Improvement in Metal Recovery from Laterite Tailings by Bioleaching

2009 ◽  
Vol 71-73 ◽  
pp. 489-492 ◽  
Author(s):  
Ianeya Hernández Díaz ◽  
Federico Galizia ◽  
Orquidea Coto ◽  
Edgardo R. Donati
Keyword(s):  
Sulphuric Acid ◽  
Bacterial Growth ◽  
Low Ph ◽  
Metal Recovery ◽  
Pulp Density ◽  
Acidithiobacillus Thiooxidans ◽  
Ph Values ◽  
Technology Process ◽  
High Nickel

In previous studies it has been showed that sulphuric bio-acid is a good leaching agent for laterite tailings. In this work we evaluated nickel and cobalt recoveries from tailings of Caron technology process using sulphuric acid produced by Acidithiobacillus thiooxidans cultures under different conditions. In studies where tailings were initially added to the cultures, high nickel and cobalt recoveries (about 60 % for cobalt and 85-100 % for nickel) were reached after 13 days when low pulp densities (1 % and 2.5 %) of laterite tailings were used. These high recoveries fitted very well with the low pH values measured in these cultures. However, metal recoveries were negligible when higher pulp densities were used. Due to such reason, the performance of pre-cultivation configuration was evaluated; for that laterite tailings were added to the cultures after 24 or 48 hours of bacterial growth. This configuration was very efficient even at high pulp density (like 10 %) reaching recoveries (almost 50 % for cobalt and 80 % for nickel) close to those observed where tailings at low pulp densities were initially added to the cultures.

Recovery of Nickel and Zinc Using Biogenerated Sulphuric Acid

2009 ◽  
Vol 71-73 ◽  
pp. 649-652 ◽  
Author(s):  
Nadia Yagnentkovsky ◽  
M. Viera ◽  
Edgardo R. Donati
Keyword(s):  
Sulphuric Acid ◽  
Ph Value ◽  
Aerobic Oxidation ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Sulphuric Acid Solution ◽  
Pulp Density ◽  
Solid Matrix ◽  
Attractive Alternative ◽  
Acidithiobacillus Thiooxidans

Sludge generated in automotive and related industries often contains heavy metals. Bioleaching is an attractive alternative for the treatment of metal containing solids. Bacteria of the genus Acidithiobacillus are the most important microorganisms applied to metal solubilisation. These microorganisms are able to produce sulphuric acid from the aerobic oxidation of elemental sulphur. The biogenerated sulphuric acid can be applied to the solubilisation of metals from a solid matrix. In this paper we present the results of our experiments aimed at the removal of nickel and zinc from sludge generated in the water treatment plant of an automotive industry. Acidithiobacillus thiooxidans cells were immobilised on sulphur pearls in a column reactor. The effects of sulphur pulp density and the dilution rate on the production of sulphuric acid were studied. In a second stage, sulphuric acid was used to solubilise the nickel and zinc from the sludge. The effects of different sludge pulp densities and initial acid pH were studied. High recoveries of zinc and nickel were obtained when the pH value of the sulphuric acid solution was lower than 2.0 for 1 and 2 % of pulp density.

scholarly journals pH Tolerance in Freshwater Bacterioplankton: Trait Variation of the Community as Measured by Leucine Incorporation

2015 ◽  
Vol 81 (21) ◽  
pp. 7411-7419 ◽  
Author(s):  
Erland Bååth ◽  
Emma Kritzberg
Keyword(s):  
Bacterial Growth ◽  
Low Ph ◽  
Tolerance Index ◽  
Response Curves ◽  
Trait Variation ◽  
High Ph ◽  
Ph Values ◽  
Ph Tolerance ◽  
Community Tolerance

ABSTRACTpH is an important factor determining bacterial community composition in soil and water. We have directly determined the community tolerance (trait variation) to pH in communities from 22 lakes and streams ranging in pH from 4 to 9 using a growth-based method not relying on distinguishing between individual populations. The pH in the water samples was altered to up to 16 pH values, coveringin situpH ± 2.5 U, and the tolerance was assessed by measuring bacterial growth (Leu incorporation) instantaneously after pH adjustment. The resulting unimodal response curves, reflecting community tolerance to pH, were well modeled with a double logistic equation (meanR2= 0.97). The optimal pH for growth (pHopt) among the bacterial communities was closely correlated within situpH, with a slope (0.89 ± 0.099) close to unity. The pH interval, in which growth was ≥90% of that at pHopt, was 1.1 to 3 pH units wide (mean 2.0 pH units). Tolerance response curves of communities originating from circum-neutral pH were symmetrical, whereas in high-pH (8.9) and especially in low-pH (<5.5) waters, asymmetric tolerance curves were found. In low-pH waters, decreasing pH was more detrimental for bacterial growth than increasing pH, with a tendency for the opposite for high-pH waters. A pH tolerance index, using the ratio of growth at only two pH values (pH 4 and 8), was closely related to pHopt(R2= 0.83), allowing for easy determination of pH tolerance during rapid changes in pH.

