A reason for different sorption efficiencies might be the electro-chemical properties of the metal ions. Competitive biosorption of copper, cadmium, nickel and zinc from metal ion mixtures using anaerobically digested sludge Artola, A. Minera San Jos6 Avino, Durango, Mrxico, was used in all experiments. At 35 and 68~ the iron in solution was lower than at 45~ what could be related to a higher precipitation of jarosites, which is favored at high pH at 35 ~ C pH was about 2 and high temperature. The first stage of leaching corresponds to chemical dissolution of simple sulphides such as chalcocite and digenite in an acid medium. This will require that research is initiated into the molecular biology of moderate 35 and hyper-thermophilic 51 organisms most hyperthermophiles are Archaea. The evolution of the pH of the solution Figure l a indicates bacterial activity after day tenth with generation of H The E evolution Figure lb shows the dissolution of simple sulphides during the first 20 days and, further, chalcopyrite dissolution.
The spectra were recorded as described previously 16. This value is significatively higher than the total metal adsorption found in binary systems where maximum values of 1. The Freundlich adsorption isotherm describes a multilayer adsorption. On a positive note, substantial research has been conducted to confront the challenge. Proceedings of the 18th International Biohydrometallkurgy Symposium Eds. When the specific uptake of Cd per cell was plotted against time, it became obvious that the cell capacity to sequester the metals peaked at 2 hour-incubation where cells were growing exponentially in the beads without showing any leakage yet Figure 5.
Biomining techniques represent attractive alternatives to conventional methods of mining since in general they are less energy-intensive and less polluting than chemical ones. Bacterial oxidation of pure arsenopyrite by a mixed culture Malatt, K. Percent of iron leached with mesophilic, moderate thermophilic and thermophilic microorganisms. Minerals Engineering July 2013 48: 108—115. For this purpose, a genetic transfer system between Escherichia coli and T. An attractive alternative for metal recovery could be the use of microorganisms due to its low cost and relatively fewer pollution problems compared with conventional hydrometallurgical and pyrometallurgical processes. In this paper the interaction between cytochrome c4 and rusticyanin is studied and the purification and characterization of a novel cytochrome which may take part in the respiratory electron transport chain of T.
Cloning of metal-resistance conferring genes from an Acidocella strain Ghosh, S. The sizes and mapping of the genomes of the other biomining bacteria covered in this review have not been reported. We therefore propose an analogous reaction for the T. Minerals Engineering 24 11 , 1209-1214. Direct versus indirect bioleaching Sand,W. A single copy of the rus gene was present in T. Study of the proteins involved in the resistance of cadmium of Thiobacillus ferrooxidans Taira, M.
In spite of this the two bacteria share much more in common from a molecular genetic point of view than might be imagined from their differences in physiology and the ecological niches which they occupy. To investigate the effect of microorganism concentration on the biosorption of heavy metal ions, the quantity of dried cells was increased while the metal concentration and solution volumes were kept constant. Minerals Engineering 2012 39: 156—164. We were able to get isolated clones only with the 2:2 m e d i u m described in 4. A novel mineral processing by flotation using Thiobacillus ferrooxidans Nagaoka, T. Although all the classical biohydrometallurgical topics - e.
However, conventional approaches cannot be used to process such resources due to high capital cost and energy, also causing environmental pollution. Understanding the microbiology of bioheaps is key to advancing commercial bioheap applications. The positions of the ironand sulfur-oxidising bacteria are indicated on a diagram showing the 24 bacterial divisions previously recognised. One cause for concern regarding the efficiency of the process in regards to the organism is the makeup of the microbial community in a heap reactor. The heating of pulp in bioreactors causes exothermic lysis of microorganisms and cessation of the production process.
Continuous pilot scale testwork has shown that thermophiles achieve efficient bioleaching of primary copper sulphide and nickel sulphide concentrates, giving much higher recoveries than achieved by bioleaching with a mesophile or moderate thermophile culture. Specific metal sequestering acidophilic fungi Durán, C. Biosorption of heavy metal ions from aqueous and cyanide solutions using fungal biomass Natarajan, K. On the melanine and humic acids interaction with clay minerals Kadoshnikov, V. This paper aims to quantify and characterise by chemical and physico-chemical means, the functional groups of the biomass in lead biosorption. Figure 3 shows the pH evolution versus time for all experiments carried out with Zn. From the papers in these volumes it is clear that environmental issues are already of great interest to the biohydrometallurgical community.
Sastre, Hydrometallurgy, 40 1996 195. This Page Intentionally Left Blank 59 The use o f immunoelectron microscopy to analyze surface components of Thiobacillusferrooxidans grown under different conditions O. It is to be noted that, by alkaline precipitation, such low residual concentrations would require pH of 10. A large group of negatively charged macromolecules on the microbial cell wall have shown selective affinities to various types of metal cations 4,5,6,7. Among these, the most potential of them viz. Continuous pilot scale and laboratory batch testwork has been carried out with adapted mesophile bacterial cultures at 40°C - 45°C, moderate thermophile cultures at 50°C - 55°C and thermophile cultures at 65°C - 85°C.
Rawlings Department of Microbiology, University of Stellenbosch, Stellenbosch, 7600, South Africa. Leaching of Turkish copper ore samples with Thiobacillus ferrooxidans Dogan, M. Sulphate reduction optimization in the presence of Desulfotomaculum acetoxidans and Desulfobacter postgatei species. The equilibrium adsorption yield was defined as the ratio of the adsorbed metal ion concentration, Cads mg 1-1 at equilibrium to the initial metal ion concentration, Ci mg I-1. Effect of different compounds on the yield and on the growth of the T. The experience accumulated and the outlook for technology development Tsezos, M. Over the range investigated 20 ~ - 60 ~ temperature-related effects were not significant.