To begin with…

As we know safe drinking water is an essential human need. Water in general exists all over the world but the vast majority of it is salty containing microorganisms like dissolved solids and it is unsafe for consumption and even for domestic use. Humanity was curious enough to have developed desalination techniques for converting sea water into safe water for domestic use. Nowadays with innovative methods we are able to generate clean and safe drinking water out of sea water!

So what is desalination?

In basic terms, desalination is a process that turns briny (salty) water – anything from brackish inland groundwater to seawater- into fresh drinking water by removing salt, impurities, and contaminants. As we previously mentioned desalination has been around for decades and already provides an alternative water supply in many parts of the world, with an estimated global production of almost 30 billion gallons of treated water per day in 2019. There are two main methods to large-scale desalination for drinking water: (1) thermal distillation (evaporation), which is still widely used in areas like the Middle East where energy is often cheap or subsidized and (2) more modern reverse osmosis (membrane separation) technologies.

What is the process of desalination?

As we saw briefly in previous blog posts, to start the process of desalination the plants have to first remove all the possible microorganisms that might have contaminated the water. This process is really important as these contaminants can interfere with the desalination process. This phase is called filtration and it can be done with mostly two methods. The plants use coagulation and filtration with membranes while adding chlorine to reduce the risk of membrane fouling before the treatment starts.

Of course, the process does not stop there. Even after the filtration and the desalination the water is still not suitable for consumption as it is missing many of its core elements. The next process is called Conditioning. Conditioning is needed to add back alkalinity with some minerals like magnesium and calcium (remineralization), often by blending with a different treated water source (e.g., imported water). Remineralization also improves the stability and compatibility of desalinated water with blending water. It is also necessary to ensure an adequate level of residual chlorine disinfectant to provide lasting public health protection from waterborne pathogens.

Can we draw a conclusion?

Over the last several decades, steady advances in conventional treatment of freshwater sources like rivers, lakes, and deep groundwater aquifers have enabled us to maximize their use. However, in areas where readily available freshwater fails to meet our needs, such as some rapidly growing coastal regions, the demand for “creating” new freshwater from saltwater (and water reuse) will only increase. Desalination technologies are poised to benefit from accelerated research investments and innovations to make it even more cost effective.

So it remains to be seen how much of that technology will be brought into wide effect in the coming years.


Evangelos Gkougkoutoudis, International Business Development, OTS