I have given this some more though. Desalination aims to produce...

I have given this some more though. Desalination aims to produce fresh water. It produces fresh water and a concentrated brine which typically is pumped out to sea. I would guess the initial concentration phase of the parkway process would use membranes like most desalination plants. The proprietary tech would come in the stage they produce salt, lime, caustic soda and the petrochemical residues.
The only problem I can imagine this might create is that the salt and lime are only going to be marginally profitable, they are readily available from existing sources. The petrochemicals probably wont be significant. So the economics rely on caustic soda. If there is a process to produce caustic soda from concentrated brines profitably it would if widely adopted bring the price for this commodity down.