Phytoremediation of chromium and manganese by Ipomoea aquatica Forssk. from aqueous medium containing chromium-manganese mixtures in microcosms and mesocosms

摘要

Ipomoea aquatica-an aquatic macrophyte-could remove chromium and manganese from their mixtures after 96 h exposure at a maximum rate of 82.8% and 93.9%, respectively, in microcosms. The removal rates were higher (90.4% and 94.5%, respectively) after 96 h exposure in mesocosms with gravel beds and vertical subsurface flow. The higher removal rates in mesocosm were probably due to a wide range of partitioned micro-environments close to the root boundaries, and within the biofilms on both root and gravel surfaces. The Cr and Mn removal efficiencies of I. aquatica increased with increasing Cr or Mn concentrations in the medium. The study reveals the potential of I. aquatica-a fast-growing species that can proliferate by fragmentation-to effectively remove Cr and Mn within a relatively short period of time, thereby raising the prospect of its use in phytoremediation of wastewater contaminated with these metals.