An Evaluation of Basic Oxygen Furnace Slag as Post-Treatment for Acid Rock Drainage

Oxic beds containing basic oxygen furnace slag were evaluated as potential post-treatment method for sulfate reducing bioreactor (SRB) treatment of acid rock drainage. SRB effluent was pumped into BOF slag/sand leach beds, also known as oxic slag beds (OSBs), at various flow rates. OSB influent versus effluent concentrations of dissolved metals (specifically magnesium and manganese) and water quality parameters (pH, dissolved oxygen concentration, and conductivity) were compared. The OSBs increased the pH of the SRB effluents from 6.2–6.7 to 7.5–8.3. Dissolved oxygen concentration increased from 2-4 mg L^(-1) to approximately 8 mg L^(-1). Conductivity remained similar, with some effluent values being less than influent. Manganese concentration was observed to be reduced through OSB post-treatment by an average of 8.2% reduction and a maximum of 23 % reduction. Magnesium was not reduced during OSB post-treatment. Other metal concentrations changes were analyzed. Recommendations the design of OSBs for future studies were made, and a proposed design was configured.