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Browsing by Author "van Hille, Robert P"

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Attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum cultured under varying conditions to pyrite, chalcopyrite, low-grade ore and quartz in a packed column reactor

Author: Africa, Cindy-Jade ; van Hille, Robert P ; Harrison, Susan T L Date: 2012 The attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum spp. grown on ferrous medium or adapted to a pyrite mineral concentrate to four mineral substrata, namely, chalcopyrite and pyrite concentrates, a low-grade ... Read more
Development of a method to assay the microbial population in heap bioleaching operations

Author: Coram-Uliana, Nicolette J ; van Hille, Robert P ; Kohr, William J ; Harrison, Susan T L Date: 2005 Heap bioleaching is an economically viable approach to the mining of low-grade ores. Oxidation is microbially assisted, involving a consortium of microorganisms that together span the mesophilic to extreme thermophilic range of temperatures ... Read more
Effect of culture conditions on the competition between lactate oxidisers and fermenters in a biological sulfate reduction system

Author: Oyekola, Oluwaseun O ; Harrison, Susan T L ; van Hille, Robert P Date: 2012 Kinetic constants (μmax and Ks) describing the predominance of lactate oxidation and fermentation were determined in chemostat cultures. The kinetics of sulfate reduction and lactate utilization were determined from 0.5 to 5 d residence times ... Read more c b n d
The effect of nitrogen limitation on lipid productivity and cell composition in Chlorella vulgaris

Author: Griffiths, Melinda J ; van Hille, Robert P ; Harrison, Susan T L Date: 2014 Chlorella vulgaris accumulates lipid under nitrogen limitation, but at the expense of biomass productivity. Due to this tradeoff, improved lipid productivity may be compromised, despite higher lipid content. To determine the optimal degree ... Read more
The effect of nitrogen limitation on lipid productivity and cell composition in Chlorella vulgaris

Author: Griffiths, Melinda J ; van Hille, Robert P ; Harrison, Susan T L Date: 2014 Chlorella vulgaris accumulates lipid under nitrogen limitation, but at the expense of biomass productivity. Due to this tradeoff, improved lipid productivity may be compromised, despite higher lipid content. To determine the optimal degree ... Read more
The effect of nutrient supplementation on growth and leaching performance of bioleaching bacteria

Author: van Hille, Robert P ; Bromfield, L V ; Botha, S S ; Jones, G ; van Zyl, A W ; Harrison, Susan T L Date: 2009 Heap bioleaching operations are often faced with extended and unpredictable lag periods after inoculation, prior to the establishment of a stable oxidising environment, during which the heap is fully colonised or the inoculum overcomes the ... Read more
Evaluation of the ASTERTM process in the presence of suspended solids

Author: van Zyl, Andries W ; Huddy, Robert ; Harrison, Susan T L ; van Hille, Robert P Date: 2014 The ability to recycle and reuse process water is a major contributing factor toward increased sustainability in the mining industry. However, the presence of toxic compounds has prevented this in most bioleaching operations. The ASTERTM ... Read more
The generation of toxic reactive oxygen species (ROS) from mechanically activated sulphide concentrates and its effect on thermophilic bioleaching.

Author: Jones, Gavin C ; Corin, Kirsten C ; van Hille, Robert P ; Harrison, Susan T L Date: 2011 Two types of laboratory mills, planetary and vibratory, were used to activate sulphide mineral concentrates mechanically before thermophilic (bio)leaching. These samples were analysed in terms of particle size, surface area, density, SEM, XRD ... Read more
In situ investigation and visualisation of microbial attachment and colonisation in a heap bioleach environment: the novel biofilm reactor

Author: Africa, Cindy-Jade ; Harrison, Susan T L ; Becker, Megan ; van Hille, Robert P Date: 2010 In this paper, the development of a novel means of investigating the attachment and subsequent biofilm formation of mineral bioleaching micro-organisms to mineral surfaces in situ is described. The protocol was developed to investigate the ... Read more
Interference by pigment in the estimation of microalgal biomass concentration by optical density

