Method of fish farming in a recirculating aquaculture system

Abstract

The invention relates to a method of fish farming in a recirculating aquaculture system (RAS) comprising a fish holding unit (2) in fluid communication with a water supply device (3), the fish holding unit containing a volume of water defining a water depth, the water having a certain osmolality, oxygen concentration, temperature and pH, the method comprising the steps of: providing the water supply device with a flow of non-recirculating water, the non-recirculating water differing from the water in the fish holding unit in at least one of osmolality, oxygen concentration, CO2 concentration, N2 concentration, NH4+ concentration, temperature and pH; providing feed pellets (31); and adding the feed pellets to the non-recirculating water and hydraulically transporting the feed pellets to the fish holding unit. The method allows for a more efficient operation of the RAS facility. The invention also relates to a RAS facility.

Description

Background Technology

[0001] This invention relates to a method and system for raising fish, and more specifically to a method for delivering feed to a recirculating aquaculture system (RAS) and a RAS.

[0002] Farmed fish and shellfish rely on feed delivered to their aquaculture sites (such as cages or enclosures in the sea, flowing water connected to rivers or ponds, or onshore sites like RAS facilities) to receive all the necessary nutrients. In most of the equipment used today to transport fish feed to feeding sites, pneumatic or mechanical principles are prevalent. Typically, in the case of pneumatic conveying, feed pellets are blown by a fan or air compressor. It is well known that pneumatically conveying feed pellets can lead to pellet degradation and produce up to 7% ash and fine powder, as described in WO 2015067955. Furthermore, the pipes used for conveying feed suffer wear due to friction between the pipe walls and the pellets.

[0003] Steel pipes are heavy, require additional support, and are expensive, while plastic pipes are cheaper but require more maintenance and release microplastics into feed and aquaculture facilities. Feed pellets produce fine dust and ash, resulting in considerable costs and must be minimized. This corresponds to the loss of feed and essential / limiting nutrients and pollutes the surrounding environment. In the case of RAS facilities, this also puts stress on the mechanical and / or (micro)biological filters used to clean the water in the aquaculture system. Another well-known problem is that some fish (especially salmon) are very picky eaters, frequently spitting out feed or refusing to eat if they find the feed unpalatable. Feed that fish spit out or do not eat immediately may dissolve over time, further burdening the mechanical and / or (micro)biological filters of the RAS facility.

[0004] Alternative methods for delivering fish feed include hydraulic conveying, as described in WO 2002056676, which relates to a system that uses hydraulic feeding to deliver feed below the water surface, particularly relevant to benthic fish species such as catfish, turbot, and halibut. Hydraulic conveying is also known in WO 2011064538 and WO 2015067955, which describe how hydraulic conveying of aquaculture feed is used to wet dry fish feed pellets to improve their digestibility. Wetting the feed involves a significant amount of conveying, resulting not only in water entering the feed but also in the leakage of nutrients and oils from the feed into the water.

[0005] NO149372 discloses a device for conveying feed to an aquaculture enclosure (sea cage) floating in the sea. The size of the sea cage is limited by the effective delivery of feed to the sea cage. In this device, the feed comes into contact with a high-speed water jet and is propelled into the sea cage by air, allowing the feed to diffuse within the largest possible portion of the sea cage.

[0006] WO 2016160141 discloses a modular shrimp production system. This system includes a production sub-unit module, a RAS module, a feed distribution module, and a computer control module. The system is modularized and integrated into a multi-stage, synchronous, hyperintensive shrimp production system controlled by a custom-designed cyber-physical platform. This system is considered to provide a significantly lower total water volume per unit weight of shrimp produced compared to conventional technologies in shrimp aquaculture.

[0007] Nutrient loss is undesirable because additional feed is needed to provide the fish with the necessary nutrients, thus incurring additional costs.

[0008] Oil leakage from feed is not ideal, but it is tolerable when fish are raised in open water. However, in facilities such as RAS (Rapid Aquaculture System), the oil will settle in the system's filters, reducing their efficiency. This can lead to an increase in CO2 levels in the cleaned water, resulting in slower fish growth. Alternatively, fish density must be reduced, which is also detrimental.

[0009] Therefore, there is a need to develop a gentler and more efficient method of feed delivery, especially in RAS facilities, which may also provide feed in a way that is palatable to the fish. Summary of the Invention

[0010] The object of the present invention is to provide an improved, gentler method of feed delivery, which also provides feed in a manner palatable to fish. Therefore, according to a first aspect of the invention, this and other objects are achieved by a method of raising fish in a recirculating aquaculture system (RAS), the RAS comprising a fish-loading unit in fluid communication with a water supply device, the fish-loading unit containing a volume of water defining a certain depth, the water having specific osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration. + The method, which involves controlling concentration, temperature, and pH, includes the following steps: providing a non-recirculating water flow to the water supply device, the non-recirculating water having controlled concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4+ concentration. + The concentration, temperature, and pH are different from the water in the fish-loading unit; feed pellets are provided; and these feed pellets are added to the non-recirculating water and hydraulically conveyed to the fish-loading unit.

[0011] In the context of this invention, any aquaculture system using recirculated water can be referred to as a "recirculating aquaculture system" (RAS), and the method can be used with any RAS system. Such an aquaculture system can hold any suitable volume of water, but typically holds a maximum of 10... 12 m 3 Water. A typical fish-holding unit can contain 200m³ of water. 3 Up to 50,000m 3 The water between them. Typically, industrial aquaculture systems consist of several fish-filling units. These units can be up to 5,000 m². 3 Smaller fish-carrying units, up to 15,000m 3 Medium-sized fish tanks, or for example, 50,000 m³ 3 For example, 25,000 to 35,000m 3 Larger fish-filling units, or combinations thereof. RAS facilities typically have conduits for supplying clean water to the aquarium, and this method can be easily applied to existing RAS facilities, for example, by connecting conduits to the fish-filling units of the RAS facility, which allows feed pellets to be hydraulically delivered to the fish-filling units.

[0012] RAS typically includes a recirculation catheter. The recirculation catheter is described further below.

