bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic Carbon Utilisation by Iron(II)-Oxidising Bacteria Sulfobacillus thermosulfidooxidans and Alicyclobacillus Strain FP1 that Inhabit Copper Sulfide Leaching Heaps
Authors: Shiers Denis W. , Collinson David M. , Watling Helen R.
Published: December 2015

Strains ofSulfobacillus (S.)andAlicyclobacillusspecies have been identified/detected in managed bioleaching heaps and agitated tanks using culture-dependent and culture-independent methods.S thermosulfidooxidansoxidises both iron(II) and reduced inorganic sulfur compounds (RISC). Several strains were isolated from a copper sulfide heap in North Western Australia.Alicyclobacillusstrain FP1 (FP1) was also isolated from the heap and oxidises iron(II) but not RISC. However, the species exhibit differentiating characteristics during growth on D-glucose, which has been explored using a suite of monitoring and measurement techniques. As examples, a growth factor (yeast extract) is essential for FP1 but not forS. thermosulfidooxidans, although yeast extract is beneficial to the latter. FP1 grows well on glucose, compared with the poor-to-no growth ofS. thermosulfidooxidanson the substrate. Solution pH strongly influences the activity of both species when grown on organic substrates, suggesting a pivotal role for solution acidity in the growth and activity of heterotrophs or mixotrophs in heap leach systems. This research forms part of an ongoing development of a data base with which to interpret the impacts of leaching conditions in heaps on microbial activity without having to disrupt metal production by invasive sampling campaigns. The insights gained will assist in understanding the effects that changing conditions in heaps due to acid consumption and/or increased element concentrations in process water may have on microbial activity.
Bioleaching of Complex Refractory Gold Ore Concentrate of China: Comparison of Shake Flask and Continuous Bioreactor
Authors: Song Yan , Yang Hong Ying , Tong Lin Lin
Published: December 2015

The laboratory tests of biooxidation and cyanidation were carried out by using samples of the complex refractory gold ore from China. The elemental composition was 16.8 % iron, 18.6 % sulfur, 4.88 % arsenic，2.30 % carbon and 3.49 % antimony. Gold is assayed at 46 g/t. The arsenic oxidation of 88.11 %，carbon removal rate of 32.34 % and antimony oxidation of 23.92 % over 16d was achieved in shake flasks in the presence of the mixed culture (HQ0211: Thiobacillus ferrooxidans Leptospirillum ferrooxidans and Thiobacillus thiooxidans). The continuous bioreactor tests resulted in greater dissolution rates for arsenic, carbon and antimony, which led to a greater extent of sulphide oxidation within a shorter period of time. The maximum oxidation of arsenic and antimony was 90.72 % and 40.09 % respectively and the removal rate of carbon is 63.48% after 8d in the continuous bioreactor tests. After bioleaching, the gold recovery of the oxidation residue was 98.02 % with the cyanidation method, which was showed the biological pretreatment was applicable to the complex refractory gold ore.
Comparative Experiments on Acid Leaching and Bioleaching to a Sandstone Type Uranium Ore
Authors: Liu Jin Hui , Shi Wei Jun , Liu Ya Jie , Zhou Yi Peng , Sun Zhan Xue
Published: December 2015

512 uranium deposit, located in the northwest of China, is one of the largest in-situ leaching uranium mine in China. In the last 2 decades, The V cyclothem Deposit in 11 mining areas were successively mined by acid in-situ leaching. The uranium recovery rate in the roll body was very high, in contrast it was very low in wing body. To compare the efficiency of uranium recovery in No.11-3 mining area, in which the uranium recovery rate was less than 40% by acid leaching in more than 10 years, acid leaching and bioleaching experiments in lab scale were carried out respectively with a native mix cultures isolated and domesticated with the raffinate from this uranium ore in this paper. The experiments mainly focused on the influences of acidity and ferric ion concentration of the solution to uranium recovery. 12 flask bioleaching tests were set up with acidity of 2g/L, 3.5 g/L and 5 g/L , while ferric ion concentration of 0 g/L, 2g/L, 3.5 g/L, and 5 g/L，respectively. The results showed that the average bioleaching rate was 9.8% higher than that of acid leaching. And when the tailings after acid leaching was leached by bacteria culture, uranium concentration in the solution was 115.74% higher than that when in acid leaching. The average leaching rate of uranium increased 5.7%. It concluded that bioleaching is better than acid leaching to this type of minerals.
Comparative Study of Iron and Sulfur Speciation Transformation of Pyrite and Marcasite by Extreme Thermophilic Archaea Acidianus manzaensis
Authors: Liu Hong Chang , Xia Jin Lan , Nie Zhen Yuan , Zhu Hong Rui , Zhao Yi Dong , Ma Chen Yan , Zheng Lei , Hong Cai Hao
Published: December 2015

Differential utilization of isomers pyrite and marcasite by Acidianus manzaensis were comparatively studied, besides the iron and sulfur speciation transformation of the minerals was also investigated based on synchrotron radiation X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the biooxidation of pyrite was faster than marcasite. The bioleached surface of both pyrite and marcasite are serious corroded, and the Fe (III)-containing species as well as jarosite were gradually produced, and more elemental sulfur species were formed on the marcasite surface than that for pyrite. It demonstrates the mineral structure does affect the biooxidation of pyrite and marcasite, and the more precipitated elemental sulfur might be one of the reasons leading to lower oxidation rate of marcasite by A. manzaensis.
Characteristics of Acidibacillus Spp.: A Novel Genus of Acidophilic Iron-Oxidising Firmicutes
Authors: Holanda Roseanne , Hedrich Sabrina , Falagán Carmen , Ňancucheo Ivan , Dall`Agnol Hivana , Grail Barry M. , Johnson D. Barrie
Published: December 2015

