A recirculating aquaculture system with improved feed transport and a method for transporting materials in a recirculating aquaculture system.

Abstract

To provide an aquaculture system for executing improved and gentle feed transport.SOLUTION: An aquaculture system 1 comprises a fish holding unit 2 fluidly connected to a water recirculation conduit 3, a water treatment unit 23, a water inlet and a feed storage unit 31. The system further comprises a feed loading part 30. When feed is loaded into the system at the feed loading part, it is transported to the fish holding unit. Alternatively, a feed transport method in the recirculating aquaculture system is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a system and method for transporting feed, and more particularly, to the transport of feed in a recirculating aquaculture system (RAS).

Background Art

[0002] Aquaculture fish and shellfish depend on the intake of all necessary nutrients contained in feed delivered to aquaculture farms such as, for example, cages floating in the sea, flow-throughs connected to rivers or ponds, or onshore facilities such as RAS facilities. Most devices currently used for transporting fish feed to feeding locations are pneumatic or mechanical. Usually, in the case of pneumatic transport, either a fan or an air compressor is used to blow feed pellets. As described in International Publication No. 2015067955, it is well known that when feed pellets are pneumatically transported, the pellets are prone to deterioration and up to 7% dust and fine powder are likely to be generated. Also, the pipes used for feed transport are worn by the friction between the pipe wall and the pellets.

[0003] Steel pipes are heavy, require additional supports and are expensive, while plastic pipes are inexpensive but require more maintenance and release microplastics into the feed and aquaculture farms. The generation of fine powder and dust from feed pellets is costly and must be minimized as much as possible. This corresponds to a loss of feed and essential / limiting nutrients and pollutes the surrounding environment. In the case of RAS facilities, furthermore, it stresses the mechanical filters and / or (micro)biological filters used to clean the water in the aquaculture system.

[0004] Another method of transporting fish feed is by hydropower transport, known from International Publication No. 2002056676, which concerns a system utilizing hydropower feeding to supply feed below the water surface, particularly relevant to demersal fish such as catfish, turbon, and halibut. Hydropower transport is also known from International Publication Nos. 2011064538 and 2015067955, which describe a method of using hydropower transport for aquaculture feed to impregnate dry fish feed pellets with water to improve digestibility. Impregnation of feed will not only allow water to enter the feed, but will also cause mass transfer, in which nutrients and oils will leach from the feed into the water.

[0005] International Publication No. 2016160141 discloses a modularized shrimp production system. This system comprises a production subunit module, a RAS module, a feed distribution module, and a computer control module. The modularized and integrated system forms a multi-stage synchronous, ultra-intensive shrimp production system controlled by a custom-designed cyber-physical platform. This system is expected to enable shrimp aquaculture by significantly reducing the total water volume per unit weight of shrimp produced compared to conventional technologies.

[0006] Nutrient loss is undesirable and incurs additional costs because more feed is needed to supply the necessary nutrients to the fish.

[0007] While oil leakage from feed is not ideal, it is acceptable when fish are raised in open water. However, in RAS facilities, for example, the oil settles in the filter, reducing filter efficiency. This can increase the amount of CO2 in the wash water, which can slow down fish growth.

[0008] Therefore, there is a need to develop methods for transporting feed more gently and efficiently, especially in RAS facilities. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2015067955 [Patent Document 2] International Publication No. 2002056676 [Patent Document 3] International Publication No. 2011064538 [Patent Document 4] International Publication No. 2016160141 [Overview of the Initiative]

[0010] The object of the present invention is to provide an aquaculture system that provides improved and gentle feed transport. Accordingly, according to a first aspect of the present invention, this object and other objects are achieved by an aquaculture system, which is The system comprises a water recirculation conduit, a water treatment unit, a water inlet, and a fish holding unit fluidly connected to a feed storage unit, further comprising a feed filling section located upstream of the water inlet or within the water recirculation conduit, wherein when feed is introduced into the system at the feed filling section, the feed is hydraulically transported to the fish holding unit, the water recirculation conduit comprises the water treatment unit, and the feed filling section is located downstream of the water treatment unit.

[0011] The fish holding unit, the water recirculation conduit, the water treatment unit, the water inlet, and the feed storage unit may be connected in series, or they may be connected in parallel. Similarly, the fish holding unit, the water recirculation conduit, the water treatment unit, the water inlet, and the feed storage unit may be connected in a combination of series and parallel. Therefore, for example, the water recirculation conduit may be provided by connecting the water treatment unit and the feed storage unit in series, or the water inlet may be connected to the fish holding unit.

[0012] Hydraulic feed transport has been shown to provide a gentler feed delivery and reduce the amount of dust and fine particles generated. This system has also been shown to effectively reduce feed loss and the energy required for transport. Furthermore, the use of plastic pipes without the risk of microplastic generation can significantly lower installation costs. In addition, the installation of plastic pipes requires far fewer supports than, for example, steel pipes. Moreover, when steel pipes are used, especially in RAS facilities designed for saltwater species such as grown salmon, the steel pipes are usually made of expensive, high-grade stainless steel to avoid corrosion. In addition, because feed damage by elbows is significantly less in this hydraulic system compared to conventional pneumatic transport systems, hydraulic transport offers flexibility in installation.

[0013] In a preferred embodiment, the feed filling section is placed within a conduit made of plastic material. Preferably, the conduit of the recirculation conduit is also made of plastic material. Plastics such as high-density PE, nylon, PVC, and POM can be used, but are not limited to these.

[0014] These advantages may also apply to aquaculture system facilities in which water is fully or partially recirculated internally. Aquaculture system using recirculated water may be referred to in the context of this invention as a “recirculating aquaculture system” (RAS). Thus, in one embodiment, the aquaculture system of this invention is an RAS. It will be apparent to those skilled in the art that these advantages also apply to different types of fish farming that have water transport pipelines that can be used for feed transport.

