This article discusses how desalination plants pour toxic brine back into the oceans. The salt and chemicals in the brine left over from desalination can threaten local marine ecosystems.
Because brine discharge had not been reported comprehensively, Qadir and his colleagues looked at the recovery ratios for various combinations of water types and desalination technologies in the scientific literature. They also looked at salt levels in the water going into and coming out of the small number of plants for which such data could be found. From these data points they were able to calculate the average recovery ratios for more than 80 percent of the desalinated water produced worldwide. They found that instead of creating one liter of brine for every liter of freshwater produced, as had generally been assumed, desalination on average has a ratio closer to 1.5 to 1. The researchers’ U.N.-backed study was published in December in Science of the Total Environment.