Drain assembly for an aquaculture system and method

Abstract

An aquaculture system, flow-through partial use and particularly a recirculating aquaculture system, for treating an aqueous stream for the farming of aquatic organisms having a containment for retaining a rotating body of water and a drain (1) for selective opening and closing to allow periodic removal of larger solid waste, dead organisms. The drain includes an assembly having an outlet aperture in the containment which may be selectively opened and closed or moved into and out of the containment thereby to enable expeditious removal of larger solids from the containment.

Description

[0001] DRAIN ASSEMBLY FOR AN AQUACULTURE SYSTEM AND METHOD

[0002] This invention relates to a drain assembly for use in an aquaculture system for the removal of unwanted material from the system and to a method of farming aquatic organisms in an aquaculture system having a novel drain assembly. The invention particularly relates to a recirculating aquaculture system, a flow-through system and a partial-flow system using seawater, freshwater or brackish water having a novel drain assembly.

[0003] Aquaculture or aquafarming is a controlled process of cultivating aquatic organisms, for example, fish, crustaceans and shellfish, and may also be used for a variety of purposes including managing habitat and in regeneration of wild populations of aquatic organisms. Aquaculture may be carried out in a range of salt water, fresh and brackish water environments depending on the organisms under cultivation. Large-scale tanks, typically circular in cross-section, are commonly employed and find extensive use in the commercial production of fish and other aquatic organisms for the food sector. As the human population continues to grow rapidly and demand for sustainable, environmentally friendly, high quality protein grows accordingly, the demand for fish, crustaceans and other organisms produced by aquaculture is expected to grow markedly in the coming years, creating increasing demand for farmed fish, crustaceans and the like.

[0004] Conventional aquaculture systems may be of the recirculating type in which water inflow and outflow is retained within a closed system, flow-through type in which water is generally used once; net pen aquaculture systems are located within in a body of water, for example a loch, lake or sea environment, and are open to the environmental conditions, floating closed containment systems are also known wherein water from the body of water is brought into the aquaculture system and discharged from the system back into the external body of water. Partial flow-through or re-use aquaculture systems in which a higher percentage of water is discharged and the remaining water is treated and reused are also known. Recirculating aquaculture systems typically involve provision of large-scale water tanks equipped with filtration, internally or externally to recirculate and to treat the water for reuse and careful control of water conditions to optimise growth of the aquatic organisms. Water enters the tank through an inlet, and exits the tank via a drain to then be treated and recirculated to the tank.

[0005] Tanks have one or more drains through which water and small solid materials, for example faeces, uneaten feed and the like, may pass. Larger solid unwanted materials, for example deceased, injured or diseased animals, exoskeletons of crustaceans and the like, must also be removable from the tank. Water and smaller solids may be removed in one drain and suitably are removable together in a single assembly in a tank to reduce complexity and costs of construction and provision of utilities and conduits from the tank.

[0006] Suitably, the drain is located at or near the centre of the tank in which water rotates such that unwanted solids are urged towards the drain for removal from the tank. In raceway tanks the drains maybe cover the width of the tank in multiples ie every 2-3m in a 20x4m raceway Unwanted solids, particularly deceased fin fish and crustaceans may cause the drain to block, risking impaired operation and heightened risk of infection or disease with corresponding risk to the live animals in the tank and a reduction in water quality. Typically, mortalities are either removed manually or in some cases, for example with salmonids which will not usually swim up a pipe, a pipe or pipes are set permanently into the tank, leading typically from the centre to side of the tank (or vertically) where the mortalities are collected, for example in a mesh type box. Manual removal interrupts operation of the tank and is labour intensive and “in-tank” assemblies may interfere with the flow of the rotating body of water in the tank, be prone to fouling and, in any event are not suitable for cultivation of nonsalmonid species. There is a need to improve the removal of unwanted solids from aquaculture systems by reducing blockages and reducing or avoiding the unintended removal of live animals under cultivation from the tank with the unwanted material without resorting to manual removal of such materials.

[0007] We have now found that the disadvantages of manual removal and the known pipe arrangements may be reduced or overcome by providing a drain assembly which is selectively openable in the tank and permits the automatic removal of unwanted solids whilst reducing the risk of loss of live animals.

