The process of water desalination is a set of methods to remove most of the mineral salts of salty or brackish water in order to make them sweet or drinkable, therefore, intended for consumption. This procedure can be used for both the sea water and for the treatment of brackish water or reservoirs with large amounts of impurities.
See too: oceans and seas
We know that just under 3% of all planet water is sweet, that is, fit for consumption. However, of this total, most is concentrated in the glaciers of the Arctic and of theAntarctica, so that the growing consumption of this natural resource, as well as its poor distribution across the planet, demands the realization of alternative forms of production in order to avoid aggravating the thirst problem.
Currently, there are several countries that carry out desalination for the production of potable water. This is the case, for example, of the Saudi Arabia, whose process accounts for about 70% of all fresh water consumed in the country. Other countries that also adopt this strategy are Israel, the United Arab Emirates, several states in the United States, Kuwait, Japan, Australia, Algeria, among others. At the
Brazil, nine states also have regions that have this technique for the generation of drinking water.How is water desalination carried out?
there are several physicochemical processes for the removal of most mineral salts from salt water, among which four of them can be highlighted:
→ Evaporation or thermal desalination
It is the “classic” and simplest type of desalination. The water is stored in a tank covered by some transparent material, where it receives Sun light, heats up and starts to evaporate. The steam, which accumulates in the upper part of the tank, gradually condenses, turning back into water without the presence of previously existing salts. Thus, it is captured and transferred to another tank, where it is stored and directed to consumption. The best way to carry out this method is through natural solar heating, as other ways to generate heat they can cause environmental damage and high energy consumption.
Occurs when a strong pressure on water, in order to displace it towards some membranes that are capable of separating practically all the water from mineral salts and other impurities present in the original volume. most of the desalination plants current uses this method, which requires costs in cleaning and replacement of osmotic membranes.
Explanatory scheme of reverse osmosis
→ Multistage Distillation
In this method, the water is heated in a pipe, where it enters boiling and goes through successive processes of distillation, being sequentially heated and transferred to points with different pressure levels. This process guarantees greater water purity, but it is more expensive.
→ Freezing
water has melting and boiling points different from other substances. So, just like the evaporation ensures that only water evaporates, separating from salts and impurities, freezing follows the same principle. However, this technique still needs more testing and application.
The advantage of water desalination is the possibility to guarantee the distribution of drinking water to poor regions this resource, which can become a good solution to the problem of thirst in various parts of the world. The main disadvantage of desalination is its high cost, which is currently five times greater than water treatment for reuse, even though the values have decreased substantially over the past few years.
Also, there are the environmental impacts generated both by heating systems, which can be polluting, and by the poor destination of the material that is produced from its removal from salt water. Despite this, the trend is to have an increase in this procedure worldwide, mainly due to the fact that the Water consumption come increasing at levels much higher than the population growth.
Know more:Demographic growth and scarcity of natural resources
By Me. Rodolfo Alves Pena
Source: Brazil School - https://brasilescola.uol.com.br/geografia/dessalinizacaoagua.htm