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Rubinos DA, Spagnoli G. Assessment of red mud as sorptive landfill liner for the retention of arsenic (V). JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 232:271-285. [PMID: 30481641 DOI: 10.1016/j.jenvman.2018.09.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 09/08/2018] [Accepted: 09/11/2018] [Indexed: 06/09/2023]
Abstract
The sorption of AsV on red mud (bauxite residue), produced in the ALCOA-San Cibrao factory (Spain), was assessed in view of its potential use as sorptive liner of landfills for the attenuation of As-rich leachates. The operating parameters evaluated, using batch-type procedures, comprised the effects of time, solution pH, AsV concentration (sorption isotherm) and presence of phosphate on the AsV sorption. The results showed that the red mud efficiently sorbed AsV. The sorption was fast, with a major fraction of initial AsV being removed in a few minutes or hours of contact, depending on AsV concentration. The kinetic process was well described by the pseudo-second order equation, which points to chemisorption is involved, whereas surface (film) diffusion chiefly governs the rate of AsV sorption for the red mud system. Sorption of AsV was strongly pH-dependent. Maximum removal (>98%) was observed at slightly acidic pH (pHmax = 5.5-6), while AsV sorption considerably decreased at both highly acidic and alkaline pH. The percentages of sorbed AsV decreased with the increasing solution AsV concentration, and the AsV sorption capacity (up to 43.5 mmol/kg) of the red mud was higher (∼4 -fold) at pH ∼6 than at pH ∼9.2 (natural pH of the red mud). The presence of P at equimolar or 1:10 As/P molar ratios reduced AsV sorption by ∼20% and 30%, respectively. Simulations of AsV migration taking into account the effects of dispersion and diffusion through an hypothetical red mud liner, using the sorption parameters and the geotechnical-hydraulic conductivity characteristics of the RM, predicted a deeper migration of AsV in the liner at pH∼9.2 than at pH∼6 and a minimum thickness of ∼90 cm and ∼20 cm, respectively, for a RM liner to decrease the solution AsV concentration from highly toxic 1 mM to a safe <0.133 μM (<10 μg/L) level, after a 35-years period.
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Affiliation(s)
- David A Rubinos
- Freelance Researcher & Consultant, Reboiras 39, 15981 A Coruña, Spain.
| | - Giovanni Spagnoli
- BASF Construction Solutions GmbH, Dr.-Albert-Frank-Straße 32, 83308 Trostberg, Germany.
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The Arsenic Detoxification System in Corynebacteria: Basis and Application for Bioremediation and Redox Control. ADVANCES IN APPLIED MICROBIOLOGY 2017; 99:103-137. [PMID: 28438267 DOI: 10.1016/bs.aambs.2017.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Arsenic (As) is widespread in the environment and highly toxic. It has been released by volcanic and anthropogenic activities and causes serious health problems worldwide. To survive arsenic-rich environments, soil and saprophytic microorganisms have developed molecular detoxification mechanisms to survive arsenic-rich environments, mainly by the enzymatic conversion of inorganic arsenate (AsV) to arsenite (AsIII) by arsenate reductases, which is then extruded by arsenite permeases. One of these Gram-positive bacteria, Corynebacterium glutamicum, the workhorse of biotechnological research, is also resistant to arsenic. To sanitize contaminated soils and waters, C. glutamicum strains were modified to work as arsenic "biocontainers." Two chromosomally encoded ars operons (ars1 and ars2) are responsible for As resistance. The genes within these operons encode for metalloregulatory proteins (ArsR1/R2), arsenite permeases (Acr3-1/-2), and arsenate reductases (ArsC1/C2/C1'). ArsC1/C2 arsenate reductases are coupled to the low molecular weight thiol mycothiol (MSH) and to the recently discovered mycoredoxin-1 (Mrx-1) present in most Actinobacteria. This MSH/Mrx-1 redox system protects cells against different forms of stress, including reactive oxygen species (ROS), metals, and antibiotics. ROS can modify functional sulfur cysteines by oxidizing the thiol (-SH) to a sulfenic acid (-SOH). These oxidation-sensitive protein cysteine thiols are redox regulated by the MSH/Mrx-1 couple in Corynebacterium and Mycobacterium. In summary, the molecular mechanisms involved in arsenic resistance system in C. glutamicum have paved the way for understanding the cellular response against oxidative stress in Actinobacteria.
