PHOSPHATE REMOVAL FROM WASTEWATER BY CALCITE AND DOLOMITE ORES

Abstract

The objective of this work is to study the feasibility of two raw materials, calcite and dolomite, as adsorbent for phosphate removal from wastewater. The natural ores were characterized by using both chemical analysis and x-ray diffraction. The results indicate that the calcite sample having the chemical formula CaCO 3 (99 %Ca) and the dolomite is CaAlFeCO 3 (30 %Ca). The effects of pH, contact time and phosphate concentrations on the efficiency of removing were studied. The results indicate that the optimum conditions are : pH = 12, time of contact = 15 min, and the adsorption capacity increased as the phosphate content in the initial solution increased due to the increase of diffusion of the phosphate species. The calcite samples have a higher efficiency than that for dolomite, this may attributed to the higher content of Ca 2+ which acts the more active sites. The mechanism of removing was suggested according to the presence of cations derived from the adsorbent surface and anions loaded on the aqueous medium.