[0015] The term hydraulic transport is used to describe solid-liquid two-phase flow. In this context, solid-liquid two-phase flow consists of fish feed, for example, granules or pellets, and water. In this system, granular or pelletized feed is preferred, but other types of fish feed, such as clump feed, moist or slightly moist feed, or fish fillets, may also be used.

[0016] The fish holding unit described above may have any desired shape suitable for holding liquid. It may be, for example, a cylindrical unit or a rectangular prism-shaped unit. It may be a tank, container, aquarium, tub, etc., made from any material. It may also be a pond or depression where some filtration and / or washing takes place. The top of the fish holding unit may be open or may have a removable or fixed lid. When the system is used as needed, i.e., when used to raise fish, the aquaculture system contains water. The majority of the water is usually contained within the fish holding unit where the fish are raised. The type of water in the system is suitable for the species of fish being farmed. For saltwater fish, the water is adapted to resemble seawater, while for freshwater fish, the water is adapted to resemble freshwater. The quality and properties of the water can also be controlled, such as purity, O2 content, temperature, etc.

[0017] The recirculation conduit described above is a series of water conduits or water pipes suitable for transporting water to and from the fish holding unit. The recirculation conduit is fluidly connected to the fish holding unit and forms a water circuit. The recirculation conduit is connected to the fish holding unit via at least one opening that allows for water intake or drainage. Preferably, the water pipes within the recirculation conduit are used to continuously or intermittently drain water from the fish holding unit. The recirculation conduit through which the water passes may include one or more unit operations, after which the water is returned to the fish holding unit, i.e., the water is recirculated by the recirculation conduit. In this regard, the unit operations may be, but are not limited to, water treatment, such as the input of solids such as feed, or fluid transport means such as pumps. The point where water enters the recirculation conduit from the fish holding unit through the opening can be considered the starting point of the water circulation. From this starting point, the water flows through the conduit and at some point returns to the fish holding unit. The point where the water returns to the fish holding unit through the opening can be considered the ending point. It should be understood that the start and end points are contained within the loop created by the recirculation conduit, so that water may flow from the end point to the start point. After a certain residence time in the fish holding unit, the water re-enters the recirculation conduit at the start point. Residence times may be defined from any point within the recirculation conduit to any other point within the recirculation conduit.

[0018] When the terms upstream and downstream are used to describe, for example, the location of unit operation within a recirculation conduit, they refer to the starting point unless otherwise specified.

[0019] The recirculation conduit can be coupled to a single fish holding unit or the recirculation conduit may be used to couple several fish holding units together. In such cases, the fish holding units may be coupled in series or in parallel. If several fish holding units are connected by the recirculation conduit, the water from the fish holding units may be combined and treated within the same water treatment unit. Similarly, the feed may be introduced into a single water stream at the feed filling section and then distributed to a plurality of individual fish holding units. As described above, one type of unit operation included within the recirculation conduit may be a water treatment unit. The water treatment unit includes, but is not limited to, a series of treatment processes for maintaining water quality, such as biological filtration, solid removal, for example filtration, oxygen addition, pH control, temperature control, optional CO2 removal including heating and / or cooling, ultraviolet (UV) treatment and / or ozone treatment.

[0020] The recirculation conduit is not limited to recirculating water within a single fish holding unit. It may also flow water from a first fish holding unit to a second fish holding unit, preferably with a water treatment unit provided between the fish holding units. In this configuration, the fish holding units will be coupled in series such that the recirculation conduit or another recirculation conduit returns water from the second fish holding unit to the first fish holding unit.

[0021] The above water inlet may refer to the water inlet for supplying water to the aquaculture system. Usually, newly supplied water is supplied to the aquaculture system through the water inlet. The water inlet to the aquaculture system may be arranged anywhere within the aquaculture system, such as within the recirculation conduit or directly within the fish holding unit. When the water inlet is an inlet for adding newly supplied water to the aquaculture system, it is preferable to arrange this inlet upstream of the water treatment unit or within the water treatment unit so that the water quality of the inflowing water conforms to the system. The aquaculture system may also include a water outlet. The water outlet may be arranged anywhere within the aquaculture system, such as within the recirculation conduit or within the fish holding unit, or the water outlet may be included within both the fish holding unit and the recirculation conduit. The water outlet enables the flow of water out of the system. The aquaculture system may also have a composite conduit for water inlet and outlet. Usually, in a RAS facility, since it is costly to exchange the amount of water within the facility, the inlet for newly supplied water is small.

[0022] The above feed storage unit is used for storing fish feed. The feed storage unit may be of any shape or size suitable for storing feed in the RAS facility. Usually, the feed storage unit is a tank or a silo. If the feed is produced on-site in the RAS facility, the feed storage unit may be the container part of the feed production unit within the facility. Such a container part may function to hold at least the freshly produced feed. The feed storage unit is preferably arranged adjacent to the feed filling section. The above feed filling section is a conduit part where feed can be introduced into the conduit while water is flowing through the conduit. The feed may also be hydraulically transported from the feed storage unit to several fish holding units.

[0023] Feeding the feed from the feed storage unit into the water at the feed filling section can be achieved using feeding means, such as mechanical means like the feed screw of a conveyor, or by suction means. Examples of suction means include, for example, a Venturi injector, from which a negative pressure is obtained to create the flow of feed into the water. Alternatively, the feed may be drawn into the feed filling section using negative pressure obtained by a pump.

