Removal of Pb and Zn in municipal wastewater by a consortium of four aquatic plants in vertical subsurface flow constructed wetland (VSF-CW)

Abstract

ABSTRACT The ability of a consortium of three emergent aquatic plants; Veronica anagallis-aquatica, Mentha longifolia, and Cyperus iria and one free-floating Nasturtium officinale was evaluated in outdoor vertical subsurface flow-constructed wetland (VSF-CW) experiments to remove lead and zinc elements in municipal wastewater. All species were able to withstand unsuitable conditions, as shown by the 100% survival rate. The percentage Pb and Zn removal rate under the synergetic condition of the consortium attained 92% and 97%, respectively. This was consistent with the highest removal capacity (14.3 and 17.1 mg/d/g) and highest metal uptake values (12.4 and 170.2 mg/plant) calculated for Pb and Zn, respectively. Free-floating N. officinale was considered suitable candidate for Zn phytoextraction (BAFs and TF >1). Emergent species have taken up high Zn in their roots, and are, therefore considered strong excluders of Zn, via phytostabilization (BAFs > 1 and TF <1). All species eliminated Pb from wastewater by rhizofiltration (BAFs and TF <1).