[0008] In a first aspect, the invention provides an aquaculture system for supporting aquatic organisms comprising: a containment comprising a side wall and a floor defining a containment zone for retaining a body of water to provide habitat for the aquatic organisms; at least one inlet for receiving water into the containment; at least one drain defining a drain zone located in the floor of the containment for removing solid waste from the aquatic organisms, the drain comprising an assembly comprising a orifice adapted to, in use, selectively allow passage of larger solids from the containment zone into the drain zone. The drain zone may be separated from the containment zone by drain mouth comprising a grill or a filter to enable continuous egress of water and small solids from the containment zone into the drain zone through the filter or grill. In alternative embodiments, the drain zone and containment zone may be separated by a solid drain cover, at least a part of which is movable to permit fluid communication between the containment zone and the drain zone.

[0009] The larger unwanted solids in the containment zone are removed via the orifice in the assembly. In one embodiment, the assembly comprises a conduit having the orifice therein. Suitably, the conduit is located at least in part in the drain zone and the orifice is in fluid communication with the containment zone. The conduit may extend to the boundary between the containment zone and the drain zone. In another embodiment, the conduit may be located in part, in the containment zone and in part in the drain zone with the orifice being located in that part of the conduit in the containment zone. The orifice is selectively openable to allow unwanted solids such as debris, dead animal and diseased animals to be removed from the containment zone via the orifice and into the conduit and thereby be removed from the system. The larger solids are suitably urged towards the orifice due to the flow of the body of water typically by rotation of the body of water moving the unwanted solids and debris radially towards the axis of rotation of the body of water. Preferably, the drain is located at or near the axis of rotation or intended axis of rotation of the body of water.

[0010] The orifice may be of any shape but is preferably circular, ellipsoidal, square or rectangular. The orifice is suitably dimensioned to allow the passage of larger solids, for example mortalities of the animal under cultivation whereby the size of the orifice and, where applicable, the height or depth to which the assembly needs to be moved to bring the orifice into fluid communication with or locate within the containment zone is determined by the particular application and the size of the animals under cultivation. For example, for the cultivation of crustaceans, the orifice suitably has a length and width or a diameter of up to 100mm, more preferably in the range 5 to 50mm. For smaller species, the orifice may have a length and width or a diameter of 1 to 5mm, for example 2 to 3mm. When cultivating salmonids, the orifice may have a length and width or a diameter of 100 to 500mm depending on the stage in the growth cycle ie the size of the animal under cultivation.

[0011] The orifice may be opened fully or partially to determine the rate, quantity or size of solids which pass through it. Suitably, the conduit comprises a barrier for the orifice, the barrier cover being moveable between an open position and a closed position to respectively open and close the orifice. The barrier may comprise a sleeve adapted to be moveable along the conduit to selectively open and close the orifice.

[0012] In another embodiment, the barrier comprises a plug adapted to be movable into the orifice to close it and away from the orifice to open it.

[0013] In a further embodiment, the barrier may comprise a trap door, adapted to be movable into the orifice to close it and away from the orifice to open it. In another embodiment, the conduit extends to the boundary of the containment zone and the drain zone and the orifice is located at the boundary and closed by the trap door which is configured to stay in a closed position thereby acting as a barrier between the drain zone and the containment zone, but openable upon application of force to the trap door, for example by unwanted solids being moved on to the trap door whereby it is urged open by the weight of the solids thereby enabling he unwanted solids to pass from the containment zone to the drain zone. Upon passage of the solids, the trap door suitably closes. The trap door is suitably operatively linked to resilient means which urge the trap door into a closed position ad which may be set or calibrated such that upon a predetermined force being applied to the trap door, the tap door opens, the solids pass into the drain zone and the force on the trap door is reduced such that the resilient means closes the trap door, pending build up of further unwanted solids on the containment side of the trap door.

[0014] Suitably, the assembly comprises resilient means to urge the barrier into the closed position, for example by sliding a sleeve along the conduit or urging a trap door to a closed position. Preferably, the resilient means comprises a spring or a pneumatic or hydraulic ram.

[0015] In one embodiment, the barrier may be remotely activated, preferably mechanically or electronically by remote means to selectively activate the barrier to move between the closed position and the open position.

