For that size in one ...

For that size in one location I believe it would be far more cost effective and maybe even faster to go for a custom designed plant.

If not already being done, I also recommend you immediately sample and analyse sea water quality, at least weekly, ideally for 12 months, and commence pre-treatment jar testing trials. You could also consider commencing intake construction - preferably using beach infiltration gallery or Neodren system http://www.catalanadeperforacions.com/en/neodren capable of ~500L/s and perhaps consider construction of the brine discharge capable of ~300 L/s with the same contractor/equipment.

Feel free to contact me directly if any more support required.