[0013] The water supply device is in fluid communication with the fish loading unit and defines the inlet point. Since the feed pellets in the water supply device are supplied using non-recirculating water, the inlet point can also be referred to as the feeding location. The water supply device may include or be a conduit, and the outlet of the conduit defines the inlet point. The water supply device can be in direct fluid communication with the fish loading unit, allowing the feed pellets to be hydraulically conveyed and added directly to the water in the fish loading unit.

[0014] In this method, feed pellets are hydraulically conveyed to the fish-loading unit. Therefore, the feed pellets are hydraulically conveyed to the fish-loading unit via non-recirculating water. In the context of this invention, the term "feed pellet" refers to any solid form of feed suitable for fish in the fish-loading unit. For example, feed pellets can be granules or microparticles with a size ranging from 0.1 mm to 50 mm or larger, and granules can be individual microparticles or clumps. Feed pellets can be dry, wet, or semi-wet feed, or even fragments of marine animals such as fish, shellfish, or marine plants. In specific embodiments, non-recirculating water feed pellets are any type of feed pellets described in PCT / DK2020 / 050057, which is incorporated herein by reference. For example, feed pellets can contain protein, feed stabilizers, water, and fatty acid components, with the fatty acids and water contained in the same phase, wherein the feed pellet contains 25% w / w or more of fatty acid components on dry matter, and wherein the water content is at least 30% w / w of the feed pellet.

[0015] In this method, non-recirculated water is supplied to the water supply device of the fish-filling unit. In the context of this invention, the term "non-recirculated water" refers to water that is not recirculated in the RAS (Recirculating Aqueous Supplies). Non-recirculated water can also be referred to as freshly supplied water or clean water, and these terms are used interchangeably. The water and non-recirculated water in the fish-filling unit will have at least certain osmotic concentration, conductivity, oxygen concentration, temperature, and pH, and these will be suitable for the fish raised in the fish-filling unit. In the context of this invention, "oxygen concentration" refers to dissolved O2. The water and non-recirculated water in the fish-filling unit can also be described by CO2 concentration, N2 concentration, NH4 concentration, etc. + The terms are described using concentration, and embodiments of the invention can monitor and adjust these. These terms include osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4. + Concentration, temperature, and pH can all be collectively referred to as "parameters." When "parameter" is mentioned in the context of this invention, it can refer to osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, NH4, etc. + Any of the concentration, temperature, and pH, and when referred to as "parameter" in the context of this invention, it can be osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, NH4. + Two or more of the following parameters: concentration, temperature, and pH. These parameters can be monitored or determined using any method known in the art. For example, any type of osmometer (e.g., a membrane osmometer) can be used to record osmotic concentration. Similarly, any type of conductivity meter can be used to record conductivity, any type of thermometer can be used to record temperature, and any type of spectrophotometer or chromatography, or any type of spectroscopy (e.g., near-infrared spectroscopy or mass spectrometry) can be used to record CO2, N2, and NH4.+ And pH can be recorded using any type of pH meter. This method can involve monitoring and adjusting CO2 and NH4. + When dissolved in water, they transform into other forms and convert between other forms, that is, depending on the pH, CO3 is... 2- HCO3 - And NH3, and in the context of this invention, all forms of the respective compounds may be monitored and / or adjusted as appropriate. Some related parameters may affect others. For example, osmotic concentration affects conductivity, while CO2 and NH4... + This can affect pH, and may also affect osmotic concentration and conductivity. Therefore, it is preferable that if a parameter is monitored and specifically adjusted, potentially affected parameters will also be monitored, and can be independently adjusted to obtain specific values ​​for the affected parameters. Water, especially water in fish-filled units, can also be described by biochemical oxygen demand (BOD), chemical oxygen demand (COD), and / or dry matter, which are also considered parameters in the context of this invention. BOD, COD, and / or dry matter represent the content of geosmin in the water, and these parameters should generally be as low as possible. Water in fish-filled units can be further described by H2S content and turbidity. As for BOD, COD, and / or dry matter, these should also be as low as possible. Therefore, the method of this invention may include monitoring and adjusting one or more of BOD, COD, dry matter content, H2S, and turbidity. H2S can be measured using any type of spectrophotometer or chromatography, or any type of spectroscopic method (e.g., near-infrared spectroscopy or mass spectrometry), and the content is generally expressed in μg / kg. Turbidity can be measured using any suitable technique (e.g., a turbidimeter), and turbidity is typically expressed in unit turbidimetric units (NTU).

[0016] The fish can be any desired fish, for example, either saltwater or freshwater fish. Although freshwater has a lower salinity, the advantages of this invention also apply to both freshwater and saltwater fish. Accordingly, osmotic concentration is typically provided by salts (especially NaCl) found in natural water (e.g., seawater). Osmotic concentration can also be referred to as "salinity," and the two terms are used interchangeably. Furthermore, the osmotic concentration of water, oxygen concentration, CO2 concentration, N2 concentration, and NH4+ concentration are also relevant. + The collective of concentration, temperature, and pH can be considered as providing a composition. In the context of this invention, "composition" when used to describe water will refer to osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4. +One or more of concentration, temperature, and pH. However, water may also contain other components, which can be considered using the term "composition." In particular, the composition of non-recirculating water includes osmotic concentration, oxygen concentration, CO2 concentration, N2 concentration, and NH4+ concentration. + The composition of the water in the fish-filling unit differs from that of the water in the fish-filling unit in at least one of the following aspects: concentration, temperature, and pH.

[0017] The water supply device can have any desired design. For example, the water supply device can include or be any type of conduit, such as a pipe, tube, or open channel. The water supply device is in fluid communication with the fish-loading unit, and therefore the water supply device can have a conduit whose outlet end is within the volume defined by the fish-loading unit. For example, the outlet end of the pipe can be above, at, or below the water surface in the fish-loading unit. The water supply device may also include a reservoir for clean water. In particular, before being supplied to the fish-loading unit as non-recirculating water, the clean water can be adjusted for at least one parameter to a different parameter than the corresponding parameter of the water in the fish-loading unit.

[0018] The RAS applicable to this method has a fish-holding unit. This fish-holding unit can have any desired shape and size. For example, the fish-holding unit can be open, such as an upward-opening tank, or it can be closed, such as a covered tank, etc.

