Heavy meatals removal by a promising locally available aquatic plant, Najas graminea Del., in Taiwan

This study uses an aquatic plant, Najas graminea Del., to treat man-made wastewater containing single and/or binary components of copper, lead, cadmium and nickel. Adsorption experiments demonstrate that the adsorption process correspond to the Lagergren kinetic model with the rare constant close to 0.01 min(-1); meanwhile, the equilibrium results corresponds to the Langmuir adsorption isotherm. Notably, the rate constants of metals are not significantly different between each other. Competitive effect on the adsorption kinetics of cadmium is insignificant with the background solute (lead) concentration up to 10 mg/l; while significant deviation observed with concentration of lead reached 100 mg/l. In addition the maximum adsorption density of cadmium is reduced by around 50% in the presence of 100 mg/l of lead. A simulated copper plating wastewater is also treated by Najas graminea Del, to demonstrate its efficiency in removing metals from wastewater with multi-cations/anions. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.