AWWA ACE58267

This study evaluated the impact of pre-ozonation before enhanced coagulation and post-ozonation following enhanced coagulation in controlling halogenated disinfection byproduct formation in drinking water. Raw waters from utilities representing each of the nine elements of the enhanced coagulation matrix were examined. All testing was completed using bench-scale, batch experimental procedures. The various waters were analyzed for turbidity, total organic carbon, dissolved organic carbon, ultraviolet absorbance, trihalomethane formation potential and haloacetic acid formation potential. The results indicated that formation of trihalomethanes and haloacetic acids following enhanced coagulation decreased with both pre- and post-ozonation applications relative to the decreases observed by enhanced coagulation alone. The amount of trihalomethanes and haloacetic acids formed were lower for the waters that were pre-ozonated and then coagulated compared to those that were coagulated first and then ozonated. Strong correlations between disinfection byproduct formation potentials and ultraviolet absorbance at 254 nm were observed for enhanced coagulation both with and without pre- and post-ozonation. Includes 16 references, tables, figures.