Seawater reverse osmosis with energy recovery

The Porto Santo seawater reverse osmosis plant has been designed to provide per day 500 m³ of potable water with a total dissolved solids content of 500 ppm from seawater with a total dissolved solids content of abt. 34000 ppm.The plant consists of four independent units with an output of 125 m³ per day each. Three units are fed by high pressure pumps equipped with electro-motors and one unit by a high pressure pump equipped with a hydro-turbine. The high pressure reject stream from each unit is directed into a manifold pipe which powers the hydro-turbine. In this way power consumption of the high pressure pump is reduced by 25 percent. Without energy recovery consumption would have been 7.5 kWh/m³ and with the installed turbine this is as low as 5.6 kWh/m³ of product.