REMOVING CRYPTOSPORIDIUM BY DISSOLVED-AIR FLOTATION

Bench-scale studies were used to investigate the effectiveness of diss olved-air flotation (DAF) for the removal of Cryptosporidium parvum oo cysts from a drinking water supply. Oocysts were spiked into a natural water at a concentration of 3-4 x 10(5) oocysts/L. Results indicate t hat DAF achieved a > 2-log removal of oocysts under a variety of condi tions. In addition, flotation was a superior clarification process to sedimentation for the conditions tested. Coagulation and DAF condition s that minimize residual turbidity and maximize the removals of organi c matter are conditions that produce high log removals of Cryptosporid ium.