An apparatus and system for aquaculture

Abstract

There is provided an apparatus (120) for aquaculture, comprising at least one processor (610) and at least one memory (620) storing instructions that, when executed by the at least one processing core, cause the apparatus at least to receive, from a first sensor (110), information about an oxygen level in at least one tank (160), wherein the at least one tank is for aquaculture, receive, from at least one second sensor (112, 114), information about carbon dioxide and / or pH level in the at least one tank, determine, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank, control, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture and determine, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.

Description

AN APPARATUS AND SYSTEM FOR AQUACULTUREFIELD

[0001] Embodiments of the present disclosure relate in general to an apparatus and a system for aquaculture.BACKGROUND

[0002] Aquaculture, generally referred to as farming of aquatic organisms, such as fish and shellfish, under controlled conditions, is a fast-growing agricultural sector that allows for harvesting seafood for human and animal consumption or for restocking purposes. By means of aquaculture a variety of aquatic species can be produced in a cost-effective manner and with predictable yields regardless of external conditions, such as weather and / or population fluctuations.SUMMARY OF THE DISCLOSURE

[0003] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims.

[0004] According to a first aspect of the present disclosure, there is provided an apparatus for aquaculture, comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to receive, from a first sensor, information about an oxygen level in at least one tank, wherein the at least one tank is for aquaculture, receive, from at least one second sensor, information about carbon dioxide and / or pH level in the at least one tank, determine, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank, control, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture and determine, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.

[0005] According to a second aspect of the present disclosure, there is provided a system comprising a first sensor, at least one second sensor and an apparatus for aquaculture, wherein• the first sensor is configured to transmit information about an oxygen level in at least one tank to the apparatus, the at least one tank being for aquaculture;• the at least one second sensor is configured to transmit information about carbon dioxide and / or pH level in the at least one tank to the apparatus; and• the apparatus is configured to:o determine, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank;o control, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture; ando determine, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 illustrates a first example of a system for aquaculture in accordance with at least some embodiments of the present disclosure;

[0007] FIG. 2 illustrates a second example of a system for aquaculture in accordance with at least some embodiments of the present disclosure;

[0008] FIG. 3 illustrates a third example of a system for aquaculture in accordance with at least some embodiments of the present disclosure;

[0009] FIG. 4 illustrates a fourth example of a system for aquaculture in accordance with at least some embodiments of the present disclosure;

[0010] FIG. 5 illustrates a fifth example of a system for aquaculture in accordance with at least some embodiments of the present disclosure;

[0011] FIG. 6 illustrates an apparatus capable of supporting at least some embodiments of the present disclosure;

[0012] FIG. 7 illustrates a flow graph of a method in accordance with at least some embodiments of the present disclosure.EMBODIMENTS

[0013] Embodiments of the present disclosure are related to an apparatus and a system for aquaculture, such as fish farming. More specifically, embodiments of the present disclosure enable automatic control of water quality, to keep the oxygen, carbon dioxide and pH levels in at least one tank at a desired level, along with water parameters. For example, the carbon dioxide level in the at least one tank may be controlled in order to affect pH, to also control the ammonia / ammonium ratio (NH3 / NH4+) of water. Such benefits may be achieved by using a two-staged process, wherein aeration of the at least one tank is first controlled such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture. After that it may be determined whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.

[0014] Aquatic organisms do not need carbon dioxide dissolved in water, but high levels of carbon dioxide are harmful to them. That is, if only one parameter (carbon dioxide) is considered, then in principle the lower the carbon dioxide level is, the better. But given the overall picture, a slightly elevated concentration of carbon dioxide can be beneficial to aquatic organisms. A slightly elevated concentration of carbon dioxide does not cause side effects by itself yet, but it lowers the pH level and reduces the toxicity of ammonium. The benefit provided by the embodiments of the present disclosure comes specifically from the inhibition of the side effects of ammonium.

[0015] FIG. 1 illustrates a first example of a system for aquaculture in accordance with at least some embodiments of the present disclosure. The system 100 of FIG. 1 comprises a first sensor 110, such as an oxygen (O2) sensor, and at least one second sensor 112 or 114, such as a carbon dioxide (CO2) sensor or pH sensor. The system further comprises an apparatus 120, such as a Programmable Logic Controller, PLC. The apparatus 120 may be configured to receive information for the first sensor 110 and at least one second sensor 112 or 114.

