BACKGROUNDLandfill leachate requires rigorous treatment to limit environmental impact. Often, granular activated carbon (GAC) filtration is part of the treatment train. Little is known on how a preceding (advanced) oxidation process (AOP) could modify the adsorption properties. As such, different AOPs were compared as preceding step to GAC filtration for treatment of biologically stabilized landfill leachate. RESULTSColumn tests showed that the GAC filters could be used substantially longer (>14 times compared with untreated leachate) after Fenton treatment. This is in contrast to leachate treated by UV/H2O2 (no improvement) and ozone. For UV/H2O2, most likely, the significant UV absorption of the leachate hindered the production of hydroxyl radicals. Ozonation (65% BOD increase), on the other hand, showed that there might be the potential to reduce costs related to external carbon source dosing by recycling part of the oxidized stream to the biological treatment unit. CONCLUSIONSThe lifetime increase was mostly due to higher removal of COD (up to 63%) as it was clearly indicated that the oxidation processes did not alter the adsorption properties to any great extent. A clear overview of the operational expenses indicated that using a coupled treatment (oxidation + GAC) could lead to a significant cost reduction. (c) 2014 Society of Chemical Industry