Use of Silicate Minerals for pH Control during Reductive Dechlorination of Chloroethenes in Batch Cultures of Different Microbial Consortia

Lacroix, Elsa; Brovelli, Alessandro; Barry, David Andrew; Holliger, Christof

doi:10.1128/aem.00493-14

Cited by 34 publications

(28 citation statements)

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“…Moreover, silicates are likely interacting with the pH probe glass membrane. Such a difficulty can be circumvented by assessing acidity function measurements and using spectrocolorimetry [46,47].…”

Section: Protonation Of the Silicate Chainsmentioning

confidence: 99%

Time resolved alkali silicate decondensation by sodium hydroxide solution

et al. 2020

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Silica is by far the chemical compound the most widespread and used around the world: as a raw product in the buildings and roads industry, as concrete, or as a processed product in the manufacture of glass, ceramics or zeolites. In alkali silicate solutions-often used to synthesize those materials-a complex interplay of decondensation and condensation processes leads to the restructuring of silicate clusters at the atomic scale on a short time-scale. We were able to deconvolute these effects by combining time resolved small angle x-ray scattering, nuclear magnetic resonance, and parallel tempering simulations. We investigated the impact of a dilution by pure water or by a sodium hydroxide solution on the speciation and size of the dissolved silicates in solution. Herein, we show that the silicate clusters are not affected by dilution, suggesting that sodium cations protect the silicate clusters from hydrolysis. Decondensation is triggered by hydroxide ions that weaken and break Si-O bonds. Alongside the decondensation, the evolution of the computed protonation state of the silica species indicates a change in the interaction potential. Our results pave the way towards the investigation at the atomic scale of more complex systems implying alkali silicate solutions in condensation process by the addition of calcium or aluminum to synthesize aluminosilicate binders, hydrogels or zeolites.

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Section: Protonation Of the Silicate Chainsmentioning

confidence: 99%

Time resolved alkali silicate decondensation by sodium hydroxide solution

et al. 2020

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“…The detection of large amounts of methane at these locations, combined with the proven presence of the full OHR potential, indicated that the partial degradation of PCE was not a consequence of a lack of available electron donor (Table S5). A closer look at other variables showed that pH-values at wells NA-1 and NA-6 dropped to low values around 5.0-5.5, which are known to severely impede cisDCE and VC dechlorination (Lacroix et al, 2014). Overall, the pH was in general below 7.0 at all wells, probably a consequence of the mineralogical composition of the bedrock at this site, which is formed by minerals such as biotite, an iron-and manganese silicate, providing a weak pH-buffering capacity.…”

Section: Site B-monitoring Of Reductive Dechlorination During An Erdmentioning

confidence: 99%

Validation of an Integrative Methodology to Assess and Monitor Reductive Dechlorination of Chlorinated Ethenes in Contaminated Aquifers

Tarnawski

Rossi

Brennerova

et al. 2016

Front. Environ. Sci.

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Bioremediation of tetra-and trichloroethene-contaminated aquifers is frequently hampered due to incomplete dechlorination to the more toxic dichloroethene (DCE) and vinyl chloride (VC), indicating insufficient knowledge about the biological mechanisms related to aquifer functioning. A methodology based on the joint analysis of geochemical and microbiological datasets was developed to assess the presence of the biochemical potential for complete reductive dechlorination to harmless ethene and to explain the reasons for which degradation often stalls at the more toxic intermediates. This methodology is composed of three successive steps, with (i) the acquisition of geochemical data including chlorinated ethenes (CEs), (ii) the detailed analysis of the bacterial community structures (BCS) as well as the biochemical potential for complete dechlorination using microcosms and molecular detection of organohalide-respiring bacteria and key reductive dehalogenases, and (iii) a statistical Multiple Factor Analysis (MFA) combining the above mentioned abiotic and biotic variables in a functional modeling of the contaminated aquifer. The methodology was validated by analyzing two chlorinated ethenes-contaminated sites. Results from the first site showed that the full biochemical potential for ethene production was present in situ. However, redox potential was overall too high and locally manganese reduction out-competed CEs reduction, explaining the reasons for the local accumulation of DCE and VC to a lesser extent. The second contaminated aquifer was under bioremediation by successive cheese whey injections. Analysis demonstrated that cheese whey additions led to increasingly reduced redox conditions and that hampered reductive dechlorination was not due to competition with other anaerobic respiration processes. Complete reductive dechlorination to ethene was preferentially occurring under methanogenic conditions. DCE and VC accumulation was probably induced first by low pH resulting from whey fermentation and at a later stage by phosphate limitation. In conclusions, Tarnawski et al.Assessment Methodology for Chloroethenes Bioremediation the proposed methodology successfully allowed the identification of biogeochemical processes limiting or supporting complete dechlorination in both aquifers. The integrative approach provided fundamental information about the functional heterogeneity of the contaminated aquifers in time and space, and can be used as a reliable tool to support corrective decision-making in the development of remediation strategies based on natural attenuation of CEs.

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“…The results showed that pH in the cultures supplemented with 5 to 20 mM glucose decreased from 5.1 to 5.9 after 20 days, while the pH was maintained between 6.6 and 6.9 with the addition of 0.5 or 2.5 mM of glucose. Inhibitory effect of acidic conditions on reductive dehalogenation has been previously reported (Lacroix et al, 2014), while glucose itself had no effect on the debromination (SM Fig. S3).…”

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confidence: 83%