Capacity of Wood Ash Filters to Remove Iron from Acid Mine Drainage: Assessment of Retention Mechanism
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TECHNICAL ARTICLE
Capacity of Wood Ash Filters to Remove Iron from Acid Mine Drainage: Assessment of Retention Mechanism Thomas Genty • Bruno Bussie`re • Mostafa Benzaazoua Ge´rald J. Zagury
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Received: 5 December 2011 / Accepted: 1 August 2012 / Published online: 19 August 2012 Ó Springer-Verlag 2012
Abstract Acid mine drainage (AMD) with high iron concentrations can be a major challenge for passive treatment systems, particularly when sulphate reducing passive bioreactors (SRPBs) are used. The capacity of wood ash filters to act as a polishing step after SRPB treatment of a high-iron AMD (4,000 mg L-1 of Fe) was assessed. Five columns (1.7 L) with different mixtures of wood combustion ash and sand were investigated for their potential to remove metals from an SRPB effluent over 122 days. These materials had a high specific surface area (between 46 and 159 m2 g-1), high organic carbon contents (between 12 and 32 %), and a high paste pH (up to 12.2). The Freundlich isotherm model reflects the observed iron sorption behavior on the material surface. Column study results indicate that the wood ash decreased iron concentrations for more than 100 days below 10 mg L-1 (99 % iron removal), mainly due to iron Electronic supplementary material The online version of this article (doi:10.1007/s10230-012-0199-z) contains supplementary material, which is available to authorized users. T. Genty (&) B. Bussie`re Department of Applied Sciences, UQAT, Rouyn-Noranda, QC J9X 5E4, Canada e-mail: [email protected] T. Genty B. Bussie`re M. Benzaazoua G. J. Zagury Industrial NSERC-Polytechnique-UQAT Chair, Environment and Mine Waste Mgmt, Rouyn-Noranda, QC J9X 5E4, Canada M. Benzaazoua Laboratoire de Ge´nie Civil et d’Inge´nierie Environnementale, INSA de Lyon, 69621 Villeurbanne Cedex, France G. J. Zagury Department of Civil, Geological, and Mining Engineering, E´cole Polytechnique de Montre´al, Montreal, QC H3C 3A7, Canada
hydroxide precipitation and sorption. The risk of system clogging was negligible since the saturated hydraulic conductivity remained stable, between 5.0 9 10-3 and 3.1 9 10-2 cm s-1. Between 44 and 52 % of the sulphate was also removed due to gypsum precipitation. Keywords Column tests Sorption Passive treatment Reuse of by-product
Introduction Wastes produced during mining operations can significantly contaminate drainage water (Aubertin et al. 2002; Blowes and Ptacek 1994; Evangelou and Zhang 1995; Kleinmann et al. 1981). Several methods exist to treat acid mine drainage (AMD) and attain regulatory criteria; active lime treatment is the most commonly used. At closed mine sites, passive treatment systems are preferred because they use natural or waste materials and have low operating and maintenance costs (Johnson and Hallberg 2005; Neculita et al. 2007; Skousen and Ziemkiewicz 2005). Passive treatment systems, such as anoxic limestone drains (ALDs) and sulfate-reducing passive biofilters (SRPBs), have demonstrated their effectiveness, at least in the short term, for slightly or moderately-cont
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