[0024] The feed filling section is the location within the conduit where the feed is introduced into the water flow. The feed is then hydraulically transported to the desired location along with the flow. When newly supplied water is added to the aquaculture system, the feed filling section may be located upstream of the water inlet, or it may be fluidly connected to the water inlet, so that the feed is hydraulically transported into the fish holding unit along with the newly supplied water. In RAS facilities, it is desirable to minimize the inflow of newly supplied water because this incurs additional costs. Typically, 99.5% of the water in an RAS facility is recirculated. The amount of newly supplied water added is only about 0.5% of the total water volume. Depending on the amount of fish in the aquaculture system, this water flow may not be sufficient to hydraulically transport a sufficient amount of feed. Therefore, in a preferred embodiment, the feed filling section is located within the water recirculation conduit. By recirculating water from the fish holding unit, the desired volumetric flow rate for hydraulic feed transport can be obtained without supplying additional newly supplied water. By controlling the desired volumetric flow rate, all parameters related to the water flow can generally be adapted in a manner suitable for hydraulic feed transport. For example, the flow may be adjusted to be gentler, resulting in less fine powder and / or liquid loss (such as oil loss). Another example would be controlling the flow to distribute the feed more widely. The increased volumetric flow rate due to recirculation allows for the use of conduits with a larger cross-sectional area at a water velocity suitable for the hydraulic transport of feed. When feed is hydraulically transported through conduits with a larger cross-sectional area, it is effectively distributed over a larger area / volume when it leaves the conduit and reaches the desired location. Therefore, a water flow through a conduit with a larger cross-sectional area at a water velocity suitable for the hydraulic transport of feed distributes the feed more widely compared to a water flow through a conduit with a smaller cross-sectional area at the same water velocity suitable for the hydraulic transport of feed. In addition to enabling a wider distribution area, the larger volumetric flow rate obtained by recirculation allows for a higher water velocity in the recirculating conduit, even when conduits with a larger cross-sectional area are used. A water flow passing through a conduit of a certain cross-sectional area at a higher velocity will distribute the feed more widely as the water containing the feed exits the conduit compared to a water flow passing through a conduit of the same cross-sectional area at a lower velocity.Wider feed distribution is advantageous because it allows for more even distribution of feed among the fish, resulting in a stock of fish with a smaller average size variation. This is valuable to the industry because it reduces the amount of small, unsaleable fish. Furthermore, it will shorten the time required to grow the fish to the minimum size required for market.

[0025] In aquaculture systems that minimize the flow of newly supplied inflowing water, it is preferable to treat the water to maintain good water quality. The fish holding unit is 200m 3 ~50,000m 3 It may contain water. Typically, industrial aquaculture systems have several fish holding units. Fish holding units can hold up to 5,000 m 3 Small fish holding unit, up to 15,000m 3 A medium-sized fish holding unit, or for example, 50,000 m 3 For example, 25,000-35,000m 3 A large fish holding unit, or a combination thereof, may be used. The recirculation and treatment of water within the fish holding unit depends not only on the density of fish within the unit but also on the quality of the feed. Fish density is the number of fish per unit volume of water within the fish holding unit. The water is recirculated and treated to maintain good water quality for the fish. If the fish density is low, water recirculation may be as low as, for example, 0.5 to 5 times / hour, while if the fish density is high, the water in the fish holding unit may be recirculated up to 20 times / hour. Similarly, if the feed quality is high and there is little oil and disintegrated pellet particles present in the water, water recirculation may be reduced. Therefore, 400 m³ per tank 3 / hour~100,000m 3 A recirculating water flow can be predicted per hour. This recirculating water flow is large enough to transport feed. Furthermore, since current RAS facilities already have such conduits, a feed filling section may be retrofitted to the conduits to provide an aquaculture system that uses hydroelectric transport of feed.

[0026] In a preferred embodiment, the water recirculation conduit comprises a water treatment unit located downstream of the starting point and upstream of the ending point, and further comprises a feed filling unit located downstream of the water treatment unit and upstream of the ending point. This configuration ensures that the feed is introduced into the water after the water treatment unit so that it is not damaged by different treatments. With sufficient water treatment, it is also possible to exchange treated water between different fish holding units without increasing the risk of infection between them. Thus, water from one fish holding unit can be used to hydropower-transport feed to another fish holding unit.

[0027] In a preferred embodiment, the recirculation conduit from the feed filling section to the feeding point has a substantially constant diameter and minimal height difference. In this way, abrupt pressure changes are avoided. Typically, the diameter of the pipe from the feed filling section to the feeding point is 25 mm to 130 mm, for example, 30 mm to 100 mm, preferably 50 mm to 60 mm. Usually, a pipe diameter of 50 mm to 60 mm is sufficient when transporting feed hydraulically to a single fish holding unit, but a pipe diameter of 100 mm or more may be required when transporting feed hydraulically to multiple fish holding units.

[0028] The height difference between the feed filling section and the feeding point is preferably 5 meters or less, more preferably 3 meters or less, for example, in the range of 0 to 3 meters. The length of the conduit from the feed filling section to the feeding point may vary depending on the design of the aquaculture system. Preferably, the distance is fairly small, such as in the range of 10 to 50 meters, but may be greater than 100 meters. A certain pressure drop can be expected in the conduit, but by avoiding abrupt pressure drops due to height differences or changes in pipe diameter, large-scale transfer of oil and nutrients from pellets to water caused by water impregnation of pellets is less likely to occur. The total pressure drop is usually 1 to 5 bar, but may reach up to 7 bar.

[0029] The feeding point is where fish in the fish holding unit can obtain feed. Therefore, this feeding point is located within the fish holding unit near the exit point opening. Typically, the greatest pressure drop for the pellets occurs at the feeding point. The pressure inside the fish holding unit is approximately 1 bar, but the pressure in the recirculation conduit increases or decreases due to water recirculation. When the pellets enter the fish holding unit at the feeding point from the recirculation conduit, they can experience a pressure drop of up to 7 bar. Typically, this pressure drop is smaller, such as 2-3 bar.

