Removal of bacteriophages MS2 and ΦX174 in biotic iron and manganese filters and in ultrafiltration of iron and manganese containing backwash water

Viruses 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 Fe dis and 0.4–0.7 mg/L Mn dis ), both phages were removed by less than one log 10 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 Fe total ) with a polyether sulfone flat-sheet UF membrane (pore size 26 nm) yielded a removal of MS2 phages of 4 log 10 units and of ΦX174 of approx. 3 log 10 units. Using different UF membranes revealed no clear relation between pore size and phage retention, with phage retention reaching up to 7 log 10 units with pore sizes larger than phage diameters. • First study on phage removal from filter backwash water. • Comparison of one ceramic and two polymeric UF membranes in dead-end. • Comparison of pore size, membrane material, and water matrix on phage removal. • Phage removal from filter backwash was high for all studied membranes. • Interactions between phages and membrane surfaces influence phage removal.