Water pollution by toxic heavy metals is a global environmental problem. It has led to the development of alternative technologies for heavy metals removal from contaminated sites. Constructed wetland microcosm by using Alocasia puber is a possible treatment method for wastewater containing heavy metals. Synthetic wastewater with heavy metals Cd, Cr, Cu, Ni, and Zn were used in this study. Several heavy metals concentrations (5 mg/L, 10 mg/L and 100 mg/L) were used in the systems. Six different hydraulic retention times (HRTs) (2, 4, 6, 8, 10 and 12 days) were tested in the present study. The results obtained showed removal efficiencies of heavy metals of >99% after day 12. The removal of Ni from 10 mg/L solutions (initial concentrations) recorded the best removal efficiency. Heavy metal translocation factor (TF) was found to be less than 1 for all metals tested, which confirmed the significance of roots as heavy metals accumulator compared to stems or leaves of A, puber. Therefore, this study concluded that A, puber has a great potential as an important component in constructed wetlands for water contaminated with heavy metals.

The contamination of water by heavy metals is a worldwide environmental problem. Phytoremediation and constructed wetlands have become increasingly popular as more sustainable and environmentally friendly techniques of removing heavy metals from the wastewater. This study, therefore, investigated the phytoremediation of nickel by Alocasia puber (A. puber) in a constructed wetlands (CW) microcosm. This study identified the optimum conditions for nickel (Ni) removal from wastewater using response surface methodology (RSM) with central composite design (CCD). Two operational variables were assessed: exposure time and initial Ni concentration. The optimum conditions for the maximum removal of Ni from water were an exposure time of 10 days and 99.76 mg/L initial Ni concentration. The results indicated that 95.6% removal was achieved under the optimized conditions, with a high correlation coefficient (R2 = 0.97) between the statistical model and the experimental data. Field emission scanning electron microscopy images showed anatomical changes in the A. puber samples due to Ni exposure, and transmission electron microscopy images revealed some internal damages in the A. puber, but visual Ni toxicity symptoms, such as necrosis and chlorosis, were not observed in the A. puber. This study demonstrated that A. puber planted in a constructed wetland microcosm was able to remediate wastewater contaminated with Ni.