by Daniel Jackson, Content Editor, International Aquafeed
Aquaculture is a rapidly growing industry; it will soon overtake wild fisheries as our dominant source of seafood. One of its main advantages is that it is more sustainable and environmentally friendly than traditional fish farming, which has high feed requirements, water use, and makes a significant impact on the local environment by re-leasing effluents. This is a problem that could be solved by the use of intensive recirculating aquaculture systems.
Traditional saltwater aquaculture setups, in which fish are kept in tightly packed offshore pens, produce huge amounts of pollution. It is estimated to be equivalent to the raw sewage produced by a town of several thousand people, and it all flows directly into the ocean.
Aquaculture is a rapidly growing industry; it will soon overtake wild fisheries as our dominant source of seafood. One of its main advantages is that it is more sustainable and environmentally friendly than traditional fish farming, which has high feed requirements, water use, and makes a significant impact on the local environment by re-leasing effluents. This is a problem that could be solved by the use of intensive recirculating aquaculture systems.
Traditional saltwater aquaculture setups, in which fish are kept in tightly packed offshore pens, produce huge amounts of pollution. It is estimated to be equivalent to the raw sewage produced by a town of several thousand people, and it all flows directly into the ocean.
In a standard setup water would first be filtered to remove any solid material, then passed through a biofilter to convert ammonia (which is excreted by fish) into nitrate. After leaving the vessel holding fish the water is first treated for solids before entering a bio-filter to convert ammonia, before degassing and oxygenation, often followed by heating/cooling and sterilisation.
Each of these processes can be completed by using a variety of different methods and equipment, but regardless all must take place to ensure a healthy environment that maximises fish growth and health.
History
The earliest scientific research on RAS was conducted in Japan in the 1950’s. These early trials focused on biofilter design for carp production and were driven by the need to use limited water resources more productively.
At the same time European and American scientists attempted to adapt technology first developed for sewage treatment. Despite a strong belief by pioneers in the commercial viability of their work, most studies focused on science and the viability of the model in terms of chemistry. Furthermore, most of early trials were conducted in laboratories at very small scales.
As a result of these early mismanaged trials, many companies sold systems that were bound to fail resulting in scepticism amongst investors and delays in further technical improvement. Some simple but costly early problems were relatively easy to redress whilst others have proved more difficult.
Read more, HERE.
The Aquaculturists
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