Sulfur-oxidizing Bacteria Acidithiobacillus Thiooxidans Research Articles

Cement Composites Biodeterioration by Acidithiobacillus Thiooxidans

The focus of this work was to study the biodeterioration of special cement composites by sulfur-oxidizing bacteria Acidithiobacillus thiooxidans. The laboratory prepared cement composites that contained the selected additives - silica fume (a secondary raw material) and zeolite (a natural raw material), as partial replacements for the binder. The tests were carried out in laboratory conditions. During the experiments, changes to the pH values and the Ca and Si concentrations were observed in the liquid phases. Based on the achieved results, it can be concluded that concrete composites with partial replacement of the binder by silica fume and zeolite have a higher resistance to biogenic sulfuric acid.

Urban biomining: lithium recovery from spent batteries through multi-step bioprocesses

Multi-step design to evaluate the bio-recovery of lithium from spent batteries was studied. The first step consisted of lithium extraction from spent batteries, using bacterial and fungal acid extrolites. The second step explored lithium recovery in the form of carbonate salts by using MICP (Microbial Induced Carbonate Precipitation) bacteria from Sporosarcina species. For lithium extraction (Step 1) sulfuric acid produced by sulphur oxidizing bacteria Acidithiobacillus thiooxidans was evaluated for its capacity to leach lithium. Extraction with biogenic sulfuric acid and with fungal bio- produ-cts (from Aspergillus sp. and Simplicillum sp. isolated at our facilities) were compared with commercial sulfuric acid. For biorecovery processes (Step 2), two type strains of Sporosarcina sp. were tested due to their capacity to precipitate lithium carbonate. Results showed fungal bioextracts gave a lithium leaching yield close to 60% and a global recovery yield of 27%. These observations are reported for the first time and lay the foundations for continuing the study and scaling up of this combined process for lithium recovery.

Pharmaceutical blister waste recycling using biogenic sulfuric acid: Effect of sulfur source and blister material on bioleaching efficiency

Several thousand tons of plastic are produced globally for pharmaceutical blister packages every year, leading to an expected consumption of over 2.8 million tons by 2026. Comprising a complex multilayer structure, blisters cannot be recycled in conventional recycling processes, leading to a loss of aluminium and valuable polymers during incineration and landfilling. As a promising secondary source of aluminium, new recycling strategies need to be developed to selectively separate the different layers. In this study, three types of blister packaging materials consisting of 13–68% (w/w) aluminium were investigated regarding aluminium and polymer recovery by using biogenic sulfuric acid for bioleaching. Waste elemental sulfur from biogas desulfurisation was assessed for biogenic sulfuric acid production by the two sulfur-oxidizing bacteria Acidithiobacillus thiooxidans and Acidithiobacillus caldus and compared to commercial elemental sulfur. For biogenic sulfur, higher sulfate production yield (320 mM), lower pH-value (pH = 0.56) and complete sulfur oxidation within 14 days was observed when compared to commercial sulfur. Application of a more concentrated biogenic acid (pH = 0.22) led to more effective and complete (∼100%) aluminium bioleaching up to 7.5% (w/v) blister waste within 7–9 days of incubation compared to 83% and 63% chemical leaching efficiency of transparent and white blisters using commercial sulfuric acid at the same pH, respectively. In addition, the plastic fraction after bioleaching was characterized and tested regarding re-processability. Results showed that sulfur from a biological origin can be oxidized faster by bacteria and biogenic acid is more effective in aluminium bioleaching compared to commercial sulfuric acid. Furthermore, results indicated that the plastic material is suitable for re-processing making this process an economically and environmentally friendly treatment option.

Innovative bio-acid leaching method for high recovery of critical metals from end-of-life light emitting diodes

The main objective of this work is to introduce a new green recycling process for recovering valuable metals from electronic waste. One of the fastest-growing electronic waste streams is end-of-life light emitting diodes (LEDs). Due to environmental risk and a worldwide shortage of metals, recycling and recovering their valuable metal is an urgent task. In this study, an innovative bio-hydrometallurgical method for the extraction of valuable metals from end-of-life LED lamps is proposed. The present study evaluated a direct multi-step regulation strategy of waste content to enhance the bio-acid leaching of LED at a high pulp density (40 g/L) using a culture of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans (A. thiooxidans). Through a step-wise feeding strategy (10 g/d), the extraction of the metal was further improved due to balancing of A. thiooxidans population and stabilization of pH, ORP, and sulfuric acid concentration in the bioleaching solution. By comparing the results of multi-step and one-stage contact bioleaching, with multi-step contact bioleaching, Cu, Ni, and Ga extraction yields increased from 67%, 92%, and 39% to 100%, 100%, and 75%. Furthermore, this study demonstrates that the presence/addition of EPS did not only adsorb metal ions but also increased diffusion barriers, thus diminishing metal ion transfer from LED into bioleaching solution for an extended period of time. The multi-step non-contact bio-acid leaching method enhanced strategic critical element leaching yields to 100% from end-of-life LEDs. The final product, enriched in Au and Ag, could be used as a secondary source of precious metals.

