Effect of pH and Temperature on Iron Oxidation by Mesophilic Mixed Iron Oxidizing Microflora

Abstract

The aim of the work described in this paper was to establish the effect of physical parameters such as pH and temperature on the microbial growth and iron oxidation rate of an isolated iron oxidizing bacterial strain from mine effluent. The bacterial lag phase was reduced to zero by repeated subculturing in fresh nutrient media. The rate of iron oxidation was considered as the growth rate of the microorganism in its logarithmic phase. Variation of pH showed an inadequate effect within the range from 1.5 to 2.5 ensuing growth flexibility in acidic medium. With variation of temperature from 293 to 313 K, the rate increased up to 303 K and gradually decreased beyond this temperature. At the optimized values of pH 2.0 and temperature 303 K, the iron oxidation rate was 2:17 Â 10 À4 kgÁm À3 Ás À1 .

A novel sequential process of bioleaching and chemical leaching for dissolving Ni, V, and Mo from spent petroleum refinery catalyst

“…The water sample was initially cultured in freshly prepared 9 K medium at pH 1.8 and 35°C (Kim et al, 2008). After several subculturing processes, the biomass was collected and subjected to 16S rDNA sequencing (carried out at the Korea Research Institute of Bioscience and Biotechnology).…”

Bioleaching of Complex Sulfides Concentrate and Correlation of Leaching Parameters Using Multivariate Data Analysis Technique

“…Quartz (SiO 2 ) was observed as a major gangue mineral. The leached residue showed three product layers, namely jarosite (NH 4 )Fe 3 (SO 4 ) 2 (OH) 6 , elemental sulfur (S) and anglesite (PbSO 4 ). Apart from these, the signal intensity of sulfide matrix decreased while that of quartz increased indicating dissolution of the sulfide matrix during leaching.…”

“…The microorganisms oxidize Fe(II) and elemental sulfur to Fe(III) and H 2 SO 4 , respectively, at low acid as well as high metal ion concentrations. 5,6) These properties are unique for these types of microorganisms as no other species can survive under these extreme conditions. The applicability of this technique is not limited to heap leaching, but has been extended to reactor leaching.…”

Dissolution Kinetics of Complex Sulfides Using Acidophilic Microorganisms

“…The bacteria culture was mixed one grown in 9 K media. 10) Before conducting the leaching studies, the bacteria culture was adapted to the concentrate. All leaching experiments were conducted using 5 days old fully grown cultures.…”

“…Basically, the microorganisms oxidize Fe(II) to Fe(III) and S to SO 4 , which facilitates the transfer of electrons during their respiration process. 10,11) However, slow leaching kinetics can lead to an increased retention time during bioleaching. Despite this, little improvement in the leaching of minerals has been achieved through molecular genetics; 12) therefore, concerted efforts focused on various parameters that affect the leaching kinetics such as particle size, ore mineralogy, bacterial activity and population and oxygen transfer are required.…”