NO347024B1

NO347024B1 - A fish farming facility comprising a water outlet cleaning device

Info

Publication number: NO347024B1
Application number: NO20211093A
Authority: NO
Inventors: Alf Reidar Sandstad
Original assignee: Seafarming Systems As
Priority date: 2020-09-10
Filing date: 2021-09-10
Publication date: 2023-04-17
Also published as: NO20211093A1; WO2022055361A1

Description

A FISH FARMING FACILITY COMPRISING A WATER OUTLET CLEANING DEVICE

The present invention relates to a fish farming facility comprising a floating fish pen. More specifically, the invention relates to a semi-closed or a closed fish pen forming an enclosure for fish. The enclosure has a defined water inlet and a defined water outlet. Even more specifically, the invention relates to a collection means for particulate matter located at the water outlet. The collection means retains the particulate matter inside the enclosure, and the particulate matter is removed by a cleaning device which guide the collected particulate matter to a surface for further treatment.

BACKGROUND

Fish farming or pisciculture involves raising fish commercially in enclosures for food. Floating fish farming facilities are well known, and many different types exist such as e.g. floating net pens. The net pens may be anchored to a sea bottom. Floating fish farming facilities may typically comprise an enclosure for fish that is open or exposed to air at an upper portion. The sidewalls and base of the enclosure may be water permeable in order to allow water to flow into and out of the enclosure, while preventing the farmed fish from escaping. Sidewalls and base made of a net are examples of water permeable sidewalls and base. Further, the enclosure may be supported by a floating collar to maintain the enclosure in the body of water, and to support the sidewalls above the surface of the water to form a so-called jump net, if the upper portion is open.

Water currents, such as tidal currents, flow through net pens from one side to the opposite side and basically in a horizontal direction when sidewalls and base are formed of nets. Such net pens have not a defined inlet and outlet. The direction of the flow of water changes with the direction of the water current. The fish inside the net pen need oxygen and oxygen is supplied by the water. Therefore, it is important that there is a sufficient water exchange within the net pen. Fouling of the net pen reduces the flow of water, and cleaning of the nets to remove fouling is necessary to maintain the water flow.

In a traditional net pen, there is no collection of faeces, uneaten feed particles and other debris such as loosened fouling. This material is often named sludge. Hereafter this material will be collectively termed as particulate matter. Particulate matter is sinking and at the same time transported sideways with the water current and dispersed in the recipient when the water current is strong enough. Some of the particulate matter may settle at a seabed below the net pen. Accumulated particulate matter may release toxic gases such as H2S and deteriorate a water column above the particulate matter. This may impact the fish within the net pen in the water column. Therefore, net pens are located at sites with sufficient water current to avoid sediments of particulate matter below the net pen.

Floating fish farming facilities may be located in fjords and close to the shore, or out at sea. Large scale fish farming facilities out at sea comprise flexible enclosures that are water permeable to reduce cost and impacts from waves. Floating fish farming facilities located closer to shore may advantageously comprise a water-tight sidewall and/or base. The sidewall and/or base may be made of a form-stable, stiff or rigid material or of a flexible material. Such a configuration may reduce inflow of harmful organisms such as toxic algae and sea lice into the enclosure. However, such a configuration also reduces the natural flow of water through the pen. To compensate for the reduced natural flow a means for forcing a water flow through the pen must be applied. A semi closed enclosure is an enclosure where the water inside the enclosure is generally not in direct contact with the water outside the enclosure, but a forced flow of water through the enclosure may be controlled through dedicated inlets and outlets, in order to provide a sufficient water exchange rate.

Rearing fish in floating fish pens with a natural water flow is an efficient and inexpensive way of producing fish. However, number of suitable locations or sites with sufficient current are limited. As the production increases, sustainability becomes an issue. In order to deal with problems like sea lice and particulate matter polluting the seabed and water column, the floating fish pens are equipped with water-tight walls and bottoms. When the fish pens are closed, water flow must be forced through the pen. In a floating pen with water-tight walls and bottom it is necessary to pump water from the outside into the pen, through pipes and occasionally out again through pipes. Water is pumped into the pen within pipes from water depths below where the sea lice naturally occur. Pumping sufficient water through the pen to compensate for the natural flow of water through an open net pen is difficult and expensive. Typically, less water is pumped and compensated with addition of oxygen in order to maintain an acceptable oxygen level. Such systems may also have means for treating the inlet water and outlet water within the pipes. In such fish pens the water exchange rate is low enough to remove particulate matter by sedimentation. Particulate matter sinks down in the water column inside the pen to the bottom where it may accumulate, typically in a sink, and can be collected and pumped out of the pen.

