Photo-Fenton process as an efficient alternative to the treatment of landfill leachates

Advanced oxidation processes (AOPs), namely photo-Fenton, Fenton-like, Fenton and UV/H2O2, have been investigated in the removal of organic matter and colour from landfill leachates. The leachate was characterised by high COD, low biodegradability and intense dark colour. Evaluation of COD removal as a function of the operation variables (H2O2, Fe2+, Cu2+, UV) led to results that ranged between 30% and 77% and it was observed that the removal efficiencies decreased in the order: photo-Fenton > Fenton-like > Fenton > UV/H2O2 > UV. Thus, a detailed experimental analysis was carried out to analyse the effect of the hydrogen peroxide and iron concentrations and the number of reagent additions in the photo-Fenton process, observing that: (i) the COD removal ranged from 49% to 78% depending on the H2O2 dose, (ii) the total amount of organic matter removed was increased by adding the reagent in multiple steps (86%), (iii) iron concentration corresponding to a Fe2+/COD mass ratio = 0.33 was found to be the most favourable and, (iv) after a neutralization step, the colour and residual concentrations of iron and H2O2 were practically negligible in the final leachate solution. (c) 2007 Elsevier B.V. All rights reserved.