Cryptosporidium and microsphere removal during late in‐cycle filtration

Abstract

Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐media filter during optimized, end‐of‐run, and breakthrough operating conditions. Oocyst‐sized polystyrene microspheres were also evaluated as surrogates for C. parvum removal by filtration. At optimal conditions, the pilot‐scale filter consistently achieved ~5‐log removal of C. parvum and microspheres. During end‐of‐run operation when filter effluent turbidity levels were <0.1 ntu, median oocyst removals deteriorated to ~3 log. During early (0.1–0.3 ntu) and late (>0.3 ntu) breakthrough, filtration oocyst removals deteriorated to ~2.1 and ~1.4 log, respectively. Microsphere removals by filtration were similar to oocyst removals during both stable and challenged operating periods, suggesting that microspheres are useful surrogates for investigating C. parvum removal.