Effect of Operating Conditions on the Chemical Phosphate Removal Using during Ferrous Iron Oxidation

2013 ◽  
Vol 807-809 ◽  
pp. 478-485 ◽  
Author(s):  
Ting Li ◽  
Wen Yi Dong ◽  
Hong Jie Wang ◽  
Jin Nan Lin ◽  
Feng Ouyang ◽  
...  

In this study, the effect of operating parameters and the co-existing ions on the phosphate removal during the ferrous iron oxidation was investigated. Results showed that with the increase of DO and [Fe (II)]0, the final phosphate removal rate both increased. But with increasing of pH, the final phosphate removal rate firstly increased and then decreased when the pH was higher than 8.0. The co-existing ions affected the final removal rate significantly, and the kinetics of phosphate removal followed the pseudo-first-order kinetic model. The corresponding kobs trends for the cation followed the order of Cu2+>Mn2+>Zn2+>NH4+-N. The presence of Cu2+ promoted the phosphate removal significantly. Compared with the control, , the time required to achieve 40 % phosphate removal rate, at the condition of 0.5 mg/L Cu2+, reduced from 60 min to 10 s. However, the selective anions inhibited the phosphate removal, due to the formation of Fe-anions complexes. The effect of selective anions on the phosphate removal rate constant decreased in the order of SO42->Cl-> NO3-.

2005 ◽  
Vol 11 (2) ◽  
pp. 59-62 ◽  
Author(s):  
Dragisa Savic ◽  
Miodrag Lazic ◽  
Vlada Veljkovic ◽  
Miroslav Vrvic

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.


2007 ◽  
Vol 20-21 ◽  
pp. 517-520
Author(s):  
Pablo S. Pina ◽  
V.A. Leão ◽  
C.A. Silva ◽  
S.N. Medrício ◽  
J. Frenay

2007 ◽  
Vol 20-21 ◽  
pp. 447-451 ◽  
Author(s):  
Jochen Petersen ◽  
Tunde Victor Ojumu

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.


2009 ◽  
Vol 71-73 ◽  
pp. 259-262 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen

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.


1982 ◽  
Vol 133 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Alan A. DiSpirito ◽  
Olli H. Tuovinen

2009 ◽  
Vol 71-73 ◽  
pp. 255-258 ◽  
Author(s):  
K. Penev ◽  
D. Karamanev

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.


1993 ◽  
Vol 11 (1) ◽  
pp. 57-63 ◽  
Author(s):  
C. Chavarie ◽  
D. Karamanev ◽  
F. Godard ◽  
A. Garnier ◽  
G. André

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