[0030] The inventors have discovered that a pressure drop occurs when pellets enter stagnant water, causing water to permeate the pellets and making it difficult for oils and nutrients to be released into the water. Therefore, it is important that the pressure drop in the conduit is small and stable. In a preferred embodiment, the pressure change in the recirculation conduit from the feed filling section to the end point is a maximum of 7 bar, for example, a maximum of 5 bar, preferably 3 bar or less, for example, 1 bar or less, for example, 0.5 bar or less, preferably less than 0.1 bar.

[0031] The small pressure change has the advantage of preventing water from impregnating the pellets. Consequently, the large-scale transfer of nutrients and oils from the pellets is reduced. Therefore, the amount of oil and / or nutrients in the water when using the hydraulic transport of feed according to the present invention is the same as when the feed is transported pneumatically or mechanically, and thus the water treatment units of existing RAS facilities are sufficient to treat the water.

[0032] Fish feeds such as pellets are often composed of dry material with a very low water content. Typically, dry pellets contain 5% to 10% water by weight. When pellets are placed in water, the water begins to penetrate the surface of the pellet and is absorbed by the dry material of the pellet or drawn into the porous structure of the pellet. This absorption of water into the pellet is called water impregnation. During hydraulic transport of pellets, it is desirable to keep the degree of water impregnation as low as possible. Water-impregnated pellets are softer than dry pellets or partially impregnated pellets. When pellets absorb water, the outer layer begins to disintegrate.

[0033] Preferably, the flow within the recirculating aquaculture system from the feed filling section to the feeding point has a Reynolds number of less than 500,000, preferably less than 200,000, more preferably less than 100,000, more preferably less than 50,000, and most preferably less than 20,000, for example, between 20,000 and 5,000.

[0034] In preferred embodiments, the residence time from the feed filling section to the feeding point is 3 minutes or less, preferably less than 1 minute, more preferably less than 30 seconds, most preferably less than 15 seconds, and most preferably about 5 seconds. The residence time from the feed filling section to the feeding point may also be called the feed residence time. Once the feed is introduced into the recirculation conduit at the feed filling section, the feed is transported along with the water flow from the feed filling section through the conduit to the fish holding tank. Residence time is the time from when the pellets are introduced into the water at the feed filling section until the feed enters the fish holding unit at the feeding point. Because the residence time of the feed in the water is short, for example, in the range of 5 seconds to 2 minutes, only a limited amount of water is absorbed on the surface of the pellets, and the pellets do not become water-impregnated. These embodiments are known to reduce nutrient and / or oil leakage as leakage increases with increasing residence time and / or Reynolds number of the flow.

[0035] In another aspect, the present invention relates to a method for transporting feed in a recirculating aquaculture system, wherein the method is - To supply water flow from the feed filling section of a recirculating aquaculture system to the feeding point. -In order to obtain a flow of feed containing water, the feed is introduced into the water flow in the feed filling section. - Transporting the above-mentioned water-containing feed to the feeding point using hydroelectric power, Includes, The above water flow is at least partially recirculated from the fish holding unit of the above-mentioned recirculating aquaculture system.

[0036] This method demonstrates an improvement in feed transport because the feed is transported more slowly than by pneumatic or mechanical transport methods, thereby reducing the amount of dust and fine particles generated. The recirculating aquaculture system provides a method for raising fish, such as saltwater fish, away from the sea in locations where access to seawater and freshwater is limited. By recirculating the water already contained in the system, this water flow can be used to hydropower the transport of feed to feeding points. The water may be recirculated in a recirculation conduit as described above, and the water flow may originate from the same fish holding unit or other fish holding units.

[0037] In a preferred embodiment, the method further includes a step of washing the water flow to obtain a wash water flow. This washing is preferably performed before introducing the feed into the water flow.

[0038] This method can be used in existing facilities. Typically, facilities are equipped with a recirculation conduit through which water from a fish holding unit is treated and recirculated back to the fish holding unit. A portion of the recirculation conduit, preferably located downstream of the water treatment unit, may then be made suitable for introducing feed into the water flow. Therefore, since existing conduits can be utilized, existing RAS facilities can be adapted to this method at minimal cost.

[0039] The recirculation conduit may be equipped with a water inlet for supplying newly supplied water to the water flow. Therefore, in an alternative embodiment, the water flow is water that has been at least partially recirculated from the fish holding unit of the aquaculture system. In an open RAS facility, water may be lost due to evaporation, and it is preferable to replenish the fish holding unit with water. In a particular embodiment, the amount of recirculated water is in the range of 90% to 99.9%, for example, freshwater is added in the range of 0.1% to 10% of the water. The amount of recirculated water is based on the total amount of water in the RAS. In other embodiments, the amount of recirculated water is in the range of 95% to 99.9%, for example, 98% to 99.9%, or 99% to 99.9%, or 99.3% to 99.7%.

[0040] The water flow described above may include water from the fish holding unit, treated water from the fish holding unit, water from other or some fish holding units, treated water from other or some fish holding units, newly supplied water, or any mixture thereof.

[0041] A circulating water flow can be obtained by using a pump. The use of pumps and methods for arranging them to obtain a suitable flow are known to those skilled in the art. For example, a pump can supply positive or negative relative pressure at a suitable location within an aquaculture system. One or more pumps may be placed anywhere in the recirculation conduit to obtain water recirculation, for example. To avoid damaging the feed, the pump may be placed upstream of the feed filling section. Alternatively, a gentle pump that allows the pellets to pass through without significant damage, such as a fish pump, may be placed downstream of the feed filling section. To minimize pellet impregnation, it is preferable to place the pump upstream of the feed filling section.

[0042] In a preferred embodiment, feed containing water is supplied to a fish holding unit containing water, so that the fish holding unit has a water surface, and there are feeding points at, above, or below the water surface. This allows the feed to be released according to where the type of fish in the fish holding unit eats. Therefore, the position of the feeding points can also be adjusted to the type of feeding; for example, pellets for floating fish can be fed near or above the water surface, while pellets for sinking fish can be fed below the water surface or near the bottom of the fish holding unit. If the fish eat near the water surface, the feed may be supplied above or just below the water surface. If the fish eat near the bottom, the feed may be supplied near the bottom of the fish holding unit.

