From highly polluted Zn-rich acid mine drainage to non-metallic waters: Implementation of a multi-step alkaline passive treatment system to remediate metal pollution

• Published in: The Science of the total environment Vol. 433; pp. 323 - 330
• Main Authors: Macías, Francisco, Caraballo, Manuel A., Rötting, Tobias S., Pérez-López, Rafael, Nieto, José Miguel, Ayora, Carlos
• Format: Journal Article Publication
• Language: English
• Published: Kidlington Elsevier B.V 01.09.2012; Elsevier
• Subjects: Acid mine drainage; Applied sciences; Aqüífers; Brucite; Caustic magnesia; Contaminació; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Enginyeria civil; Environmental Restoration and Remediation - methods; Exact sciences and technology; Geologia; Groundwater; Groundwaters; Hidrologia subterrània; Hydrozincite; Industrial wastewaters; Metal pollution remediation; Microscopy, Electron, Scanning; Mining; Natural water pollution; Pollution; Pollution, environment geology; Wastewaters; Water Pollutants, Chemical - analysis; Water treatment and pollution; Zinc - analysis; Àrees temàtiques de la UPC; Europe; Spain; Caustic magnesia; Hydrozincite; Acid mine drainage; Metal pollution remediation; Brucite; Microbial activity; Dissolution; Heavy metal; Trace element; Decontamination; Old mine; Industrial waste water; Water pollution; Bioremediation; Waste water purification; Ground water
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2012.06.084

Complete metal removal from highly-polluted acid mine drainage was attained by the use of a pilot multi-step passive remediation system. The remediation strategy employed can conceptually be subdivided into a first section where the complete trivalent metal removal was achieved by the employment of a previously tested limestone-based passive remediation technology followed by the use of a novel reactive substrate (caustic magnesia powder dispersed in a wood shavings matrix) obtaining a total divalent metal precipitation. This MgO-step was capable to abate high concentrations of Zn together with Mn, Cd, Co and Ni below the recommended limits for drinking waters. A reactive transport model anticipates that 1m3 of MgO-DAS (1m thick×1m2 section) would be able to treat a flow of 0.5L/min of a highly acidic water (total acidity of 788mg/L CaCO3) for more than 3years. ► Complete metal removal was attained by a pilot multi-step passive remediation system. ► Outflowing metal concentration is decreased below the limits for drinking waters. ► A reactive transport model successfully matched the experimental breakthrough data. ► The reactive transport model points out the long-term performance of the system. ► The treatment pilot plant should be considered by the authorities for full scale use.