Management of acid mine drainage at Tarkwa, Ghana

Abstract

This study assesses a natural wetland in Tarkwa, south west Ghana to identify the most sustainable way to remediate acid mine drainage (AMD). The investigation involved mineralogical and bacteria analysis among others. The study traced the AMD occurrence to the presence of acid producing sulphides (pyrite) in a waste rock and the occurrence was found to be catalysed by sulphur oxidising bacteria Thiobacillus ferro-oxidans. The pH of the AMD was found to be raised from 4.4 to 7.4 in the natural wetland by Desulfovibrio desulfurican bacteria whose activity generally results in producing hydro-oxides. The restoration of pH by diverting part of a River into the wetland to dilute and neutralise the acidic effluent may not be efficient particularly during dry seasons because the flow of the dilutant is much less than the required flow to effect dilution. The study concluded that the sustainable management of AMD can be achieved through the enhancement of Desulfovibrio desulfurican activity in a constructed anaerobic wetland. © Springer Science + Business Media B.V. 2009.