In-situ Coal Pit Lake Treatment of Acidity when Sulfate Concentrations are Low

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Journal Article

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Publication Details

Paper presented at the 7th International Conference on Acid Rock Drainage (ICARD), March 26-30, 2006, St. Louis MO. R.I. Barnhisel (ed.) Published by the American Society of Mining and Reclamation (ASMR), 3134 Montavesta Road, Lexington, KY 40502 Original article available here


Pit lakes (abandoned flooded mine pits) represent a potentially valuable resource to mining companies, the environment and community, if appropriate water quality can be achieved. However, the water is often of low pH with high dissolved metal concentrations. In Western Australia coal pit lakes are acidic (pH 3–5) but with low concentrations of sulfate and metals. Low sulfate concentrations prevent microbial sulfate reduction from reducing acidity in these lakes. However, stimulation of primary production and associated alkalinity generating processes may provide a cost effective and sustainable solution to the acidity problems. A field-scale experiment (with control) involving the treatment of in-situ macrocosms (~600 m3) in a small south-west, Western Australian coal mine lake with municipal mulch and phosphorus additions to enhance primary production was undertaken between June 2003 and June 2004. One macrocosm was treated with P additions, another with mulch, a third with mulch and P, and the untreated lake formed the control. Physico-chemical and algal (chlorophyll a) sampling of the macrocosms and lake occurred at monthly intervals.

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