EJMP&EP





Biosorption of heavy metals from leachates generated at mine waste disposal sites

I.G. Petrisor1*, K. Komnitsas2, I. Lazar3, A. Voicu3, S. Dobrota3, M. Stefanescu3

1 Department of Civil and Environmental Engineering, University of Southern California, 3620 S. Vermont Ave., KAP 210 - MC 2531, Los Angeles, CA 90089-2531, USA
2 National Technical University of Athens, Zografou Campus, 15780 Athens, Greece
3 Institute of Biology of Romanian Academy, Spl. Independentei 296, CP 56-53, Sector 6, 79651 Bucharest, Romania

Received 27 March 2002; accepted 10 September 2002



ABSTRACT

In the present paper, the efficiency of adsorbents and biosorbents for the removal of metal ions and the clean up of leachates, generated at two Romanian mine waste disposal sites is examined. Several adsorbents such as activated charcoal, molecular sieve, shell sand, diatomite, bentonite, kaolin, as well as biosorbents such as xanthan biopolymer and waste biomasses are assessed, in terms of metal ion removal efficiency, in laboratory glass columns, comprising layers of coarse sand and 3 layers of each adsorbent/biosorbent. The effect of immobilized bacterial cells (naturally occurring consortia of acidophilic heterotrophic and chemolithotrophic bacteria) was also studied. The experimental results show that shell sand, molecular sieve and waste biomass have a relatively high efficiency in removing most heavy metal ions present in low pH leachates. Regarding shell sand and for the experimental conditions used, the selectivity follows the order Pb>As>Cd>Ni>Cu>Zn>Al>Co>Mn. From the two types of the isolated from leachates inoculum used as immobilized biomass, only heterothrophic acidophilic bacteria had a positive effect on metal uptake in contrary to chemolithotrophic acidophilic bacteria. The sufficient metal removal efficiency attained even without the use of immobilized bacteria, is mainly due to the stimulation of naturally occurring microbiota by addition of culture media; this stimulation may be considered as a feasible alternative to the use of immobilized cells in biosorption applications, regardless of the type of adsorbent/biosorbent used and the metal ion in concern.


Keywords: Biosorption; Shell sand; Heavy metals; Leachates



* Corresponding Author
   E-mail : petrisor@usc.edu