Nutrient and Removal Kinetics Impacts on Salt Phytoremediation by Atriplex patula and Typha angustifolia

Deicing salts are spread on roads in northern countries to ensure driver safety during snowfalls. These salts dissolve in road runoff. Various treatment devices have been developed to treat road runoff, but none can remove deicing salt. Phytoabsorption in a constructed wetland is suggested as an innovative option. Two species ( Atriplex patula and Typha angustifolia) were selected from previous experiments to be established as the wetland vegetation. However, as this treatment is innovative, some challenges arose during the design process in determining an optimal residence time and substrate nutrient supply to maximize salt removal by plant absorption in a constructed wetland. To overcome those difficulties, this study evaluated the impact of nutrient concentration on plant salt absorption and the removal kinetics of plant salt absorption. Plants were grown in hydroponic conditions in two nutrient solutions with different nutrient concentrations ( high and low)-Hoagland 1/4 and a synthetic road runoff solution-to assess their influence on salt absorption. Plants grown with the Hoagland 1/4 solution showed the highest aboveground biomass and the highest salt uptake ( up to 13 gNa(+)/m(2) and 50 gCl(-)/m(2)). To determine the salt absorption kinetics, plants were exposed for a period of one week to a solution of 1,500 mg NaCl/L. Pseudo-first- and pseudo-second order models showed good agreement with experimental data. Salt concentrations in plant tissues increased and reached their maximum after one week. These results determined optimal nutrient supply ( Hoagland 1/4) and residence time ( one week) with the aim of improving the performance of salted road runoff treatments by phytoabsorption. (C) 2014 American Society of Civil Engineers.