Enhanced removal of norovirus surrogates, murine norovirus and tulane virus, from aqueous systems by zero-valent iron

Abstract

Viral contamination can compromise the safety of water utilized for direct consumption, produce irrigation, and postharvest washing of produce. Zero-valent iron (ZVI) is used commercially for chemical remediation of water and has been demonstrated to remove some biological contaminants from water in laboratory and field studies. This study investigated the efficacy of ZVI to remove human norovirus surrogates, Tulane virus (TV) and murine norovirus (MNV), from water and to characterize the reversibility and nature of viral association with ZVI. Genomic material of TV and MNV recovered from the effluent of inoculated water treatment columns containing a 1:1 mixture of ZVI and sand was 2 and 3 log, respectively, less than that recovered from the effluent of treatment columns containing only sand. Elution buffers (citrate buffers, pH 4 and 7, and virus elution buffer, pH 9.5, with and without added 1 M NaCl) did not increase recovery of infectious TV and MNV from ZVI as compared with elution with water alone. TV-inoculated lettuce washed with water in the presence of ZVI yielded 1.5 to 2 log fewer infectious TV from washwater as compared with lettuce washed with water alone or in the presence of sand. These data demonstrate the enhanced removal of human norovirus surrogates, TV and MNV, from water by ZVI and provide indications that unrecovered viruses are not readily disassociated from ZVI by buffers of various pH and ionic strength. These findings warrant further investigation into larger-scale simulations of water remediation of viral contaminants for potential application in the treatment of water used for drinking, irrigation, and food processing.