Neom, the smart city of the future built from scratch in the Saudi desert, will quench its thirst with desalinated sea water and will do so with zero impactas was announced this summer, opening entirely new perspectives for the spread of desalinators around the world.
For some time now, the challenge has been to make desalination ever cheaper and greener. In the first place, sustainability passes through the use of renewable energy, since these are plants with a high energy consumption. Desalination carried out with renewable energies is one of the main challenges for the future of countries subject to water scarcity and arid areas, where desalinators are most used, they are also those with the greatest solar radiation and therefore more suitable for photovoltaics. But technology always offers new possibilities as shown by the case of the Canary Islands where local authorities have signed an agreement with the Norwegian Ocean Oasis for the construction of a desalinator that will be placed directly in the sea to exploit the energy produced by the waves.
M.the issue that requires more attention from an environmental point of view is the disposal of production residues, the so-called brine, which contains a high concentration of salts. Today, around 100 billion liters of desalination water is produced in the world every day, resulting in a similar mass in terms of saline residues. Their disposal in the sea involves a considerable cost in terms of energy and a strong attention to the impact they can cause on the environment because the brine is not polluting but if it is discharged into the sea in large quantities and in the absence of strong currents that can disperse it quickly. it can cause an increase in water salinity, with negative effects on the marine ecosystem.
In the Netherlands, with funding from the European Union, the Zero Brine (zero brine) pilot projects have redesigned the brine treatment scheme from a linear to a circular model to recover minerals, salts and demineralized water. In America, engineers at MIT in Boston have also studied a way to treat desalination waste by converting it into useful chemicals, including those that can make the desalination process more efficient.
All this is becoming reality in Neom, the city that wants to be a world example of innovation and environmental sustainability. Here it will be built a desalinator that in 2025 will produce one million cubic meters of drinking water per day, but already from next year it will be in operation with a capacity equal to one third of the total. For the first time in the world, the energy supply will be guaranteed by green hydrogen, i.e. produced in turn with renewable energies. The plant will use innovative membrane separation technologies to produce concentrated water and brine streams. The brine generated by the plant will be treated to feed industries that use raw materials of high purity industrial salt, bromine, boron, potassium, gypsum, magnesium and rare metals. The brine therefore becomes a product and no longer a waste.
Also in Italy research centers such as the Clean Water Center of the Polytechnic of Turin or companies specialized in water treatment such as Fisia Italimpianti (Webuild Group) are working to improve the cost and environmental impact performance of desalination plants, plants that according to Webuild could ensure to our country a structural solution to the water crises that climate change will aggravate in the coming years. The Group also presented a project, called ‘Water for life’, which with the construction of 15-16 plants throughout Italy could definitively solve the problem of future water crises.