The Ability of Slag-Portland Cement Composites to Withstand Aggressive Environment

The use of separately ground blast-furnace slag, added at the mixer as a replacement for a portion of the Portland cement, has gained increasing acceptance in recent years. The effects of partial replacement of Portland cement with ground slag on the properties of hardened concrete have been extensively investigated and reported. Both laboratory testing and field experience have shown that properly proportioned slag-Portland cement concretes have the improved resistance to sulfates and seawater compared to regular Portland mixes. The paper is focused on the effects of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans on concrete mixtures with addition of ground granulated blast furnace slag compared to mixture without any additives. The concrete specimens with 65 and 75 % wt. addition of antimicrobial activated granulated blast furnace slag as durability increasing factor as well as without any addition were investigated in laboratory during the nine 7-day cycles. A laboratory study was conducted to comparison the performance of concrete samples in terms of a concrete deterioration influenced by the leaching of calcium and silicon compounds from the cement matrix. The changes in the elemental concentrations of calcium and silicon ions in leachates were measured by using X – ray fluorescence method. The pH values were measured and evaluated after each cycle. The concrete specimen with 65 % wt. addition of antimicrobial activated granulated blast furnace slag was found to have the best leaching performance of calcium ions than other samples. The final concentration of Si ions in leachate of concrete specimen with 75 % wt. addition of antimicrobial activated granulated blast furnace slag affected with bacteria Acidithiobacillus thiooxidans (4.614 mg/g of concrete sample) was observed to be 1.263 times lower than reference sample without any additives. The higher resistance of concrete samples with the addition of antimicrobial activated granulated blast furnace slag to the aggressive environment was confirmed.

Durability Performance of Cement Composites Containing Ground Granulated Blast Furnace Slag

The hydraulic properties of granulated blast-furnace slags have been studied for nearly 200 years, and use of slag in mortars and concretes dates back more than a hundred years. The use of ground blast furnace slag, added as a replacement for a portion of the portland cement, has gained increasing acceptance in recent years. The effects of sulphur-oxidizing bacteria Acidithiobacillusthiooxidans on concrete mixture with addition of ground granulated blast furnace slag compared to mixture without any additives were investigated in laboratory over a period of 91 days. A laboratory study was conducted to comparison the performance of concrete samples in terms of a concrete deterioration influenced by the leaching of calcium compounds from the cement matrix. The changes in the elemental concentrations of calcium ions in leachates were measured by using X – ray fluorescence method. Experimental studies confirmed: bacteria Acidithiobacillus thiooxidans caused much intensive calcium release from the concrete matrices into the solution; the higher resistance of concrete mixture with 65 % wt. slag addition was not confirmed.

Bio-Corrosion of Fibrous Cement Boards and Cement Composites

The paper deals with the comparative study of bio-corrosion of fibrous cement boards and Portland cement composites. Fibre-cement flat boards are widely used materials in the Slovak Republic for exterior and interior cladding, as fibre-cement slates for roofing and cladding and as fibre-cement corrugated sheets for roofing and cladding. Bio-corrosion of studied materials has been simulated in laboratory conditions during 80 days. Effect of sulphur-oxidizing bacteria Acidithiobacillusthiooxidans on the specimens was investigated. The bio-deterioration processes have been manifested by leaching of main cement components as well as by surface changes. The calcium and silicon contents in leachates were evaluated during the experiments using X – ray fluorescence method (XRF). Concluding the results of the concrete’s biodeteriogens influence on the analyzed samples (fiber boards and cement composites) more extensive leaching of calcium ions from the cement matrix was confirmed as assumed by bacteria influence when compared to the abiotic environment. Mixture of white compounds on the samples surface was identified by SEM microscopy and XRD analysis as sulphate products (ettringite, thaumasite, gypsum). Shift of pH of liquid media to alkaline region up to 7.2 due to alkaline products leaching were noticed for all studied samples.

