US Patent 7820053 Magnetic separation and seeding to improve ballasted clarification of water

A process for removing fine particles and particulates from water. The process includes mixing a magnetic ballast, flocculant and water to form magnetic floc, and agitating the magnetic floc in a flocculation zone. A portion of the magnetic floc is collected on a magnetic collector in the flocculation zone. Another portion of the magnetic floc is directed downstream to a setting zone where the magnetic floc is settled. The settled magnetic floc is returned upstream of the settling zone where the returned magnetic floc is recombined with other magnetic floc in the flocculation zone. Ultimately, all, or substantially all, of the magnetic floc is removed by one or more magnetic collectors disposed upstream of the settling zone.