Solar photocatalytic treatment of landfill leachate using a solid mineral by-product as a catalyst

Abstract

The treatment of municipal solid waste landfill leachate in a pilot plant made up of solar compound parabolic collectors, using a solid industrial titanium by-product (WTiO2) containing TiO2 and Fe(III) as a photocatalyst, was investigated. In the study evidence was found showing that the degradation performed with WTiO2 was mainly due to the Fe provided by this by-product, instead of TiO2. However, although TiO2 had very little effect by itself, a synergistic effect was observed between Fe and TiO2. The application of WTiO2, which produced coupled photo-Fenton and heterogeneous catalysis reactions, achieved a surprisingly high depuration level (86% of COD removal), higher than that reached by photo-Fenton using commercial FeSO4 (43%) in the same conditions. After the oxidation process the biodegradability and toxicity of the landfill leachate were studied. The results showed that the leachate biodegradability was substantially increased, at least in the first stages of the process, and again that WTiO2 was more efficient than FeSO4 in terms of increasing biodegradability.