Enhancement of growth and ferrous iron oxidation rates ofT. Ferrooxidans by electrochemical reduction of ferric iron

1986 ◽  
Vol 28 (12) ◽  
pp. 1867-1875 ◽  
Author(s):  
S. B. Yunker ◽  
J. M. Radovich
Keyword(s):  
Electrochemical Reduction ◽  
Ferrous Iron ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Oxidation Rates ◽  
Ferrous Iron Oxidation

Oxygen and carbon dioxide kinetic challenges for thermophilic mineral bioleaching processes

2004 ◽  
Vol 32 (2) ◽  
pp. 273-275 ◽  
Author(s):  
S.H. de Kock ◽  
P. Barnard ◽  
C.A. du Plessis
Keyword(s):  
Ferrous Iron ◽  
Large Scale ◽  
Elevated Temperatures ◽  
Ferrous Sulphate ◽  
Iron Oxidation ◽  
Co2 Concentration ◽  
Batch Cultures ◽  
Oxidation Rates ◽  
Ferrous Iron Oxidation ◽  
Oxygen Gas

Agitated bacterial tank bioleaching reactors are currently sparged with air to satisfy both oxygen and CO2 requirements of microbial cells. Under high-sulphide loading conditions, as is the case with high-grade metal sulphide concentrates, the microbial and chemical demand for oxygen is significantly increased during the bioleaching process. Sparging with enriched oxygen gas may offer an alternative process option to increased agitation and sparged aeration, to overcome the mass transfer difficulties at elevated temperatures where thermophilic Archaea, rather than Bacteria, are used. In the case of air sparging, the DO (dissolved oxygen) concentration in tank reactors could not be increased to a point where it would become inhibitory due to the limited oxygen content of air (20.9% O2). The use of enriched oxygen in such reactors at large scale does, however, pose its own set of process risks. The first aim of this investigation was, therefore, to determine the effects of various DO concentrations, in both the limiting and inhibitory ranges, on the microbial activity of Sulfolobus sp. U40813, a typical thermophilic mineral-leaching archaeon. Secondly, the effect of CO2 concentration on the rate of ferrous iron oxidation was investigated. Both the oxygen and CO2 kinetics were examined in controlled batch cultures at 78°C, using ferrous sulphate and potassium tetrathionate as energy sources. The optimal DO concentration for iron oxidation was found to be between 1.5 and 4.1 mg·l−1. The use of elevated DO concentrations (above 4.1 mg·l−1) inhibited the ferrous oxidation rates. The optimal gas CO2 concentration for ferrous iron oxidation was found to be in the range 7–17% (v/v). The iron oxidation rates were, however, severely limited at CO2 concentrations less than 7%, indicating that the CO2 supply was limiting in this range and inhibited the microbial growth rate.

Continuous biological ferrous iron oxidation in a submerged membrane bioreactor

2005 ◽  
Vol 51 (6-7) ◽  
pp. 59-68 ◽  
Author(s):  
D. Park ◽  
D.S. Lee ◽  
J.M. Park
Keyword(s):  
Ferrous Iron ◽  
Membrane Bioreactor ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Membrane Module ◽  
Microbial Oxidation ◽  
High Density Culture ◽  
Submerged Membrane Bioreactor ◽  
Ferrous Iron Oxidation ◽  
Iron Oxidizing Bacteria

Microbial oxidation of ferrous iron may be available alternative method of producing ferric iron, which is a reagent used for removal of H2S from biogas. In this study, a submerged membrane bioreactor (MBR) system was employed to oxidize ferrous iron to ferric iron. In the submerged MBR system, we could keep high concentration of iron-oxidizing bacteria and high oxidation rate of ferrous iron. There was membrane fouling caused by chemical precipitates such as K-jarosite and ferric phosphate. However, a strong acidity (pH 1.75) of solution and low ferrous iron concentration (below 3000 mg/l) significantly reduced the fouling of membrane module during the bioreactor operation. A fouled membrane module could be easily regenerated with a 1 M of sulfuric acid solution. In conclusion, the submerged MBR could be used for high-density culture of iron-oxidizing bacteria and for continuous ferrous iron oxidation. As far as our knowledge concerns, this is the first study on the application of a submerged MBR to high acidic conditions (below pH 2).

The Effect of Total Iron Concentration and Iron Speciation on the Rate of Ferrous Iron Oxidation Kinetics of Leptospirillum ferriphilum in Continuous Tank Systems

2007 ◽  
Vol 20-21 ◽  
pp. 447-451 ◽  
Author(s):  
Jochen Petersen ◽  
Tunde Victor Ojumu
Keyword(s):  
Oxidation Kinetics ◽  
Ferrous Iron ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Total Iron ◽  
Ferrous Iron Oxidation ◽  
Utilisation Rate ◽  
Kinetics Of ◽  
Total Iron Concentration

In this study the results from a systematic study of the oxidation kinetics of Leptospirillum ferriphilum in continuous culture at total iron concentrations ranging from 2 to12 g/L are reported. In all experiments the steady-state concentrations of ferrous iron were small and comparable, and at least 97% of was as ferric. Surprisingly, the specific ferrous iron utilisation rate decreased with increasing total iron concentration, while yield coefficients increased. It was noted that the biomass concentration in the reactor (as measured by both CO2 uptake rate and cell counts) dramatically increased with increasing total iron concentrations, whereas it stayed more or less the same over a wide range of dilution rates at a given total iron concentration. The experimental data was re-analysed in terms of ferrous iron kinetics using Monod kinetics with a ferric inhibition term. The results confirm that the maximum specific iron utilisation rate is itself a function of ferric iron concentration, declining with increasing concentration. It thus appears that high concentrations of ferric iron stimulate microbial growth while at the same time inhibiting the rate of ferrous iron oxidation. It is postulated that these phenomena are related, i.e. that more growth occurs to reduce the load on the individual cell, possibly by sharing some metabolic functions.

