Bioleaching of Heavy Metals by Sulfur Oxidizing Bacteria: A Review (original) (raw)
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Water Research, 2004
The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfuroxidizing bacteria were investigated in an airlift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3 g/l.
Bioleaching of heavy metals from a low-grade mining ore using Aspergillus niger
Journal of hazardous materials, 2004
The main concern of this study is to develop a feasible and economical technique to microbially recover metals from oxide low-grade ores. Owing to the significant quantities of metals that are embodied in low-grade ores and mining residues, these are potential viable sources of metals. In addition, they potentially endanger the environment, as the metals they contain may be released to the environment in hazardous form. Hence, mining industries are seeking an efficient, economic technique to handle these ores. Pyrometallurgical and hydrometallurgical techniques are either very expensive, energy intensive or have a negative impact on the environment. For these reasons, biohydrometallurgical techniques are coming into perspective. In this study, by employing Aspergillus niger, the feasibility of recovery of metals from a mining residue is shown. A. niger exhibits good potential in generating a variety of organic acids effective for metal solubilization. Organic acid effectiveness was enhanced when sulfuric acid was added to the medium. Different agricultural wastes such as potato peels were tested. In addition, different auxiliary processes were evaluated in order to either elevate the efficiency or reduce costs. Finally, maximum solubilization of 68%, 46% and 34% were achieved for copper, zinc and nickel, respectively. Also iron co-dissolution was minimized as only 7% removal occurred.
Current Research Trends of Microbiological Leaching for Metal Recovery from Industrial Wastes
The concept of microbiological leaching have played a greater role to recover valuable metals from various sulfide minerals or low grade ores during the middle era of twentieth century and that continued till the end of the century. Slowly, due to depletion of ore/minerals, and implementation of stricter environmental rules, microbiological leaching process has been shifted for its application to recover valuable metals from the different industrial wastes. Although there are conventional processes, physical and chemical methods, for treatment of industrial wastes, these technologies have certain limitation in practical applications. The microbial method is an efficient and cost-effective alternative to chemical and physical methods because of its low demand for energy, material and less generation of waste byproduct. There are several industrial wastes that possess toxic elements and thus when leached into atmosphere cause serious environmental problem. Among the wastes, spent petroleum catalysts, electronic scraps, lithium battery wastes, sewage sludge, fly ash etc. are some of the major industrially produced wastes. These solid wastes mostly contain Ni, V, Mo, Co, Cu, Pb, Zn, and Cr like heavy metals in it. The major microorganisms those play the significant role in recovery of heavy metals from such wastes belong to acidophilic group. These acidophilic groups thrive in acidic pH ranges (pH 2.0 – 4.0) and help in dissolving the metals from solid phase of wastes into the aqueous phase. Among the bacteria Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans, and Sulfolobus sp., are well known consortia for the bioleaching activity while Penicillium, and Aspergillus niger are some fungi those help in metal leaching process. The current chapter will be thoroughly studied about the application of these acidophilic microorganisms for the metal recovery from different industrial wastes. The key microorganisms and their bioleaching mechanism have been focused here.
Bioleaching: A Promising Method of Selective Leaching of Metals
MINERAL PROCESSING TECHNOLOGY(MPT), 2017
Leaching is a common practice of hydro-metallurgical operations in mineral extraction. The Bioleaching also called Bio-hydroleaching, have played greater role to recover of valuable metals from various minerals of oxides and sulphide ores especially for low grade ores. An increase in research and development for laboratory scale to large-scale industrial operations of Bioleaching finds attention in now a day. Bioleaching is a simple and effective technology for metal extraction from low-grade ores and mineral concentrates. With little complexity in attaining operational conditions of Bioleaching that are distinct from the conventional practices of leaching of oxides or sulphide by either acid-base reactions or redox chemical reactions. The kinetic mechanisms and feasibility for selective digestion of metals from mineral ores can be discussed. Bacterial leaching type in an acid environment at pH values usually between 1.5 and 3 at which most metal ions remain in solution. They are much cleaner than the traditional and are used to recover metal like - copper, zinc, lead, nickel, gold, silver, cobalt, etc. Stirred tank bioleaching has been commercialized for cobalt recovery and for bio-oxidation of refractory gold ores. The microorganisms used in bioleaching type, like: Thiobacillus, Leptospirillum, Acidithiobacillus, Thermophilic bacteria, Heterotrophic bacteria, Fungi, etc. The mechanism of bioleaching is done by Direct and indirect bacterial leaching. Bioleaching has also some potential for metal recovery and detoxification of industrial waste products, sewage sludge and soil contaminated with heavy metals. In the present work, present trends in practices of Bioleaching and its advantages for recovery of metals from mineral ores, industrial and sewage wastages will be discussed. The kinetic understanding of selectivity cases with different bacterial and microorganisms will be discussed. Along with the feasibility of adoption of such practice and conversion of laboratory investigations to industrial Leaching practices.