[0016] In some embodiments, the system 100 may further comprise a flow controller 130. The flow controller 130 may be a mass flow controller, volume flow controller, aproportional flow valve or a magnetic valve (i.e., an on-off type magnetic valve). The flow controller 130 may be a motorized valve, which tunes the opening restricting the flow larger or smaller depending on the need. The mass flow controller or the volume flow controller may also measure a weight or volume of the flowing gas, thereby giving the exact oxygen consumption information. The operation of the flow controller 130 may be controlled with information gathered by the oxygen sensor 110. The flow controller 130 controls the oxygen fed to an oxygen dissolving unit, such as a microbubble diffusor, so that the oxygen level can be kept at a desired level continuously, even though there would be changes in the oxygen consumption.

[0017] Alternatively, or in addition, the system 100 may comprise a frequency converter 140. The apparatus 120 may be configured to control the flow controller 130 and / or the frequency converter 140. The system 100 may comprise an air blower 150 and in such a case, the frequency converter 140 may be associated with the air blower 150. That is, the frequency converter 140 may further control the air blower 150, based on control information received from the apparatus 120. The apparatus 120 may be configured to receive information from the sensors 110 - 114 via a communication network and further control the flow controller 130 and the frequency converter 140 via the same, or another communication network.

[0018] In some embodiments, the frequency converter 140 may adjust a frequency of the current coming to an alternating current engine, which may further have an effect to rotations of a motor of the blower 130, and that may further affect to production of air. If the frequency is increased, air production is increased and removal of carbon dioxide becomes more effective (and pH increases and a larger amount of ammonium transforms to NH3 form). And the other way around, if the frequency is decreased, the rotation speed and the air production decrease. Because of that, the carbon dioxide level of the water increases (and pH decreases and a larger amount of ammonia transforms into ionized form NH4+). An alternative way, even though not as energy efficient, would be to strangle the feeding of air with valves.

[0019] The system 100 may further comprise at least one tank 160, which may further comprise water. That is, the at least one tank 160 is a water tank for aquaculture, such as fish farming. However, in some embodiments the system 100 might not comprise the at least one tank 160. That is, the system 100 may for example comprise the first sensor 110, at least oneof the second sensors 112 or 114 and apparatus 120, and the at least one tank may be located outside of the system 100 in such a case. Additionally, in some embodiments, the system 100 may also comprise the flow controller 130 and the frequency converter 140, even if the at least one tank 160 would be located outside of the system 100. If the at least one tank 160 would be located outside of the system 100, the system 100 may be connected to the at least one tank 160 via a communication network.

[0020] The first example system 100 illustrated in FIG. 1 presents a solution for gas exchange and flow control system, wherein removal efficiency of carbon dioxide and the amount of flowing water can be controlled at the same time. That is, if the rotations of the motor of the air blower 150 are increased, the gas exchange becomes more efficient and the amount of water flowing through increases.

[0021] The apparatus 100 may be configured to determine, based on the information received from the first sensor 110 and the at least one second sensor 112 or 114, how to adjust an oxygen and carbon dioxide levels in the at least one tank 160. The apparatus may be further configured to control, based on said determination, aeration of the at least one tank 160 such that at least the carbon dioxide level in the at least one tank 160 is suitable for aquaculture. The apparatus 100 may be then configured to determine, after controlling said aeration, whether to perform oxygenation of the at least one tank 160, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank 160 are suitable for aquaculture. In general, aeration comprises both removal of carbon dioxide and addition of oxygen, and oxygenation comprises only addition of oxygen, without removal of carbon dioxide.

[0022] Using fish farming as an example of aquaculture, in case of intensive fish farming oxygen may be added to the water, either by aeration or pure oxygen dissolved in water. The water may be aired, i.e., ventilated, to remove carbon dioxide excreted by fish. It is desirable to convert ammonia (nitrification) into a non-toxic form or control the concentration (dilution) by changing the water.

[0023] So, aeration does both, increases oxygen and removes carbon dioxide while oxygenation affects in practice only the oxygen level of the water. With aeration the gas levels in the water can be get at most to a level of partial pressures (the share of the gas in question of all of the gases) comparable to levels in atmosphere. If using pure gas (oxygen),its partial pressure is high (100) and the water can be supersaturated with the gas in question, if needed.

