Eco-sustainable passive treatment for mine waters: Full-scale and long-term demonstration

Abstract This paper tries to analyse the technical and economic performance of a full-scale passive Disperse Alkaline Substrate (DAS) treatment plant steadily operating for 28 months (840 days) treat extremely acidic metal rich mine waters in Iberian Pyrite Belt (SW Spain). For first time, an evaluation this technology its comparison with other treatments is reported. During period, around 56,000 m3 have been treated, without significant clogging or exhaustion alkaline substrate. The efficiency system demonstrated by decrease average net acidity (from 2005 −43 mg/L as CaCO3 equivalent) total elimination Al, Cu, REY, Zn, As, Cr, Mo, V, Cd, Pb, Co trace metals. Water quality treated output discharge meets threshold values irrigation drinking standards, except Fe, Mn sulphate. accumulation elements interest waste (e.g., 32 t 6.1 t 0.8 t 39.4 kg REE, 20 kg 1 kg Sc), easily extractable diluted acids, may turn hazardous into valuable resource. benefits associated revalorization metal-rich could reach 27478 USD, but more reliably estimated be 8243 USD due technologic limitations. benefit would help defray maintenance costs (8428 €) make DAS economically self-sustainable treatment. annual cost was 0.27 €/m3, being lowest value found among reported conventional schemes, from 8 12 times lower compared active technologies. results obtained prove that most technically sustainable way decontaminate acid abandoned mines.