PRE-POLYMERIZED INORGANIC COAGULANTS AND PHOSPHORUS REMOVAL BY COAGULATION - A REVIEW

This paper reviews the use of pn-polymerised inorganic coagulants in w ater and waste-water treatment, and discusses the removal of phosphoru s by chemical precipitation and coagulation. Commonly used inorganic c oagulants are aluminium or iron (IU) based salts, but a range of hydro lysed Al/Fe species. and not re Al/Fe salt itself, are responsible for the removal of impurities from water. By the development and use of p olymeric inorganic coagulants, the coagulation performance can be impr oved significantly in some cases. Chemical precipitation and coagulati on in phosphorus removal are two different processes. with the former related to the compound solubility acid the latter depending on the de stabilisation-adsorption mechanism. Presently, there is uncertainty co ncerning the mechanisms and overall performance of phosphorus removal by pre-polymerised metal coagulants.