Fate and Transport of Viruses within a High-Rate Plug-Flow Biofilter Designed for Non-Membrane-Based Indirect Potable Reuse Applications

Numerous chronic health effects might be caused by the presence of chemical constituents in reclaimed water; however, an acute risk for water-borne diseases is mostly associated with pathogens. For potable reuse applications, the greatest risk among pathogens is posed by viruses due to their small size and low infectious dose. An advanced water treatment train not utilizing high-pressure membranes but employing the novel SMARTplus biofilter with highly controlled plug-flow and redox conditions was proposed and tested during a 3D-pilot-scale study as a barrier against viruses. Spiking tests with bacteriophages (MS2 and ϕX174) and murine norovirus-1, accompanied by the conservative tracer, primidone, were conducted to study their transport and maximal reduction under controlled hydraulic conditions. While maintaining plug-flow conditions, mean log reduction values (LRVs) of 5.1, 5.0, and 3.5 were achieved for MS2, ϕX174, and murine norovirus-1, respectively. Given the short hydraulic retention time (HRT) of 12.6 h and a travel distance of 6 m, the demonstrated LRVs in the pilot-scale SMARTplus bioreactor were significantly higher than conventional slow sand filters. This SMARTplus-based advanced water treatment train, employing post UV-disinfection followed by subsequent groundwater recharge as environmental buffer, would comply with the performance targets for potable water reuse defined by WHO.