Steuer, AndreaAndreaSteuerKast, CharlotteCharlotteKastMahringer, DanielDanielMahringerFörster, ChristinaChristinaFörsterErnst, MathiasMathiasErnstRuhl, Aki SebastianAki SebastianRuhl2025-12-122025-12-122025-12-04Separation and Purification Technology 384: 136283 (2026)https://hdl.handle.net/11420/59630Viruses pose risks to human health and might be of special concern in filter backwash water recycling, yet there are no published studies on the subject. The fate of the bacteriophages MS2 and ΦX174 during biological filtration was studied at pilot scale. Furthermore, the efficacy of phage removal in ultrafiltration of filter backwash water was investigated for four different ultrafiltration (UF) membranes at laboratory scale. During biotic iron and manganese removal from groundwater (2.1–2.7 mg/L Fedis and 0.4–0.7 mg/L Mndis), both phages were removed by less than one log10 unit at filtration velocities of 7.5 m/h and 15.0 m/h. Treatment of filter backwash water (3.9–7.9 mg/L Fetotal) with a polyether sulfone flat-sheet UF membrane (pore size 26 nm) yielded a removal of MS2 phages of 4 log10 units and of ΦX174 of approx. 3 log10 units. Using different UF membranes revealed no clear relation between pore size and phage retention, with phage retention reaching up to 7 log10 units with pore sizes larger than phage diameters.en1383-58662025Elsevierhttps://creativecommons.org/licenses/by/4.0/Natural Sciences and Mathematics::579: Microorganisms, Fungi and AlgaeTechnology::628: Sanitary; Municipal::628.1: Water Supply SystemsJournal Articlehttps://doi.org/10.15480/882.1630310.1016/j.seppur.2025.13628310.15480/882.16303Journal Article