[0016] In another embodiment, the conduit may be located in the drain zone and be selectively movable to a position such that part of the conduit comprising the orifice is located in the containment zone and part of the conduit is located in the drain zone. In this embodiment, the orifice may be open without a barrier as the orifice becomes inaccessible to solids by being moved from the containment zone to the drain zone. The term “selectively openable” accordingly means that the orifice is in communication with the containment zone such that solids may pass through the opening and is not limited to the case where the orifice itself blocked by a door or other barrier. In particular, movement of the drain comprising the orifice from a location where the orifice is in the containment zone to a location where the orifice is in the drain zone and not accessible by solids in the containment zone is encompassed within the scope of the invention. The conduit is movable such that the part of the conduit having the orifice is located in the drain zone in the closed configuration and movable into the containment zone such that the orifice permits egress of solids from the containment zone directly into the orifice. The conduit is suitably periodically moved and may be carried out whenever desired, depending on when the level of unwanted solids has built up to undesirable levels.

[0017] The drain may comprise a drain mouth which defines a boundary between the containment zone and drain zone through which water and smaller solids such as faeces and uneaten food may pass. The drain mouth is suitably covered with a filter, preferably a gauze, mesh, filter or array of apertures sized to allow smaller solids to pass therethrough with water but to retain the live animals and larger solids such as mortalities, diseased animals and parts of carcasses, claims wherein the filter comprises a screen. The drain mouth may be closed by a solid drain cover whereby water may leave the containment zone only via the orifice in the drain assembly.

[0018] The filter provides a means of continual outflow of water and smaller solids with the orifice in the assembly enabling removal of larger solids. The selective opening of the orifice allows periodic removal of larger solids and thereby reduces the risk of blockage 4and the need for manual removal of larger solids.

[0019] Suitably the drain mouth is between 1 and 25%, preferably 5 to 15%, for example 10% of the diameter or maximum dimension of the floor of the containment.

[0020] Suitably, the system comprises means to selectively close and open the drain mouth, preferably a movable cover which is remotely operable to move between a closed position in which the drain mouth is closed and an open position in which the drain mouth is open to flow of water and smaller solids through the filter. When the drain mouth is closed, water and solids may only leave the containment via the drain by passing through the orifice.

[0021] The body of water is suitably rotatable, suitably by impetus created by the directional inflow of water to the containment. The drain is suitably located in the floor of the containment at the intended axis of rotation of the body of water, typically towards and preferably at the centre of the containment. Where the containment comprises multiple zones, each with its own body of rotatable water, a drain is suitably located in each zone so as to provide a means of removing unwanted solids from each zone.

[0022] Suitably, the drain zone comprises two discrete zones; a water outlet zone and a solid outlet zone. The water outlet zone is suitably in communication with the containment zone through the drain mouth and filter but outside the conduit and the solid outlet zone is in communication with the containment zone exclusively via the orifice. The water and smaller solids pass through the drain mouth and filter into the water outlet zone and may be treated or processed to remove solids and other undesirable components with the water being recycled to the containment zone, optionally after further treatment for example to include food, nutrients or other desirable materials for treating or feeding the animal species.

[0023] Suitably, the material passing into the solid outlet zone is removed from the system and, preferably, does not come into contact with the water in the water outlet zone to reduce the risk of contamination or inadvertently recycling unwanted solids.

[0024] Solids removed from the solid outlet zone and the water outlet zone in the drain may be removed from the system separately after passing through the respective zones. Providing common supply or outlet and waste removal suitably reduces engineering complexity and cost.

[0025] The aquaculture system of the invention suitably also enables supply and withdrawal conduits and other service conduits and ancillary engineering to be shared between the cells, providing improved yield of farmed organisms for a given footprint or surface area and reduced capital and operating costs for a given yield as compared to conventional systems.

[0026] The inlet for feeding water into the containment may be of any arrangement but suitably comprises one or more nozzles. The term “nozzle” is employed herein to refer to any means defining an aperture or inlet for water to pass into the cell, suitably in a controllable direction providing impetus to rotate the body of water in the cell.

[0027] The nozzles(s) are suitably located within the containment and oriented to provide water in flow in a direction which will rotate the body of water. Preferably the inlet is oriented such that water is directed in a tangential or circumferential direction relative to the containment. The inlet may comprise a plurality of nozzles located at or near the containment wall and aligned to provide a flow of water in a circumferential direction thereby to impart force to rotate the body of water in the containment.

