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A greener approach for resource recycling: Manganese bioleaching
... Investigation of these processes contributes to the understanding of biomineralization mechanisms under the influence of lithobiotic microbial community and biogeochemical cycles. These knowledge will create a basis for the potential biotechnological applications using fungi (Gadd 2010;Mulligan et al. 2004;Das et al. 2011Das et al. , 2015Das et al. , 2016Acharya et al. 2004). ...
... Manganese is a technologically important metal that has a few direct primary sources and is often mined in conjunction with other metals (Cu, Ni, and other), as well as from the low-grade manganese ores (Das et al. 2011(Das et al. , 2015Acharya et al. 2004;Ghosh et al., 2016). Genuine interest in biotechnologies using diverse microbes, which leach manganese and other metals from the ores including low-grade ores, lies in biomining which is a superior green alternative to the current pyro metallurgical techniques (Mehta et al. 2010, Pattnaik et al. 2019, Acharya et al., 2004, Huerta-Rosas et al, 2020, Ghosh et al., 2016, Mulligan et al., 2004. ...
... Manganese is a technologically important metal that has a few direct primary sources and is often mined in conjunction with other metals (Cu, Ni, and other), as well as from the low-grade manganese ores (Das et al. 2011(Das et al. , 2015Acharya et al. 2004;Ghosh et al., 2016). Genuine interest in biotechnologies using diverse microbes, which leach manganese and other metals from the ores including low-grade ores, lies in biomining which is a superior green alternative to the current pyro metallurgical techniques (Mehta et al. 2010, Pattnaik et al. 2019, Acharya et al., 2004, Huerta-Rosas et al, 2020, Ghosh et al., 2016, Mulligan et al., 2004. Microscopic fungi (micromycetes), which are active producers of various organic acids, are often used in bioleaching. ...
Microscopic fungi (micromycetes) play an important role in rock alteration, often leading to the formation of insoluble biogenic oxalates on their surface. Oxalate crystallization under the influence of fungus Aspergillus niger (one of the most active stone destructors) was studied in vitro conditions on following Mn,Ca-bearing minerals of manganese ores: todorokite (Na0.36,Ca0.09,K0.06,Sr0.03, Ba0.02)0.56(Mn5.53,Mg0.47)O12∙3–4H2O and kutnohorite (Ca0.77,Mn0.23)(Mn0.74,Fe0.14,Mg0.11)(CO3)2. The underlying minerals and the products of their alteration were investigated via powder and single-crystal X-ray diffraction, optical microscopy, SEM and EDX methods.
It was shown that more intense leaching of Ca-ions (compared to Mn-ions) from todorokite and kutnohorite leads to an earlier crystallization of calcium oxalates (predominantly whewellite) compared to manganese (lindbergite, falottaite). Crystallization of manganese oxalates on the surface of kutnohorite occurs in a more acidic (compared to todorokite) medium through the formation of mycogenic Mn,Ca-bearing oxides, which are close in composition and structure to todorokite. The possibility of structural evolution within the manganese oxalate crystalline phases caused by hydration and dehydration processes, which are responsible for changes in proportions of lindbergite and falottaite, derives from the similarities of falottaite and lindbergite crystal structures. The amorphization of falottaite in the temperature range of 70–80 °C suggests that formation of linbergite by falottaite dehydration occurs via amorphous precursor.
The result can be used for developing efficient biotechnologies using fungi for industrial enrichment of poor manganese ores and environmental bioremediation.
... Around 96% of the global Mn production occurs in 12 countries, including China, followed by India, Ukraine, South Africa, Norway, and the Republic of Korea. The global utilization of Mn is beyond 1,400,000 tons, which is estimated to rise several folds in the coming years (Ghosh et al. 2016;) (Figure 1). The utilization of Mn ore has increased significantly in the recent times due to rising of steel manufacture over the years. ...
... The confirmation of the Mn reductase existence in the outer layer of oxygen, which is essential for Mn reduction through microbes, has been done through cell fractionations experiments as carried out by Ehrlich (1993). MnO 2 reduction through bacteria needs direct interaction with the metal surface (Ghosh et al. 2016Haghshenas et al.2007 In the matter of this indirect mechanism, there is no direct connection in between microbes and minerals. ...
... There are so many physical and chemical parameters, which influence the bioleaching process such as different types of microbes, types of waste residues, many physiochemical characteristics, and different operating systems (Ghosh et al. , 2016. The conventional leaching bacterium belongs to the genus Acidithiobacillus that are usually Gram-negative proteobacteria . ...
Mineral resources have been counted as public assets with economic benefit since time immemor-ial. Due to the rising issue of decreasing mineral deposits, recovery of metals from several waste residues has become progressively more essential. Novel and efficient recycling processes have been on the rise globally. Manganese (Mn) as the fourth most industrially applicable metal generates an extensive quantity of metallic waste which not only leads to loss of precious metal but also results in environmental toxicity. Globally, around 7 million tons of high-grade ores are produced , whereas 8 million tons of Mn alloys are produced yearly. Therefore, it is of greater significance to recover and recycle Mn from various waste residues. Various physical and biological techniques have been developed for recycling Mn from waste residues. Traditional Mn extraction processes are costly and labor intensive in nature, on the contrary, bioleaching techniques using diverse microorganism's, form the basis of an efficient, eco-friendly, and economically sustainable process of metal recovery. The quick progress in current methodologies to counteract the fast consumption of innate mineral resources involves the proper utilization of unused waste residues containing industrially important metals like Mn. This review focuses to enumerate diverse features of Mn recovery, efficient methodologies, bioleaching of Mn, merits of Mn bioleaching, and applications of recycled Mn along with the futuristic applications. Manganese recovery by means of biol-eaching will play a major role in changing the present situation where innate assets are quickly diminishing and substitute for metal recovery methodologies are the demand of this time. ARTICLE HISTORY
... However, bacterial strains play a crucial role in Mn biogeochemical cycling due to the presence of inherent cellular mechanisms aiding in maintaining homeostasis across the ecosystem 5 . Microbial strains are known to possess enzymes like multi copper oxidase and manganese reductase 6 which can take up excess Mn from the environment and solubilise it in the cell before releasing it to the environment [7][8][9] . Some bacterial species such as Bacillus and Aerobacter, release strong chelating agents called "siderophores" into the surroundings which generally act as metal-capturing devise. ...
... In some cases, bacteria require direct contact with the ore constituents to solubilise the metals. Some strains also use enzymatic machinery to solubilise metals conjugated in the ore samples 8,30 . ...
... Enzymatic mechanisms in specific bacterial strains help them to scavenge this metal ion and associated elements, thereby playing a crucial role in biogeochemical cycles. Bacterial strains mostly carry out solubilisation through direct and enzymatic mechanism which involves direct contact of the ore surface with the bacteria and the enzymatic machinery within the bacterial strains 8,24 . Mn solubilising microbial strains are known to possess various metal solubilising enzymes like multi copper oxidase and manganese reductase (Fig. 14) 6,9 which can take up excess metal ions from the environment and solubilise it in the cell before releasing it to the environment 7,8,34,35 . ...
To extend the knowledge on the microbial diversity of manganese rich environments, we performed a clone library based study using metagenomic approach. Pyrosequencing based analysis of 16S rRNA genes were carried out on an Illumina platform to gain insights into the bacterial community inhabiting in a manganese mining site and the taxonomic profiles were correlated with the inherent capacities of these strains to solubilise manganese. The application of shot gun sequencing in this study yielded results which revealed the highest prevalence of Proteobacteria (42.47%), followed by Actinobacteria (23.99%) in the area of study. Cluster of orthologous group (COG) functional category has 85,066 predicted functions. Out of which 11% are involved in metabolism of amino acid, 9% are involved in production and conversion of energy while Keto Encyclopedia of Gene and Genomes (KEGG) functional category has 107,388 predicted functions, out of which 55% are involved in cellular metabolism, 15% are environmental and information processing and 12% are genetic information processing in nature. The isolated microbial consortia demonstrated visible growth in presence of high concentrations of Mn. Solubilisation studies resulted in 86% of manganese recovery after 20 days. The result presented in this study has important implications in understanding the microbial diversity in manganese contaminated mine tailings and their role in natural geochemical cycling of Mn.
... Chromium particles basically affects plants, animals, and aquatic species. In plants Chromium is up taken through carrier method in which sulfate ion plays a key role and magnesium ion is replaced by protons and this metal can affect both plants and animals (Ghosh et al. 2016;Ghosh and Das 2015;Mishra et al. 2019). Plants got degraded through wilting, chlorosis of new leaves, deformation of hairy root and destroys pigment-protein complex present in thylakoid membrane ; in some cases, there is decrease in plant growth, increases vacuole number, electron density get disturbed. ...
... Elemental chromium is mainly obtained in the form of chromite. Trivalent and hexavalent form of chromium is highly stable than other oxidation states and these are mainly present in industrial effluents from steel, tannery and chemical industry, metal tailing at the mining sites (Ghosh et al. 2016). Hexavalent chromium occurs mostly as chromate ions or chromic acid; these is highly soluble which can contaminate both ground water and surface water and, in some case, they can form colloid with the soil surface whereas trivalent chromium occur mostly as oxides, hydroxides, sulfates and they can form bond with solid surface which are usually stronger. ...
... The continuous loss of natural resources, increasing energy prices and tight environmental restrictions also lead to expanded metal recovery efforts (Ghosh et al., 2016;Shen et al., 2007;Xin et al., 2011). The development of a competent and cost-effective extractive method is now awaiting low-grade ores in millions of tons (Ghosh et al., 2016;Pradhan et al., 2006) (Arsent'ev et al., 1991). ...
... The continuous loss of natural resources, increasing energy prices and tight environmental restrictions also lead to expanded metal recovery efforts (Ghosh et al., 2016;Shen et al., 2007;Xin et al., 2011). The development of a competent and cost-effective extractive method is now awaiting low-grade ores in millions of tons (Ghosh et al., 2016;Pradhan et al., 2006) (Arsent'ev et al., 1991). High-grade manganese ore resources (>40%) are typically used to produce metallic alloys by pyrometallurgical processes as they are more readily available for this process (Aslan, 2007). ...
Using a software-based experiment design, the application of the leaching process for the extraction of manganese from Zinc Plant Slag (ZPS) was investigated. In this study, the effect of different parameters, i.e., H2SO4 concentration, pulp density, agitation rate, temperature and reaction time, was investigated. Response Surface Methodology (RSM) based on the Central Composite Design (CCD) has been implemented to consider the main parameters. A hydrometallurgical route to manganese silicate from spent zinc plant residue has been proposed in this investigation. Based on the investigation, Mn can be extracted from ZPS in sulfuric acid without any oxidant agents. The results showed that the optimum conditions of this study are an H2SO4 concentration of 2 mol/L and a solid/liquid ratio of 0.07 g/mL at 50°C for 150 min and an agitation speed of 1000 rpm. A manganese leaching efficiency higher than 83% is reached under these conditions, with a corresponding 22% iron, 23% lead, 68% zinc and 65% aluminum.
