Recirculation aquaculture is essentially a technology for farming fish or aquatic organisms by using the water in the production. This method is based on the use of mechanical and biological filters. The advantage of RAS is that it can be carried out at different intensities depending on how much water is recirculated or re-used.
In a recirculation system, it is necessary to treat water continuously to remove waste products excreted by the fish, and to add oxygen to keep the fish alive. It is therefore imperative to have an automated water quality monitoring system to ensure all parameters are in place. Beside saving huge resources and improving the quality of testing, automated system provides good repeatability and continuous testing (24 hours a day). It will also be able to send distress signal to user when certain parameters are out of range.
Facilities such as oxygenation with pure oxygen can be done by DO transmitter, with limits set to provide alarm to notify user that the particular tank required aeration. Ultraviolet light or ozone disinfection, automatic pH regulation and denitrification process (parameters such as NH3, NO2 and NO3) are critical parameters to look out for.
In the degassing tank, oxygen enters through the gills, and is needed to produce energy and to break down protein, whereby carbon dioxide (CO2) and ammonia (NH3) are produced as waste produced as waste products. Degasser in RAS is to remove carbon dioxide from the water. They play an important role when alkalinity is present in water. The nitrifying process produces acid (H+) and the pH level falls. For this reason, lime or sodium hydroxide (NaOH) or another base needs to be added to the water.
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