Preliminary Evaluation of Metals Removal in Three Pilot-Scale Constructed Wetland Systems

The efficacy of constructed wetlands in immobilizing and removing heavy metals from tertiary treated wastewater was evaluated in pilot-scale surface flow (SF), subsurface flow (SSF), and floating aquatic plant (FAP) constructed wetland systems in central Illinois. After wetland treatment, copper concentrations declined from 56.6 mu g/l in influent to 7.9 mu g/l in the FAP system, 9.2 mu g/l in the SSF system, and 11.0 mu g/l in the SF system. Differences in concentration reduction of Cu among the three wetlands were not statistically significant. The average chromium concentration declined from 1.31 mu g/l in influent to 0.4 mu g/l in all system designs.