For onshore fish raising plants there are solutions for collecting particulate matter based on different types of filtration technologies. However, these are not suitable for floating fish farming facilities, mainly due to cost and limited capacity. Due to high energy costs of pumping water, land-based plants have lower replacement rate for water and rely more heavily on oxygenation and advanced water treatment solutions.

It is an aim to utilise the advantage of a floating fish pen. More specifically, the aim is to have sufficient water exchange to avoid oxygenation of the water, to avoid sea lice infestation, and to collect particulate matter to reduce an impact to the recipient. The large volume of water needed to avoid oxygenation in a semi-closed or closed pen, creates a water circulation that is too intense for sedimentation to occur. Collection of particulate matter in outlet pipes with filters, is difficult if not possible. The speed of the waterflow through the pipes, passing through the filter, is too high to preserve the particulate matter. Rather it will be crushed and impossible to collect. The pumps must overcome the added friction caused by the filter in the pipes, and hence energy usage and cost are increased. It is therefore a need for a system that allow large amounts of water to flow through the pen, which at the same time allows for efficient collection of particulate mater. Documents useful for understanding the field of technology include WO 2006/004415 A1 (corresponding to Norwegian patent application no.20042778), which describes a container for location in the sea for collection of fluids, masses or mixtures of objects and fluids, with a specific weight which is not substantially different from seawater, with a cylindrical shape and arranged for location with the longitudinal axis in vertical direction, and where its sidewalls are assembled of sheet elements which are joined along their side edges forming a shell construction.

EP 3442330 A4 (corresponding to Norwegian patent application no. 20172017) describes a floating fish farming plant including an enclosure supported by a buoyant body which is configured for floating in a body of water. The farming plant further includes a lifting portion arranged between the buoyant body and the enclosure and configured for moving the enclosure between a position at the level of, or below, the buoyant body and a position in which at least a portion of the enclosure is above the buoyant body.

WO 2017/155414 describes a fish pen where a net forms the upper wall. The upper wall is surrounded by a lice skirt. The pen is provided with flow setters, each flow setter comprising a vertical supply tube for water. The inlet of the tube is located beneath the lice skirt and the outlet is horizontally directed at the surface of the pen. Thereby the upper body of water within the pen is set in rotation. A collection funnel is positioned underneath the net and forms the bottom of the pen. The collection funnel may be raised in the water column until the funnel meets the lice skirt.

NO 332955 B1 describes a hatch for adjustment of a water flow through a watertight wall in a fully closed fish pen or in a pen with watertight walls but with an open bottom.

There is a need for an improved fish farming facility to reduce or eliminate the abovementioned disadvantages of known techniques. It is an objective of the present invention to achieve this and to provide further advantages over the state of the art.

SUMMARY

It is an object of the present invention to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem.

To satisfy the need for large amounts of water to flow through the fish pen as well as to collect particulate matter, the inventor has found that the outlet needs to cover a sufficient wide area for the large amounts of water to flow slowly enough through the outlet and correspondingly have a low enough drop in pressure. Thereby the particulate matter is not crushed on a filter that covers the wide opening. In addition, a device must carefully collect the particulate matter that is trapped at the filter, avoiding crushing it and avoiding decomposition before the particulate matter can be stabilised through drying at a suitable location. Collecting and removing the particulate matter and cleaning the filter must also be done frequently to avoid pathogens in the pen and to maintain the outlet flow.

Fish pens satisfying the requirement of large enough water flow and a sufficient outlet area is typically referred to as semi-closed fish pens. Fish pens that have inlet and outlet through piping is sometimes referred to as closed pens, whereas some skilled persons may still classify them as semi-closed because water is still flowing in and out of the pen. The same skilled persons may only accept to call RAS (Recirculating Aquaculture Systems) for a closed fish pen.

According to a first aspect, there is provided a floating fish farming facility comprising an enclosure for fish comprising a base and a sidewall. The enclosure forms an inside and an outside, and the sidewall comprises a water impermeable structure. The floating fish farm further comprising:

- a water inlet for a flow of inlet water into the enclosure;

- a water outlet for the flow of outlet water out from the enclosure; and

- at least one means for generating the flows of water through the enclosure from the water inlet to the water outlet.

The water outlet is provided with an outlet filter for collecting a particulate matter within the enclosure. The outlet filter may be arranged on the inside of the enclosure.