Strains of acidophilic bacteria, isolated from different global locations, were shown to be representatives of a novel genus within theFirmicutesphylum. All isolates oxidised and reduced iron and catalysed the oxidative dissolution of pyrite. Together they formed two distinct phylogenetic clusters, one of which included mesophilic strains that did not oxidise sulfur, and the other thermotolerant/moderately thermophilic strains that could oxidise sulfur. The novel genusAcidibacillusis proposed for these new isolates, to includeA. ferrooxidans(mesophilic iron-oxidising strains) andA.sulfooxidans(moderately thermophilic iron-and sulfur-oxidising strains) as candidate species.
Bioleaching of Orpiment (As2S3) in Absence of Fe3+
Authors: Zhang Guang Ji , Yang Qiao , Yang Chao
Published: December 2015

Abstract Orpiment (As2S3) is one of the major arsenic sulfide minerals, which can be dissolved by ferric ion and proton produced by the bacteria, and the main intermediates were polysulﬁdes and elemental sulfur. In this study, two strains (Acidithiobacillus thiooxidans and Acidthiobacillus caldus) were used to bioleach the orpiment without iron ions addition. The experimental results show that both the two strains can grow in the pulp and dissolve the orpiment. In the bioleaching, it was found that pH decreased, the concentration of arsenic increased significantly and no elemental sulfur is detected on the surface of the residuals. At the same time the density of the planktonic bacteria increased obviously. These results indicate that the orpiment can be dissolved by the bacteria easily in absence of Fe3+. This study suggests that the release of arsenic which is from orpiment in the mining tailings can be faster than expected in open air.
Influence of Biological and Environmental Factors on Leaching Efficiency during Chalcopyrite Bioleaching Process
Authors: Ma Li Yuan , Wang Xing Jie , Feng Xue , Guo Xue , Hu Qi , Xiao Yun Hua , Hao Xiao Dong , Liang Yi Li , Yin Hua Qun , Liu Xue Duan
Published: December 2015

In the bioleaching process, many factors in ore, water and sediments are important contributors as driving forces to improve leaching efficiency. In this study, FeSO4·7H2O and S0as energy substrates were added to an oxide-rich, low-grade copper ore to explore the influence of biological and environmental factors on leaching efficiency. Mantel test results showed that the leaching rate was significantly correlated with biological and environmental factors with r values of 0.78 and 0.63 respectively, indicating that influence of biological factors were more significant. It cannot be ignored that environmental factors were important to construct the microbial community. Real-time quantification polymerase chain reaction (RT-qPCR) showed that the dominant and minor species wereA. caldusandA. ferrooxidans. Canonical correspondence analysis (CCA) made it clear that pH and ferrous concentration were crucial for shaping microbial community. All results are of great significant to gain the optimal leaching condition on Zambia oxide-rich, low-grade copper ore.
Chalcopyrite Bioleaching at High Sulfate Concentrations
Authors: Rea Suzanne M. , Boxall Naomi J. , Li Jian , Morris Christina , Kaksonen Anna H.
Published: December 2015

The efficiency of chalcopyrite bioleaching in a high sulfate background was evaluated using acidophilic microorganisms adapted to sulfate. The concentration of magnesium sulfate added to mesophilic, moderately thermophilic and thermophilic bioleaching tests was equivalent to 100, 40 and 80 g L-1SO42-, respectively. Biological copper extraction was highest at 45 °C (67 %), followed by 60 °C (54 %) and 30 °C (16 %). Quantitative x-ray diffraction (QXRD) analysis of the ROM ore and bioleached residues revealed the complete disappearance of pyrrhotite and a significant reduction of pyrite at all temperatures. Significant chalcopyrite was leached at 45 and 60 °C; however, no chalcopyrite was leached at 30 °C. As the bioleach did not plateau after 31 days, it is possible that higher copper yields may have been achieved with prolonged leaching.
Different Leaching Efficiency and Microbial Community Structure Variation in Chalcopyrite Bioleaching Process Based on Different Initial Microbe Proportions
Authors: Feng Xue , Ma Li Yuan , Deng Yan , Chen Ai Jia , Zou Kai , Liang Yi Li , Qiu Guan Zhou , Liu Xue Duan
Published: December 2015

In order to investigate the effect of initial proportions of microorganisms on chalcopyrite leaching, six typical bioleaching strains were used to rebuild different co-culture systems. According to their different energy use types,Acidithiobacillus ferrooxidansDX2012 (ferrous and sulfur),Sulfobacillus thermosulfidooxidnasDX2012 (ferrous and sulfur),Leptospirillum ferriphilumDX12 (only ferrous),FerroplasmathermophilumL1 (only ferrous),Acidithiobacillus caldusDX2012 (only sulfur),Acidithiobacillus thiooxidansA01 (only sulfur) were classified to construct four groups(cells): a, 1:1:1:1:1:1; b, 10:10:1:1:1:1; c, 1:1:10:10:1:1; d, 1:1:1:1:10:10. The results showed that leachate pH of consortium a, d firstly began to decline until stabilized at 1.4. On day 9th, Eh of consortium d began to sharply rise and finally stabilized at 720 mV. Compared with consortium a, b and c, copper concentration of consortium d increased to the highest level of 6000mg/L. All the evidence suggests consortium d is the best combination which held the highest leaching rate of copper. Real-time quantification polymerase chain reaction (RT-qPCR) was used to analyze the population dynamics during all the bioleaching process. Final microbial community structure of four consortia was trended roughly the same and consortium d was first to reach final community structure on day 27th. It is concluded that bioleaching co-culture system containing a higher proportion of sulfur-oxidizing bacteria works more efficiently.
Enhance Column Bioleaching of Uranium Embedded in Brannerite by a Mesophilic Acidophilic Bacteria
Authors: Wang Xue Gang , Li Jiang , Sun Zhan Xue , Liu Ya Jie
Published: December 2015

