Brine water produced by the oil and gas industry contains even more dissolved salts than ocean water, and is a growing environmental concern – but scientists have figured out a new way to treat it.
These hypersaline brines can pollute the fresh water resources which communities depend on, and are difficult to treat.
But a team of engineers from Columbia University in the US say they have now developed a radical new approach to desalinating them.
The method, known as "temperature swing solvent extraction" (TSSE), involves mixing the hypersaline brine with an amine solvent.
Scientists say the method can desalinate very high-salinity brines, up to seven times the concentration of seawater. This is more than both the method currently used for seawater desalination, known as reverse osmosis, and the water evaporation method can achieve.
The method was published in the scientific journal Environmental Science & Technology Letters.
Once it is mixed in the brine, the solvent, which is less dense, is lifted to the top of the brine.
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The mix is then placed on a room temperature bath to help complete the water extraction – and after that the solvent is decanted from the mixture.
A warm water bath then provides a temperature swing which de-mixes the processed water from the solvent – because the solvent is less able to hold water at higher temperatures.
When the solvent releases the water, it sinks to the bottom of the bottle – from where it can be collected.