Commonly Used Coagulants:
The most commonly used water treatment coagulant is based primarily on Aluminium or Iron salts. Lime is used as secondary coagulants in drinking water treatment but as a primary coagulant in waste water treatment. In certain cases, polyelectrolytes are used as coagulant.
The reaction of coagulants in water and waste water are well-known in water chemistry and some of these are reproduced here for the ease of reference.