Journal article
Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions
Journal of Cleaner Production, Vol.187, pp.699-707
2018
Abstract
Accumulation of organic impurities (specifically oxalate) in Bayer liquor is a significant constrain to refine alumina. Microbial oxidation is a low-cost approach to remove organics, but hostile conditions of Bayer liquor (pH > 14 and nitrogen (N) deficiency) makes it challenging. The solution remains with selection of an appropriate haloalkaliphilic culture and alumina refineries currently have access to two types of bacterial cultures (N-supplemented and N-deficient cultures). To date there is no comparative assessment of the two cultures to examine which one is more suitable to reduce operational risks (i.e. with higher removal efficiencies over a broader range of pH) and costs.
Hence, this study compared oxalate removal efficiencies of two packed bed biofilm reactors (N- supplemented and N-deficient) on exposure to a range of influent pH and simple organic compounds. Both reactors were operated (>265 days) at pH 9 and pH influence was compared in batch experiments. Results suggested that both biofilms could tolerate a broad pH range (7-10). The optimal specific oxalate removal rate of N-supplemented reactor was restricted to pH 9, whereas the maximal rate was maintained over a wider pH range (7 - 8) in N-deficient reactor. In this range, the N-deficient system outperformed the N-supplemented system (105 vs. 130 mg-oxalate /h.g-biomass). Although acclimatized primarily with oxalate, both biofilms simultaneously oxidized other organics (acetate, formate, malonate and succinate) without a noticeable influence on oxalate removal. This study suggests that N-deficient systems are more versatile and better suited to remove organic impurities in Bayer liquor.
Details
- Title
- Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions
- Authors/Creators
- T.N. Weerasinghe Mohottige (Author/Creator)K.Y. Cheng (Author/Creator)A.H. Kaksonen (Author/Creator)R. Sarukkalige (Author/Creator)M.P. Ginige (Author/Creator)
- Publication Details
- Journal of Cleaner Production, Vol.187, pp.699-707
- Publisher
- Elsevier Limited
- Identifiers
- 991005544356207891
- Copyright
- © 2018 Elsevier Ltd.
- Murdoch Affiliation
- School of Engineering and Information Technology
- Language
- English
- Resource Type
- Journal article
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