Demonstrating the reduction of enteric viruses by drinking water treatment during snowmelt episodes in urban areas

Abstract

This study investigates short-term fluctuations in virus concentrations in source water and their removal by full-scale drinking water treatment processes under different source water conditions. Transient peaks in raw water faecal contamination were identified using in situ online β- d -glucuronidase activity monitoring at two urban drinking water treatment plants. During these peaks, sequential grab samples were collected at the source and throughout the treatment train to evaluate concentrations of rotavirus, adenovirus, norovirus, enterovirus, JC virus, reovirus, astrovirus and sapovirus by reverse transcription and real-time quantitative PCR. Virus infectivity was assessed through viral culture by measurement of cytopathic effect and integrated cell culture qPCR. Virus concentrations increased by approximately 0.5-log during two snowmelt/rainfall episodes and approximately 1.0-log following a planned wastewater discharge upstream of the drinking water intake and during a β- d -glucuronidase activity peak in dry weather conditions. Increases in the removal of adenovirus and rotavirus by coagulation/flocculation processes were observed during peak virus concentrations in source water, suggesting that these processes do not operate under steady-state conditions but dynamic conditions in response to source water conditions. Rotavirus and enterovirus detected in raw and treated water samples were predominantly negative in viral culture. At one site, infectious adenoviruses were detected in raw water and water treated by a combination of ballasted clarification, ozonation, GAC filtration, and UV disinfection operated at a dose of 40 mJ cm −2 . The proposed sampling strategy can inform the understanding of the dynamics associated with virus concentrations at drinking water treatment plants susceptible to de facto wastewater reuse.

SARS-CoV-2 in a stream running through an underprivileged, underserved, urban settlement in São Paulo, Brazil: A 7-month follow-up

“…We believe that this should not be taken into account, as we used extremely contaminated water. Cytopathic effect can be caused by a variety of enteric viruses ( Sylvestre et al, 2021 ) and is not necessarily evidence of viable SARS-CoV-2.…”

Coliphages as viral indicators of sanitary significance for drinking water

“…There are other online monitors such as turbidity and particle-size distribution which are being used in a diagnostic capacity by drinking water treatment plants (DWTPs) operators for monitoring raw and treated water quality. Interesting applications showed that elevated water flow levels linked to rainfall or snowmelt events increased the viral and phage concentrations in a catchment (Fauvel et al, 2016 ; Sylvestre et al, 2021 ). Infectious F-specific RNA bacteriophage concentrations increased during rainfall events (Fauvel et al, 2016 ), whereas viral concentrations increased by ~0.5-log during two snowmelt/rainfall episodes and ~1.0-log following a planned wastewater discharge upstream of the drinking water intake (Sylvestre et al, 2021 ).…”

“…Interesting applications showed that elevated water flow levels linked to rainfall or snowmelt events increased the viral and phage concentrations in a catchment (Fauvel et al, 2016 ; Sylvestre et al, 2021 ). Infectious F-specific RNA bacteriophage concentrations increased during rainfall events (Fauvel et al, 2016 ), whereas viral concentrations increased by ~0.5-log during two snowmelt/rainfall episodes and ~1.0-log following a planned wastewater discharge upstream of the drinking water intake (Sylvestre et al, 2021 ). Another approach is to utilize enzyme-based sensors specific to coliforms.…”

“…These provide rapid sensitive online monitoring, providing a proxy for culture-based assays. Online enzyme sensors such as β-D-glucuronidase provided estimates of increased viral loads, for example, transient peaks in raw water fecal contamination were identified at two urban DWTPs (Sylvestre et al, 2021 ). However, the enzyme sensors monitor bacterial indicators, and although their application for viral or phage quantification may not be accurate, the automated enzymatic sensors could be practically used to trigger intensive sampling campaigns.…”

Temporal variations of human and animal Rotavirus A genotypes in surface water used for drinking water production

“…Environmental water is often contaminated with wastewater from cities or farms and may contain both human and animal pathogens. Rotaviruses are viral agents that cause severe diarrheal disease and death in infants, children, and young animals ( Dhama et al, 2009 ) and have been detected in both surface and groundwater sources ( Miura et al, 2019 , 2021 ; Sylvestre et al, 2021 ). Rotaviruses have been identified as potential reference pathogens in the WHO Guidelines for Drinking-Water Quality ( WHO, 2017 ).…”