Evaluation of single and multilayered reactive zones for heavy metals removal from stormwater

Abstract

In this paper, the ability of granular activated carbon (GAC), silica spongolite (SS) and zeolite (Z) to remove heavy metals from aqueous solutions has been investigated through column tests. The breakthrough times for a mobile tracer that does not sorb to the material for SS, GAC and layered SS, Z and GAC were as follows: 2.54×10⁴ s, 2.38×10⁴ s and 3.02×10⁴ s. The breakthrough time (t_bR) for Ni was in the range from t_bR = 1.70×10⁶ s for SS, through t_bR = 3.98×10⁵ s for the layered bed, to t_bR = 8.75×10⁵ s for GAC. The breakthrough time for Cd was in the range from t_bR = 1.83×10⁵ s for GAC to t_bR = 1.30×10⁶ s for SS, Z, GAC. During the experiment, the concentration of Cd, Cu, Pb and Zn in the solution from a column filled with construction aggregate and the concentration of Pb, and Cu in a filtrate from the column filled with several materials was close to zero. The reduction in metal ions removal was due to high pH values of the solution (above 8.00). In addition, during the testing period, an increase in Cd and Zn concentrations in the filtrate from the column filled with the layered bed was observed, but at the end of the experiment the concentrations did not reach the maximum values. The test results suggest that the multilayered permeable reactive barrier is the most effective technology for long time effective removal of heavy metals.

Keywords:

• permeable reactive barrier
• reactive materials
• heavy metals sorption
• activated carbon
• silica spongolite

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was supported by the National Science Centre, Poland [under grant number N N523 561638] and the European Union funds by the European Social Fund.