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CHALLENGES OF PASSIVE TREATMENT OF METAL MINE DRAINAGE IN THE IBERIAN PYRITE BELT (SOUTHERN SPAIN): PRELIMINARY STUDIES
Citation:
ROTTING, T. S., R. C. THOMAS, C. AYORA, AND J. CARRERA. CHALLENGES OF PASSIVE TREATMENT OF METAL MINE DRAINAGE IN THE IBERIAN PYRITE BELT (SOUTHERN SPAIN): PRELIMINARY STUDIES. In Proceedings, 2006 7th ICARD, St. Louis, MO, March 26 - 30, 2006. American Society of Mining and Reclamation, Lexington, KY, 1753-1767, (2006).
Impact/Purpose:
Improve the scientific understanding of the processes controlling nutrient distributions in surface waters. Produce a suite of enhanced models for characterizing nutrient distributions in surface waters by incorporating improved process understanding in existing models (e.g., WASP), by developing new models (e.g., WHAM, reactive transport), and improving linkages between model components.
Description:
AMD in the Iberian Pyrite Belt is a problem of global scale. Successful implementation of passive treatment systems could remediate at least part of this problem at reasonable costs. However, initial trials with ALD and RAPS based on gravel size limestone failed due to rapid loss of chemical reactivity and plugging. Limestone buffered organic substrate (LBOS), which employs fine-grained limestone in an organic matrix, is an attractive alternative to conventional RAPS or ALD substrates, because it combines high reactivity with low plugging. However, LBOS has only been tested on ferric-iron waters, while our target AMD is mainly ferrous iron. Due to the high ferrous to ferric iron ratio, we envision a LBOS treatment system that relies on sulfate reducing bacteria (SRB) in addition to the fine-grained limestone in the substrate. This study presents preliminary batch and column trials on reactivity and hydraulic properties. Other challenges include finding appropriate and locally available LBOS components. Tested substrates include compost, wood chips, limestone screenings and sugar beet lime.
Results show that only some SRB types tolerate the high metal concentrations. Reactors with SRB activity produce higher alkalinity, but support lower flow rates than reactors based on limestone dissolution only.