Removal and inactivation of Cryptosporidium and microbial indicators by a quaternary ammonium chloride (QAC)-treated zeolite in pilot filters

A set of pilot filters packed with Zeolite filter media treated with a quaternary ammonium chloride (QAC) were evaluated to verify the proof of concept of their combined antimicrobial capabilities. Escherichia coli was removed and inactivated the most (2.83 log), followed by MS-2 (2.75 log), Klebsiella terriena (2.21 log), PRD-1 (1.95 log), Chlorella vulgaris (1.92 log), and Cryptosporidium parvum oocysts (1.78 log). Especially, inactivation of C parvum oocysts (1.19 log) was higher than physical removal (0.54 log). The data suggest that QAC-treated Zeolite in the pilot filters has microbial inactivation capabilities and may have useful applications in other types of filter media.