Reductions of human enteric viruses in 10 commonly used activated carbon, polypropylene and polyester household drinking-water filters

Liping Pang; Susan Lin; Erin McGill; Annabelle Tham; Joanne Hewitt; Chris Nokes; Vernon Ward

doi:10.1016/j.watres.2022.118174

Reductions of human enteric viruses in 10 commonly used activated carbon, polypropylene and polyester household drinking-water filters

Water Res. 2022 Apr 15:213:118174. doi: 10.1016/j.watres.2022.118174. Epub 2022 Feb 11.

Authors

Liping Pang¹, Susan Lin², Erin McGill², Annabelle Tham³, Joanne Hewitt⁴, Chris Nokes², Vernon Ward⁵

Affiliations

¹ Institute of Environmental Science and Research Ltd, PO Box 29181, Christchurch 8540, New Zealand. Electronic address: liping.pang@esr.cri.nz.
² Institute of Environmental Science and Research Ltd, PO Box 29181, Christchurch 8540, New Zealand.
³ Institute of Environmental Science and Research Ltd, PO Box 29181, Christchurch 8540, New Zealand; Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
⁴ Institute of Environmental Science & Research Ltd, Kenepuru Science Centre, PO Box 50348, Porirua 5240, New Zealand.
⁵ Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.

PMID: 35183016
DOI: 10.1016/j.watres.2022.118174

Abstract

Drinking-water treatment in non-networked rural communities relies on the use of point-of-use (PoU) household filters. Source waters treated by PoU filters are often microbially contaminated, but information about human enteric virus reductions in these filters is limited. This study evaluated human rotavirus, adenovirus and norovirus reductions in 10 commonly used, new PoU carbon, polypropylene and polyester microfilters. The viruses were spiked into chlorine-free tap water (pH 8.0, ionic strength 1.22 mM), and 3 sequential challenge tests were conducted in each filter under a constant flow rate of 1 L/min. In most of the filters investigated, the norovirus and adenovirus reductions were similar (P > 0.49). Compared with the norovirus and adenovirus reductions, the rotavirus reductions were significantly lower in the carbon filters (P ≤ 0.009), which may relate to rotavirus's higher zeta potential and lower hydrophobicity. Virus reductions appeared to be dictated by the filter media type through electrostatic and hydrophobic interactions; the effects of filter media pore sizes on virus reductions via physical size-exclusion were very limited. The virus reductions in the carbon filters were significantly greater than those in the polypropylene and polyester filters (P ≤ 0.0001), and they did not differ significantly between the polypropylene and polyester filters (P > 0.24). None of the filters met the "protective" rotavirus reduction level (≥3 log₁₀) required for household drinking-water treatment. Our study's findings highlight a critical need for additional water treatment when using PoU microfilters, for example, water boiling or ultraviolet radiation, or the use of effective surface-modified filter media to prevent drinking-waterborne infections from enteric viruses.

Keywords: Attachment; Drinking water; Enteric viruses; Log(10) reduction value; Point-of-use filters.