DBPapers
DOI: 10.5593/sgem2017H/33/S12.051

TRANSPORT OF HEAVY METALS THROUGH SILICA SPONGOLITE AND ACTIVATED CARBON TREATMENT ZONES

J. Fronczyk, K. Pawluk
Thursday 23 November 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgemviennagreen.org, SGEM2017 Vienna GREEN Conference Proceedings, ISBN 978-619-7408-27-0 / ISSN 1314-2704, 27 - 29 November, 2017, Vol. 17, Issue 33, 407-414 pp; DOI: 10.5593/sgem2017H/33/S12.051

ABSTRACT

This paper presents the results of column tests conducted to investigate the potential use of silica spongolite as a reactive material for the treatment of groundwater impacted by stormwater containing toxic heavy metals (Cd, Cu, Ni, Pb and Zn). Such research material was selected due to its widespread use as an aggregate in road construction. Furthermore, silica spongolite was compared with activated carbon, which is commonly used in permeable reactive barrier (PRB) technology. The column experiments were carried out in vertical columns with a diameter of 0.1 m and a height of 1.0 m using a multichannel peristaltic pump (ZALIMP) to transport the multi-component solution (20 mg/L of each heavy metal) at a constant flow rate of 4.16×10-8 m3/s (from the bottom to the top). Liquid samples for chemical analysis (pH, EC and heavy metals) were taken from the column effluent in appropriate intervals. Column test results were interpreted using the CXTFIT software package, which solves a one-dimensional advection-dispersion equation. The results have shown that the value of retardation factors (R) for activated carbon was in the order: Cu (no breakthrough) > Pb (R=66) > Cd (R=33) > Ni (R=30) > Zn (R=27). During the experiment, the concentration of Cd, Cu, Pb and Zn in the effluent solution from a column filled with silica spongolite was close to zero. The retardation factor was calculated only for nickel (R=20). Moreover, the Péclet number values (5.45 for silica spongolite and 1.20 for activated carbon) indicated the dominance of advection over dispersion.

Keywords: activated carbon, column tests, contaminants transport, heavy metals, silica spongolite