Comparison of removal efficiencies in Mediterranean pilot constructed wetlands vegetated with different plant species

Constructed wetlands (CWs) are wastewater treatment systems suitable for reducing a contaminant load in wastewater, economically. In this study, vegetated and unplanted pilot gravel filters, for tertiary treatment of effluent from a conventional wastewater treatment plant (trickling filter) in Southern Italy (Sicily), are compared with pollutant removal efficiencies. Two beds are unplanted (control systems) whereas eight beds are planted with four different macrophyte species: Vetiveria zizanoides, Miscanthus x giganteus, Arundo donax and Phragmites australis. The treatment performance of each wetland has been evaluated using the load removal efficiency (LRE) in order to take into account the ET effect. The comparison between wetland treatment removal of vegetated H-SSF CWs and unplanted filters showed that systems with plants have achieved a higher treatment efficiency. ET, measured in vegetated beds, appeared different from ET of control units, underlining the strong effect of vegetation.