Effects of humic and fulvic acids on poliovirus concentration from water by microporous filtration

Abstract

Because naturally occurring organic matter is thought to interfere with virus adsorption to microporous filters, humic and fulvic acids isolated from a highly colored, soft suface water were used as model organics in studies on poliovirus adsorption to and recovery from electropositive Virosorb IMDS and electronegative Filterite fibers. Solutions of activated C-treated tap water containing 3, 10 and 30-mg/l concentrations of humic or fulvic acid were seeded with known amounts of poliovirus and processed with Virosorb 1MDS filters at pH 7.5 for Filterite filters at pH 3.5 (with and without 5 mM MgCl2). Organic acids caused appreciable reductions in virus adsorption and recovery efficiencies with both types of filter. Fulvic acid caused greater reductions in poliovirus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with poliovirus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced poliovirus recoveries by both types of filter, its greatest effect was on virus elution and recovery from Filterite filters. Single-particle analyses demonstrated MgCl2 enhancement of poliovirus association with both organic acids at pH 3.5. The mechanisms by which each organic acid reduced virus adsorption and recovery appeared to be different for each type of filter.