[0043] In a preferred embodiment, two or more feeding points are positioned at different locations relative to the water surface. This is beneficial when uniform feeding of the fish is desired. The depth is measured perpendicular to the water surface toward the bottom of the fish holding unit, i.e., parallel to the direction of gravity.

[0044] In another preferred embodiment, the method further includes the step of treating water with oxygen to obtain a flow of oxygen-enriched water. This oxygenation may be combined with the water treatment unit described above, or it may be a separate unit located upstream of the feed filling section, for example. The following description will explain embodiments of the present invention with reference to schematic diagrams. [Brief explanation of the drawing]

[0045] [Figure 1] Figure 1 is a schematic diagram of an aquaculture system equipped with a water recirculation conduit according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of an aquaculture system equipped with two water recirculation conduits according to another embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram of an aquaculture system equipped with a water recirculation conduit according to yet another embodiment of the present invention. [Figure 4] Figure 4 is a schematic diagram of an aquaculture system equipped with a water recirculation conduit according to yet another embodiment of the present invention. [Figure 5] Figure 5 shows six schematic diagrams (5a-5f) of aquaculture systems according to different embodiments of the present invention. [Figure 6] Figure 6 shows six schematic diagrams (6a-6f) of aquaculture systems according to different embodiments of the present invention. [Figure 7] Figure 7 shows six schematic diagrams (7a-7f) of aquaculture systems according to different embodiments of the present invention. [Figure 8] Figure 8 shows five schematic diagrams (8a-8e) of aquaculture systems according to different embodiments of the present invention. [Figure 9] Figure 9 shows four schematic diagrams (9a-9d) of aquaculture systems according to different embodiments of the present invention. [Modes for carrying out the invention]

[0046] Referring first to Figure 1, a schematic diagram of an aquaculture system 1 according to an embodiment of the present invention is shown. The aquaculture system comprises a fish holding unit 2 in the form of a tank having an opening at the top. When the water holding unit 2 is used for its intended purpose, i.e., fish rearing, the water holding unit 2 contains water 99 and fish (not shown). A water recirculation conduit 3 is fluidly connected to the fish holding unit 2. The elements contained within the water recirculation conduit 3 are shown inside the dotted rectangle. When the water is recirculated, the water flows from the fish holding unit 2 into the recirculation conduit 3 at the starting point 10 and into the water treatment unit 23. Arrows indicate the conduits and the intended direction of water flow in the aquaculture system 1. The water returns from the water treatment unit 23 through the ending point 11 to the fish holding unit 2. In this particular embodiment, the starting point 10 is located in the water below the water surface 100.

[0047] The feed filling unit 30 is located downstream of the water treatment unit 23 and dispenses feed before the treated water returns to the fish holding unit 2 at the end point 11. A silo-type feed storage unit 31 is located adjacent to the feed filling unit 30. The feed storage unit 31 supplies feed to the feed filling unit 30. The feed filling unit 30 is equipped with feed dispensing means, such as venture injectors, for guiding the feed into the conduit. Details not shown or described will be readily apparent to those skilled in the art. Elements having the same or similar function have the same reference number.

[0048] Referring now to Figure 2, an aquaculture system 1 according to another embodiment of the present invention is shown. The aquaculture system 1 comprises a fish holding unit 2 having two water recirculation conduits 3. In the first water recirculation conduit 3, water flows from the fish holding unit 2 at a starting point 10 to a feed filling unit 30 from which feed is introduced into the water flow. The water containing the feed is then returned to the fish holding unit 2 at an ending point 11. A feed storage unit 31 in the form of a silo is positioned adjacent to the feed filling unit 30 from which the feed is introduced into the water flow. The amount of feed introduced into the water can be adjusted using an adjustable opening (not shown) of the silo. Alternatively, the amount of feed may be adjusted by the opening time of the opening. Alternatively, the feed may be measured by volume or weight before being introduced into the water. The feed filling unit 30 may have an opening in the conduit from which feed can be introduced into the water, or the conduit may be connected from the feed storage unit 31 to the feed filling unit.

[0049] In the second water recirculation unit 3, water flows from the fish holding unit 2 through the starting point 10 to the water treatment unit 23. The treated water is then returned to the fish holding unit 2 via the ending point 11. The illustrated aquaculture system 1 may be particularly beneficial when the water treatment unit 23 and the feed storage unit 31 are located far apart from each other. For example, in the aquaculture system 1, fish are often farmed using multiple fish holding units 2. Each fish holding unit 2 may have an independent water treatment unit 23 fluidly connected to it, while feed may be stored centrally in the facility. In this case, it may be more beneficial to have two recirculation conduits as shown. Water pumps 24 are located in both recirculation conduits 3. In the recirculation conduit 3 equipped with a feed filling section 30, the water pump 24 is located upstream of the feed filling section 30. In this design, the feed does not need to pass through the water pump 24 and is therefore not damaged by the water pump 24. If a gentle pump such as a fish pump is used as the water pump 24, it may be possible to place it downstream of the feed filling section 30 so that the feed can pass through the fish pump without being damaged. In a recirculation conduit 3 equipped with a water treatment unit 23, the water pump 24 is located downstream of the water treatment unit 23. Alternatively, the water pump 24 may be integrated into the water treatment unit 23 or located upstream of the water treatment unit 23.

[0050] Referring now to Figure 3, an aquaculture system 1 according to another embodiment of the present invention is shown. The water inlet 22 supplies water into the system 1. This water may be newly supplied water added to the aquaculture system 1. Alternatively, the water may come from another aquaculture system 1.

