Indeed, the Ancient Mariner’s lament about his raging thirst amid an abundance of undrinkable seawater could gradually become a thing of the past as improvements to desalination technology enable the large-scale removal of salts and minerals from the ocean But, there is a hitch: How to turn this abundant resource into drinking water without harming life in the sea and adjoining coastal environment because of the growing torrent of brine water and chemical pollution from nearly 16,000 desalination plants scattered around the globe.
A study published on 14 January by United Nations’ water researchers says there has been an “exponential increase” in global desalination capacity compared to 20 years ago — and a concomitant increase in the flow of polluted, hyper-salty brine water into the ocean.
While the biggest plants are located in the Middle East, North Africa, Spain and small island nations, the study estimates that there are now 15,906 desalination plants operating in 177 countries (with more than 300 in Sub-Saharan Africa).
And while removing salt from seawater remains a costly option compared with more conventional sources such as damming up rivers, the authors say desalination has vast potential if the power-generation costs and growing environmental concerns can be addressed.
The effluent can also contain toxic chemicals from antiscalants and antifoulants that are used in the desalination and filtration process (including copper and chlorine).
“Since seawater reverse osmosis effluents are growing in volume, our lack of full understanding of their long-term impacts demands more, not less, caution,” according to researchers Dr Nurit Kress and Bella Galil.
They point instead to an increasing body of research and case studies in the Middle East, Australia and California showing that brine effluents impact marine life in the vicinity of outfall pipes, including seagrasses and corals that serve as a nursery area for fish.
While Israeli legislation requires an EIA as part of the planning of a desalination plant, Kress says the true structure of some chemical treatments are not disclosed and no effluent toxicity tests are required.
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