[0024] In traditional fish farming, approximately 50,000 litres of water may be used for every kilogram of feed fed to the fish. The incoming water flowing into the at least one tank 160 brings with it all the oxygen needed by the fish and the water leaving the tank carries away the secretions of the fish, the most significant of which are carbon dioxide and ammonium. Often there is a need to reduce water use in order to control the water temperature and treat the effluent to reduce the environmental load. If water use is strangled, various water quality factors begin to decline and limit production.

[0025] The first limiting factor in production may be the oxygen content of the water. That is, the first issue may be the lack of oxygen when the amount of oxygen that comes with the new water decreases. If that issue is handled by dissolving oxygen in the water, the next issue may be too high carbon dioxide concentration, as the amount of effluent and the removal of carbon dioxide would also decrease. If that issue is also removed by airing carbon dioxide out of the water, the next issue may be related to ammonium excreted by fish.

[0026] The stage at which the ammonium in the water begins to limit production may depend on the form in which the ammonium is in the water. In the ionized form (NH4+), there may be up to tens of mg / 1 of ammonium in the water, but in the non-ionized form, as ammonia (NH3-N), the toxicity limit is significantly lower. For salmonids, the limit may be 0.0125-0.03 mg NH3-N / I. The form in which soluble ammonium / ammonia occurs in water may depend in particular on the pH value of the water. Temperature and salinity may also slightly affect the ammonium / ammonia ratio. After ammonia, the fourth limiting issue may be either the water solids content or the pH, depending on the ammonia removal method, the quality of the incoming water, and the other functions of the system.

[0027] The oxygen issue may be handled by aeration or oxygenation of water and the carbon dioxide issue by aeration of water. The toxicity of ammonium / ammonia may be controlled in water in production, e.g., by using a Recirculation Aquaculture System, RAS, in which ammonium is converted by biological water treatment (nitrification) through nitrite into nitrate and for example fish can tolerate quite high levels of nitrate. Alternatively, the toxicity of ammonium / ammonia may be controlled by using a Partial Re-use Aquaculture System, PRAS, or a hybrid flow-through, where the ammonium / ammonia content is kept within permissible limits by dilution, i.e., by using sufficient new water. In the latter option,the need for new water is primarily influenced by the pH of the water. The higher the pH, the higher the percentage of ammonia in NH3 form and the more water may need to be used. Other alternatives, such as ion exchange or electro-oxidation, may also be used.

[0028] There is a link between the carbon dioxide content of water, pH, and the presence of ammonium. Part of the carbon dioxide dissolved in water is formed by carbonic acid, which lowers the pH. The decrease in pH, on the other hand, shifts the NH3 / NH4+-balance in the NH4+direction, i.e., to a less toxic direction. The magnitude of the pH change per unit of dissolved carbon dioxide depends on the alkalinity of the water. How high the carbon dioxide content of the water can be allowed to rise again may depend on the tolerance time per species of fish. When these two factors are known, it is also known how much of the ammonium constraint can be removed by carbon dioxide-based pH control and how much by water exchange (dilution). Ammonium not only has adverse effects, but a suitably elevated ammonium level acts as a growth stimulant. It is noted that optimally elevated ammonium content may increase production by up to 40%.

[0029] There are several methods for aeration of water, such as the conduction of air into water or the conduction of water into air. The same methods may be also exploited for oxygenation. In addition, oxygenation may be done either at low pressure or at high pressure, allowing the pressure to enhance gas dissolution and allow for oxygen supersaturation (i.e., the water has an excess amount of oxygen while the pressure decreases).

[0030] With reference to FIG. 1 again, embodiments of the present disclosure enable automatic measurements and control of water quality (O2, CO2, NH3 / NH4+-relation) and keeping the water quality constant when oxygen is consumed and carbon dioxide produced in the at least one tank 160 of the system 100, even if there would be quick changes at level of the tank 160. The system 100 may be exploited to affect all four limiting factors (02, CO2, NH3, pH) and partly also to solids content of water in the tank 160.

[0031] All these four factors may be affected using a two-staged process, wherein aeration of the water in the tank 160 is first performed. Said aeration may include removal of carbon dioxide from water and addition of oxygen at most to 100% level. After said aeration it may be determined whether to perform oxygenation of the at least one tank 160, and in which extent. Said oxygenation may comprise adding only oxygen concentration, with a possibility to supersaturate water with oxygen above 100% level.

