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Botti A, Musmeci E, Matturro B, Vanzetto G, Bosticco C, Negroni A, Rossetti S, Fava F, Biagi E, Zanaroli G. Chemical-physical parameters and microbial community changes induced by electrodes polarization inhibit PCB dechlorination in a marine sediment. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133878. [PMID: 38447365 DOI: 10.1016/j.jhazmat.2024.133878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/30/2024] [Accepted: 02/22/2024] [Indexed: 03/08/2024]
Abstract
Microbial reductive dechlorination of organohalogenated pollutants is often limited by the scarcity of electron donors, that can be overcome with microbial electrochemical technologies (METs). In this study, polarized electrodes buried in marine sediment microcosms were investigated to stimulate PCB reductive dechlorination under potentiostatic (-0.7 V vs Ag/AgCl) and galvanostatic conditions (0.025 mA·cm-2-0.05 mA·cm-2), using graphite rod as cathode and iron plate as sacrificial anode. A single circuit and a novel two antiparallel circuits configuration (2AP) were investigated. Single circuit polarization impacted the sediment pH and redox potential (ORP) proportionally to the intensity of the electrical input and inhibited PCB reductive dechlorination. The effects on the sediment's pH and ORP, along with the inhibition of PCB reductive dechlorination, were mitigated in the 2AP system. Electrodes polarization stimulated sulfate-reduction and promoted the enrichment of bacterial clades potentially involved in sulfate-reduction as well as in sulfur oxidation. This suggested the electrons provided were consumed by competitors of organohalide respiring bacteria and specifically sequestered by sulfur cycling, which may represent the main factor limiting the applicability of METs for stimulating PCB reductive dechlorination in marine sediments.
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Affiliation(s)
- Alberto Botti
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Eliana Musmeci
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Bruna Matturro
- Water Research Institute (IRSA), National Research Council (CNR), 00010 Montelibretti, Italy; National Biodiversity Future Center, 90133 Palermo, Italy
| | - Giampietro Vanzetto
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Caterina Bosticco
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Andrea Negroni
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Simona Rossetti
- Water Research Institute (IRSA), National Research Council (CNR), 00010 Montelibretti, Italy
| | - Fabio Fava
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Elena Biagi
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Giulio Zanaroli
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
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Meng L, Tomita R, Yoshida T, Yoshida N. Soil organic matter and nutrient availability affect the applicability of low-carbon energy source in Dehalococcoides-augmented soil. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132251. [PMID: 37591166 DOI: 10.1016/j.jhazmat.2023.132251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 08/02/2023] [Accepted: 08/06/2023] [Indexed: 08/19/2023]
Abstract
Dehalococcoides is a functional microorganism that completely dechlorinates trichloroethene (TCE). Augmentation with pure Dehalococcoides is important for reducing environmental disturbances that accompany bioaugmentation. However, the applicability of Dehalococcoides-bioaugmentation to contaminated soils is unclear. In this study, seven low-carbon energy sources (methanol, formate, acetate, ethanol, lactate, citrate, and benzoate) were used as electron donors for Dehalococcides to evaluate its applicability in remediating TCE-contaminated soils. Soil microcosms supplemented with ethanol, formate, or lactate showed relatively high dechlorination activity within 111-180 days. The functional gene profiles predicted by PICRUSt2 from 16 S rRNA gene sequences were similar in the proportions of dehydrogenases, which initiate electron donor oxidation, in all soils and did not seem to reflect Dehalococcoides-bioaugmentation applicability. Soils with higher organic matter content (>3.2%; dry weight base) and protein concentration (>1.6 µg/mL) supported complete dechlorination. These results suggest that organic matter and nutrient availability mainly affect successful TCE dechlorination in Dehalococcoides-augmented soils. The study offers significant experimental support for comprehending the suitability of low-carbon energy sources in successful bioaugmentation, aiming to mitigate environmental disturbances associated with the process.
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Affiliation(s)
- Lingyu Meng
- Department of Civil Engineering, Nagoya Institute of Technology (Nitech), Nagoya 466-8555, Japan.
| | - Ryuya Tomita
- Department of Civil Engineering, Nagoya Institute of Technology (Nitech), Nagoya 466-8555, Japan.
| | - Tomoki Yoshida
- Department of Civil Engineering, Nagoya Institute of Technology (Nitech), Nagoya 466-8555, Japan.
| | - Naoko Yoshida
- Department of Civil Engineering, Nagoya Institute of Technology (Nitech), Nagoya 466-8555, Japan.