[0051] A feed filling unit 30 is located upstream of the water inlet 22. Therefore, feed can be hydraulically transported from the feed filling unit 30 to the fish holding unit 2 by, for example, supplying new water to the system 1.

[0052] The water recirculation conduit 3 is located adjacent to the fish holding unit 2. Water flows from the fish holding unit 2 through the starting point 10 to the water treatment unit 23. Water from the water treatment unit 23 may be returned to the fish holding unit 2 through the ending point 11. The water recirculation conduit is further connected to a water outlet 21 for removing water from the aquaculture system 1. A certain flow of water may be removed through the water outlet 21, or the outlet may be equipped with a valve (not shown) to open and close the water outlet. In this particular embodiment, the outlet 21 is located within the water treatment unit 23. The location of this outlet 21 makes it possible to take out treated or partially treated water. However, the location of the outlet 21 may be anywhere within the recirculation conduit 3, or it may be adjacent to the fish holding unit 2. The location of the outlet is mainly determined by the desired water quality to be taken out of the aquaculture system 1. Therefore, the outlet 21 may be located upstream or downstream of, for example, a biofilter unit, a mechanical filter unit, an oxygenation unit, a pH control unit, a temperature control unit, an ultraviolet (UV) treatment unit, a CO2 stripping unit, and / or an ozone treatment unit. Alternatively, the system outlet may be located upstream or downstream of the water treatment unit 23. The water pump 24 is located in the recirculation conduit upstream of the water treatment unit, but can be located anywhere in the recirculation conduit 3 downstream of the starting point 10.

[0053] Referring here to Figure 4, an aquaculture system 1 according to another embodiment of the present invention is shown. The aquaculture system 1 has a fish holding unit 2 equipped with a water recirculation conduit 3. When the system 1 is used for its intended purpose, i.e., fish rearing, the system contains a desired amount of water located from the water surface 100 to the bottom of the fish holding unit 2. Water can flow from the fish holding unit 2 through a starting point 10 to a water treatment unit 23 in the water recirculation conduit 3. The water treatment unit 23 treats the water to supply treated water of a desired purity and quality. The treated water is then returned to the fish holding unit 2 via a plurality of termination points 11. Feed is added to the treated water in a feed filling section 30. The plurality of termination points 11 distribute the water and feed from the feed filling section 30 to different locations within the fish holding unit 2. In this particular embodiment, one termination point 11 is located above the water surface 100, and two termination points 11 are located at different depths in the water of the fish holding unit 2. This design is beneficial when the fish holding unit 2 contains many fish to be fed simultaneously. Different fish species may also prefer to find / eat feed at different depths. In the illustrated embodiment, recirculated water is used to enable hydroelectric transport of feed to several depths / locations within the fish holding unit 2.

[0054] In Figure 5, six different embodiments of the present invention (Figures 5a to 5f) are shown to illustrate different configurations of the recirculation conduit 3. The recirculation conduit 3 may have several termination points 11 at different locations above or below the water surface 100, and / or openings at different depths below the water surface 100, or at different locations above the water surface 100. In Figure 5e, the water flow is divided into two flows after the water treatment unit 23. The first flow returns directly to the fish holding unit 2, while the second flow returns to the fish holding unit 2 after feed has been added to the water flow in the feed filling section 30. It may be desirable not to continuously feed fish in the fish holding unit 2. In this case, the second flow may be provided with a valve located upstream of the feed filling section. This valve can be adjusted to an open or closed position, thereby opening and closing the second flow of water. The opening and closing of the conduit by the valve is particularly important when the system is subjected to clean-in-place (CIP) cleaning to prevent cleaning fluids such as chemicals or hot water from entering the fish holding unit 2.

[0055] Figure 6 shows six embodiments of the present invention (Figures 6a to 6f). Figure 6d shows a preferred embodiment in which the oxygenation unit 40 is connected to the recirculation conduit 3 near the end point 11. The oxygenation unit 40 may be located either downstream or upstream of the feed filling section 30. This allows the oxygenated water flowing into the fish holding unit 2 to increase the overall proportion of oxygenated water in the fish holding unit 2. Alternatively, the oxygenation unit 40 may be provided in the water treatment unit 23. Alternatively, the oxygenation unit 40 may be located in the recirculation conduit without the feed filling section, or upstream of the water inlet 22.

[0056] Figure 7 shows six other embodiments of the present invention (Figures 7a to 7f). In the preferred embodiment shown in Figure 7e, the water recirculation conduit 3 is not present in the fish holding unit 2. Feed is introduced into the water inlet 22 above the feed filling section 30. Freshly supplied water or water from another aquaculture system 1 may be supplied from the inlet. Away from the inlet 22 and the feed filling section 30, the water exits the fish holding unit 2 via the outlet 21.

[0057] Figure 8 shows five other embodiments (Figures 8a to 8e). In the preferred embodiment shown in Figure 8b, water flows from the fish holding unit 2 to the water treatment unit 23, and then from the water treatment unit 23 back to the fish holding unit 2 via the same water conduit. In this case, the starting point 10 and ending point 11 for recirculating water to and from the fish holding unit 2 are in the same location. In this embodiment, the flow is redirected in two different directions. When the water flow is directed from the water treatment unit 23 to the fish holding unit 2, feed can be added to the water via the feed storage unit and feed filling unit 30. When the water flow is directed from the fish holding tank 2 to the water treatment unit 23, no feed is added. This can be controlled by a valve that can be opened and closed and a pump that can change the direction of the water flow.

[0058] In another preferred embodiment shown in Figure 8c, the two fish holding units 2 are fluidly connected by a water conduit, allowing water to flow from the first fish holding unit 2 to the second fish holding unit 2. Another water conduit allows water to flow from the second fish holding unit 2 to a water treatment unit 23. The water flowing from the water treatment unit 23 into the first fish holding unit 2 can be supplied with feed from the feed storage unit 31 in the feed filling section 30. Alternatively, each of the two water conduits may have a feed filling section 30 and a feed storage unit 31. In this embodiment, the recirculation conduit 3 consists of several water conduits that allow the water flow to recirculate from the first fish holding unit 2 to the second fish holding unit 2 and back to the first fish holding unit 2.

