SREL Reprint #3506

The performance of a free surface and metal-removing constructed wetland: How a young wetland becomes mature

Xiaoyu Xu1, Gary Mills1, Angela Lindell1, Erin Peck1, Alexis Korotasz2, and Elizabeth Burgess3

1Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, USA
2Department of Integrative Biology, University of South Florida, FL, USA
3University of South Carolina Aiken, Aiken, SC, USA

Abstract: The H-02 wetland was constructed on the Savannah River Site (SC, USA) in 2007 to remove Cu and Zn from process and storm runoff water. Water samples were routinely collected from 2008 to 2017 in the primary discharge pipes, influent, effluent, and receiving stream. Water quality parameters were measured in situ, total and dissolved metal (Cu and Zn) concentrations were determined, and metal speciation was calculated with the Biotic Ligand Model. Generally, the H-02 wetland system functioned well during the reporting period. Alkaline waters in the pipe became neutral after running through the wetland. Total metal concentrations in the effluent were lower than the regulatory discharge limit with a removal efficiency of 63.8% (95% CI: 60.8–66.8%) for Cu and 70.5% (95% CI: 67.0–73.9%) for Zn. Reduced metal toxicity was inferred from the observed lower concentrations of free Cu2+ and Zn2+ in the effluent than that in the influent and pipe. As suggested by the higher percentage of Cu-organic matter complexes than Zn-organic matter complexes, Cu had a higher affinity for natural organic ligands than Zn. A three-stage performance pattern of a metal-removing constructed wetland was hypothesized, which includes the plateau stage, the trough stage, and the recovery stage. Further studies were needed to test this hypothesis, monitor the treatment efficiency, improve operation strategies, and ensure the long-term sustainability of H-02 wetland system.

Keywords: Constructed wetland; Copper; Metal speciation; Removal efficiency; Zinc

SREL Reprint #3506

Xu, X., G. L. Mills, A. H. Lindell, E. Peck, A. M. Korotasz, and E. A. Burgess. 2019. The performance of a free surface and metal-removing constructed wetland: How a young wetland becomes mature. Ecological Engineering 133(2019): 32-38.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).