For decades, the region has depended on the process of desalination, and the steel on which its structures rely, to deliver vital freshwater to its citizens.
And this is a global industry – to date, more than 17,000 desalination plants have been contracted to deliver usable water to 174 countries worldwide. The plants remove salt and minerals from seawater, rendering it fit for human consumption and agricultural use.
The Middle East accounts for more than 60% of this desalination capacity, and its largest country, Saudi Arabia, produces more desalinated water than any other.
Stainless steel, with its corrosion-resistant properties, is the material of choice in the construction of both thermal distillation and reverse osmosis plants.
How does desalination work?
Modern desalination plants typically use one of two processes – thermal distillation or reverse osmosis – and steel lies at the core of both types of operation.
Through each process, piped seawater is split into treated water and a salt concentrate with a higher salinity than raw seawater. Thermal distillation, which mimics the water cycle, uses heat to evaporate and condense water in order to purify it. In reverse osmosis plants, saltwater is forced through a membrane at high pressure using pumps, allowing water to pass through while blocking salts and other mineral solids.
Stainless steel, with its corrosion-resistant properties, is the material of choice in the construction of both types of plants. Its high durability and low maintenance requirements have made it integral to the desalination industry’s success.
Newer thermal desalination plants are typically built using duplex stainless steel – such as grades 2205 and 2304, which contain molybdenum – for corrosion resistance. The innate mechanical strength of the duplex stainless steel means less is needed, enabling the overall density and weight of desalination plant evaporators to be reduced by up to 30% and making it more economical.
At seawater reverse osmosis plants, the use of stainless steel containing 6% molybdenum, and super duplex stainless steels such as the grade 2507 used in Israel’s Ashkelon plant, has also kept corrosion at bay.
While desalination technology has continued to evolve, steel has remained the industry’s reliable and resilient constant
A new ‘green’ solution
Though essential to the Middle East’s drinking water supply, the energy-intensive desalination industry is renowned for its large carbon footprint. But, new desalination innovations may help to make the industry greener.
In January 2020, Saudi Arabia appointed UK-based enterprise, Solar Water Plc, to construct its first solar dome desalination plant in NEOM, a new development in the country’s northwest.
In Solar Water’s solar dome concept, seawater flows into a hydrological dome built of steel and glass. By using parabolic mirrors to concentrate solar radiation onto the steel frame and glass structure, the company believes its innovation has the power to create a “constant water cycle” within the dome, equivalent to “up to 20,000 suns”. Here, both the corrosive-resistance and superheat conductive properties of steel are vital to success.
While desalination technology has continued to evolve, steel has remained the industry’s reliable and resilient constant. And with the advent of renewably-powered solutions, its important role as an affordable, robust, and highly recyclable facet of potable water production looks set to continue.
Video: EWT-World Company, 21:12 Communications for Solar Water