PRODUCTS
Atlantic Salmon (family Salmonidae) will be produced by the RAS:
Atlantic Salmon will initially be produced by the facility on the basis of the current South African market demands and consumer preferences.
The production strategy includes continuous harvesting for maximum system utilisation. Up to 2,000 ton (live weight) Atlantic Salmon will be produced per annum. This will be increased to 6,000 ton per annum via Stage 2 and 3 expansions.
The product will be supplied to the market as HOG (Head On, Gutted).
Atlantic salmon (Salmo Salar)
IN ADDITION TO THE PRIMARY PRODUCT, WHICH IS THE FINFISH, THE FOLLOWING
ADDITIONAL AQUACULTURE SPECIES WILL BE PRODUCED BY THE INTEGRATED MULTITROPHIC AQUACULTURE
SYSTEM AND WILL BE SUPPLIED TO THE MARKET
COCKTAIL OYSTERS
(60 g each) 180 to 270 ton per annum
SEA CLAMS
production rates to be confirmed
SEA CUCUMBERS
production rates to be confirmed
SEA ASPARAGUS
production rates to be confirmed
OVERVIEW OF FISH PRODUCTION
HOVER OVER THE NUMBERS BELOW AND CLICK FOR MORE INFORMATION:
FISH PRODUCTION
SYSTEM
SYSTEM
FISH PRODUCTION
SYSTEM
SYSTEM
The primary design objective of 4th generation RAS based technology is to replicate the best possible conditions of the ocean ecosystem without any of the negative environmental impacts and risks typically associated with conventional ocean-based fish farming operations. The other objective is to do this at the lowest possible energy per mass of fish produced.
Fish in a fish farm require feeding several times a day. The feed is eaten and digested by the fish and is used in the fish metabolism by supplying energy and nourishment for growth and other physiological processes. The typically feed conversion ratio in this RAS facility will be 1:1.2, i.e. 1.2kg feed will be required for each 1 kg fish produced.
Oxygen (O2) enters through the gills of the fish, with carbon dioxide (CO2) and ammonia (NH3) produced as waste products and again excreted via the gills into the water. Undigested feed is excreted into the water as faeces (suspended solids) and organic matter.
The fish tanks will be round concrete tanks in the Grow-out and Smolt units and circular tanks in the Pre-Smolt and Fry units. This fish tanks will be partly submerged into the ground, with the upper edge 1.2 meters above the finished floor level.
The fish farms systems can be described as follows:
HATCHERY AND FIRST FEEDING
Production is initiated in the Hatchery, where eggs are incubated. When they have reached the swim-up phase (after yolk sac consumption), they are transferred to the First Feeding fish tanks, where they are brought up to reach a mean weight of 2-5g. The incubation system provides a continuous and steady delivery of fry to the First Feeding system. The water supply is fresh water, maintained at a temperature of between 8 to 10 degrees.
The Hatchery and First Feeding Unit has a dedicated water treatment system.
FRY
Fish are transferred from the First Feeding system to the Fry system after a grading process. After transfer to the Fry system, the fish are brought up to 10 g over a period of approximately 50 days. The water source is again fresh water, maintained at a process temperature of between 10 to 14 degrees.
The Fry System comprises of 8 concrete tanks and is provided with a dedicated water treatment system.
PRE-SMOLT
The Pre-smolt System will receive fish from the Fry system and are brought up to approximately 50g over a period of 70 days. The fish are typically vaccinated in this section. The fish are graded during the transfer to the Pre-smolt system. This again will form a unified batch of fish.
The Pre-Smolt System is a concrete installation comprising of 6 fish tanks and is provided with a dedicated water treatment system.
SMOLT
Grading is also done when moving the fish from the Pre-smolt to the Smolt system. The process water will be around 13 to 15 degrees and will be a mix between the sea and freshwater intake, where the fish adapts from a fresh water environment to salt water. The fish remains in the Smolt system for approximately 190 days until it reaches an average size of 1000g, where it is graded and moved to the Grow-out systems.