According to an embodiment of the invention, the means for generating the flows of water may comprise at least one flow generator. The flow generator may be an ejector, a water jet, a propeller, a thruster. In one embodiment the means for generating the flows of water may be the biomass of the fish within the enclosure.

According to an embodiment of the invention, the sidewall may comprise the water inlet for the flow of water into the enclosure. According to an alternative embodiment of the invention, the base may comprise the water inlet for the flow of water into the enclosure.

According to an embodiment of the invention, the base may comprise the water outlet for the flow of outlet water out of the enclosure. According to an alternative embodiment of the invention the water outlet may encircle the circumference of the enclosure. According to an alternative embodiment of the invention the water outlet may be provided in a lower section of the sidewall. According to an embodiment of the invention, the water outlet may be provided adjacent to the base.

According to an embodiment of the invention, a portion of the base may comprise a water-tight structure. In this embodiment the inlet may cover only a part of the base. The inlet may be positioned at the center of the base. In an alternative embodiment the inlet may be positioned at a circumference of the base. The inlet at the center of the base may be provided with a circular outer shape. According to a further variant of this embodiment, the outlet may cover only a part of the base. The outlet may be positioned at the center of the base. In an alternative embodiment the outlet may be positioned at a circumference of the base.

According to an embodiment of the invention, the farming facility may comprise an outlet cleaning device. The outlet cleaning device may be movably connected to an upper portion of the sidewall. According to an embodiment of the invention, the outlet cleaning device may comprise a suction device for removing particulate matter such as dirt and waste. According to an embodiment of the invention, the outlet cleaning device may comprise a brush for loosening particulate matter such as dirt and waste.

According to an embodiment of the invention, the water outlet may be provided with a support structure and the outlet filter is arranged upstream to the support structure. The support structure may be net. The support structure may be a grid. According to an embodiment of the invention, the outlet filter is strong enough to span the outlet without support.

According to an embodiment of the invention, the sidewall may comprise a stiff structure. According to an embodiment of the invention, the base may comprise a stiff structure.

According to an embodiment of the invention, the water inlet may be provided with an inlet filter for preventing lice from entering the enclosure.

While the invention describes a distinct water inlet and a distinct water outlet, this must be understood to mean mainly an inlet and an outlet. Some water may enter the enclosure through an area defined as a water outlet and some water may exit the pen through an area defined as a water inlet without deviating from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein:

Fig.1 shows a perspective view of an embodiment of a floating fish farming facility comprising an enclosure for fish, flow generators and an outlet cleaning device;

Fig.2 shows a sectional side view the floating fish farming facility; and

Figs. 3-5 show alternative enclosures in a floating fish farming facility.

The present invention will now be described with reference to the accompanying drawings, in which preferred example embodiments of the invention are shown. The invention may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the invention to the skilled person.

Referring to figures 1 and 2, a floating fish farming facility 1 is shown. The floating fish farming facility 1 is configured for floating in a body of water 91. The floating fish farming facility 1 comprises an enclosure 2 for cultivating fish. The enclosure 2 comprises a base 3, a sidewall 4 and an upper portion 5. The sidewall 4 is shown cylindrical in figure 1. The enclosure 2 is connected to a floating collar 6 to maintain the enclosure 2 floating in the body of water 91. The enclosure 2 may additionally be equipped with further buoyancy means. The enclosure 2 defines an inside 7 and an outside 8. The inside 7 is the side of the enclosure 2 where the fish is cultivated, the outside 8 is the side exposed to the body of water 91 the floating fish farming facility 1 is arranged in.

The floating collar 6 is at least partly encircling the enclosure 2 in a horizontal plane. The floating collar 6 may be a homogenous buoyant structure encircling the enclosure 2, or it may be several buoyant elements connected together around the enclosure 2. The floating collar 6 is preferably configured to move somewhat relative to the enclosure 2, such that impacts from waves and tidal forces are not directly transferred from the floating collar 6 to the enclosure 2. The floating collar 6 is configured for floating on the surface 90 of the body of water 91, and as the enclosure 2 is connected to the floating collar 6, it keeps the enclosure 2 positioned in the body of water 91. The floating collar 6 or the enclosure 2 may advantageously be anchored to a sea bottom (not shown). A floating collar 6 is known in the art of floating fish farming facilities and is not described in further detail.

