AKVA group
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Recirculation Systems

Recirculation Systems

The Recirculation System

Recirculation Systems

Assured predictability, better fish welfare

With a history of having delivered high-end recirculated systems for more than 15 species around the globe; AKVA group has proved its position as a highly qualified and reliable partner for the aquaculture industry. Combining the unique split loop concept with components of superior quality enables our experienced engineers to tailor each system to perfectly meet the biological requiremens of any specie both in fresh- and in saltwater. The use of a special microparticle filter provides crystal clear water without fine particles that could otherwise damage the gills of sensitive fish.
Concrete - “a solid rock”
The most common way to build a recirculation system is the Concrete concept. With the AKVA group technology, this provides a minimum footprint and a reliable solution suitable for both fresh- and saltwater species.
Module based PE concept
Through a broad product range, the PE concept can be tailored to provide optimal water quality to any specie. Stand-alone PE components are also perfect for increasing performance in existing recirculated systems.
AkvaFlex, smart and compact
Cutting edge technology with a full-scale recirculated system compact enough to fit in a customized 40 foot container. The AkvaFlex is quickly installed and can also be moved if the future requirements should change.

A unique concept suitable for most species

A unique concept suitable for most species…
Species from A to Z...
Numerous other freshwater and saltwater species have already been cultured in recirculation systems.

Why choose AKVA group Recirculation Systems?

Why choose AKVA group Recirculation Systems?
The revolutionary split-loop design of the system maintains a perfect rearing environment resulting in better growth and maximum profitability. AKVA group is the only supplier specializing in recirculation systems for both freshwater and full salinity saltwater with many successful commercial scale projects.

“Time Magazine awards tuna tank farming”

The break-through in farming of Southern Bluefin Tuna in the tanks of Clean Seas Ltd. in Australia has been awarded the world’s 2nd best invention in 2009 by TIME Magazine. For the first time, Southern Bluefin Tuna successfully spawned in a controlled environment in captivity. Clean Seas are now hatching and rearing fingerlings in the tanks, after which the fish are transferred to ocean farming cages where they are grown to a harvest weight of 50-80kg. Consequently, consumption of this tuna can now be done based on environmentally sustainable principles while at the same time reducing the pressure on wild stocks.
2nd best invention in 2009!
The break-through of bluefin tuna farming was made possible using a AKVA group recirculation system.
Port Lincoln, Australia
The advanced tank farming technology was delivered to Clean Seas Ltd. in Port Lincoln, Australia from AKVA group Denmark.
An experienced partner
AKVA group has highly qualified project managers and more than 30 years of experience in designing and supplying viable recirculation systems.

The Recirculation Process

A standard Recirculation System from AKVA group will treat the effluent water from the fish tanks as follows:
  1. Mechanical Filter - removing solid particles larger than 50 microns.
  2. UV Filter - controlling bacterial dynamics and ecto-parasites.
  3. CO2 Stripper - removing CO2, nitrogen and sulphide residues.
  4. Bio Filter - removing organic matter and ammonia products.
  5. Micro Particle Filter - removing suspended particles in the 2-50 micron range.
The Recirculation Process…
Mechanical filtration
An efficient mechanical particle filter removes particles larger than 50 microns. This is crucial for optimal bio filter performance and general pathogen control.
Probiotic UV filter
The UV Filter provides efficient ultra violet water disinfection at low costs. The UNI design results in head loss of only 3 cm. The header pumps are the only in the system. The remaining flow is by gravity only.
Effective degassing
The CO2 Stripper provides efficient CO2 removal at low energy costs, including efficient stripping of nitrogen.
Fixed fluidized Bio filter
The fixed fluidised Bio Filter combines high performance with simple main-tenance and low operating costs. This multi-step concept has been developed for ultimate bio filter stability.
Automatic oxygen control
Stable oxygen levels are essential to all aquaculture systems, as periodical drops in oxygen levels reduce fish appetite, increase stress levels and mortality.
Unique split-loop design
To obtain optimal stability and efficiency, the flow through the bio filter can be reduced compared to the flow through of the CO2 Stripper. This reduces CO2 levels and increases growth and welfare.

Balance and design

The production unit design is imperative for a successful rearing facility, and the solution depends highly on the behavioral pattern of the species. The tank system should be designed to optimize the water flow characteristics so that exact water exchange rates for the different species and fish sizes can be achieved. For any type of tank, the inclination of the bottom has no importance with regards to the self-cleaning effect, but it makes complete draining possible when the tank is emptied.

It is important to note that construction of large tanks will always favour the circular tank as this is the strongest engineering design and the cheapest way of erecting large containments. There are many different issues to consider before deciding on the final tank design, and the answer is seldom straight forward.

AKVA group´s most suitable recirculation solution is carefully designed in close cooperation with the client, ensuring that the production reaches maximum capacity as quickly as possible.
recirculation solution
Circular/Octagonal tanks
High water velocity gives high self cleaning effect. Organic particles have a relatively short residence time depending on tank volume. This is due to the hydraulic pattern and gravitational forces, and the water column is moving around the centre.
D-ended raceways
The perfect combination between the circular tank and the common raceway. The D-Ended raceway is often referred to as a hybrid between the circular tank and the common raceway. It combines the self-cleaning effect of the circular tank with the efficient space utilization of the raceway.
Common raceways
In a raceway, no gravitational forces are created to make a current, and the hydraulics have no positive effect on the removal of the particles. If a fish tank is stocked efficiently with fish, the self-cleaning effect of the tank design will depend more on the fish activity than on the tank design.
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