Objectives: The present study investigates the applicability of water hyacinth (Eichhornia crassipes), a tropical aquatic plant with reported heavy metal hyper-accumulation in microcosm floating wetland treatment systems designed to remediate AMD with copper (Cu) and cadmium (Cd) concentrations exceeding threshold limits.

Methods: Twelve water hyacinth samples were prepared with varying concentrations of Cu (1 mg/L, 2 mg/L, 4 mg/L) and Cd (0.005 mg/L, 0.01 mg/L, 0.02 mg/L). Water samples of 5 ml each were collected from each sample at 24-hour intervals for analysis with an atomic absorption spectrometer.

Results: Plant growth varied according to Cu and Cd concentrations and no plants survived for more than 14 days. There was a significant discrepancy in the rate at which the Cd concentrations abated. The rate of reduction was rapid for higher concentrations and after 24 hours a substantial reduction was achieved. There was a reduction in Cu concentration after the first 24-hour period, and after the next 24-hour period the concentrations were again elevated in the samples at initial concentrations of 2 mg/L and A4 mg/L. 4 mg/L Cu concentration was shown to be toxic to the plants, as they had low accumulations and rapid dying was evident.

Conclusions: Water hyacinth has the capability to reduce both Cu and Cd concentrations, except at an initial concentration of 4 mg/L of Cu, which was toxic to the plants.