AWWA JAW17238

The primary purpose of the pilot study described in this article was to evaluate the efficiency of sedimentation and of coarse anthracite media for removing Giardia cysts. Removal of cysts by sedimentation was observed to range from sixty-five to ninety-three percent and was generally similar to removal of turbidity. The coarse anthracite media produced water of inferior quality when alum was the only coagulant, but its performance was found to be improved by the use of a highmolecular-weight, slightly anionic polymer. Cyst concentrations appeared to be higher than usual during the initial phase of a filter run, indicating that a filter-to-waste period may be desirable. The authors conclude that effective control of Giardia cysts depends on the multiple-barrier concept. Includes 11 references, tables, figures.