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3
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Yang Y, Cápiro NL, Yan J, Marcet TF, Pennell KD, Löffler FE. Resilience and recovery of Dehalococcoides mccartyi following low pH exposure. FEMS Microbiol Ecol 2017; 93:4411799. [DOI: 10.1093/femsec/fix130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/05/2017] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yi Yang
- Department of Civil and Environmental Engineering, University of Tennessee, 325 John D. Tickle Bldg, 851 Neyland Drive, Knoxville, TN 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Natalie L. Cápiro
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Jun Yan
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Department of Microbiology, University of Tennessee, M409 Walters Life Science Bldg, Knoxville, TN 37996, USA
| | - Tyler F. Marcet
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Kurt D. Pennell
- Department of Civil and Environmental Engineering, 200 College Avenue, Tufts University, Medford, MA 02155, USA
| | - Frank E. Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, 325 John D. Tickle Bldg, 851 Neyland Drive, Knoxville, TN 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, 1416 Circle Drive, Knoxville, TN 37996, USA
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Bldg 1520, Bethel Valley Road, Oak Ridge, TN 37831, USA
- Department of Microbiology, University of Tennessee, M409 Walters Life Science Bldg, Knoxville, TN 37996, USA
- Department of Biosystems Engineering and Soil Science, University of Tennessee, 2506 E.J. Chapman Dr., Knoxville, TN 37996, USA
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4
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Yang Y, Cápiro NL, Marcet TF, Yan J, Pennell KD, Löffler FE. Organohalide Respiration with Chlorinated Ethenes under Low pH Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:8579-8588. [PMID: 28665587 DOI: 10.1021/acs.est.7b01510] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bioremediation at chlorinated solvent sites often leads to groundwater acidification due to electron donor fermentation and enhanced dechlorination activity. The microbial reductive dechlorination process is robust at circumneutral pH, but activity declines at groundwater pH values below 6.0. Consistent with this observation, the activity of tetrachloroethene (PCE) dechlorinating cultures declined at pH 6.0 and was not sustained in pH 5.5 medium, with one notable exception. Sulfurospirillum multivorans dechlorinated PCE to cis-1,2-dichloroethene (cDCE) in pH 5.5 medium and maintained this activity upon repeated transfers. Microcosms established with soil and aquifer materials from five distinct locations dechlorinated PCE-to-ethene at pH 5.5 and pH 7.2. Dechlorination to ethene was maintained following repeated transfers at pH 7.2, but no ethene was produced at pH 5.5, and only the transfer cultures derived from the Axton Cross Superfund (ACS) microcosms sustained PCE dechlorination to cDCE as a final product. 16S rRNA gene amplicon sequencing of pH 7.2 and pH 5.5 ACS enrichments revealed distinct microbial communities, with the dominant dechlorinator being Dehalococcoides in pH 7.2 and Sulfurospirillum in pH 5.5 cultures. PCE-to-trichloroethene- (TCE-) and PCE-to-cDCE-dechlorinating isolates obtained from the ACS pH 5.5 enrichment shared 98.6%, and 98.5% 16S rRNA gene sequence similarities to Sulfurospirillum multivorans. These findings imply that sustained Dehalococcoides activity cannot be expected in low pH (i.e., ≤ 5.5) groundwater, and organohalide-respiring Sulfurospirillum spp. are key contributors to in situ PCE reductive dechlorination under low pH conditions.
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Affiliation(s)
| | - Natalie L Cápiro
- Department of Civil and Environmental Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Tyler F Marcet
- Department of Civil and Environmental Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | | | - Kurt D Pennell
- Department of Civil and Environmental Engineering, Tufts University , Medford, Massachusetts 02155, United States
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Wang SY, Chen SC, Lin YC, Kuo YC, Chen JY, Kao CM. Acidification and sulfide formation control during reductive dechlorination of 1,2-dichloroethane in groundwater: Effectiveness and mechanistic study. CHEMOSPHERE 2016; 160:216-229. [PMID: 27376861 DOI: 10.1016/j.chemosphere.2016.06.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/21/2016] [Accepted: 06/17/2016] [Indexed: 06/06/2023]
Abstract
To enhance the reductive dechlorination of 1,2-dichloroethane (DCA) in groundwater, substrate injection may be required. However, substrate biodegradation causes groundwater acidification and sulfide production, which inhibits the bacteria responsible for DCA dechlorination and results in an odor problem. In the microcosm study, the effectiveness of the addition of ferrous sulfate (FS), desulfurization slag (DS), and nanoscale zero-valent iron (nZVI) on acidification and sulfide control was studied during reductive dechlorination of DCA, and the emulsified substrate (ES) was used as the substrate. Up to 94% of the sulfide was removed with FS and DS addition (0.25 wt%) (initial DCA concentration = 13.5 mg/L). FS and DS amendments resulted in the formation of a metal sulfide, which reduced the hydrogen sulfide concentration as well as the subsequent odor problem. Approximately 96% of the DCA was degraded under reductive dechlorination with nZVI or DS addition using ES as the substrate. In microcosms with nZVI or DS addition, the sulfide concentration was reduced to less than 15 μg/L. Acidification can be controlled via hydroxide ions production after nZVI oxidation and reaction of free CaO (released from DS) with water, which enhanced DCA dechlorination. The quantitative polymerase chain reaction results confirmed that the microcosms with nZVI added had the highest Dehalococcoides population (up to 2.5 × 10(8) gene copies/g soil) due to effective acidification control. The α-elimination mechanism was the main abiotic process, and reductive dechlorination dominated by Dehalococcides was the biotic mechanism that resulted in DCA removal. More than 22 bacterial species were detected, and dechlorinating bacteria existed in soils under alkaline and acidic conditions.
