Northeast water scarcity and reverse osmosis

It is well known that water scarcity in the northeastern semi-arid is a problem that requires a priority response.

Its cause is low rainfall and irregular rainfall, and a geological structure that does not allow satisfactory accumulation of water in the subsoil, which even interferes in the river regime. Due to the soil, the water has, in most cases, high salinity - with chloride levels above 1,000 mg / L - which makes it unfit for human consumption *.

* The World Health Organization recommends 250 mg / L of chloride in the water for population supply.

Governmental actions have been established to prioritize access to water, including the use of desalination plants to improve groundwater quality. But some questions need to be observed.

The process of removing salts from water is done by reverse osmosis (a technique that forces water to pass through a semipermeable membrane in the opposite direction to natural osmosis), in which extremely salinized water becomes almost distilled water. This fact is very important because it can greatly influence the balance of salts in people's bodies.

Due to the high temperatures of the region, the population of the field is sweating a lot and, therefore, loses salts that must be replaced by the diet - which is known to be precarious in this region - and by the ingestion of liquids - this population is used to drinking water with salt content far above those recommended by WHO.

What to expect in the medium term with the consumption of this desalinated water? It can be expected that the population will enter a demineralization process, considering that the sources of replacement of this element no longer present the levels that had previously supplied the population.

The result is that a program of supplying the population with “first-world water” using desalination plants (a slogan widely publicized by governments) could in future be a vector of population demineralization. To correct this problem, it is necessary to think of mixing salt-free water with a small part of mineralized water, thus guaranteeing a water with saline contents suitable for the perfect functioning of the human body.

Still regarding the issue of desalination plants, another important aspect to be mentioned is the fate that should be given to the rejection of the material resulting from the water desalination process. This extremely salt-rich material is currently deposited in settling ponds or even placed outdoors without further concern, constituting a serious environmental problem to be solved by the researchers.

It is likely that the paths to be followed by the researchers concern the use of these salts for livestock purposes, as the semi-arid region is very lacking in the aspect of animal mineralization, fish farming, especially with Tilapia, which are extremely resistant to species. saline and cultivated environments irrigated with halophilic plants, such as the Atriplex, which need high salt water to develop.

Adapted from: SUASSUNA, J. Semi-arid Drinking Water: shortage announced.

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