[0019] Fish are highly sensitive to water properties, typically sensing and reacting to differences. In particular, fish learn to associate perceived differences with relevant observations. Therefore, by adding feed pellets to non-recirculating water and supplying this water with the feed pellets to the fish-filling unit, the fish recognize the feed pellets at the inlet point due to the difference between the non-recirculating water and the water in the fish-filling unit. The inventors have surprisingly discovered that by adding feed pellets to the water in the fish-filling unit using non-recirculating water, the fish in the fish-filling unit consume a larger proportion of the feed pellets compared to adding feed pellets without using any water (i.e., in a dry form), or compared to adding feed pellets using recirculating water. This provides more efficient operation of the RAS facility, with a larger proportion of feed pellets being converted into fish biomass.

[0020] RAS typically has a water recirculation conduit, which can include any type of cleaning or unit operation to adjust the water in the recirculation conduit. The recirculation conduit is in fluid communication with the fish-filling unit and recirculates water (recirculated water) from the fish-filling unit back to it. The recirculation conduit, in fluid communication with the fish-filling unit, defines the recirculation outlet point from which water is drawn from the fish-filling unit and the recirculation inlet point where the recirculated water returns to the fish-filling unit. The recirculation conduit is separate from the conduit of the water supply unit. The recirculation inlet point is separate from the inlet point (also known as the feeding location) defined by the water supply unit. Even though it can be, for example, at osmotic concentrations, oxygen concentrations, CO2 concentrations, N2 concentrations, NH4 concentrations... + By adjusting the water in the recirculation conduit in terms of concentration, temperature, and / or pH, the inventors have observed that, due to the much larger volumetric flow rate in the recirculation conduit, fish in the fish-filling unit do not recognize the inlet of the recirculation conduit in the fish-filling unit as a feeding site, even when the water composition is adjusted. In typical RAS facilities, water can be recycled, and in particular, water circulation can be continuous, with the amount of recycled water ranging from 95% to 99.9% or higher. Accordingly, non-recirculated water can be added to the fish-filling unit to maintain mass balance. Without being bound by theory, the inventors believe that excessively adjusting the water in the recirculation conduit to induce fish responses to differences would be detrimental to fish health, and the conversion rate of feed pellets in recirculated water would be less efficient than when feed pellets are supplied using non-recirculated water. Specifically, the volume of non-recirculated water in the water supply system is very small compared to the volume of water in the fish tank, typically less than 5% of the water in the aquarium, such as less than 1%, less than 0.5%, less than 0.2%, less than 0.1%, or less than 0.01%. This results in the non-recirculated water having lower salinity, oxygen concentration, CO2 concentration, N2 concentration, and NH4+ concentration. + The composition in terms of concentration, temperature, and pH can differ significantly from the water in the fish-filling unit without adversely affecting the fish. Therefore, the method of the present invention provides better control over RAS by using feed pellets added with non-recirculating water.

[0021] In this embodiment, due to water loss from the RAS, non-recirculated water is supplied to the fish-loading unit, either continuously or in batches, to maintain mass balance within the unit. In the case of batch supply of non-recirculated water, the supply may be paused, for example, for 1 to 24 hours without adding non-recirculated water to the RAS. Therefore, water recirculation in the RAS may reach 100% within several hours, after which non-recirculated water is supplied in batches. Batch supply of non-recirculated water allows a larger volume of non-recirculated water to accumulate in a container before being released into the RAS system. Therefore, batch supply of non-recirculated water allows for a larger flow of non-recirculated water to be used for hydraulically conveying feed to the fish-loading unit. Furthermore, in batch supply of non-recirculated water, the non-recirculated water can be adjusted in batches for one or more parameters.

[0022] Preferably, when feeding the fish, the non-recirculating water is adjusted only in one or more parameters compared to the water in the fish tank. For example, one or more parameters are adjusted shortly before adding feed pellets, and this adjustment is maintained as long as feed pellets are added. Similarly, when not feeding the fish, the parameters of the non-recirculating water should correspond to the parameters of the water in the fish tank. Thus, the advantage of feeding a larger proportion of feed pellets can be maintained more efficiently compared to supplying the fish tank with non-recirculating water adjusted in one or more parameters without feed pellets. In this embodiment, non-recirculating water adjusted in one or more parameters but not containing feed pellets is not supplied to the fish tank.

[0023] Typically, the recirculation and treatment of water in a fish tank largely depends on the fish density within the tank, as well as the quality of the feed pellets. Fish density is the number of fish per unit volume of water in the fish tank. Water is usually recirculated and treated to maintain good water quality for the fish. If the fish density is low, water recirculation can be less frequent, for example, 0.5 to 5 times per hour, while if the fish density is high, the water in the fish tank can be recirculated up to 20 times per hour. Similarly, water circulation can be reduced. Therefore, a 400m³ / tank is expected to be sufficient. 3 / hour to 100,000m 3 The recirculated water flow rate is between 0.01% and 1% per hour, and the non-recirculated volume is typically in the range of 0.01% to 1%.

[0024] The effects of this invention can be enhanced by actively controlling the composition of the non-recirculating water. For example, the method may include adjusting the osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration of the non-recirculating water compared to corresponding values ​​in the water in the fish-holding unit. + One or more of the steps involving concentration, temperature, and pH. The adjustment of this non-recirculating water preferably results in one or more of the following compared to the water in the fish-holding unit:

[0025] i) The osmotic concentration difference is at least 1 mOsm / kg;

[0026] ii) The conductivity difference is at least 0.01 μS / cm;

[0027] iii) The oxygen concentration difference is at least 0.05 mg / kg;

[0028] iv) The CO2 concentration difference is at least 0.05 mg / kg;

[0029] v) The N2 concentration difference is at least 0.05 mg / kg;

[0030] vi)NH4 +The concentration difference must be at least 0.05 mg / kg;

[0031] vii) The temperature difference is at least 0.1℃; and

[0032] Viii) The pH difference is at least 0.1.

[0033] Table 1 provides the specific ranges for these parameters.

[0034] Table 1

[0035]

[0036] Although the parameter differences in Table 1 are presented by adjusting the non-recirculated water to result in the listed parameter differences, it should be understood that in some embodiments, a non-recirculated water source that satisfies one or more of the parameter differences in Table 1 may be obtained. Therefore, in some embodiments, the method includes providing a non-recirculated water flow to a water supply device that differs from the water in the fish-loading unit in at least one aspect of the parameter differences listed in Table 1.

