AWWA ACE54462

Many drinking water utilities in the southeastern United States have typically used chlorine and/or chloramines for primary and secondary disinfection. The approaching deadline for implementation of the microbial/disinfection byproducts (M/DBP) cluster of rules has forced some of these utilities to evaluate alternative strategies for compliance. The situation is exacerbated due to the tradeoff between maintaining sufficient levels of inactivation and reducing DBPs. This paper evaluates several alternative strategies for three small to medium surface water systems in South Carolina. All of the utilities evaluated in this paper (Bennettsville - 4.0 million gallons per day [mgd]; Clinton - 6.0 mgd; Orangeburg - 19.0 mgd) use conventional surface water treatment (coagulation, flocculation, sedimentation, dual-media gravity filtration). Each utility uses alum as a primary coagulant and either lime or caustic soda for pH adjustment. Disinfection strategies are evaluated based upon level of pathogen inactivation, reduction of DBP formation, and disinfection chemical costs. Includes 10 references, tables, figures.