[0032] Alternatively, the factors in question may be affected using a three-staged process, wherein also the flow circumstances in the tank 160 may be affected. Furthermore, a current meter in the tank 160 and aeration may be implemented as a two-staged process, wherein fine-bubble aeration may be performed first and large-bubble aeration may be performed after said fine-bubble aeration. In some embodiments, said large-bubble aeration may be replaced with a water pump.

[0033] In some embodiments, in principle only one of aeration or oxygenation may be used. It is possible to keep the oxygen level of water in the tank 160 constant and always complying with the requirements of a specific aquatic organism. Also, the carbon dioxide concentration may be kept as constant and both, the carbon dioxide control and pH control, done within the tolerance limits of specific aquatic organisms, such as fish.

[0034] The system 100 comprises a water quality measurement system and an automatic control system for aeration and oxygenation. The system 100 further enables a two-staged gas exchange process, which comprises aeration of water at a first stage (if there is a need to remove carbon dioxide) and oxygenation at a second stage (if there is a need to add oxygen). The system 100 also enables constant measurements for oxygen, carbon dioxide and pH using the first sensor 110 and the second sensors 112 and 114. Only one of the carbon dioxide or pH measurements may be needed but if both measurements are performed, those would serve as backups for each other.

[0035] As an example, in case of fish farming a sufficient level of oxygen may be achieved by adjusting feeding of pure oxygen to a dissolving unit. A sufficiently low level of carbon dioxide may be achieved by controlling feeding of air to an aeration unit. Suitably elevated level of carbon dioxide decreases the pH level and the share of unionized ammonia. The adjustment of the pH level can be done by controlling how much of the carbon dioxide excreted by fish is aerated out of the water using aeration. The level of oxygen may be kept as constant, but if there is a need to decrease the pH level, the system 100 may feed more pure oxygen and less air. On the other hand, if there is a need to increase the pH level or to decrease carbon dioxide level, the system 100 may feed less oxygen and increase aeration, to ventilate carbon dioxide out of the tank 160.

[0036] The impact on solids content may be caused indirectly. First, the use of pure oxygen may decrease the solids content of water compared to increasing oxygen using aeration. In addition, the water quality measurement and control system may be used todevelop flow and improve tank hydraulics (e.g., improving spinning of water around the bottom well so that the tank works as a swirl separator), so that the solids content leaves the tank 160 efficiently and rapidly.

[0037] Levelling of the variations in the water quality in the at least one tank 160 may be based on constant measuring and automation of water parameters, by adjusting constantly aeration and oxygenation at the tank or plant level.

[0038] Embodiments of the present disclosure therefore provide at least the following benefits:1) Stability of water parameters and welfare of aquatic organisms (on-line measurements automation per tank to recognize and fix the issues); For example, feeding of fishes may increase oxygen consumption by 40%, followed by swings in the carbon dioxide level of the water in the tank 160, pH and ammonium / ammonia ratio, which disturbs the fishes. This may also affect the growth rate and feed efficiency;2) Saving of energy and oxygen; Removing the carbon dioxide out of the system is the most energy consuming stage of water treatment of intensive farming. Accurate and measurement-based control of the tank 160 consumes electricity and oxygen only according to actual need;3) Saving of water (and energy needed for controlling the temperature of water); In oxygenized and aerated systems the limits for water use may be set by toxic effects of the ammonia level of water. By adjusting the level of carbon dioxide, it is also possible to control pH and affect the ammonium / ammonia -ratio;4) Savings in chemical expenses;5) pH-adjustment can be done by adjusting the level of carbon dioxide excreted by fishes;6) Benefits of a distributed system in risk management.

[0039] Embodiments of the present disclosure enable these benefits by providing the apparatus 120, such as a PLC, which is configured to receive, from the first sensor 110, information about an oxygen level in the at least one tank 160, wherein the at least one tank 160 is for aquaculture. The apparatus 120 is further configured to receive, from at least one of the second sensors 112 or 114, information about carbon dioxide and / or pH level in the at least one tank 160.

[0040] The apparatus 120 is further configured to determine, based on the information received from the first sensor 110 and at least one of the second sensors 112 or 114, how to adjust an oxygen and carbon dioxide levels in the at least one tank 160. The apparatus is also configured to control, based on said determination, aeration of the at least one tank 160 such that at least the carbon dioxide level in the at least one tank 160 is suitable for aquaculture, such as fish farming. The apparatus 120 is further configured to determine, after controlling said aeration, whether to perform oxygenation of the at least one tank 160, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank 160 are suitable for aquaculture.

