The Effect of Aluminium and Magnesium Sulphate on the Rate of Ferrous Iron Oxidation by Leptospirillum ferriphilum in Continuous Culture

2007 ◽  
Vol 20-21 ◽  
pp. 156-159 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen ◽  
Geoffrey S. Hansford
Keyword(s):  
Continuous Culture ◽  
Ferrous Iron ◽  
Oxidation Process ◽  
Iron Oxidation ◽  
Leach Solution ◽  
Potential Region ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
Low Concentrations ◽  
Kinetics Of

In heap bioleaching the dissolution of gangue minerals from igneous ore materials can lead to the build-up of considerable concentrations of Mg and Al sulphates in the recycled leach solution. This may interfere with microbial ferrous iron oxidation, which drives the oxidation of the target minerals. The kinetics of the oxidation process have been well studied for Leptospirillum and Acidithiobacillus species in tank systems. Although not directly comparable, kinetic parameters derived for tank systems do apply also for heap bioleach conditions. In the present study the effect of solution concentrations of Mg and Al as sulphate at individual concentrations of 0 to 10 g/L and combined concentrations 0 to 16 g/L each has been investigated in continuous culture using Leptospirillum ferriphilum. Increasing the concentrations of the salts increasingly depresses the rate of ferrous iron oxidation and also shifts the viable range more and more into the low potential region. Al significantly reduces the amount of carbon maintained in the reactor (assumed to be commensurate with biomass), whereas Mg actually enhances it at low concentrations. In both cases, however, the rate is always depressed. The results indicate that heap cultures are likely to perform sub-optimally in those operations where build-up of dissolved gangue minerals is not controlled.

Kinetics of Microbial Ferrous-Iron Oxidation by Leptospirillum Ferriphilum: Effect of Ferric-Iron on Biomass Growth

2009 ◽  
Vol 71-73 ◽  
pp. 259-262 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen
Keyword(s):  
Ferrous Iron ◽  
Microbial Growth ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Biomass Concentration ◽  
Reaction Conditions ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
Kinetics Of

The kinetics of microbial ferrous-iron oxidation have been well studied as it is a critical sub-process in bioleaching of sulphide minerals. Exhaustive studies in continuous culture have been carried out recently, investigating the effects of conditions relevant to heap bioleaching on the microbial ferrous-iron oxidation by Leptospirillum ferriphilum [1-3]. It was postulated that ferric-iron, which is known to be inhibitory, also acts as a stress stimulus, promoting microbial growth at higher total iron concentration. This paper investigates this phenomenon further, by comparing tests run with pure ferrous-iron feeds against those where the feed is partially oxidised to ferric at comparable concentrations. The findings clearly suggest that, contrary to reactor theory, it is indeed ferrous iron concentration in the reactor feed that determines biomass concentration and that ferric iron concentration has little effect on microbial growth. Further mathematical analysis shows that the phenomenon can be explained on the basis of the Pirt equation and the particular reaction conditions employed in the test work.

Kinetics of Ferrous Iron Oxidation by Leptospirillum Ferriphilum at Moderate to High Total Iron Concentrations

2009 ◽  
Vol 71-73 ◽  
pp. 255-258 ◽  
Author(s):  
K. Penev ◽  
D. Karamanev
Keyword(s):  
Ferrous Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Total Iron ◽  
Effect Of Temperature ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
High Concentrations ◽  
Kinetics Of ◽  
Total Iron Concentration

The effects of temperature, pH and iron concentration on the kinetics of ferrous iron biooxidation by a free suspended culture of Leptospirillum ferriphilum were studied in shake flasks and a circulating bed bioreactor at moderate to high total iron concentration. The kinetic study showed that there are two distinct modes of iron biooxidation: growth associated and non-growth associated, depending on the pH of the medium. There were also distinctive maxima of the effect of temperature and pH on the rate of biooxidation. A kinetic model of the process was proposed, based on an electrochemical-enzymatic model. The proposed model indicates that at moderate to high concentrations (above ~12 g/L), the total iron concentration becomes the single most prominent inhibiting factor.

scholarly journals A kinetic model of ferrous iron oxidation by Acidithiobacillus ferrooxidans in a batch culture

2005 ◽  
Vol 11 (2) ◽  
pp. 59-62 ◽  
Author(s):  
Dragisa Savic ◽  
Miodrag Lazic ◽  
Vlada Veljkovic ◽  
Miroslav Vrvic
Keyword(s):  
Kinetic Model ◽  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Bubble Column ◽  
Iron Oxidation ◽  
Yield Coefficient ◽  
Transfer Rates ◽  
Ferrous Iron Oxidation ◽  
Menten Kinetic ◽  
Kinetics Of

The batch oxidation kinetics of ferrous iron by Acidithiobacillus ferrooxidans were examined at different oxygen transfer rates and pH in an aerated stirred tank and a bubble column. The microbial growth, oxygen consumption rate and ferrous and ferric iron were monitored during the biooxidation. A kinetic model was established on the basis of the Michaelis-Menten kinetic equation for bacterial growth and the constants estimated from experimental data (maximum specific growth rate 0.069 h-1, saturation constant 2.9 g/dm3, and biomass yield coefficient based on ferrous iron 0.003 gd.w./gFe). Values calculated from the model agreed well with the experimental ones regardless of the bioreactor type and pH conditions.

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