Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching

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dc.contributor.authorNgoma, I Emmanuel
dc.contributor.authorOjumu, Tunde V
dc.contributor.authorHarrison, Susan T L
dc.date.accessioned2018-03-01T08:15:58Z
dc.date.available2018-03-01T08:15:58Z
dc.date.issued2015-05-01
dc.description.abstractDuring start-up of heap bioleaching, low grade ores are typically treated with acid for agglomeration and to combat the acid neutralising capacity of the gangue minerals. This may stress the bioleaching inocula, particularly upon inoculation during ore agglomeration. Acid addition for agglomeration varies across operations, ore types and their neutralising capacity, with limited information published on recommended concentrations. The initial pH in the agglomeration mix is typically below pH 1.0 and may be as low as pH 0.5. This paper investigates the effect of acid stress in terms of initial acid concentration and exposure duration in submerged culture on mesophilic bacteria typically implicated in mineral sulphide bioleaching and critical for heap colonisation at start-up. Following acid stress, cultures were returned to standard operating conditions in batch stirred slurry reactors and their performance assessed in terms of mineral leach rates, ferrous oxidation and the rate of microbial growth. Increasing acid stress resulted in an increase in the lag period before onset of microbial growth and iron oxidation. Following adaptation, typical growth and ferrous iron oxidation rates were observed under low stress conditions while reduction in the rate and extent of microbial growth and ferrous iron oxidation persisted at extreme conditions. A reduction in yield (microbial cells produced per kg iron oxidised) was observed with increased acid concentration over comparative times. Microbial speciation analysis indicated a substantial decrease in the diversity of surviving bacterial species.en_ZA
dc.identifier.apacitationNgoma, I. E., Ojumu, T. V., & Harrison, S. T. L. (2015). Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching. <i>Minerals Engineering</i>, http://hdl.handle.net/11427/27609en_ZA
dc.identifier.chicagocitationNgoma, I Emmanuel, Tunde V Ojumu, and Susan T L Harrison "Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching." <i>Minerals Engineering</i> (2015) http://hdl.handle.net/11427/27609en_ZA
dc.identifier.citationNgoma IE, Ojumu TV, Harrison STL, 2015, Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching, Minerals Engineering, Volume 75, 1 May 2015, Pages 6-13en_ZA
dc.identifier.ris TY - Journal Article AU - Ngoma, I Emmanuel AU - Ojumu, Tunde V AU - Harrison, Susan T L AB - During start-up of heap bioleaching, low grade ores are typically treated with acid for agglomeration and to combat the acid neutralising capacity of the gangue minerals. This may stress the bioleaching inocula, particularly upon inoculation during ore agglomeration. Acid addition for agglomeration varies across operations, ore types and their neutralising capacity, with limited information published on recommended concentrations. The initial pH in the agglomeration mix is typically below pH 1.0 and may be as low as pH 0.5. This paper investigates the effect of acid stress in terms of initial acid concentration and exposure duration in submerged culture on mesophilic bacteria typically implicated in mineral sulphide bioleaching and critical for heap colonisation at start-up. Following acid stress, cultures were returned to standard operating conditions in batch stirred slurry reactors and their performance assessed in terms of mineral leach rates, ferrous oxidation and the rate of microbial growth. Increasing acid stress resulted in an increase in the lag period before onset of microbial growth and iron oxidation. Following adaptation, typical growth and ferrous iron oxidation rates were observed under low stress conditions while reduction in the rate and extent of microbial growth and ferrous iron oxidation persisted at extreme conditions. A reduction in yield (microbial cells produced per kg iron oxidised) was observed with increased acid concentration over comparative times. Microbial speciation analysis indicated a substantial decrease in the diversity of surviving bacterial species. DA - 2015-05-01 DB - OpenUCT DP - University of Cape Town J1 - Minerals Engineering LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching TI - Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching UR - http://hdl.handle.net/11427/27609 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/27609
dc.identifier.vancouvercitationNgoma IE, Ojumu TV, Harrison STL. Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching. Minerals Engineering. 2015; http://hdl.handle.net/11427/27609.en_ZA
dc.languageengen_ZA
dc.publisherElsevieren_ZA
dc.publisher.departmentCentre for Bioprocess Engineering Research
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en_ZA
dc.sourceMinerals Engineeringen_ZA
dc.source.urihttps://www.sciencedirect.com/journal/minerals-engineering
dc.titleInvestigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleachingen_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsAcid stressen_ZA
uct.subject.keywordsAgglomerationen_ZA
uct.subject.keywordsMineral bioleachingen_ZA
uct.subject.keywordspH controlen_ZA
uct.subject.keywordsProcess optimisationen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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