[0037] The water in the fish-filling unit can also be monitored for H2S and turbidity, and these parameters can be adjusted in non-recirculated water, for example, the difference between non-recirculated water and water in the fish-filling unit is defined in Table 2.

[0038] Table 2

[0039]

[0040] These parameters can be adjusted as needed. For example, the osmotic concentration can be adjusted by increasing or decreasing the concentration of NaCl, or optionally, the concentration of other salts found in natural water. Similarly, pH can be adjusted using compounds commonly found in nature. For example, pH can be increased using alkaline salts of carbonates or alkali salts (e.g., Na₂CO₃, K₂CO₃, CaCO₃, MgCO₃, or ammonia), and pH can be decreased using acids (such as HCl or NH₄Cl). Conductivity is usually adjusted simultaneously with the adjustment of osmotic concentration and pH. Preferably, conductivity is adjusted by adjusting osmotic concentration and pH simultaneously, rather than adjusting conductivity alone. The salinity, oxygen concentration, temperature, and pH of the non-recirculating water can be adjusted depending on the type of fish being raised in the fish tank. When monitoring one or more of the following parameters in the water of the fish tank: osmotic concentration, oxygen concentration, CO₂ concentration, N₂ concentration, NH₄⁺ concentration, temperature, and pH, and based on the salinity, oxygen concentration, CO₂ concentration, N₂ concentration, and NH₄⁺ concentration of the water in the fish tank... + Adjusting the corresponding parameters in non-recirculating water by monitoring one or more of the relevant values ​​of concentration, temperature, and pH can yield even better results.

[0041] Therefore, in a preferred embodiment, the method includes monitoring the osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration of the water in the fish-loading unit. + One or more of concentration, temperature, and pH, and adjusting one or more of the osmotic concentration, oxygen concentration, CO2 concentration, N2 concentration, NH4+ concentration, temperature, and pH of the non-recirculating water to provide at least one of the following compared to the water in the fish-filling unit:

[0042] i) The osmotic concentration difference is at least 1 mOsm / kg;

[0043] ii) The conductivity difference is at least 0.01 μS / cm;

[0044] iii) The oxygen concentration difference is at least 0.05 mg / kg;

[0045] iv) The CO2 concentration difference is at least 0.05 mg / kg;

[0046] v) The N2 concentration difference is at least 0.05 mg / kg;

[0047] vi)NH4 + The concentration difference must be at least 0.05 mg / kg;

[0048] vii) The temperature difference is at least 0.1℃; and

[0049] viii) The pH difference is at least 0.1.

[0050] In this embodiment, a larger proportion of the feed pellets will be consumed by the fish compared to when the characteristics of the water in the fish-feeding unit are not monitored.

[0051] When fish pellets are supplied to the aquarium via recirculated water, the recirculated water may contain substances such as geosmin or microorganisms. These substances reduce the palatability of the food, and their presence in the recirculated water is often unavoidable, as it is difficult to remove them even if the recirculated water is cleaned before adding the pellets. This drawback can be avoided by adding the pellets to non-recirculated water. Therefore, without being bound by any theoretical constraints, the inventors believe that fish will find the food provided in non-recirculated water more palatable than when it is provided in recirculated water.

[0052] In this embodiment, an appetite stimulant to increase fish appetite is added to the non-recirculating water flow, particularly upstream of the feeding point. The appetite stimulant can be krill meal or krill by-products, low-temperature fishmeal, fish oil, shrimp meal, or by-products. Certain parameters in the fish-filling unit (e.g., BOD, COD, dry matter content, H2S, and turbidity) should be kept as low as possible. When monitoring these parameters, the appetite stimulant can be included, particularly based on the values ​​of the corresponding parameters, in feed pellets to improve the appetite of the fed fish. Monitoring of BOD, COD, dry matter content, H2S, and / or turbidity in the water of the fish-filling unit is also envisioned, and non-recirculation can be adjusted in one or more of these parameters, if relevant. Monitoring of BOD, COD, and / or dry matter content is particularly relevant in the context of geosmin, and both can reflect undesirable amounts of geosmin. In a particular embodiment, the BOD, COD, and / or dry matter content, which are representative of geosmin content, are monitored in the fish-filling unit, and an appetite stimulant is added to the non-recirculating water based on the recorded values ​​of BOD, COD, and / or dry matter content. This appetite stimulant can mitigate the appetite-reducing effects of geosmin or other substances that may be present in the circulating water of a RAS facility. Without being bound by theory, it is believed that the aromatic properties of the appetite stimulant outweigh the sensory effects of geosmin; however, when the appetite stimulant is added to the recirculating water, a larger amount of the stimulant is required to overcome the odor of geosmin. Therefore, by adding the appetite stimulant to a geosmin-free non-recirculating water stream, a lower amount of stimulant is required, thus providing a cheaper fish-raising method. Any appetite stimulant can be used, and the stimulant can be, for example, volatile, unstable, or biodegradable.

[0053] In addition, this method improves the conveying of feed pellets because the feed pellets are conveyed more gently compared to pneumatic or mechanical conveying methods, thereby reducing the amount of ash and fine powder generated.

[0054] Another advantage of using non-recirculating water is improved biosecurity throughout the RAS facility, meaning the risk of infection and disease transmission within the aquaculture system is minimized. Poor water quality is a major source of disease transmission and a breeding ground for toxic gases such as H2S. Using non-recirculating water allows for strict control of BOD and COD.

[0055] All these advantages can be applied to methods used in aquaculture systems that operate with all or part of the water recirculated internally. Any fish can be raised using this method. For example, fish can be bottom-dwelling species such as catfish, turbot, and halibut, or mid- to upper-water species including salmon, trout, carp, tilapia, and basa. Non-recirculating water can also be suitable for aquaculture. For saltwater fish, the water is adjusted to resemble seawater, while for freshwater fish, the water is adjusted to resemble freshwater.

[0056] Differences in osmotic concentration may be due to differences in the concentration of one or more salts, especially salts commonly found in water bodies, such as NaCl or CaCO3.

