What Various Types of Coagulants are Used?
The most common coagulants are iron and alumunium salts such as ferric sulphate, ferric chloride, alumunium sulphate (alum) and sodium aluminate. Ferric and alumina ions each have three positive charges and therefore their effectiveness is related their ability to react with the negatively charged colloidal particles. With proper use these coagulants form a floc in the water which serves as a kind of net for collecting suspended matter. In recent years synthetic materials called plyelectro-lytes have been developed for coagulation purposes. these consist of long chain like meolecules with positive charges. In some cases organic polymers and special types of clay are used in the coagulation in making the floc heavier, causing it to settle out more rapidly.