Development of a Strategy for Selective Metal Recovery from Pregnant Leach Solutions of Kupferschiefer Bioleaching

2015 ◽  
Vol 1130 ◽  
pp. 255-258 ◽  
Author(s):  
Sabrina Hedrich ◽  
Axel Schippers ◽  
D. Barrie Johnson
Keyword(s):  
Ferric Iron ◽  
Low Ph ◽  
Metal Recovery ◽  
Novel Technique ◽  
Ph Values ◽  
Sulfate Removal ◽  
Iron Copper ◽  
Valuable Metals ◽  
Copper Zinc ◽  
High Concentrations

Pregnant leach solutions (PLS) resulting from bioleaching of copper concentrate from Kupferschiefer are characterized by low pH values and high concentrations of mainly ferric iron, copper, zinc and sulfate, as well as significant amounts of nickel and cobalt. In order to recover the valuable metals for further processing, a novel technique that promotes selective metal recovery and sulfate removal from acidic liquors, described in this study, is proposed.

scholarly journals Adaptation of Lactobacillus plantarum IMDO 130201, a Wheat Sourdough Isolate, to Growth in Wheat Sourdough Simulation Medium at Different pH Values through Differential Gene Expression

2011 ◽  
Vol 77 (10) ◽  
pp. 3406-3412 ◽  
Author(s):  
Gino Vrancken ◽  
Luc De Vuyst ◽  
Tom Rimaux ◽  
Joke Allemeersch ◽  
Stefan Weckx
Keyword(s):  
Gene Expression ◽  
Lactobacillus Plantarum ◽  
Differential Gene Expression ◽  
Lipoteichoic Acid ◽  
Low Ph ◽  
Exponential Growth Phase ◽  
Cellular Mechanisms ◽  
Content Type ◽  
Ph Values ◽  
Differential Gene

ABSTRACTSourdough is a very competitive and challenging environment for microorganisms. Usually, a stable microbiota composed of lactic acid bacteria (LAB) and yeasts dominates this ecosystem. Although sourdough is rich in carbohydrates, thus providing an ideal environment for microorganisms to grow, its low pH presents a particular challenge. The nature of the adaptation to this low pH was investigated forLactobacillus plantarumIMDO 130201, an isolate from a laboratory wheat sourdough fermentation. Batch fermentations were carried out in wheat sourdough simulation medium, and total RNA was isolated from mid-exponential-growth-phase cultures, followed by differential gene expression analysis using a LAB functional gene microarray. At low pH values, an increased expression of genes involved in peptide and amino acid metabolism was found as well as that of genes involved in plantaricin production and lipoteichoic acid biosynthesis. The results highlight cellular mechanisms that allowL. plantarumto function at a low environmental pH.

scholarly journals Mechanism of Coagulation of Humic Acid in Presence of Metal Ion Coagulants at Low pH Values

1970 ◽  
Vol 73 (5) ◽  
pp. 874-878 ◽  
Author(s):  
Takao YOTSUYANAGI ◽  
Katsumi GOTO ◽  
Masaichi NAGAYAMA
Keyword(s):  
Humic Acid ◽  
Metal Ion ◽  
Low Ph ◽  
Ph Values

scholarly journals Histidine-Rich Glycoprotein Inhibits HIV-1 Infection in a pH-Dependent Manner

2018 ◽  
Vol 93 (4) ◽  
Author(s):  
Ezequiel Dantas ◽  
Fernando Erra Díaz ◽  
Pehuén Pereyra Gerber ◽  
Augusto Varese ◽  
Diana Alicia Jerusalinsky ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Respiratory Syncytial Virus ◽  
Herpes Simplex ◽  
Low Ph ◽  
Vaginal Mucosa ◽  
Ph Values ◽  
Syncytial Virus ◽  
Simplex Virus ◽  
Herpes Simplex Virus 2 ◽  
Hiv 1

