Securing water supply: A balancing act

Reduce, reuse, recycle: the solution to the water scarcity crisis we face as agriculture, industry and private homes all compete for the valuable commodity. See how Linde alleviates this conflict of interests - with CO₂ and SOLVOCARB®

Water Treatment Key Visual No. 2
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Water: Something we take for granted. Now it’s about securing supply through recycling.

In the vast, arid deserts that dominate the Middle East, every drop of water counts. Yet the Arab states surrounding the Persian Gulf record some of the highest levels of water consumption per capita in the world. In Saudi Arabia for example, that figure is reported to be 265 litres per day: double the EU average. Population growth, rising living standards and a rapid expansion of industry have meant overexploitation of the region’s non-renewable groundwater resources, resulting in what is considered one of the most complex water crises in the world.

Indeed, with some experts predicting that Saudi Arabia’s groundwater could dry up in less than 15 years, reuse is the key to securing water supply for private homes, industry and agriculture alike: not only in the Kingdom, but the wider Middle East region and throughout the whole world. That’s where Linde can help.

Achieving water reuse: It’s takes a certain chemistry

At the heart of any water treatment is balanced water chemistry. The pH value must be just right for whatever the application: whether drinking or industrial processes. Too alkaline and not only is it undrinkable but it will affect infrastructure through scaling and if the pH is too low then corrosion damage can occur. This is why Linde developed the SOLVOCARB® system – a reliable, eco-friendly way to accurately neutralise the alkaline pH value of water using carbon dioxide (CO2). Reliability and ecology are particularly important in the desalination process: where fresh water is obtained from seawater – one means of lessening the demand on groundwater.

“Everything is pointing towards desalination,” confirms Darren Gurney from the Linde Global Development Centre. Gurney is a water treatment expert who has seen countless desalination plants go on stream in the last few years – due in no small part to Linde’s SOLVOCARB® system.

After adding important substances such as calcium oxide (lime) to improve the hardness of the raw desalinated water (known as re-mineralisation), the pH is then corrected to place it in the range required by the regulations for drinking water or industrial process requirements. This is achieved by adding CO2.

“The costs per cubic metre of treating water have dropped significantly in the last 15 years,” reports Gurney, adding that this has less to do with energy prices and more to do with technology and continued innovation. Owing to the shortage of groundwater, the Middle East is now home to 70% of the world’s desalination plants. In Oman, for example, Linde’s SOLVOCARB® system will be used in Suez’s new desalination facility in Barka, which, with a capacity of 281,000 m3 per day is the country’s biggest reverse osmosis drinking water project. It will start supplying the Sultanate with drinking water by 1 April 2018. 

Over time, SOLVOCARB® has become more and more efficient, opening up new opportunities and expanding the application spectrum. As a result, companies are increasingly turning to CO2 and SOLVOCARB® to treat water for industrial purposes.

At the centre is the Arabian Peninsula, mainly comprising Saudi Arabia, bordered on the left by the Red Sea and on the right by the Persian Gulf and the Arabian Sea
The Persian Gulf: An oasis in the desert – one whose days are numbered. The region must reuse water – and Linde is there to help.
SOLVOCARB reactor for raw water treatment. This picture was used in the water treatment brochure (ID: 114996)
The SOLVOCARB® reactor at the Riyadh Refinery Plant

Taking the ‘waste’ out of industrial wastewater

While water may be scarce in the Gulf region, crude oil reserves certainly aren’t. That is why the region is the petrochemical centre of the world – a title which unfortunately places even more demands on water. The industry uses huge amounts of the precious resource: refineries, for instance, discharge approximately one-half to one barrel of wastewater for every barrel of crude oil that is processed.

For companies like Aramco – the Saudi Arabian Oil Company – transporting desalinated water to meet its plant requirements is becoming cost-prohibitive and extraction of non-renewable groundwater is no longer an option. This led the company to explore sustainable solutions that would allow wastewater reuse. At Aramco’s Riyadh Refinery Plant, Linde’s SOLVOCARB® system is pivotal in such a solution.

Before the wastewater can be reused, it must be softened using the lime soda process, resulting in an alkali raw water. The SOLVOCARB® reactor lowers the pH from approximately 11.5 to between 7.8 to 7.0 (target pH ~ 7.5) by adding CO2. The water can then go through further treatment processes like filtration, reverse osmosis and demineralisation before being used in boilers, product make-up and cooling towers.

The SOLVOCARB® reactor in this case replaced an old diesel powered system for generating CO2, so not only is it more efficient for the customer but it also significantly shrinks the environmental footprint.

Just a drop in the ocean?

Looking forward, there is hope for the region’s water situation – thanks to measures taken by governments as well as advancing water treatment technologies. In the face of an ever-increasing demand, Saudi Arabia, for example, has pledged to achieve 100% wastewater reuse from cities with 5,000 inhabitants or more by 2025 and is committing over $66 billion in long-term capital investments for water and sanitation projects over the next 10 years. While SOLVOCARB® alone will not be able to redress the balance, the Linde system is certainly part of the solution.