The enclosure 2 is preferably open towards the atmosphere at the upper portion 5, and the enclosure 2 may as such be a closed or semi-closed structure. The enclosure 2 may comprise stiff and water-tight structures. The enclosure 2 may preferably be a steel tank or a tank made from generally stiff and water-tight structures. However, the enclosure 2 may also comprise flexible and water-tight structures, or water permeable structures. A stiff structure is a structure that is generally stiff in nature, but that may flex somewhat due to the size or span of sections. An enclosure 2 comprising a stiff and water-tight base 3 and sidewall 4 may in one embodiment be formed from stiff and water-tight materials such as glass fibre, sheet metal, etc. having an inside 7 and an outside 8. An enclosure 2 comprising a stiff and water-tight base 3 and sidewall 4 may in another embodiment comprise an outside 8 comprising e.g. stiff bars or a stiff grid and an inside 7 comprising a water-tight membrane or fabric.

The base 3 may in one embodiment in a portion comprise a stiff and water-tight structure. The stiff and water-tight structure may be steel, glass-fibre, etc. The outer portion of the base 3 may preferably comprise a stiff and water-tight portion, such as a brim along the circumference of the base 3.

The base 3 comprises a water inlet 9 for an inlet flow of water 990 into the enclosure 2. The water inlet 9 may be arranged in the center of the base 3 in order to provide a homogenous flow of inlet water 990 into the enclosure 2. The inlet 9 may comprise a seine or equivalent barrier in order to prevent fish from inside the enclosure 2 from escaping through the inlet 9.

In another embodiment, the base 3 may be a generally flexible and water-tight structure comprising a water inlet 9 as described above. The flexible and water-tight structure may be a water-tight membrane or fabric. The entire base 3 may alternatively also be arranged as a water inlet 9.

The fish farming facility 1 may comprise at least one flow generator 15. Figure 1 discloses two flow generators 15, but the fish farming facility 1 may as such comprise any number of flow generators 15. Preferably, the fish farming facility 1 comprises four flow generators 15. The flow generators 15 are arranged on the inside of the enclosure 2. In the embodiment shown in figures 1 and 2, the flow generators 15 are configured for generating a horizontal, circular water flow 99 inside the enclosure 2. In turn this horizontal circular water flow 99 creates a centrifugal effect causing a negative pressure in the center volume of the enclosure and a positive pressure in the peripheral volume of the enclosure, towards the inside of the wall 4. This combination of negative pressure and positive pressure pumps or move water through the enclosure 2, in through the inlet 9, circulating in the enclosure 2 and out through the outlet 11. The flow generators 15 may preferably be arranged in an upper portion 5 of the enclosure 2. As the thrust of the flow generators 15 may be directed in a generally tangential direction, and at least an upper part of the sidewall 4 comprises a water-tight material, a circular water flow 99 is created inside the enclosure 2. The circular water flow 99 occupies a volume from the surface 90 down to the base 3. Such flow generators 15 may be ejectors, jets, propellers, thrusters, etc. that has the water intake inside the enclosure 2 at the upper portion 5. The flow generators 15 may be arranged on the sidewall 4 and may be connected to the upper portion 5 of the sidewall 4. As the water within the enclosure 2 is circulated horizontally, a negative pressure is created in the center volume of the water column within the enclosure 2. This negative pressure move water in through the water inlet 9 at the base 3.

The enclosure 2 preferably has a height such that the base 3 is arranged at a water depth where lice and other organisms do not naturally occur. The water that is flowed through the water inlet 9 in the base 3 is thus not contaminated with lice and other organisms harmful for the fish inside the enclosure 2. To further reduce the risk of contamination, the water inlet 9 may be provided with an inlet filter 10 for preventing contamination such as lice from entering the enclosure 2. The inlet filter 10 may cover the entire base 3, even if the water inlet 9 only spans a portion of the base 3 and may in an alternative embodiment even cover the sidewall 4. The inlet filter 10 may be a thin membrane, a fabric or a fine meshed net, similar to a water permeable lice barrier.

The sidewall 4 may in one embodiment comprise a stiff and water-tight structure. The stiff and water-tight structure may be steel, glass-fibre, etc. The stiff and water-tight structure may span a portion of the sidewall 4, or it may span the entire sidewall 4. The upper portion of the sidewall 4 may preferably comprise a stiff and water-tight portion.

The sidewall 4 comprises a water outlet 11 for a flow of water out from the enclosure 2. The horizontal, circular flow inside the enclosure 2 thus provides a flow of water in through the inlet 9, circulates the water inside the enclosure 2, and flows it out through the water outlet 11. The water outlet 11 may also overlap or extend to the base 3. There may also be curvature between the sidewall 4 and the base 3 such that there is no clearly defined portion where the sidewall and base meet. Such alternatives are all to be understood as a sidewall 4 comprising a water outlet 11.

