Who says its impossible to send them all back ? Lets do a little math...
Ocean going cargo ship
http://en.wikipedia.org/wiki/Cargo_ship
Simple math:
Assuming an "average" cargo ship capacity of 100,000 Tonns
Assuming an average cargo unit item of 200lbs
(100,000 tonns * 2000lbs/tonn) / 200lbs per unit = 1,000,000 units / per ship
All aboard !
Our most dangerous enemy lives among us.