... Many studies have been conducted for recovery of manganese from EMS, including electrochemical (Shu et al., 2016b;Wang et al., 2016), concentrated acid extraction (Li et al., 2016b), ultrasonic extraction (Chandra et al., 2011), surfactant (Shu et al., 2020), water extraction (Ayala & Fernández, 2015;Zheng et al., 2020), and bio-leaching (Ghosh et al., 2016). Among those methods, the bio-leaching method has attracted more attentions due to its low energy consumption and low secondary pollution (Rao et al., 2010;Zhu et al., 2011). ...
... About 98% of Mn was extracted by Y1. The leaching efficiency of Mn from EMS was higher than the results of similar studies (Ghosh et al., 2016;Xin et al., 2011). ...
The related microbial metabolomics on biological recovery of manganese (Mn) from Electrolytic Manganese Slag (EMS) has not been studied. This study aimed at open the door to the metabolic characteristics of microorganisms in leaching Mn from EMS by using waste molasses (WM) as carbon source. Results show Microbacterium trichothecenolyticum Y1 (Y1) could effectively leach Mn from EMS in combination with using waste molasses as carbon and energy sources. For the first time, Y1 was identified to be capable of generating and then metabolizing several organic acids or other organic matter (e.g., fumaric acid, succinic acid, malic acid, glyoxylic acid, 3-hydroxybutyric acid, glutaric acid, L(+)-tartaric acid, citric acid, tetrahydrofolic acid, and L-methionine). The production of organic acids by Y1 bacteria was promoted by EMS with the carbon source. This study demonstrated for the first time that metabolic characteristics and carbon source metabolic pathways of Y1 in bioleaching of Mn from EMS.
... This is due to the ability of manganese solubilization by microorganisms and also due to the influence of the transitional compounds formed during solubilization (Das et al. 2011;Chen et al. 2011). Researchers showed that it is possible to mobilize metals from mining wastes which will serve a dual purpose of both resource recycling and environmental beneficiation (Mohapatra et al. 2007;Das et al. 2012;Ghosh et al. 2016;Mishra et al. 2019). There are recent reports on manganese biosolubilization in diverse group of microorganisms including Lysinibacillus sp. ...
... Due to extensive mining, mining wastes in the form of low-grade ores are present in millions of tones in this region which could be used as an alternative source of Mn. Figure 1 depicts the satellite image of Barbil District of Odisha obtained from Google (Maphill). The collected ore was crushed, grounded, and sieved for leaching experiments as per the protocols of Ghosh et al. 2016. The ore was grinded by the ball mill and sieved to get different size fractions using sieves of diameter > 4 mm, 4-1 mm, 1 mm-150 μm, and < 150 μm. ...
There has been alarming depletion of manganese (Mn) reserves owing to the ongoing extensive mining operations for catering the massive industrial demand of this element. Moreover, the mining operations have been leading to the generation of Mn-rich waste, thereby contaminating both terrestrial and aquatic bodies. The current scenario necessitates the development of alternative processes for bioremediation as well as economic recovery of Mn from mining wastes. The present investigation aims to report the bioleaching of Mn by Lysinibacillus sp. from mining waste residues in the context of mine waste remediation. Results confirmed that the native isolate had a high Mn biosolubilization potential with a solubilizing efficiency of 84% at the end of a 21-day study under optimized conditions of pulp density 2% (< 150-μm particle size), pH 6.5, and temperature 30 °C. Fourier transform infrared spectroscopy (FTIR) studies followed by liquid chromatography mass spectrometry (LC-MS) analysis were used to ascertain the change in microbial protein conformation, configuration, and protein identification. The results revealed the expression of heat shock proteins (HSP) from the family HSP which is predominantly expressed in bacteria during stress conditions. This study represents the application of native bacterial strain in Mn biosolubilization. We foresee the utility of proteomics-based studies to provide a methodological framework to the underlying mechanism of metal solubilization, thereby facilitating the two-tier benefit of recovery of Mn from alternative sources as well as bioremediation of waste having high manganese content.
... While trace amounts of Cd in the environment are byproducts of these processes, the majority of environmental Cd is the result of industrial and agricultural usage (Bjørklund, et al., 2020). Soluble Cd ions from phosphate fertilizers can contaminate water and soil and subsequently accumulate in aquatic organisms or plants such as tobacco, grains, and root vegetables (Ghosh, et al., 2016). Because of accumulation in tobacco plants, individuals who smoke are exposed to significant levels of Cd through the inhalation of cigarette smoke. ...
Industrial activities in combination with the anthropogenesis of humans on the planet are the leading cause of heavy metal pollutants. The unabated continued loading of an ecosystem with these metallic contaminants has incidentally led to environmental degradation and human health complications. The study sort to review in clear terms how these heavy metals have caused damage to nature and reduce quality of life. We reported that the majority of these pollutants are emitted by mining activities and tag Lead (Pb), Arsenic (As), Mercury (Hg), Cadmium (Cd) and Chromium (Cr) as priority metallic pollutants which significantly impact negatively human health while causing ecological deterioration. Also, it was recorded that these metallic pollutants constituted components of agricultural inputs which at even in small concentrations, due to their tenacity, non-degradability, biological toxicity, and capacity to enter the food chain. Another critical environmental problem in recent years is soil pollution caused by excessive use of inorganic fertilizers. It was investigated that when these metallic ions upon entering into food chain via contaminated soils and water, reaching critical concentrations, causing harmful metabolites in the body, and having adverse effects on living organisms such as kidney damage, hypertension, mutagenicity, carcinogenesis, diabetes, liver disease, cardiovascular disease, and various types of cancer are some ramifications caused by exposure to high contents of Arsenic (As) element. Chromium (Cr) had been identified as carcinogenic to humans capable of causing liver necrosis, nephritis, and death. Lead in the human system pose a threat to the tree-sensitive organs of the hematopoietic.
... However, the bacterial strains at first need to be exposed to the pollutants for activation of enzymatic processes for bioremediation. For bacterial species like Desulfovibrio, Pseudomonas, Geobacterand Bacillus, there is a minimum necessity of pollutant concentration for initiating enzymatic bioremediation processes (Adenipekun and Lawal 2012; Ghosh et al. 2016). ...
The increase in population has resulted in a rapid increase in waste that is being dumped within the environment. The addition of various harmful and contaminating compounds results in the degradation of the environment and has a direct impact on human health. Various research studies that are taking place in recent times help in the enhancement of the naturally available microbes to degrade toxic compounds that are liberated into the environment. Although various types of bioremediation techniques are available, microbe-associated remediation is proven to be the best option due to its effectiveness, no generation of toxic by-products, and natural availability of microbes with the ability to take up nutrients from the toxic contaminants that exist on the surface of the earth. Both ex situ and in situ bioremediation can be accomplished with the help of these microbes. In most cases, this is done through biofilm-assisted seclusion of pollutants, more precisely by means of extracellular polymeric substances (EPSs) of biofilm matrix. In recent times, various types of techniques have been implemented like proteomics, genomics, fluxomics and transcriptomics for bringing about maximum remediation by the microbial species. In order to explore the different kinds of microbial communities involved in natural bioremediation, the strategic approach of metagenomic analysis is adopted, which has brought about a technological drift in remediation, even at a genomic level. As chemical mode of remediating wastes are associated with the release of various harmful chemicals those can be toxic to the environment, the use of biological systems can be a potential agent in the conversion of complex waste materials to simpler substances so that it mixes with the environment in easier manner. Microbes are the potential entities that can easily act on the waste materials and bring about remediation in an effective manner.
... Recently, many researchers have investigated siliconactivated bioleaching techniques, such as the treatment of magnesite, bauxite, nickel-bearing feedstock, and pyrolusite by silicate bacteria (Chaerun et al. 2017, Ghosh et al. 2016, Lian et al. 2008, Lv et al. 2021, Lv et al. 2020, Bhatti 2009, Srichandan et al. 2019. ...
In China, a large amount of soil lack available silicon, which leads to a decrease in crop yield. Furthermore, the solid waste coal tailings contain abundant minerals that are rich in silicon, which have not been fully utilized. In this work, we used Bacillus mucilaginosus as the leaching agent to convert insoluble silicon in coal tailings into available silicon for crop. After single-factor experiments, the optimal leaching conditions with bacterial dosage, coal tailings weight, initial pH, leaching temperature, and shaking speed were obtained. Kinetic analysis showed that the controlling process of the leaching was a chemical reaction. The leaching process was characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectrometer (FT-IR), and high-performance liquid chromatography (HPLC). The results showed that bioleaching is a feasible and efficient method to extract silicon from coal tailings, with a maximum leaching amount of 260 mg L⁻¹ after 16 days, which occupied 93% of the total effective silicon. In conclusion, this work demonstrates that bioleaching technology can effectively solve the problem of the environmental utilization of coal tailings by converting them into a soil improver that can provide beneficial nutrients for crop growth.
... Several types of microorganisms had been reported to possess the potential of biotransformation of E-waste. It can be easily recognized that various microorganisms adopt separate mechanisms for E-waste bioleaching [52]. ...
Pollution by end-of-life electronics is a rapid ever-increasing threat and is a universal concern with production of million metric tons of these wastes per annum. Electronic wastes (E-waste) are rejected electric or electronic equipment which have no other applications. The aggrandized unproper land filling of E-waste may generate hazardous effects on living organisms and ecosystem. At present, millions of tons of E-waste await the advancement of more efficient and worthwhile recycling techniques. Recovery of base and critical elements from electronic scraps will not only reduce the mining of these elements from natural resources but also reduces the contamination caused by the hazardous chemicals (mostly organic micropollutants) released from these wastes when unproperly disposed of. Bioleaching is reported to be the most eco-friendly process for metal recycling from spent electronic goods. A detailed investigation of microbial biodiversity and a molecular understanding of the metabolic pathways of bioleaching microorganisms will play a vital function in extraction of valuable minerals from the end-of-life scraps. Bioleaching technique as an economic and green technology costs around 7 USD per kg for effective reusing of E-waste as compared to other physical and chemical techniques. This review provides a summary of worldwide scenario of electronic pollutants; generation, composition and hazardous components of electronic waste; recycling of valuable elements through bioleaching; mechanism of bioleaching; microorganisms involved in base and critical element recovery from E-waste; commercial bioleaching operations; and upcoming aspects of this eco-friendly technique.