[0028] In a preferred arrangement, the inlet comprises a plurality of nozzles aligned in a horizontal array and / or comprises a plurality of nozzles arranged in a vertical array. Suitably, the nozzles extend from a vertical axis and are orthogonal to each other. The inlet preferably comprises at least 3 nozzles wherein the nozzles are independently arranged at an angle of 0 to 45° relative to the containment wall adjacent to the nozzle. Preferably, adjacent nozzles are arranged at an angle of 90 to 22.5 degrees in the horizontal, relative to adjacent nozzles, when viewed in a vertical direction.

[0029] Suitably, the drain may receive all of the water flow from the containment that leaves the containment zone, especially where the aquaculture system is of the “flow-through” type. The term “flow-through” refers to an aquaculture system in which water flows into the containment zone from an external source, for example a river or stream, lake, spring, well and sea water source and in due course flows out of the containment zone, typically under gravity and is not recycled. In one embodiment, the drain may receive not more than 30%, preferably not more than 20%, more preferably 2 to 10% of the water flow within the containment. The larger solids which are removed from the containment via the assembly suitably comprises at least 80%, preferably at least 90%, especially at least 95%, for example more than 99% of the total solids waste being removed via the orifice and a minor proportion of the material total being water.

[0030] Suitably, the containment may be circular or polygonal or part circular, part polygonal shape, preferably octagonal, dodecagonal or hexadecagon. The containment suitably is operably connected to means for supply to the containment of water and optionally other components, for example oxygen, nutrients and the like and for removal of water, waste and optionally other components from the containment via the drain and optionally a water outlet .The floor of the containment may be level or comprise areas or the whole of the floor sloping radially downwards from the periphery towards a low point in the middle area, for example the centre, whereby solids. Particularly mortalities are settled at the bottom and are urged under gravity and the centripetal force generated by the rotating water to the drain for removal.

[0031] In another embodiment, the containment may comprise multiple cells, for example as described in pending application PCT / EP2022 / 078392. In one embodiment, the containment comprises a plurality of cells, preferably 4 cells, defined within the containment, each cell being configured to hold a body of water which is rotatable within the cell, each cell being in fluid communication with at least one other adjacent cell. The containment suitably has at least one inlet for receiving water into each cell configured to allow the body of water in that cell to be rotatable, Each cell suitably comprises one drain as described herein for removing larger solids such as mortalities and diseased animals and water from the containment.

[0032] Where the containment comprises a plurality of cells, suitably, the containment comprises a base, a peripheral side wall and internal walls located so as to define the plurality of cells within the containment. Preferably each cell is shaped such that a body of water in the cell is rotatable within the cell, the cell being defined by internal walls, optionally a portion of the peripheral wall and at least one space in the walls to enable fluid communication with an adjacent cell. Each cell is defined by a portion of the peripheral wall, with at least two internal walls extending from the peripheral wall towards the inner area of the containment, and a further wall which extends to the two internal walls with a space between the further wall and the internal walls.

[0033] Preferably, the further wall for each cell is provided by an adjacent tank or preferably a structure comprising a water outlet. The structure is suitably located between two or more cells and, preferably is located generally in the centre of the containment. The structure suitably comprises a conduit for the supply of water to each of the inlets, preferably an inlet in each cell. The inlet may comprise one or more nozzles, preferably 2 to 10 nozzles, for example 6 nozzles for a 7m containment and suitably, the number of nozzles is selected according to the size of the containment. The inflow of water through the inlets imparts force to the body of water within the cell and thereby rotates the body of water within that cell. The structure suitably provides an outlet for water and a drain as described herein in each of the cells and may also provide a means of ingress and egress of other materials.

[0034] Preferably, the structure is configured to enable outflow of water from the containment. In a preferred embodiment, the structure comprises a weir enabling outflow of water from each cell. Suitably, the weir is at height such that of the outflowing water in the containment, at least 50%, preferably at least 80%, especially at least 95% of the water is removed from the containment via the weir. The balance of the water is suitably removed from the containment via the drain. Optionally, the structure comprises means of feeding a component to and / or removing a component from the system / , for example oxygen, nutrients and the like. In a preferred embodiment, the outlet comprises a dam to permit flow of water from the cells into the structure comprising the water outlet. In a preferred embodiment, the structure is located centrally in the containment with the cells arranged around the structure such that water may flow from each cell into the structure via a weir.

[0035] Preferably, the plurality of cells are disposed in a close-packed or tessellated arrangement relative to each other. In an alternative embodiment, the plurality of cells are disposed longitudinally.