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Affiliation(s)
- S Y Wang
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan
| | - S C Chen
- Department of Life Sciences, National Central University, Chung-Li, Taiwan
| | - Y C Lin
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan
| | - Y C Kuo
- Formosa Petrochemical Co., Kaohsiung, Taiwan
| | - J Y Chen
- Formosa Petrochemical Co., Kaohsiung, Taiwan
| | - C M Kao
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan
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6
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Microorganisms meet solid minerals: interactions and biotechnological applications. Appl Microbiol Biotechnol 2016; 100:6935-46. [DOI: 10.1007/s00253-016-7678-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/08/2016] [Accepted: 06/11/2016] [Indexed: 10/21/2022]
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Paul L, Smolders E. Bioenhanced dissolution of dense non-aqueous phase of trichloroethylene as affected by iron reducing conditions: model systems and environmental samples. CHEMOSPHERE 2015; 119:1113-1119. [PMID: 25460750 DOI: 10.1016/j.chemosphere.2014.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 08/28/2014] [Accepted: 09/05/2014] [Indexed: 06/04/2023]
Abstract
The anaerobic biotransformation of trichloroethylene (TCE) can be affected by competing electron acceptors such as Fe (III). This study assessed the role of Fe (III) reduction on the bioenhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). Columns were set up as 1-D diffusion cells consisting of a lower DNAPL layer, a layer with an aquifer substratum and an upper water layer that is regularly refreshed. The substrata used were either inert sand or sand coated with 2-line ferrihydrite (HFO) or two environmental Fe (III) containing samples. The columns were inoculated with KB-1 and were repeatedly fed with formate. In none of the diffusion cells, vinyl chloride or ethene was detected while dissolved and extractable Fe (II) increased strongly during 60 d of incubation. The cis-DCE concentration peaked at 4.0 cm from the DNAPL (inert sand) while it was at 3.4 cm (sand+HFO), 1.7 cm and 2.5 cm (environmental samples). The TCE concentration gradients near the DNAPL indicate that the DNAPL dissolution rate was larger than that in an abiotic cell by factors 1.3 (inert sand), 1.0 (sand+HFO) and 2.2 (both environmental samples). This results show that high bioavailable Fe (III) in HFO reduces the TCE degradation by competitive Fe (III) reduction, yielding lower bioenhanced dissolution. However, Fe (III) reduction in environmental samples was not reducing TCE degradation and the dissolution factor was even larger than that of inert sand. It is speculated that physical factors, e.g. micro-niches in the environmental samples protect microorganisms from toxic concentrations of TCE.