... Manganese, a heavy metal, is abundant in nature and also plays a significant role in many important industries [1,2]. However, due to factors such as artificial mining of mineral resources, illegal discharge of pollutants from factories, and dissolution of manganese minerals in aquifers caused by changes in ecological environment, the problem of pollution has become increasingly prominent [3][4][5]. In recent years, the concentration of manganese in underground wells in many countries has far exceeded the standards of the World Health Organization [6][7][8][9].Overexposure to manganese can cause a variety of negative health effects for humans [10,11], and high manganese content in plants will lead to crop necrosis and cotton wrinkling, thus affecting the food and textile industry [12]. ...
Multiwalled carbon nanotubes (MWCNTs) were modified by oxidation and acidification with concentrated HNO3 and H2SO4, and the modified multiwalled carbon nanotubes (M-MWCNTs) and raw MWCNTs were characterized by several analytical techniques. Then the demanganization effects of MWCNTs and M-MWCNTs were well investigated and elucidated. The experimental data demonstrated that the adsorption efficiency of Mn(II) could be greatly promoted by M-MWCNTs from about 20% to 75%, and the optimal adsorption time was 6 h and the optimal pH was 6. The results of the kinetic model studies showed that Mn(II) removal by M-MWCNTs followed the pseudo-second-order model. Isothermal studies were conducted and the results demonstrated that the experimental data fitted well with the three models. The reliability of the experimental results was well verified by PSO–BP simulation, and the present conclusion could be used as a condition for further simulation. The research results provide a potential technology for promoting the removal of manganese from wastewater; at the same time, the application of various mathematical models also provides more scientific ideas for the research of the mechanism of adsorption of heavy metals by nanomaterials.
... At present fresh water sources are polluted from various sources which includes, industries, municipal pollutants, biomedical contaminants and other anthropogenic activities (Das and Ghosh, 2022;Ghosh et al., 2016Das, 2016). These pollutants deliver severe adverse impact on the environment and the inhabitants (Bal, 2017;Sadasivuni et al., 2019). ...
Synthetic microfibers are universally recognized as an emerging pollutant in all ecosystems. The present investigation focuses on the evaluation and quantification of synthetic microfiber released from domestic laundering wastewater from different regions of Bhubaneswar city of Odisha state of India. The estimated number of microfibers collected from 500 ml of sample varied from 200 to 500 in numbers with an average amount of biomass in the range of 0.4-4 g. The surface morphology of the samples was assessed by Scanning Electron Microscopic analysis which revealed that the fibers were having a length of approximately 10-30 mm and diameter of 10-20 μm. Carbonyl (C-O) stretching band at 1711 cm − 1 and Aldehyde (-C-H) Weak bond at 2917.38 cm − 1 absorption were recorded from Fourier transform infrared spectroscopic analysis. As microfibers released from synthetic apparels are major source of environmental microplastic pollution their precise detection could help in controlling this problem.
... These pollutants have emerged as potential threats to not only the ecosystem but also for human being (Das et al. 2015a;Mishra et al. 2022). Industrial waste containing diverse heavy metals eventually get accumulated in the soil as they are released out from the dumping sites where these metal containing wastes are indiscriminately dumped (Das and Mishra 2008;Das et al. 2011a;Mishra et al. 2021b;Ghosh et al., 2016). These metallic pollutants get absorbed by the trees growing in such soils, get biomagnified as a part of the food chain, eventually reaching the human body and causing serious harm. ...
... Now, there have been reports on some representative processing methods, such as reduction roasting-ammonia leaching, 11 cuprous ion catalytic reduction-ammoniacal leaching, 12 reduction acid leaching in H 2 SO 4 or HCl system, 13,14 rusting-leaching process, 15 and bioleaching. 16 A critical review of the literature, especially in terms of energy consumption, carbon emission, and selective extraction, indicates that the reductive leaching of manganese nodules in the sulphuric acid system is a relatively promising and inexpensive approach. ...
The effect of Fe3+ ions on the ocean manganese nodule reductive leaching in imitated sulphuric acid solutions was investigated. This work is presented in two courses, including the influence of Fe3+ ions on valuable metal extraction and the electrochemical reductive dissolution of manganese nodules. The results show that the beneficial effects of Fe3+ ion can be interpreted based on two aspects: the first is the acceleration caused by the active transformation of Fe3+/Fe2+ pair, and the second is the hydrogen ion buffer action generated by Fe3+ ion hydrolysis on the surface. On one side, Fe3+ ion could lessen the hydrogen consumption happening at the interface layer of the nodule supported by the leaching test and cyclic voltammetry results. On the other side, Fe3+ ions could be converted into Fe2+ ions and then preferentially reduce manganese oxide leading to an acceleration of the charge transfer reaction of the manganese nodule based on cyclic voltammetry, polarization, and impedance analysis results. The reduction leaching of manganese nodules in sulphuric acid solution is mainly controlled by the electrochemical interface reduction corresponding to manganese oxide dissolution, and the active conversion of the Fe3+/Fe2+ couple affects the dissolution of high valence manganese oxide.
... The chemical and substantial properties of microplastics such as thickness, molecular mass, crystallinity, functional groups as well as plasticizers may play an important role in their degradation process. Environmental factors like light, heat, temperature, humidity and the presence of chemicals also affect microplastics degradation (Ghosh et al. 2016;Amaral-Zettler et al. 2020;Kumar and Das 2017). The impact of a specific ecological factor on the degradation rate is highly dependent on the form of microplastics. ...
A major apprehension is over microplastic pollution in the aquatic environment. These microplastics particles represent a novel medium in the aquatic environment, providing a substratum for various organic contaminants and for colonization of microorganisms. Microorganisms form a biofilm on the exterior of pollutants, consequential in a region known as a plastisphere, in which they interrelate and generate acid and different enzymes for microplastic degradation. The use of microbes for microplastic degradation has become a contentious exit indication as society focuses more on environmentally friendly pollution reduction methods. After both substantial and elemental degradation, biodegradation occurs, weakening the arrangement of polymers. Natural resource microbes have a significant effect on the reduction of plastic waste in the environment. The current review article discusses microbial colonization and degradation of microplastics present in aquatic ecosystems and the processes involved. While studying and considering how these microplastic particles have now turn out to be a recent environmental position within various aquatic environments, we emphasized the significance of colonization and microbial-assisted degradation of aquatic microplastics in this article.
... Manganese is very used in the steel production (Ghosh et al. 2016), and the high concentration in this area can be related to the industrial activities nearby, as the biggest steel industry of Latin America is located at this region. Manganese is considered an essential micronutrient for the metabolic route in plants. ...
In this study, we analyzed toxic metals in leaves and marine sediment samples from the black mangrove in Sepetiba Bay to measure contamination and the use of Avicennia schaueriana leaves as bioindicator of toxic metal environmental pollution. The concentrations of heavy metals, namely cadmium (Cd), chrome (Cr), cobalt (Co), copper (Cu), lead (Pb), manganese (Mn), molybdenum (Mo), and zinc (Zn), were determined by using inductively coupled plasma optical emission spectrometry (ICP-OES). High concentrations of Mn were found in the leaves, while high concentrations of Mo and Zn were found in sediments. A. schaueriana leaves showed a tremendous capacity to absorb toxic metals, tolerating high concentration of manganese and may be used as phytoremediator for this toxic metal in impacted coastal marine environments. Herein, we reported for the first time the utilization of Avicennia schaueriana as a highly efficient accumulator for Mn.
... The replacement of conventional processes, such as pyrometallurgy and hydrometallurgy, by large-scale environmentally friendly processes has been increasing Steinmann et al. 2014) worldwide, which is related to the concept of green chemistry (Brierley and Brierley 2001;Ghosh et al. 2016;Mani and Kumar 2014). An alternative is a biological process known as biomining, which is a generic term used to describe the extraction and recovery of metals presents in ores or wastes by biological systems (mostly prokaryotic microorganisms) (Johnson 2014). ...
Mineral coal is one of the most employed natural resources that represent potential environmental issues. The mine tailing contains several valuable minerals such as zinc, molybdenum, vanadium, chromium, iron, and copper. Currently, the most part of mine tailings is disposed at large tailing ponds. Another important tailing from mineral coal is fly ash, the main residue from thermoelectric plants, which may also contain valuable minerals. Currently, the most part of coal fly ash produced is used as raw material for cement fabrication or disposed at ash ponds. In this sense, biomining and bioleaching is an economically and environmentally attractive technology that can be used for metal recovery from residues such as mine tailing and coal ash, in line up with the concept of green chemistry. There are sparse data available on bioleaching of coal ash using either autotrophic or heterotrophic microorganisms. Therefore, the aim of this chapter was to describe the key aspects related to biomining and bioleaching of mine tailing and coal ash, pointing out the state of the art and some future perspectives.
... In this case, cell adhesion to the mineral surface is an absolute essential prerequisite. The indirect mechanism is mainly based on the production of metabolites like organic acid which in turn causes metal solubilization Das, Swain, Panda, Pradhan, & Sukla, 2012;Ghosh, Mohanty, Akcil, Sukla, & Das, 2016). ...
The rapid decrease of natural resources and generation of huge amount of metallic wastes from mining industries has led to the focus of researchers to shift to alternative methods of waste benefaction and resource recycling. This study aims at the development of an eco friendly technique to recover Manganese (Mn) from mining waste residues using Acinetobacter sp. Bioleaching experiments were conducted in shake flasks at initial pH 6.5, 5% w/v inoculums and 2% pulp density at 30 °C with agitation speed 200 RPM and Acinetobacter sp. as inoculum. Mn recovery of 76% was recorded in 20 days. The analysis of the changes in cellular protein expression and conformation was carried out through sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS PAGE) and fourier transform infrared spectroscopy. The results reveal that bioleaching can alter protein expression and also result in conformational changes in protein structure. The present study sheds light on the greener alternative to recover and recycle manganese from wastes native bacteria. Exciting prospects for the utilization of mining wastes are in store in the near future; providing an economic and ecologically sound alternative to pyrometallurgical processes.
... The enzymatic reduction of manganese occurs in the form of respiration. In the direct mechanism, the bacteria uses MnO 2 as a final electron acceptor for cellular respiration instead of oxygen in an electron transport chain and causes the release of Mn 2þ into the medium (Ghosh et al., 2016). ...
... Soil is the most fundamental resource of the terrestrial ecosystem which is facing strong pollution heaviness from different anthropogenic activities Mishra, 2008, 2010;Ghosh et al., 2016). Terrestrial environment is considered as the main source of this microfiber fiber pollution with over 400 Mts of plastic production globally each year (Qualman, 2017). ...