The water outlet 11 may encircle the circumference of the enclosure 2 as illustrated in figure 1. The water outlet 11 may encircle the circumference of the enclosure 2 continuously or in sections. The sections may be openings (not shown) spaced apart, at intervals, or other configurations. It is to be understood that a continuous water outlet 11 still implies some sort of connection between the base 3 and the sidewall 4, such that the base 3 is fixed relative to the sidewall 4. Perforations in the sidewall 4 may be such a continuous configuration, or even a complete cutout in the sidewall 4, where a structure (not shown) on the outside 8 of the sidewall 4 and base 3 fixes the base 3 to the sidewall 4. The water outlet 11 may be provided in a lower section of the sidewall 4. A lower section is defined as the lower half of the height of the sidewall 4. The water outlet 11 may preferably be arranged adjacent to the base 3, such that the base 3 meets the water outlet 11, and dirt and waste on the base 3 can efficiently be moved towards the water outlet 11.

In another embodiment, the sidewall 4 may be a generally flexible and water-tight structure comprising the water outlet 11 as described above. The flexible and water-tight structure may be a water-tight membrane or fabric.

The water outlet 11 is provided with an outlet filter 12. Dirt and waste such as uneaten food particles, food dust, feaces, dead fish, etc. is accumulated within the enclosure 2. Because of the water flow inside the enclosure 2, dirt and waste will accumulate at the water outlet 11 where the water flows out of the enclosure 2. The dirt and waste are accumulated on or at the outlet filter 12. The outlet filter 12 prevents release of dirt and waste to the surrounding water. The outlet filter 12 may be provided on the inside 7 of the enclosure 2. The outlet filter 12 may form the barrier or sidewall at the outlet 11. The outlet filter 12 may span more than just the water outlet 11 and may in an alternative embodiment cover the inside 7 of the sidewall 4, and even the base 3. If the sidewall 4 is a stiff structure, the water outlet 11 may preferably be provided with a support structure 110. The support structure 110 may be a net, a grid, or bars to support the outlet filter 12. The outlet filter 12 may be a thin membrane, a fabric, or a fine meshed net, similar to a water permeable lice barrier. The support structure 110 may prevent bulging of the outlet filter 12. The outlet filter 12 preferably forms a flat surface. The outlet filter 12 is accessible for a cleaning device 13 for collecting the particulate matter and for cleaning the outlet filter 12 to ensure sufficient water flow through the outlet 11. The outlet filter 12 may form a part of a rotational body with a central axis, i.e the circumference of a cylinder or a plane circle, so that the cleaning device 13 can rotate around the central axis.

The floating fish farming facility 1 comprises an outlet cleaning device 13. The outlet cleaning device 13 may be movably connected to the sidewall 4 and can move along the sidewall 4 and clean the outlet filter 12 for accumulated particulate matter 98, as illustrated in the figures 1 and 2. The outlet cleaning device 13 may alternatively be connected to a rotating frame or a pole (not shown) connected to the center of the enclosure 2. The outlet cleaning device 13 may in a first embodiment move on wheels along a track on the upper portion 5 of the sidewall 4. The outlet cleaning device 13 may be connected by means of bearings along a rod spanning the circumference of the upper portion 5, or by any other means known in the art of controlling a mechanical device along a guide. The outlet cleaning device 13 should preferably be able to move around the entire circumference of the enclosure 2. The outlet cleaning device 13 may be automatically activated and controlled. The outlet cleaning device 13 may in the first embodiment comprise a generally stiff structure that arranges the outlet cleaning device 13 next to the outlet filter 12. Such an outlet cleaning device 13 may be configured for collecting particulate matter and cleaning the outlet filter 12 of a generally stiff sidewall 4.

The outlet cleaning device 13 may in a second embodiment be connected flexible to the sidewall 4. The outlet cleaning device 13 may in the second embodiment also be configured to move around the entire circumference of the enclosure 2, and the outlet cleaning device 13 may be automatically activated and controlled. The outlet cleaning device 13 may in the second embodiment comprise flexible connections that allows the outlet cleaning device 13 to move in a greater radial direction relative to the sidewall 4. The outlet cleaning device 13 of the second embodiment may be suited for collecting particulate matter and cleaning the outlet filter 12 of a flexible sidewall 4. A sidewall 4 comprising a generally flexible structure may move substantially in a radial direction compared to a sidewall comprising a generally stiff structure. The outlet cleaning device 13 of the second embodiment may thus be configured for collecting particulate matter and cleaning the outlet filter 12 of a generally flexible sidewall 4.