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Rubinos DA, Barral MT. Use of red mud (bauxite residue) for the retention of aqueous inorganic mercury(II). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:17550-17568. [PMID: 26141977 DOI: 10.1007/s11356-015-4901-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/15/2015] [Indexed: 06/04/2023]
Abstract
The effectiveness of the oxide-rich residue from bauxite refining (red mud) to remove inorganic Hg(II) from aqueous solutions was assessed. The aspects studied comprised the kinetics of the process (t = 1 min-24 h), the effect of pH (3.5-11.5), the interacting effect between salt concentration (0.01-1 M NaNO3) and pH and the Hg(II) sorption isotherm. Hg leaching from spent red mud was evaluated using the toxicity characteristics leaching procedure (TCLP) method. The sorption of Hg(II) onto red mud was very fast, with most of Hg(II) (97.0-99.7%) being removed from 0.5-50 μM Hg solutions in few minutes. The kinetic process was best described by Ho's pseudo-second order equation, pointing to chemisorption as the rate controlling step. Hg(II) sorption efficiency was very high (% removal between 93.9 and 99.8%) within all the studied pH range (3.5-11.5) and added Hg concentrations (5 and 50 μM), being optimal at pH 5-8 and decreasing slightly at both lowest and highest pH. The effect of background electrolyte concentration suggests specific sorption as the main interaction mechanism between Hg(II) and red mud, but the increasing non-sorbed Hg concentrations at low and high pH for higher electrolyte concentrations also revealed the contribution of an electrostatic component to the process. The sorption isotherm showed the characteristic shape of high affinity sorbents, and it was better described by the Redlich-Peterson and Freundlich equations, which are models that assume sorbent heterogeneity and involvement of more than one mechanism. The estimated Hg(II) sorption capacity from the Langmuir equation (q m ~9 mmol/kg) was comparable to those of some inorganic commercial sorbents but lower than most bio- or specifically designed sorbents. The leachability of retained Hg(II) from spent red mud (0.02, 0.25 and 2.42 mmol Hg/kg sorbed concentration) was low (0.28, 1.15 and 2.23 μmol/kg, respectively) and accounted for 1.2, 0.5 and 0.1% of previously sorbed Hg, indicating that Hg(II) is tightly bound by red mud once sorbed.
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Affiliation(s)
- David A Rubinos
- Department of Soil Science and Agricultural Chemistry. Faculty of Pharmacy, University of Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain.
| | - María Teresa Barral
- Department of Soil Science and Agricultural Chemistry. Faculty of Pharmacy, University of Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain
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Villadangos AF, Ordóñez E, Pedre B, Messens J, Gil JA, Mateos LM. Engineered coryneform bacteria as a bio-tool for arsenic remediation. Appl Microbiol Biotechnol 2014; 98:10143-52. [PMID: 25208910 DOI: 10.1007/s00253-014-6055-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/21/2014] [Accepted: 08/27/2014] [Indexed: 10/24/2022]
Abstract
Despite current remediation efforts, arsenic contamination in water sources is still a major health problem, highlighting the need for new approaches. In this work, strains of the nonpathogenic and highly arsenic-resistant bacterium Corynebacterium glutamicum were used as inexpensive tools to accumulate inorganic arsenic, either as arsenate (As(V)) or arsenite (As(III)) species. The assays made use of "resting cells" from these strains, which were assessed under well-established conditions and compared with C. glutamicum background controls. The two mutant As(V)-accumulating strains were those used in a previously published study: (i) ArsC1/C2, in which the gene/s encoding the mycothiol-dependent arsenate reductases is/are disrupted, and (ii) MshA/C mutants unable to produce mycothiol, the low molecular weight thiol essential for arsenate reduction. The As(III)-accumulating strains were either those lacking the arsenite permease activities (Acr3-1 and Acr3-2) needed in As(III) release or recombinant strains overexpressing the aquaglyceroporin genes (glpF) from Corynebacterium diphtheriae or Streptomyces coelicolor, to improve As(III) uptake. Both genetically modified strains accumulated 30-fold more As(V) and 15-fold more As(III) than the controls. The arsenic resistance of the modified strains was inversely proportional to their metal accumulation ability. Our results provide the basis for investigations into the use of these modified C. glutamicum strains as a new bio-tool in arsenic remediation efforts.