The ever-increasing use of domestic washing machine by urban population is playing a major role in synthetic microfibers (SMFs) pollution via entering the ecosystem. Although many of the sources of fragmented plastic pollution in oceanic environments have been well known, urban areas are playing a major contributor due to huge populations. Thousands of scientific investigations are now reporting the adverse effect of these micro pollutants on aquatic and terrestrial environment, food chain and human health. Microfiber particles along with washing machine grey waters are emitted into urban drainage adjoining the lakes and river which ultimately mix in ocean water and after emission these tiny particles dispersed though out the ocean water by currents due to their low density. Environmental pollution cause by domestic laundering processes of synthetic clothes has been reported as the major cause of primary microplastics in the marine system. While community awareness and improved education will be successful in making public conscious of this problem, there needs to be more research on global scale to mitigate the ecological consequences of microfiber pollution by urban habitats through environmental friendly approach. This paper focuses to improve the understanding of urban population influence on microfiber pollution, their ecological toxicity to aquatic organism and humans, detection and characterization techniques with an emphasis on future research for prevention and control of microfiber pollution.
... The inclusion of metal bioavailability as a freshwater quality component has been recommended in mining-impacted rivers as a more precise indication of mining pollution, preventing the underestimation of metal concentrations in pH-buffered rivers [56]. Moreover, besides the fact that pH and microbial enzymes influence metal solubility in freshwaters [57], the site-specific physicochemical environment (e.g., the presence of dissolved organic carbon or cationic stress) enhances the ecotoxicity of low zinc concentrations [55]. Metal phase distribution is also affected by pH variations, inducing metal precipitation or affinity to a matrix [56]. ...
Water quality assessments provide essential information for protecting aquatic habitats and stakeholders downstream of mining sites. Moreover, mining companies must comply with environmental quality standards and include public participation in water quality monitoring (WQM) practices. However, overarching challenges beyond corporate environmental responsibility are the scientific soundness, political relevance and harmonization of WQM practices. In this study, a mountainous watershed supporting large-scale gold mining in the headwaters, besides urban and agricultural landuses at lower altitudes, is assessed in the dry season. Conventional physicochemical and biological (Biological Monitoring Water Party-Colombia index) freshwater quality parameters were evaluated, including hydromorphological and land-use characteristics. According to the indicators used, water quality deterioration by mining was absent, in contrast to the effects of urban economic activities, hydromorphological alterations and (less important) agricultural pollutants. We argue that mining impacts are hardly captured due to the limited ecological knowledge of high-mountain freshwaters, including uncharacterized mining-specific bioindicators, environmental baselines and groundwater processes, as well as ecotoxicological and microbial freshwater quality components. Lessons for overcoming scientific and operational challenges are drawn from joint efforts among governments, academia and green economy competitiveness. Facing a rapid development of extractive industries, interinstitutional and multidisciplinary collaborations are urgently needed to implement more integrated freshwater quality indicators of complex mining impacts.
... The other group of microorganisms, such as sulfur-oxidizing bacteria also has capabilities for extracting metals from their deposits. This group consists of the genus Acidithiobacillus, Acidiphilium, Acidiphilum, Sulfobacillus and Sulfolobus (Ghosh et al. 2016;Jang and Valix 2017;Jalali et al. 2019;Huynh et al. 2019;Retnaningrum and Wilopo 2019). Whereas, heterotrophic bacteria such as Leptospirillum ferriphilum, Pseudomonas sp., Bacillus sp., and Acinetobacter sp were also reported to be capable of solubilizing metals (Ghost and Das 2017;Thavamani et al. 2017;Wang et al. 2018;Dong et al. 2019;Saleh et al. 2019). ...
Prasidya DA, Wilopo W, Warmada IW, Retnaningrum E. 2019. Optimization of manganese bioleaching activity and molecular characterization of indigenous heterotrophic bacteria isolated from the sulfuric area. Biodiversitas 20: 1904-1909. The present research evaluated the manganese bioleaching potency of a heterotrophic bacteria KB3B1. This bacterial strain has been isolated from sulfuric area located at Ungaran, Middle of Java, Indonesia using modified 9K medium by adding of several organic nutrients. The manganese bioleaching activities of the strain was analysed by applying of varying glycine concentrations (0, 5, 10, 15 mg mL-1) with pyrolusite pulp densities of 0.02 g cm-3 on a rotary shaker at 180 rpm for 18 days incubation. Several parameters, including the growth of bacteria, pH values, the concentration of soluble manganese and cyanide, were investigated at the interval of 3 days. Molecular characteristics of the strain were further analyzed based on 16S rDNA gene sequences. After 15 days, the maximum yield of manganese 16.6% was achieved under the addition of 10 mg mL-1 glycine. This maximum extract obtained was followed by the maximum bacterial growth, pH, and cyanide product of the strain. Phylogenetic analysis showed that the strain was closely related with Bacillus niacini EP89. Besides, the average frequencies of guanine and cytosine (G+C) of the strain was in same range as that of the reference bacteria in the GenBank and Bergey's Manual Systematics of Bacteria.
... In recent years, for extracting that manganese metal from the ore, bioleaching is an innovative biological treatment to be applied in industrial scale. Compared to the traditional mining procedures, it does not need high energy and does not produce toxic pollutants [3][4][5][6][7]. The reserve of manganese metal located at Kliripan, Kulon Progo, Yogyakarta, Indonesia is found in its oxide form as pyrolusite. ...
The manganese bioleaching process of pyrolusite from Kliripan, Indonesia using Acidithiobacillus sp KL3 was investigated. The influence pulp densities of pyrolusite (0.01, 0.02, 0.03 and 0.05 g/cm3) on the bioleaching processes were studied for 16 days. The reduction on pH values, the increasing of oxidation-reduction potential (ORP), sulfate and manganese concentration were analyzed. The manganese bioleaching mechanism of pyrolusite by the strain was monitored using Scanning Electron Microscope-Energy Dispersive-X-ray Spectroscopy (SEM-EDX). The results indicated that 0.02 g/cm3 of pyrolusite was considered to be the optimal pulp density for manganese bioleaching process. During this process, pH values decreased, furthermore resulted in increasing of ORP, the concentration of sulfate and manganese. SEM-EDX analysis clearly showed the evidence of directly bacterial cell attachment into the surface of pyrolusite. Extracellular polymeric substances (EPSs) were further founded on that surface. Sulfur elemental was oxidized by the strain which was then confirmed of resulting in solubilized manganese.
... Biological leaching (bioleaching) is a promising and novel method to extract or activate elements from ores or concentrates, has advantages of simplicity, low cost and environmental friendliness compared to traditional physical and chemical metallurgy processes, while the disadvantage of low leaching rate (Liu et al., 2012;Ghosh et al., 2016). In recent years, studies have found that silicate bacteria have the characteristics of dissolved phosphorus, potassium, nitrogen fixation and effective silicon leaching, which can be used for the leaching of silicate minerals (Siti et al., 2017;Akinci and Guven, 2011;Xin et al., 2011). ...
Electrolytic manganese residue (EMR)is a kind of solid waste generated along with the production of electrolytic manganese, with a high content of quartz and metals. The former can be used as silicon fertilizer for crops after activation, while the latter may cause harm to surrounding environment due to their toxicity. The aim of this study was to investigate the effects of bacterial on the activation of silicon and fixation of heavy metals in EMR by using microbe-mineral direct contact and indirect contact methods. Mixed cultures of Bacillus mucilaginosus (BM)and Bacillus circulans (BC)were used to achieve activation of silicon in EMR, and the leaching concentration of Mn, Co and Ni and their chemical forms in the leaching residue were also investigated. The results show that the microbe-mineral direct contact method has better performance for the activation of silicon in EMR with the available silicon in the leaching solution up to 163.27 mg L ⁻¹ than the indirect contact method. The metals (Mn, Co and Ni)remaining in the residue mainly exist as the stable state after bioleaching, with lower leaching concentration after bioleaching of 20 d. And the effect of silicon bacteria on activation of silicon and the fixation mechanism of metals including the effect of silicate and silicate bacteria is confirmed, and it is verified by the identification of metabolites and the analysis of chemical reaction process. This study investigates the treatment of EMR by using mixed silicate bacteria, and reveals the mechanisms of bacteria on the activation of silicon and fixaion of heavy metals in EMR. The bioleaching method not only provides silicon source for soil but also can realize the reclamation of EMR.
... Marine pollution due to synthetic microfibers and other anthropogenic sources is a serious matter of concern and significant treatment technologies for the removal of these pollutants are of immense importance (Das and Mishra, 2008;Ghosh et al., 2016;Das and Mishra, 2010). Removal of microfibers from contaminated water sources using current technologies is prohibitively expensive due to high capital expenditure and operating expenses. ...
... The enzymatic reduction of manganese occurs in the form of respiration. In the direct mechanism, the bacteria uses MnO 2 as a final electron acceptor for cellular respiration instead of oxygen in an electron transport chain and causes the release of Mn 2þ into the medium (Ghosh et al., 2016). ...
Spent coin cells are considered to be dangerous materials for the environment and human health due to their toxic compounds and their long half-lives. The present study investigated the bioleaching of lithium, cobalt, and manganese from spent coin cells using Acidithiobacillus ferrooxidans at different S/L ratios. It is shown that the S/L ratio of 40 g/L could be an optimal pulp density due to its high metal recovery and economic aspects. At an S/L ratio of 40 g/L, recovery rates of 100%, 88%, and 20% were achieved for lithium, cobalt, and manganese respectively. The results of structural analyses of the spent coin cells powder prior to and after bioleaching corroborated the bacterial activity effectiveness for metals mobilization from spent coin cells. The shrinking core model was employed to specify the rate-controlling step, which suggests that the diffusion of ferric ions plays a significant role in metals mobilization. A blank test was also performed and the results of it and bioleaching were compared; the results denoted the effectiveness of bioleaching.
... Marine pollution due to synthetic microfibers and other anthropogenic sources is a serious matter of concern and significant treatment technologies for the removal of these pollutants are of immense importance (Das and Mishra, 2008;Ghosh et al., 2016;Das and Mishra, 2010). Removal of microfibers from contaminated water sources using current technologies is prohibitively expensive due to high capital expenditure and operating expenses. ...
Microfibers are emerging pollutants with widespread distribution in the environment and have adverse ecological impacts. Approximately 2 million tonnes of microfibers are released into the ocean every year from various sources, of which 700,000 micro fleeces are released from each garment through domestic laundry. Microfibers are the major marine pollutant throughout the world estimating 13 million tonnes of coastal synthetic fabric waste entering the ocean each year, out of which 2.5 million tonnes enter through adjoining rivers. It is anticipated that, to date, 1.5 million trillion of microfibers are present in the ocean. Microfibers are mistakenly ingested by marine animals and cause hazardous effects to aquatic species. Microfiber treatment techniques are under progress for efficient control of this pollutant. This article focuses on global microfiber generation and its sources, pathway of its entry into the environment and food chain, potential threat to aquatic animals and humans, present treatment technologies, and future challenges.
