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Journal article
New perspectives for bio-technical treatment of oxalate-containing waste streams from bauxite processing
Hydrometallurgy, Vol.220, 106105
2023
Abstract
Alumina is typically produced from bauxite ore using the Bayer process, in which the ore is mixed with alkaline liquor under elevated temperatures. Australian bauxite ore contains a wide range of organics, which detrimentally affect the Bayer process. Therefore, the removal of organic compounds from the alkaline Bayer process liquor is critical in maintaining process efficiency and alumina quality. Oxalate (C2O42−) is a key organic impurity in the Bayer process liquors that requires removal as it increases in concentration in the processing circuit as the Bayer liquor is continually recycled. Compared to conventional physiochemical or physical methods (e.g., chemical precipitation, wet-oxidation, liquor burning), microbial bioreactor treatment processes have the potential to be more economical and environmentally sustainable for oxalate removal. Some Australian alumina refineries have implemented full-scale bioreactors such as moving bed biofilm reactors (MBBRs) and aerobic suspended growth bioreactors (ASGB). While these bioreactors are robust and effective in removing oxalate, they have some limitations, such as the need for pre-acidification of influent and the loss of ammonia (nutrient) through volatilization. Therefore, this study aimed to provide an overview of the fundamentals and recent advances in biotechnical processes for the treatment of alkaline oxalate-containing liquor. Laboratory-scale studies on promising new biotreatment concepts, such as the use of bioelectrochemical systems to facilitate concurrent oxalate degradation and caustics recovery, as well as the utilization of nitrogen-fixing microorganisms to obviate the requirement for external nutrient dosage, are discussed. Perspectives for further research on oxalate-containing waste streams are also proposed.
•Oxalate and other organics accumulate in highly alkaline and saline Bayer liquors.•Biodegradation shows promise for destructing problematic organics.•Various bioreactors, microbes and pathways can be used for oxalate degradation.•Bioelectrochemical systems (BES) enable organics destruction and caustic recovery.•BES reduce ammonia losses and emissions compared to aerobic bioreactors.
Details
- Title
- New perspectives for bio-technical treatment of oxalate-containing waste streams from bauxite processing
- Authors/Creators
- Ka Yu Cheng - CSIRO Land and WaterTharanga Weerasinghe Mohottige - Western Sydney UniversityManeesha P. Ginige - Commonwealth Scientific and Industrial Research OrganisationAnna H. Kaksonen - Commonwealth Scientific and Industrial Research Organisation
- Publication Details
- Hydrometallurgy, Vol.220, 106105
- Publisher
- Elsevier B.V
- Identifiers
- 991005593763107891
- Copyright
- © 2023 The Authors.
- Murdoch Affiliation
- School of Engineering and Energy
- Language
- English
- Resource Type
- Journal article
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