[0036] In an especially preferred embodiment, the containment comprises 4 cells wherein the cells are arranged such that the cells are in a generally square arrangement. Suitably, each cell’s peripheral wall is generally of constant radius whereby the containment has a generally quatrefoil shape.

[0037] Suitably, the inlet for each cell is located so as to enable rotation of the body of water in that cell at a rate and direction substantially independently of the rate and direction of the body of water in the other cells. Suitably, the inlet comprises a plurality of nozzles or other means defining an aperture to allow passage of water therethrough into the cell, for example slots.

[0038] Suitably, less than 10%, preferably less than 5%, more preferably less than 1%, particularly not more than 0.2% and, especially minimal mixing occurs between the body of water within one cell with that of an adjacent cell, the percentage being based on the volume of water within one cell. For example, in a containment of 35 to 40m diameter comprising four cells arranged in a square, with the cells being generally circular or of regular polygon shape such that the cells are of the order of 17.5 to 20m diameter and approximately 5m deep, the fluid pathways between adjacent cells and the rate of rotation of the body of water in the cells is such that suitably less than 0.5% mixing occurs, for example less than 2000 litres per minute of water mixes between adjacent cells with a cell volume of 2 million litres.

[0039] The water within a cell suitably remains substantially within that cell and is rotatable in the opposite direction to the body of water in an adjacent cell. The residence time of a body of water in a cell is influenced by the size of the cell. Suitably, for a cell of 2 to 4m diameter or maximum dimension of 4 to 8m the residence time of the body of water in the cell is of the order of 12 to 20 minutes, larger cells, for example a cell of 12 to 20m diameter may have a residence time of 30 to 60 mins. For even larger cells, greater than 20m diameter, 30 to 40m, a residence time of the order of 80 to120 minutes may be optimal. The maximum swim speed suitable for the organisms being farmed will determine the maximum rate of rotation and inflow of water which determines the residence time for a given tank size and optimal swim-speed. These factors are suitably selected having regard to the type of organisms being farmed, the stocking density of the organisms, the size of the fish and their optimal swim speed to ensure appropriate fish welfare and quality. Where the aquaculture system is employed for farming crustaceans, the swim-speed may be a less significant factor than when farming fish, allowing larger containment sizes, for example a containment of 100m diameter may be employed with a residence time of 2 to 3 hours.

[0040] The containment may also comprise a water outlet for egress of water from multiple cells, for example in the form of a central outlet with a weir such that water is removed from the containment at or near the surface of the water rather than at or near the floor of the containment. Suitably, the cells are configured in an arrangement to enable the water outlet to receive water from at least two and preferably all the cells at a location adjacent to two or more cells. The water outlet may be located at a boundary of two or more cells. Suitably, the cells and water outlet are configured such that the water outlet is generally centrally located between the plurality of cells.

[0041] The terms “tank” and “containment” are employed interchangeably herein to mean the same thing.

[0042] The aquaculture system and method of the invention may be employed as a recirculating system, a flow-through system and as a partial flow-through system. In a recirculating system and a partial flow-through system, a treated aqueous stream is suitably delivered to the containment.

[0043] In a recirculating system, the body of water is constantly recycled within the system which is generally closed, although excess water may be removed from the system or water from outside the system be fed to the system as required; suitably such additional water is less than 10% of the volume of water in the containment, preferably less than 5% and especially less than 1% by volume per day. An aquaculture system according to the invention suitably comprises a conduit for recirculating water from the at least one outlet and drain to the at least one inlet. Water which is recirculated in the system of the invention is suitably treated for example to remove waste, to replenish with oxygen, nutrients or the like, or subjected to disinfection such as UV irradiation and ozone disinfection.

[0044] In a flow-through system according to the invention, the system is suitably adapted to be located within a natural body of water, for example the sea or a lake, in which water inflow from the surrounding external body of water and outflow to the body of water is pumped under controlled conditions. Water is received from an external body of water, resides within the aquaculture system for a period of time and then discharged from the system back into the external body of water, preferably the majority of solids are captured and removed for disposal via a drain as defined herein.

[0045] In one embodiment of a flow-through system according to the invention, where the containment is land based it may comprise at least in part a filter enabling passage of water between the volume contained by the containment, and the external body of water. The filter may act as the inlet for water from the external body into the containment and also act as the outlet for water from the containment to the external body of water. A drain as described herein is suitably provided to allow managed removal of solids material, mortalities or other waste from the aquaculture system so as to reduce and, preferably avoid significant deposits of solid material into the external body of water.

