An assessment of metal removal by a laboratory scale wetland

Abstract

This paper presents a preliminary assessment of the heavy metal removal performance by a laboratory scale wetland based on the design of a constructed wetland treating surface runoff. Laboratory scale gravel-substrate subsurface-flow wetlands in a continuous recirculating mode were studied regarding the removal of Cu, Pb and Zn from contaminated water. After establishing the flow characteristics, the wetland was planted with Typha latifolia, Phragmites australis, Schoenoplectus lacustris and Iris pseudacorus. The wetland system was dosed with increasing concentrations (1, 5 and 10mg/l) of Cu, Pb and Zn. Finally a shock load of metals (concentration 20 mg/l) was introduced to simulate a storm event. In each experiment water samples collected from the outlet at timed intervals were analysed and loadings calculated in order to assess the metal removal efficiency of the system. The removal efficiences and rates for these different doses ranged from 81.7% to 91.8% and 36.6 to 372.7 mg/m2/d for Cu, 75.8% to 95.3% and 30.8 to 387 mg/m2/d for Pb and 82.8% to 90.4% and 33.6 to 362.1 mg/m2/d for Zn respectively. Results for the storm simulation showed that in the time taken for the water level to subside to its original level (just below the substrate surface) at established outlet flow rates, the metal loadings leaving the system remained very low with the wetland system retaining over 99% of the metals. These results indicate the ability of the system to act as an efficient sink for heavy metals. The macrophytes were collected and segregated by species and subsurface tissue type (rhizomes, roots and root tips) and analysed for Cu, Pb and Zn. The results are discussed with respect to the surrounding peat substrate, biomass accumulation and the overall removal performance of the laboratory scale wetland.

Heavy Metal Uptake By Scirpus Littoralis Schrad. From Fly Ash Dosed and Metal Spiked Soils

“…Moreover, the uptake of all metals by Scirpus littoralis is stronger in the BO than in the shoots of this plant as shown by the mean B/S, T/S, T/B and B/W ratios. This agrees with several studies indicating that more accumulation occurs in the BO than in the shoots of the wetland plants (Mudroch, 1979;Welsh et al, 1980;Taylor et al, 1983;Babcock et al 1983;Jain et al, 1990;Sen et al, 1989;Kadelec, 1995;Mungur et al, 1997;Zayed et al, 1998;Qian et al, 1999;Sadwosky 1999;Mehra et al, 1998;Cordes et al, 2000, Mehra andZurayk 2002).…”

Constructed Wetlands: Treatment of Concentrated Storm Water Runoff (Part A)

“…Copper nitrate and nickel nitrate were added to the inflow water of Filter 2 and Filters 7 to 12 to give total concentrations of dissolved copper and nickel of approximately 1 mg/L for each metal, comparable to figures reported for urban water heavily contaminated with heavy metals and mine wastewater (Cooper et al, 1996;Kadlec and Knight, 1996;Mungur et al, 1997;Scholz and Xu, 2002).…”

“…(common reed). They are used to treat storm runoff, domestic and industrial wastewater (Cooper et al, 1996;Kadlec and Knight, 1996;Scholz, 2003), and have also been applied for passive treatment of mine wastewater drainage (Mungur et al, 1997;Mays and Edwards, 2001). …”

Assessment of the dye removal capability of submersed aquatic plants in a laboratory-scale wetland system using anova

“…There are several studies with wetland microcosms that investigated nutrient removal (Rogers et al, 1991, Drizo et al, 1997. Heavy metal removal experimentation was also established and researchers demonstrated that macrophytes, such as Typha latifolia, Phragmites australis, Schoenoplectus lacustris, and Iris pseudacorus, can be used for heavy metal removal (Mungur et al, 1997).…”