[0041] In some embodiments, the apparatus 120 may be further configured to determine whether, and in which extent, to perform said oxygenation of the at least one tank 160 based on information received from the first sensor 110 after said aeration. That is, the first sensor 110 may perform measurements again after said aeration to get new measurement results. The first sensor 110 may then transmit the new measurement results to the apparatus 120, so that the apparatus 120 can take the new measurement results into account when considering how to perform said oxygenation.

[0042] In some embodiments, the apparatus 120 may be further configured to determine how to perform said aeration of the at least one tank 160 based on information received from the at least one second sensor 112 and / or 114. That is, the at least one second sensor 112 and / or 114 may perform measurements again after said aeration to get new measurement results. The at least one second sensor 112 and / or 114 may then transmit the new measurement results to the apparatus 120, so that the apparatus 120 can take the new measurement results into account when considering how to perform said aeration.

[0043] In some embodiments, the apparatus 120 may be further configured to perform said aeration of the at least one tank 160 such that at least carbon dioxide levels in the at least one tank 160 are suitable for aquaculture. That is, the apparatus 120 may be further configured to perform said aeration such that the oxygen and carbon dioxide levels are kept at a desired, constant level. Furthermore, the apparatus 120 may be configured to perform said aeration such that the NFfe-level and pH are kept at the same level, even though ammonium is excreted by fish changes, e.g., due to feeding.

[0044] In some embodiments, the apparatus 120 may be further configured to tune a ratio between said aeration and oxygenation of the at least one tank 160 such that moreoxygen is added to the at least one tank 160 compared to carbon dioxide that is removed from the at least one tank 160. That is, the apparatus 120 may be configured to tune the ratio to lower pH, if needed.

[0045] In some embodiments, the apparatus 120 may be further configured to perform said aeration and oxygenation of the at least one tank 160 such that a ratio between ammonium and ammonia in the at least one tank 160 is suitable for aquatic organisms. Thus, the growth stimulant effect of ammonium can be exploited and the need for new water minimized.

[0046] In some embodiments, the apparatus 120 may be further configured to perform said oxygenation of the at least one tank 160 by transmitting a control signal to a flow controller 130, thereby enabling automatic control.

[0047] In some embodiments, the apparatus 120 may be further configured to perform said aeration and oxygenation of each of the at least one tank 160 individually or of multiple tanks 160 jointly. That is, said aeration and oxygenation may be performed for one tank only, to enable controlling of each individual tank, or for multiple tanks, if needed.

[0048] In some embodiments, the apparatus 120 may be further configured control said aeration of the at least one tank 160 by guiding air to water in the at least one tank 160 or water to air in the at least one tank 160.

[0049] In some embodiments, the apparatus 120 may be further configured to perform said oxygenation of the at least one tank 160 by guiding oxygen to water in the at least one tank 160 or water to oxygen in the at least one tank 160.

[0050] In some embodiments, the apparatus 120 may be further configured to, upon determining not to perform said oxygenation, refrain from performing said oxygenation of the at least one tank 160. That is, the apparatus 120 may be configured so that it is not always mandatory to perform said oxygenation, if it is not necessary, thereby enabling efficient operation of the system 100.

[0051] In some embodiments, the apparatus 120 may be further configured to control, based on determining how to adjust an oxygen and carbon dioxide levels in the at least one tank 160, an amount of carbon dioxide that is removed from the at least one tank 160 by causing said aeration of water in the at least one tank 160.

[0052] In some embodiments, the apparatus 120 may be further configured to control said aeration of water in the at least one tank 160 by controlling a frequency converter 140 and an air blower 150 associated with the frequency converter 140.

[0053] In some embodiments, the apparatus 120 may be further configured to control said aeriation and oxygenation using one aeration-oxygenation system.

[0054] In some embodiments, the apparatus 120 may be further configured to receive, from the at least one second sensor 112 and 114, information about water carbon dioxide level and pH level in the at least one tank. That is, if both of the carbon dioxide and pH measurements are performed, those would serve as backups for each other.

[0055] FIG. 2 illustrates a second example of a system for aquaculture in accordance with at least some embodiments of the present disclosure. In view of FIG. 1, the system 100 illustrated in FIG. 2 further comprises a third sensor 116 and two air nozzles, 170 and 175. The air nozzles 170 and 175 may be diffusers. The third sensor 116 may comprise, e.g., a current meter sensor and / or an ammonium sensor.

