Traitement de la pollution phosphorée des effluents résiduaires urbains par des matériaux de Côte d’Ivoire constitués de schiste ardoisier, grès et latérite : approches en réacteur homogène, en mode hydrodynamique contrôlé et en réacteur micro-pilote de terrain

Abstract : This thesis is devoted to the study of phosphate ions adsorption processes by natural minerals of Ivory Coast, i.e. shale, sandstone and laterite mainly. Phosphate sorption by shale was first investigated in batch and column experiments. Batch experiments allowed the assessment of the influence of initial phosphate concentration, sorbent dosage, contact time, and pH on phosphate removal. The phosphate removal efficiency increased with increasing shale dosage while phosphate uptake decreased. Phosphate uptake strongly depended on pH, decreasing first with increasing pH in the range of 2-11 and then increasing at the highest pH value of 12. A correlation between aqueous Ca, Mg, Al, and Fe concentrations and phosphate uptake was observed. The kinetics was well described using the pseudo-second order model and isotherms with Langmuir sorption model. Column experiments with a flow rate of 1 ml min-1 and 25 mg L-1 initial phosphate concentration showed a breakthrough point at V/Vp of ~17 corresponding to a phosphate uptake of 0.2 mg g-1 in agreement with batch experiments. The performance of shale was evaluated as filter material in (Vertical Flow Constructed Wetland) VFCW in removal of phosphate ions, nitrogen, suspended solids, and organic compounds, using municipal wastewater. The influence of both shale granulometry and plants density was evaluated. The shale with the finest particle size offers a slightly higher efficiency. The flow rate decreased after wastewater treatment and the fooling is less pronounced for planted VFCW. The filter with the highest plant density offers only slightly higher efficiency towards phosphate and nitrate removal. The phosphate sorption capacity of the plants is negligible confirming the importance in the choice of the filter medium. Finally, phosphate removal by shale was compared to sandstone and laterite in both batch and column experiments. The different chemical compositions of the materials influence strongly the reactivity towards phosphate ions. It is supposed that the status of iron in the material, i.e. in substitution in clays in shale and occurring as hematite and goethite in laterite and sandstone, explained the differences of reactivity. Both batch and column experiments revealed that phosphate uptake decreased in the following ranking order laterite > sandstone > shale. These three materials appear as promising filter materials in VFCW
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Theses
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http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2018_0133_KPANNIEU.pdf
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Submitted on : Tuesday, November 13, 2018 - 4:27:20 PM
Last modification on : Wednesday, November 14, 2018 - 1:18:56 AM

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Dan Eude Kpannieu. Traitement de la pollution phosphorée des effluents résiduaires urbains par des matériaux de Côte d’Ivoire constitués de schiste ardoisier, grès et latérite : approches en réacteur homogène, en mode hydrodynamique contrôlé et en réacteur micro-pilote de terrain. Chimie analytique. Université de Lorraine; Université Nangui Abrogoua (Abidjan), 2018. Français. ⟨NNT : 2018LORR0133⟩. ⟨tel-01921180⟩

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