Author: Griffiths, Melinda J ; Garcin, Clive ; van Hille, Robert P ; Harrison, Susan T L Date: 2011 Optical density is used as a convenient indirect measurement of biomass concentration in microbial cell suspensions. Absorbance of light by a suspension can be related directly to cell density using a suitable standard curve. However, ... Read more c b n d
Investigating heap leaching – the effect of feed iron concentration on bioleaching performance

Author: van Hille, Robert P ; van Zyl, Andries W ; Spurr, Nicholas R L ; Harrison, Susan T L Date: 2010 This paper describes an investigation into the effect of iron concentration in the leach solution on the bioleaching of a low grade copper ore, where chalcopyrite was the dominant copper sulphide. The concentration of dissolved iron is primarily ... Read more
Investigation and in situ visualisation of interfacial interactions of thermophilic microorganisms with metal-sulphides in a simulated heap environment

Author: Africa, Cindy-Jade ; van Hille, Robert P ; Sand, Wolfgang ; Harrison, Susan T L Date: 2013 This study sought to provide a better understanding of the dynamics of microbial-metal sulphide interfacial processes relevant to heap bioleaching. Attachment and subsequent biofilm formation by Metallosphaera hakonensis (M. hakonensis) on ... Read more
Kinetic analysis of biological sulphate reduction using lactate as carbon source and electron donor: Effect of sulphate concentration.

Author: Oyekola, Oluwaseun O ; van Hille, Robert P ; Harrison, Susan T L Date: 2010 This study investigated the effect of feed sulphate concentration on the kinetics of anaerobic sulphate reduction by a mixed SRB culture, using lactate as the sole carbon source and electron donor. Chemostat cultures were operated across a ... Read more
Lipid productivity, settling potential and fatty acid profile of 11 microalgal species grown under nitrogen replete and limited conditions

Author: Griffiths, Melinda J ; van Hille, Robert P ; Harrison, Susan T L Date: 2012 Microalgae are a promising alternative source of oil for biodiesel production. Identification of a species with desirable characteristics is a key component towards achieving economic feasibility for the process. This has been compromised by ... Read more
The microbial ecology of moderately thermophilic mineral leaching reactors: the effect of solids loading and organic carbon supplementation on reactor performance

Author: Dean, Jonathan ; van Hille, Robert P ; Harrison, Susan T L Date: Nov 2015 Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential ... Read more
The microbial ecology of moderately thermophilic mineral leaching reactors: the effect of solids loading and organic carbon supplementation on reactor performance

Author: Dean, Jonathan ; van Hille, Robert P ; Harrison, Susan T L Date: 2015 Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential ... Read more
Study of anaerobic lactate metabolism under biosulphidogenic conditions

Author: Oyekola, Oluwaseun A ; van Hille, Robert P ; Harrison, Susan T L Date: 2009 Biological sulfate reduction (BSR) has been reported to have potential for the treatment of acid mine drainage (AMD). The provision of a suitable carbon source and electron donor for this process remains a challenge. Lactate offers potential ... Read more
Sulfide mineral induced oxidative stress as a limiting factor in tank bioleaching performance

Author: Jones, Gavin ; van Hille, Robert P ; Harrison, Susan T L Date: 2009 In tank bioleaching, decreasing particle size of milled concentrates has been shown to improve leaching performance owing to increased mineral surface area and mechanical activation effects of fine mineral particles. However, evidence suggests ... Read more
The effect of sulfide concentrate mineralogy and texture on Reactive Oxygen Species (ROS) generation

Author: Jones, Gavin C ; Becker, Megan ; van Hille, Robert P ; Harrison, Susan T L Date: ROS The generation of Reactive Oxygen Species (ROS), H2O2 and radical dotOH, has been observed from sulfide mineral containing particles in acidic solutions. The implications of this phenomenon, as a potential microbial stress-causing effect, ... Read more

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Browsing by Author "van Hille, Robert P"

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