ENHANCED COAGULATION USING AL FE(III) COAGULANTS - EFFECT OF COAGULANT CHEMISTRY ON THE REMOVAL OF COLOR-CAUSING NOM/

The addition of excess coagulant and lowering the coagulation pH in or der to improve the removal of NOM and DBP precursors have been defined as 'enhanced coagulation'. However, as a consequence, sludge producti on and treatment costs are increased, and the chemical storage and fee d facilities need to be changed. Through developments in coagulant che mistry, various types of pre-polymerised coagulants have been prepared in recent years and been applied widely. In comparison to conventiona l coagulants under such 'enhanced coagulation' conditions, pre-polymer ised coagulants can improve NOM and THMFP removals at relatively lower dosages. In addition, this results in a reduction in the sludge produ ction and treatment costs, and the existing facilities in a water trea tment works need not be changed by the use of pre-polymerised coagulan ts.