Seawater Desalination Systems

Seawater Desalination Systems

Seawater desalination systems are used to supply fresh water from sea water. Seawater salinity is variable according to geographical location and TDS value varies from 10.000 to 45.000 mg/l. The Caspian sea water TDS value can be up to 10,000 mg/l while the Red Sea water TDS value can be up to 45,000 mg/l. TDS value of Mediterranean water is about 35.000 mg/l. Reverse osmosis technology is applied in desalination of sea water. The seawater, which is pressurized to the reverse osmosis membranes by means of the high pressure pump, purified water molecules are passed through the reverse osmosis membranes and the purification is provided. By the way, the concentrate wastewater phase is discharged. Reverse osmosis membranes which is used in seawater desalination systems not only can operate at higher pressure but also  higher ion removal than standard RO membranes. Raw sea water must be pretreated before the reverse osmosis unit. Preliminary treatment processes applied before sea water RO systems include chlorine dosage, ultrafiltration, multimedia sand filtration, activated carbon filtration, SMBS dosage, acid dosage, pH adjustment, antiscalant dosage, microfiltration etc. The high salinity and corrosion resistance of sea water RO systems design is an important issue. Seawater RO systems are equipped with corrosion resistance material by applying PVC material in low pressure lines and duplex stainless steel material in high pressure lines. Energy saving can be achieved by using energy recovery units (Pelton turbine, ERI, etc.) in seawater desalination systems on certain capacities.