Limited reserves of fresh water are a serious global problem. For that reason the main objective is to preserve the quality of all available sources of drinking water. Among all the threats to water in nature, leachate landfills are most dangerous because of their complex chemical composition and continuous uncontrolled pollution of groundwater. Processes and methods of preventing the spread of pollution into groundwater and leachate treatment are a challenge for many researchers. This proposal should be a contribution to the landfill leachate treatment using natural zeolite as a reactive barrier. This material is available in nature, environmentally compatible, thermally and chemically stable, and possesses adsorption and ion exchange properties. Depending of the surface charge, zeolites can uptake organic and inorganic positive and negative species. The desired surface charge can be achieved by chemical modification using different methods at a controlled pH value. Modified zeolites should have significantly higher removal capacities and selectivity towards pollutants contained in the landfill leachate. These wastewaters are highly concentrated, have the most complex possible composition, contain low biodegradable organic matter (halogenated hydrocarbons, aromatic hydrocarbons and phenols), inorganic ions (Cl-, NH4+, SO42-,NO3-, NO2-,PO43-), and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, Mn). Many of these components have shown excellent removal from modal solutions onto zeolite; therefore investigations will start with batch studies, continue in lab-scale fixed bed columns, and finally in scale-up and multi stage columns filled with different modified zeolites. The multi stage column performance should be carried out with real leachate collected from the regulated landfills in the Dalmatian region. The exhausted zeolite, saturated with organic and inorganic pollutants, can be thermally treated and disposed of in nature, or solidified into the cement matrix.
