naa a22 4500 510751555 CHVBK 20180411083106.0 cr unu---uuuuu 180411e20130401xx s 000 0 eng 10.1007/s11270-013-1521-5 doi (NATIONALLICENCE)springer-10.1007/s11270-013-1521-5 Acid Mine Drainage Treatment Assisted by Lignite-Derived Humic Substances [Elektronische Daten] Metal Removal and Speciation Modelling [William Olds, Daniel Tsang, Paul Weber] Acid mine drainage (AMD) generated by some coal mines in New Zealand is currently treated by the addition of alkaline reagents which neutralize acidity, triggering the precipitation of dissolved metals as insoluble hydroxides. Some trace metals (Ni, Zn, Cu, Cd, and Pb) are discharged into receiving water bodies due to incomplete hydroxide precipitation at circum-neutral pH. This study investigated the incorporation of lignite-derived humic substances (HS) for metal complexation and removal during AMD treatment by Ca(OH)2 and CaCO3 neutralization. For Ca(OH)2 neutralization, addition of HS (regardless of dosing sequence) enhanced the removal of Zn, Cu, and Cd, probably due to the incorporation of metal-humate complex into settling flocs (via aggregation, co-precipitation, and adsorption) that were subsequently removed by sedimentation. However, additional removal of Ni and Pb was statistically indeterminate, which was ascribed to the low complexation affinity of Ni and high removal of Pb by adsorption onto Fe/Al hydroxides. Conversely, for CaCO3 neutralization, addition of HS only marginally enhanced Cd removal, with the removal of metals probably dominated by adsorption onto the abundant undissolved calcite. Equilibrium speciation modelling showed that about 25% and 38% of the remaining Cu and Pb in the treated AMD were complexed with HS, while only 5% of remaining Cd and less than 1 wt% of remaining Ni and Zn were organically complexed. In the AMD-receiving water bodies, about 20 mg l−1 of HS would be required for complete complexation (>95%) of Cu and Pb and 50 mg l−1 for Cd, whereas Zn and Ni complexation would not occur at natural stream HS concentrations. Springer Science+Business Media Dordrecht, 2013 Mine drainage nationallicence Equilibrium speciation nationallicence Humic substances nationallicence Metal complexation nationallicence Olds William Department of Civil and Natural Resources Engineering, University of Canterbury, 8140, Christchurch, New Zealand aut Tsang Daniel Department of Civil and Natural Resources Engineering, University of Canterbury, 8140, Christchurch, New Zealand aut Weber Paul Solid Energy New Zealand Ltd, Private Bag, 1303, Christchurch, New Zealand aut Water, Air, & Soil Pollution Springer Netherlands 224/4(2013-04-01), 1-12 0049-6979 224:4<1 2013 224 11270 https://doi.org/10.1007/s11270-013-1521-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11270-013-1521-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Olds William Department of Civil and Natural Resources Engineering, University of Canterbury, 8140, Christchurch, New Zealand aut NATIONALLICENCE 700 1- Tsang Daniel Department of Civil and Natural Resources Engineering, University of Canterbury, 8140, Christchurch, New Zealand aut NATIONALLICENCE 700 1- Weber Paul Solid Energy New Zealand Ltd, Private Bag, 1303, Christchurch, New Zealand aut NATIONALLICENCE 773 0- Water, Air, & Soil Pollution Springer Netherlands 224/4(2013-04-01), 1-12 0049-6979 224:4<1 2013 224 11270 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer