Résumé
The aim of this work is to evaluate an effective filtration technique for residual organic pollutants and heavy metals removal using two types of sand rich in iron oxide as a massive filter (sieved and gross sand). X-ray diffraction, X-ray fluorescence (XRF), scanning electron microscopy, energy dispersive spectroscopy (EDS) and specific surface area BET were investigated to characterize the sand. Experimental results showed that the BOD5 removal was found to be 93% for gross sand (GS) and 96% for sieved sand (SS). The COD removal was equal to 98.9 and 99.7% for GS and SS, respectively. The hydrogen bonding, complexation/precipitation process, ions exchanges and electrostatic interactions are the main phenomena proposed to describe residual organic pollutants removal. For heavy metals adsorption, results show a great efficiency removal between 90 and 100% for both cases. The adsorption mechanism was proposed based on zero-point charge, FTIR analysis, fluorescence (XRF) and EDS. The fixation of heavy metals onto the sand could be referred to hydrogen bonding, electrostatic interaction, ion exchange and electron donor-acceptors.
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