Evolution of biofilms during the colonization process of pyrite by Acidithiobacillus thiooxidans

We have applied epifluorescence principles, atomic force microscopy, and Raman studies to the analysis of the colonization process of pyrite (FeS(2)) by sulfuroxidizing bacteria Acidithiobacillus thiooxidans after 1, 15, 24, and 72 h. For the stages examined, we present results comprising the evolution of biofilms, speciation of S (n) (2-) /S(0) species, adhesion forces of attached cells, production and secretion of extracellular polymeric substances (EPS), and its biochemical composition. After 1 h, highly dispersed attached cells in the surface of the mineral were observed. The results suggest initial non-covalent, weak interactions (e.g., van der Waal's, hydrophobic interactions), mediating an irreversible binding mechanism to electrooxidized massive pyrite electrode (eMPE), wherein the initial production of EPS by individual cells is determinant. The mineral surface reached its maximum cell cover between 15 to 24 h. Longer biooxidation times resulted in the progressive biofilm reduction on the mineral surface. Quantification of attached cell adhesion forces indicated a strong initial mechanism (8.4 nN), whereas subsequent stages of mineral colonization indicated stability of biofilms and of the adhesion force to an average of 4.2 nN. A variable EPS (polysaccharides, lipids, and proteins) secretion at all stages was found; thus, different architectural conformation of the biofilms was observed during 120 h. The main EPS produced were lipopolysaccharides which may increase the hydrophobicity of A. thiooxidans biofilms. The highest amount of lipopolysaccharides occurred between 15-72 h. In contrast with abiotic surfaces, the progressive depletion of S (n) (2-) /S(0) was observed on biotic eMPE surfaces, indicating consumption of surface sulfur species. All observations indicated a dynamic biooxidation mechanism of pyrite by A. thiooxidans, where the biofilms stability and composition seems to occur independently from surface sulfur species depletion.

Fractionation behavior of heavy metals in soil during bioleaching with Acidithiobacillus thiooxidans

The effects of bioleaching on the fractionation of soil heavy metals were investigated in this study. Bioleaching of heavy metals from contaminated soil was carried out in shake flask experiments. Acidophilic sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from soil was used for bioleaching. Bioleaching resulted in removal of heavy metals at higher levels. Variations in the binding forms of heavy metals before, during and after bioleaching were evaluated. It was noticed that bioleaching affected the binding forms of all the heavy metals present in the soil. The major contaminant chromium bound mainly to the fractions of soil which are not very reactive (organic and residual fractions) also showed good removal efficiency. Bioleaching influenced the fractionation of metals in soil after treatment and most of the remnant heavy metals were bound either to residual fraction or to other not easily mobile fractions of soil. The results of this study indicated that the bioleaching process can be useful for efficient removal of heavy metals from soil. Further, the soil with remnant metals can be disposed off safely.

Liquid-nitrogen cryopreservation of three kinds of autotrophicbioleaching bacteria

Three kinds of autotrophic bioleaching bacteria strains, including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans ( A. ferrooxidans), mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans ( A. thiooxidans), and moderately thermophilic sulfur-oxidizing bacteria Acidianus brierleyi, were cryopreserved in liquid nitrogen and their ferrous ion- or sulfur-oxidizing activities were investigated and compared with the original ones. The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation. Glycerin was used as cryoprotective agent. In conclusion, liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.

Changes in nutrient profile of soil subjected to bioleaching for removal of heavy metals using Acidithiobacillus thiooxidans

Studies were carried out to assess changes in nitrogen, phosphorus and potassium contents in soil during bioleaching of heavy metals from soil contaminated by tannery effluents. Indigenous sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from the contaminated soil were used for bioremediation. Solubilization efficiency of chromium, cadmium, copper and zinc from soil was 88, 93, 92 and 97%, respectively. However, loss of nitrogen, phosphorus and potassium from the soil was 30, 70 and 68%, respectively. These findings indicate that despite its high potential for removal of heavy metals from contaminated soils, bioleaching results in undesirable dissolution/loss of essential plant nutrients. This aspect warrants urgent attention and detailed studies to evaluate the appropriateness of the technique for field application.

Growth Inhibition by Tungsten in the Sulfur-Oxidizing BacteriumAcidithiobacillus thiooxidans

Growth of five strains of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans, including strain NB1-3, was inhibited completely by 50 microM of sodium tungstate (Na(2)WO(4)). When the cells of NB1-3 were incubated in 0.1 M beta-alanine-SO(4)(2-) buffer (pH 3.0) with 100 microM Na(2)WO(4) for 1 h, the amount of tungsten bound to the cells was 33 microg/mg protein. Approximately 10 times more tungsten was bound to the cells at pH 3.0 than at pH 7.0. The tungsten binding to NB1-3 cells was inhibited by oxyanions such as sodium molybdenum and ammonium vanadate. The activities of enzymes involved in elemental sulfur oxidation of NB1-3 cells such as sulfur oxidase, sulfur dioxygenase, and sulfite oxidase were strongly inhibited by Na(2)WO(4). These results indicate that tungsten binds to NB1-3 cells and inhibits the sulfur oxidation enzyme system of the cells, and as a result, inhibits cell growth. When portland cement bars supplemented with 0.075% metal nickel and with 0.075% metal nickel and 0.075% calcium tungstate were exposed to the atmosphere of a sewage treatment plant containing 28 ppm of H(2)S for 2 years, the weight loss of the portland cement bar with metal nickel and calcium tungstate was much lower than the cement bar containing 0.075% metal nickel.