Removal of Selected Metals from Wastewater Using a Constructed Wetland

Abstract

Removal of selected metals from municipal wastewater using a constructed wetland with a horizontal subsurface flow was studied. The objective of the work was to determine the efficiency of Cu, Zn, Ni, Co, Sr, Li, and Rb removal, and to describe the main removal mechanisms. The highest removal efficiencies were attained for zinc and copper (89.8 and 81.5%, respectively). It is apparently due to the precipitation of insoluble sulfides (ZnS, CuS) in the vegetation bed where the sulfate reduction takes place. Significantly lower removal efficiencies (43.9, 27.7, and 21.5%) were observed for Li, Sr, and Rb, respectively. Rather, low removal efficiencies were also attained for Ni and Co (39.8 and 20.9%). However, the concentrations of these metals in treated water were significantly lower compared to Cu and Zn (e.g., 2.8 ± 0.5 and 1.7 ± 0.3 μg/l for Ni at the inflow and outflow from the wetland compared to 27.6 ± 12.0 and 5.1 ± 4.7 μg/l obtained for Cu, respectively). The main perspective of the constructed wetland is the removal of toxic heavy metals forming insoluble compounds depositing in the wetland bed. Metal uptake occurs preferentially in wetland sediments and is closely associated with the chemism of sulfur and iron.

A Bibliometric Analysis of Research on Selenium in Drinking Water during the 1990–2021 Period: Treatment Options for Selenium Removal

“…The design of constructed wetlands is a valuable green option to apply the potential of these plants for improving water quality. The main mechanisms for removal of selenium in constructed wetlands include biosorption, biologically-mediated precipitation, assimilation and accumulation, and volatilization of organic selenium compounds produced via bioalkylation [292]. The relative contribution of each pathway and the precise roles of the plants, the corresponding microorganisms and even the animals that may be present depends on the specific biotic community and the abiotic conditions in the constructed wetland.…”

Highly efficient nickel (II) removal by sewage sludge biochar supported α-Fe2O3 and α-FeOOH: Sorption characteristics and mechanisms

“…So far, numerous attempts were made to eliminate Ni contamination, including chemical precipitation [4], phytoremediation [5], redox [6] and adsorption [7, 8]. Among them, adsorption is an effective technology for Ni removal and potentially for Ni recycle based on desorption [9].…”

An Overview to Technical Solutions for Molybdenum Removal: Perspective from the Analysis of the Scientific Literature on Molybdenum and Drinking Water (1990–2019)

“…Indeed, the largest fraction of molybdenum retained was the water-soluble fraction on the surface of the pyrite. The removal of selected risk metals (Pb, Cd, Cr, Mo, V, Be and Ba) from municipal wastewater using a horizontalsubsurface-flow constructed wetland was studied [139,140]. The system consisted of a storm overflow, a pretreatment (screens, horizontal sand trap and sedimentation basin) and two vegetated beds planted with common reed (Phragmites australis).…”