The outlet cleaning device 13 may comprise a suction device 14. The suction device 14 may be connected to an end of a hose or tube provided with a negative, such that particulate matter 98 e.g. dirt and waste, is sucked into the suction device 14. The hose of the suction device 14 may be arranged along the length of the outlet cleaning device 13, such that the particulate matter sucked into the suction device 14 is transported from the outlet filter 12 to e.g. a separate tank (not shown) on the fish farming facility 1, or elsewhere. The cleaning device 13 may also comprise a brush, for loosening dirt and waste from the outlet filter 12. The suction device 14 may alternatively or additionally comprise a scraper (not shown) or similar flexible element, for removal of dirt and waste from the outlet filter 12. The cleaning device 13 may also clean the inside 7 of the enclosure 2.

A second embodiment is shown schematically in figure 3. The enclosure 2 comprises a base 3, a sidewall 4 and an upper portion 5. The enclosure 2 is connected to a floating collar 6 to maintain the enclosure 2 floating in the body of water 91. The enclosure 2 may additionally be equipped with further buoyancy means. The enclosure 2 defines an inside 7 and an outside 8.

The floating collar 6 is configured for floating on the water surface 90 of the body of water 91, and as the enclosure 2 is connected to the floating collar 6, it keeps the enclosure 2 positioned in the body of water 91. The sidewall 4 and the base 3 may be formed of the same materials as described for the embodiment shown in figures 1 and 2. The sidewall 4 may protrude above the water surface 90 to form a jump wall.

The enclosure 2 is divided into two compartments by a water-tight inner wall 41. The inner wall 41 is continuous and forms a closed wall. The inner wall 41 may be circular. The inner wall 41 forms an upper portion 40 and a lower portion 49. The upper portion 40 of the inner wall 41 is positioned below the water surface 90 within the enclosure 2. A flexible or rigid net 43 or similar is fastened to the upper portion 40 and extends upwards to or above the water surface 90. The net 43 may be kept in an upright position from the inner wall to the water surface 90 by a buoyancy body 60. The net 43 may protrude above the water surface 90 to form a jump wall.

In another embodiment (not shown) the inner water-tight wall 41 is independent of a net placed inside the inner wall 41 creating a full enclosure with walls and bottom. The net may be kept in an upright position by a buoyancy body. The net and buoyancy body may be similar to a traditional net pen. The bottom of the net may be at the same depth as the bottom of the inner wall 49. The inner water-tight wall 41 may be rigid or flexible. A flexible wall may be kept outstretched and vertical by different means.

A horizontal net (not shown) may in another embodiment be fastened at the top of the inner water-tight wall 40, keeping the fish out of the inner volume created by the inner water-tight wall 41, the top of the wall 40 and the bottom of the wall 49. The fish may be stocked in the volume in the annulus 45 and the volume in the upper portion 5 of the enclosure.

The lower portion 49 is provided with a water inlet 9 for a flow of inlet water 990 into the enclosure 2.

The wall 4 and the inner wall 41 form between them an annulus 45. The inner wall 41 forms an internal passage 46. In this embodiment the fish (not shown) is stocked in the annulus 45. The net 43 blocks the fish from swimming out of the annulus 45 and into the passage 46. A second net 47 or similar, blocks fish or other marine animals from entering the passage 46 from outside the enclosure 2 through the inlet 9.

The enclosure 2 is provided with a water outlet 11 at the base 3. An outlet filter 12 may cover the entire water outlet 11, even if the water outlet 11 only spans a portion of the base 3. In an alternative embodiment the outlet filter 12 even covers parts of the sidewall 4. The water outlet 11 may preferably be provided with a support structure 110. The support structure 110 may be a net, a grid, or bars to support the outlet filter 12. The outlet filter 12 may be a thin membrane, a fabric or a fine meshed net, similar to a water permeable lice barrier.

The enclosure may optionally be provided with a cleaning device 13. The cleaning device may comprise a suction device 14 as described in the embodiment shown in figures 1 and 2. The cleaning device collects particulate matter and cleans the outlet filter 12.

In the embodiment shown in figure 3, the flows of water 990, 99, 999 may be created by flow generators 15 positioned in the upper portion 5 of the enclosure 2. The flow generators create a circular water flow 99 comparable to the embodiment shown in figure 1 in the upper portion 5, and the circular water flow 99 creates a negative pressure in the passage 46 and a positive pressure out towards the inside of the outer wall 4 in the annulus 45. This negative pressure lifts inlet water 990 through the water inlet 9 at the base 3. The flow of water enters the annulus 45 through the net 43 and the outlet water 999 flows out through the outlet 11 at the bottom of the annulus 45. The outlet water 999 is pushed downward by the positive pressure along the sidewall 4 created by the centrifugal effect from rotational water flow 99 created by the flow generators 15. Dirt and waste from the fish in the annulus 45 are collected as particulate matter 98 on the outlet filter 12 within the annulus 45. Thereby the dirt and waste are not dispersed to the recipient.

