Effect of combinations of aquatic plants (Hydrilla, Ceratophyllum, Eichhornia, Lemna and Wolffia) on arsenic removal in field conditions

A field experiment was conducted in a combinatorial approach to evaluate the performance of five aquatic plants, singly and in all possible combinations of two plants, for As removal from 4 L of 2500 mu g L-1 As in 30 days. Under As stress, Hydrilla showed an increase in growth rate (19%) in comparison to control, while other plants demonstrated a decline. Among different combinations, Ceratophyllum + Lemna, Hydrilla + Ceratophyllum and Hydrilla + Wolffia showed higher growth in As (92%, 43%, and 33%, respectively) than under control conditions. Total As removal (mu g) in 30 days was found to be the maximum for Ceratophyllum Lemna (4365) followed by Hydrilla+ Ceratophyllum (3326) and Hydrilla + Wolffia (1896). In all combinations of plants, Hydrilla always contributed more than 50%. The study advocates the use of Hydrilla/Ceratophyllum as one plant of choice to be used in combination. It also proposes to screen for different combinations of two of more plants for better application of phytoremediation technology in field. (C) 2014 Elsevier B.V. All rights reserved.