The Use of Microorganisms in the Bioleaching of Soils Polluted with Heavy Metals
2019
This paper shows researches in order to extract Cr, Cu and Ni from the polluted soils. Research is based on preliminary studies regarding the usage of <em>Thiobacillus ferrooxidans</em> bacterium (9K medium) for bioleaching of soil polluted with heavy metal (Cu, Cr and Ni). The microorganisms (<em>Thiobacillus ferooxidans</em>) selected directly from polluted soil samples were used in this experimental work. Soil samples used in the experimental research were taken from an area polluted with heavy metals from Romania. The soil samples are subjected to the cleaning process using the 9K medium solution (20 mL and 40 mL, respectively), stirred 200 rpm for 20 hours at a controlled temperature (30 ˚C). During the experiment (0, 2, 4, 8 and 20 h), liquid samples have been extracted and analyzed using the Atomic Absorption Spectrophotometer AA-6800 (AAS) in order to determine the Cr, Cu and Ni concentration. Experiments led to the conclusion that these soils can be ...
Bioleaching of Heavy Metals from Mine Tailings by Aspergillus fumigatus
Bioremediation Journal, 2012
The bioleaching experiment was conducted for the removal of heavy metals from mine tailings. A fungal strain was isolated from the gold mine tailings and it has been identified as Aspergillus fumigatus based on its 18S rDNA analysis. Bioleaching using A. fumigatus was carried out in bioleaching step processes (one-step and two-step) at various tailings concentrations (1%, 2%, 4%, and 8% [w/v]). In the one-step bioleaching process where fungi were cultivated in the presence of the tailings, concentration of oxalic acid was the highest among the organic acids produced. On the other hand, in the two-step bioleaching process where the metabolic products of fungal growth, which have been separated from its biomass, were used, citric acid was dominant. In the one-step process, the highest As (62%), Fe (58%), Mn (100%), and Zn (54%) removals were observed at the lowest tailings concentration (1%). The removal of Pb at 1% tailings concentration in the one-step process was 56%, whereas 88% removal was achieved in the two-step process where citric acid was dominant. In general, heavy metals removal efficiency decreased with increased tailings of the concentration in both bioleaching processes. This study shows the possibility of using A. fumigatus to bioleach hazardous heavy meals from gold mine tailings.
Science of The Total Environment, 2019
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Chemosphere, 2006
The application of two different types of elemental sulfur (S 0) was studied to evaluate the efficiency on bioleaching of heavy metals from contaminated sediments. Bioleaching tests were performed in suspension and in the solid-bed with a heavy metal contaminated sediment using commercial sulfur powder (technical sulfur) or a microbially produced sulfur waste (biological sulfur) as substrate for the indigenous sulfur-oxidizing bacteria and thus as acid source. Generally, using biological sulfur during suspension leaching yielded in considerably better results than technical sulfur. The equilibrium in acidification, sulfur oxidation and metal solubilization was reached already after 10-14 d of leaching depending upon the amount of sulfur added. The metal removal after 28 d of leaching was higher when biological sulfur was used. The biological sulfur added was oxidized with high rate, and no residual S 0 was detectable in the sediment samples after leaching. The observed effects are attributable to the hydrophilic properties of the biologically produced sulfur particles resulting in an increased bioavailability for the Acidithiobacilli. In column experiments only poor effects on the kinetics of the leaching parameters were observed replacing technical sulfur by biological sulfur, and the overall metal removal was almost the same for both types of S 0. Therefore, under the conditions of solid-bed leaching the rate of sulfur oxidation and metal solubilization is more strongly affected by transport phenomena than by microbial conversion processes attributed to different physicochemical properties of the sulfur sources. The results indicate that the application of biological sulfur provides a suitable means for improving the efficiency of suspension leaching treatments by shortening the leaching time. Solid-bed leaching treatments may benefit from the reuse of biological sulfur by reducing the costs for material and operating.
