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J Contam Hydrol. 2015 Jun-Jul;177-178:76-84. doi: 10.1016/j.jconhyd.2015.03.007. Epub 2015 Mar 26.

Geochemical modelling for predicting the long-term performance of zeolite-PRB to treat lead contaminated groundwater.

Author information

1
Department of Geology and Environmental Protection, Hydrogeotechnika Sp z o.o., ul.Sciegiennego 262A, 25-112 Kielce, Poland. Electronic address: franklin.obiri.nyarko@hydrogeotechnika.pl.
2
Department of Spatial Planning and Environmental Sciences, Faculty of Geodesy and Cartography, Warsaw University of Technology, Pl Politechniki 1, 00-661 Warsaw, Poland.
3
AGH University of Science and Technology, Department of Hydrogeology and Engineering Geology, Al. Mickiewicza 30, 30-059 Krakow, Poland.
4
Department of Geology and Environmental Protection, Hydrogeotechnika Sp z o.o., ul.Sciegiennego 262A, 25-112 Kielce, Poland.

Abstract

The feasibility of using geochemical modelling to predict the performance of a zeolite-permeable reactive barrier (PRB) for treating lead (Pb(2+)) contaminated water was investigated in this study. A short-term laboratory column experiment was first performed with the zeolite (clinoptilolite) until the elution of 50 PV (1 PV=ca. 283 mL). Geochemical simulations of the one-dimensional transport of the Pb(2+), considering removal processes including: ion-exchange, adsorption and complexation; the concomitant release of exchangeable cations (Ca(2+), Mg(2+), Na(+), and K(+)) and the changes in pH were subsequently performed using the geochemical model PHREEQC. The results showed a reasonable agreement between the experimental results and the numerical simulations, with the exception of Ca(2+) for which a great discrepancy was observed. The model also indicated the formation of secondary mineral precipitates such as goethite and hematite throughout the experiment, of which the effect on the hydraulic conductivity was found to be negligible. The results were further used to extrapolate the long-term performance of the zeolite. We found the capacity would be completely exhausted at PV=250 (ca. 3 days). The study, thus, generally demonstrates the applicability of PHREEQC to predict the short and long-term performance of zeolite-PRBs. Therefore, it can be used to assist in the design and for management purposes of such barriers.

KEYWORDS:

Column experiment; Lead; Long-term performance; PHREEQC; Permeable reactive barriers; Zeolite

PMID:
25863218
DOI:
10.1016/j.jconhyd.2015.03.007
[Indexed for MEDLINE]

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