[0057] The term "hydraulic delivery" is used to describe solid-liquid flow. In this context, the solid-liquid flow consists of feed (e.g., pellets or pellets) and water. Therefore, in the context of this invention, hydraulic feed delivery refers to the delivery of feed pellets to the fish loading unit via a liquid (particularly non-recirculating water) in a conduit (e.g., pipe, tube, or channel).

[0058] Hydraulically delivering feed pellets to the loading unit via a conduit allows for control over inflow conditions, such as the location of the inlet point (which is also the conduit outlet) within the loading unit and the dispersion of solid-liquid flow at that point. By hydraulically delivering feed via a conduit, the inlet point can be positioned relative to the water surface as needed. Furthermore, using a conduit allows for lower dispersion of feed pellets flowing into non-recirculating water at the inlet point, increasing the likelihood of creating localized areas with different water parameters within the loading unit due to non-recirculating water. Conversely, when using highly dispersive delivery methods such as spraying or jetting, non-recirculating water may be dispersed over a large area of ​​the loading unit, potentially diluting the effects of different water parameters.

[0059] It is preferable to obtain salt, CO2, N2, NH4 without reaching the desired concentration. + Differences in characteristics such as oxygen, temperature, or pH (which can stress fish or otherwise make the environment unsuitable for fishkeeping) can also cause problems. However, when such differences are only found in non-recirculating water, they are usually not large enough to negatively impact the fish in the tank.

[0060] In a preferred embodiment, the non-recirculating flow has a Reynolds number below 500,000. The Reynolds number can be below 400,000, for example, below 300,000, 200,000, 100,000, or 75,000. In a preferred embodiment, the non-recirculating flow has a Reynolds number in the range of 500 to 50,000. At such Reynolds numbers, the non-recirculating flow may be laminar.

[0061] Such a low Reynolds number ensures that the non-recirculating water mixes more slowly with the water in the fish-filling unit when it enters at the inlet. This slower mixing enhances the effect of differences in properties between the non-recirculating water and the fish-filling unit water, such as osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration. +Differences in one or more of concentration, temperature, and pH. Because the volume of non-recirculating water is small compared to the volume of water in the fish-filling unit, the Reynolds number of the non-recirculating water has a significant impact on the mixing rate between the non-recirculating water and the water in the fish-filling unit. Therefore, non-recirculating water flows with high Reynolds numbers should preferably be avoided, as they can cause the non-recirculating water to mix too quickly with the water in the fish-filling unit when it enters the inlet, thus reducing the effectiveness of providing feed pellets in the non-recirculating water. Those skilled in the art know how to adjust the water flow to obtain a suitable Reynolds number.

[0062] In some embodiments, the water flow velocity in the conduit is in the range of 0.5 to 2.5 m / s.

[0063] The inlet or feeding location can be located at the water surface, above the water surface, partially below the water surface, or below the water surface within the fish-filling unit. The inlet can be at any angle relative to the fish-filling unit; for example, feed pellets can be delivered upwards, downwards, or from one side relative to gravity, or at any angle in between. Additionally, the inlet can be at any depth within the fish-filling unit.

[0064] In a preferred embodiment, the feed pellets are hydraulically delivered to the fish-loading unit simultaneously below and above the water surface. This allows the fish to consume the feed pellets at lower pressure, as they do not have to compete for feed pellets that are only on the surface.

[0065] In a preferred embodiment, the feed pellet portion is hydraulically conveyed to the fish-loading unit below the water surface of the fish-loading unit, or preferably below the water surface of the fish-loading unit.

[0066] Having the inlet point above the water surface allows flowing non-recirculated water to fall into the fish-filling unit. When the inlet point is partially below or below the water surface, only a portion or no non-recirculated water falls into the fish-filling unit. Limiting or eliminating this inflow reduces the mixing rate of non-recirculated water with the fish-filling unit water. Therefore, having the inlet point partially below or below the water surface enhances the effectiveness of using non-recirculated water with different parameters.

[0067] In a preferred embodiment, the method further includes a step of cleaning the non-recirculating water before adding feed pellets to the water flow.

[0068] Cleaning should be understood to include any appropriate cleaning method to remove or break down microorganisms or viruses, or to remove or break down unpalatable substances, such as compounds or proteins produced by microorganisms. Such cleaning methods can be microfiltration, reverse osmosis, distillation, heat treatment, ultraviolet (UV) treatment, ozone treatment, or the use of chemicals to remove or bind substances present in water, for example, through ion exchange, chelation, oxidation, or precipitation.

[0069] On another front, the present invention relates to a recirculating aquaculture system (RAS) comprising: a fish-loading unit in fluid communication with a water supply device via a conduit, the fish-loading unit containing a certain volume of water at a defined depth, the water having a defined osmotic concentration, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration. + Concentration, temperature, and pH; the recirculating aquaculture system further includes a data processing unit configured to receive data from osmotic concentration measurement units, conductivity measurement units, oxygen concentration measurement units, CO2 concentration measurement units, N2 concentration measurement units, and NH4 concentration measurement units contained in the fish-loading unit. + The conduit receives data from one or more of the concentration measurement unit, temperature measurement unit, and pH measurement unit; wherein the conduit is configured to receive data from the data processing unit and provide at least one of the following compared to the water in the fish-filling unit:

[0070] i) The osmotic concentration difference is at least 1 mOsm / kg;

[0071] ii) The conductivity difference is at least 0.01 μS / cm;

[0072] iii) The oxygen concentration difference is at least 0.05 mg / kg;

[0073] iv) The CO2 concentration difference is at least 0.05 mg / kg;

[0074] v) The N2 concentration difference is at least 0.05 mg / kg;

[0075] vi)NH4 + The concentration difference must be at least 0.05 mg / kg;

[0076] vii) The temperature difference is at least 0.1℃; and

[0077] viii) The pH difference must be at least 0.1;

[0078] Furthermore, the conduit includes a feed loading section, such that when feed is added to the system in the feed loading section, the feed is hydraulically conveyed in the water via the conduit at the inlet point to the fish loading unit.

[0079] This system can achieve the same and further objectives as the method of the present invention.

[0080] The conduit can be configured to provide water that differs from the water in the fish-filling unit (i) to (viii).

