AWWA JAW65738

Coagulant choice is driven by a number of factors, including removal performance, chemical supply, and chemical cost. In most cases, the properties of the flocs that form downstream are given little consideration. This article presents floc structural data obtained during the coagulation of a water source rich in natural organic matter (NOM) under optimum conditions for a range of coagulant systems. The evaluation of floc structure includes traditional coagulants such as ferric sulfate and alum. In addition, given the recent emphasis on improving NOM removal, flocs formed from more novel treatment options such as polymers and ion exchange resin pretreatment were investigated. The authors offer a rigorous comparison of NOM flocs formed from different coagulants by measuring key structural parameters. This article provides water managers with important information for deciding which coagulant should be used during the treatment of waters containing high concentrations of NOM. Includes 41 references, tables, figures.