Removal of viruses and bacteriophages from drinking water using zero-valent iron

Abstract

Zero-valent iron (ZVI) has been shown to remove and inactivate bacteriophages in synthetic groundwater, which suggests that it may be potentially useful for drinking water treatment. As an effort to assess this possibility, we assessed the effectiveness of ZVI to remove pathogenic viruses from two water treatment plant samples (from Allentown, PA and Newark, DE) through a series of column experiments. Removal of Aichi virus (AiV), Adenovirus 41 (Ad41), and the bacteriophages MS2 and ϕX174 in columns packed with clean sand only and sand with a layer of ZVI-sand mix (1:1, v/v) was examined through pulse tests under saturated flow conditions. With the exception of Ad41, removal of all viruses by sand was zero or limited in all cases, regardless of the water used. In contrast, ZVI-containing columns gave removal efficiencies between 4.5 and 6 logs for all viruses and all waters studied. Ad41 was retained markedly by sand and even more strongly (by 2–3 logs) by ZVI and did not breakthrough fully from either column even after 32 pore volumes. The significant retardation of Ad41 is ascribed to the relatively high isoelectric points of the long and short fibers of Ad41. Our results, combined with studies elsewhere that demonstrate organic matter removal by ZVI and iron oxides, suggest ZVI may potentially offer a simple and low-cost option to help utilities control microorganisms, disinfection byproducts, and chlorine residuals simultaneously. Possible applications of ZVI in water treatment plants are proposed and the potential benefits are discussed.