Tratamiento pasivo con un sustrato alcalino disperso de drenajes ácidos de mina con alta carga metálica en la cuenca del río Odiel (Faja Pirítica Ibérica, SO España)

Abstract

Many of the passive treatment systems treating acid mine drainage (AMD) have been focused on treating AMD with low to very low metal concentration as those existing, for instance, at coal mining districts. However all these passive treatment systems show severe problems of clogging or reactivity loss when exposed to AMD with high metal concentrations. To overcome all these problems we have developed a novel Dispersed Alkaline Substrate (DAS) consisting of a mixture of wood shavings (coarse inert matrix increasing hydraulic conductivity) and an alkaline reactive substrate (fine-grained limestone to raise pH and generate alkalinity). This system was under operation for a period of 20 months treating a mean inflow of 0.5 L/s. The system removed a mean net acidity of 1500 mg/L as CaC03 from the inflow water and achieved a relative removal of 100% Al, As, Cu, Pb, Cd and V, 40% Te and 15% S042-. Total removal in the reactive tank was in the range of 7.1 tonnes Te, 6.9 tonnes S042-, 2.7 tonnes Al, 0.6 tonnes Si, 0.1 tonnes Zn and 0.3 tonnes Cu