The column chemical leaching and bioleaching methods recovery of uranium from one uranium ore containing brannerite under the some conditons were investigated. The brannerite ore sample taken from one uranium mine in southern China, the ore particle size was crushed to -5mm, the uranium content is 0.281%. The leaching duration lasted 120 days, the acid consumption rate were 7.82% and 7.79% by ore weight, the slag uranium leaching rate were 89.32% and 91.46% that calculated by its residue has been recovered. This work has indicated that column bioleaching can enhance 2.14% uranium recovery percentage than chemical oxidation leaching, bioleaching be the promising method for uranium extraction from refractory brannerite ore in the deposit.
Microbial Community Structure Analysis of Blood Pond Hell Hot Spring in Japan and Search for Metal-Reducing Microbes
Authors: Masaki Yusei , Hirano Shin Ichi , Okibe Naoko
Published: December 2015

Blood Pond Hell (Chinoike Jigoku) is located in the hot spring town of Beppu, in Kyushu Island of Japan, and features a unique hot, acidic, red-coloured pond. This study aimed to investigate the microbial diversity in this unique extreme environment and eventually to isolate useful acidophilic microbes. The initial PCR (using bacteria-or archaea-specific primers) on environmental samples detected the presence of bacteria, but not archaea. The following random sequencing analysis confirmed the presence of a large bacterial diversity at the site (123 clones comprising 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillussp.,Sulfobacillussp.,Alicyclobacillussp.). Nonetheless, successive enrichment cultivation with Fe (III) under oxygen depletion lead to isolation of previously non-detected archaeal (Sulfolobussp.) colonies on solid media. Two isolates showing Fe (III) reduction ability were namedSulfolobussp. GA1 and GA2. The isolates were also found to reduce highly toxic Cr (VI) to less toxic/soluble Cr (III), demonstrating their potential utility in metal bioremediation.
Column Bioleaching of Refractory Gold Ores
Authors: Bulaev Aleksander , Kanayeva Zylikha K. , Muravyov Maxim I. , Kanayev Ashimkhan T. , Kondrat'eva Tamara F.
Published: December 2015

Refractory sulfide ores are ubiquitous resources of gold around the world. It was demonstrated that biooxidation pretreatment of refractory whole ores could be conducted in heaps. The effectiveness of column biooxidation of off-balance gold ores from Bakyrchik and Bolshevik deposits (northeast Kazakhstan) containing pyrite and arsenopyrite was examined in the laboratory. Bakyrchick ore contained 1.5% of pyrite, 3% of arsenopyrite and 4.5 g/t of gold. Bolshevik ore contained 1% of pyrite, 1% of arsenopyrite and 10.7 g/t of gold. The recovery rates of gold from the Bakyrchik and Bolshevik ores by direct cyanidation were 4.5% and 8.2%, respectively. Representative samples of each ore were processed in air-lift percolators. A bioleaching experiment was performed in duplicate. The enrichment culture was obtained from the pyrite flotation wastes and used as an inoculum. Bioleaching was conducted for 60 days at ambient temperature (20-25°C). The recovery rates of gold from the bioleaching residues of Bakyrchik and Bolshevik ores by cyanidation were 21.0% and 48.5%, respectively. The results obtained in the present work may be used to estimate perspectives of heap bio-oxidation for the recovery of gold from these sulfide ores.
Differential Surface Properties and Iron Distribution of Acidianus manzaensis YN25 Grown on Four Different Energy Substrates
Authors: Nie Zhen Yuan , Liu Hong Chang , Xia Jin Lan , Yin Zi Wei , Liu Li Zhu , Song Jian Jun , Zhu Hong Rui , Yang Yun , Zhen Xiang Jun , Qiu Guan Zhou
Published: December 2015

The surface properties and iron distribution of Acidianus manzaensis YN25 grown on four different energy substrates (chalcopyrite, pyrite, S0, and Fe2+) were comparatively studied. The results showed different growth and absorption features of A. manzaensis grown on different energy substrates. Results also showed that Zeta potentials, adsorption forces and cell surface acid-base properties were significantly influenced by the growth condition. Studies based on FT-IR and UV-vis spectroscopy indicated that the differences in cell surface properties may result from the different amounts of proteins and iron distribution on the cell surface of A. manzaensis grown on different growth conditions. The SR-μ-STXM images showed that the cell surface densities of iron spread on the cells grown on chalcopyrite, pyrite, S0 or Fe2+ were 4.31×10-5 - 23.25×10-5 g/cm2, 4.43×10-5 - 20.24×10-5 g/cm2, 0.10×10-5 - 0.29×10-5 g/cm2, and 6.45×10-5 - 24.06×10-5 g/cm2, respectively, further indicating that the surface of A. manzaensis cells grown on chalcopyrite, pyrite and Fe2+ had an iron-contained compounds, which might be the reason why the surface of A. manzaensis cells grown on chalcopyrite, pyrite and Fe2+ carried weak positive charges at pH 2 while negative for the cells grown on S0.
Microbial Leaching of Copper from Tailings of Low Grade Sulphide Ores in Zambia
Authors: Liang Yi Li , Yin Hua Qun , Xiao Yun Hua , Tang Min , Feng Xue , Xie Zhi Yong , Qiu Guan Zhou , Liu Xue Duan
Published: December 2015

