3. Drinking water production by seawater desalination for salt-free water
“Do not drink seawater while swimming” – parents advise their children when they are on vacation on the beach. While small amounts of swallowed seawater are not that dangerous when bathing, you should under no circumstances install seawater in your diet – even in an emergency. When drinking seawater, the drinker can easily die of thirst, even though he has actually taken liquid. The reason is the extremely high salt content of the seawater. As a result, it deprives the cells of cell water according to the principle of osmosis, instead of making it available to the body.
In some situations, however, it may be necessary to make seawater drinkable. Low-water states with sea access such as Israel rely on desalinating seawater for the population. In addition, it is easier to win drinking water on a voyage (for example, when sailing), instead of taking the required amount of water. This is possible with seawater desalination, which is possible in three different ways:
– reverse osmosis
– freezing procedure
Reverse osmosis has already been introduced. During evaporation, plants heat the seawater until it becomes gaseous. The sea salt remains in solid form because it has a different boiling point. Subsequently, the steam only has to be cooled until the water condenses in a separate vessel and liquefies again. The freezing process is a bit more expensive and more expensive. Facilities cool the seawater, forming salt-free ice crystals. The ice crystals must then be washed with fresh water. In this type of drinking water production, a high energy consumption is needed. However, special systems can also be operated cost-effectively and sustainably with solar technology.