AWWA JAW64052

This research investigated source waters from softening plants in Florida, Missouri, Nebraska, South Dakota, and Texas to evaluate how source water quality and varying lime doses affected softening, removal of natural organic matter (NOM), and disinfection byproduct (DBP) formation. Most lime softening plants are likely to be able to meet regulations for removal of organic carbon and limitations on DBP formation by operating with lime addition just below the level that causes dramatic reduction of the magnesium concentration. This operating condition is optimal because it limits the amount of sludge that could be created by enhanced softening. For managers of utilities that use precipitative softening, the findings provide insight into the effects of plant operation on the ability to remove NOM and control DBPs. In addition, the dose normalization developed for this research will allow utilities to easily compare their operations with those of other plants having different water characteristics. Includes 29 references, tables, figures.