[0081] A fish tank unit can have any shape suitable for containing liquid as needed. For example, it can be a cylindrical unit or a cuboid unit. It can be a tank, vessel, aquarium, pool, or similar object made of any material. It can also be a pond or pool in which some form of filtration and / or cleaning is used. The top of the fish tank unit can be open or can have a removable or fixed lid. Water is present in the aquaculture system when the system is used as needed (i.e., for raising fish). Most of the water is typically contained within the fish tank unit, which is where the fish are kept.

[0082] The conduit can be connected to a single fish-loading unit, or it can be connected to two or more fish-loading units. Feed can be added to a single non-recirculating flow at the feed loading section and then distributed to multiple individual fish-loading units. Feed can be supplied to one or more inlet points simultaneously, independently, sequentially, or continuously. The inlet point can be the outlet or outlet end of the conduit. The conduit can be in direct fluid communication with the fish-loading units such that the outlet is located within the volume defined by the fish-loading unit.

[0083] The conduit can have any suitable size and shape to accommodate a flow of water containing pellets. Typically, the conduit is cylindrical, but it can also be semi-cylindrical or elliptical. In some embodiments, the conduit is a cylinder with a diameter ranging from 20 mm to 100 mm (e.g., 22, 50, or 80 mm).

[0084] The conduit may include a regulating device that adjusts the flow of water into the conduit. This regulating device can be any suitable device, such as one or more of valves, pumps, and orifices. The water supply may originate from a pre-pressurized source, ensuring a suitable flow of water when water from the source is permitted to flow into the conduit. In this case, the device for regulating the flow of water may simply be a pressurized freshwater source.

[0085] In a preferred embodiment, the conduit includes means for regulating water flow, and the conduit and means for regulating water flow are configured to achieve a water flow with a Reynolds number below 500,000, preferably below 200,000, more preferably below 100,000, and even more preferably below 50,000 (e.g., in the range of 500 to 50,000).

[0086] In a preferred embodiment, the recirculating aquaculture system (RAS) has an inlet point that is partially below the water surface of the fish-filling unit or below the water surface of the fish-filling unit.

[0087] In a preferred embodiment, the catheter is configured for in-situ cleaning.

[0088] Clean-in-place is well known in the art. Using conduits with clean-in-place functionality allows for cleaning of the conduits without disassembly. The advantage of this cleaning is that it maintains the effectiveness of feeding with non-recirculated water without the serious inconvenience that would otherwise result from having to disassemble the conduits for cleaning.

[0089] In addition to the conduit, RAS typically also has a recirculation conduit. The recirculation conduit is configured to recirculate water from the fish-filling unit and return it to the fish-filling unit.

[0090] The water supply device can be used to supply non-recirculating water to the fish loading unit through a conduit, thereby the feed added in the feed loading section is hydraulically transported to the fish loading unit by non-recirculating water at the inlet point via the conduit. Attached Figure Description

[0091] In the following description, embodiments of the invention will be described with reference to schematic diagrams, in which:

[0092] Figure 1 A schematic diagram of a recirculating aquaculture system according to an embodiment of the present invention is shown. Detailed Implementation

[0093] refer to Figure 1 This illustration shows a schematic diagram of a recirculating aquaculture system (RAS) 1 according to an embodiment of the present invention. Generally, elements having the same or similar functions have the same reference numerals. RAS 1 includes a fish-filling unit 2 in the form of a tank with an upper opening. When the fish-filling unit 2 is used for its intended purpose (i.e., for fish farming), it includes a volume of water 99 forming a water surface 100 and a water depth D, as well as fish (not shown). A water supply device 3 is in fluid communication with the fish-filling unit 2. In the depicted embodiment, the water supply device 3 includes a reservoir 32 containing clean water, which supplies water to the water supply device 3 via a conduit 30. A feed storage unit 31, in the form of a silo, is located downstream of the reservoir 32 near a feed loading section 34. The feed storage unit 31 supplies feed pellets to the feed loading section 34. The feed loading section 34 includes a feed loading device (not shown), such as a Venturi injector, for introducing feed pellets into the water supply device 3 via the conduit 30. The amount of feed pellets can be adjusted before the opening is opened. Alternatively, the feed can be measured by volumetric or gravimetric methods before loading the feed pellets into the water. The arrows indicate the conduits in the recirculating aquaculture system 1 and the intended direction of water flow.

[0094] Feed pellets (not shown) are hydraulically conveyed to fish loading unit 2 at inlet point 21. Figure 1In the original description, RAS 1 is depicted as having multiple inlet points 21, but the RAS 1 of the present invention can have any number of the depicted inlet points 21. The inlet points 21 are configured to distribute non-recirculating water containing feed pellets from the water supply device 3 at different depths within the fish-holding unit 2 via conduits 30. One inlet point 21 is located above the water surface 100, another inlet point 21 is located at the water surface 100, and the two inlet points 21 are located at different depths within the water 99 of the fish-holding unit 2. This design is advantageous for different types of fish in the fish-holding unit 2, such as benthic fish or mid-to-upper-level fish that feed at different depths. The illustrated embodiment allows for the hydraulic delivery of feed to several depths / locations within the fish-holding unit 2 using non-recirculating water. In this particular embodiment, the inlet point 21 is located in the water 99 below the water surface 100.

[0095] Pump 33 is located upstream of inlet 21 and provides non-recirculating water flow from reservoir 32 in conduit 30. Feed is added to this non-recirculating water flow and is hydraulically conveyed to inlet 21 in water 99 of fish-holding unit 2. Pump 33 is shown in a specific location, but it can be located anywhere downstream of reservoir 32 in water supply device 3.

[0096] The RAS includes a recirculation system 4 comprising a cleaning system 41. The recirculation system 4 includes a cleaning system pump 42 capable of recirculating the water 99 liters 0.5 to 5 times per hour. Water from the fish-holding unit 2 is recirculated in the recirculation system 4 via a recirculation conduit 43. The cleaning system 41 may include any unit operation suitable for the RAS, such as one or more of a biological filtration unit, a solids removal unit, a pH control unit, a temperature control unit, an ultraviolet (UV) treatment unit, an oxygenation unit, a CO2 stripping unit, and an ozone treatment unit. Details not shown or described will be apparent to those skilled in the art.