... ferrooxidans) is by far the most widely used bioleaching microorganisms in ore leaching, including for Ni, Cu, Au, V, and Mn ores [7][8][9]. Additionally, a corrosion cell is the most common method in manganese oxide minerals and sulfide minerals for extracting valuable metals [10]. Many previous research studies have focused on the pyrite-pyrolusite coupled bio-leaching system. ...
Efficient extraction of Ni, Co, Cu, and Mn from low-grade and refractory ores is a common technical challenge. The present study proposes an Acidithiobacillus ferrooxidans-coupled leaching of Ni, Cu, Co, and Mn from oceanic polymetallic nodules and low-grade nickel sulfide ore, and focuses on the electrochemical behavior of the ores in simulated bio-leaching solutions. In the dissolution of polymetallic nodules, A. ferrooxidans facilitates the diffusion of H+ and accelerates electron transfer, producing a decrease in charge transfer resistance and promoting the Mn(IV)-preceding reaction. The use of A. ferrooxidans is beneficial for lower impedance of sulfur-nickel ore, faster diffusion rate of product layer, and better transformation of the Fe3+/Fe2+ couple and S0/S2− couple. A. ferrooxidans increases the potential difference between the nodule cathode and sulfide anode, and increases electron liberation from the sulfide ore. This motivates a significant increase in the average extraction rates of Ni, Co, Cu, and Mn in the bacterial solution. The bio-leaching efficiencies of Ni, Co, Cu, and Mn were as high as 95.4%, 97.8%, 92.2% and 97.3%, respectively, representing improvements of 17.1%, 11.5%, 14.3% and 12.9% relative to that of the germ- and Fe(III)-free acidic 9 K basic system.
... Bioreactor based bioleaching operations (Jungles et al. 2014;Zhou et al. 2009) such as compost bioreactors (Aerobic wetlands), stirred tank reactor (STR), continuous flow stirred tank reactors (CSTR), batch bioreactor for manganese recovery are presented in detail in the ( Table 3). The driving parameters of manganese biorecovery such as the biological factors, the microbial community involved and the diverse mechanism have been reviewed by Ghosh et al. (2016). Chemical solubilisation methods of Mn lead to the introduction of hazardous pollutants into the environment. ...
... Bioreactor based bioleaching operations (Jungles et al. 2014;Zhou et al. 2009) such as compost bioreactors (Aerobic wetlands), stirred tank reactor (STR), continuous flow stirred tank reactors (CSTR), batch bioreactor for manganese recovery are presented in detail in the ( Table 3). The driving parameters of manganese biorecovery such as the biological factors, the microbial community involved and the diverse mechanism have been reviewed by Ghosh et al. (2016). Chemical solubilisation methods of Mn lead to the introduction of hazardous pollutants into the environment. ...
The global consumption of manganese is rising due to its growing industrial requirement while the natural reserves of manganese are diminishing at an alarming rate. Consequently, recovery of manganese from metal containing wastes has become highly crucial. Bioleaching of metal from wastes using microbes provides an adequate advantage over the traditional method of recovery. A molecular level understanding of microbial catalyzed manganese recovery is essential for the exploitation of novel microorganisms for similar applications. In current scenario, the application of bioleaching concentrates on cost effective and eco-friendly recovery of precious metals from mining and industrial wastes. This review encompasses the modern improvements in biomining, highlights the comprehensive factors that emphasize the selection of manganese recovery technique, shed insights into spectacular progress in developing molecular based technologies and also identifies the applicability of different models in metal bioremediation which will not only aid in pollution abatement but also in the prevention of occupational health disorder.
... Over the years, bioleaching technology, which has been applied to copper, uranium, coal, nickel, and manganese mining [41][42][43], has progressed considerably, especially in Chile, South Africa, the United States, Australia, India, Mexico, Iran, and China. In 1762, in the Rio Tinto Mine of Spain, Copper (Cu) was leached from pyrite mixed with copper by acid mine drainage (AMD). ...
The commercial application of copper bioleaching, an environmentally-friendly approach for low-grade and secondary mineral resources recycling, has increased worldwide since the 2000s. As the world's second-largest economic entity and the largest developing country, China has the largest demand for metal resources, significantly advancing the theory and industrial technology of copper bioleaching. This paper reviews the exploration and application of copper bioleaching in China. Two typical bioleaching applications and technological processes, bioheap leaching at the Zijinshan Copper Mine and bioheap leaching at the Dexing Copper Mine, are introduced. The considerable research completed by researchers is summarized, especially focusing on the isolation and identification of leaching bacteria, the bioleaching mechanism and interface reactions, multistage percolation behavior, bioleaching system reconstruction, the multiphysics coupled model, and enhanced copper bioleaching from waste printed circuit boards (WPCBs). Based on this investigation in China, key trends and prospects in copper bioleaching-such as efficiency improvement, environmental protection, and improved technology applications-are proposed.
The potential to subsidize the development of areas furnished with ores is essential for producing supplies, services, and infrastructure that get a better social life quality. Bauxite mining is the foremost open-cast mining and bauxite is the only material for manufacturing aluminum metals and is used as a prominent industrial raw material. Demand for bauxite has grown enormously because of increased population and economic growth as it is required for the production of many other metals. A huge amount of bauxite residues are produced during aluminum production from bauxite ore which tremendously influences the environment and public health. Production of waste residues from bauxite ore leads to diminishing soil productivity and influences farming food yields. Soil and water are also contaminated by the addition of heavy metals, iron oxide, and aluminum hydroxide, which can prejudice public health. Microorganisms degrade and detoxify the pollutants into a nontoxic organic form that is helpful to the environment. Bioremediation has been a promising method to remove contaminants by using microorganisms. This enables the adsorption, accumulation, degradation, and utilization of emerging contaminants as nutrient resources by microbial communities for their sustenance. Sustainable management of bauxite mining and recovery of metals from wastes are mainly indispensable in this high time. This review article evaluates the effect of bauxite waste residues on the environment and its consequences on human health; it also emphasizes the biological remediation strategy for the remediation of contaminated mining areas and focuses on the sustainable management of bauxite waste residues.
The release of petroleum and petroleum derivatives, such as polycyclic aromatic hydrocarbons (PAHs), in the environment owing to anthropogenic activities, has become a major global threat to human health and ecological equilibrium. It causes a number of diseases and petroleum hydrocarbon (PH) compounds bind to soil components, making their removal very difficult. In order to find an eco-friendly, convenient, and non-expensive way, indigenous PH degrading microorganisms are employed. Biofilm, being a syntrophic association plays an important role in PAH degradation. The three-dimensional structure of the biofilm matrix is found to facilitate the efficient and rapid degradation of PAH. Various physicochemical parameters of biofilm are found to regulate the efficacy of PAH degradation. In order to amend certain drawbacks of biofilm mediated remedi-ation, these days microbial electrochemical systems are increasingly being used for redressal of PH contamination, where the solid anode functions as an endless electron acceptor and the microbial activity is stimulated by bio-current in situ to guarantee the PH removal from contaminated soil and water. Following uptake of emulsified PH, it may be denatured by biofilm-associated enzymes or by biosurfactant molecules (such as rhamnolipids). The biomolecules synthesized by the bacterial cells further help in the expression of the specific genes thereby helping in the enhancement of PH degradation. ARTICLE HISTORY
A mature technology of lithium-ion batteries (LIBs) is applied in various electronic devices. The wide application of LIBs has brought large quantities of spent batteries, which has become a global problem. Owing to unfavorable effects of spent LIBs on the economic and environmental aspects, much effort has been made in many countries to manage and recycle the waste batteries. Owing to several restrictions in conventional recycling methods, the use of microorganisms has attracted increasing attention. The bio-hydrometallurgical approaches realize the win-win situation of environmental and economic benefits. In this chapter, the information available on the basic principles and recent developments of the bioleaching of metals from LIBs are reviewed in detail. Additionally, this chapter gives an overview of the previous studies performed in this field. Furthermore, the challenges, limitations, and potential solutions for applying more efficient bioleaching approach for recovery of metals from LIBs are highlighted.
The study of the microbial ecology in extreme acidic environments has provided an important foundation for the development of mineral biotechnology. The present investigation reports the isolation, identification and molecular characterization of indigenous Manganese (Mn) solubilizing acidophilic bacterial strains from mine water samples from Odisha, India. Four morphologically distinct bacterial strains showing visible growth on Mn-supplemented plates of varying pH were isolated and identified. Mn solubilizing ability of the isolates was tested by growing them on Mn-supplemented agar plates. The appearance of lightening around the growing colonies of all the isolates demonstrated their Mn solubilizing ability in the medium. 16 S rRNA sequencing was carried out and the bacterial isolates were taxonomically classified as Enterobacter sp. AMSB1, Bacillus cereus AMSB3, Bacillus nealsonii AMSB4 and Staphylococcus hominis AMSB5. The evolutionary timeline was studied by constructing Neighbor-Joining phylogenetic trees. The ability of acidophilic microorganisms to solubilize heavy metals is supported by five basic mechanisms which include: enzymatic conversion, metal effluxing, reduction in sensitivity of cellular targets, intra- or extracellular sequestration, and permeability barrier exclusion. Such ecological studies undoubtedly will provide insights into Mn biogeochemical processes occurring in leaching environments. The application of acidophilic microbiology in mineral bio recovery and benefication has a large future potential.
The current work was off-shoot of an attempt to isolate a thermophilic pyritic sulfur degrading bacteria in selective medium from a coal mine dump. This thermophilic bacteria (archaea) classified as Sulfolobus was tested for its feasibility to bioleach copper from a low grade Indian chalcopyrite ore (0.3% copper). With its prevalent ability to preferentially attack pyrite (a major phase in the ore), bioleaching was investigated at various parameters of pH, pulp density (PD), particle size, and temperature. A reflective high 85% copper recovery was obtained using <50 μm particles at 20% (w/w) pulp density, pH 2.0, 75 °C in 30 days. The copper dissolution was facilitated by iron (III) available in the leach liquor because of bacterial oxidation of pyrite present in the ore under acidic conditions. The biogenically generated Fe (III) ions enhanced copper dissolution from the chalcopyrite ore. The bioleaching of copper appeared to follow chemical control kinetic model with the reaction of lixiviant-Fe (III) and acid on the surface of the solid. Phase identification by XRD and SEM study corroborated the above mechanism of copper leaching.
The requirement for manganese (Mn) has augmented extensively owing to the intense production of steel and the mounting paucity of natural deposits. The widespread mining, mineral processing, and further human activities have faced a severe consequence in the generation of massive quantity of manganese mining waste residues. The inappropriate supervision and unprocessed liberation of these wastes have resulted in the spread of Mn to the contiguous atmosphere, soil and groundwater pollution, and loads of severe ecological tribulations. Chronic and acute exposure of this metal pollutant leads to lethal consequences and is clinically categorized by the multiple symptoms of neurotoxicity including cognitive and psychiatric symptoms, Parkinson’s disease, manganism, motor system dysfunction, and other neurodegenerative diseases. The advancement of bioremediation technology focuses on accomplishing successful removal of these metal pollutants by increasing the effectiveness of microbes related to metal-solubilizing activities. This chapter describes a complete advance in the research on manganese environmental pollution, manganese compound-induced toxicity, and recent approaches for the microbial remediation of manganese pollutants.
