Evaluating the e ects of granular and membrane filtrations on chlorinedemand in drinking water

In this study, chlorine decay experiments were conducted for the raw water from Nakdong River that is treated by Chilseo WaterTreatment Plant (CWTP) situated in Haman, Korea as well as the e uents from sand and granular activated carbon (GAC) filters ofCWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganiccompounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting (FRA and SRA)organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated e uents from thosefilters contained FRA and SRA that are less reactive and had small reaction rate constants. For the e uents from microfiltration,ultrafiltration, and nanofiltration the chlorine demand because FRA and SRA were further reduced but the reaction rate constants werelarger compared to those of sand and GAC filter e uents. This has implications in the formation of disinfection by products (DBPs).If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential inthe e uents from membrane filtrations could be higher than that in the e uents from granular media filters.