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This paper discusses how Metropolitan San Juan, Puerto Rico embarked on a study to enhance treatment in terms of improved coagulation-flocculation-sedimentation using an innovative process in treating its highly variable source waters. The study was designed in assessing the effectiveness of sand ballasted/Actiflo coagulation, an innovative process to conventional coagulation in terms of organic (measured as DOC) and particulate (measured as turbidity) removal. Evaluations were conducted in both bench and pilot-scale mode using conventional (FeCl3 and alum) as well as alternative (PACl) coagulant. The bench-scale study also included a detailed characterization of the seasonal water quality variations in terms of inorganic (basic water quality) and organic (molecular weight and hydrophobic/hydrophilic fractionation) water qualities. Source water characterizations provided insight into seasonal variability and also insight into understanding the effectiveness of treatment processes and to relating them to plant performance. The three water treatment plants that serve the Metropolitan San Juan area rely on four different surface water sources. All of these four sources were sampled over a one-year period (2000-2001) to capture three different seasonal conditions. These are: pre-hurricane to correspond to a before the hurricane/dry season; during-hurricane (specifically Hurricane Debbi in August 2000), to correspond to a hurricane /wet season; and, post-hurricane, to correspond to a second after hurricane/dry season. Thus, a total of twelve samples (four sources at three seasonal conditions) were received for the bench-scale studies for water quality characterization and treatability studies. Bench-scale studies were performed at the University of Colorado (CU) to parallel pilot-scale studies constructed at the Sergio Cuevas WTP site. Pilot tests consisted of testing both conventional as well as sand ballasted mode using both conventional and alternative coagulant during the pre-hurricane/dry, hurricane/wet and post-hurricane/dry season to compare the effectiveness of the coagulation process (conventional versus sand ballasted mode) and coagulant (FeCl3, alum and PACl) type for organic and particulate matter removal. Includes tables, figures.

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Edition: Vol. - No. Published: 11/01/2002 Number of Pages: 17File Size: 1 file , 460 KB