UV INACTIVATION OF FLOC-ASSOCIATED MS-2 COLIPHAGE

The ability of ultraviolet (UV) light to disinfect MS-2 coliphage associated with alum floc was evaluated. Bench experiments were conducted in which MS-2, a viral surrogate, was either coagulated with kaolin clay particles or aggregated into viral clumps prior to UV exposure. The bench experiments were designed to represent particle sizes, viral aggregates, and turbidities encountered in drinking water treatment. A third condition, consisting of MS-2 in clear, phosphate buffer solution, served as a control for comparison. The results suggest that enmeshment within floc particles and aggregation into viral clumps protect viruses from UV disinfection. Up to a 1.1-log reduction in MS-2 inactivation was observed due to these factors. Viral enmeshment and aggregation were confirmed using transmission electron microscopy.