Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/13008
Title: Acid mine drainage treatment assisted by lignite-derived humic substances : metal removal and speciation modelling
Authors: Olds, WE
Tsang, DCW 
Weber, P
Keywords: Equilibrium speciation
Humic substances
Metal complexation
Mine drainage
Issue Date: 2013
Publisher: Springer
Source: Water, air, & soil pollution, 2013, v. 224, no. 4, 1521 How to cite?
Journal: Water, air, & soil pollution 
Abstract: 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.
URI: http://hdl.handle.net/10397/13008
ISSN: 0049-6979
EISSN: 1573-2932
DOI: 10.1007/s11270-013-1521-5
Appears in Collections:Journal/Magazine Article

Access
View full-text via PolyU eLinks SFX Query
Show full item record

SCOPUSTM   
Citations

10
Last Week
0
Last month
0
Citations as of Sep 24, 2017

WEB OF SCIENCETM
Citations

9
Last Week
0
Last month
0
Citations as of Sep 22, 2017

Page view(s)

48
Last Week
0
Last month
Checked on Sep 25, 2017

Google ScholarTM

Check

Altmetric



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.