing hydrogen sulfide (H 2 They found that the formation of H2S, which is lethal to aquatic organisms, occurs locally in the sediment area and is released into the water of the aquarium. 2 S concentrations, which can lead to this lethal H 2S concentrations can lead to the cessation of harvest, 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 are particularly sensitive to hydrogen sulfide, especially Atlantic salmon (Salmo salar), yellowtail kingfish (Seriola lalandi) and rainbow trout (Onchorrynchis mykiss). Among crustaceans, the white-spotted shrimp (Litopenaeus vannamei) and the black prawn (Panaeus monodon) are particularly affected.

[0008] The inventor further discovered that this problem is solved by sulfate-free brackish or salt water, which is not dangerous to aquatic life up to a certain sulfate concentration, i.e., a quantity of H that is harmless to aquatic life. 2 It was found that only S was formed in the precipitate.

[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 provides a sufficient supply of all ions required for rearing, thereby ensuring that the growth rates 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 beginning, 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 problem is solved in that the salt composition is sulfate-free or at least sulfate-low.

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

[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 replacement allows the ion ratios, in particular the cation ratios, such as 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 ion ratios of the water in the natural habitat of the aquatic organisms.

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

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

[0017] Suitably, the salt composition contains potassium chloride (KCl), preferably less than 5 mol %, in particular 0.5 mol % to 4.0 mol %, particularly suitably 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 invention, the salt composition comprises calcium chloride (CaCl 2 ), preferably less than 5 mol %, in particular 0.5 mol % to 4 mol %, particularly preferably 1.50 mol % to 2.25 mol % of calcium chloride relative to the total substance amount of the salt composition. Calcium ions and chloride ions are essential for the growth of aquatic organisms. Calcium chloride dissolves particularly well in water, so that the breeding tank can be used for breeding more quickly than when other calcium sources are used. This reduces downtime, thereby improving productivity.

[0019] The inventors have discovered that for sulfate-free or low-sulfate salt compositions, sulfates can be replaced by chloride salts, with the ion ratios required for rearing aquatic organisms in rearing facilities operated with salt or brackish water according to the invention, such as the ion ratio of magnesium ions to calcium ions or the ion ratio of magnesium ions to potassium ions, preferably corresponding to or at least very similar to 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 comprises sodium carbonate (Na 2 CO 3 ), preferably containing not more than 0.5 mol %, in particular 0.01 mol % to 0.15 mol %, particularly preferably 0.065 mol % sodium carbonate relative to the total amount of substances of the salt composition. Sodium carbonate is much more soluble in water than sodium bicarbonate, which is conventionally known as a carbonate supplying agent for producing salt water or brackish water for breeding facilities. The higher solubility allows the breeding facility to be used sooner for further breeding of aquatic organisms after replacing the salt water or brackish water used to operate the breeding facility, i.e. the downtime is reduced.

[0021] Preferably, the salt composition comprises sodium bicarbonate (NaHCO 3), preferably not more than 0.5 mol %, in particular not more than 0.35 mol %, particularly preferably 0.20 mol % to 0.31 mol % of sodium bicarbonate relative to the total amount of substance of 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 breathable bags without substantially changing its properties. This is advantageous in the case of long transport routes to the breeding facility or long storage periods in the breeding facility, where regular delivery is not necessary. Sodium bicarbonate can also be used for the production of salt compositions that require very precise adjustment of the pH value of the salt water or brackish water used in the operation of the breeding facility according to the invention and produced from the salt composition.

[0022] A low-sulfate salt composition is, for example, a salt composition having 5 mol % or less of sulfate (SO 4 2- ) is preferably selected from the group consisting of sodium sulfate, magnesium sulfate, potassium sulfate, and calcium sulfate, and more preferably 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 (Na 2 SO 4 ), and in other embodiments, the low-sulfate salt composition contains 5 mol % or less of magnesium sulfate (MgSO 4 ) and the content of each is based on the total amount of material of the salt composition.

