Résumé:
In this work, the purified water and waste sludge of Sidi Merouane wastewater treatment plant located in Mila in the Northeast Algeria are characterized in the objective of their valorization in agriculture. The sludge is also used in the production of activated carbon for water water treatment application. The quality of Sidi Merouane treated waters is evaluated through physicochemical analysis. The obtained results show that they are characterized by alkaline pH, high electrical conductivity and low concentrations of nitrate and phosphate. The contents of the analyzed heavy metals are below the limits of water discharges. The mineralogical composition of waste sludge is evaluated by XRD and FTIR analysis. It reveals the presence of clay phases associated with organic matter. Their physicochemical characterization is carried out by measuring pH, electrical conductivity and by analysis of major elements, nutrients, organic matter and metals. The obtained results show the mineral character of the Sidi Merouane waste sludge. Nitrogen is predominantly in organic form; among its mineral species, ammonium predominates whatever the season. Phosphorus is predominantly inorganic and the fraction bound to oxyhydroxids is the most important. The calculated C/N ratio shows that nitrogen is not immobilized.in the waste sludge of the Sidi Merouane wastewater treatment plant. The concentrations of the analyzed heavy metals are below the limits allowed for valorization sludge in agricultural. Activated carbons are prepared from waste sludge of Sidi Merouane plant by calcination at 550 °C and by chemical activation using an acidic mixture (H2SO4 + H3PO4). They are characterized by FTIR and BET analysis and by the determination of pHpzc and iodine number. The effectiveness of the use of the prepared carbons in waste water treatment is evaluated through the adsorption of an organic pollutant (a dye) and an inorganic pollutant (metal ion). A commercial activated carbon is also used for a comparison. The obtained results show that the activated carbon prepared by chemical activation is characterized by a high specific surface area (1114 m2/g), an important iodine number (1435) and an acidic pHpzc (3.6). Its adsorption capacities for Black Eriochrome T and chromium (III) ions are 370mg/g and 32mg/g respectively. These capacities are higher than those of the commercial activated carbon used.