Demand for copper is growing in the world,which makes it increasingly necessary to process low-grade ores and tailings that used to be considered as wastes. The development and application of bioleaching by acidophilic chemolithotrophic microorganisms, which obtain energy from the oxidation of sulfide minerals and use carbon dioxide for constructive metabolism, has been a major approach for processing the low-grade copper ores. In this study, mixed culture consisted of six iron and sulfur oxidizing microorganisms were used in leaching of flotation and acid-leaching tailings obtained from Zambia sulfide ores. The result showed that 62.7% and 61.7% copper were dissolved by bioleaching, while 53.8% and 57.4% by acid leaching in flotation and acid leaching tailings, respectively. In addition, mineralogical forms of copper were quite noteworthy since copper sulfide mineral extraction was significantly improved in bioleaching. XRD analysis showed wollastonite and diopside in acid tailing were undetectable after 23 days while others were difficult to be dissolved. No jarosite or sulphur was detected by XRD in residues.
Possible Role of the Biosurfactant-Producing and Fe-S-Oxidizing Bacterium in Silicate and Sulfide Bioflotation Processes
Authors: Sanwani Edy , Zendy Mirahati Riria , Chaerun Siti Khodijah
Published: December 2015

A biosurfactant-producing-and Fe-S-oxidizing bacterium, namely Pseudoclavibacter sp. strain SKC/XLW-1, was studied in an attempt to seek more benign alternatives for the replacement of relatively toxic chemical reagents in the flotation of silicate and sulfide minerals. Our study showed that Pseudoclavibacter sp. SKC/XLW-1 was capable of yielding biosurfactants as evidenced by a decrease in the surface tension of the solutions and an increase of the contact angle of the pyrite or silica surfaces as a function of time. This bacterial strain was also observed to promote the oxidation of pyrite, thus generating Fe-oxides as well as sulfuric acid as indicated by a decline of the solution pH and FTIR analysis. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS) observations of the silica-or pyrite-bacterial cell complexes revealed the presence of bacterial cell aggregation along with silica or pyrite, where silica or pyrite particles become embedded in the biofilm matrix. It is suggested from this study that the bacterium Pseudoclavibacter sp. SKC/XLW-1 could potentially be applicable as the flotation bioreagents (collector, frother or depressant) for both silicate and sulfide flotation processes.
Uranium (VI) Sorption Using Functionalized-Chitosan Magnetic Nanobased Particles
Authors: Galhoum Ahmed A. , Mahfouz Mohammad G. , Gomaa Nabawia M. , Vincent Thierry , Guibal Eric
Published: December 2015

Hybrid materials were synthesized by chemical grafting of different compounds (diethylenetriamine DETA, cysteine, alanine and serine) on chitosan/magnetite nanoparticles. The sorbents were characterized by TEM, XRD and FTIR analysis and vibrating sample magnetometry (VSM) before being tested for uranium sorption. The nanometric size of sorbent particles reduces the impact of diffusion resistance and uptake kinetics are quite fast. Sorption isotherms are modeled by the Langmuir equation. The sorption is spontaneous and exothermic. Uranium is desorbed using acidic thiourea and the sorbent can be recycled for at least 4/5 cycles.
Selective Recovery of Au(III) from Binary Metal Solution Using Aliquat-336-Impregnated Alginate Capsule
Authors: Wei Wei , Song Myung Hee , Kim Sok , Bediako John Kwame , Yun Yeoung Sang
Published: December 2015

Aliquat-336-impregnated alginate capsule (Aliquat-336-AC) was fabricated using a facile method. Ionic liquid Aliquat-336 was used as a model extractant owing to its good extraction performance toward precious metals (PMs). Aliquat-336-AC was prepared by dropping the mixture solution (Aliquat-336 + Tween 80 + CaCl2) into the alginate solution. CaCl2was used to form Ca-alginate shell, leading to Aliquat-336-AC. Two types of binary metal solutions, Au (III)/Pt (IV) and Au (III)/Pd (II) were used to evaluate metal sorption capacity of Aliquat-336-AC. The maximum Au (III) uptake in Au (III)/Pt (IV) and Au (III)/Pd (II) systems were 61.38 and 82.97 mg/g, respectively. Whereas, the uptakes of Pt (IV) and Pd (II) were almost closed to zero, indicating excellent Au (III) selectivity of Aliquat-336-AC. A comparative study was carried out between liquid/liquid extraction (LLE) using Aliquat-336 and solid/liquid adsorption (SLA) using Aliquat-336-AC for Au (III) selective recovery from Au (III)/Pt (IV) and Au (III)/Pd (II) solutions. The data of selectivity coefficients (αsel) showed that the values of αAu/Ptand αAu/Pdwere 10253.34 and 5817.61 in the SLA system, respectively. These values were much higher than 2033.38 of αAu/Ptand 1879.80 of αAu/Pdin the LLE system. Therefore, Aliquat-336-AC can be used as a selective adsorbent for Au (III).
Organic Sulfur Reduction on Lignite Coal Using Multistage Artificial Biotreatment (A-Bmt)
Authors: Paisal Yustin , Handayani Ismi , Chaerun Siti Khodijah , Soepriyanto Syoni
Published: December 2015

