Assessment of human virus removal during municipal wastewater treatment in Edmonton, Canada

Aims: To assess the removal of viruses through the multiple steps of wastewater treatment in a full-scale municipal wastewater treatment plant in Alberta, Canada. Methods and Results: Samples were collected after each of the five treatment steps for a period of 16 months. The amount of viruses and their infectivity were analysed using real-time quantitative PCR (qPCR) and integrated viral cell culture (ICC), respectively. Bacterial indicator Escherichia coli was also tested using membrane filtration. Seven viruses including Norovirus (NoV), Rotavirus (RV), Sapovirus (SaV), Astrovirus (AsV), Adenovirus (AdV), Enterovirus (EV) and JC virus (JCV) were detected in 16 primary effluents in which infectious viruses were present. Different treatment steps showed various efficiencies in virus removal, with membrane ultrafiltration as the most effective at 4.6-7.0 log reduction. Conclusions: We observed high prevalence of viruses in raw wastewater and different viral reduction after various treatment steps. The discharge of treated wastewater with infectious viruses represents potential risks to human, animal and environmental health. Significance and Impact of the Study: This study provides a comprehensive assessment of the removal of NoV, RV, SaV, AsV, AdV, EV, JCV and Reovirus from wastewater by current procedures of municipal wastewater treatment and discusses the applicability of various viruses as viral indicators for water quality.