[0046] In a further aspect, the invention provides a method of farming an aquatic organisms in an aquaculture system comprising: i) providing an aquaculture system for farming aquatic organisms, comprising a containment comprising a side wall and a floor defining a containment zone for retaining a body of water to provide habitat for the aquatic organisms, at least one inlet for receiving water into the containment, at least one drain defining a drain zone located in the floor of the containment for removing solid waste from the aquatic organisms, the drain comprising an assembly comprising an orifice adapted to, in use, selectively allow passage of larger solids from the containment zone into the drain zone; ii) rotating the body of water in the containment in a horizontal plane at a pre-determined angular velocity suitable for the aquatic organisms; iii) providing feed for the aquatic organisms; iv) removing small waste from the containment through the screen; and v) periodically and selectively removing large waste through the orifice of the assembly.

[0047] The invention provides an aquaculture system according to the invention wherein the containment has one and preferably two orthogonal dimensions of at least 1m, preferably at least 5m, more preferably at least 7m. The containment is suitably not more than about 75m maximum dimension, preferably not more than about 50 to 60m. Preferably, the containment has a minimum dimension from 3.5m to 20m, for example 7m and 40m. The system and method of the invention suitably enable the flow rate of water through the at least one inlet to be controlled such that the velocity of the rotatable water is from 1 to 3, preferably 1.5 to 2.5 and more preferably 1.8 to 2, times the body length of the aquatic organisms per second being cultured with the containment.

[0048] The invention is illustrated below with reference to the accompanying drawings in which:

[0049] Figure 1 shows a side elevation with part cross-sectional view (of the containment) of a drain of an aquaculture system according to the invention;

[0050] Figure 2A shows a side elevation with part cross-sectional view (of the containment) of a different drain of an aquaculture system according to the invention having a movable sleeve;

[0051] Figure 2B shows a side elevation of the drain of the aquaculture system as shown in Figure 2A;

[0052] Figures 3A and 3B shows a side elevation with part cross-sectional view (of the containment) of a different drain of an aquaculture system according to the invention having a movable trap door; and

[0053] Figure 4 shows a side elevation with part cross-sectional view (of the containment) of a different drain of an aquaculture system according to the invention having a movable trap door.

[0054] Figure 1 shows a drain (1) employed in an aquaculture system according to the present invention. The drain (1) is located in the floor (2) of the containment zone which is defined by the floor (2) and a side wall(s) (not shown), upstanding from the floor (2). Suitably, the drain (1) is located in the centre of the containment zone and the floor (2) slopes towards the drain (1) from the sidewalls of the containment zone such that solids are urged towards the drain by gravity as the body of water in the containment zone is rotated. The drain comprises an assembly (3) which allows for selective removal of larger solids, for example dead organisms, from the containment zone. The containment zone and the drain zone are separated by a drain mouth (6). The drain mouth suitably has a drain cover (5a) which may be solid or may be a screen, mesh or filter to allow water flow from the containment zone into the drain zone together with small solids such as faeces and uneaten food. The drain zone (4) may comprise an outlet (not shown) to allow small solids and water to be continuously removed from the drain zone, thereby aiding maintenance of good water quality by removing unwanted small solids and maintaining a healthy environment for the aquatic organisms in the containment zone. Water removed via the drain zone may be treated to remove undesirable components and recycled into the containment zone, optionally with the addition of desirable components such as food and oxygen.

[0055] Larger solids and water pass into an outlet conduit (7) via an orifice (8a) which, in use is in communication with the containment zone such that water and larger solids in the containment zone pass through the orifice into the outlet conduit (7) and are removed from the system for suitable disposal. Th outlet conduit is movable in a vertical direction indicated by the arrow A such that the orifice (8a) may be brought into communication with the containment zone as shown or, by being moved in the direction A may be lowered to a position where the orifice is in the position indicated by dashed lines (8b), whereby larger solids may not enter the orifice and where the orifice is not able to receive larger solids from the containment zone. The orifice is effectively “closed" as regards receiving larger solids when located at 8b. The outlet conduit (7) may then be raised to a position where the orifice (8a) is above the drain mouth (3) and in direct communication with the containment zone and able to receive larger solids. The outlet conduit (7) may be moved or actuated by any suitable system or means, preferably, hydraulically. Movement of the conduit (7) may be controlled electronically or y a computer system and be activated on a periodic basis with a timer or upon activation by another parameter, for example the build-up of solid material in the containment zone at the drain.

