Brine doesn't necessarily behave the way you imagine.
https://en.wikipedia.org/wiki/Brinicle
https://en.wikipedia.org/wiki/Brine_pool
Blue Planet video of a brinicle, content warning for kind of horrifying death of sea creatures: https://www.youtube.com/watch?v=lAupJzH31tc
You can dilute the brine in a facility before disposing.
Blue Planet video of a brinicle, content warning for kind of horrifying death of sea creatures: https://www.youtube.com/watch?v=lAupJzH31tc