The world thirsts for clean water. But some parts of the globe get little rain, and fresh water lakes and streams aren’t available. Scientists and engineers have a way to make saltwater fresh. But it’s expensive—cost-wise, energy-wise, and now some say environment-wise too. Are desalination problems too big to ignore?
Water is important for human survival. That’s because God made the body to use water in every cell, tissue, and organ. Without rain or fresh water sources, people in dry regions—like North Africa or the Middle East—must consider other options. One is desalination.
Desalination removes minerals from saltwater. The process, sometimes called “desal,” makes water usable for drinking or plant irrigation. Most desalination plants work by forcing saltwater through a membrane at high pressure. The membrane separates the water from salt and other substances. (For more information on the process and a desal plant in California, read “Testing Salty Waters” at teen.wng.org/node/2494)
Good news, right? There’s a problem: Freshwater isn’t the only thing coming out of desalination plants. The process also produces brine, a super-salty concentrate.
The world’s nearly 16,000 desal plants produce almost 142 million liters of brine each day. That’s much more than previous studies had estimated, says Manzoor Qadir of United Nations University’s Institute for Water, Environment, and Health. In fact, Qadir says that’s enough brine to swamp an area the size of Florida under a foot of salty water.
Qadir and other researchers from Canada, the Netherlands, and South Korea published “The State of Desalination and Brine Production: A Global Outlook” in January. The study warns that most desal plants produce more brine than drinkable water—about 50% more.
It gets worse. Desalination engineers add chemicals like copper and chlorine to the saltwater in order to control the growth of bacteria. Those chemicals often end up in the brine and can be toxic to sea life. Much of that brine is dumped untreated into the ocean.
Some researchers think scientists exaggerate fears about desal wastewater. They cite studies showing how brine can aid crops of salt-tolerant fish. They point to miners who are able to extract important chemical elements from brine—such as iodine and magnesium. Still, most of them are calling for better brine management.
Qadir hopes his study will “raise awareness” of how much brine comes out of desal plants. Phillip Roberts, a water resources engineer, thinks volume isn’t the problem. Instead, he says, “How it’s disposed of is what matters.” And he believes, “We can dispose of it safely.”