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Constructed wetlands (CWs) have emerged as effective biotechnological solutions for wastewater treatment in recent decades. While plants are recognized components of these systems, their specific role in nutrient and heavy metal (HM) uptake warrants further investigation. This study assesses the efficacy of a vertical flow constructed wetland (VFCW) unit planted with Phragmites australis in treating HM-laden wastewater. Through standard methods, wastewater samples from inlet and outlet were analyzed for HMs (Cd, Zn, Pb, Cu), alongside plant and sediment samples. Planted CWs demonstrated remarkable removal efficiencies: 89.34% for Cd, 76.27% for Zn, 68.14% for Cu, and 66.42% for Pb, surpassing unplanted systems (18.27% to 33.16% removal). Notably, P. australis exhibited strategic pollutant absorption, with highest HM concentrations below-ground. Though above-ground HM accumulation was relatively minor, it exceeded soil concentrations. Analysis of accumulation factors confirmed roots and rhizomes as primary bio-accumulators, with transfer factor values (Cd > Pb > Zn > Cu) indicating efficient uptake. These findings underscore the pivotal role of P. australis in enhancing HM removal within VFCW systems, emphasizing the importance of plant-based strategies in HM remediation. Recommendations include further exploration of plant-assisted methods to optimize HM treatment in CWs.
Tlili et al. (Tue,) studied this question.