Desalination will be essential to meet the water needs of many areas around the world as an alternative to overextended or depleted fresh water sources. For example, Sydney, Australia, has recently restarted its 10-year old desal plant project in January 2019 because of extended drought conditions.
One of the complications associated with desalination, beyond its high cost and huge energy expenditure, has been disposal of the associated brine.
The expected environmental impact of discharging the resulting brine back into the ocean has been a major focus of objections to permitting desal plants. At one coastal California location, the project sponsor had to agree to complex and expensive diffusers to address concerns that the brine discharge would create a dead zone near the discharge pipe.
An article in the journal Environmental Science & Technology recently reported on a seven-year study of the Sydney, Australia, desal plant, which is one of the largest in the world. Surprisingly, the article concluded that the hypersaline discharge substantially increased both the abundance of fish and the diversity of species.
The report hypothesized that the fish were responding to "turbulence created by dynamic mixing associated with the high-pressure release of the brine," but said more research was required. In any event, it appears that the brine was not immediately toxic, which could be great news for coastal cities around the world that may soon need to address continuing water shortages.