The process of desalination, or purifying saltwater, creates more waste water than potable water, according to a new report published in the journal Science of the Total Environment.
But since desalination plants provide a critical source of drinking water for people around the world, the number of operating facilities is likely to significantly increase in the years ahead, especially as demand for water increases and fresh water availability diminishes, according to AFP.
"There is an urgent need to make desalination technologies more affordable and extend them to low-income and lower-middle income countries,” Vladimir Smakhtin, a co-author of the paper from the UN University, told the BBC. “At the same time, though, we have to address potentially severe downsides of desalination, the harm of brine and chemical pollution to the marine environment and human health.”
The authors of the report found that for every 1 gallon of fresh water that desalination produces, 1.41 gallons of toxic brine are created. More than 50 billion cubic meters (or more than 13.2 trillion gallons) of toxic brine are generated in this way each year, enough to cover the state of Florida with a layer of salty slurry.
The vast majority of this sludge is dumped directly into oceans, where it can create dead zones devoid of oxygen, or on land where it destroys plant and other life and contaminates groundwater supplies.
Not only is this brine hyper-saturated with salt, but it also contains substances used to desalinate water such as copper and chlorine.
The countries with the highest concentration of desalination plants are in the Middle East, especially in wealthy countries that have little access to freshwater. In fact, 90% of desalination plants exist in wealthy countries, reflecting the enormous costs involved in creating the plants and then operating them.
Saudi Arabia and the United Arab Emirates alone account for more than 42% of the brine created from desalination plants.
While desalination provides crucial temporary relief from water scarcity, the process could endanger countries in the long-term.
Around the world, more than 2 billion people lack reliable access to safe drinking water, and 3 billion people face water scarcity.
Demand for water is expected to increase by 40% by 2050, as the global population surges by more than 2 billion, according to the United Nations.
At the same time, freshwater supplies will diminish as industrial pollution contaminates existing sources of water, countries overdraw rivers and aquifers, and climate change drys large swaths of the planet.
As a result, “at least 1 in 4 people will live in a country where the lack of fresh water will be chronic or recurrent,” Antonio Guterres, the UN Secretary-General, said in a statement.
“The growing water crisis should be much higher on the world’s radar,” he added.
The urgency of this crisis is already upon many countries. Cape Town nearly became the first major city to run out of water in 2018, and Sao Paulo is continually on the verge of draining its water supplies.
Against this backdrop, desalination plants may come to play an even greater role than they do today. Nearly 2,000 more facilitated are expected to come online by 2025, according to the report.
Finding a way to better manage the byproduct of toxic brine will be essential.
"The good news is that efforts have been made in recent years and, with continuing technology refinement and improving economic affordability, we see a positive and promising outlook,” Smakhtin, the co-author, told the BBC.