Aspects regarding the pollution of natural resources with heavy metals

The natural resources of water (surface and groundwater) are frequently polluted because of the spreading in aqueous media of the different organic and inorganic pollutants. Among inorganic pollutants often present in water at concentrations over the imposed limits are heavy metals ions (Fe, Mn, Zn, Cu, Cr, Pb and As) with toxic characteristics on aquatic ecosystems and human health. In the paper are presented data regarding to: variation domain for heavy metals ions and other pollutants in some sources of groundwater situated in different countries of Romania (Arad, Bihor, Bacau, Dambovita, Giurgiu, etc); identification of the pretreatment / treatment possibilities according with the specific pollution context. The main physico-chemical processes included in the treatment flows are: chemical oxidation, precipitation, coagulation-flocculation, settling, filtration and adsorption on different materials. The performed studies were finalized with the selection of the proper treatment schemes for advanced removal of heavy metals from natural sources in accordance with physico-chemical characteristics of the water sources, respectively the specific pollution context: type and concentration of metallic compounds; imposed limits for identified pollutants.