Sea water desalination is implemented when there is limited fresh water availability. This is particularly true in desert areas or when the available surface water is of extremely poor quality.
Desalination mostly applies to sea water, but can also be employed in presence of high-salinity brackish waters such as those coming from deep wells, lagoons or river estuaries with a remarkable sea water inflow.
The technologies employed by Cannon Artes in the desalination of sea water are based on membrane processes. In particular the “heart” of the process scheme is a Reverse Osmosis unit where saline water is pumped in cross flow on the elements with enough pressure to overcome the high osmotic pressure and enable a satisfactory recovery factor. Energy saving solutions are implemented with high-rejection energy saving permeators and with the use of an “energy recovery” device enabling the energy of the high pressure concentrate to be transferred to the incoming feed water, thus reducing the required power per unit of desalinated water.
Since seawater is a “living environment” with presence of micro-organisms and algae, key issues in the treatment of seawater are the filtration and debacterisation of the incoming water. The filtration could be performed again with membrane technologies (ultrafiltration and microfiltration) or with pressure-type media filters. Flotation can also be employed when there is a significant risk of “algae bloom” that could compromise in a short time any conventional filtration system.
Another important factor in the design of a seawater desalination plant is the correct material selection, because of the high corrosivity of sea water.