Potential of Phragmites australis in Vertical Flow Constructed Wetland for Heavy metals removal from Urban wastewater

Abstract

Abstract The present study demonstrates the feasibility of a constructed wetland (CW) planted with Phragmites australis to treat the heavy metals (HMs) from wastewater. Wastewater samples were collected from the in-let, out-let of the CW and analyzed for HMs such as Cadmium (Cd), Zinc (Zn), Lead (Pb), and Copper (Cu) using standard methods. Similarly, samples of Phragmites australis and sediments were also analyzed for selected HMs. Results indicate that the removal efficiencies of the planted CWs for Cd, Zn, Cu and Pb were 89.34, 76.27, 68.14, and 66.42%, respectively. On the other hand, the removal efficiency of the unplanted system was significantly lower, ranging between 18.27 and 33.16%. The plant played a strategic role in the absorption and accumulation of pollutants, the greatest mean concentrations of HMs were found in the below-ground plant parts of P. australis. While, the survey revealed that the amount of HMs accumulated in the aerial horizon represents often an only small adsorbed fraction, but higher than the concentrations measured at the underground horizon of the soil. The biological accumulation factor confirms the previous observations, that the roots and the rhizomes are the most bio-accumulator of all analyzed elements and, the results of the transfer factor values were estimating the ability of P. australis to transfer HMs from roots to sheets, which varied between 0.97 and 1.61 by the following order: Cd > Pb > Zn > Cu.