[0056] The invention provides two mechanisms for the removal of water and solids from the containment zone; one for removal of water for treatment and recycling which may contain smaller solids and one for removal of larger solids which thereby do not need to be treated in the recycling / treatment system. In this way, larger solids may be removed from the aquaculture system without disrupting management of the body of water passing through the drain and which is suitable for and intended to be recycled.

[0057] Figure 2A and 2B show an alternative embodiment of a drain in the aquaculture system of the invention. In this embodiment, the outlet conduit (7) is not movable and the orifice (8) is selectively opened or closed by means of a movable sleeve (9). The movable sleeve may overlie the orifice (8) as shown in Figure 2A whereby the orifice is not able to remove solids from the containment zone and, as desired, be moved along the conduit (7) so as to expose the orifice (8) whereby, larger solids may then pass through the orifice (8) and be removed via conduit (7). The sleeve (9) may be controlled by any suitable means for example manually and electronically, and may be activated by any suitable means, for example hydraulically. Figures 3A and 3B show another embodiment of the drain employed in an aquaculture system according to the invention. The drain mouth (3) is covered by drain cover (5b) in Figure 3A with an orifice (8), shown in Figure 3B being closed by plug (10). Larger solids are not able to pass through the orifice due to this being closed by plug (10) in Figure 3A. Water and smaller solids may pass into the drain zone (4) from the containment zone through the drain cover (5b) and pass out of the drain zone (4) into a recycle outlet (11 , 13) for the smaller solids to be removed and the water treated as appropriate, optionally to be recycled into the containment zone. A large solids conduit (14) is provided for removal of large solids and is closed by plug (12) while the orifice (8) is closed by plug (10).

[0058] When large solids are to be removed from the containment zone, recycle conduit (13) is closed by plug (10) moving from the orifice (8) to close the mouth (11) of the recycle conduit (11). Alternatively, a separate plug may be used to close mouth (11), large solid conduit (14) is opened by opening plug (12) and the orifice (8) is then opened as shown in Figure 3B. This creates a fluid pathway from the containment zone via the orifice (8) into the drain zone (4) and the large solid conduit (14), thereby allowing larger solids to be removed from the containment zone. Upon removal of the large solids aggregating at the drain mouth, the orifice may be closed, large solid conduit may be closed and the recycle conduit opened thereby creating a fluid pathway for water and smaller solids from the containment zone, through the drain cover (5b) into the drain zone (4) and into the recycle conduit (13).

[0059] Either or both plug (10) and plug (12) and, if employed a further plug for mouth (11) may be pivotally or hingedly mounted for movement between their respective closed and open positions.

[0060] Figure 4 shows another embodiment of a drain in an aquaculture system of the invention. The orifice (8) is located in the drain cover and closed by a trap door and is openable by raising the trap door into the containment zone into an open configuration, as shown. The trap door may be lowered to close the orifice (8) in the direction shown by the arrow. The large solids pass through outlet conduit (7). When the trapdoor is closed, smaller solids and water may pass through the conduit (7). As desired, alternative pathways or switching may be employed downstream to divert flows with larger solids in one direction and flows with smaller solids and with water suitable for recycling in another direction as desired.

Claims

AMENDED CLAIMS received by the International Bureau on 27 January 2025 (27.01.2025)1. An aquaculture system for supporting aquatic organisms comprising: a containment comprising a side wall and a floor defining a containment zone for retaining a body of water to provide habitat for the aquatic organisms; at least one inlet for receiving water into the containment; at least one drain defining a drain zone located in the floor of the containment for removing solid waste from the aquatic organisms, the drain comprising an assembly comprising an orifice adapted to, in use, selectively allow passage of larger solids from the containment zone into the drain zone wherein the assembly comprises: i) a conduit having the said orifice therein and which is selectively open or closed or where the conduit is movable such that the orifice may be moved between the containment zone and able to receive larger solids and the drain zone where the orifice is not accessible to larger solids; and / or ii) a barrier which is adapted to close the said orifice in a closed configuration the barrier cover being moveable between an open position and a closed position to respectively open and close the orifice.

2. An aquaculture system according to claim 1 wherein the assembly comprises a conduit which is located at least in part in the drain zone and in fluid communication with the containment zone and the orifice is located so as to be in fluid communication with the containment zone.

