Norovirus Dynamics in Wastewater Discharges and in the Recipient Drinking Water Source: Long-Term Monitoring and Hydrodynamic Modeling

Abstract

Norovirus (NoV) that enters drinking water sources with wastewater discharges is a common cause of waterborne outbreaks. The impact of wastewater treatment plants (WWTPs) on the river Göta älv (Sweden) was studied using monitoring and hydrodynamic modeling. The concentrations of NoV genogroups (GG) I and II in samples collected at WWTPs and drinking water intakes (source water) during one year were quantified using duplex real-time reverse-transcription polymerase chain reaction. The mean (standard deviation) NoV GGI and GGII genome concentrations were 6.2 (1.4) and 6.8 (1.8) in incoming wastewater and 5.3 (1.4) and 5.9 (1.4) log genome equivalents (g.e.) L in treated wastewater, respectively. The reduction at the WWTPs varied between 0.4 and 1.1 log units. In source water, the concentration ranged from below the detection limit to 3.8 log g.e. L. NoV GGII was detected in both wastewater and source water more frequently during the cold than the warm period of the year. The spread of NoV in the river was simulated using a three-dimensional hydrodynamic model. The modeling results indicated that the NoV GGI and GGII genome concentrations in source water may occasionally be up to 2.8 and 1.9 log units higher, respectively, than the concentrations measured during the monitoring project.

Microbial risk assessment of drinking water based on hydrodynamic modelling of pathogen concentrations in source water

“…Furthermore, uncertainties are associated with the efficiency of virus enrichment procedure, the RNA extraction, cDNA synthesis and the qPCR. These uncertainties are outside of the scope of this article and are discussed elsewhere (Dienus et al, 2015).…”

“…The sewage volume used for analysis was 50 mL. The sewage was analysed for norovirus genogroups I and II (GGI and GGII) using quantitative real-time PCR (qPCR) based on reported methods (Dienus et al, 2015;Kageyama et al, 2003;Nordgren et al, 2009;Shieh et al, 1995) as described in Appendix A. The GGI and GGII were chosen, since they constitute the most important norovirus genogroups in terms of human infection (Matthews et al, 2012).…”

“…The obtained qPCR data (Table 1) (Dienus et al, 2015) were used to characterise the probability density functions for norovirus GGI and GGII in raw and treated sewage from the Holmängen WWTP. The virus concentrations were assumed to follow a gamma distribution with parameters ρ (shape) and λ (scale): Equation 1…”

Environmental and Adaptive Changes Necessitate a Paradigm Shift for Indicators of Fecal Contamination

“…In a more recent study, NoV was shown to remain detectable for over 3 years and infectious for at least 61 days in groundwater (139). Seasonal variation of NoV in source water and wastewater has been documented, with higher occurrence in colder periods (143)(144)(145), with the prevalence of NoV GII being greater than GI during colder periods (143,146). This reflects the GII infection incidence during this season (147).…”

Hydrodynamic modelling of the influence of stormwater and combined sewer overflows on receiving water quality: Benzo(a)pyrene and copper risks to recreational water

“…Liu et al 2015), and to quantify the relative impact of different sources (e.g. Dienus et al 2016). In addition, this approach can complement monitoring and to some extent address the limitations of analytical methods, such as cost, temporal resolution, and detection limits.…”