Fate of heavy metals in vertical subsurface flow constructed wetlands treating secondary treated petroleum refinery wastewater in Kaduna, Nigeria

Abstract

This study examined the performance of pilot-scale vertical subsurface flow constructed wetlands (VSF-CWs) planted with three indigenous plants, i.e. Typha latifolia, Cyperus alternifolius, and Cynodon dactylon, in removing heavy metals from secondary treated refinery wastewater under tropical conditions. The T. latifolia-planted VSF-CW had the best heavy metal removal performance, followed by the Cyperus alternifolius-planted VSF-CW and then the Cynodon dactylon-planted VSF-CW. The data indicated that Cu, Cr, Zn, Pb, Cd, and Fe were accumulated in the plants at all the three VSF-CWs. However, the accumulation of the heavy metals in the plants accounted for only a rather small fraction (0.09-16%) of the overall heavy metal removal by the wetlands. The plant roots accumulated the highest amount of heavy metals, followed by the leaves, and then the stem. Cr and Fe were mainly retained in the roots of T. latifolia, Cyperus alternifolius, and Cynodon dactylon (TF < 1), meaning that Cr and Fe were only partially transported to the leaves of these plants. This study showed that VSF-CWs planted with T. latifolia, Cyperus Alternifolius, and Cynodon dactylon can be used for the large-scale removal of heavy metals from secondary refinery wastewater.

Application of Floating Aquatic Plants in Phytoremediation of Heavy Metals Polluted Water: A Review

“…The phytoremediation potential of three aquatic wetland plants i.e., Cyperus alternifolius, Cynodon dactylon and Typha latifolia, was examined for the transfer and translocation of HMs from the root zone to upper parts of the body in a constructed wetland receiving refinery wastewater. Results affirmed that the highest concentration of Cr, Zn, Cd, Pb and Fe were accumulated by roots of the plants followed by leaves and stem [326]. Similarly, Typha latifolia showed maximum removal efficiency of 96%, 95% and 80% for Cd, Cr and Pb correspondingly in a laboratory-scale constructed wetland unit.…”

Phytoremediation potential of Bacopa monnieri in the removal of heavy metals

“…High concentration of metal ions in the root indicates that element compartmentalization, tolerance strategy by the plant in respect to the different metal ions and the level of concentration (Hazra et al, 2015;Zengin and Munzuroglu, 2005). This tolerance strategy is common in wetland plants and helps the plant to protect photosynthetic tissues in the above ground parts from the harmful effects of toxic metal ions (Wang et al, 2002;Akinbile, 2016;Mustapha, 2018). Presence of higher metal concentration in below ground parts of the plant was patterned with most authors (Victor et al, 2016, Ton et al, 2015, Saxena and Saiful-Arfeen, 2009.…”

Optimization of Phytoremediation of Nickel by Alocasia puber Using Response Surface Methodology

“…Approximately 0.5 g of each sample was added to 10 mL of HNO 3 (65%) (Merck, Kenilworth, NJ, USA) for acid digestion. The concentration of heavy metals in the plant samples were analysed using an atomic absorption spectrophotometer (AAS) [30].…”