[0059] In another preferred embodiment shown in Figure 8e, the combined water inlet 22 and water outlet 21 are located adjacent to the water treatment unit 23. The treated water is returned from the water treatment unit 23 to the fish holding unit 2 via the termination point 11. The feed storage unit 31 is fluidly connected to the recirculation conduit 3 in the feed filling section 30, allowing for the replenishment of feed into the treated water. Furthermore, separate conduits for the water inlet 22 and water outlet 21 may be connected to the water treatment unit 23. Alternatively, the combined water inlet 22 and water outlet 21 may be located at any other location in the fish holding unit 2.

[0060] Figure 9 shows four other embodiments (Figures 9a to 9d). In the preferred embodiment shown in Figure 9a, two fish holding units 2 are connected to the same water treatment unit 23. In such embodiments, water can be exchanged between the first fish holding unit 2 and the second fish holding unit 2 by flowing through the water treatment unit 23.

[0061] The feed is introduced into the water flow exiting the water treatment unit 23 through two feed filling sections 30, which are fluidly connected to a single feed storage unit 31.

[0062] In another preferred embodiment of the present invention shown in Figure 9b, three fish holding units 2 are provided in the same aquaculture system 1. Additional fish holding units 2 may be included in the same aquaculture system 1 depending on the quantity of fish to be raised. Each fish holding unit 2 has an individual water recirculation conduit 3, which has a feed storage unit 31 and a feed filling section 30 that allows for the replenishment of feed to the individual fish holding unit 2. Furthermore, each of the three fish holding units 2 is provided in a common water recirculation conduit 3 in which a water treatment unit 23 is located. The treated water exits the water treatment unit 23 and recirculates to the three fish holding units 2 via branched water conduits. In the embodiment of Figure 9b, the fish in the three fish holding units 2 can be fed different feeds and / or different feeding rates while the water in the fish holding units 2 is treated with a single water treatment unit 23.

[0063] In a more preferred embodiment shown in Figure 9c, the two fish holding units 2 are connected by a composite recirculation conduit 3. Each of the two fish holding units 2 is provided with a pair of start points 10 and end points 11.

[0064] Water flows from each fish holding unit 2 to a single water treatment unit 23, where the two water flows may be mixed. The treated water then flows from the water treatment unit 23 to a single feed filling unit 30, where feed is supplied from the feed storage unit 31. From the feed filling unit 30, the water conduit is divided into two conduits for water flow, which are fed back to each of the two fish holding units 2 via the termination point 11. The water inlet branches into the two water inlets downstream of the feed filling unit 30, enabling feed supply to both aquaculture systems 1. The present invention is not limited to the embodiments shown and described above, and various modifications and combinations may be made. [Explanation of Symbols]

[0065] 1. Aquaculture Systems 2 Fish holding units 3 Water recirculation conduit 10 Starting point 11 End Point 21 Exit 22 Entrance 23 Water Treatment Unit 24 pumps 30 Feed filling section 31 Feed Storage Unit 40 Oxygenated Water Unit 99 water 100 water surface

[0066] [Example] [Example 1] - Hydraulic transport of feed in RAS Feed (pellets) stored in the feed storage unit was introduced into the RAS conduit via a lobe pump or ejector. The amount of water relative to the pellets was varied in the same way as the water flow (hereinafter referred to as the water-to-pellet weight ratio). Liquid loss, loss due to fine powder generation, and holding time were measured. The results are shown in Table 1 below.

[0067] [Table 1]

[0068] Here, "Lobe" refers to the use of a lobe pump (which draws pellets from a feed storage unit and stores them in water). The term "ejector" refers to the use of an ejector to introduce pellets into the conduit (by sucking the pellets into the water flow within the conduit). The ejector is positioned after the conduit pump, thereby eliminating the need for the pellets to pass through the conduit pump.

[0069] Loss, or liquid loss, refers, for example, to weight loss due to oil released from pellets in the water flow within a conduit. Fine particles refer to weight loss of pellets due to the water flow in the conduit, such as pellet fragments, dust, and torn pieces.

[0070] Velocity refers to the flow rate of the water flow accompanied by the pellets. Retention time refers to the time the pellet is held in the water flow within the conduit.

[0071] conclusion Hydraulic transport of pellets generally generates very little fine powder and has minimal liquid loss, even with different water-to-pellet ratios. The invention described in the original claims of this application is listed below. [1] Aquaculture system, It includes a water recirculation conduit, a water treatment unit, a water inlet, and a fish holding unit that is fluidly connected to the feed storage unit. The system further comprises a feed filling section located upstream of the water inlet or within the water recirculation conduit, wherein when feed is introduced into the system from the feed filling section, the feed is hydraulically transported to the fish holding unit, the water recirculation conduit comprises the water treatment unit, and the feed filling section is located downstream of the water treatment unit. Aquaculture systems. [2] The water treatment unit comprises a biofilter treatment unit, a solids removal unit, a pH control unit, a temperature control unit, an ultraviolet (UV) treatment unit, an oxygen addition unit, and CO 2 The aquaculture system according to [1], comprising one or more of a stripping unit and an ozone treatment unit. [3] The aquaculture system according to [1] or [2], wherein the fish holding unit is fluidly connected to one or more further fish holding units, and the fish holding units are optionally connected in series, in parallel, or in combination thereof. [4] The aquaculture system according to any one of [1] to [3], wherein the conduit in the aquaculture system located downstream of the feed filling section is made of plastic material. [5] A method for transporting feed in a recirculating aquaculture system, The steps include supplying water flow from the feed filling section of the aforementioned recirculating aquaculture system to the feeding point, In order to obtain a flow of feed containing water, the feed is introduced into the water flow in the feed filling section, The steps include: transporting the feed containing the water to the feeding point using hydropower; Includes, A method for transporting feed that is at least partially recirculated from the fish holding unit of the recirculating aquaculture system, wherein the water flow is used for transporting feed. [6] In order to obtain a flow of washing water, before adding the feed to the water flow, the step of washing the water flow, The method for transporting feed as described in [5], further comprising: [7] The method for transporting feed according to [5] or [6], wherein the amount of recirculated water is in the range of 90% to 99.9% based on the total amount of water in the recirculating aquaculture system. [8] The step of washing the water flow includes biofiltration, removal of solids, pH control, temperature control, ultraviolet (UV) treatment, CO 2 A method for transporting feed according to [6] or [7], comprising stripping and one or more of ozone treatment. [9] A method for transporting feed according to any one of [5] to [8], wherein the change in pressure within the recirculating aquaculture system from the feed filling section to the feeding point is a maximum of 7 bar.