BIOREMEDIATION OF HEAVY METALS USING BIOSURFACTANT PRODUCING MICROORGANISMS
The present study was carried out to evaluate degradation of heavy metals in effluent waste water samples using microorganisms. The physical and chemical properties of the effluent samples were analyzed using standard methods. The soil sample collected from the heavy metal contaminated sites was subjected to serial dilution and streak-plating methods and six different strains were isolated from the samples. The activity of the isolates for hemolysis was studied on the Blood-Agar plates. The isolated strains were studied for its biochemical and morphological characteristics. The dark-blue colonies were observed by CTAB method, which confirmed the anionic bio surfactant produced by the isolate. The isolates were subjected to other screening tests like emulsification activity and oil displacement technique. These strains were used in the degradation of heavy metals present in the effluent waste water samples. The organism KDM 4 showed better degradation with 93.18% ability in reducing zinc when incubated for 72 hours and 86.36% when incubated for 24 hours in sample 3. The lead reduction was found to be 84.13% by the organism KDM3 when incubated at 37°C for 72 hours incubation. The chromium was reduced by the organism KDM 6 with 87.9% ability when incubated for 72 hours. The organisms had capacity to reduce the heavy metals depending on the factors like time and concentration of inoculum. As the time of incubation increases, more reduction was observed. The least amount of degradation was found in the organism KDM5 with only 27.08%. The percentage of reduction of heavy metals varies from one sample to another sample. INTRODUCTION Pollution due to chemicals including heavy metals is a problem that may have negative consequences on the biosphere. The levels of metals in all environments, including air, water and soil are increasing in some cases to toxic levels, with contributions from wide variety of industrial and domestic sources. Metal contaminated environments pose serious threat to health and ecosystems. The most abundant pollutants in waste water and in sewage are heavy metals (Hong et al., 1996).The environmental pollution by heavy metals comes from anthropogenic sources such as smelters, mining, power stations and the application of pesticides containing metal, fertilizer and sewage sludge and the irresponsible disposal of wastes by various industries (Meghraj et al.,2013) Some of the negative impacts of heavy metals on plants include decrease of seed germination and lipid content by cadmium, decreased enzyme activity and plant growth by chromium, the inhibition of photosynthesis by copper and mercury, the reduction of seed germination by nickel and the reduction of chlorophyll production and plant growth by lead (Gardea-Torresdey et al.,2005). The impacts on animals include reduced growth and development, cancer, organ damage, nervous system damage and in extreme cases, death. Heavy metals contaminate the drinking water reservoirs, fresh water habitats and can alter microbial communities. Chemical precipitation of heavy metals in water has been practiced as a prime method of treatment in industrial waters for many years. A combination of precipitation with other chemical treatment techniques, such as ion exchange has been reported to be effective in heavy metal removal in polluted waters (Akpor et al., 2010).Adsorption is a widely used method for the treatment of industrial wastewater containing color, heavy metals and other inorganic and organic impurities This method suffers from low adsorption capacity and in some cases complete removal is not possible and high cost of the adsorbent (Patel et al., 2010). Chemical oxidation is a process in which the waste materials from the industrial waste water are removed by the help of chemical oxidation by the use of various chemicals mainly hydrogen peroxide is widely used for this purpose as reported (Dias-Machado et al., 2006; Ksibi 2006). Phytoremediation is a remediation process that entails the use of plants to partially or substantially remediate selected substances in contaminated soil, sludge, sediment, groundwater, surface water and wastewater. It is also referred to as green remediation, botano-remediation, agro-remediation or vegetative remediation (Pivetz 2001). All these methods have some limitations and the common problems that are associated with these methods are expensive and can themselves produce other waste disposal problems, which have limited their industrial applications(DebayanDas 2012).Among the available treatment processes, the application of the biological
IntechOpen eBooks, 2023
The analysis of the variables, bacterial population, and oxidation-reduction potential (ORP) during the bioleaching of sulfide ores by a bacterial strain of Acidithiobacillus ferrooxidans, isolated from acid mine effluent, aims at the solubilization of copper and the liberation of the gold present in an ore containing more than 80% sulfides. It was studied at different pulp densities (1, 2, and 6%-W/V) and with a 9 k medium at different ferrous sulfate concentrations (0, 3, 6, 9, 12, and 15 g/L), keeping temperature and pH constant. The tests were carried out in three consecutive stages, starting with inoculum, whose cell content was 7.05x10 7 Cell/mL, then the strain with the highest population obtained in the previous stage was used, observing the variation in the periods of adaptation and growth. During the bioleaching of sulfide ores, in the first stage, the maximum bacterial population achieved was 4.75x10 7 Cell/mL in 24 days with 6 g/L ferrous sulfate, in the second stage, the maximum population was 6.30x10 7 Cell/mL without the addition of ferrous sulfate, and in the third stage, the bacterial population became 4.51x10 7 Cell/mL. The exponential characteristic growth of the population started at approximately 13, 8, and 3 days, respectively in each stage.