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Affiliation(s)
- Laiby Paul
- Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium
| | - Erik Smolders
- Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
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8
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Philips J, Miroshnikov A, Haest PJ, Springael D, Smolders E. Motile Geobacter dechlorinators migrate into a model source zone of trichloroethene dense non-aqueous phase liquid: experimental evaluation and modeling. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 170:28-38. [PMID: 25306502 DOI: 10.1016/j.jconhyd.2014.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 09/17/2014] [Accepted: 09/24/2014] [Indexed: 06/04/2023]
Abstract
Microbial migration towards a trichloroethene (TCE) dense non-aqueous phase liquid (DNAPL) could facilitate the bioaugmentation of TCE DNAPL source zones. This study characterized the motility of the Geobacter dechlorinators in a TCE to cis-dichloroethene dechlorinating KB-1(™) subculture. No chemotaxis towards or away from TCE was found using an agarose in-plug bridge method. A second experiment placed an inoculated aqueous layer on top of a sterile sand layer and showed that Geobacter migrated several centimeters in the sand layer in just 7days. A random motility coefficient for Geobacter in water of 0.24±0.02cm(2)·day(-1) was fitted. A third experiment used a diffusion-cell setup with a 5.5cm central sand layer separating a DNAPL from an aqueous top layer as a model source zone to examine the effect of random motility on TCE DNAPL dissolution. With top layer inoculation, Geobacter quickly colonized the sand layer, thereby enhancing the initial TCE DNAPL dissolution flux. After 19days, the DNAPL dissolution enhancement was only 24% lower than with an homogenous inoculation of the sand layer. A diffusion-motility model was developed to describe dechlorination and migration in the diffusion-cells. This model suggested that the fast colonization of the sand layer by Geobacter was due to the combination of random motility and growth on TCE.
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Affiliation(s)
- Jo Philips
- Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven (University of Leuven), Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
| | - Alexey Miroshnikov
- Department of Mathematics and Statistics, University of Massachusetts, Lederle Graduate Research Tower, Amherst MA 01003-9305, USA.
| | - Pieter Jan Haest
- Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven (University of Leuven), Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
| | - Dirk Springael
- Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven (University of Leuven), Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
| | - Erik Smolders
- Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven (University of Leuven), Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
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9
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Paul L, Smolders E. Inhibition of iron (III) minerals and acidification on the reductive dechlorination of trichloroethylene. CHEMOSPHERE 2014; 111:471-7. [PMID: 24997954 DOI: 10.1016/j.chemosphere.2014.04.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 04/04/2014] [Accepted: 04/18/2014] [Indexed: 05/25/2023]
Abstract
Reductive dechlorination of chlorinated ethenes is inhibited by acidification and by the presence of Fe (III) as a competitive electron acceptor. Synergism between both factors on dechlorination is predicted as reductive dissolution of Fe (III) minerals is facilitated by acidification. This study was set-up to assess this synergism for two common aquifer Fe (III) minerals, goethite and ferrihydrite. Anaerobic microbial dechlorination of trichloroethylene (TCE) by KB-1 culture and formate as electron donor was investigated in anaerobic batch containers at different solution pH values (6.2-7.2) in sand coated with these Fe minerals and a sand only as control. In the absence of Fe, lowering substrate pH from 7.2 to 6.2 increased the time for 90% TCE degradation from 14±1d to 42±4d. At pH 7.2, goethite did not affect TCE degradation time while ferrihydrite increased the degradation time to 19±1d compared to the no Fe control. At pH 6.2, 90% degradation was at 78±1 (ferrihydrite) or 131±1d (goethite). Ferrous iron production in ferrihydrite treatment increased between pH 7.2 and 6.5 but decreased by further lowering pH to 6.2, likely due to reduced microbial activity. This study confirms that TCE is increasingly inhibited by the combined effect of acidification and bioavailable Fe (III), however no evidence was found for synergistic inhibition since Fe reduction did not increase as pH decreases. To the best of our knowledge, this is the first study where effect of pH and Fe (III) reduction on TCE was simultaneously tested. Acid Fe-rich aquifers need sufficient buffering and alkalinity to ensure swift degradation of chlorinated ethenes.
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Affiliation(s)
- Laiby Paul
- Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
| | - Erik Smolders
- Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
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Lacroix E, Brovelli A, Maillard J, Rohrbach-Brandt E, Barry DA, Holliger C. Use of silicate minerals for long-term pH control during reductive dechlorination of high tetrachloroethene concentrations in continuous flow-through columns. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 482-483:23-35. [PMID: 24636885 DOI: 10.1016/j.scitotenv.2014.02.099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 02/12/2014] [Accepted: 02/21/2014] [Indexed: 06/03/2023]
Abstract
The long-term buffering potential of three silicate minerals (diopside, fayalite and forsterite) present as fine particles in porous quartz sand medium was evaluated in flow-through column experiments over a period of 6.5 months. The columns were operated with PCE concentrations close to saturation and inoculated with the organohalide-respiring consortium SDC-9™, which is able to completely dechlorinate PCE to ethene at high concentrations. In the absence of pH buffering agents, fermentation and organohalide respiration drove the pH close to 6.1, leading to severe inhibition of PCE dechlorination. Forsterite and fayalite were able to maintain the pH close to 7.5 and 6.5, respectively, and to sustain the production of VC and ethene. Diopside gradually lost its buffering capacity during the first 84 days due to the formation of a low reactive leached layer but dechlorination to cis-DCE was still achieved. Among the three minerals tested, forsterite was identified as the best buffering agent. Its presence led to the best PCE removal performance and the highest relative abundance of Dehalococcoides. This study showed that forsterite and fayalite are promising sources of long-term pH buffering for in situ bioremediation of source-zone PCE.
