Quantitative Modeling for Continuous Treatment of Zinc Contained Acid Mine Drainage Using Column Filling Leaf Mold

The objective of this study is to clarify the zinc removal mechanism and construct a quantitative model for column experiments using a natural component of organic soils, namely leaf mold. We performed column experiments using actual acid mine drainage (AMD) at several conditions. After column experiments, the residues in the column were analyzed by x-ray absorption fine structure (XAFS) analysis. These experimental results highlighted that when leaf mold, limestone, and iron powder were filled in the column, the zinc removal mechanism was not only surface complexation for leaf mold but also the formation of zinc sulfide. Whereas, when only leaf mold was filled in the column, that was only surface complexation for leaf mold. Based on the above results, we constructed a quantitative model incorporating surface complexation by leaf mold, sulfate reduction reaction by sulfate-reducing bacteria, Fe2+ dissolved reaction from leaf mold, and one-dimensional transport against the height of the column. The experimental results of pH and the concentration of each element were successfully represented by the quantitative model.