Secondary effects of enhanced coagulation and softening

Abstract

Enhanced coagulation and softening—while reducing the formation of DBPs—have secondary effects on water treatment processes that must be considered. The implementation of enhanced coagulation or enhanced softening, while reducing the formation of disinfection by‐products, will affect other treatment processes as a result of the associated changes in water chemistry and solids loading. Utilities that implement enhanced coagulation or softening will likely see secondary effects, which need to be anticipated and mitigated. The AWWA Water Industry Technical Action Fund sponsored an expert workshop with representatives from the utility, consulting, academic, and regulatory fields to identify and characterize the secondary effects of enhanced coagulation and softening and to recommend mitigation strategies. Workshop participants identified four process areas that could potentially be affected by the implementation of an enhanced coagulation or a softening process. Mitigation flowcharts are provided for each secondary effect to help utilities determine what if any course of action to pursue if enhanced coagulation or softening is implemented.