The fish enclosure 2 is shown in one embodiment in figure 3 and in an alternative embodiment in figure 4. In the alternative embodiment shown in figure 4, the inner wall 41 extends below the base 3. The water inlet 9 is thereby positioned deeper than the water outlet 11, minimising effluent water from the enclosure 2 circulating back into the enclosure 2. In this embodiment the fish has access to a peripheral part of the enclosure 2, i.e. the annulus 45, but not to the passage 46.

In further alternative embodiments (not shown) to the embodiments shown in figures 3 and 4, the water outlet 11 is positioned in the lower portion of the sidewall 4 in a similar manner as described for the embodiment shown in figures 1 and 2. The outlet filter 12 and the cleaning device 13 may also be similar to the embodiment shown in figures 1 and 2. The base of the annulus 45 may comprise a water-tight material. The water-tight material may a rigid material or a flexible material.

The flows of water 990, 99, 999 in the embodiments shown in figures 3 and 4 may be created by several methods, and by a combination of several methods and by a combination of different apparatus. Non-limiting examples are: 1) flow generators creating a circular water flow 99 in the upper portion 5 of the enclosure 2, further creating a flow of inlet water 990 into the enclosure through the inlet 9 and a flow of outlet water 999 out of the enclosure through the outlet 11.2) utilizing a pumping effect of the biomass of fish (not shown) to generate the inlet water flow 990 in through the inlet 9 and the outlet water flow 999 out through the outlet 11, by stocking the fish in the outer annulus 45 and keeping the fish out of the passage 46.3) Pumps, flow generators, ejectors, thrusters or similar placed in a manner in the enclosure 2 in order to generate the desired water flows 990, 999. 4) Any combination of the above.

A third embodiment is shown schematically in figure 5. The enclosure 2 comprises a base 3, a sidewall 4 and an upper portion 5. The enclosure 2 is connected to a floating collar 6 to maintain the enclosure 2 floating in the body of water 91. The enclosure 2 may additionally be equipped with further buoyancy means. The enclosure 2 defines an inside 7 and an outside 8.

The floating collar 6 is configured for floating on the water surface 90 of the body of water 91, and as the enclosure 2 is connected to the floating collar 6, it keeps the enclosure 2 positioned in the body of water 91. The sidewall 4 and the base 3 may be formed of the same materials as described for the embodiment shown in figures 1 and 2.

The enclosure 2 is divided into two compartments by a water-tight inner wall 41. The inner wall 41 is continuous and forms a closed wall. The inner wall 41 may be circular. The inner wall 41 forms an upper portion 40 and a lower portion 49. The upper portion 40 of the inner wall 41 is positioned below the water surface 90 within the enclosure 2. A rigid or flexible net 43 or similar is fastened to the upper portion 40 and extends upwards to above the water surface 90. The net 43 may be kept in an upright position from the inner wall to the water surface 90 by a buoyancy body 60. The net 43 may protrude above the water surface 90 to form a jump wall.

The wall 4 and the inner wall 41 form between them an annulus 45. The inner wall 41 forms an internal rearing volume 48. In this embodiment the fish (not shown) is stocked in the rearing volume 48. The net 43 blocks the fish from swimming out of the rearing volume 48 and into the annulus 45.

In another embodiment (not shown) the inner water-tight wall 41 is independent of a net placed inside the inner wall 41 creating a full enclosure with walls and bottom. The net may be kept in an upright position by a buoyancy body. The net and buoyancy body may be similar to a traditional net pen. The bottom of the net may be next to the bottom of the inner wall 49. The inner water-tight wall 41 may be rigid or flexible. A flexible wall may be kept outstretched and vertical by different means.

A horizontal net (not shown) may in another embodiment be fastened at the top of the inner water-tight wall 40 and the outer wall 4, keeping the fish out of the annulus below the top of the inner wall 41. The fish may be stocked in the rearing volume 48 and the volume in the upper portion 5 of the enclosure.

The annulus 45 forms a water inlet 9 for a flow of inlet water 990 into the enclosure 2 at a lower portion 459 of the annulus 45. A second net 47 or similar, blocks fish or other marine animals from entering the annulus 45 from outside the enclosure 2 through the inlet 9.

