Engineers from MIT have devised a new approach for turning desalination waste into useful chemicals.
Modern desalination processes often leave behind a lot of highly concentrated brine, which is usually disposed of by dumping it back into the sea.
This process requires costly pumping systems which have to be managed carefully to prevent damage to marine ecosystems.
Now researchers from MIT have come up with several new processes to turn brine into useful chemicals – including ones that can make the desalination process itself more efficient.
One of their approaches involves creating sodium hydroxide. Also 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,” opines team lead and professor Amit Kumar, alluding to the production 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.
Another important chemical used by desalination plants and many other industrial processes is hydrochloric acid, which the researchers say can also easily be made on site from the waste brine.
The chemical can be used for cleaning parts of the desalination plant, but is also widely used in chemical production and as a source of hydrogen.
Image and content: MIT