This study focuses on the biodesulfurization of lignite specifically the reduction of organic sulfur, namely aliphatic mercaptans/thiolsviabioprocess methods. The process was conducted by using multistage artificial biotreatment (A-Bmt) andPseudoclavibactersp.SKC/XLW-1 strains as biocatalysts. The aims are to improve the recovery of clean coal by reducing the organic sulfur both in nodules and globular forms on the maceral surface during the stage of coal biooxidation prior to column bioflotation stage, in which it is still possible to achieve higher recovery of fine coal grains without sulphide mineral. The results shows that the A-Bmt method carried out through biooxidation stage followed by column bioflotation stage has better performance compared to the method without biooxidation stage. The results of this study show that the content of organic sulfur are lower by 25%.
Passive System for Bio-Recovery of Copper from Acid Mine Drainage
Authors: Schwarz Alex , Chaparro Gustavo , Pérez Norma
Published: December 2015

In Central Chile, acid mine drainages (AMDs) are characterized by high concentrations of copper, which can be recovered. Passive biochemical reactors are eco-friendly technologies for the treatment of AMD. They use organic substrate mixtures to drive microbial sulfate reduction and metal sulfide precipitate formation. The performance of conventional biochemical reactors, however, is limited by metal toxicity, and metal recovery is difficult.
Diffusive exchange systems on the other hand can be tailored to resist metal toxicity. This is achieved by having separate zones for AMD movement and for sulfate reduction, and by allowing the diffusive exchange of solutes between these zones. Also, higher reaction rates are possible, because much finer organic materials can be utilized as substrates. A key innovation of this research is the use of vertical tubular screens to convey the AMD through the reactor while simultaneously allowing transverse diffusive exchange of dissolved species with the substrate. The tubular screens act as reactors for precipitate formation, settling and accumulation, from where precipitates can be periodically recovered. This design promotes higher reaction rates, eliminates clogging and facilitates the recovery of valuable metals.
This work studied the performance of a 2-m long vertical diffusive exchange column. Detailed insight was gained into reactions and transport processes within the tubular screen by the use of several sampling points along the column. During the first two months the reactor was fed with increasing concentrations of sulfate only, to determine its sulfate reduction potential. Then the reactor was fed with AMD for three additional months. During the operation with AMD, significant metal removal occurred, and copper precipitates accumulated, and were recovered.
Biosynthesis of Zinc Sulfide Quantum Dots Using Waste Off-Gas from Metal Bioremediation Process
Authors: Roussel Jimmy , Murray A.J. , Rolley John , Johnson D. Barrie , Macaskie L.E.
Published: December 2015

Dissimilatory reduction of sulfate, mediated by various species of sulfate-reducing bacteria (SRB), can be used to remediate acid mine drainage (AMD). Hydrogen sulfide (H2S/HS-) generated by SRB can be used to remove toxic metals from AMD as sulfide biominerals. For this, SRB are usually housed in separate reactor vessels to those where metal sulfides are generated; H2S is delivered to AMD-containing vessels in solution or as a gas. This allows more controlled separation of metal precipitation and facilitates enhanced process control. Industries such as optoelectronics use quantum dots (QDs) in, for example, light emitting diodes and solar photovoltaics. QDs are nanocrystals with semiconductor bands that allow them to absorb light and re-emit it intensely at specific wavelength couples. Small nanoparticles have the possibility to get electrons shifted to a higher energy and then emit light during the relaxation phase. The QD elemental composition and the presence of doping agent determines its electronic band gaps and can be used to tune the QD to desired emission wavelengths. Traditional QD production at scale is costly and/or complex. Waste H2S gas from growth of SRB has been used to make zinc sulfide QDs which are indistinguishable from ’classically’ prepared counterparts with respect to their physical and optical properties. Clean recycling of minewater bioremediation process waste gas into high value QD product is described.
Enhancing ARD Mitigation by Application of Benign Tailings to Reduce the Permeability of Waste Rock Dumps
Authors: Kotsiopoulos Athanasios , Harrison Susan T.L.
Published: December 2015

ARD mitigation is considered by reducing the permeability of acid-generating coal interburden waste rock dumps. Fine desulfurised benign tailings were used to conceal exposed surface active sites from air, water and more aggressive sulfur-and iron-oxidizing microorganisms in acidic environments. Test columns containing interburden waste rock co-disposed with benign tailings were configured as either alternating layered covers or as a blended mixture of tailings and discards. Demonstration of the efficacy of the procedure was assessed by analyzing effluent solution concentrations of the concurrently operated simulated ore beds following inoculation with micro-organisms implicated in bioleaching (biotic mode) or in the absence of inoculation (abiotic mode). The presence of fine tailings both minimized the infiltration of oxidants to the porous ore and void space within the packed bed and provided neutralisation. In biotic mode, tests with layered covers of desulfurised tailings were less successful at limiting microbial activity and associated accelerated oxidation reactions. Blended columns resulted in reduced leaching reactions and an increase in the mean residence time of the solution phase. By increasing the solution residence time, an aqueous cover was concurrently formed, evolving into a bifunctional mitigating measure
Enrichment and Isolation of Acidophilic Microorganisms from Sediments of Gold Mine Waste Leachate
Authors: Bulaev Aleksander , Pimenov Nikolay V. , Ivasenko Denis A. , Karnachuk Olga V.
Published: December 2015

