A combined passive system for the mitigation of acid mine drainage
The mitigation of AMD at Canadian mine sites using passive treatment technologies requires a combined strategy which aims at minimizing the impact of climatic variability on the treatment performance of the system. A vertical-flow combined passive treatment system was developed for the mitigation of AMD. Laboratory investigations were undertaken to characterize AMD mitigation through the peat biofilter and evaluate the performance of the combined passive system. Peat column sorption studies conducted at 20°C and 0°C demonstrated the impact temperature on metal retention. At 0°C, a metal breakthrough order of Cd < Mn < Zn < Al < Ni < Cu < Fe was noted. At 20°C, however, sulphate-reducing conditions were developed in the column leading to a significant increase in effluent pH and metal removal. Sequential extraction indicated that Fe, Cu and Al were typically bound to the organic matter fraction, while Mn, Zn, Ni and Cd were primarily associated with the exchangeable fraction. A bench-scale combined passive treatment system dosed with moderate strength synthetic AMD at a surface loading of 95 L/m 2/d, was operated under continuous flow conditions. Removal efficiencies for Fe, Al, Zn, Mn, Ni, Cu of 99.7%, 99.9%, 99.9%, 98.6% 98.2% and 99.9% were observed, respectively, while Cd remained fairly mobile through the system. Sulphate concentrations were reduced to 814.9 mg/L and the highly acidic drainage was neutralized with an effluent pH of 7.2 and an alkalinity of 1353.6 mg/L as CaCO 3. Therefore, the bench-scale combined passive treatment system was successful in mitigating moderate strength AMD.
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|Joint 2002 CSCE/ASCE International Conference on Environmetal Engineering - An International Perspective on Enviromental Engineering|
|Organisation||Department of Civil and Environmental Engineering|
Champagne, P., van Geel, P, & Parker, W. (2002). A combined passive system for the mitigation of acid mine drainage. Presented at the Joint 2002 CSCE/ASCE International Conference on Environmetal Engineering - An International Perspective on Enviromental Engineering.