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Affiliation(s)
- Almudena F Villadangos
- Departament of Molecular Biology, Area of Microbiology, Faculty of Biology-Environmental Sciences, University of León, León, 24071, Spain
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Mallampati R, Valiyaveettil S. Apple peels--a versatile biomass for water purification? ACS APPLIED MATERIALS & INTERFACES 2013; 5:4443-4449. [PMID: 23635477 DOI: 10.1021/am400901e] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The presence of anions such as chromate, arsenate, and arsenite in drinking water is a major health concern in many parts of the world due to their high toxicity. Removal of such anions from water using low cost biomass is an efficient and affordable treatment process. Owing to the easy availability and biodegradability, we chose to use apple peel as a substrate for our investigations. Zirconium cations were immobilized onto the apple peel surface and used for the extraction of anions. Zirconium loaded apple peels were used to extract anions such as phosphate, arsenate, arsenite, and chromate ions from aqueous solutions. The presence of Zr cations on the apple peel surface was characterized using XPS. The modified adsorbent was characterized using SEM, EDS, and FT-IR. Zr treated apple peels showed efficient adsorption toward AsO2(-) (15.64 mg/g), AsO4(3-) (15.68 mg/g), Cr2O7(2-) (25.28 mg/g), and PO4(3-) (20.35 mg/g) anions. The adsorption and desorption studies revealed the adsorption mechanism involves electrostatic interactions. Anion removal efficiency was estimated by batch adsorption studies. Adsorption kinetic parameters for all anions at different concentrations were described using pseudo-first-order and pseudo-second-order rate equations. Langumir and Freundlich isotherms were used to validate our adsorption data. Arsenate and chromate anions were strongly adsorbed at the pH range from 2 to 6, while arsenite was extracted efficiently between pH 9 and 10. Overall, the Zr immobilized apple peel is an efficient adsorbent for common anionic pollutants.
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Villadangos AF, Van Belle K, Wahni K, Dufe VT, Freitas S, Nur H, De Galan S, Gil JA, Collet JF, Mateos LM, Messens J. Corynebacterium glutamicum survives arsenic stress with arsenate reductases coupled to two distinct redox mechanisms. Mol Microbiol 2011; 82:998-1014. [PMID: 22032722 DOI: 10.1111/j.1365-2958.2011.07882.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Arsenate reductases (ArsCs) evolved independently as a defence mechanism against toxic arsenate. In the genome of Corynebacterium glutamicum, there are two arsenic resistance operons (ars1 and ars2) and four potential genes coding for arsenate reductases (Cg_ArsC1, Cg_ArsC2, Cg_ArsC1' and Cg_ArsC4). Using knockout mutants, in vitro reconstitution of redox pathways, arsenic measurements and enzyme kinetics, we show that a single organism has two different classes of arsenate reductases. Cg_ArsC1 and Cg_ArsC2 are single-cysteine monomeric enzymes coupled to the mycothiol/mycoredoxin redox pathway using a mycothiol transferase mechanism. In contrast, Cg_ArsC1' is a three-cysteine containing homodimer that uses a reduction mechanism linked to the thioredoxin pathway with a k(cat)/K(M) value which is 10(3) times higher than the one of Cg_ArsC1 or Cg_ArsC2. Cg_ArsC1' is constitutively expressed at low levels using its own promoter site. It reduces arsenate to arsenite that can then induce the expression of Cg_ArsC1 and Cg_ArsC2. We also solved the X-ray structures of Cg_ArsC1' and Cg_ArsC2. Both enzymes have a typical low-molecular-weight protein tyrosine phosphatases-I fold with a conserved oxyanion binding site. Moreover, Cg_ArsC1' is unique in bearing an N-terminal three-helical bundle that interacts with the active site of the other chain in the dimeric interface.
