Reducing the cost of desalination

24 November 2020

The long-term plan is to use the technology at scale to supplement reverse osmosis plants.

Scientists from the University of Copenhagen, Denmark, have developed a process for converting sea water into drinking water using carbon dioxide. Desalination is used in many countries but it is an energy intensive process.

The new process relies on an alkyl chain-modified diamine treated with carbon dioxide in seawater. The whole process takes place in water and the method ‘can in principle’ remove 99.6% of the salt content of seawater.  ‘We are currently working at 30%-50% reduction, but aiming towards 90,’ the researchers say.  

After salt has been removed from the water, the diamine must be freed from its polymer complex so that it can be used in new cycles of desalination. The researchers say that the desalination process itself does not require any energy inputs, but diamine is costly and must be recovered requiring the precipitate to be heated to 50oC-80oC. The researchers believe that this regeneration process can be improved and made more energy efficient so that it could be used on an industrial scale.

The research team is currently working with a start-up to commercialise the technology at a small scale – in water bottles fitted with special filters. These could be used on life boats or for outdoor activities. The long-term plan is to use the technology at scale to supplement reverse osmosis plants.

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