[10] A method for transporting feed according to any one of [5] to [9], wherein the residence time from the feed filling section to the feeding point is 3 minutes or less.

[11] A method for transporting feed according to any one of [5] to

[10] , wherein the feed containing water is supplied to the fish holding unit having a water surface, and the feeding point is on the water surface, or above or below the water surface.

[12] A method for transporting feed according to any one of [5] to

[11] , wherein two or more feeding points are arranged at different positions relative to the water surface.

[13] A method for transporting feed according to any one of items [5] to

[12] , wherein the Reynolds number is less than 500,000.

[14] A method for transporting feed described in any one of [5] to

[13] , wherein the Reynolds number is in the range of 5,000 to 20,000.

[15] A method for transporting feed according to any one of [5] to

[14] , wherein the water in the recirculating aquaculture system is recirculated 0.5 to 20 times per hour.

[16] A method for transporting feed according to any one of [5] to

[15] , wherein the feed has a water content in the range of 5% w / w to 10% w / w based on the mass of the feed.

Claims

1. A first water recirculation conduit having a first pump, a feed filling section, a start point and an end point, with the vicinity of the opening of the end point serving as a feeding point, further comprising a water treatment unit, a water inlet, a feed storage unit fluidly connected to the first water recirculation conduit for storing fish feed pellets, and 200m ３ ~50,000m ３ A recirculating aquaculture system comprising a fish holding unit containing water, The water treatment unit is located in the first water recirculation conduit, and the feed filling unit is located downstream of the water treatment unit in the first water recirculation conduit. When fish feed pellets are introduced into the feed filling unit, the fish feed pellets are transported hydraulically from the feed filling unit to the feeding point as a solid-liquid two-phase flow. or The fish holding unit is further provided with a second water recirculation conduit fluidly connected, the water treatment unit and a second pump are arranged within the second water recirculation conduit, and when fish feed pellets are introduced into the feed filling section, the fish feed pellets are hydraulically transported from the feed filling section to the feeding point as a solid-liquid two-phase flow. A recirculating aquaculture system.

2. The water treatment unit includes a biofilter treatment unit, a solids removal unit, a pH control unit, a temperature control unit, an ultraviolet (UV) treatment unit, an oxygen addition unit, and CO ２ Including one or more of a stripping unit and an ozone treatment unit, The recirculating aquaculture system according to claim 1.

3. The fish-holding unit is fluidly connected to one or more further fish-holding units, and the fish-holding units are optionally connected in series, in parallel, or in combination thereof. The recirculating aquaculture system according to claim 1.

4. The conduit in the recirculating aquaculture system located downstream of the feed filling section is made of plastic material. The recirculating aquaculture system according to claim 1.

5. The residence time of the feed from at least one of the feed filling sections of the first water recirculation conduit and the second water recirculation conduit to the feeding point is 3 minutes or less. The recirculating aquaculture system according to claim 1.

6. The fish holding unit has a water surface, The feeding point is located on or below the water surface. The recirculating aquaculture system according to claim 1.

7. The Reynolds number between the feed filling section and the feeding point is less than 500,000. The recirculating aquaculture system according to claim 1.

8. The Reynolds number between the feed filling section and the feeding point is in the range of 5,000 to 20,000. The recirculating aquaculture system according to claim 1.

9. At least one of the first water recirculation conduit and the second water recirculation conduit is configured to operate at a total pressure of up to 7 bar from the feed filling section to the feeding point. The recirculating aquaculture system according to claim 1.

10. The fish feed pellet has a water content in the range of 5% w / w to 10% w / w based on the mass of the fish feed pellet. The recirculating aquaculture system according to claim 1.

11. The solid-liquid two-phase flow consists of the fish feed pellets and water. The recirculating aquaculture system according to claim 1.

12. The recirculating aquaculture system according to claim 1, wherein each of the water recirculation conduits has a diameter of 25 mm to 130 mm from the feed filling section to the feeding point.

13. The recirculating aquaculture system according to Claim 1, wherein the amount of water recirculated by each water recirculation conduit is in the range of 90% to 99.9% of the total water volume.

14. A method for transporting feed in a recirculating aquaculture system according to any one of claims 1 to 13, The steps include supplying water flow from the feed filling section of the aforementioned recirculating aquaculture system to the feeding point, A step of supplying feed consisting of fish feed pellets, In order to obtain a flow of feed containing water, the feed is introduced into the water flow in the feed filling section, The steps include: transporting the feed containing the water from the feed filling unit to the feeding point using hydraulic power; Includes, The water flow is at least partially recirculated from the fish holding unit of the recirculating aquaculture system. Methods for transporting animal feed.

15. In order to obtain a flow of washing water, before adding the feed to the water flow, the water flow is washed. Further including, The method for transporting feed according to claim 14.

Images