The influence of nitrilotriacetic acid (NTA) on metal mobilization from a contaminated river sediment

Abstract

Sediment samples and river water used in this study were collected from a contaminated river, namely, the Lau-Che river located in northern Taiwan, in order to investigate the mobilization of heavy metals from river sediment influenced by NTA in a simulated continuous-flow channel reactor. Concurrently, the kinetic model was applied to describe the mobilization of heavy metals from sediments. When the NTA was first discharged into the reactor, the initial adsorption of NTA by the sediment decreased the mobilization of heavy metals and changed the released behavior of heavy metals. It made bad agreement between models and experimental data. Due to the bacteria were completely acclimated to degrade NTA in the former experiment, the release of heavy metals was significant at the initial addition of NTA and the concentrations of heavy metals in the liquid phase decreased after that the NTA was degraded by bacteria. The maximum mobilization of heavy metals increased with the increase of concentration of NTA. According to the experimental data, the mobilization of heavy metals by NTA appeared to follow multiple first-order reaction model, two constant model, or diffusion model. (C) 1998 IAWQ. Published by Elsevier Science Ltd.