The rapid increase in industrial activities during the last decades has caused severe changes in the environment. This development has led to contamination of water resources with toxic contaminants such as heavy metals nutrient ions and dyes. Mining, mineral processing, and metallurgical operations (electroplating units, alloy manufacturing, etc.) generate a considerable amount of polluted water containing toxic heavy metals, which are almost persistent and non-degradable in nature, and which in turn cause adverse effects in the environment. Therefore, the treatment of these wastewaters becomes necessary before being discharged into the environment and river water streams, respectively. Several conventional methods (e.g., chemical precipitation, coagulation, sedimentation, adsorption, reduction, oxidation, solvent extraction, electrolytic extraction, evaporation, ion exchange, dialysis/electrodialysis, membrane processes, etc.) have been used to achieve effective and rapid removal of these environmental contaminants -particularly metal ions because of their toxic nature and high production cost, and limited or decreasing availability of metal deposits [1][2].However, some of these techniques have constrains on their application, such as the high operating cost, energy-intensive use hazardous chemicals, and Pol. J. Environ. Stud. Vol. 28, No. 1 (2019), 337-341 AbstractThe objective of this paper was to investigate the applicability of using biowaste materials prior to reverse osmosis treatment of water and wastewater effluents. The physico chemical properties of wheat bran, maize cob, and olive waste, and adsorption parameters such as metal concentration, adsorbent dose, contact time, and temperature of Cd(II) onto wheat bran are presented. The optimal parameters achieved in these experiment were used for sorptive removal of metal ions (Pb ) from synthetic aqueous solution as well as from wastewater effluents of the mining flotation process. At short pretreatment time, retentate of sufficient concentration was achieved with above biosorbents for further treatment. It is used as feed for reverse osmosis tests. The high removal efficiency of metal ions from synthetic as well as wastewater samples was obtained with low-pressure heterogeneous asymmetric reverse osmosis membranes almost completely by this process.

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Kosovo ore deposits are located in the Trepça belt which extends for over 80 km. The concentrate produced by the fl otation process of the Trepça metallurgical corporation contains a considerable quantity of valuable metals, such as Pb, Zn, Fe and minor accompanying metals such as Cd, Cu, As, Sb, Bi, Ag, Au, etc. The subject of this work was to assess the concentration of major and minor metals in lead and zinc concentrates of Trepça and to study the correlation coeffi cients between metals. Chemical determination of concentrates was performed by using atomic absorption spectroscopy (AAS). In the content on lead concentrate samples, the following were found: Pb>Fe>Zn> Ag> As>Sb>Cd. In the content of zinc concentrate, the following were found: Zn>Fe>Pb>Ag>As>Cd. The program "Statistica ver. 6.0" has been used for calculations of basic statistical parameters, relationships between data and cluster analysis of R-mode. R-mode cluster analysis on lead concentrate samples showed that Pb has the closest linkages with Fe and they form one branch of the dendogram. On the zinc concentrate samples, Zn has the closest linkages with Fe and they form one branch of the dendogram.

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