Microorganisms living in acidic environments associated with various types of mining wastes can be used for bioremediation of acid mine drainage (AMD) and related waste streams. We studied microbial diversity of the acidic sediments of a leachate puddle at the basement of a waste rock pile from gold mining in abandoned gold deposit in Martiga (Kemerovo region, West Siberia, Russia). The enrichments were established from four sediment samples with a pH ranging from 2.29 to 6.16. The enrichments cultures were set up at aerobic and anaerobic conditions. Pure cultures of bacteria involved in iron and sulfur oxidation were isolated. The isolated iron- and sulfur-oxidizing cultures were affiliated withAcidithiobacillusandAcidocellagenera as was revealed by 16S rRNA gene sequencing. Strains ofDesulfosporosinus-like spore-forming bacteria were isolated under anaerobic conditions. The pure culture isolates physiological and biochemical characterization is underway, which will provide new knowledge of AMD formation and natural processes of metal attenuation. The strains can also be prospective agents for use in bioleaching and bioremediation processes.
Neutrophilic Microbial Community with High Rate of Elemental Sulfur Oxidation
Authors: Belyi A.V. , Kondrat'eva Tamara F. , Bulaev Aleksander , Solopova N.V. , Grigor’eva N.V. , Murav’yov M.I. , Panyushkina A.E. , Tsaplina I.A.
Published: December 2015

Using molecular genetic methods, 10 species wereidentified in the community of neutrophilic microorganisms isolated from thebioreactor during the process of biooxidation of gold-arsenicpyrrhotite-bearing sulfide ore flotation concentrate. The microbial communitywas composed of chemolithotrophs oxidizing elemental sulfur and its reducedcompounds and chemoorganotrophs. The predominant S0-oxidizingchemolithotrophic strain and 3 strains of chemoorganotrophs were isolated inpure cultures. Phylogenetic identification of the pure cultures revealed thechemolithotrophic microorganism to belong to Thermithiobacillus tepidarius,while organotrophic microorganisms were identified as Parapedobacter sp.,Nocardioides nitrophenolicus, and Nocardioides sp. Themorphological and physiological characteristics of Thermithiobacillustepidarius and Nocardioides nitrophenolicus, the culturespredominant in the community of neutrophilic microorganisms, were studied.Active growth of T. tepidarius occurs within a temperature range of38–48°C at the optimal pH value of 7.0–7.5. The maximal specific growth rate ofT. tepidarius on sulfur and on solid residue which remains after theprocess of bioleaching/biooxidation of sulfide ore flotation concentrate (biooxidationresidue) was 0.13 and 0.135 h-1, respectively. The average maximalrate of S0 oxidation in the biooxidation residue was 0.107 g S0oxidizedper g S0initial h-1. The ability of Nocardioidesnitrophenolicus to destruct thiocyanate was shown.
pH and Concentration Dependent Heavy Metal Uptake by Helianthus tuberosus in Phytoremediation Experiments
Authors: Jablonski Lukasz , Fona Zahra , Rahmi Rizna , Wittig Juliane , Willscher Sabine
Published: December 2015

In the recent time, phytoremediation became an emerging remediation technology due to its low costs and high sustainability. For the remediation of a contaminated mining site with low to medium heavy metal (HM) concentrations, experiments for the phytoextraction and growth behaviour of Helianthus tuberosus were performed. pH and HM concentrations were identified as crucial factors for plant growth and success of phytoremediation. In these experiments, optimal conditions for the plant growth and for the success of phytoremediation were investigated. Plant experiments were carried out in a pH range stepwise from 4.0 – 6.0 and with a combination of different HM (Cd, Cu, Fe, Mn, Ni, Zn, Pb) in three different concentration ranges (slight/ middle/ high); experimental conditions were typical for mining sites with AMD and slight to medium heavy metal impact.
Yields of roots, tubers, leaves and shoots under the appropriate conditions were investigated, and the HM accumulation of different plant parts was analyzed. High accumulation of Fe (up to 1.48 g/kg), Mn (up to 1.68 g/kg) and Zn (up to 853 mg/kg) was measured in roots; shoots accumulated up to 2.6 g/kg Ni, 11.4 g/kg Mn and 6.06g/kg Zn. The accumulation factors for main heavy metals are given in the paper. The further utilization of tubers by fermentation was not inhibited for field site HM concentrations.
As results, H. tuberosus represents a suitable phytoremediation plant species for the phytoextraction of Fe, Mn, Zn, Cd and Ni.
Combined Recovery of Copper and Mitigation of Pollution Potential of a Synthetic Metal-Rich Stream Draining a Copper Mine in Brazil
Authors: Santos Ana Laura , Johnson D. Barrie
Published: December 2015

A low pH sulfate-reducing bioreactor was used to selectively recover copper from synthetic pH 5 mine water draining a copper mine in Brazil, and also to remove other transition metals from solution. The design of the system used meant that a single bioreactor could be used for the process. Over 99% of the copper present was recovered as CuS in an off-line reactor vessel, while other metals (Ni, Co and Zn) were precipitated in the bioreactor vessel.
Analysis of the Microbial Community Associated with a Bioprocess System for Bioremediation of Thiocyanate- and Cyanide-Laden Mine Water Effluents
Authors: Huddy Robert J. , Kantor Rose , van Zyl Wynand , van Hille Robert P. , Banfield Jillian F. , Harrison Susan T.L.
Published: December 2015

Gold extraction by cyanidation from refractory gold ores results in the formation of thiocyanate-and cyanide-contaminated wastewater effluents that must be treated before recycle or discard. Activated sludge processes, such as ASTERTM, can be used for biodegradation of these effluent streams. The destruction of these compounds is catalyzed by a mixed microbial culture, however, very little is known about the community composition and metabolic potential of the thiocyanate-and cyanide-degrading microorganisms within the community. Here we describe our on-going attempts to better understand the key microorganisms, within the ASTERTM bioprocess, that contribute to the destruction of thiocyanate and cyanide, and how this knowledge relates to further process optimisation.
Potential for Conversion of Waste Platinum Group Metals in Road Dust into Biocatalysts for Cracking Heavy Oil
Authors: Murray A.J. , Omajali Jacob , Del Mastio Yara , Hart Abarasi , Wood J. , Macaskie L.E.
Published: December 2015

