Aquaculture is the fastest growing sector within food production and the land-based recirculation aquaculture systems (RAS) is booming worldwide right now.
The year of 2020 has been completely affected by the Covid-19 and I believe the present pandemic will be pushing us even further towards increasing self-sufficiency to focus more on local production.
The use of RAS makes it possible to farm any species anywhere because the physical and chemical conditions of the system’s water are being controlled. It is possible to farm Kingfish (Seriola lalandi) in a land-based facility in Denmark at a constant temperature of 21 degrees Celsius despite the cold climate and the fact that Kingfish doesn’t even exist at that latitude.
The increasing degree of recirculation in the latest generation of RAS makes it easier to find suitable sites because the need for new intake water is limited and the discharge can be cleaned to meet any environmental restrictions.
A modern salmon farm can be located inland and it is possible to clean whatever source of intake water available with powerful tools such as microfiltration, ozone and UV.
In a RAS the toxic ammonia from the excretion of the fish is continuously transformed and detoxified to nitrate by the bacterial nitrification process in the biofilter.
The volume of new intake water mainly dictated by the volume needed to dilute the internal nitrate concentration below a threshold value of often 80mg nitrate per litre. By adding a denitrification step where nitrate is transformed to free nitrogen (N2) by an anoxic bacterial process it is possible to reduce the need from 300-500 litres to 30-50 litres per kg of feed. This reduction of intake water and discharge water will only make it easier to find new suitable locations for the expansion of RAS.
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