Effects of Hypersaline Desalination Brine Discharges: There Are Environmental and Ecosystem Effects: The Arabian Gulf is Susceptible Due to Weak Waves and Less Freshwater Input

     Desalination plants produce waste brine, hypersaline (super-salty) water rich in chlorides and other components, including FeCl3, NaOCl, AlCl3, and H2SO4 (sulfuric acid). The different chemicals come from different processes of the plant. In most cases, the waste brine is simply released back into the sea. Typically, for every liter of freshwater produced, there is 1.5 liters of waste brine produced. The concentration of these brines is in the range of 60,000 to 70,000 parts per million (ppm). Desalination plants are common in the Middle East, where freshwater resources can be scarce. The Arabian Gulf is shallow and lacks strong currents, and freshwater flowing into it has been reduced due to upstream dams and diversions. Saltwater from the oil & gas industry also makes its way to the Arabian Sea. The Gulf is now about 25% saltier than typical seawater, with hotspots double or triple its regular salinity. This also means that desalination will have to work harder to remove the extra salts from the water, which will in turn create even saltier waste brine.

     Most desalination plants rely on reverse osmosis to remove the salts. The resulting waste brine also typically contains additives such as antiscalants and coagulants. It is denser than the seawater it is discharged into, which makes it sink to the bottom of the sea and spread out over the seafloor. This can have significant impacts on benthic organisms, including bacteria, seagrasses, polychaetes, and corals. Seagrass, which is normally salt-tolerant, is often killed by hypersaline water. This is not desirable since seagrass has well-known environmental benefits. The high salinity, as well as the antiscalants, can negatively affect corals, leading to partial bleaching. The symbiotic species that cling to coral are also reduced significantly by the waste brine.

     There are other environmental impacts of desalination plants, including the trapping of many aquatic organisms through the intakes. This adds to the waste brine effects to lower the richness of marine organisms near the plants. Benthic organisms may be significantly affected in coastal areas near the brine discharge outfalls.

     Rich countries like the UAE and Israel have the most desalination capacity. Multiple plants from the Gulf states can combine to degrade seawater quality in a region such as the Arabian Gulf.

     The article in Climate Compass notes that desalination projects are set to grow significantly over the coming years.

“The global desalination market is expected to grow at a compound annual rate of 9.8 percent, with an increase from US$15.2 billion in 2022 to US$22.5 billion in 2026. Investment is accelerating fast. The global water desalination market was recorded at USD 20.32 billion in 2023, and is expected to reach up to USD 44.57 billion in 2032, with a compound annual growth rate of 9.12 percent forecast for the period 2024 to 2032.”

     They note that site selection for discharge is a key factor for reducing impacts. They also note that more monitoring should be implemented to minimize environmental and ecosystem impacts.

“A clear consensus across many reviewed scientific articles is that discharge site selection is the primary factor that determines the extent of ecological impacts of desalination plants. Ecological monitoring studies have found variable effects ranging from no significant impacts to benthic communities, through to widespread alterations to community structure in seagrass, coral reef, and soft-sediment ecosystems when discharges are released to poorly flushed environments. The science is telling regulators exactly what they need to know.”

“The urgency of rethinking brine management is clear, with integrated approaches needed that balance water security with resource efficiency in a water-constrained world. The industry is growing faster than the rules designed to govern it, and the gap between the rate of expansion and the pace of environmental monitoring continues to widen in most of the world's most water-stressed regions.”

 

  

 

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Desalination's dark side: Why it might not be the silver bullet we hoped for. Jeff Blaumberg. Climate Compass. March 7, 2026. Desalination's dark side: Why it might not be the silver bullet we hoped for