[0056] The system 100 illustrated in FIG. 2 is a system, which enables controlling of the gas exchange and effectiveness of the flow independently. Said two air nozzles may be arranged to produce air bubbles of two different sizes. For example, the first air nozzle 170 may be a fine bubble nozzle and the second air nozzle 175 may be a large-bubble air nozzle. The apparatus 120 may be configured to control the feeding of air to the first air nozzle 170, if there is a need to enhance removal of the carbon dioxide. The apparatus 120 may be configured to control the feeding of air to the second air nozzle 175, if there is a need to increase the flow of water.

[0057] FIG. 3 illustrates a third example of a system for aquaculture in accordance with at least some embodiments of the present disclosure. In view of FIG. 1, the system 100 illustrated in FIG. 3 further comprises a third sensor 116, another frequency converter 145 and another air blower 155. The third sensor 116 may comprise, e.g., a current meter sensor and / or an ammonium sensor.

[0058] The system 100 illustrated in FIG. 3 is a two-staged gas exchange and flow system, which enables controlling of the gas exchange and effectiveness of the flow independently. Two air nozzles may be arranged to produce air bubbles of two different sizes and said air nozzles may be placed in channels, which work as air-lift pumps. The apparatus120 may be configured to control the feeding of air to the first air nozzle 170, if there is a need to enhance removal of the carbon dioxide. The apparatus 120 may be configured to control the feeding of air to a second air nozzle, if there is a need to increase the flow of water. Both feeds of air may also affect the flow of water.

[0059] FIG. 4 illustrates a fourth example of a system for aquaculture in accordance with at least some embodiments of the present disclosure. In view of FIG. 1, the system 100 illustrated in FIG. 4 further comprises a third sensor 116, another frequency converter 145 and another air blower 155. The third sensor 116 may comprise, e.g., a current meter sensor and / or an ammonium sensor.

[0060] The system 100 illustrated in FIG. 4 is a two-staged gas exchange and flow system, which enables controlling of the gas exchange and effectiveness of the flow independently. Two air nozzles may be arranged to produce air bubbles of two different sizes and said air nozzles may be placed in channels. Only the large bubble aeration may be performed via the riser pipe / channel, i.e., the up-riser pipe / channel and work as an air-lift pump. The apparatus 120 may be configured to control the feeding of air to a first air nozzle, if there is a need to enhance removal of the carbon dioxide. The apparatus 120 may be configured to control the feeding of air to a second air nozzle, if there is a need to increase the flow of water. Both feeds of air may affect the flow of water or only the latter air feeding may be used to affect the flow of water.

[0061] FIG. 5 illustrates a fifth example of a system for aquaculture in accordance with at least some embodiments of the present disclosure. In view of FIG. 1, the system 100 illustrated in FIG. 5 further comprises a third sensor 116, another frequency converter 145 and a propeller pump 180. The third sensor 116 may comprise, e.g., a current meter sensor and / or an ammonium sensor.

[0062] The system 100 illustrated in FIG. 5 is a two-staged gas exchange and flow system, which enables controlling of the gas exchange and effectiveness of the flow independently. Aeriation may be performed using a fine-bubble nozzle and flowing with the propeller pump. Therefore, it is possible to perform dissolving of oxygen completely without aeration.

[0063] In some embodiments, the system 100 may comprise a farming tank of any shape, e.g., circular, rectangular, hexagonal, octagonal or oval.

[0064] In some embodiments, the system 100 may comprise a farming tank elongated in an elongation dimension along a longitudinal axis and having a first tank end and an opposite second tank end in the elongation dimension. The system 100 may further comprise a first water treatment unit and a second water treatment unit connected to the farming tank and extending in the elongation dimension, which water treatment units comprise first ends facing the first tank end and opposite second ends facing the second tank end, which ends comprise one or more than one treated water end outlet configured to insert treated water flow into the farming tank and / or one or more than one water end inlet configured to remove water from the farming tank, wherein the first water treatment unit and the second water treatment unit are arranged on the opposite sides of the longitudinal axis X of the farming tank.

