Differences in the removal mechanisms of Undaria pinnatifida and Phragmites australis as biomaterials for lead removal

This study offers the opportunity to utilize Undaria pinnatifida and Phragmites australis to remove lead from water in permeable reactive barrier (PRB) technology. Its efficacy was tested using batch experiments and PRB column systems. From the batch experiment results, a higher adsorption capacity was observed for Undaria pinnatifida. Nevertheless, Phragmites australis in the column system efficiently removed lead and the breakthrough occurred at the same time for both biomaterials. To dissipate this difference, a sequential extraction for metal speciation analysis was used for both columns. The results have shown that each biomaterial has a dominant mechanism. Phragmites australis removed lead by physical adsorption, whereas Undaria pinnatifida showed a higher tendency to bind lead due to organic matter, primary and secondary minerals.