Cadmium Removal from Wastewater in Constructed Wetlands

Abstract

This study was conducted to investigate the cadmium removal in the free water surface and subsurface flow constructed wetland systems under different environmental conditions. Removal efficiencies of the chemical oxygen demand were found to be in the range of 79–92% for the two wetland systems. The removal efficiencies for total kjeldahl nitrogen, total phosphorus, total suspended solid, and volatile suspended solid were in the range of 64–91, 62–90, 68–91, and 50–84%, respectively. Influents were obtained by mixing a synthetic wastewater with Cd Cl2 . H2 O at four concentrations 1, 5, 10, and 20 mg∕L , respectively, for the four experimental runs. The mean effluent cadmium concentrations varied between 0.02 and 0.16 mg∕L . Cadmium removal efficiencies were 98.6–99.4% in free water surface, and 99.3–99.9% in the subsurface flow wetland systems. The subsurface flow wetland showed slightly better performance than the free water surface wetland in terms of various pollutants’ removal. However, the two system...