Treating Waste\nwith Waste: Activated Bauxite Residue\n(ABR) as a Potential Wastewater Treatment

Bauxite residue (or\nred mud) is a highly alkaline waste\ngenerated\nduring the extraction of alumina. As a result of the substantial accumulation\nof bauxite residue in tailings facilities, there is a growing interest\nin exploring the potential for reusing this material for other purposes.\nThe main objective of this study is to evaluate the use of activated\nbauxite residue (ABR) for remediating oil sands process-affected water\n(OSPW) and as a supplement to municipal wastewater treatment through\nbench-scale, proof-of-concept studies. The ABR is produced through\na reduction roasting process that alters the physicochemical properties\nof bauxite residue, resulting in the generation of potentially effective\nadsorbent media. The treatment performance via chemical and biological\nactivity removals (cytotoxicity, estrogenicity, and mutagenicity)\nwas also assessed. For OSPW, ABR treatment resulted in the effective\nremoval of recalcitrant acid-extractable organics (AEOs), with kinetics\nfollowing the pseudo-second-order and comparable adsorption capacity\nto other waste materials (e.g., petroleum coke). ABR also effectively\nreduced the estrogenicity and mutagenicity of OSPW, albeit cytotoxicity\nincreased at higher dosages, possibly due to some components leaching\nout of the material (e.g., metals). For municipal wastewater, ABR\ntreatment reduced fecal coliform concentrations (>99%), total phosphorus\n(up to 98%), total ammonia-nitrogen (63%), estrogenicity (nondetectable),\nand mutagenicity (nondetectable), especially in the primary effluent.\nThe ultimate end use of ABR is for the recovery of valuable metals\n(especially iron) and as a construction material, but additional work\nis needed to optimize the dosage (currently in the g/L range) and\nmaximize the use of ABR as an adsorbent prior to its subsequent uses.