Removal of alkali metals and their sequestration in plants in constructed wetlands treating municipal sewage

Abstract

This study is aimed at retention of K, Na, Mg, and Ca in two constructed wetlands (CWs) in the Czech Republic, and on the evaluation of particular standing stocks in both above-and belowground plant biomass. The study revealed that CWs with horizontal subsurface flow are not effective in retention of studied elements. Removal of K, Na, Mg, and Ca averaged only 10.6, 7.4, 6.1, and 1.4%, respectively. In general, concentrations of studied elements in various parts of Phragmites australis and Phalaris arundinacea were found within the range of concentrations reported from both natural and CWs. Aboveground standing stocks for K, Na and Mg were comparable with those reported from natural stands for both Phalaris and Phragmites, but Ca aboveground standing stocks found in our study were lower compared to those found in several natural Phragmites wetlands. Aboveground to belowground standing stock ratio was generally [1.0. However, this amount formed usually \1% of the annual inflow load of particular elements. The results of this study provide comprehensive information on retention and sequestration of K, Na, Mg, and Ca in vegetation during municipal wastewater treatment in CWs with subsurface horizontal flow.

Trace metal concentrations and their transfer from sediment to leaves of four common aquatic macrophytes

“…In spite of the fact that Ca and K contents in certain species were higher than natural (Kabata-Pendias and Pendias 2001; Markert 1992), the concentrations were lower than reported previously in helophytes from anthropogenic areas (Samecka-Cymerman and Kempers 2001; Vardanyan and Ingole 2006). In Phragmites australis and Phalaris arundinacea, Ca concentrations were higher while Na lower than in these species growing in municipal sewage wetland (Vymazal and Sveha 2012). The relatively high enrichment factors (Table 3), indicating high accumulation of these elements, were expected because alkali cations are essential for many metabolic processes and the plant growth and therefore are preferentially allocated in transpiring organs -plant leaves (Barker and Pilbeam 2007).…”

Reuse of urban-treated wastewater from a pilot-scale horizontal subsurface flow system in Sicily (Italy) for irrigation of Bermudagrass (Cynodon dactylon (L.) Pers.) turf under Mediterranean climatic conditions

“…Maine et al [49] reported the removal of 34, 5, 5 and 34% for Ca, K, Mg and Na, respectively, in a FWS CW in Argentina. Vymazal and Šeha [50] claimed that HSSFs were not effective in retentions of the studied elements and reported removal of Ca, K, Mg and Na averaged only 1.4, 10.6, 6.1 and 7.4%, respectively, in two HSSF CW in the Czech Republic. Cooper and Findlater [51] highlight that in the CWs the main processes for the remove of metals are sedimentation, filtration, precipitation, adsorption and biological reactions.…”

Phytoremediation in Constructed Wetlands

“…Phragmites australis has been identified as the most suitable emergent plant species for toxic metal ion removal (Marchand et al 2010), but the performance of Phalaris arundinacea is very much similar to Phragmites australis as do Typha domingensis, Typha latifolia, and Phragmites karka (Maine et al 2009;Marchand et al 2010;Vymazal 2007). Phragmites australis and Phalaris arundinacea species have also been used for treating alkali metals such as Na, Mg, K, and Ca, and the results of this study provide comprehensive information on the retention and sequestration of such alkali metals in vegetation during municipal wastewater treatment in constructed wetlands with subsurface horizontal flow (Vymazal and Šveha 2012). Phragmites australis is an invasive species in the Northeast USA that sequesters more metals belowground than the native Spartina alterniflora (Weis and Weis 2004).…”

“…It has been investigated that some of macrophytes such as Typha, Phragmites, Eichhornia, Azolla, Lemna, Glyceria grandis, Scirpus validus, Spartina pectinata, etc., are capable of uptake and accumulate a variety of heavy metals (e.g., Cd, Pb, Cr, Zn, Hg, Ni, etc.) and metalloids (e.g., Se) that are present within high concentrations in wastewater (de Souza et al 1999;Lin and Terry 2003;Cheng et al 2002;Deng et al 2004;Karathanasis and Johnson 2003;Liao and Chang 2004;Maine et al 2009;Stottmeister et al 2003;Türker et al 2014;Vymazal and Šveha 2012;Weis and Weis 2004;Ye et al 2001). Some macrophytes can be used to treat more than one metal, and these plants can accumulate heavy metals in concentrations 100,000 times greater than in the associated water (Marchand et al 2010).…”