Use of advanced oxidation processes to improve the biodegradability of mature landfill leachates

Two advanced oxidative processes (Fe 2+/H 2O 2/UV and H 2O 2/UV systems) were used for the pre-treatment of mature landfill leachate with the objective of improving its overall biodegradability, evaluated in terms of BOD 5/COD ratio, up to a value compatible with biological treatment. At optimized experimental conditions (2000 mg L −1 of H 2O 2 and 10 mg L −1 of Fe 2+ for the photo-Fenton system, and 3000 mg L −1 of H 2O 2 for the H 2O 2/UV system), both methods showed suitability for partial removal of chemical oxygen demand (COD), total organic carbon (TOC) and color. The biodegradability was significantly improved (BOD 5/COD from 0.13 to 0.37 or 0.42) which allowed an almost total removal of COD and color by a sequential activated sludge process. In addition, gel permeation chromatography (GPC) has showed a substantial agreement on the cleavage of large organic compound into smaller ones.