Rhizofiltration potential of Arundo donax for cadmium and zinc removal from contaminated wastewater

The main aim of the presented work was to design and characterize the rhizofiltration system comprised of giant reed plants ( Arundo donax L.), as species with phytoremediation potential, for the removal of cadmium as a toxic metal and zinc as an important microelement from model solutions spiked with radionuclides 109 Cd and 65 Zn. The possibility of effective cadmium and zinc rhizofiltration by the root system of giant reed plants under continuous flow conditions to achieve complete decontamination was confirmed. The highest 109 Cd and 65 Zn specific radioactivity (Bq g −1 ; dry mass) was found in case of plants located near the input of the solution into the system, whereby the radioactivity in the plants decreased in the direction of the solution flow within the system. On the other hand, gradual increasing of the concentration ratio [Cd] shoot : [Cd] root within this horizontal plants location was observed. Individual experiments showed that the efficiency of cadmium rhizofiltration decreased in the order of model solutions: synthetic wastewater ( χ = 505 μS cm −1 ), deionized water ( χ = 29.6 μS cm −1 ), 100 % Hoagland medium ( χ = 1675 μS cm −1 ). The same results were also found in case of zinc rhizofiltration. For the description of cadmium and zinc rhizofiltration processes, the kinetic mathematical models widely applied for sorption processes under continuous flow conditions were successfully used.