Iron removal and pH stabilization of synthetic acid mine drainage (AMD) using peat soil and limestone.

Abstract A Successive Alkalinity Producing System (SAPS) was evaluated for the remediation of synthetic Acid Mine Drainage (AMD) by using an organic substrate of peat soil and limestone aggregate. The characterization of the AMD was conducted by the testing the AMD effluent originated from active mining site at Pengkalan Hulu, Perak, Malaysia. The characterization of the peat soil and limestone revealed stipulated composition, carbon content in the peat soil and particle size distribution of the limestone. Synthetic AMD was prepared incorporating iron sulphate (FeSO4) and sulphuric acid (H2SO4). The synthetic AMD was acidic (pH < 4.0) and with 50, 75 and 100 ppm Iron (Fe) concentration. A laboratory scale physical model to simulate a tailing pond was developed. The synthetic AMD was introduced and passed through the filtration media. Subsequently, water samples were collected and analyzed to determine pH level. Additionally, the Fe concentration was analyzed using UV-Vis test at 6 to maximum 48 hours’ retention time. The residues of the peat soil and limestone from the physical model were further analyzed using SEM-EDX microscopic to determine the remaining iron content absorb or precipitate onto the peat soil and limestone. The analysis revealed that the innovative methodology has successfully reduced more than 85 % iron content and neutralized the pH only after 6 hours of retention time. These results proved the combination of peat soil and limestone potentially can be proposed as the alternate solution for treating the AMD effluent from the mining site.