Adsorbent properties of red mud and its use for wastewater treatment

With a view to simultaneously conserving the environment and an important natural resource, we assessed the feasibility of using red mud (RM), a residue from bauxite refining, for wastewater treatment. Moistened mixtures of RM and 8% (w/w) CaSO4 form aggregates which are stable in aqueous media. Batch experiments examining adsorption of phosphorus (P) by these aggregates for contact times of 3, 6, 24 and 48 h indicated that adsorption occurred by both fast and slow reactions. Likewise, comparison of experimental breakthrough curves (BTCs) for P retention on a column of RM aggregates (residence time 3 h) with MCMFIT-simulated BTCs indicated that fast and slow adsorption reactions were occurring. Actual P retention was predicted, taking into account both kinetics of fast and slow adsorption reactions. The RM aggregates had maximum adsorption capacities (evaluated from fits (0.90