|SASIDHARAN, SALINI - University Of California|
|SIMUNEK, JIRI - University Of California|
|TORKZABAN, SAEED - Flinders University|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2018
Publication Date: 5/3/2018
Citation: Sasidharan, S., Bradford, S.A., Simunek, J., Torkzaban, S. 2018. Minimizing virus transport in porous media by optimizing solid phase inactivation. Journal of Environmental Quality. doi:10.2134/jeq2018.01.0027.
Interpretive Summary: One of the major risks associated with Managed Aquifer Recharge (MAR) operations are the presence of viruses in recovered drinking water. Saturated virus transport experiments were conducted under different temperatures (4 and/or 20°C), no-flow storage durations (0, 36, 46, and 70 days), and temperature cycling (flow at 20°C and storage at 4°C) conditions to investigate the ability to optimize virus death and thereby eliminate virus transport. The virus death increased with the storage period and temperature, and virus transport in aquifers could be eliminated within 2-3 months when the temperature was above 20°C. This finding will be of interest to scientists, engineers, government agencies, and health professional concerned with the microbial safety of MAR operations
Technical Abstract: The influence of virus type (PRD1 and FX174), temperature (flow at 4 and 20°C), a no-flow storage duration (0, 36, 46, and 70 d), and temperature cycling (flow at 20°C and storage at 4°C) on virus transport and fate were investigated in saturated sand-packed columns. The vast majority (84–99.5%) of viruses were irreversibly retained on the sand, even in the presence of deionized water and beef extract at pH = 11. The reversibly retained virus fraction (fr) was small (1.6 × 10^(-5) to 0.047) but poses a risk of long-term virus contamination. The value of fr and associated transport risk was lower at a higher temperature and for increases in the no-flow storage period due to the temperature dependency of the solid phase inactivation. A model that considered advective–dispersive transport, attachment (katt), detachment (kdet), solid phase inactivation (µs), and liquid phase inactivation (µl) coefficients, and a Langmuirian blocking function provided a good description of the early portion of the breakthrough curve. The removal parameters were found to be in the order of katt > µs >> µl. Furthermore, µs was an order of magnitude higher than µl for PRD1, whereas µs was two and three orders of magnitude higher than µl for FX174 at 4 and 20°C, respectively. Transport modeling with two retention, release, and inactivation sites demonstrated that a small fraction of viruses exhibited a much slower release and solid phase inactivation rate, presumably because variations in the sand and virus surface roughness caused differences in the strength of adhesion. These findings demonstrate the importance of solid phase inactivation, temperature, and storage periods in eliminating virus transport in porous media. This research has potential implications for managed aquifer recharge applications and guidelines to enhance the virus removal by controlling the temperature and aquifer residence time.