[0023] The inventors have found that in a salt composition low in sulfate, sodium sulfate can be replaced by magnesium sulfate without adversely affecting the growth of the aquatic organisms. Advantageously, the salt composition can be provided at a particularly low price, since sodium sulfate is more expensive than magnesium sulfate. The breeding facility according to the invention can be operated particularly economically. In a salt composition low in sulfate, 4.28 mol % of magnesium sulfate, relative to the total amount of substance of the salt composition, has proven to be advantageous. This allows optimal harvesting results to be achieved, i.e. a low rate of loss due to death of the aquatic organisms before the start of the harvest and a rapid growth can be achieved.

[0024] In one embodiment of the invention, the sulfate-free salt composition contains 7.5 mol % to 12 mol %, preferably 9.0 mol % to 10.0 mol %, of magnesium chloride (MgCl 2 ) which has proven to be particularly advantageous for achieving an optimal magnesium to calcium ion ratio and an optimal magnesium to potassium ion ratio for the metabolism of aquatic organisms in the brackish or salt water of the rearing facility. These aforementioned 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 sulfate-poor salt composition comprises 4.0 mol % to 7.0 mol %, preferably 5.0 mol % to 6.0 mol % of magnesium chloride (MgCl 2 ) which has proven to be particularly advantageous for achieving an optimal magnesium to calcium and magnesium to potassium cation ratio for the metabolism of aquatic organisms in the brackish or salt water of the aquarium.

[0026] In one embodiment of the invention, the salt composition is free of magnesium sulfate or low in magnesium sulfate. Advantageously, it contains no sulfate salts at all or only a small proportion by introducing magnesium sulfate compared to salt compositions for producing artificial salt water. 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 invention for producing brackish or salt water for installations for the rearing of aquatic organisms, in particular for the rearing of fish or crustaceans, comprises 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. 2 ) are contained in the salt composition. It goes without saying that the mol% of the salt contained in the salt composition means the mol% before the brackish water or salt water is produced. In addition, it is clear to a person skilled in the art that the mol% may change during the production of the brackish water or salt water.

[0028] The salinity of the brackish or salt water according to the invention, which can be produced or is produced using the salt composition according to the 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 rearing aquatic animals. In the description of the salinity, the 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 the salt water.

[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 an installation 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, ground water 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 exhibit.

[0031] The aquatic organisms according to the invention reared in the rearing facility according to the invention differ from previously known aquatic organisms in that it is possible to ascertain based on the renal activity of the organism whether it has been reared in sulfate-free or sulfate-poor salt or brackish water. Detectable sulfates in the aquatic organisms are formed, for example, by hepatic metabolism of amino acid-containing feed or by uptake from the salt or brackish water in which the organism is 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 a natural habitat.

[0033] By examining the kidneys of the carcasses of aquatic organisms according to the present invention, it is possible to ascertain 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 the farm facility and produced using a low-sulfate or sulfate-free salt composition.

[0035] Previously known salt compositions for producing artificial seawater for the operation of aquaculture installations 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 brackish or salt water of rearing facilities produced with this composition (7 mol% magnesium sulfate), there is a high risk of yield losses 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 having 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 allows the production of brackish or salt water for a breeding facility, the aquatic organisms of which exhibit similar growth curves as those reared in brackish or salt water produced by the composition according to Example 1, and with almost no harvest loss (less than 0.5%) due to so-called hydrogen sulfide runoff from sediment. The salt water 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 allows the production of brackish or salt water for a breeding facility, the aquatic organisms of which exhibit a growth curve similar to that of the organisms reared in brackish or salt water produced by the composition according to Example 1 or 2, and the harvest loss due to hydrogen sulfide escaping from the so-called sediment is almost nonexistent (less than 0.5%). The composition according to Example 3 has the advantage that the high solubility of sodium carbonate and the absence of sodium bicarbonate allow the breeding facility to reduce the downtime for water exchange by several hours.

