Evaluating the Efficiency of Coagulants Mixture (Alum and Ferric Chloride) in Minimizing the Turbidity and TOC Colloidal in Drinking Water Treatment Units

Abstract

In this paper jar tests were done on fresh water (river water) taken from AL-Jadriya / Baghdad drinking water treatment plant to examine two coagulant mixtures (alum and ferric chloride) at several percentages (0, 25, 50, 75 and 100%). Ferric chloride has been used to remove turbidity using NTU (Nephelometric Turbidity Units) and total organic carbon (TOC). A 95.4% removal of NTU at 25mg/L dose at 25% coagulant mixture obtained, while for alum alone the result was 94.8% NTU (0.6% difference) and 68.7%,and 62.5% TOC removal for a mixture of 25% and 50% respectively, higher than 56.2% for alum alone and increased the results to a significant difference of 12.5% and 6.3% for TOC removal. This means that using a mixture of coagulants enhances their performance to higher than each one alone.