Can you just not let it dry up a little bit more and sell it as sea-salt? I suspect it's not that easy, but on the other hand, the Bay Area has lots of "salt fields" where seawater is dried into useable salt.
The issue is that it's not just salt, but contains many other minerals and contaminants.
Probably better to just dump it on the surface of the desert and let it dry up.
Dump it in the ocean? It's not like we're extracting water in sufficient quantities to affect the salinity of the Mediterranean.
The issue there is with the mixing rates. While we won't affect the overall average dumping will create local zones of increased salinity, which can be a problem.
I remember reading the problem is that the salinity of the local dumping area rises sharply (maybe killing marine life)