Changes in the composition of an acid mine drainage microbial community upon successive transfers in medium containing low-grade copper sulfide

The goal of the present work was to perform bioleaching of uranium from low grade ore from Vostok deposit (Republic of Kazakhstan), which was previously subjected to long-term acid leaching. The ore initially contained from 0.15 to 0.20% of uranium in the form of uraninite, but ore samples used in the study contained about 0.05% of uranium, as it was exhausted during acid leaching, and uranium was partially leached. Representative samples of ore were processed in 1 m columns, leach solutions containing 5, 10, 20 g/L of sulfuric acid and bacterial cells (about 104) were percolated through the ore. Leaching was performed at ambient temperature for 70 days. In one of the percolators, the leaching was performed with leaching solution containing 10 g/L of H2SO4, cells of A. ferrooxidans, and 0.5 g/L of formaldehyde. Leaching with the solution containing 5, 10, and 20 g/L of sulfuric acid made it possible to extract 50, 53, and 58% of uranium. Addition of formaldehyde in leach solution led to the decrease in uranium extraction extent down to 37%. Thus, the results of the present work demonstrated that uranium ore exhausted during long-term acid leaching may be successfully subjected to bioleaching, that allows extracting residual quantities of uranium. Leaching rate of uranium from exhausted ore depended on both sulfuric acid concentration and microbial activity of bacteria isolated from acid mine drainage, formed on uranium deposit. In the same time, acid mine drainage may be used as a source of inoculate, to start bioleaching process.

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The spatial assessment of acid mine drainage potential within a low-grade ore dump: the role of preferential flow paths

Environmental Earth Sciences ◽

10.1007/s12665-019-8782-2 ◽

2019 ◽

Vol 79 (1) ◽

Cited By ~ 1

Author(s):

Majid Shahhosseini ◽

Faramarz Doulati Ardejani ◽

Mehdi Amini ◽

Luna Ebrahimi

Keyword(s):

Acid Mine Drainage ◽

Preferential Flow ◽

Mine Drainage ◽

Low Grade ◽

Flow Paths ◽

Spatial Assessment ◽

Acid Mine ◽

Preferential Flow Paths

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A comparison of the acid mine drainage (AMD) neutralization potential of low grade nickel laterite and other alkaline-generating materials

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/778/1/012142 ◽

2020 ◽

Vol 778 ◽

pp. 012142 ◽

Cited By ~ 1

Author(s):

C. Turingan ◽

G. Singson ◽

B. Melchor ◽

R. Alorro ◽

A. Beltran ◽

...

Keyword(s):

Acid Mine Drainage ◽

Mine Drainage ◽

Low Grade ◽

Nickel Laterite ◽

Neutralization Potential ◽

Acid Mine

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Assessing arsenic bioremediation potential of epilithic biofilms affected by acid-mine drainage

10.5194/biofilms9-81 ◽

2020 ◽

Author(s):

Sarah Zecchin ◽

Nicoletta Guerrieri ◽

Evelien Jongepier ◽

Leonardo Scaglioni ◽

Gigliola Borgonovo ◽

...

Keyword(s):

Microbial Community ◽

Acid Mine Drainage ◽

Mine Drainage ◽

Heterotrophic Bacteria ◽

16S Rrna Genes ◽

Rrna Genes ◽

Sampling Point ◽

Epilithic Biofilm ◽

Acid Mine ◽

Epilithic Biofilms

Arsenic is a toxic but naturally abundant metalloid that globally leads to contamination in groundwater and soil, exposing millions of people to cancer and other arsenic-related diseases. In several areas in Northern Italy arsenic in soil and water exceeds law limits (20 mg kg-1 and 10 mg L-1, respectively), due to both the mineralogy of bedrock and former mining activities. The Rio Rosso stream, located in the Anzasca Valley (Piedmont) is heavily affected by an acid mine drainage originated from an abandoned gold mine. Arsenic, together with other heavy metals, is transferred by the stream to the surrounding area. The stream is characterized by the presence of an extensive reddish epilithic biofilm at the opening of the mine and on the whole contaminated waterbed. The aim of this study was to characterize the mechanisms allowing the biotic fraction of this biofilm to cope with extreme arsenic concentrations. The composition and functionality of the microbial communities constituting the epilithic biofilms sampled in the close proximity and downstream the mine were unraveled by 16S rRNA genes and shotgun Illumina sequencing in relation to the extreme physico-chemical parameters. In parallel, autotrophic and heterotrophic microbial populations were characterized in vivo by enrichment cultivation and isolated strains were tested for their ability to perform arsenic redox transformation. Preliminary analyses indicated that the biofilm accumulated arsenic in the order of 6 &#183; 103 mg kg-1, in contrast to 0.14 mg L-1, measured in the surrounding water. The main chemical parameter affecting the composition of the microbial community was the pH, being 2 next to the mine and 6.7 in the downstream sampling point. In both sampling sites iron- and sulfur-cycling microorganisms were retrieved by both cultivation and molecular methods. However, the diversity of the microbial community living next to the mine was significantly lower with respect to the community developed downstream. In the latter, autotrophic Cyanobacteria belonging to the species Tychonema were the dominant taxa. A complete arsenic cycle was shown to occur, with heterotrophic bacteria mainly responsible for arsenate reduction and autotrophic bacteria performing arsenite &#160;oxidation. These observations indicate that the epilithic biofilm living in the Rio Rosso stream represents a peculiar ecosystem where microorganisms cope with metalloid toxicity likely using diverse mechanisms. Such microbial metabolic properties might be exploited in bioremediation strategies applied in arsenic-contaminated environments.

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