[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 salt or brackish water that is low in sulfate.

Claims

1. An installation for rearing aquatic organisms, in particular fish or crustaceans, comprising a rearing tank containing salt water or brackish water, The salt water or brackish water can be produced or has been produced by a salt composition, the salt composition comprising, relative to the total amount of substances of the salt composition, 70 mol % to 99.9 mol % of sodium chloride (NaCl) and 0.1 mol % to 30 mol % of magnesium chloride (MgCl ２ ) The salt composition is sulfate-free or at least sulfate-low.

2. The breeding facility according to claim 1, characterized in that the salt composition 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 based on the total amount of substances of the salt composition.

3. The salt composition comprises calcium chloride (CaCl ２ 3. The breeding facility according to claim 1 or 2, characterized in that it contains calcium chloride in an amount of less than 5 mol %, in particular 0.5 mol % to 4 mol %, particularly preferably 1.50 mol % to 2.25 mol %, based on the total amount of substance of the salt composition.

4. The salt composition comprises sodium carbonate (Na ２ CO ３ 4. The breeding facility according to claim 1 , characterized in that it contains up to 0.5 mol %, in particular 0.01 mol % to 0.15 mol %, particularly preferably 0.065 mol % sodium carbonate relative to the total amount of substance of the salt composition.

5. The salt composition comprises sodium bicarbonate (NaHCO ３ 5. The breeding facility according to claim 1 , characterized in that it contains up to 0.5 mol %, in particular up to 0.35 mol %, particularly preferably 0.20 mol % to 0.31 mol % of sodium bicarbonate, based on the total amount of substance of the salt composition.

6. The sulfate-low salt composition is preferably magnesium sulfate (MgSO ４ 6. The breeding facility according to claim 1, further comprising a salt composition having a content of magnesium sulfate of less than 5 mol %, particularly preferably between 4.15 mol % and 4.35 mol %, based on the total amount of substance of the salt composition.

7. The sulfate-free salt composition contains 7.5 mol % to 12 mol %, preferably 9.0 mol % to 10.0 mol % of magnesium chloride (MgCl ２ 6. The breeding facility according to claim 1, further comprising:

8. The sulfate-poor salt composition contains 4.0 mol % to 7.0 mol %, preferably 5.0 mol % to 6.0 mol % magnesium chloride (MgCl ２ 7. The breeding facility according to claim 1, further comprising:

9. A salt composition for producing salt water or brackish water for a facility for rearing aquatic organisms, in particular fish or crustaceans, comprising: The salt composition contains 70 mol% to 99.9 mol% sodium chloride (NaCl) and 0.1 mol% to 30 mol% magnesium chloride (MgCl ２ ) The salt composition is characterized in that it is sulfate-free or at least sulfate-low.

10. 11. Salt or brackish water for installations for rearing aquatic organisms, in particular fish or crustaceans, which can be produced or has been produced by the salt composition according to claim 10.

11. 11. The brackish or salt water according to claim 10, characterized in that the salinity of the brackish or salt water is between 0.10% and 5%, preferably between 2.5% and 3.5%.

12. A method for producing brackish or salt water for a facility for rearing aquatic organisms according to any one of claims 1 to 8, comprising the steps of:

10. A method according to claim 9, characterized in that the salt composition according to claim 9 is introduced into fresh water, in particular tap water, ground water or surface water, and the salinity is adjusted to 1.0% to 5.0%.

13. 10. Aquatic organisms, particularly fish or crustaceans, kept or raised in a facility for rearing aquatic organisms according to any one of claims 1 to 8, comprising brackish or salt water having a salinity of 0.1% to 5.0%, which is producible or produced using the salt composition according to claim 9.

14. 10. Use of the salt composition according to claim 9 for operating a facility for rearing said aquatic organisms.

15. Use of the brackish or salt water according to claim 10 or 11 for operating an installation for rearing said aquatic organisms.

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