Viral Fate and Transport Modeling under Salinity Impactby Frank T. C. Tsai, (M.ASCE),
Kelly R. Rusch, (M.ASCE),
Document Type: Proceeding Paper
Part of: World Environmental and Water Resources Congress 2008: Ahupua'A
This research studied the impact of salinity on sorption and transport of MS-2 in saturated sand through one-dimensional column experiments. MS-2 was used as a surrogate to understand viral fate and transport in subsurface environment. The controlled conditions in all experiments included constant flow rates (4.0 cm/min), neutral condition (pH=7.0 ± 0.5), and constant temperature (25 ± 0.20C). Bromide was adopted as the conservative tracer to evaluate the dispersion coefficient of MS-2 in the column. The MS-2 in nanopure water showed weak adsorption effect due to its same negative charge as the sand. The MS-2 in saline water showed dramatically enhanced adsorption effect. This result can be explained by two-site sorption process. Salinity could increase MS-2 attachment by compressing double layers on reversible sorption site, increasing charge intensity on irreversible sorption site, and reversing charges on the surface of silica powder. A fate and transport model, coupled with two-site sorption process, was developed to describe MS-2 sorption and transport in 1-D sand column under different salinity conditions. The fate and transport equations were solved numerically using the Crank-Nicholson method. Model sorption parameters were identified using BFGS method and sensitivity equation method based on measured MS-2 breakthrough data. The proposed model showed good agreement with the experimental data under different salinity conditions. Identified sorption parameters showed that salinity could increase MS-2 retention on both reversible and irreversible sorption site by increasing attachment rate and retention capacity on irreversible site, increasing attachment rate while decreasing detachment rate on reversible site.
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