[0065] Such an aquaculture system provides significant benefits. Because the water treatment units are connected to the farming tank and their operation is regulated directly from the farming tank or from water that is entering into the water treatment units, the water quality in the farming tank can always be kept constant, despite fluctuations in feeding, oxygen consumption and carbon dioxide production. A significant additional benefit of a tank-specific water treatment is biosecurity. The risks of pathogens spreading from one basin to another are significantly reduced when water treatment is decentralized and water does not mix in a water treatment unit common to all tanks. An additional advantage is the possibility to control the flow of water and generally achieve rotating motion with less energy than in a traditional rectangular mixed-cell raceways.

[0066] FIG. 6 illustrates an example device capable of supporting at least some embodiments of the present disclosure. Illustrated is device 600, which may comprise, for example, apparatus 120 of FIG. 1. Comprised in device 600 is processor 610, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 610 may comprise more than one processor. For example, processor 610 may comprise at least one application-specific integrated circuit, ASIC. Processor 610 may comprise at least one field-programmable gate array, FPGA. Processor 610 may be means for performing method steps in device 600. Processor 610 may be configured, at least in part by computer instructions, to perform actions.

[0067] Device 600 may comprise memory 620. Memory 620 may comprise randomaccess memory and / or permanent memory. Memory 620 may comprise at least one RAM chip. Memory 620 may comprise magnetic, optical, semiconductor and / or holographic memory, for example. Memory 620 may be at least in part accessible to processor 610. Memory 620 may be means for storing information. Memory 620 may comprise computer instructions that processor 610 is configured to execute. Memory 620 may also be implemented in Application-Specific Integrated Circuit, ASIC, or Field-Programmable Gate Array, FPGA. When computer instructions configured to cause processor 610 to perform certain actions are stored in memory 620, and device 600 overall is configured to run under the direction of processor 610 using computer instructions from memory 620, processor 610 and / or its at least one processing core may be considered to be configured to perform said certain actions.

[0068] Device 600 may comprise a transmitter 630. Device 600 may comprise a receiver 640. Transmitter 630 and receiver 640 may be configured to transmit and receive, respectively, information in accordance with at least one standard. Transmitter 630 may comprise more than one transmitter. Receiver 640 may comprise more than one receiver. Transmitter 630 and / or receiver 640 may be configured to operate in accordance with Ethernet, parallel bus and / or serial bus standards, for example.

[0069] Device 600 may comprise a near-field communication, NFC, transceiver 650. NFC transceiver 650 may support at least one NFC technology, such as NFC, Bluetooth, Wibree or similar technologies.

[0070] Device 600 may comprise user interface, UI, 660. UI 660 may comprise at least one of a display, a keyboard, a touch display, a physical controller, an external physical controller, an interface for an external physical controller, a vibrator arranged to signal to a user by causing device 600 to vibrate, a speaker and a microphone. A user may be able to operate device 600 via UI 660, for example to configure transition parameters.

[0071] Device 600 may comprise or be arranged to accept a user identity module 670. User identity module 670 may comprise, for example, a subscriber identity module, SIM, card installable in device 600. A user identity module 670 may comprise information identifying a subscription of a user of device 600. A user identity module 670 may comprise cryptographic information usable to verify the identity of a user of device 600 and / or tofacilitate encryption of communicated information and billing of the user of device 600 for communication effected via device 600.

[0072] Processor 610 may be furnished with a transmitter arranged to output information from processor 610, via electrical leads internal to device 600, to other devices comprised in device 600. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 620 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor 610 may comprise a receiver arranged to receive information in processor 610, via electrical leads internal to device 600, from other devices comprised in device 600. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 640 for processing in processor 610. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

[0073] Device 600 may comprise further devices not illustrated in FIG. 6. Processor 610, memory 620, transmitter 630, receiver 640 and / or UI 660 may be interconnected by electrical leads internal to device 600 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 600, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present disclosure.

[0074] FIG. 7 illustrates a flow graph of a method in accordance with at least some embodiments of the present disclosure. The steps of the illustrated method may be performed by apparatus 120, for example.

[0075] At step 710, the method may comprise receiving, from a first sensor, information about an oxygen level in at least one tank, wherein the at least one tank is for aquaculture. At step 720, the method may comprise receiving, from at least one second sensor, information about carbon dioxide and / or pH level in the at least one tank. At step 730, the method may comprise determining, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank. At step 740, the method may comprise controlling, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level inthe at least one tank is suitable for aquaculture. Finally, at step 750, the method may comprise determining, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank is suitable for aquaculture.

