Étude expérimentale et théorique du procédé d'électrocoagulation : application au traitement de deux effluents textiles et d'un effluent simulé de tannerie

Abstract : Electrocoagulation (EC) is a water treatment technology that relies on the electrochemical sacrificial anodes (in Fe or Al) dissolution. This metal dissolve themselves in Al3+ and Fe2+ cations that later oxidise to Fe3+ ions. These cations form metal hydroxides that adsorb the impurities of the effluent while decreasing the zeta potential. The electrochemical reactor used consists on two plane parallel metal electrodes with recirculation of the effluent to be treated between them. Current densities from 50 to 200 A/m2 were imposed to treat each effluent. Three effluents were used in this study. The first one is an effluent sampled at the outlet of a textile plant (« plant »). The second one is a mixture of several effluents coming from different plant and collected at the inlet of the wastewater treatment (« treatment plant »). The last one is a wastewater tannery plant simulated by addition of 200 ppm Chromium VI in the treatment plant effluent. For each experience the current density and the time of treatment rule the electrical charge and the concentration in dissolved metal reached. The influence of these four parameters on the elimination of COD, absorbance, turbidity, COT and hexavalent chromium content has been studied. Parameters e.g. potential, faradic yield, metal dissolution and pH have also been continuously monitored to better understand their role on EC process. The results show that DCO abatement reached 80 and 82% for treatment plant effluent, respectively with iron and aluminium electrodes; and 75 and 67% for plant effluent, respectively with iron and aluminium electrodes. The chromium treatment yields 100 % abatement with Fe electrodes whereas it is only 70% using Al electrodes. Models have been developed for COD and absorbance removal for the two electrode materials. Model for chromium (VI) treatment has been established considering all reactions occurring for iron EC. Metal speciation study allowed us to determine the optimal pH of coagulation flocculation for each metal involved in the treatment (Al, Fe, Cr). Competition between organic pollution removal and chromium elimination has been also investigated for each electrode material
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Inoussa Zongo. Étude expérimentale et théorique du procédé d'électrocoagulation : application au traitement de deux effluents textiles et d'un effluent simulé de tannerie. Autre. Institut National Polytechnique de Lorraine, 2009. Français. ⟨NNT : 2009INPL066N⟩. ⟨tel-01748733⟩

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