2. Secondary Pretreatment
Before seawater enters the reverse osmosis filters to remove the salt particles, it must go through a second stage of pretreatment called microfiltration to remove smaller – oftentimes microscopic – impurities. At this point, virtually all impurities other than dissolved salts and minerals have been removed from the water, but it still needs to go through one more step to remove the dissolved salts and minerals to be ready for drinking.
3. Reverse Osmosis Building – The “Heart” of the Plant
The reverse osmosis building is the center of the desalination process, and the Carlsbad Desalination Plant. During this process, dissolved salt and other minerals are separated from the water, making it fit for consumption. The reverse osmosis building contains more than 2,000 pressure vessels housing more than 16,000 reverse osmosis membranes. The pressure vessels were provided by San Diego County-based Protec Arisawa and Dow Water & Process Solutions produced the reverse osmosis membranes.
Reverse osmosis works by pushing water – under intense pressure – though semi-permeable membranes to remove dissolved salts and other impurities. These membranes act like microscopic strainers that allow only water molecules to pass through, leaving behind the salt, minerals and other impurities such as bacteria and viruses.