Chromium and Zinc removal from synthetic industrial wastewater in pilot-scale constructed wetlands planted with Cyperus odoratus L.

Introduction: Constructed wetlands (CWs) are a recognized technology to treat industrial wastewater. Objective: A pilot system of two horizontal subsurface flow CWs was used to remove Cr and Zn from industrial synthetic wastewater. Method: The study was carried out at Universidad del Atlántico in Barranquilla, Colombia. Two containers of 0.375 m2 were filled with a gravel bed (~10 mm and 40% of porosity), and a 0.3 m water column. One container was planted with Cyperus odoratus L. and another without plants was used as a control. Results:  The removal efficiency of Cr and Zn was 93% and 96% in the CW planted, respectively, and 67% and 98% removal were obtained in the unplanted system with statistical differences (P<0,05). The observed difference in biomass production (0.1 and 0.6 kg/m2) could be related to seasonal weather that could have favored the growth of the plant. C. odoratus reached a Translocation Factor greater than 1.5 for Cr and Zn, which is greater than that, reported by others for Cyperus species. However, a Bioconcentration Factor > 13.6 for Zn and < 7.7 for Cr indicated that C. odoratus is an accumulator species for Cr and Zn. Sorption metal processes in gravel can be occurring due to the high removal efficiency of Zn in unplanted systems Conclusions:  These results show that C. odoratus could be recommended for use in constructed wetlands technology due to fast-growing and absorption and translocation heavy metals capacity.