3. An aquaculture system according to claim 2 wherein the assembly comprises a barrier for the orifice, the barrier cover being moveable between an open position and a closed position to respectively open and close the orifice.

4. An aquaculture system according to claim 3 wherein the barrier comprises: i. a sleeve adapted to be moveable along the conduit to selectively open and close the orifice; ii. a plug adapted to be movable into the orifice to close it and away from the orifice to open it; or iii. a trap door adapted to be movable into the orifice to close it and away from the orifice to open it.AMENDED SHEET (ARTICLE 19)5. An aquaculture system according to any one of claims 3 or 4 wherein the assembly comprises resilient means to urge the barrier into the closed position.

6. An aquaculture system according to claim 5 wherein the resilient means comprises a spring or a pneumatic ram.

7. An aquaculture system according to any one of claims 3 to 6 comprising remote means to selectively activate the barrier to move between the closed position and the open position.

8. An aquaculture system according to any one of the preceding claims wherein the conduit is located in the drain zone and is selectively movable to a position such that part of the conduit comprising the orifice is located in the containment zone and part of the conduit is located in the drain zone.

9. An aquaculture system according to any one of the preceding claims wherein the containment is circular or polygonal such that the body of water is rotatable in the containment.

10. An aquaculture system according to any one of the preceding claims comprising means to rotate the body of water in the containment.

11. An aquaculture system according to any one of the preceding claims wherein the drain is located at or near the centre of the containment.

12. An aquaculture system according to any one of the preceding claims comprising a screen or a filter separating the containment zone and the drain zone to enable continuous egress of water and small solids from the containment zone into the drain zone through the filter.

13. An aquaculture system according to claim 12 wherein the wherein the filter comprises a grid or mesh filter.

14. An aquaculture system according to claim 12 or claim 13 wherein the screen comprises apertures sized to permit passage of solids having a maximum dimension of 100mm.AMENDED SHEET (ARTICLE 19)15. An aquaculture system according to any one of the preceding claims wherein the containment comprises a plurality of cells defined within the containment, each cell being configured to hold a body of water which is rotatable within the cell, each cell being in fluid communication with at least one other adjacent cell and each cell comprises a drain located in the centre of the cell.

16. An aquaculture system according to claim 15 wherein the containment comprises at least 3 cells.

17. An aquaculture system according to any one of claims 15 and 16 wherein each cell is defined by a portion of the containment wall, two internal walls extending from the containment wall towards the inner area of the containment, and a further wall which extends to the two internal walls with a space between the further wall and the internal walls.

18. An aquaculture system according to claim 17 wherein the further wall for each cell is provided by a structure located generally in the centre of the containment.

19. An aquaculture system according to claim 18 wherein the structure comprises a water outlet.

20. An aquaculture system according to claim 18 or claim 19 wherein the structure comprises a weir for the removal of water from each cell.

21. An aquaculture system according to claim 20 wherein the weir comprises a dam to permit flow of water from the cells into the structure.

22. An aquaculture system according to any one of claims 15 to 21 wherein the plurality of cells are disposed in a close-packed array or tessellated arrangement to each other.

23. An aquaculture system according to any one of claims 15 to 22 wherein the plurality of cells are disposed longitudinally.AMENDED SHEET (ARTICLE 19)24. An aquaculture system according to any one of claims 15 to 23 comprising 4 cells wherein the cells are arranged such that the cells are in a generally square arrangement.

25. An aquaculture system according to any one of claims 15 to 24 wherein each cell comprises a drain as defined in claim 1.

26. A method of farming an aquatic organisms in an aquaculture system according to any one of the preceding claims comprising: a. providing an aquaculture system for farming aquatic organisms, comprising a containment comprising a side wall and a floor defining a containment zone for retaining a body of water to provide habitat for the aquatic organisms, at least one inlet for receiving water into the containment, at least one drain defining a drain zone located in the floor of the containment for removing solid waste from the aquatic organisms, the drain comprising an assembly comprising a selectively openable orifice adapted to, in use, selectively allow passage of larger solids from the containment zone into the drain zone ; b. rotating the body of water in the containment in a horizontal plane at a predetermined angular velocity suitable for the aquatic organisms; c. providing feed for the aquatic organisms; d. removing small waste from the containment through the screen; and e. periodically and selectively removing large waste through the orifice of the assembly.AMENDED SHEET (ARTICLE 19)

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