Drinking water is a resource that is unfortunately increasingly scarce. The climate change is influencing decisively in the depletion of this resource. The years are getting warmer and the shortage of rainfall in the form of water and snow makes the droughts are longer. How to get more drinking water? Is a question that hundreds of scientists try to answer and this seems to be how to transform salt water into drinking water, in this article we will focus on the different methods developed so far to achieve this Transformation.
There is a resource that also offers nature that unlike what happens to drinking water, this with rising temperature is growing more and more, even becoming a real threat to different areas of the planet, we are talking about the Water from the oceans.
The problem is the composition of the seawater; the mineral salts make impossible its intake by the human being. 97.5% of the water contained in the planet cannot be consumed by humans because it is salty, which leaves a very low percentage of drinking water.
The solution is to get the way to purify seawater, that is, to use different technologies to desalinate salt water. The desalination plants seawater existed long ago but its use out expensive so only used in cases of extreme necessity.
The worsening situation and the shortage of drinking water has enabled researchers around the world to study the cheapest and most efficient way to convert this resource as abundant as sea water into drinking water.
Investment in research has begun to bear fruit, new technologies have been able to develop new systems and methods that are now viable and whose costs are reduced compared to the first desalination systems. Among this system, we find …
To know what is reverse osmosis, let us first know what osmosis is. Osmosis is based on a system of equilibrium. If two fluids come into contact with different concentrations of solids dissolved in them, they will be mixed until the concentration is uniform.
But if between these two fluids we interpose a membrane that allows to pass the fluids but not the dissolved solids, the fluid that will move through that membrane will be the one of less concentration. Over time on one side of the membrane, there will be more water content than the other. The difference in height between the two fluids is what is called Osmotic Pressure.
An example could be if a cellophane bag filled with sugar water, sealed it and put it in a container with water. The cellophane bag will serve as a membrane and we can observe how the bag with sugar will be inflating more and more, that has a meaning and is that the water with dissolved solids that is inside the bag does not leave, while the water of the container Without dissolved solids with less concentration will be the one that passes through the membrane (cellophane paper) towards the bag.
Now, if we want to purify water we have to use the opposite process and that process is called reverse osmosis. It is about passing the fluid from the highest concentration to the lowest concentration. This will pass the water leaving the solid matter on the other side of the membrane. If we use a pressure higher than the osmotic, the fluids will end up pressing through the membrane and the solids will be on the other side of the membrane.
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The system of purification by distillation needs to pass through different stages, in each stage a part of the salt water. It is perhaps the most well-known procedure with a more rudimentary basis. Basically in a reservoir seawater is introduced, this is heated to boiling point, heat the water and not the salt will evaporate, rise and subsequently will condense resulting in a high purity water and therefore drinking.
The water that has not been evaporated will therefore have a higher concentration of salt, this operation can be repeated with the rest of water not evaporated, until reaching such saline concentration that ends up forming a totally disposable brine.
In order to obtain potable water from seawater using the freezing technique, only the seawater must be sprayed into a cold chamber with low pressure, ice crystals will form on the salt water droplets. Those crystals are ice; simply by separating that wire by washing you will get drinking water.
Of all it is known that when the sea freezes, the layers of ice that are formed are of fresh water. With the subsequent defrosting of these plates, they become fresh water.
It is one of the most widely used and widespread systems, seawater is introduced in a pulverized form in a low pressure chamber, always below saturation pressure. Some of these droplets are converted into vapor immediately, and then condensed to obtain drinking water. This process can be repeated as many times as necessary until reaching the optimum level of portability.
It is also a method based on crystallization, it is a matter of adhering hydrocarbons to the saline solution to obtain much more complex hydrates and in the form of crystals, washing these crystals can be obtained a free solution of brine. This option is very expensive and complex so it is not commonly used.
It is an electrochemical separation process where the ions are transferred by ion exchange membranes by means of a direct current. A series of cationic and anionic membranes are placed alternately and these in turn will be placed between two electrodes.
Between these electrodes will circulate the water to be purified. These membranes will remain permeable only to the cations or anions, thus limiting the separation of the ions between the electrodes, as a result we will have a demineralized and an ionized current.