Comparison of the removal of 21 micropollutants at actual concentration from river water using photocatalysis and photo-Fenton

Abstract

The development of technologies capable of eliminating a wide spectrum of micropollutants of diverse nature from waters becomes essential. Advanced oxidation processes (AOPs) seem to be the most promising technologies but the most appropriate AOP to remove the micropollutants is still under debate. In this study, for the first time, the comparison of the efficiency of TiO2 heterogeneous photocatalysis and iron-impregnated faujasite heterogeneous photo-Fenton process is conducted towards the removal of a mixture of 21 micropollutants from a real river at low concentrations. The sampling area is situated on the Meurthe River, downstream the wastewater treatment plant of the city of Nancy in the northeast of France. To assess the impact of the micropollutants concentration and the matrix composition, two sampling campaigns have been performed at different periods of the year. Among the targeted micropollutants, 14 pharmaceuticals, 1 personal care product, 4 endocrine disruptors and 2 perfluorinated molecules are specifically followed. Their concentrations range from few ng L−1 to hundreds ng L−1. The adsorption of all the micropollutants is higher onto the iron-impregnated faujasite compared to that onto TiO2 due to the larger surface area of the iron-impregnated faujasite. The iron-impregnated faujasite offers superior photo-Fenton oxidation efficiency towards the degradation of the micropollutants over the TiO2 photocatalysis system. For almost all the micropollutants, the contaminants are totally removed after 30 min by photo-Fenton while a longer period is necessary by photocatalysis. A relationship between the removal efficiencies and the octanol–water partition coefficient (log Kow) of each micropollutant has been extracted from the data. A further economic evaluation confirms that the photo-Fenton process is also the better in terms of cost.