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Passive multi-unit field-pilot for acid mine drainage remediation: Performance and environmental assessment of post-treatment solid waste

2021; Elsevier BV; Volume: 291; Linguagem: Inglês

10.1016/j.chemosphere.2021.133051

1879-1298

Yaneth Vásquez, Carmen Mihaela Neculita, Gerardo Andrés Caicedo Pineda, Jairo Cubillos, Jair Franco, Mario Vásquez, Angie Lorena Hernández, Fabio Roldán,

Tailings Management and Properties

This study evaluated the performance of a passive multi-unit field-pilot operating for 16 months to treat acid mine drainage (AMD) from a coal mine in Colombia Andean Paramo. The multi-unit field-pilot involved a combination of a pre-treatment unit (550 L) filled with dispersed alkaline substrate (DAS), and six passive biochemical reactors (PBRs; 220 L) under two configurations: open (PBRs-A) and closed (PBRs-B) to the atmosphere. The AMD quality was 1200 ± 91 mg L-1 Fe, 38.0 ± 1.3 mg L-1 Mn, 8.5 ± 1.6 mg L-1 Zn, and 3200 ± 183.8 mg L-1 SO42-, at pH 2.8. The input and output effluents were monitored to establish AMD remediation. Physicochemical stability of the post-treatment solids, including metals (Fe2+, Zn2+, and Mn2+) and sulfates for environmental contamination from reactive mixture post-treatment, was also assessed. The passive multi-unit field-pilot achieved a total removal of 74% SO42-, 63% Fe2+, and 48% Mn2+ with the line of PBRs-A, and 91% SO42-, 80% Fe2+, and 66% Mn2+ with the line of PBRs-B, as well as 99% removal for Zn2+ without significant differences (p < 0.05) between the two lines. The study of the physicochemical stability of the post-treatment solids showed they can produce acidic leachates that could release large quantities of Fe and Mn, if they are disposed in oxidizing conditions; contact with water or any other leaching solutions must be avoided. Therefore, these post-treatment solids cannot be disposed of in a municipal landfill. The differences in configuration between PBRs, open or closed to the atmosphere, induced changes in the performance of the passive multi-unit field-pilot during AMD remediation.