Elucidating the Potential of Vertical Flow-Constructed Wetlands Vegetated with Different Wetland Plant Species for the Remediation of Chromium-Contaminated Water

Water scarcity is one of the key global challenges affecting food safety, food security, and human health. Constructed wetlands (CWs) provide a sustainable tool to remediate wastewater. Here we explored the potential of vertical flow-CWs (VF-CWs) vegetated with ten indigenous wetland plant species to treat chromium (Cr)-contaminated water. The wetland plants were vegetated to develop VF-CWs to treat Cr-contaminated water in a batch mode. Results revealed that the Cr removal potential of VF-CWs vegetated with different wetland plants ranged from 47% to 92% at low (15 mg L-1) Cr levels and 36% to 92% at high (30 mg L-1) Cr levels, with the maximum (92%) Cr removal exhibited by VF-CWs vegetated with Leptochloa fusca. Hexavalent Cr (Cr(VI)) was reduced to trivalent Cr (Cr(III)) in treated water (96-99 %) of all VF-CWs. All the wetland plants accumulated Cr in the shoot (1.9-34 mg kg(-1) dry weight (DW)), although Cr content was higher in the roots (74-698 mg kg(-1) DW) than in the shoots. Brachiaria mutica showed the highest Cr accumulation in the roots and shoots (698 and 45 mg kg(-1) DW, respectively), followed by Leptochloa fusca. The high Cr level significantly (p < 0.05) decreased the stress tolerance index (STI) percentage of the plant species. Our data provide strong evidence to support the application of VF-CWs vegetated with different indigenous wetland plants as a sustainable Cr-contaminated water treatment technology such as tannery wastewater.

Automated summary

Water scarcity is a major global challenge impacting food safety, food security, and human health. This study explored the potential of using vertical flow constructed wetlands (VF-CWs) with different indigenous wetland plants to treat chromium (Cr)-contaminated water. The results showed that VF-CWs vegetated with certain wetland plants can effectively remove Cr from water, with removal rates ranging from 47% to 92%. The wetland plants also accumulated Cr, with higher concentrations found in the roots. This research provides evidence supporting the use of VF-CWs with indigenous wetland plants as a sustainable technology for treating Cr-contaminated water.