International Journal of Environmental Sciences

Volume 7 Issue 1 2016- July 2016 Pages: 49 - 61                                 Next>>

Potential for reuse of gold mine tailings as secondary construction materials and Phytoremediation

Author Information:

Restituta P. Mapinduzi1, Pancras M.S. Bujulu2, William J.S. Mwegoha3
1,2- College of Engineering and Technology, University of Dar es Salaam, P. O. Box 35131, Dar es Salaam, Tanzania
3- School of Environmental Sciences and Technology, College of Earth Sciences, University of Dodoma, P. O. Box 259, Dodoma, Tanzania

ABSTRACT

The potential for re-use of gold mine tailings as secondary construction materials and in phytoremediation was investigated using tailings from Geita and Bulyanhulu gold mines in Tanzania. Properties investigated include particle size, permeability, pH, electrical conductivity, cation exchange capacity, organic matter content, soil/plant nutrient content and heavy metal content. Through laboratory tests, tailings have been classified as alkaline silt materials of low plasticity with low organic and nitrogen contents (1.99 - 2.45) % and (0.9 - 1.0) mg/kg respectively. The cation exchange capacity of these materials varies from 6.0 to7.5 meq/100g and is dependent on clay content. The pH varies from 7.2 to 7.5, typical for soils with large amounts of Ca2+ and Mg2+. The major tailings oxides are SiO2, which form more than 50% w/w, Al2O3 (9.61 to 14.60), Fe2O3 (10.4 to 17.47), and SO3 (11.40 to 12.10). Cd2+ concentration in samples from both sites and Cu2+ and Pb2+ in sample from Bulyanhulu are above permissible toxicity levels for soil and plants. Zn2+ and Cd2+ concentrations exceed their respective predicted No Observable Adverse Effect Levels (NOAEL) for plants and soil organisms. In general, tailings sample from Bulyanhulu is more contaminated, and has less potential for phytoremediation compared to the one from Geita. Based on these findings, it is concluded that physical and chemical properties support the potential of tailings for use as a construction materials, supported by the abundance of quarts which enhances resistance to extreme weather conditions and durability. Nevertheless, low mineral nutrient levels and associated physical properties hinders the potential of these materials for use in phytoremediation. Enhancement of phytoremediation potential for gold mine tailings can be achieved through amendments with Terminal Electron Acceptors (TEA) in order to improve cation exchange properties.

Keywords: Bioremediation, construction; heavy metals; phytoremediation; tailings

DOI:10.6088/ijes.7005

© 2016 Copyright by the authors, licensee Integrated Publishing Association.This is an open access article distributed under the Creative Commons Attribution License (3.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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