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Affiliation(s)
- Elsa Lacroix
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland; Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland
| | - Alessandro Brovelli
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland
| | - Julien Maillard
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland
| | - Emmanuelle Rohrbach-Brandt
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland
| | - D A Barry
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland
| | - Christof Holliger
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland.
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11
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Use of silicate minerals for pH control during reductive dechlorination of chloroethenes in batch cultures of different microbial consortia. Appl Environ Microbiol 2014; 80:3858-67. [PMID: 24747895 DOI: 10.1128/aem.00493-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In chloroethene-contaminated sites undergoing in situ bioremediation, groundwater acidification is a frequent problem in the source zone, and buffering strategies have to be implemented to maintain the pH in the neutral range. An alternative to conventional soluble buffers is silicate mineral particles as a long-term source of alkalinity. In previous studies, the buffering potentials of these minerals have been evaluated based on abiotic dissolution tests and geochemical modeling. In the present study, the buffering potentials of four silicate minerals (andradite, diopside, fayalite, and forsterite) were tested in batch cultures amended with tetrachloroethene (PCE) and inoculated with different organohalide-respiring consortia. Another objective of this study was to determine the influence of pH on the different steps of PCE dechlorination. The consortia showed significant differences in sensitivities toward acidic pH for the different dechlorination steps. Molecular analysis indicated that Dehalococcoides spp. that were present in all consortia were the most pH-sensitive organohalide-respiring guild members compared to Sulfurospirillum spp. and Dehalobacter spp. In batch cultures with silicate mineral particles as pH-buffering agents, all four minerals tested were able to maintain the pH in the appropriate range for reductive dechlorination of chloroethenes. However, complete dechlorination to ethene was observed only with forsterite, diopside, and fayalite. Dissolution of andradite increased the redox potential and did not allow dechlorination. With forsterite, diopside, and fayalite, dechlorination to ethene was observed but at much lower rates for the last two dechlorination steps than with the positive control. This indicated an inhibition effect of silicate minerals and/or their dissolution products on reductive dechlorination of cis-dichloroethene and vinyl chloride. Hence, despite the proven pH-buffering potential of silicate minerals, compatibility with the bacterial community involved in in situ bioremediation has to be carefully evaluated prior to their use for pH control at a specific site.
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12
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Hiortdahl KM, Borden RC. Enhanced reductive dechlorination of tetrachloroethene dense nonaqueous phase liquid with EVO and Mg(OH)2. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 48:624-631. [PMID: 24328264 DOI: 10.1021/es4042379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In situ treatment of dense nonaqueous phase liquids (DNAPL) by enhanced reductive dechlorination (ERD) can be limited by contaminant toxicity, low pH, and challenges in effectively delivering electron donor. Flushing emulsified vegetable oil (EVO), colloidal Mg(OH)2 buffer, and a bioaugmentation culture (BC) through a zone containing neat tetrachloroethene (PCE) was effective in reducing contaminant toxicity, limiting pH declines, and accelerating bioenhanced dissolution of the DNAPL. In the effluent of porous media columns with little fine material, PCE concentrations reached a maximum of 40-50 times PCE aqueous solubility in water, demonstrating NAPL PCE was distributed throughout the 1.5 m column length. In a column treated with only EVO+BC, reductive dechlorination was limited. However, a single injection of EVO+Mg(OH)2+BC was effective in reducing PCE to below detection for over 400 days with a large increase in Cl(-) and dichloroethene (DCE), accelerating bioenhanced DNAPL dissolution. Dechlorination rates gradually increased over time with the rate of total ethene (TE) release from the Mg(OH)2+EVO+BC column reaching 5-6 times the TE release rate from the EVO+BC column. The accelerated dechlorination was likely due to both Mg(OH)2 addition which limited pH declines from HCl, volatile fatty acids (VFAs), and inorganic carbon (IC) production, and formation of a mixed PCE-vegetable oil NAPL which provided a readily accessible electron donor, resulting in rapid PCE degradation with reduced PCE toxicity.
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Affiliation(s)
- Kirsten M Hiortdahl
- Department of Civil, Construction and Environmental Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
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