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Valverde A, González-Tirante M, Medina-Sierra M, Santa-Regina I, García-Sánchez A, Igual JM. Diversity and community structure of culturable arsenic-resistant bacteria across a soil arsenic gradient at an abandoned tungsten-tin mining area. CHEMOSPHERE 2011; 85:129-134. [PMID: 21724233 DOI: 10.1016/j.chemosphere.2011.06.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/31/2011] [Accepted: 06/05/2011] [Indexed: 05/31/2023]
Abstract
We studied the bacterial diversity at a single location (the Terrubias mine; Salamanca province, Spain) with a gradient of soil As contamination to test if increasing levels of As would (1) change the preponderant groups of arsenic-resistant bacteria and (2) increase the tolerance thresholds to arsenite [As(III)] and arsenate [As(V)] of such bacteria. We studied the genetic and taxonomic diversity of culturable arsenic-resistant bacteria by PCR fingerprinting techniques and 16S rRNA gene sequencing. Then, the tolerance thresholds to As(III) and As(V) were determined for representative strains and mathematically analyzed to determine relationships between tolerances to As(III) and As(V), as well as these tolerances with the soil contamination level. The diversity of the bacterial community was, as expected, inversely related to the soil As content. The overall preponderant arsenic-resistant bacteria were Firmicutes (mainly Bacillus spp.) followed by γ-Proteobacteria (mainly Pseudomonas spp.), with increasing relative frequencies of the former as the soil arsenic concentration increased. Moreover, a strain of the species Rahnella aquatilis (γ-Proteobacteria class) exhibited strong endurance to arsenic, being described for the first time in literature such a phenotype within this bacterial species. Tolerances of the isolates to As(III) and As(V) were correlated but not with their origin (soil contamination level). Most of the strains (64%) showed relatively low tolerances to As(III) and As(V), but the second most numerous group of isolates (19%) showed increased tolerance to As(III) rather than to As(V), even though the As(V) anion is the prevalent arsenic species in soil solution at this location. To our knowledge, this is the first study to report a shift towards preponderance of Gram-positive bacteria (Firmicutes) related to high concentrations of soil arsenic. It was also shown that, under aerobic conditions, strains with relatively enhanced tolerance to As(III) predominated over the most As(V)-tolerant ones.
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Affiliation(s)
- Angel Valverde
- Instituto de Recursos Naturales y Agrobiología de Salamanca (CSIC), Apartado 257, 37071 Salamanca, Spain
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Yan L, Yin H, Zhang S, Leng F, Nan W, Li H. Biosorption of inorganic and organic arsenic from aqueous solution by Acidithiobacillus ferrooxidans BY-3. JOURNAL OF HAZARDOUS MATERIALS 2010; 178:209-217. [PMID: 20122794 DOI: 10.1016/j.jhazmat.2010.01.065] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 11/18/2009] [Accepted: 01/13/2010] [Indexed: 05/28/2023]
Abstract
The traditional techniques for removing low concentration arsenic are unsuitable. The biosorption characteristics of arsenite (iAs(III)) and monomethyl arsonate (MMA(V)) from aqueous solution by Acidithiobacillus ferrooxidans BY-3 (At. f BY-3) were investigated as a function of pH, contact time, initial arsenic concentration, biomass dosage and temperature in this study. Results indicated that Langmuir isotherm model fitted better than Freundlich model to the equilibrium data. Analysis of kinetic data showed that the biosorption processes of both iAs(III) and MMA(V) involved pseudo-second-order kinetics. The thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) of the biosorption process showed that the adsorption of iAs(III) and MMA(V) onto At. f BY-3 was feasible, spontaneous and endothermic under the examined conditions. The competitive biosorption of iAs(III) and MMA(V) in binary mixture system was evaluated, and the results indicated that At. f BY-3 favored MMA(V) biosorption. Fourier-transform infrared spectroscopy (FT-IR) showed -OH and -NH groups were involved in the biosorption process.
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Affiliation(s)
- Lei Yan
- MOE Key Laboratory of Arid and Grassland Ecology, School of Life Sciences, Lanzhou University, 222 South Tianshui Road, Lanzhou 730000, PR China
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Fu L, Wang J, Lu H, Su Y, Ren A. Comment on "the removal of phenolic compounds from aqueous solutions by organophilic bentonite". JOURNAL OF HAZARDOUS MATERIALS 2008; 151:851-854. [PMID: 18248887 DOI: 10.1016/j.jhazmat.2007.11.090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2007] [Revised: 10/18/2007] [Accepted: 11/26/2007] [Indexed: 05/25/2023]
Abstract
Quotation and calculation accuracy can play a key role in a scientific paper. This comment mainly presents the possible errors in an article by Akçay et al., including the questionable expression of Polanyi potential (epsilon) in the Dubinin-Radushkevich (DR) equation used by the authors and the discrepancies in adsorption thermodynamic parameters study.
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Affiliation(s)
- Lin Fu
- College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
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