[0097] RAS 1 includes a monitoring system 60 installed on or within the fish-filling unit 2 for monitoring parameters of the water 99 in the fish-filling unit 2. Monitoring system 60 includes a membrane osmometer, conductivity meter, thermometer, and pH meter. The specific components in monitoring system 60 may be specific to RAS 1, and may include more or fewer components than indicated. In embodiments, monitoring system 60 may also monitor the biochemical oxygen demand (BOD), chemical oxygen demand (COD), dry matter, H2S content, and / or turbidity of the water 99 in the fish-filling unit 2.

[0098] The water supply unit 3 includes an adjustment system 50 for adjusting the parameters of the non-recirculating water. The adjustment system 50 includes a data processing unit (not shown) that controls an additive supply unit 51. The adjustment system 50 and the additive supply unit 51 together control the parameters of the non-recirculating water. The additive supply unit 51 contains a reservoir of salts (specifically NaCl and Na₂CO₃) for controlling the osmotic concentration and a reservoir of HCl for lowering the pH. The pH can be increased using Na₂CO₃ while the osmotic concentration is modified using HCl. All of NaCl, HCl, and Na₂CO₃ also affect conductivity. The additive supply unit 51 may also include an oxygenation unit with an O₂ reservoir for adjusting the O₂ concentration of the non-recirculating water. The adjustment system 50 may also include a CO₂ stripping unit. The CO₂ stripping unit can also adjust the pH. Temperature is monitored by a thermometer, and the temperature of the non-recirculating water can be increased or decreased using a heat exchanger (not shown), increased using a heating element, or cooled using a Peltier element, etc. (not shown).

[0099] In a specific embodiment, the adjustment system 50 receives data related to the COD, BOD, and / or dry matter of the water 99 in the fish-filling unit 2, as representative of the geosmin content in the water 99. Optionally, the adjustment system 50 may also receive data related to H2S content and / or turbidity. The adjustment system 50 can then add an appetite stimulant from the additive supply device 51 to the fish-filling unit 2 based on the estimated concentration of geosmin in the water 99 or based on the H2S content and / or turbidity.

[0100] The water supply system 3 may also include a cleaning unit 35 for regulating, for example, non-recirculating water in the conduit 30. The cleaning unit 35 is configured to remove particulates, unwanted substances, or microorganisms or viruses, or combinations thereof. For example, the cleaning unit 35 may include a biological filtration unit, a solids removal unit, a UV treatment unit, and an ozone treatment unit.

[0101] RAS 1 includes a data processing unit 61 configured to acquire data from monitoring system 60 and control and adjust system 50 based on the acquired data. Figure 1 In the diagram, the data stream is represented by a dashed line. The data stream can be transmitted via a wired connection between the monitoring system 60, the data processing unit 61, the adjustment system 50, and the additive supply device 51, or it can be wireless.

[0102] Typically, the adjustment system 50 receives data from the data processing unit 61 to control the composition of the non-recirculating water based on the data of the water 99 in the fish-filling unit 2. When the fish in the fish-filling unit 2 are not fed, the non-recirculating water is adjusted to correspond to the water 99 in the fish-filling unit 2. Before and during feeding, the non-recirculating water is adjusted to achieve the following parameters: osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4+ concentration.+ At least one of the concentration, temperature and pH is different from the corresponding parameter in the water 99 in fish-filling unit 2.

[0103] The present invention is not limited to the embodiments shown and described above, but can be modified and combined in various ways.

[0104] Example

[0105] Example 1 – Hydraulic Feed Delivery in RAS

[0106] Feed (pellets) stored in the feed storage unit is added to the conduit on the RAS via a cam pump or injector. The amount of water relative to the pellets (shown below as a weight-based ratio of water to pellets) and the water flow are varied. Liquid loss, loss due to the generation of fine powder, and residence time are measured. The results are shown in Table 3 below.

[0107] Table 3

[0108]

[0109] In Table 3,

[0110] "Cam" indicates the use of a cam pump (which draws pellets from the feed storage unit, where the pellets are stored in water). "Ejector" indicates the use of an ejector to add pellets into the conduit (which draws the pellets downwards into the water flow within the conduit). The ejector is positioned after the pump in the conduit, thus avoiding the need for the feed pellets to pass through the pump itself.

[0111] "Liquid loss" refers to the weight loss caused by pellets in the water flow as oil leaves a conduit.

[0112] "Fine powder" refers to the weight loss of feed pellets caused by fragments, ash, and torn portions that are lost in the water flow through the conduit.

[0113] "Speed" refers to the flow rate of water containing pellets.

[0114] "Residence time" refers to the time that the pellet remains in the water flow in the conduit.

[0115] in conclusion:

[0116] Even with varying water-to-pellet ratios, hydraulic conveying of feed pellets typically provides very low fine powder generation and low liquid loss.

[0117] Example 2 – Feeding with recirculated water vs. feeding with non-recirculated water

[0118] Feeding methods using recirculated and non-recirculated water were compared in two RASs with corresponding fish-holding units of 19 meters in diameter and 7 meters in water depth.

[0119] In the first RAS, feed pellets are added to the recirculated water in the water recirculation conduit and hydraulically conveyed to the fish loading unit. Feed pellets are added after the recirculated water has undergone mechanical and biological filtration.

[0120] In the second RAS, feed pellets are added to non-recirculated water, i.e., fresh water, and are hydraulically conveyed to the fish loading unit.

[0121] The salinity and temperature of the freshwater were lower than those of the recirculated water. The recirculated water had a salinity of approximately 3% (by mass) and a dry matter content of 40,000 mg / L (primarily salt), and its salinity and temperature corresponded to those of the water in the fish tank. In contrast, the freshwater had a dry matter content of 190 mg / L. The operator further noted an earthy odor in the recirculated water.

[0122] The operator observed the following:

[0123] Fish fed with freshwater showed increased appetite compared to those fed with recirculated water. In RAS (Rapid Aquaculture System) using freshwater, fish gathered more at the feeding point. When the tubing was flushed with freshwater, the fish gathered at the feeding point before the feed pellets were added to the freshwater, indicating that the fish noticed the difference in water characteristics at the feeding point due to the freshwater inflow.

[0124] When fish congregate at the feeding point, the likelihood of the feed pellets being eaten increases, and the time the pellets remain in the fish tank decreases. This allows for better feed utilization—that is, a larger proportion of the feed is consumed—and also reduces the impact of uneaten feed on water quality, such as turbidity.

