Dear Assia
Saline water is not commonly found in desert areas. Typically such water is highly brackish and is treated by brackish water reverse osmosis systems. The concetrate is ususally disposed to deeper aquifers not hydraulically connected to the brackish water aquifer. Not every desertous location has brackish water aqufers. Often these aquifers are very limited in size and recover very slowly - therefore they are not commonly used as water supply sources.
Nikolay Voutchkov
The brackish water can be treated using hybrid desalination techniques ( a combination of two or more techniques)to recover maximum fresh water and to recover salts in solid form and to achieve zero discharge.High temperatue and good wind velocity of the desert will help the process.
Mr. Nikolay has rightly commented. Desert areas have brackish water of varying degree of concentration. At places brackish water is usable for agriculture too. Treatment of brackish water is possible through various means but not economic in most cases.