Magnetic separation in water pollution control - II

Magnetic separation in water purification uses a magnetically susceptible seeding material as a substrate for pollutant removal. The chemical bond between the seed and pollutant is normally achieved by the action of a chemical coagulant. There are cases, however, in which an additive is not necessary, as in the removal of algal cells from sea water. Under the proper chemical conditions, a coagulant cation such as Fe(III) or Al(III) will yield an insoluble precipitate that will form rapidly throughout the solution. This insoluble species coats the solids of the system and is responsible for the bonding that occurs among the particulates. Since the magnetically susceptible seed material is now part of the coagulum that is formed, the subsequent magnetic separation procedure will remove all of the suspended matter as well as the adsorbed precipitate. This removal is rapid and efficient in the magnetic filtration device. The capability of the magnetic separation process to remove the insoluble precipitates and coagulated solids from solution is examined in detail.