Biochar for Treating Acid Mine Drainage

The goal of this study is to evaluate the capacity of poultry litter-derived biochar to treat acid mine drainage (AMD) from the Ilkwang mine, an abandoned Cu mine in South Korea, using batch and column experiments. We hypothesize that the biochar can act as a possible neutralizer and sorbent to remove toxic constituents from AMD. The AMD from Ilkwang mine is strongly acidic (pH 2.4 [spring]/2.5 [summer]) and contains high concentrations of Fe (119.1/302.8 mg/L), Al (40.6/51.3 mg/L), Mn (9.2/12.1mg/L), Cu (12.9/30.7mg/L), Zn (15.5/26.8mg/L), As (0.2/0.4mg/L), and SO42- (1087.3/1464.8mg/L). Concentrations of dissolved constituents were decreased in the presence of the biochar due to neutralization by imbedded carbonate minerals and sorption to the biochar surface, showing complete removal of Fe, Al, Cu, and As, and 99%, 61%, and 31% removal of Zn, Mn, and SO42-, respectively. In column experiments, increasing the biochar-to-AMD ratio significantly increased the removal of dissolved constituents from the AMD. Results suggest that poultry litter-derived biochar can remove toxic constituents from AMD to improve the quality of AMD before it enters the natural environment.