Manufacturing of manganese (Mn) compounds, their industrial applications as well as mining overburden, has generated a potential environmental pollutant. Occupational exposure to elevated levels of Mn occurs during mining, welding, smelting and other industrial anthropogenic sources. Chronic and acute exposure of this metal pollutant leads to adverse consequences and is clinically categorized by various symptoms of neurotoxicity including cognitive, psychiatric symptoms, Parkinson's disease, extra pyramidal signs, manganism, dystonia, and motor system dysfunction. The aim of this review is to summarize the possible mechanism underlying Mn compounds-mediated neurotoxicity leading to neurodegenerative diseases. Our review endeavours to examine recent advances in research on Mn-related environmental pollution, Mn-induced poisoning, molecular mechanisms underlying Mn-induced neurotoxicity with case studies as well as current approaches employed for treatment and prevention of Mn exposure.
Structural models determined by X-ray crystallography play a central role in understanding the catalytic mechanism of enzymes. However, X-ray radiation generates hydrated electrons that can cause significant damage to the active sites of metalloenzymes. In the present study, crystal structures of the multicopper oxidases (MCOs) CueO from
Escherichia coli
and laccase from a metagenome were determined. Diffraction data were obtained from a single crystal under low to high X-ray dose conditions. At low levels of X-ray exposure, unambiguous electron density for an O atom was observed inside the trinuclear copper centre (TNC) in both MCOs. The gradual reduction of copper by hydrated electrons monitored by measurement of the Cu
K
-edge X-ray absorption spectra led to the disappearance of the electron density for the O atom. In addition, the size of the copper triangle was enlarged by a two-step shift in the location of the type III coppers owing to reduction. Further, binding of O
2
to the TNC after its full reduction was observed in the case of the laccase. Based on these novel structural findings, the diverse resting structures of the MCOs and their four-electron O
2
-reduction process are discussed.
Biotechnological applications for metal recovery have played a greater role in recovery of valuable metals from low grade sulfide minerals from the beginning of the middle era till the end of the twentieth century. With depletion of ore/minerals and implementation of stricter environmental rules, microbiological applications for metal recovery have been shifted towards solid industrial wastes. Due to certain restrictions in conventional processes, use of microbes has garnered increased attention. The process is environmentally-friendly, economical and cost-effective. The major microorganisms in recovery of heavy metals are acidophiles that thrive at acidic pH ranging from 2.0-4.0. These microbes aid in dissolving metals by secreting inorganic and organic acids into aqueous media. Some of the well-known acidophilic bacteria such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Sulfolobus spp. are well-studied for bioleaching activity, whereas, fungal species like Penicillium spp. and Aspergillus niger have been thoroughly studied for the same process. This mini-review focuses on the acidophilic microbial diversity and application of those microorganisms toward solid industrial wastes.
The application of leaching process to extracting Mn from a low-grade manganese ore was investigated using a software based design of experiments. Four main parameters, i.e. sulfuric acid concentration, oxalic acid concentration, time and temperature were considered in a central composite response surface design. The recoveries of Mn and Fe were selected as response of design. The optimum conditions under which the Mn and Fe recoveries were the highest and the time and temperature were the lowest were determined using statistical analysis and analysis of variance (ANOVA). The results showed that Mn and Fe recoveries were 93.44% and 15.72% under the optimum condition, respectively. Also, sulfuric acid concentration was the most effective parameter affecting the process. The amounts of sulfuric and oxalic acid were obtained to be 7% and 42.50 g/L in optimum condition and the best time and temperature were 60 min and 65°C.
In recent years, the comprehensive utilization of low-grade manganese oxide ores has received much attention due to the shortage of high-grade manganese ore resources. In this study, low-grade manganese oxide ores were treated by reduction roasting using chemically pure sulfur as a reductant. Then, the roasted samples were subjected to sulfuric acid leaching to extract manganese (Mn). The effects of roasting temperature, roasting time, S/Mn mole ratio, sulfuric acid concentration, leaching temperature, stirring rate, leaching time and liquid-to-solid ratio on the Mn and Fe leaching were discussed. The leaching efficiencies of 95.6% for Mn and 14.5% for Fe were obtained under the following optimized conditions: 550 °C of roasting temperature, 10 min of roasting time, 0.50 of S/Mn, 1.0 mol/L of sulfuric acid concentration, 25 °C of leaching temperature, 200 r/min of stirring rate, 5 min of leaching time and 5:1 of liquid-to-solid ratio.
Manganese leaching and recovery from pyrolusite ore, was investigated by using H2SO4 as a leachant and H2O2 as a reducing agent. The effects of agitation, H2O2 concentration, H2SO4 concentration, liquid/solid mass ratio, leaching time and reaction temperature on manganese recovery were studied. The optimal leaching conditions were determined as 4.0M H2SO4 and 0.8M H2O2 using liquid–solid mass ratio of 5.0 for 90min at 40°C and ore particle size of 44–37μm. Under these conditions, the leaching efficiency was 92.0% for Mn. It was found that the use of H2O2 as a reducing agent for the reductive leaching of manganese increased the leaching rate. Analysis of the experimental results indicted that the leaching process is fitted by a chemical reaction model in temperature range 20–40°C, and at higher temperature, 45–70°C, the diffusion reaction model prevails. Activation energies for these models were calculated to be 49.5kJ∙mol−1 and 10.6kJ∙mol−1, respectively. Based on the experimental results, a separation method and flow sheet were developed and tested to separate high purity MnSO4.H2O (>99.4%). Comparison between the present results and that reported in the literature are given.
Bacterial biomass, potential bacterial production and ectoenzymatic activity were measured at 4 stations along a trophic gradient at the Atlantic Barrier Reef off Belize (Central America). We investigated the changes in the trophic status of this system, which we hypothesized would also lead to changes in the bacterial community. The bacterial community of the oligotrophic station was characterized by low biomass (mean 7.2 mug C l-1) and low potential production rates (mean 9.2 mug C l-1 d-1) as determined by seawater cultures whereas at the most eutrophic station bacterial biomass (mean 18.6 mug C l-1) as well as potential bacterial production (mean 15.5 mug C l-1 d-1) was significantly higher. Oligotrophic bacteria exhibit high potential turnover rates (1.5 d-1). Ectoenzymatic activity measurements with fluorogenic-substrate analogs showed distinct differences in the expression of certain enzymes at different trophic conditions. Alpha- and beta-D-glucosidase activity declined from eutrophic to oligotrophic in both per volume and per cell while leucine-aminopeptidase activity per cell was inversely correlated with the trophic status of the environment. Differences in ectoenzymatic activity are indicated by differences in both v(max) and K(m). K(m) values of leucine-aminopeptidase clearly reflect the trophic situation. Substrate affinity was found to be higher in oligotrophic waters by 2 orders of magnitude as compared to eutrophic environments. Potential activity (v(max)) of the extracellular enzymes tested was found to be correlated to potential bacterial production and bacterial biomass.
Pure manganese dioxide was successfully produced from low grade pyrolusite ore (β-MnO2) and sulphur slag. First, the reduction of β-MnO2, introduced as pure pyrolusite was studied using different ratios of elemental sulphur at different temperature (300–400°C), in air or in closed stainless tube. The reduction process was followed by leaching of Mn with H2O, 0.1, 0.5 or 1 M H2SO4. β-MnO2 was found to undergo a reduction process at obviously low temperature giving Mn3O4, MnS and MnSO4 depending on the applied conditions. The efficiency of Mn leaching ranged from 40 to 99%. The optimum conditions of reduction and leaching were applied to low grade pyrolusite from Um Bogma, Sinai and sulphur slag remained from the sulphuric acid industry. MnSO4 was prepared by concentrating the liquor extract. γ-MnO2 was produced either by precipitation from the liquor extract using ammonium peroxodisulphate or by electrodeposition on platinum anode. The products were characterised by X-ray diffraction, thermal and chemical analysis.
This paper presents results of a feasibility study of recycling manganese furnace dust generated in production of ferromanganese and silicomanganese at Tasmanian Electrometallurgical Company, Australia. Dried man- ganese furnace dust contains about 20 wt% of carbon, in average 33.4 wt% of manganese and 1.3 wt% of zinc. Manganese in the dust is in the form of MnO, Mn 3 O 4 and MnCO 3 ; zinc is mainly in the form of ZnO and ZnSO 4 . Analysis of the zinc balance with dust recycling showed that to keep zinc intake at the acceptable level, it should be partly removed from the dust. In the reduction laboratory experiments, zinc oxide was reduced to zinc vapour by tar of the dust. Reduction of zinc oxide started at 800 o C and zinc removal rate increased with increasing temperature; removal of zinc was close to completion at 1100 o C. Optimal conditions for removing zinc from the dust include temperature in the range 1000-1150 o C, inert gas atmosphere and furnace dust frac- tion in the furnace dust-manganese ore mixture above 60%. In the sintering of manganese ore with addition of manganese dust in the sintering pot, zinc was reoxidised and deposited in the sinter bed. Removal of zinc in the sintering pot tests was in the range 4-17%. Up to 30% zinc removal was achieved from the bottom layer of the sinter bed. It can be concluded that zinc removal will be low during the processing of manganese fur- nace dust in the sinter plant. The zinc removal rate will be the highest when pelletised manganese furnace dust is added to the bottom layer of the sintering bed.
Manganese extraction from a low-grade ore was investigated using cane molasses as a reducing agent in dilute sulfuric acid medium. The effects of concentrations of cane molasses and sulfuric acid, leaching temperature as well as reaction time were discussed. The results showed that high manganese recovery with low Fe and Al extraction yield could be obtained by analyzing the leaching efficiencies of Mn, Fe and Al during the leaching process. The optimal leaching condition was determined as 1.9 mol/L H2SO4 and 60.0 g/L cane molasses for 120 min at 90 °C while using particles smaller than 0.147 mm. The leaching efficiencies were 97.0% for Mn, whereas 21.5% for Al and 32.4% for Fe, respectively.
This research explores the recovery of metals from spent Zn-Mn or Ni-Cd batteries by a bioleaching using six Aspergillus species. Two different nutrients, malt extract and sucrose, were used to produce different types of organic acids. Oxalic acid and citric acid were shown to be the dominant organic acid in malt extract and sucrose media, respectively. In the bioleaching, the metal removal was higher in sucrose media than malt extract. All species, except A. niger KUC5254, showed more than 90% removal of metals from Zn-Mn battery. For Ni-Cd battery, more than 95% of metals was extracted by A. niger KUC5254 and A. tubingensis KUC5037. As a result, A. tubingensis KUC5037 which is a non-ochratoxigenic fungus was considered to have the greatest potential for improving the safety and efficiency of the bioleaching.
