Performances of Two Macrophytes Species in Floating Treatment Wetlands for Cadmium, Nickel, and Zinc Removal from Urban Stormwater Runoff

Abstract

International audienceConventional stormwater detention ponds frequently show limitations for dissolved heavy metal removal. Floating treatment wetlands (FTWs), a variant of constructed wetlands, are considered as a promising technology to improve the quality of urban stormwater runoff. Our study aimed at evaluating the treatment performances of FTWs for cadmium, nickel, and zinc removal through a pot experiment. Two macrophytes species, Juncus effusus and Carex riparia, were grown during 4 months under three metal concentrations (in micrograms per liter): high (Cd, 200; Ni, 500; Zn, 2,000), low (Cd, 10; Ni, 10; Zn, 40), and control (Cd-Ni-Zn, 0). Results showed that both macrophytes species significantly removed dissolved heavy metals. Cadmium and nickel accumulations were greater in roots than in shoots for both species. Under low metal concentration, maximum accumulation of 0.4 mu g g(-1) dry weight (DW) for Cd was observed in the roots of J. effusus. Under high metal concentration, accumulations of up to 5 mu g Cdg(-1) DW and 62 mu g Nig(-1) DW were observed in the roots of J. effusus and up to 73 mu g Zng(-1) DW in the roots of C. riparia. Although J. effusus and C. riparia are not recognized as metal hyperaccumulators, our study demonstrated that they can achieve high metal uptake when both roots and shoots are harvested

Floating treatment wetlands for heavy metal removal in highway stormwater ponds

“…The ability of a floating marsh to overcome this constraint was demonstrated during the experiment, when rainfall from several storms increased the pond's water level by several centimeters. Both rooted macrophytes used in this study, J. effusus and C. riparia, have previously demonstrated their ability to grow in a hydroponic system, however, total nutrient resources were assumed to be less favorable than those applied in a prior study conducted in microcosms (Ladislas et al, 2013). Not surprisingly, biomass production was lower in the stormwater pond than in microcosm experiments.…”

“…To our knowledge, the role played in the decontamination process by the microbial biofilm that develops on the surface of roots suspended in the water column has been little studied. Previous research has shown that Juncus and Carex are able to grow and accumulate Ni, Cd, and Zn under hydroponic conditions in the laboratory (Ladislas et al, 2013).…”

“…J. effusus and C. riparia (Ladislas et al, 2013), under real conditions; and -to measure microbiological activity on the root surface, in order to understand the possible role played by microbial biofilm in pollutant removal.…”

Removal of Selected Metals from Wastewater Using a Constructed Wetland

“…In addition to precipitation and adsorption in sediments, the accumulation in wetland plants has to be regarded as the complementary mechanism of cobalt and nickel removal as reported by Ladislas et al . .…”

Removal of selected risk elements from wastewater in a horizontal subsurface flow constructed wetland

“…It can be removed by plant uptake as well (Ladislas et al . ). Kumari & Tripathi () observed that Phragmites australis showed higher accumulative capacity for Cd than Typha latifolia .…”