ABSTRACTHistidine-rich glycoprotein (HRG) is an abundant plasma protein with a multidomain structure, allowing its interaction with many ligands, including phospholipids, plasminogen, fibrinogen, IgG antibodies, and heparan sulfate. HRG has been shown to regulate different biological responses, such as angiogenesis, coagulation, and fibrinolysis. Here, we found that HRG almost completely abrogated the infection of Ghost cells, Jurkat cells, CD4+T cells, and macrophages by HIV-1 at a low pH (range, 6.5 to 5.5) but not at a neutral pH. HRG was shown to interact with the heparan sulfate expressed by target cells, inhibiting an early postbinding step associated with HIV-1 infection. More importantly, by acting on the viral particle itself, HRG induced a deleterious effect, which reduces viral infectivity. Because cervicovaginal secretions in healthy women show low pH values, even after semen deposition, our observations suggest that HRG might represent a constitutive defense mechanism in the vaginal mucosa. Of note, low pH also enabled HRG to inhibit the infection of HEp-2 cells and Vero cells by respiratory syncytial virus (RSV) and herpes simplex virus 2 (HSV-2), respectively, suggesting that HRG might display broad antiviral activity under acidic conditions.IMPORTANCEVaginal intercourse represents a high-risk route for HIV-1 transmission. The efficiency of male-to-female HIV-1 transmission has been estimated to be 1 in every 1,000 episodes of sexual intercourse, reflecting the high degree of protection conferred by the genital mucosa. However, the contribution of different host factors to the protection against HIV-1 at mucosal surfaces remains poorly defined. Here, we report for the first time that acidic values of pH enable the plasma protein histidine-rich glycoprotein (HRG) to strongly inhibit HIV-1 infection. Because cervicovaginal secretions usually show low pH values, our observations suggest that HRG might represent a constitutive antiviral mechanism in the vaginal mucosa. Interestingly, infection by other viruses, such as respiratory syncytial virus and herpes simplex virus 2, was also markedly inhibited by HRG at low pH values, suggesting that extracellular acidosis enables HRG to display broad antiviral activity.

scholarly journals An Investigation of the Bacterial Influence of Acidithiobacillus Thiooxidans on Concrete Composites

2018 ◽  
Vol 45 ◽  
pp. 00021 ◽  
Author(s):  
Vlasta Ondrejka Harbulakova ◽  
Adriana Estokova ◽  
Alena Luptakova
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Acidithiobacillus Thiooxidans ◽  
Chemical Plants ◽  
Biological Factors ◽  
Sewer Pipes ◽  
Ph Values ◽  
Industrial Structures ◽  
Time Period ◽  
Microbial Environment

Vegetation and microorganisms present the biological factors that deteriorate concrete. These problems are very visible in places like sewage, underground and hydraulic structures, chemical plants, industrial structures, liquid-containing structures, agricultural structures or marine environments. The most significant biodeteriogens are the sulphur-oxidising bacteria Acidithiobacillus thiooxidans (A. thiooxidans) and the sulphatereducing bacteria (Desulfovibrio spp.) that are responsible for the so-called sulphuretum consortium. Microorganisms that produce sulphuric acid accelerate the deterioration of concrete sewer pipes in a process termed Microbially Induced Concrete Corrosion (MIC). The paper considers the assessment of the release of calcium and silicon from concrete composites with and without coal fly ash by sulphur-oxidizing bacteria. The concrete mixture contained coal fly ash as 5 wt. % and wt. 10 % cement replacement. Prepared composites were exposed to an aggressive microbial environment under laboratory conditions for 3 months. The pH values were measured and studied during this time period. A different resistance against MIC was observed for the concrete composites of different compositions. The highest amount of calcium leached-out from the concrete was in the case of the composites where 10 % cement was replaced by fly ash.

scholarly journals Effect of water temperature and pH on the concentration and time of ozone saturation

2018 ◽  
Vol 21 (0) ◽  
Author(s):  
Melicia Cintia Galdeano ◽  
Allan Eduardo Wilhelm ◽  
Isabella Borges Goulart ◽  
Renata Valeriano Tonon ◽  
Otniel Freitas-Silva ◽  
...  
Keyword(s):  
Water Temperature ◽  
Molecular Oxygen ◽  
Half Life ◽  
Low Ph ◽  
Ozone Content ◽  
Effect Of Temperature ◽  
Saturation Time ◽  
Gas Concentration ◽  
Ph Values ◽  
Effect Of Water

Abstract Ozone has been used for many years to disinfect water due to its oxidizing potential. Since it decomposes quickly into molecular oxygen, leaving no residue, it has important advantages for use. The decomposition of ozone is affected by the temperature and pH of the medium, low pH values and temperatures increasing its half-life, which can result in more efficient disinfection. With the objective of increasing the effectiveness of ozonation, this study investigated the effect of temperature (8 ºC and 25 °C) and pH (3.0 and 6.0) of the water on the saturation time and gas concentration, employing two initial gas concentrations (13.3 and 22.3 mg L-1). The concentration of ozone saturation increased as the temperature and pH of the medium decreased, as also with the higher initial gas concentration ( C0). The highest saturation concentrations were obtained at pH 3.0 and 8 °C (4.50 and 8.03 mg L-1 with C0 of 13.3 and 22.3 mg L-1, respectively). This higher ozone content could result in greater decontamination efficiency of the food products washed with this water.

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