Bioleaching of heavy metals from dewatered sludge by Acidithiobacillus ferrooxidans

The feasibility of bioleaching for removal of heavy metals from dewatered sewage sludge using an iron‐oxidizing bacterium Acidithiobacillus ferrooxidans was investigated. The influence of seven process parameters including cell adaptation, total amount and particle size of the sludge, initial concentrations of Fe²⁺ and At ferrooxidans, and addition of inorganic nutrients and sulfur were evaluated in terms of the solubilization of Zn, Cu and Cr. When sludge‐adapted cells, addition of inorganic nutrients and lower sludge content were involved, higher yields of metal extraction were obtained. However, higher initial concentrations of At ferrooxidans and Fe²⁺, fine particle size of the sludge and S addition did not improve the metals' solubilization during an experimental period of 7 days. As a result of a long‐term (40 days) bioleaching experiment, 42% of Zn (1300–1648 mg kg^?1), 39% of Cu (613–774 mg kg^?1) and 10% of Cr (37–44 mg kg^?1) in the sludge were leached into the solution. The results indicate that a bioleaching process conducted under operationally optimal conditions can be effectively employed for the removal of heavy metals from sewage sludge before land application. Copyright © 2005 Society of Chemical Industry     

氧化亚铁硫杆菌浸矿体系中黄铁矿的电化学行为(英文)

运用循环伏安、稳态极化扫描和交流阻抗等电化学测试方法,研究黄铁矿在氧化亚铁硫杆菌浸矿体系和无菌酸性体系下的电化学氧化机理。结果表明,在无菌和A.ferrooxidans菌存在的条件下,黄铁矿的氧化反应分为两步:第一步是黄铁矿氧化生成元素S;第二步是元素S被氧化生成SO42-。加入A.ferrooxidans后黄铁矿的氧化机理没有发生改变,但是氧化速度加快。随着黄铁矿与A.ferrooxidans作用时间的延长,极化电流密度增加,黄铁矿表面钝化膜溶解的点蚀电位降低。在细菌存在的条件下,电极的阻抗值下降,表明微生物的存在加速了黄铁矿电极的腐蚀作用,有利于黄铁矿的氧化溶解。     

氧化亚铁硫杆菌的固定化及动力学研究

以沸石为填料用吸附法构建了氧化亚铁硫杆菌固定化细胞生物反应器，考查了空气流量、液体流量对固定化效果的影响。在温度相同，培养基的pH=1．6，Fe^2＋浓度为8g／L左右的条件下，固定化细胞在Fe^2＋氧化率达95．36％时的氧化速率高达1．10/L·h，其Fe^2＋的氧化速率将近是游离细胞的18倍。固定化细胞生物反应器的动力学研究表明，氧化亚铁硫杆菌固定化细胞氧化Fe^2＋反应符合一级反应，其反应速率常数k为0．37h^-1。     

氧化亚铁硫杆菌最佳生长条件的初步探索

氧化亚铁硫杆菌生长活性影响因素有很多，其中主要的是温度、pH、培养基的量以及接种量等。用比浊法以及二价铁离子的变化为指标，对氧化亚铁硫杆菌的生长条件进行初步研究，得出其最佳生长条件为：温度28℃左右，初始pH为2．3左右，培养基装量为50～100mL／250mL。接种量为10％。     

Bioflotation of pyrite with Thiobacillus ferrooxidans

Bioflotation of pyrite with bacteria Thiobacillus ferrooxidans in the presence or absence of potassium ethyl xanthate was studied on a pure pyrite through microflotation and electrophoretic light scattering measurements. The experimental results showed that in the absence of xanthate, pyrite flotation is slightly enhanced by Thiobacillusferrooxidans. However, with xanthate as a collector, pyrite flotation is strongly depressed after being exposed to the bacteria. The longer is the time when the pyrite is exposed to the bacteria, the stronger the depression is. The mechanism of the depression might be due to the formation of the biofilms of Thiobacillus ferrooxidans on pyrite surfaces, preventing the adsorption of xanthate on pyrite surfaces in the form of dixanthogen or xanthate ions.     

