Process parameters study and organic evolution of old landfill leachate treatment using photo-Fenton-like systems: Cu2+ vs Fe2+ as catalysts

摘要

Landfill leachate generally contains many toxic and bio-resistant organic pollutants. Fenton oxidation technology is an ideal technique for the pre-treatment of wastewater containing harmful organic contaminants and biodegradability improvement. In this study, the response surface methodology (RSM) was used to optimize the reaction conditions of photo-Fenton-like systems, the catalytic performance of Fe2+/Cu2+ and mechanisms of catalytic process were comparatively investigated. In addition, the effects of reaction conditions on organic composition of landfill leachate under photo-Fenton-like systems were investigated by using 3-dimension excitation-emission matrix (3D-EEM), high performance size-expulsion chromatography (HP-SEC) and gas chromatography-mass spectrometer (GC-MS). The results showed that photo-Fenton-like systems had great performance in organic mineralization, the maximum DOC removal efficiencies were reached at 65.23% and 74.21% during the UV/Cu2+/H2O2 process and photo-Fenton process at the optimal reaction conditions, respectively. The photo-Fenton-like systems performed well in removing refractory organic matter such as fulvic acid (FA) and humic acid (HA), and it can also significantly improve the biodegradability of landfill leachate. Moreover, the Cu2+ could be completely recovered after oxidation treatment process, while Fe2+ was difficult to be regenerated due to formation of acid-insoluble ferric-hydroxy complexes.