The oil industry increasingly exploits ‘heavy oils’ which are highly viscous and difficult to extract in a ‘clean’ way. Heat and ‘cracking’ catalysts facilitate extraction e.g. by applying the ‘Toe-to-Heel Air Injection’ (THAI) and ‘Catalytic Process In-Situ’ (CAPRI) techniques. Cracking catalysts include palladium. Use of Pd-catalyst is uneconomic but by using palladium deposited on bacterial cells (in combination with other PMs) a waste can be turned into a valuable product. Road dusts contain precious metals (PMs) which arise from automotive catalytic converters. Once washed from roads the PMs are dispersed to the environment. Model r
oad dust solutions were produced to simulate acid leaching of road dust to solubilise the PMs. Bacteria cannot directly recover PMs from acidic leachate but by lightly depositing Pd(0) ‘seeds’ enzymatically the resulting ‘bio-Pd’-catalyst accumulates PMs from waste model leachate. The bio-catalyst was assessed in the reduction of heavy oil viscosity compared to a commercial catalyst, achieving this reduction with significantly less coke formation, which was not attributable to the biomass component alone.
A Novel Biological Strategy for the Management Industrial Effluents with Simultaneous Recovery of Metal Resource
Authors: Patil Yogesh , Rao Prakash
Published: December 2015

The key objective of present study was to find out a novel and innovative strategy to tackle problem of cyanide and metal-cyanide pollution thereby leading to indirect mitigation of global warming. Studies were performed to test the feasibility of treating aqueous waste containing free cyanide (CN-) and copper-cyanide {Tetracyanocuprate - TCC, [Cu (CN)4]-2} using microalgae Scenedesmus sp. that was isolated by enrichment culture technique under alkaline conditions. Results revealed that microalgae Scenedesmus sp. was capable of detoxifying cyanide and TCC (10-25 mg/l as CN-) with an efficiency of >99% under aerated, static and illuminated conditions within a period of 48-96 h. Process parameters like pH (7-11), temperature (20-45°C), initial cell density (103-106 cells/ml) and varying concentration of cyanide and TCC (5-50 mg/l as CN-) were optimized. Of the total copper ions released during biodegradation of TCC, 37% was adsorbed on the cells, while 67% was accumulated by Scenedesmus cells.
Mining Impacts on the Environment - Water Footprint Assessment of Copper Cathode and Copper Concentrate
Authors: Chan B.K.C. , Xiong Ming Yu , Zhang Guo Ping
Published: December 2015

Water is the source of life and an essential resource for our global economy. It empowers agricultural and industrial production and development, and fosters the nature and ecosystems. With increasing water scarcity, growing population, climate change and extreme weather conditions, together with stricter water regulations, decline in ore grade and increasing controversy on water use between mining operations and local communities, effective governance of shared water resources and protecting water quality is an economic imperative and social responsibility for mining companies. Water Footprint Assessment (WFA) is a holistic methodological framework that allows integrated assessment for operational and supply-chain water use and the associated water footprint sustainability in different sectors at various spatial and temporal scales. This paper presents a WFA for two copper products – copper cathode and copper concentrate produced by Zijin Mining (China) based on the data from 2012 and 2013. The aim of this study is to evaluate the water consumption within the operations and supply chains, to understand the product sustainability and identify water footprint reduction targets to minimize its associated social and environmental impact on natural resources in the catchment. The two copper products were produced from two different processes, hence their different associated water footprints. Evaporation due to the vast area of heap leach pad is the main contribution to the blue water footprint (WF) for copper cathode whereas supply chain WF is negligible. The grey WF is found to be due to total copper concentration in the effluent discharge. This assessment goes beyond water footprint accounting stage and includes the environmental sustainability of the direct water footprint. Opportunities for efficiency improvement across the two processing plants and prevention strategies to reduce impacts on the environment are also discussed. The comprehensive approach makes the WFA unique from other water use assessments and shows its value in water sustainability strategy making.
Theoretical Model of the Structure and the Reaction Mechanisms of Sulfur Oxygenase Reductase in Acidithiobacillus thiooxidans
Authors: Zhang Xian , Yin Hua Qun , Liang Yi Li , Qiu Guan Zhou , Liu Xue Duan
Published: December 2015

Sulfur oxygenase reductase (SOR), which is thought to be an important enzyme involved in sulfur oxidation in many microorganisms, may play a key role in sulfur oxidation in Acidithiobacillusthiooxidans. Draft genome sequence of A. thiooxidans A01 indicated the presence of sulfur oxygenase reductase gene (sor). The complementary DNA fragment was speculated to encode a putative 311-aa full-length protein SOR. Structural analysis of SOR revealed that three cysteines located in the two conserved domains, C32 at V-G-P-K-V-C32 as well as C102 and C105 at C102-X-X-C105, might form the substrate activation and binding site. It was proposed that conserved motif H87-X3-H91-X23-E115 acted as ligands might combine with iron atom to constitute a mononuclear non-heme iron center, catalyzing the oxidation reaction of substrate.
Novel Filamentous Fungi for Metal Removal from Spent Catalyst
Authors: Gómez-Ramírez Marlenne , Plata-González Abel , Fierros-Romero Grisel , Rojas-Avelizapa Norma G.
Published: December 2015

