Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions
Accumulation of organic impurities (specifically oxalate) in Bayer liquor is a significant problem for alumina refineries. Microbial degradation is a low-cost solution to the problem, but hostile conditions of Bayer liquor (pH > 14 and nitrogen (N) deficiency) makes it challenging. The soluti...
| Main Authors: | , , , , |
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| Format: | Journal Article |
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Elsevier
2018
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| Online Access: | http://hdl.handle.net/20.500.11937/69850 |
| _version_ | 1848762149617270784 |
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| author | Weerasinghe Mohottige, T. Cheng, K. Kaksonen, A. Sarukkalige, Priyantha Ranjan Ginige, M. |
| author_facet | Weerasinghe Mohottige, T. Cheng, K. Kaksonen, A. Sarukkalige, Priyantha Ranjan Ginige, M. |
| author_sort | Weerasinghe Mohottige, T. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Accumulation of organic impurities (specifically oxalate) in Bayer liquor is a significant problem for alumina refineries. Microbial degradation is a low-cost solution to the problem, 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 acclimatised primarily with oxalate, both biofilms simultaneously oxidised 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. |
| first_indexed | 2025-11-14T10:42:59Z |
| format | Journal Article |
| id | curtin-20.500.11937-69850 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:42:59Z |
| publishDate | 2018 |
| publisher | Elsevier |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-698502019-01-11T07:24:29Z Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions Weerasinghe Mohottige, T. Cheng, K. Kaksonen, A. Sarukkalige, Priyantha Ranjan Ginige, M. Accumulation of organic impurities (specifically oxalate) in Bayer liquor is a significant problem for alumina refineries. Microbial degradation is a low-cost solution to the problem, 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 acclimatised primarily with oxalate, both biofilms simultaneously oxidised 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. 2018 Journal Article http://hdl.handle.net/20.500.11937/69850 10.1016/j.jclepro.2018.03.153 Elsevier restricted |
| spellingShingle | Weerasinghe Mohottige, T. Cheng, K. Kaksonen, A. Sarukkalige, Priyantha Ranjan Ginige, M. Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title | Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title_full | Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title_fullStr | Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title_full_unstemmed | Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title_short | Influences of pH and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| title_sort | influences of ph and organic carbon on oxalate removal by alkaliphilic biofilms acclimatized to nitrogen-deficient and supplemented conditions |
| url | http://hdl.handle.net/20.500.11937/69850 |