Viral pathogens in urban stormwater runoff: Occurrence and removal via vegetated biochar-amended biofilters

Urban runoff is one of the greatest sources of microbial pollution to surface waters. Biofilters can limit the impact of stormwater runoff on surface water quality by diverting runoff from receiving waters. However, our understanding of how biofilter design choices, including the addition of vegetation and geomedia, may impact the removal of pathogens is lacking. In this study, we characterized viruses (adenovirus, enterovirus, norovirus GII, crAssphage) in San Francisco Bay area urban runoff and assessed the removal of lab-cultured viruses (MS2, adenovirus 2, coxsackievirus B5) from biochar-amended biofilter mesocosms during challenge testing. We quantified viruses using (RT-)qPCR and F+ coliphage plaque assays. We found that all the pathogenic viruses targeted were found at low concentrations (adenovirus: all positive samples were