Comparative MCDM Analysis for AMD Treatment Method Selection

Robule Lake, located in Eastern Serbia, near the city of Bor, is being influenced by waste materials from mining activities. For the purification of water from Robule Lake, contaminated with various metal ions (Fe, Cu, Zn, Mn, Cd, Ni, etc.), acid mine drainage (AMD) treatment methods such as: passive treatment method, sequential neutralization, ion exchange, adsorption process based on low cost adsorbents, adsorption process based on natural zeolits, electrodialysis, filtration with nanofiltration membranes, and reverse osmosis, were evaluated by the following MCDM methods: TOPSIS, VIKOR, MOOSRA, WASPAS, and CoCoSo. Criteria used for the evaluation were: efficiency in the metal ions removal and the quality of the purified water, necessity of pre-treatment and / or post-treatment of treated water, possibility of using the generated waste, capital costs, operating and maintenance costs, needed area, and sensitivity of the method. The results of the MCDM analysis showed that sequential neutralization was the most appropriate method for this wastewater, while passive treatment system and ion exchange were ranked as second and third, respectively. After the selection of AMD treatment method, neutralization tests with lime were carried out with the water sample from Robule Lake. The results of sequential neutralization testing showed that concentration of Fe ions could be lowered to 1 mg/L at pH 4. The values of Cu, Zn, and Ni ions concentration obtained at pH 7 were 0.04, 0.65, and 0.21 mg/L, respectively, while the values of Mn and Cd ions concentration of 0.01 and 0.0001 mg/L, were obtained at pH 10.