Quorum sensing detected by atomic force microscopy imaging of corrals surrounding multicellular arrangement of bacteria

Connectivity of the glycocalyx covering of small communities of Acidithiobacillus ferrooxidans bacteria deposited on hydrophilic mica plates was imaged by atomic force microscopy. When part of the coverage was removed by water rinsing, an insoluble structure formed by corrals surrounding each individual bacterium was observed. A collective ring structure with clustered bacteria (>or=3) was observed, which indicates that the bacteria perceived the neighborhood in order to grow a protective structure that results in smaller production of exopolysaccharides material. The most surprising aspect of these collective corral structures was that they occur at a low bacterial cell density. The deposited layers were also analyzed by confocal Raman microscopy and shown to contain polysaccharides, protein, and glucoronic acid.     

耐高矿化度浸矿菌的驯化及浸铀效果

从721铀矿石样中分离出的一株氧化亚铁钩端螺旋菌(Leptospirillums ferrooxidans)与氧化亚铁硫杆菌(Thiobacillus ferrooxidans)的混合菌株,经不同条件的驯化及紫外线诱变处理后,可在高矿化度(M>50g/L)、低pH(pH=1.4)的铀矿石酸化液中良好生长。实验室槽浸实验表明,这一混合菌株对低pH、高矿化度的浸出体系具有良好的适应性,仅用7天时间,渣计浸出率达90.06%,浸出过程中未出现铁损失。     

Adsorption characteristics of thiobacillus ferrooxidans on surface of sulfide minerals

1INTRODUCTION Thefeatureofmineralsurfaceismodifiedlike thecellsurfacebyfixingbacteriaonitssurface whilethefeatureofcellsurfaceisdeterminedbyits livingcondition[1].Thecomponentofbacterial surfaceplaysanimportantroleinthebacterialat tachmentonminerals[2,3].Itisprovedthatcell wallandoutermembraneareinvolvedintheadhe sionbetweenmineralsandmicrobes,whilethein nermembraneandotherorganelleshardlyhaveany influenceonthisprocess.Thesephysiological structuresofbacteria,especiallytheoutermem brane,af…     

Homology modeling and evolutionary trace analysis of superoxide dismutase from extremophile Acidithiobacillusferrooxidans

The gene sod in Acidithiobacillus ferrooxidans may play a crucial role in its tolerance to the extremely acidic, toxic and oxidative environment of bioleaching. For insight into the anti-toxic mechanism of the bacteria, a three-dimensional (3D) molecular structure of the protein encoded by this gene was built by homology modeling techniques, refined by molecular dynamics simulations, assessed by PROFILE-3D and PROSTAT programs and its key residues were further detected by evolutionary trace analysis. Through these procedures, some trace residues were identified and spatially clustered. Among them, the residues of Asn38, Gly103 and Glu161 are randomly scattered throughout the mapped structure; interestingly, the other residues are all distinctly clustered in a subgroup near Fe atom. From these results, this gene can be confirmed at 3D level to encode the Fe-depending superoxide dismutase and subsequently play an anti-toxic role. Furthermore, the detected key residues around Fe binding site can be conjectured to be directly responsible for Fe binding and catalytic function.     

Preparation ofjarosite by Acidithiobacillus ferrooxidans oxidation

The formation of jarosite in the presence of Acidithiobacillus ferrooxidans (A. ferrooxidans) was researched to ascertain the conditions of producing minimum precipitation. The effects of salt concentration and pH on the characteristics of jarosite formed in K2SO4/(NH4)2SO4-FeSO4 inorganic salt solution and 9K medium were studied by using the measurements of scanning electron microscope, X-ray diffraction, Fourierism transform infrared analysis, thermogravity/differential thermogravity analysis and particle size analysis to evaluate the product. The results indicate that the formation of jarosite begins when A. ferrooxidans reaches logarithmic growth phase in 9K medium, and a higher pH value is beneficial to the formation of jarosite. The jarosite formed in 9K medium has smaller and more concentrative particle size and smoother surface than that formed in inorganic salt solution.