The Smolt (juvenile fish) installation is built out of concrete and consists of 9 fish tanks, as well as a dedicated water treatment system.
GROW-OUT
The fish will enter the Grow-out as a unified batch where they will grow in size over a period of approximately 240 days from 1,000g up to a harvest size of about 5,200g, at which point they are moved to the Purge system. This system is made up of sea water and is maintained at temperatures of around 13 to 15 degrees.
Three Grow-outs are provided of 600MT each. The three Grow-outs will each have their own water treatment system and 8 large concrete fish tanks, reducing the risk of fish disease and parasites or human error.
PURGE
Recirculating the water means that some organic feed-derived substances accumulate in the water, which may unfavourably flavour the fish meat. For this reason, the fish is transferred from the Grow-out systems to a Purge system, where the fish are kept in clean water without feeding for 4-6 days to optimize flavour they are harvested and supplied to the market. This process is called ‘purging’ and is a common treatment in many RAS.
WATER TREATMENT &
SUPPORT SYSTEMS
SUPPORT SYSTEMS
The water treatment and auxiliary systems create the correct habitat for the fish.
In a recirculation system it is necessary to treat the water continuously to remove the waste products excreted by the fish and to add oxygen to keep the fish alive and well. Water is circulated from the outlet of the fish tanks to a mechanical filter and then a biological filter before it is aerated, stripped of carbon dioxide, oxygenated and returned to the fish tanks.
Waste water leaving the recirculation process accounts for approximately 1% of the total standing volume of water in the RAS and this comes primarily from the mechanical filter, where faeces and other organic matters are collected. The cleaning and flushing of sludge from the biofilters is added to the total discharged volume from the recirculation cycle.
Treating the waste leaving the RAS can be accomplished with secondary mechanical water treatment, which concentrates the sludge in the waste water. Mechanical dewatering takes place before the solid waste can be used as a high-quality fertilizer on agricultural land.
The cleaned waste water from where the organic matter (total suspended solids (TSS)) has been removed is called reject water. The reject water usually contains high concentrations of nitrogen (N), mainly in the form of nitrate, as well as Phosphorous (P). This reject water stream will be further treated in the integrated multitrophic systems, where the micro-algae, oysters and bottom feeders, as well as the macro algae, will consume up to 90% of the Nitrates and Phosphorus before the water is discharged back into the ocean (along with the cooling water return).
ENERGY SYSTEMS
CNC has an innovative approach to its energy systems, which aims to reduce the overall energy footprint of the facility and which will enable CNC to reliably power its facility by renewable energy.
Our approach to energy conservation includes utilising the thermal inertia available in the RAS system itself, i.e. in the water contained in the facility, to control the overall system energy input requirements via both the facility control systems and human intervention.
In Stage 1 of the facility development, up to 70% of all of the energy needs will be met by renewable energy, namely in the form of 2x 2,3 MW wind turbines. An additional 2x 2,3 MW wind turbines will be added per Stage (with solar PV also considered for later stages). Initially, any shortfall in renewable energy generation will be met via electricity supply from the national grid, however the intention will be for the facility to eventually run 100% off-grid and will include solar PV with batteries and possibly biogas to power solutions.
INTEGRATED MULTITROPHIC AQUACULTURE
An Integrated Multitrophic Aquaculture System (IMTAS) is defined as an ecosystem-based management approach that effectively mitigates the overabundance of nutrients introduced by fish farming. In the IMTAS, some of the food, nutrients and by-products considered “lost” from the finfish production facilities are utilised and converted into harvestable and healthy seafood of commercial value, while bio-mitigation (with the removal of nutrients) occurs. In this way, some of the externalities of fed monoculture are internalised, increasing the overall sustainability, profitability and resilience of the aquaculture stream.
The IMTAS system will include various aquaculture species, which will be selected in such a way that a balanced ecosystem is achieved and where different species feed off each other or complement each other.