Manganese (Mn) ranks twelfth among the most exuberant metal present in the earth's crust and finds its imperative application in the manufacturing steel, chemical, tannery, glass, and battery industries. Solubilisation of Mn can be performed by several bacterial strains which are useful in developing environmental friendly solutions for mining activities. The present investigation aims to isolate and characterize Mn solubilising bacteria from low grade ores from Sanindipur Manganese mine of Sundargh district in Odisha state of India. Four morphologically distinct bacterial strains showing visible growth on Mn supplemented plates were isolated. Mn solubilising ability of the bacterial strains was assessed by visualizing the lightening of the medium appearing around the growing colonies. Three isolates were gram negative and rod shaped while the remaining one was gram positive, coccobacilli. Molecular identification of the isolates was carried out by 16S rRNA sequencing and the bacterial isolates were taxonomically classified as Bacillus anthrasis MSB 2, Acinetobacter sp. MSB 5, Lysinibacillus sp. MSB 11, and Bacillus sp. MMR-1 using BLAST algorithm. The sequences were deposited in NCBI GenBank with the accession number KP635223, KP635224, KP635225 and JQ936966, respectively. Manganese solubilisation efficiency of 40, 96, 97.5 and 48.5% were achieved by MMR-1, MSB 2, MSB 5 and MSB 11 respectively. The efficiency of Mn solubilisation is suggested with the help of a pH variation study. The results are discussed in relation to the possible mechanisms involved in Manganese solubilisation efficiency of bacterial isolates.
Bioleaching of valuable metals (Ga, Ge, V, Sc, La, Eu, Yb) from red mud was examined. Batch and continuous leaching experiments were deployed by using the filamentous fungi, Aspergillus Niger. The leaching results showed that there was a strong negative relation between biomass and pH value. In batch leaching test, the best leaching performance was achieved under spent medium process at 2% pulp density. And in continuous leaching test, the system can reach a steady state at high red mud pulp densities (10%) with a pH value below 3.0. Comparing to organic and inorganic acids leaching, the continuous leaching mode which produces organic acids through glycometabolism by using A. Niger is cost effective in a laboratory scale.
This chapter discusses occurrence and mechanisms of microbial oxidation of Manganese. It examines the biogeochemistry and microbiology of manganese. The chapter focuses on two aspects of the field in which recent progress has been made: field studies of Mn(II) oxidation, including newly developed methods for measuring rates of Mn(II) oxidation and a (2) synopsis of some of the field data that unequivocally establishes the importance of microbes in Mn(II) oxidation in natural systems. The chapter also presents a brief synopsis of some of the field data that unequivocally establishes the importance of microbes in Mn(II) oxidation in natural systems. Finally, the chapter discusses the recent physiological, structural, and biochemical studies of microbial manganese oxidation. In this context, it presents an overview of the chemistry and biology of manganese, which must be understood in order to properly appreciates the field and laboratory studies.
Dumping of low-grade chalcopyrite encompasses several environmental problems. Despite slow dissolution rate, meso-acidophilic bioleaching is preferred for the extraction of copper from such ores. In the present study, meso-acidophilic bioleaching of a low-grade chalcopyrite in presence of an acid-processed waste newspaper (PWp) is discussed for the first time. The study illustrated a strong catalytic response of PWp with enhanced bio-recovery of copper from acid-conditioned chalcopyrite. A maximum of 99.13% copper recovery (0.36% Cu dissolution/day) was obtained in 6 days of bioleaching in presence of 2 gL- 1 PWp in contrast to only 5.7% copper in its absence. FTIR analysis of bioleached residues revealed similar spectral patterns to the original acid-conditioned ore in presence of PWp, thus indicating less development of passivation layer which was also confirmed through a complementary raman characterization of the bioleached residues. Further, a reaction mechanism (chemistry) was proposed suggesting the possible role of PWp as the electron donor under oxygen limiting conditions which facilitated microbial reduction of Fe (III). The resulting biochemical changes provided an energy source for the bacteria, thus allowing free flow of electrons through the ore surface, thus contributing towards enhanced bioleaching of copper.
Fifty percent of sludges produced by wastewater treatment plants in the Province of Québec (Canada) cannot be spread on agricultural land because of their heavy metal content. In this study, leaching of heavy metals by bacteria (Thiobacillus) was achieved for the first time using an aerobic digested sludge. This was done in batch experiments with the addition of a substrate. Different options were tested with reference to time periods required for metal solubilization and sludge digestion. Metal solubilization simultaneous with sludge digestion proved to be a process both slow and difficult to apply. In aerobic digested sludges, metal solubilization took place within one day at a rate of 7·7 mg Cu per liter per day and at initial concentration of 1022 mg/kg dry sludge. Oxidation-reduction potential and pH affect copper solubilization. The importance of the ORP in copper solubilization explains the great rapidity with which this element is made soluble in aerobic sludges. Metal solubilization in aerobic sludges is thus possible and the high rates obtained in this study suggest that 1 day in a continuously-stirred tank reactor (CSTR) or 1 to 2 days in a batch reactor would suffice to to achieve high solubilization efficiencies.
A combined novel process was developed to extract valuable metals from manganese–silver ore. The preferential dissolution of manganese from the primary materials was achieved through reductive leaching in dilute sulfuric acid medium with sodium sulfite as the reductant. Silver, which was enriched in the reductive leaching residue, was leached by complexation dissolution with hydrochloric acid and calcium chloride solution. Effects of process parameters on manganese extraction in the reductive leaching process were investigated, including the average particle size, the amount of sodium sulfite addition, sulfuric acid addition, liquid/solid ratio, leaching temperature and time. As for the silver extraction, the effects of Cl− concentration, hydrochloric acid addition, leaching temperature and time were also addressed. The results suggested that the extraction of manganese and silver could reach 99% and 92% respectively at the optimum conditions, while the high silica-containing product was obtained as the final residue.
The contamination of aquatic sediments with metals is a widespread environmental problem. Coastal aquatic ecosystems with low hydrodynamics need to be periodically dredged in order to maintain the navigation depth and facilitate sailing; consequently large volumes of contaminated sediments need to be managed. Conventional remediation strategies include in-place sediment remediation strategies (e.g. in situ-capping) and relocation actions; in particular, landfill disposal and dumping at sea are still widely applied. Both this options are becoming unsustainable, due to problems associated with contaminant transport pathways, the uncertainties about long-term stability under various environmental conditions, the limited space capacity, costs and environmental compatibility. Alternative approaches have received increased attention; treatment and reuse of contaminated sediments is politically encouraged, but its application is still very limited. Because of the potential human health and environmental impacts of contaminated sediment, different chemical treatments are conventionally applied for contaminated sediments before reuse in other environmental settings. Environmentally friendly techniques developed for soils and other environmental matrices have been investigated for applications with sediments. Biotechnological approaches are gaining increasing prominence in this field and they are often considered as a promising strategy for the eventual treatment of contaminated sediments. In this paper an overview of the main treatment strategies potentially available for sediment contaminated with metals is given, together with a brief overview of the issue associated with the problem of the sediment management.
Lateritic nickel ore from the Sukinda Mines, Orissa, India, was leached using Thiobacillus ferrooxidans, Bacillus circulans, Bacillus licheniformis and Aspergillus niger at 5% (w/v) solid: liquid ratio for 5-20 days. Maximum leaching of Ni was achieved with B. circulans (85%) and Aspergillus niger (92%) after 20 days. Bacillus circulans showed significantly higher rate of leaching than the other organisms giving 80% Ni extraction after 15 days. The importance and usefulness of heterotrophic organisms in metal extraction are discussed.
In this research, the bioleaching mechanism of zinc and lead from high-grade Zn–Pb ore has been investigated. It is done by using mixed culture of iron and sulfur oxidizing moderate thermophilic bacteria at 45 C. Pulp density, initial pH and ferrous concentration were studied as influential parameters in bioleaching experiments. The optimum conditions were achieved at pulp density = 50 (g/L), initial pH = 1 and FeSO4.7H2O concentration = 75 (g/L) with 98.5% zinc recovery after 25 days treatment. Generally, an
increase in ferrous concentration caused an improve zinc recovery, and an increase in initial pH and pulp density caused reduction in zinc recovery. However, in the test with optimum condition the lead dissolution was just 0.027% due to the lower Pb solubility. Furthermore, cadmium dissolution was 98% under optimum condition and results showed the cadmium dissolution was in direct proportion with zinc dissolution.
Finally, 7.82% of arsenic and 8.52% of antimony dissolved during zinc bioleaching after 25 days treatment, both under above mentioned optimum condition.
One hundred and five strains isolated from aquifer sediments andEscherichia coli ML30S were tested for their ability to reduce manganese oxides. Eighty-two strains, includingE. coli, reduced manganese. In most cases the bacterial activity decreased the pH and Eh below 6.75 and 350 mV, respectively, enhancing a spontaneous and nonspecific reduction of manganese. However, for 12 strains the reduction was specifically catalyzed by bacteria; the high pH and Eh values would not permit a spontaneous reduction of manganese. Some of the most active strains were identified as genera common in soils and waters, i.e.,Pseudomonas, Bacillus, Corynebacterium, andAcinetobacter. Two strains were studied in detail. One of the strains, identified asPseudomonas fluorescens, required contact between the cells and the manganese oxides for reduction to occur. The reduction was inhibited by 15 mM of sodium azide. The other strain, identified asAcinetobacter johnsonii, catalyzed manganese reduction by an inductive and dialyzable substance which was excreted by the bacteria. The mechanism involved has not been previously demonstrated.
Laccases (benzenediol: oxygen oxidoreductase; EC 1.10.3.2), a multicopper oxidase enzyme, widely distributed in plants, fungi and bacteria have ability to catalyze oxidation of various phenolic and non-phenolic compounds as well as many environmental pollutants. The diversified functions of laccases, including the antagonistic ones such as their involvement in lignin biosynthesis (in plants) as well as lignin degradation (in fungi and bacteria), make them an interesting enzyme for study from the point of view of their structure, function and application. Important applications of laccases include delignification, pulp bleaching and bioremediation. The ability of laccases to polymerize natural phenols helps to develop new cosmetic pigments, hair dyeing materials, deodorants, toothpastes, mouthwashes and other useful products.
