Sistema de tratamiento para mejorar la calidad de aguas de drenaje de pasivos ambientales mineros en la cuenca del Río Puyango (Ecuador)

Abstract

Artisan and little mining carried out in the Puyango River Basin (El Oro, SE Ecuador) causes high concentrations of toxic elements in waters derived from acid mine drainage of environmental liabilities and due to the oxidation of disseminated sulfides in these wastes. The objectives of this study are the hydrochemical characterization of the sources of pollution in the basin and also to prove an acid water treatment system to mitigate the effects of sulfide oxidation, for a future implementation under tropical climate. The results allow distinguishing two main pollutant sources, acid drainages originated in environmental liabilities and effluents from mining plants that contribute to the fluvial courses with high concentrations of sulphates and potential toxic elements. Two selected drainages were treated at laboratory scale to analyse the efficiency of passive DAS-type treatments in equatorial climates. Significant improvements were obtained in water quality after 7 months of treatment, resulting values below the international quality standards for almost all pollutants, with the exception of sulfates, Zn and Mn. The improvement in the treatment system, favouring the sulphate retention, is necessary to satisfy current regulations.