Seawater Desalination

1
Seawater Desalination

• Although the ocean is a huge resource of
  minerals, plants, fish and animals, its most
  obvious use can be for drinking water. However,
  steps must be taken to separate the dissolved
  salts form the water.

2
Change in State

• By allowing water to freeze, evaporate or boil
  (distillation), the dissolved minerals are
  separated when the gaseous or solid water is
  removed leaving a brine (or very salty) solution
  which is further treated.

3
Ion Exchange Column

• This process passes seawater through a column
  which will exchange H for Na and OH- for Cl-.
  Thus removing salt and producing HOH (or H2O).

4
Electrodialysis

• Electricity is used to cause the salt ions to
  migrate out of the water through a semipermeable
  membrane toward other ions (H and OH-)

5
Osmosis

• Water tends to move from the side of a membrane
  with high water concentration to the side that
  has the low water concentration (fresh to salty
  water) to equalize concentrations
• Cellular osmosis

6
Reverse Osmosis

• Pressure is placed on the salty water to force
  the water through a semipermeable membrane
  leaving a brine slurry.

7
Analysis of Desalination Methods

• Which method would be easiest to use? (require
  least amount of equipment/effort?)
• Which method is most popular? Why?
• Which method would you most likely have in your
  house? Why?