Once brine reaches concentrations approaching 30% in the evaporative hedges, almost 90% of the freshwater content will have been removed. At this point the brine will reach concentrations that are too high for continuing the evaporation process. The brine will then be left in salt evaporation ponds and form the basis for ordinary commercial salt production. Salt evaporation ponds, also called salterns or salt pans, are shallow artificial ponds traditionally designed to produce salts from sea water or other brines. The brine from the evaporative hedges in a Sahara Forest Project Facility will be fed into such large ponds and the remaining water will be drawn out through natural evaporation, allowing the salt to be subsequently harvested.
A traditional desalination plants normally extract less than 50% of the available freshwater before returning the brine as a waste product to the sea. The return of water with increased salinity and reduced oxygen content can lead to significant disruptions on often already fragile coastal ecosystems, by creating a habitat unnaturally favorable to species that can tolerate high salinities and by suffocating organisms that reside on the sea floor when heavier oxygen-depleted brine sinks. Moreover, for inland facilities returning brine to the sea represents an additional infrastructural and operational cost, while dumping it on land has unacceptable consequences for groundwater and soil quality. In a Sahara Forest Project Facility we are instead achieving a zero-discharge facility, ending up with salt as a commercial product.