Rapid bacteriophage MS2 transport in an oxic sandy aquifer in cold climate: Field experiments and modeling

Abstract

Virus removal during rapid transport in an unconfined, low-temperature (68C) sand and gravel aquifer was investigated at a riverbank field site, 25 km south of Trondheim in central Norway. The data from bacteriophage MS2 inactivation and transport experiments were applied in a two-site kinetic transport model using HYDRUS-1D, to evaluate the mechanisms of virus removal and whether these mechanisms were sufficient to protect the groundwater supplies. The results demonstrated that inactivation was negligible to the overall removal and that irreversible MS2 attachment to aquifer grains, coated with iron precipitates, played a dominant role in the removal of MS2; 4.1 log units of MS2 were removed by attachment during 38 m travel distance and less than 2 days residence time. Although the total removal was high, pathways capable of allowing virus migration at rapid velocities were present in the aquifer. The risk of rapid transport of viable viruses should be recognized, particularly for water supplies without permanent disinfection.

Uncertainty Analysis and Identification of Key Parameters Controlling Bacteria Transport Within a Riverbank Filtration Scenario

“…It is often negligible at laboratory scales, where residence times are typically shorter than a day (e.g., Sasidharan et al., 2017). However, the significance of inactivation increases when considering residence times associated with field scale scenarios (Kvitsand et al., 2015). Yet, the main characteristics of inactivation depend on the individual species considered, and on physical and biogeochemical conditions.…”

“…These authors conclude that other parameters, such as temperature and oxygen concentration, influence inactivation through control of the general microbiological activity. Inactivation is typically modeled as a first‐order kinetics (e.g., Hornstra et al., 2018; Kvitsand et al., 2015). However, a two‐rate or a bi‐phasic model might be necessary for settings where inactivation is documented to decrease with time.…”

“…Blaschke et al (2016) and Derx et al (2013) model bio-colloid transport under various conditions (varying, e.g., flow velocity, porosity, and vadose zone properties) without considering the impact of hydraulic conditions on bio-colloid removal coefficients. Kvitsand et al (2015) and Hornstra et al (2018) consider models with increased complexity upon relying on kinetic attachment/detachment formulations. The study of Kvitsand et al (2015) relies on a two-site attachment model, which is explained by the presence of chemical heterogeneity, to fit observed MS2 breakthrough curves.…”

“…Kvitsand et al (2015) and Hornstra et al (2018) consider models with increased complexity upon relying on kinetic attachment/detachment formulations. The study of Kvitsand et al (2015) relies on a two-site attachment model, which is explained by the presence of chemical heterogeneity, to fit observed MS2 breakthrough curves. Field scale models often cannot encompass the full process complexity of laboratory scale models or include all uncertain model parameters in the model calibration due to the high computational costs.…”

The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models

“…Virus inactivation is generally assumed to follow a first-order process where the inactivation rate of viruses is thought to be constant over time . This assumption has been successfully applied to several studies modeling both virus inactivation in batch inactivation experiments (Bae and Schwab 2008;Yates et al 1985) and more comprehensive studies of virus removal in flowing soil-water systems Kvitsand et al 2015;Schijven et al 2016). However, Hurst et al (1992) argue that virus inactivation is a time-dependent process and is not adequately represented by a constant inactivation rate.…”