Transport and fate of viruses in sediment and stormwater from a Managed Aquifer Recharge site

Abstract

a b s t r a c tEnteric viruses are one of the major concerns in water reclamation and reuse at Managed Aquifer Recharge (MAR) sites. In this study, the transport and fate of bacteriophages MS2, PRD1, and UX174 were studied in sediment and stormwater (SW) collected from a MAR site in Parafield, Australia. Column experiments were conducted using SW, stormwater in equilibrium with the aquifer sediment (EQ-SW), and two pore-water velocities (1 and 5 m day À1 ) to encompass expected behavior at the MAR site. The aquifer sediment removed >92.3% of these viruses under all of the considered MAR conditions. However, much greater virus removal (4.6 logs) occurred at the lower pore-water velocity and in EQ-SW that had a higher ionic strength and Ca 2+ concentration. Virus removal was greatest for MS2, followed by PRD1, and then UX174 for a given physicochemical condition. The vast majority of the attached viruses were irreversibly attached or inactivated on the solid phase, and injection of Milli-Q water or beef extract at pH = 10 only mobilized a small fraction of attached viruses (<0.64%). Virus breakthrough curves (BTCs) were successfully simulated using an advective-dispersive model that accounted for rates of attachment (k att ), detachment (k det ), irreversible attachment or solid phase inactivation (l s ), and blocking. Existing MAR guidelines only consider the removal of viruses via liquid phase inactivation (l l ). However, our results indicated that k att > l s > k det > l l , and k att was several orders of magnitude greater than l l . Therefore, current microbial risk assessment methods in the MAR guideline may be overly conservative in some instances. Interestingly, virus BTCs exhibited blocking behavior and the calculated solid surface area that contributed to the attachment was very small. Additional research is therefore warranted to study the potential influence of blocking on virus transport and potential implications for MAR guidelines.

Minimizing Virus Transport in Porous Media by Optimizing Solid Phase Inactivation

“…Sasidharan et al (2017b) previously attributed this temperature dependency to slight increases in the adhesive interaction on heterogeneous surfaces and slight differences in mass transfer (η in Table 1). Similar to Sasidharan et al (2017a), it was found that k att1 > μ s1 >> μ l . Significantly, μ s1 was two and one orders of magnitude higher than μ l for PRD1, whereas μ s1 was two and three orders of magnitude higher than μ l for ΦX174 at 4 and 20°C, respectively.…”

“…Phase III consisted of eluting the column with virus‐free 10 mM NaCl solution at a pore‐water velocity of 0.1 m d −1 . Columns were eluted with Milli‐Q water and beef extract with pH 11 (Sasidharan et al, 2017a) during Phases IV and V, respectively, at a pore‐water velocity of 5 m d −1 . The column effluent samples were collected using a Spectra/Chrom CF‐1 Fraction Collector (Spectrum), and the concentration of viruses was quantified using the DLA method (Sasidharan et al, 2016).…”

“…A growing body of research is continuously evaluating and validating processes involved in pathogen attenuation in aquifers. Most studies have used laboratory‐scale columns packed with clean sand (Sasidharan et al, 2017b; Schijven et al, 2002) or sediment collected from potential MAR sites (Hijnen et al, 2005; Sasidharan et al, 2017a), whereas only a few field‐scale studies have been conducted (Page et al, 2015; Pieper et al, 1997; Sidhu et al, 2010). Viruses are generally considered to be the microbial pathogen of greatest risk because of their low infectious dose and potential to travel long distances in the subsurface (Reynolds et al, 2008).…”

“…Viruses are generally considered to be the microbial pathogen of greatest risk because of their low infectious dose and potential to travel long distances in the subsurface (Reynolds et al, 2008). Mechanisms that will lead to virus removal during MAR include inactivation in the liquid phase, attachment on the solid surface, and subsequent inactivation on the solid surface (Harvey and Ryan, 2004; Sasidharan et al, 2017a; Schijven and Hassanizadeh, 2000). However, current MAR guidelines only consider liquid phase inactivation as a reliable mechanism to remove viruses (Hannappel et al, 2014; Johnson, 1989; NRMMC–EPHC–NHMRC, 2009).…”

Managed Aquifer Recharge (MAR) in Sustainable Urban Water Management

“…Contamination of aquifers by virus and protozoan pathogens present a higher public health risk than bacteria due to low infectious dose and high environmental stability [48][49][50][51][52]. While viruses and protozoa are obligate intracellular parasites that require a host for metabolism, growth, and replication however, they can persist in infectious state in the groundwater under certain conditions (e.g., anoxic conditions and lower temperatures [49]).…”