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.

Resistance of Moderately Thermophilic Acidophilic Microorganisms to Ferric Iron Ions

2017 ◽  
Vol 262 ◽  
pp. 471-475
Author(s):  
Aleksander Bulaev
Keyword(s):  
Ferrous Iron ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Iron Ions ◽  
Moderately Thermophilic ◽  
Ferrous Iron Oxidation ◽  
Low Concentrations ◽  
The Media ◽  
High Concentrations

Resistance of microorganisms predominating in biohydrometallurgical processes including bacteria of the genus Sulfobaсillus and archaea of the genus Acidiplasma to ferric iron ions was studied. Capabilities of the strains for growth and ferrous iron oxidation in the media containing high concentrations of ferric iron ions (of 250 to 1000 mM) were evaluated. Ferric iron ions significantly inhibited oxidative activity and growth of the studied microorganisms. It was revealed that bacteria of the genus Sulfobacillus were not able to oxidize ferrous iron actively when ferric iron concentration exceeded 500 mM, whereas archaea of the genus Acidiplasma completely oxidized ferrous iron in the medium containing 1000 mM of Fe3+. Growth of the microorganisms was inhibited by relatively low concentrations of ferric iron. Microorganisms did not grow in the medium containing more than 750 mM of Fe3+ and cells of all studied strains lysed in presence of high concentrations of ferric iron. It was shown, that archaea of the genus Acidiplasma of the family Ferroplasmaceae were more resistant to high concentrations of ferric iron than bacteria of the genus Sulfobacillus. The results obtained are important for understanding of the regularities of the formation of microbial communities performing technological processes.

Ferrous iron oxidation rates in the pycnocline of a permanently stratified lake

Chemosphere ◽  
2007 ◽  
Vol 66 (8) ◽  
pp. 1561-1570 ◽  
Author(s):  
Sergi Díez ◽  
Gregory O. Noonan ◽  
John K. MacFarlane ◽  
Philip M. Gschwend
Keyword(s):  
Ferrous Iron ◽  
Iron Oxidation ◽  
Stratified Lake ◽  
Oxidation Rates ◽  
Ferrous Iron Oxidation

Temperature Effects on the Iron Oxidation Kinetics of a Leptospirillum ferriphilum Dominated Culture at pH Below One

2007 ◽  
Vol 20-21 ◽  
pp. 465-468 ◽  
Author(s):  
Bestamin Özkaya ◽  
Pauliina Nurmi ◽  
Erkan Sahinkaya ◽  
Anna H. Kaksonen ◽  
Jaakko A. Puhakka
Keyword(s):  
Ferric Iron ◽  
Arrhenius Equation ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Leptospirillum Ferriphilum ◽  
Temperature Range ◽  
Oxidation Rates ◽  
Ferrous Iron Oxidation ◽  
Maximum Temperatures ◽  
Kinetics Of

In this study, ferrous iron oxidation rates of a Leptospirillum ferriphilum dominated culture were determined over the temperature range of 2-50oC at pH below one. The results show that at pH 0.9 the culture oxidizes iron within the temperature range of 10°C to 45°C. Using the Arrhenius equation, an Ea value of 89.9 ± 6.75 kJ/mol was calculated. From the data fitted to Ratkowsky Equation, the optimum, minimum and maximum temperatures were 35 ± 1.5, 9.96 ± 1.72 and 42.93 ± 0.64 °C for this culture, respectively. The redox potential of the solution becomes more positive, which was the maximum (650-700 mV) at temperatures between 19-40 oC due to completing biological oxidation and increasing in ferric iron concentration.

scholarly journals Ferrous Iron Oxidation by Immobilized on Refractory Clay Tiles

2008 ◽  
Vol 2 (1) ◽  
pp. 190-194 ◽  
Author(s):  
E.R. Donati
Keyword(s):  
Ferrous Iron ◽  
Ferric Iron ◽  
Immobilized Cells ◽  
Iron Oxidation ◽  
Cell Activity ◽  
Refractory Clay ◽  
High Cell ◽  
Ferrous Iron Oxidation ◽  
Glass Columns ◽  
Clay Tiles

Refractory clay tiles are composed of kaolin, which is the commercial name of clay, and this consists mainly of kaolinite mineral. Two such tiles and caowool packed in glass columns were used for the immobilization of Acidithiobacillus ferrooxidans cells in a ferrous iron medium, which was percolated through the supports. Colonization was carried out by several media replacements with no further inoculation until maximum ferric iron productivity was reached. One of the tiles was discarded due to the high iron precipitation during bacterial growth. The columns with the other supports were used for ferrous iron oxidation in batch and continuous flow modes of operation and these appeared to be promising supports for A. ferrooxidans. A ferrous iron oxidation rate of 14.5 mmol.l-1.h-1 was reached in one of the columns in the continuous culture. After being used for several cultures, pieces of tiles with immobilized cells were stored at 4 ºC. Samples at different times were incubated in ferrous medium and these showed high cell activity even after 6 months.

Sign in / Sign up

Export Citation Format

Share Document