Removal of Emerging Waterborne Pathogens and Pathogen Indicators by Pilot‐Scale Conventional Treatment

Abstract

The goal of this project was to evaluate the removal of emerging pathogens and pathogen indicators by pilot‐scale coagulation, flocculation, sedimentation, and granular media filtration. The emerging pathogens included Cryptosporidium parvum oocysts, Encephalitozoon intestinalis spores, Escherichia coli O157:H7, and Aeromonas hydrophila. Bacteriophage MS2 and turbidity were used as pathogen indicators. This work revealed that some emerging pathogens were removed much more effectively than others. A. hydrophila was removed more effectively than C. parvum, and E. intestinalis spores and E. coli O157:H7 were the least effectively removed. For the water tested in this study, the results suggest that a change in filter effluent turbidity requirements from 0.5 to 0.3 ntu would not achieve a significant improvement in the reliability of pathogen removal. However, by setting filter effluent turbidity goals below 0.2 ntu, significant improvements in microbiological quality could be obtained. In general, the pilot‐plant data suggest that good removal of both turbidity and natural organic matter (NOM) decreases the risk of achieving poor emerging pathogen removal. In other words, optimizing the coagulation process for reduction of turbidity and NOM would improve removal of emerging pathogens.