Treating waste with waste: utilizing calcined bauxite residue (CBR) as a potential wastewater treatment option
Bauxite residue is a byproduct generated during the extraction of alumina from bauxite ore. It is highly alkaline and has the potential to release toxic substances (metals) into the surrounding environment during storage. Hence, there is a growing interest in exploring the potential for metal recovery and/or repurposing of bauxite residue to reduce the substantial accumulation of tailings, subsequently contributing to more sustainable waste management practices. This study examined the efficacy of calcined bauxite residue (CBR) as a sorbent material during wastewater treatment. Four types of wastewaters were examined, but this thesis ultimately focused on oil sands process-affected water (OSPW) and municipal wastewater treatment plant (WWTP) effluents. This project is funded by MITACS Accelerate with GRON Holding Corporation as our industry partner.
The applicability of CBR in the treatment of industrial wastewater polluted with organic dye (e.g., textile wastewater) and natural waters that receive treated effluents was also evaluated. The treatment performance of CBR was evaluated using a combination of analyses including (1) physical via characterization of CBR via imaging, elemental and crystallographic composition, and surface area/pore size distribution ; (2) chemical via measurement of specific pollutant removal including methylene blue, acid-extractable organics (AEOs), metals, and other general water quality parameters; (3) biological via evaluation of toxicity (cytotoxicity, estrogenicity, and mutagenicity) via in vitro bioassays and measurement of total coliform bacteria. Post-treatment neutralization with acetic acid was further implemented as the pH and the concentration of dissolved metals in water, especially aluminum (Al), increased significantly after CBR treatment.