Water Technologies > Case Studies > Port pollution, Algeria

Tracking the salty brine dispersion in sea water subsequent to desalination


Overview: Sea water has in average a salinity of about 3.5%. Sea water desalination involves the removal of salts and other impurities from sea water by using specific membrane processes or by vaporizing sea water to produce fresh water. But this transformation process into fresh water carries the risk of increased salinity of coastal water. This is mostly due to the highly saline brine that is rejected into the sea, with a potential increase in temperature, contains residual chemicals from the pretreatment process, heavy metals from corrosion or intermittently used cleaning agents.

The challenge: The challenge posed to the engineers is to minimize the highly-concentrated brine pollution of sea waters, more precisely, the long-term impacts of brine disposal on the marine environment. Twice as saline as the ocean, the brine is denser than the waters into which it is discharged and tends to sink and slowly spread along the ocean floor. Efficient methods are sought to disperse concentrated brine, such as multi-port diffusers placed on the discharge pipe to promote mixing. The role of simulation is important at this stage.

TransAT Solution: With the advanced turbulence modelling and the meshing technique of immersed surfaces, TransAT is capable to resolve the flow-field along complex, irregular shape of the bay. Thanks to Block Mesh Refinement feature available in the code, the computational grid can be refined near the port docks, which allows reducing computational time significantly. With the use of mixture multiphase model, the flow can be accurately captured, including the brine dispersion in sea, and the water temperature. Such information is needed for the design of brine dispersion mechanisms, if needed.

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ASCOMP Switzerland
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