[0076] It is to be understood that the embodiments of the disclosure disclosed are not limited to the particular structures, method steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0077] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0078] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present disclosure may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present disclosure.

[0079] In an exemplary embodiment, an apparatus, such as, for example, apparatus 120, may comprise means for carrying out the embodiments described above and any combination thereof.

[0080] In an exemplary embodiment, a computer program may be configured to cause a method in accordance with the embodiments described above and any combination thereof.In an exemplary embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a method comprising the embodiments described above and any combination thereof.

[0081] In an exemplary embodiment, an apparatus, such as, for example, apparatus 120, may comprise at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform the embodiments described above and any combination thereof.

[0082] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the disclosure can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

[0083] While the forgoing examples are illustrative of the principles of the present disclosure in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the disclosure. Accordingly, it is not intended that the disclosure be limited, except as by the claims set forth below.

[0084] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY

[0085] At least some embodiments of the present disclosure find industrial application in aquaculture, such as fish farming.ACRONYMS LISTASIC Application-Specific Integrated CircuitFPGA Field-Programmable Gate ArrayPLC Programmable Logic ControllerPRAS Partial Re-use Aquaculture SystemRAS Re-use Aquaculture SystemUI User InterfaceREFERENCE SIGNS LIST

Claims

CLAIMS:

1. An apparatus for aquaculture, comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to:- receive, from a first sensor, information about an oxygen level in at least one tank, wherein the at least one tank is for aquaculture;- receive, from at least one second sensor, information about carbon dioxide and / or pH level in the at least one tank;- determine, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank;- control, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture; and - determine, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.

2. The apparatus according to claim 1, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- determining whether, and in which extent, to perform said oxygenation of the at least one tank based on information received from the first sensor after said aeration.

3. The apparatus according to claim 1 or claim 2, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- determine how to perform said aeration of the at least one tank based on information received from the at least one second sensor.

4. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- perform said aeration of the at least one tank such that at least carbon dioxide levels in the at least one tank are suitable for aquaculture.

5. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- tune a ratio between said aeration and oxygenation of the at least one tank such that more oxygen is added to the at least one tank compared to carbon dioxide that is removed from the at least one tank.

6. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- perform said aeration and oxygenation of the at least one tank such that a ratio between ammonium and ammonia in the at least one tank is suitable for aquatic organisms.

7. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- perform said oxygenation of the at least one tank by transmitting a control signal to a flow controller.

8. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- perform said aeration and oxygenation of each of the at least one tank individually or of multiple tanks jointly.

9. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- control said aeration of the at least one tank by guiding air to water in the at least one tank or water to air in the at least one tank; and / or- control said oxygenation of the at least one tank by guiding oxygen to water in the at least one tank or water to oxygen in the at least one tank.

10. The apparatus according to any of claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- upon determining not to perform said oxygenation, refrain from performing said oxygenation of the at least one tank.

11. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- control, based on determining how to adjust oxygen and carbon dioxide levels in the at least one tank, an amount of carbon dioxide that is removed from the at least one tank by causing said aeration of water in the at least one tank.

12. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- cause said aeration of water in the at least one tank by controlling a frequency converter and an air blower associated with the frequency converter.

13. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- control said aeriation and oxygenation using one aeriati on-oxygenation system.

14. The apparatus according to any of the preceding claims, wherein the at least one memory further stores instructions that cause, when executed by the at least one processing core, the apparatus at least to:- receive, from the at least one second sensor, information about water carbon dioxide level and pH level in the at least one tank.

15. A system, comprising a first sensor, at least one second sensor and an apparatus for aquaculture, wherein- the first sensor is configured to transmit information about an oxygen level in at least one tank to the apparatus, the at least one tank being for aquaculture;- the at least one second sensor is configured to transmit information about carbon dioxide and / or pH level in the at least one tank to the apparatus; and- the apparatus is configured to:o determine, based on the information received from the first sensor and the at least one second sensor, how to adjust an oxygen and carbon dioxide levels in the at least one tank;o control, based on said determination, aeration of the at least one tank such that at least the carbon dioxide level in the at least one tank is suitable for aquaculture; ando determine, after controlling said aeration, whether to perform oxygenation of the at least one tank, and in which extent, such that the oxygen and carbon dioxide levels in the at least one tank are suitable for aquaculture.

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