The treatment strategy of landfill leachate is not easy to define in general terms due to differences. involving its composition, dumping place, and age of wastes. Since it is of specific type, characterized by high loading caused by refractive compounds, organic and inorganic substances, they are much more difficult to treat in comparison with municipal sewage. For this reason, the application of hybrid processes is advantageous, because, they enable the treatment of all contaminants present in the leachate. Preliminary tests of sanitary landfill leachate were carried out, using the following hybrid systems: activated sludge-chemical oxidation, activated sludge-ultrafiltration-chemical oxidation and activated sludge-ultrafiltration-reverse osmosis. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.