The present study evaluated the ability of organic acids (leaching agent) produced by three filamentous fungi coded as MNSS-AH-5, MV-AH-2 and MV-AH-1 obtained from tailings samples to remove Ni and V from spent catalyst at 16 % (w/v) pulp density. Organic acids were produced in 500 mL Erlenmeyer flasks containing 150 mL of sucrose media where flasks were inoculated with 10% (1x107 conidia/mL) of each fungus and incubated during 6 days at 30°C, 150 rpm. The leaching agent produced by MNSS-AH-5, MV-AH-2 and MV-AH-1 in sucrose media were assayed to remove Ni and V from spent catalyst at 16% (w/v) pulp density during 7 days at 30°C, 150 rpm. At the end of incubation, Ni and V content was evaluated in bio treated catalyst samples by ICP-EOS. Controls containing sucrose media were included in order to evaluate the action of culture media on leaching; all experiments were done in duplicated. Results showed that after 7 days of incubation, the organic acids produced by MNSS-AH-5 were able to leach 2525 mg/Kg of Ni corresponding to 21 %, not significance difference was observed for organic acids of MV-AH-2 and MV-AH-1. In the case of V, all bioleaching treatments presented statistical difference observing a V leaching of 10921.8, 11099.3 and 4757.5 mg/Kg corresponding to 23.5, 24 and 10% for MNSS-AH-5, MV-AH-2 and MV-AH-1 respectively.

Isolate MNSS-AH-5 was identified as Acremonium sp., MV-AH-2 and MV-AH-1 were identified as belonging to genera Penicillium. Based on results, this study shows that leaching agent produced by fungi could be an excellent biological alternative for the removal of Ni and V spent catalyst.
Removal of Cd(II) from Water System Using Novel Biosorbent Derived from Persimmon Fallen Leaves
Authors: Fan Rui Yi , Yi Qing Ping , Zhang Qing Lin , Luo Zheng Rong
Published: December 2015

A biosorbent was prepared by treating the persimmon (Diospyros kaki Thunb.) fallen leaves with sodium hydroxide (NaOH). The NaOH concentration and stirring period for the preparation of the biosorbent were adjusted to optimise the Cd(I) adsorption capacity of the biosorbents. Removal of highly toxic Cadmium metal ions from water system using the optimal biosorbent named ‘NPFL’ was investigated using a mimic industrial column. The result showed that NPFL could remove Cd(II) in large quantities from aqueous solution with coexisting metal ions. The raw material, NPFL and Cd(II) loaded NPFL were characterized by SEM-EDS. The reusability of NPFL was also studied by batch adsorption-desorption test.
An Innovative Model of Managing Silver Metal from Electronic Scrap Using a Combination of Chemical Leaching Followed by Biosorption and Biodegradation
Authors: Patil Yogesh , Bhat Viraja , Rao Prakash
Published: December 2015

This paper attempts to propose an innovative strategy/model for the recovery of precious metal like silver from e-waste by employing combined technologies. Firstly, silver is leached using free cyanide from electronic scrap thereby forming silver-cyanide complex. In the second step, silver-cyanide is removed using biosorption using passiveEicchorniaroots powder biomass. Lastly, the residual silver-cyanide remaining after biosorption is biodegraded using live heterotrophic bacterial consortium. Feasibility study showed that the overall system strategy worked efficiently for the management of e-waste.
Physiological and Genetic Characteristics of Psychrotolerant Acidophile Acidithiobacillus ferrivorans ZB-1 and DX-1
Authors: Zou Kai , Guo Xue , Liang Yi Li , Zhang Xian , Ma Li Yuan , Qiu Guan Zhou , Yin Hua Qun , Liu Xue Duan
Published: December 2015

The draft genome of newly isolatedAcidithiobacillus ferrivoransZB-1 and DX-1 were deciphered to obtain a comprehensive insight into the genetic information and to discover the cellular mechanisms during its high activity in low temperature environment. Genome analysis speculated thatAcidithiobacillus ferrivoransZB-1 and DX-1 could fix carbon dioxide through the Calvin cycle and other central carbon metabolism potentially, and may be able to absorb and utilize nitrate or nitrite in the environment. The related cryophylactic genes (CspD, CspE, Fad and FabG) and gene clusters in fatty acid synthesis were discovered and suggested to play a crucial role in cold resistance.
Microbially Induced Corrosion in Deep Bedrock
Authors: Carpén Leena , Rajala Pauliina , Bomberg Malin
Published: December 2015

This paper covers an overview of recent research of microbially induced corrosion in Fennoscandian terrestrial deep bedrock groundwater environment. The assessment of microbially induced corrosion of metals in the deep bedrock environment has become important in evaluating the long-term safety of disposal of radioactive waste.
Geomicrobiology of Río Tinto, a Model of Interest in Biohydrometallurgy
Authors: Amils Ricardo
Published: December 2015

Río Tinto (Iberian Pyrite Belt, SW Spain) is a natural extreme acidic environmentwith a constant acidic pH and high concentration of toxic heavy metals. The characterization of the Tinto basin performed by our group during more than thirty years has provided evidences on the importance of the iron and sulfur cycles in generating the extreme conditions of theriver and maintaining the high level of prokaryotic and eukaryotic diversity detected on it.It has also proven that the extreme conditions of the Tinto basin are not generated by the long record of mining activities in the area, but the consequence of an underground bioreactor sustained by the massive sulfidic minerals existing in the Iberian Pyrite Belt. To test this hypothesis two drilling projects, MARTE (NASA Ames and Centro de Astrobiología, 2003-2006) and IPBSL (Centro de Astrobiología, 2011-2015) have beenperformed to provide evidences ofchemolithotrophicmicrobial activities operating in thisunderground bioreactor.Considering all the information collected from this natural ARD and AMD model system, its biohydrometallurgical interest is discussed