Effect of different wastewater composition on kinetics, capacities, and mechanisms of phosphorus sorption by carbonated bauxite residue

This study aims at evaluating the effect of different wastewater composition on kinetics, capacities, and mechanisms P sorption by carbonated bauxite residues (CBR). A series batch experiments was performed to investigate behaviors from solutions prepared with aqueous matrices (deionized water, tap real wastewater) initial concentrations (from 10 200 mg P/L). Also, a sequential extractions fractionation CBR before after its use in experiments, hence elucidate main removal mechanisms. The results indicate that concentration is most influential parameter controlling experiments. Kinetic constant increases exponentially decreasing below 100 P/L, thus indicating faster achievement equilibrium. Equilibrium capacities increase linearly about 0.2 3.9 P/g increasing saturation not reached. Ca phosphate precipitation mechanism higher (> P/L), whereas adsorption surface becomes more relevant over total amount removed lower concentrations. Overall, findings this allow evaluate kinetic constants, under operating scenarios, providing crucial information for design operation treatment units.