The enclosure 2 is provided with a water outlet 11 at the lower portion of 49 of the rearing volume 48. An outlet filter 12 may cover the entire water outlet 11, even if the water outlet 11 only spans a portion of the diameter of the rearing volume 48. In an alternative embodiment the outlet filter 12 even covers parts of the inner wall 41. The water outlet 11 may preferably be provided with a support structure 110. The support structure 110 may be a net, a grid, or bars to support the outlet filter 12. The outlet filter 12 may be a thin membrane, a fabric or a fine meshed net, similar to a water permeable lice barrier.

The enclosure may optionally be provided with a cleaning device 13 for collecting particulate matter and cleaning the outlet filter 12. The cleaning device 13 may comprise a suction device 14 as described in the embodiment shown in figures 1 and 2.

In the embodiment shown in figure 5, the flow of waters 990, 999 may be created by stocking fish in the rearing volume 48. In an alternative embodiment, additional flow generators, pumps, ejectors, or similar (not shown) may be positioned to pump water from the annulus 45 into the rearing volume 48, adding to the flow of water 990, 999 created by the fish. The flow of inlet water 990 enters the rearing volume 48 through the net 43 and flows out the water outlet 11 as outlet water 999 at the bottom of the rearing volume 48. Dirt and waste from the fish in the rearing volume 48 are collected on the outlet filter 12 within the rearing volume 48. Thereby the dirt and waste are not dispersed to the recipient.

In further alternative embodiments (not shown) to the embodiments shown in figure 5, the water inlet 9 is positioned in the lower portion of the sidewall 4. The base of the annulus 45 may comprise a water-tight material. The water-tight material may a rigid material or a flexible material.

The appropriate size of the inlet and outlet area must be determined by the skilled person to achieve sufficient water flow and the appropriate speed of water and corresponding drop in pressure, as the water flows through the outlet filter 12 and deposits the particulate matter 98.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

C l a i m s

1. A floating fish farming facility (1) comprising:

- an enclosure (2) for fish comprising a base (3) and a sidewall (4), the enclosure (2) forming an inside (7) and an outside (8), and the sidewall (4) comprises a water-tight structure;

- a water inlet (9) for a flow of inlet water (990) into the enclosure (2);

- a water outlet (11) for a flow of outlet water (999) out from the enclosure (2); and

- at least one means for generating the flows of water (990, 999) through the enclosure (2) from the water inlet (9) to the water outlet (11),

c h a r a c t e r i z e d i n t h a t

the water outlet (11) is provided with an outlet filter (12) for collecting a particulate matter (98) within the enclosure (2).

2. The floating fish farming facility (1) according to claim 1, wherein the means for generating the flows of water (990, 999) comprises at least one flow generator (15).

3. The floating fish farming facility (1) according to claim 1, wherein the sidewall (4) comprises the water inlet (9) for the flow of inlet water (990) into the enclosure (2).

4. The floating fish farming facility (1) according to claim 1, wherein the base (3) comprises the water inlet (9) for the flow of inlet water (990) into the enclosure (2).

5. The floating fish farming facility (1) according to any one of the preceding claims, wherein the base (3) comprises the water outlet (11) for the flow of outlet water (999) out of the enclosure (2).

6. The floating fish farming facility (1) according to claim 1, wherein the water outlet (11) encircles the circumference of the enclosure (2).

7. The floating fish farming facility (1) according to claim 1, wherein the water outlet (11) is provided in a lower section of the sidewall (4).

8. The floating fish farming facility (1) according to claim 1, wherein the water outlet (11) is provided adjacent to the base (3).

9. The floating fish farming facility (1) according to any one of the preceding claims, wherein a portion of the base (3) comprises a water-tight structure.

10. The floating fish farming facility (1) according to any one of the preceding claims, wherein the floating farming facility (1) comprises an outlet cleaning device (13).

11. The floating fish farming facility (1) according to claim 10, wherein the outlet cleaning device (13) comprises a suction device (14) for removing the particulate matter (98).

12. The floating fish farming facility (1) according to claim 10, wherein the outlet cleaning device (13) comprises a brush for loosening the particulate matter (98).

13. The floating fish farming facility (1) according to any one of the preceding claims, wherein the water outlet (11) is provided with a support structure (110) and the outlet filter (12) is arranged upstream to the support structure (110).

14. The floating fish farming facility (1) according to any one of the preceding claims, wherein the sidewall (4) comprises a stiff structure.

15. The floating fish farming facility (1) according to any one of the preceding claims, wherein the base (3) comprises a stiff structure.

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