The potential of Sedum alfredii Hance for the biosorption of some metals from synthetic wastewater

The capacity of a terrestrial Zn/Cd hyperaccumulator Sedum alfredii Hance to purify water polluted by Zn, Cd, Cu and Pb along with their removal pathway was investigated. S. alfredii Hance was grown in synthetic wastewater in 2.5-L capacity containers contaminated with (mg L−1) 19.20 Zn, 11.24 Cd, 3.27 Cu and 0.53 Pb, respectively. The supplied metal concentrations were comparable with those in plating industry wastewater. After a growth period of 7 days the average removal rates for Zn, Cd, Cu and Pb, were 94.07%, 82.33%, 96.03% and 69.61% respectively. Both root surface adsorption and absorption contributed to metal uptake. Root surface adsorption accounted for 67.74%, 24.03%, 66.53% and 70.77% of the total respective Zn, Cd, Cu and Pb, removal by S. alfredii. Addition of heavy metals stimulated the growth of S. alfredii over the control (without any addition of heavy metals) that might cause enhanced metal removal from wastewater. These results indicated promising potential of S. alfredii for remediation of a mixture of heavy metals containing wastewater. Rhizospheric microorganisms, root exudates and metal adsorption on the root surface of S. alfredii might be possible contributors in phytoremediation of Zn, Cu and Pb from wastewater.

Research Highlights
► The paper discussed the possibility of removing mixture of metals from solutions by Sedum alfredii considering adsorption on root of S. alfredii, precipitation and metal concentration change in solution with the passage of time as well as plant absorption.
► The paper also demonstrated metal adsorption mechanism by Sedum alfredii.
► The role of metal adsorption on root, absorption, and precipitation through Sedum alfredii mediated phytoremediation was discussed compared with control.