The Philadelphia Water Department (PWD) relies upon conventional treatment with ferric chloride coagulation and chlorine disinfection toproduce safe, clean drinking water. Recent regulations such as the Long-Term 2 Enhanced SurfaceWater Treatment Rule and the Stage 2 Disinfectants/Disinfection Byproduct Rule are promptingutilities to further limit the production of disinfection byproducts, namely TTHM and HAA5. This maybe achieved through a change in disinfection practice or through an overall reduction in the amount oftotal organic carbon in the water. Previous pilot studies have investigated the effects advanced oxidationand moving the point of chlorination have on DBP formation. The primary focus of this segment of pilotplant investigations was the use of MIEX, a magnetized ion exchange resin, to reduce total organiccarbon of treated water and, in turn, reduce DBP production.The secondary objectives were to assess the impact of MIEX pretreatment on coagulant/treatmentchemical demand and on filter production. Tertiary considerations included the effects of MIEX onmetals residuals, treatment residuals (sludge) production and chloride to sulfate ratio of the finishedwater.A six-month pilot study was conducted in warm water (May to November 2006) when the potential forDBP production was highest. Water that had been conventionally treated was compared to waterpretreated with MIEX. Performance was evaluated using three coagulants: ferric chloride;polyaluminum chloride; and, aluminum sulfate. Data presented in this paper reflects only the ferricchloride experiments. Capital and operational costs and ease of integration of the existing full-scaleplant are still being evaluated and compared to previously studied alternatives for DBP control. Includes 2 references, tables, figures.
