Click image to view full size image
Seawater, brackish water, and fresh water have different levels of salinity, which is often expressed by the total dissolved solids (TDS) concentration. Seawater has a TDS concentration of about 35,000 mg/L, and brackish water has a TDS concentration of 1000-10,000 mg/L. Water is considered fresh when its TDS concentration is below 500 mg/L, which is the secondary (voluntary) drinking water standard for the United States. Salinity is also expressed by the water's chloride concentration, which is about half of its TDS concentration.
The base method for seawater desalination is distillation. Approximately 620 kWh of evaporation enthalpy is necessary to obtain 1 t of drinking water.
In technical installations, a multiple stage flash (MSF) evaporator is used requiring approximately 100 kWH/t (hot steam at 2 bar) and 3.5 kWh/t of electric energy for pumpsIn contrast.
Seawater Desalination
