CONTINUOUS REMOVAL OF BOTH MUTAGENS AND MUTAGEN-FORMING POTENTIAL BY AN EXPERIMENTAL FULL-SCALE GRANULAR ACTIVATED CARBON TREATMENT SYSTEM

Trends in the removal of mutagens and of total organic carbon (TOC) were measured for granular activated carbon (GAC) in use at the Cincinnati Water Works. Sample points were settled river water, chlorinated sand filtered water, GAC-treated water, water from these two latter points stored 3 days in the presence of a free chlorine residual, and distributed water. No mutagens were detected from the settled water, so the great majority of mutagens entering GAC treatment were products of the chlorination step. These mutagens were preferentially removed by GAC treatment, and GAC effluent was greatly reduced in its potential to form mutagens upon rechlorination, even when the GAC was used several months beyond normal use for TOC removal. Analyses of residues extracted from the used GAC also indicated the efficient removal of waterborne mutagens.