## 1 Introduction  
Natural resources such as coal, iron, nonferrous metals, precious metals, industrial minerals, etc., are of integral importance for the development of human societies. During the World Summit on Sustainable Development (Johannesburg, South Africa, 2002), it was decided that a concept of sustainable development would be based on the environmental protection as one of the three main pillars, both for the developed and developing countries. Mining and mineral processing on the Balkan Peninsula, including Albania, Bosnia and Herzegovina, North Macedonia, Kosovo (Territory under the Interim UN Administration), Montenegro, and Serbia, has played a vital role in the European history and economy. Actually, this area was a major part of the supplies of copper, lead, and zinc in Europe until 1990 [1]. The global mining activities (mineral and metal production processes) produce several billion tons of solid inorganic wastes or by-products, including the liquid waste [2]. According to the study made for the Environment Directorate-General, European Commission, more than 4.7 billion tons of mining waste and 1.2 billion tons of tailings waste are stored all over the European Union [3]. The open pit or underground mining operations generally have a serious negative impact on the surrounding environment, such as the air pollution, land use and biodiversity, and water availability. Noise and vibrations, the use of energy sources, and visual effects are sometimes negative consequences of the mining and metallurgical activities. In addition to the active sites, thousands of the \"old\" or \"depleted\" sites are scattered in the region. Furthermore, some effluents generated in the metal mining industry contain large quantities of toxic substances (cyanides, heavy metals, and other harmful and dangerous substances), which have serious human health and ecological implications [4; 5; 6]. Mine water generated from the active as well as the abandoned mines is one of the main chemical threats to the groundwater and surface water quality. Mine waters are, as a rule, acidic with pH value mostly between 2.5 and 4 due to an elevated concentration of sulfuric acid, as the second product of bacterial oxidation of sulfide minerals. Pyrite is the most abundant mineral in the poly-metallic sulfide ore deposits and mining waste dumps. The oxidation of pyrite and copper minerals in an aqueous environment occurring via two simultaneous mechanisms, i.e., biochemical involving bacteria, and chemical way, can be described by the following stoichiometric reactions [7; 8; 9]:  
\[\left(\text{bacterial}\right)\ 2 FeS_{2}\ +\ 7.5O_{2}\ +\ H_{2}O\to Fe_{2}(SO_{4})_{3}\ +\ H_{2}SO_{4} \tag{1}\]  
\[\left(\text{chemical}\right)\ 2 FeS_{2}\ +\ 7 Fe_{2}(SO_{4})_{3}\ +\ 8H_{2}O\to 15 FeSO_{4}\ +\ 8H_{2}SO_{4} \tag{2}\]  
\[\left(\text{chemical}\right)\ \ FeS_{2}\ +\ Fe_{2}(SO_{4})_{3}\to 3 FeSO_{4}\ +\ 2S^{0} \tag{3}\]  
\[\left(\text{bacterial}\right)\ \ S^{0}\ +\ H_{2}O\ +\ 1.5O_{2}\to H_{2}SO_{4} \tag{4}\]  
Generation and release of acid mine drainage (AMD) containing elevated concentrations of metals from the mine waste induces an environmental problem on a global scale, and some kind of method, active or passive treatment, is required for the mine drainage [10]. The active treatment methods use neutralizing agents to raise the pH up to the effluent water quality standards [11; 12; 13; 14; 15]. Mine water originating from the active or closed copper mines contains copper ions sometimes in a considerable concentration usually associated with an equivalent or even two times higher concentration of Fe\({}^{2+}\)/Fe\({}^{3+}\) ions as a consequence of bacterial leaching the sulfide copper and iron minerals. The presence of other heavy metal ions (Mn, Cd, Zn, Pb, Ni, etc.) in the mine water depends on mineralization of an ore body, but their concentration is much lower than the concentration of copper or iron.