Effect of Phragmites australis   and Typha latifolia   on biofiltration of heavy metals from secondary treated effluent

The present work deals with a promising approach for the removal of heavy metals from secondary treated wastewater using aquatic plants, which are economic and effective in separating metals from polluted water. Since the conventional sewage treatment processes were inefficient to remove heavy metals from wastewater, batch experiments of Phragmites australis, Typha latifolia and P. australis and T. latifolia grown in association and reference (unplanted) were carried out for 15 days of retention time for the removal of copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), iron (Fe), lead (Pb), and zinc (Zn) from the secondary treated effluent. Significantly, higher removal of the heavy metals in planted set than the reference revealed role of plants in their removal (analysis of variance, p < 0.05). Higher removal of Cr, Fe, and Zn (66.2 ± 3.5, 70.6 ± 1.2, and 71.6 ± 3.9 %) in the combination of the P. australis and T. latifolia than their individual culture suggested synergistic effect of both the plants in the removal of these metals. Positive relationship was observed between retention time and the removal of heavy metals. Mass balance equation has revealed that the loss of heavy metals in wastewater was equivalent to the net accumulation of heavy metals in plant and loss of heavy metals in natural degradation. P. australis showed higher accumulative capacities for Cu, Cd, Cr, Ni, Fe, and Pb than those of T. latifolia. The P. australis and T. latifolia grown in association might be utilized for the heavy metal removal in the tropical environment.

Keywords
Accumulation; Aquatic plants; Removal; Retention time; Synergistic effect