We all need water to live and we’re using our fresh water reserves faster than they can be replenished. South Africa knows this all too well, which is why there is an increased interest in desalination. Currently turning seawater into drinkable water is expensive and produces a lot of waste (like brine). Researchers around the world are looking to decrease the cost and waste of desalination systems so we can better manage our local water ecosystems. This month some research came out which proves desalination plants can convert byproducts of the process into on site useful chemicals.
The approach can be used to produce sodium hydroxide, among other products. Otherwise known as caustic soda, sodium hydroxide can be used to pretreat seawater going into the desalination plant. This changes the acidity of the water, which helps to prevent fouling of the membranes used to filter out the salty water—a major cause of interruptions and failures in typical reverse osmosis desalination plants.
“The desalination industry itself uses quite a lot of it,” Kumar says of sodium hydroxide. “They’re buying it, spending money on it. So if you can make it in situ at the plant, that could be a big advantage.” The amount needed in the plants themselves is far less than the total that could be produced from the brine, so there is also potential for it to be a saleable product.