[EricE]

As others point out, it's not a filter since it pushes contaminates away from a particular zone on the membrane, and that zone is where they harvest the fresh water. Flush those contaminates away from the surface of the membrane with contaminated water, clear a new zone of uncontaminated water, harvest, (literally) rinse and repeat.

Nothing to wear out. I'm sure it will require cleaning of some sort (what doesn't) but it sounds like the membranes are designed to be a permanent solution with minimal maintenance. Pretty clever!