The key behind the ballasted flocculation process is the use of continuously recycled ballast or fine sand, which attaches to flocculated particles through a polymer bridge. Very high settling velocities combined with rapid flocculation kinetics lead to plant footprints less than 1/10th of conventional treatment processes. This paper reviews the background theory associated with ballasted flocculation and presents the process approach and performance results from a filter backwash recovery installation. Includes 6 references, tables, figures.