A lab-scale circulation process of electrolytic manganese production with low-grade pyrolusite leaching by SO2 was introduced, exploring its feasibility and stability. Material balances of manganese and sulfur in circulation process were investigated. Results showed that the circulation process was entirely feasible. SO2 absorption efficiency of 99.66% and Mn extraction rate of 95.5% were obtained when a two-stage continuous countercurrent leaching process was used. The electrolytic manganese, meeting the needs of national industry grade standards, could be produced using purified leaching solution. 32 days' continuous running test proved good stability of the circulation process with the current efficiency of 78.1%, electricity consumption of 5396 kW h/t and total Mn recovery rate of 81.77%. The circulation process realized that the electrolytic manganese production with low-grade pyrolusite, has a wide prospect in industrial applications due to the advantages of stable performance, high efficiency and low consumption.
Pressure leaching of manganese smelter dust with air as pressurized gas in a sulfuric acid medium was investigated. Optimum operating parameters were established as follows: liquid-to-solid ratio (mL/g), 5:1; initial sulfuric acid concentration, 120 g/L; leaching temperature, 120 °C; air pressure, 0.8 MPa; ore ratio (manganese smelter dust amount/pyrite amount), 1:0.5; leaching time, 2 h; and agitation speed, 500 r/min. Extraction rates of manganese and iron were obtained at 96.1% and 7%, respectively, under these conditions; and residual percentage of final acid was about 34.9%. Manganese can be effectively separated from impurities, such as iron, through leaching process. Leaching efficiency of manganese increased from 72.9% to 96.1%, whereas that of iron and the residual percentage of final acid both decreased with increase in leaching time from 40 min to 120 min. Pyrite was coated by elemental sulfur when temperature was higher than 119 °C, resulting in its inability to act as a reductant and to react with manganese dioxide. Therefore, leaching temperature must be lower than 120 °C. Pressure leaching technique for manganese smelter dust was proven to be effective and reliable.
Based on the novel technology of Co-recovery of manganese from low-grade pyrolusite and vanadium from stone coal using fluidized roasting coupling technology, the leaching effect of manganese and vanadium has been investigated and many technical conditions have also been optimized. The results indicated that the optimum leaching efficiency of 99.25% for manganese and 91.84% for vanadium could be attained under the conditions that the mass ratio of stone coal to pyrolusite was 3:1, the roasting temperature of stone coal was 1000 °C, the roasting temperature of pyrolusite was 800 °C, the roasting time was 2 h, the sulphuric acid concentration was 2 mol/L, the leaching temperature was 75 °C, and the leaching time was 2 h.
The active seafloor hydrothermal system at Guaymas Basin in the Gulf of California is unique in that spreading centers are covered with thick sediments, and hydrothermal fluids are injected into a semi-enclosed basin. This hydrothermal activity is the source of a large input of dissolved manganese [Mn(II)] into Guaymas Basin, and the presence of a large standing stock of particulate manganese in this basin has been taken as evidence for a short residence time of dissolved Mn(II) with respect to oxidation, suggestive of bacterial catalysis. During a recent Atlantis/Alvin expedition (R/V Atlantis Cruise #7, Leg 11, Jim Cowen Chief Scientist), large amounts of particulate manganese oxides were again observed in Guaymas Basin hydrothermal plumes. The goal of the work presented here was to identify bacteria involved in the oxidation of Mn(II) in Guaymas Basin, and to determine what molecular mechanisms drive this process. Culture-based methods were employed to isolate Mn(II)-oxidizing bacteria from Guaymas Basin hydrothermal fluids, sediments, and plumes, and numerous Mn(II)-oxidizing bacteria were identified based on the formation of orange, brown, or black manganese oxides on bacterial colonies on agar plates. The Mn(II)-oxidizing bacteria were able to grow at temperatures from 12 to 50°C, and a selection of the isolates were chosen for phylogenetic (16S rRNA genes) and microscopic characterization. Endospore-forming Bacillus species accounted for many of the Mn(II)-oxidizing isolates obtained from both hydrothermal sediments and plumes, while members of the alpha- and gamma-proteobacteria were also found. Mn(II)-oxidizing enzymes from previously characterized Bacillus spores are known to be active at temperatures greater than 50°C. The presence of Mn(II)-oxidizing spores - some of which are capable of growing at elevated temperatures - in hydrothermal fluids and sediments at Guaymas Basin suggests that Mn(II) oxidation may be occurring immediately or very soon after hydrothermal fluids emerge from the seafloor.
Metal-oxidizing bacteria may play a key role in the submarine weathering of volcanic rocks and the formation of ferromanganese crusts. Putative fossil microbes encrusted in Mn oxide phases are commonly observed on volcanic glasses recovered from the deep ocean; however, no known Mn(II)-oxidizing bacteria have been directly identified or cultured from natural weathered basalts. To isolate epilithic Mn(II) oxidizing bacteria, we collected young, oxidized pillow basalts from the cold, outer portions of Loihi Seamount, and from nearby exposures of pillow basalts at South Point and Kealakekua Bay, HI. SEM imaging, EDS spectra and X-ray absorption spectroscopy data show that microbial biofilms and associated Mn oxides were abundant on the basalt surfaces. Using a series of seawater-based media that range from highly oligotrophic to organic-rich, we have obtained 26 mesophilic, heterotrophic Mn(II)-oxidizing isolates dominated by α- and γ-Proteobacteria, such as Sulfitobacter, Methylarcula and Pseudoalteromonas spp. Additional isolates include Microbulbifer, Alteromonas, Marinobacter, and Halomonas spp. None of the isolates, nor their closest relatives, were previously recognized as Mn(II) oxidizing bacteria. The physiological function of Mn(II) oxidation is clearly spread amongst many phylogenetically diverse organisms colonizing basalt surfaces. Our findings support a biological catalysis of Mn(II) oxidation during basalt-weathering, and suggest heterotrophic Mn(II) oxidizing bacteria may be ubiquitously associated with submarine glasses within epilithic and endolithic biofilms.
Manganese‐oxidizing microorganisms have been implicated in the deposition of manganese in dark manganiferric rock varnish coatings on desert rocks. For this study, a collection of bacteria able to oxidize manganese has been obtained from rock varnish samples from the Sonoran and Mojave Deserts. Two groups of organisms predominated among the isolates. One group was identified as Arthrobacter spp. based on their rod‐coccus transformations, cell shapes, postfission division stages, and physiological characteristics. Another major group consisted of gram‐positive cocci tentatively ascribed to the genus Micrococcus. In addition, single isolates of Bacillus sp., Planococcus sp., Streptococcus sp., and Hyphomonas sp. were identified as manganese‐oxidizing bacteria. Some isolates grew too poorly to be easily characterized and identified.
Previous studies identifying Fe3+ as the main oxidizing agent in CuFeS2 bioleaching suggests that if the precipitation of additional Fe3+ could be prevented, the Cu extraction yields should be enhanced. In this respect, the acid-generating nature of the biologically mediated oxidation of additional S0 to H2SO4 should theoretically serve as a pH regulator as well as biomass generator. This should prevent the precipitation of Fe3+ and attenuate the biomass reduction caused by the inhibitory effect of high Fe3+ concentrations. To prove the former hypothesis, three thermophile strains were employed for bioleaching of chalcopyrite under various additional S0 and Fe3+ concentrations. The hypotheses about additional S0 application were fully confirmed; the addition of S0 alone enhanced the leaching rates with A. brierleyi and M. sedula in media at initial pH 2. Although higher initial leaching rates were obtained with additional Fe3+, its role as the main leaching factor is questioned; leaching with thermophiles appears to depend on the availability of protons and ORP rather than on the prevention of Fe3+ precipitation. Additional S0 in media with high Fe3+ concentrations has shown the best improvements in the case of bioleaching with A. brierleyi, whereas improvements in bioleaching with M. sedula and S. metallicus were less notable.
Cells of a soil Arthrobacter sp., and the manganese oxide they formed rapidly adsorbed manganous ions (Mn2+) from aqueous solutions. These ions could be desorbed by copper ions. There was no evidence that the adsorbed manganous ions were rapidly oxidized by non biological reactions. In gently stirred mixtures of cells and manganous ions the maximum rate of oxidation occurred at pH 6.5. The rate was very sensitive to small changes in pH below about pH 5.7 and above about pH 7.5. No oxidation occurred at pH 5.4 or at pH 7.9. Manganous ion concentrations between 0.5 mM and 6 mM had little effect on the maximum rate of oxidation. Higher concentrations became progressively inhibitory and 40 mM was completely inhibitory. The concentration for half the maximum rate was about 0.1 mM. Within limits the rate of oxidation increased in direct proportion to the numbers of bacteria in suspension. In deep vessels, static suspensions of the bacteria reduced bacterial manganese oxide and the rate of reduction was increased greatly by small additions of methylene blue. Methylene blue also partially inhibited the oxidation of manganese by cell suspensions in shallow vessels. These results are discussed in relation to manganese transformations in soil.
The leaching of copper, nickel and cobalt from polymetallic manganese nodules from the Indian Ocean was investigated using a fungus — Aspergillus niger. Parameters such as initial pH, pulp density, particle size and duration of leaching were optimized for the bio-recovery of metals. At an initial pH of 4.5, 35ºC temperature and 5% (w/v) pulp density, about 97% Cu, 98% Ni, 86% Co, 91% Mn and 36% Fe were dissolved in 30days time using adapted fungus — as against only 4.9% Cu, 8.2% Ni, 27% Co, 6.3% Mn and 7.1% Fe solubilized in control experiment. The results indicate that A. niger released organic acids such as oxalic and citric acids which in turn reduced the host metal oxides/hydroxides to their lower valence states, and thus dissolving the base metals following the indirect mechanism. A comparison of results obtained with chemical leaching of sea nodules using citric and oxalic acids and bio-leaching using A. niger show that the leaching of metals was more effective in presence of the fungus. The appearance of some lower oxide phases of manganese and iron in the leach residue identified by XRD phase analyses may account for unlocking of the host lattice leading to release and dissolution of metals during leaching.
Extraction of manganese from manganese dioxide ores was investigated using corncob as a reducing agent in dilute sulfuric acid medium. The effects of corncob amount, concentration of sulfuric acid, leaching temperature, reaction time and ore particle size were discussed. The leaching efficiency of manganese reached 92.8% while iron dissolved was 24.6% under the optimal condition which was determined for 10g of manganese dioxide ore as corncob amount of 3g, ore size of 75μm, sulfuric acid concentration of 1.9mol/L, leaching temperature of 85°C for 60min. In a word, the method provided a good leaching yield while making a productive use of corncob.
Thin polished sections of copper sulphide ore were placed as an energy source in stationary cultures of wild strains and Thiobacillus neapolitanus at pH 7.5. Scanning electron microscopy revealed characteristic leaching patterns that depended on the type of leaching process and time of bioleaching. In some cases, a biological film on the ore surface was observed. Close contact between bacterial cells and ore seems necessary for leaching in some cases.