[0125] List of reference numerals

[0126] 1 Recirculating Aquaculture System

[0127] 2 Fish-loading units

[0128] 21 entry points

[0129] 3. Water supply device

[0130] 30 catheters

[0131] 31 Feed storage unit

[0132] 32 Water Storage

[0133] 33 pumps

[0134] 34 Feed loading section

[0135] 35 Cleaning equipment

[0136] 4. Recirculation System

[0137] 41 Cleaning System

[0138] 42 Cleaning system pump

[0139] 43 Recirculation catheter

[0140] 50 Adjust the system

[0141] 51 Additive supply device

[0142] 60 Monitoring System

[0143] 61 Data Processing Unit

[0144] 99 Water

[0145] 100 water surface

[0146] D. Water depth

Claims

1. A method for raising fish in a recirculating aquaculture system (1) abbreviated as RAS, the system comprising a fish-loading unit (2) in fluid communication with a water supply device (3), the fish-loading unit (2) containing a defined volume of water (99) at a defined depth (D), the water (99) in the fish-loading unit (2) having a defined osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration. + The recirculating aquaculture system (1) further includes a recirculation conduit (43) and the method includes the following steps: concentration, temperature and pH. Monitoring the osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration of water (99) selected from the fish-filling unit (2) + At least one of the parameters: concentration, temperature, and pH; Provide non-recirculating water flow to the water supply device (3); This non-recirculated water provides at least one of the following parameter differences: i) The osmotic concentration gradient is at least 1 mOsm / kg; ii) The conductivity difference is at least 0.01 μS / cm; iii) The oxygen concentration difference is at least 0.05 mg / kg; iv) The CO2 concentration difference is at least 0.05 mg / kg; v) The N2 concentration difference is at least 0.05 mg / kg; vi) NH4 + The concentration difference must be at least 0.05 mg / kg; vii) The temperature difference must be at least 0.1 °C; as well as viii) The pH difference must be at least 0.1; Provide feed pellets; as well as These feed pellets are added to the non-recirculating water and then hydraulically conveyed to the fish loading unit (2).

2. The method for raising fish in a recirculating aquaculture system (1) according to claim 1, wherein, The difference in osmotic concentration between the non-recirculated water and the water (99) in the fish-filling unit (2) is at least 1 mOsm / kg.

3. The method for raising fish in a recirculating aquaculture system (1) according to claim 1, further comprising adjusting the osmotic concentration, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration of the non-recirculating water. + One or more of the steps involving concentration, temperature, and pH.

4. The method for raising fish in a recirculating aquaculture system (1) according to claim 3, wherein, The adjustment of the non-recirculated water results in at least one of the following compared to the water (99) in the fish-filling unit (2): i) The osmotic concentration gradient is at least 1 mOsm / kg; ii) The conductivity difference is at least 0.01 μS / cm; iii) The oxygen concentration difference is at least 0.05 mg / kg; iv) The CO2 concentration difference is at least 0.05 mg / kg; v) The N2 concentration difference is at least 0.05 mg / kg; vi) NH4 + The concentration difference must be at least 0.05 mg / kg; vii) The temperature difference must be at least 0.1 °C; as well as viii) The pH difference is at least 0.

1.

5. The method for raising fish in a recirculating aquaculture system (1) according to claim 1, wherein, The Reynolds number of this non-recirculating water flow is in the range of 500 to 50,000.

6. The method for raising fish in a recirculating aquaculture system (1) according to claim 1, wherein, These feed pellets are partially hydraulically conveyed to the fish-loading unit (2) below the water surface (100) of the water (99) in the fish-loading unit (2) or below the water surface of the fish-loading unit.

7. The method of raising fish in a recirculating aquaculture system (1) according to claim 1 further includes a step of cleaning the non-recirculating water before adding the feed pellets, the cleaning including one or more of microfiltration, heat treatment, ultraviolet (UV) treatment and ozone treatment.

8. A recirculating aquaculture system (1), abbreviated as RAS, comprising: A fish-filling unit (2) is fluidly connected to a water supply device (3) via a conduit (30). The water supply device (3) includes an adjustment system (50). The fish-filling unit (2) contains a certain volume of water (99) at a defined depth (D). The water (99) in the fish-filling unit (2) has a certain concentration of osmotic pressure, oxygen concentration, CO2 concentration, N2 concentration, and NH4. + Concentration, temperature, and pH A monitoring system (60) installed on or within the fish loading unit (2), the monitoring system (60) including an osmotic concentration measuring unit, a conductivity measuring unit, an oxygen concentration measuring unit, a CO2 concentration measuring unit, an N2 concentration measuring unit, and an NH4 concentration measuring unit contained in the fish loading unit (2). + One or more of the concentration measurement unit, temperature measurement unit, and pH measurement unit; The recirculating aquaculture system (1) further includes a recirculation conduit (43), and The recirculating aquaculture system (1) further includes a data processing unit (61) configured to receive data from the monitoring system (60) regarding the osmotic concentration, conductivity, oxygen concentration, CO2 concentration, N2 concentration, and NH4 concentration in the fish loading unit (2). + Data for one or more of concentration, temperature, and pH. The adjustment system (50) is configured to receive data from the data processing unit (61) and provide water with at least one of the following differences in the conduit (30): i) The osmotic concentration gradient is at least 1 mOsm / kg; ii) The conductivity difference is at least 0.01 μS / cm; iii) The oxygen concentration difference is at least 0.05 mg / kg; iv) The CO2 concentration difference is at least 0.05 mg / kg; v) The N2 concentration difference is at least 0.05 mg / kg; vi) NH4 + The concentration difference must be at least 0.05 mg / kg; vii) The temperature difference is at least 0.1 °C; and viii) The pH difference must be at least 0.1; and The conduit (30) includes a feed loading section (34) such that when feed is added to the system in the feed loading section (34), the feed is hydraulically delivered in the water via the conduit (30) to the fish loading unit (2) at the inlet point (21).

9. The recirculating aquaculture system (1) according to claim 8, wherein, The conduit (30) is a cylinder with a diameter ranging from 20 mm to 100 mm.

10. The recirculating aquaculture system (1) according to any one of claims 8 to 9, wherein, The catheter (30) is configured for in-situ cleaning.

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