Performance of a Semi-passive Sulfate-reducing Bioreactor for Acid Mine Drainage Treatment and Prediction of Environment
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TECHNICAL ARTICLE
Performance of a Semi‑passive Sulfate‑reducing Bioreactor for Acid Mine Drainage Treatment and Prediction of Environmental Behavior of Post‑treatment Residues Khalifa Lounate1 · Lucie Coudert2 · Thomas Genty3 · Guy Mercier1 · Jean Francois Blais1 Received: 18 January 2020 / Accepted: 8 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The performance of a semi-passive sulfate-reducing bioreactor (SPSRB) was studied for the treatment of highly contaminated AMD (pH = 4.2, [ Fe]i: 1600 to 6400 mg/L). The potential mobility of contaminants (metals and sulfates) from AMD post-treatment residue was also evaluated (e.g. metal speciation, weathering cells) to ensure their proper management. Sodium lactate (3500 mg/L) was continuously added to three SPSRBs composed of 60% birch chips, 20% calcite, and 20% poultry manure to enhance microbial activity. The SPSRBs were very effective during the total duration of the experiment (266 days) for the removal of Fe (average removal efficiency of 97.7%), Cd (> 99.4%), Cr (99.3%), Cu (99.9%), Ni (99.2%), Pb (99.8%), Al (92.4%), and Zn (90.7%). The study of the physicochemical stability of the post-treatment residues showed a net positive neutralization potential of 22.4 kg CaCO3/t and a NP/NA ratio of 1.80. Although the metal speciation estimates revealed that Fe, Mn, Ni, and Zn were mainly retained in the biofilter as oxides or hydroxides, a significant proportion of metals were also present in the form of sulfides, or bound to organic matter as exchangeable/soluble sulfate fractions. Finally, the kinetic tests (weathering cells) confirmed the high risk of metal release if the post-treatment residues are disposed of in an oxidizing environment. Keywords Mining effluent · Biofilter · Iron · Metal · Metal speciation · Kinetic test
Introduction * Jean Francois Blais [email protected] Khalifa Lounate [email protected] Lucie Coudert [email protected] Thomas Genty [email protected] Guy Mercier [email protected] 1
Institut National de la Recherche Scientifique (Centre Eau, Terre et Environnement), Université du Québec, 490 rue de la Couronne, Québec, QC G1K 9A9, Canada
2
Institut de Recherche en Mines et en Environnement, Université du Québec en Abitibi-Témiscamingue, 445 boulevard de l‘Université, Rouyn‑Noranda, QC J9X 5E4, Canada
3
Environmental Engineer, Agnico Eagle Mines Limited, CSD, 10 200, Route de Preissac, Rouyn‑Noranda, QC J0Y 1C0, Canada
Sulfate-reducing bioreactors (SRBs) are an increasingly popular treatment option for acid mine drainage (AMD; Johnson and Hallberg 2005; Neculita et al. 2007; Nielsen et al. 2018). These biochemical treatments are based on the ability of certain type of bacteria, including sulfate-reducing bacteria, to generate alkalinity and immobilize metals as insoluble metal sulfides by the reduction of sulfate. Under anaerobic conditions, heterotrophic bacteria oxidize organic matter (electron donor) to produce the energy they need, and use sulfate as an e
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