Biostimulation for Anaerobic Bioremediation of Chlorinated Solvents

Henry, Bruce M.

doi:10.1007/978-1-4419-1401-9_12

Cited by 16 publications

(15 citation statements)

References 63 publications

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“…A wide range of fermentable carbon substrates have been used as electron donors and introduced into groundwater to stimulate the growth of indigenous bacteria (biostimulation), including soluble and solid phase organic materials, and emulsified solutions of vegetable oils (Henry 2010). Before attempting to stimulate indigenous bacteria, it is necessary to demonstrate that the chlororespiring bacteria are capable of reducing CE to ETH by either analyzing the microbial population or by identifying the presence of intermediate and final degradation products in the groundwater.…”

Section: Introductionmentioning

confidence: 99%

“…Although biostimulation and bioaugmentation have been investigated and adapted as a groundwater remediation technologies, successful remediation of groundwater contaminated with CE continues to be a problem (Bradley and Chapelle 1996;Stroo et al 2012), especially in geologic settings such as fractured rock aquifers where remediation amendments move preferentially through permeable fractures and bypass contaminated groundwater in low-permeability aquifer materials (Sale et al 2008;Henry 2010). Aqueous phase CE can diffuse from fractures into the intrinsic porosity of the rock (rock matrix) and act as a long-term, spatially pervasive source of contamination as they diffuse back into permeable fractures in response to decreasing concentrations in fractures (Parker et al 1994;Parker et al 1997).…”

Section: Introductionmentioning

confidence: 99%

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Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix

Shapiro¹,

Tiedeman

Imbrigiotta

et al. 2017

Groundwater

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A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site characterization identified groundwater fluxes to formulate the CE mass balance in the rock volume exposed to the injected remediation amendments. Differences in the CE fluxes into and out of the rock volume identify the total CE mobilized from diffusion, desorption, and nonaqueous phase liquid dissolution under pre- and postinjection conditions. The initial CE mass in the rock matrix prior to remediation is estimated using analyses of CE in rock core. The CE mass mobilized per year under preinjection conditions is small relative to the total CE mass in the rock, indicating that current pump-and-treat and natural attenuation conditions are likely to require hundreds of years to achieve groundwater concentrations that meet regulatory guidelines. The postinjection CE mobilization rate increased by approximately an order of magnitude over the 5 years of monitoring after the amendment injection. This rate is likely to decrease and additional remediation applications over several decades would still be needed to reduce CE mass in the rock matrix to levels where groundwater concentrations in fractures achieve regulatory standards.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix

Shapiro¹,

Tiedeman

Imbrigiotta

et al. 2017

Groundwater

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“…The identification of the mechanisms involved in anaerobic reductive dechlorination also opened the way for the application of the technology of enhanced, as opposed to intrinsic, anaerobic remediation of chloroethenes, by adding an electron donor to stimulate microbial activity (Morse et al 1998). Many organic substances and compounds can act as electron donors (Henry 2010), provided that they supply H 2 when they break down, as H 2 has been established as the predominant electron donor for dechlorination (Bradley 2003). Other microorganisms will compete for H 2 though, including sulfate-reducing bacteria (SRB).…”

Section: Introduction and Scope Of Researchmentioning

confidence: 99%

Chloroethene Biotransformation in the Presence of Different Sulfate Concentrations

Pantazidou¹,

Panagiotakis²,

Mamais³

et al. 2011

Groundwater Monitoring Rem

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This paper aims to reconcile discrepancies among reports of dechlorination performance in the presence of sulfate, by analyzing data from the literature, presenting results from laboratory experiments performed with mixed anaerobic microbial cultures, and synthesizing respective findings. A complete set of metrics for dechlorination progress was developed and used in the analysis of selected field and laboratory studies. When differences in site and experimental conditions are accounted for and definitions of dechlorination completeness are harmonized, the inverse relationship between dechlorination performance and sulfate concentration becomes clearer. This relationship was investigated in detail with laboratory experiments on mixed anaerobic microbial cultures enriched with the same concentration of trichloroethylene (TCE) and different sulfate concentrations, equal to near zero (considered as the baseline culture), 30, 400, and 1100 mg/L. In all experiments, sulfate reduction proceeded concurrently with dechlorination. The observed behavior was bimodal, indicating a transition in dechlorination performance between 30 and 400 mg/L. Under low donor to acceptor stoichiometry conditions, TCE dechlorination was incomplete in all experiments after 14 days, while the percentage of TCE moles reduced to vinyl chloride was lower by about 50% in the experiments with high sulfate concentrations. When donor was added in excess to stoichiometry needs for TCE reduction, TCE dechlorination was complete in the baseline culture, while only little ethene was detected in the high sulfate concentration cultures. When all studies are considered together, it appears that the presence of sulfate does not preclude complete dechlorination but rather delays it. Data analysis also suggests that the proposed upper limit of 500 mg/L for the range of initial sulfate concentration that is not problematic for dechlorination should be revised to a lower value.

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“…In more permeable unconsolidated porous media, approaches to distributing remediation amendments can involve recirculating water withdrawn at extraction wells and reinjecting the water into the subsurface to avoid sending amendments to waste (Henry 2010). That approach might be viable in source zones within the highly weathered rocks at NAWC, with more spatially continuous high permeability.…”

Section: Amendment Injection Strategymentioning

confidence: 99%

Bioremediation in Fractured Rock: 1. Modeling to Inform Design, Monitoring, and Expectations

Tiedeman¹,

Shapiro

Hsieh

et al. 2017

Groundwater

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Field characterization of a trichloroethene (TCE) source area in fractured mudstones produced a detailed understanding of the geology, contaminant distribution in fractures and the rock matrix, and hydraulic and transport properties. Groundwater flow and chemical transport modeling that synthesized the field characterization information proved critical for designing bioremediation of the source area. The planned bioremediation involved injecting emulsified vegetable oil and bacteria to enhance the naturally occurring biodegradation of TCE. The flow and transport modeling showed that injection will spread amendments widely over a zone of lower-permeability fractures, with long residence times expected because of small velocities after injection and sorption of emulsified vegetable oil onto solids. Amendments transported out of this zone will be diluted by groundwater flux from other areas, limiting bioremediation effectiveness downgradient. At nearby pumping wells, further dilution is expected to make bioremediation effects undetectable in the pumped water. The results emphasize that in fracture-dominated flow regimes, the extent of injected amendments cannot be conceptualized using simple homogeneous models of groundwater flow commonly adopted to design injections in unconsolidated porous media (e.g., radial diverging or dipole flow regimes). Instead, it is important to synthesize site characterization information using a groundwater flow model that includes discrete features representing high- and low-permeability fractures. This type of model accounts for the highly heterogeneous hydraulic conductivity and groundwater fluxes in fractured-rock aquifers, and facilitates designing injection strategies that target specific volumes of the aquifer and maximize the distribution of amendments over these volumes.

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Biostimulation for Anaerobic Bioremediation of Chlorinated Solvents

Cited by 16 publications

References 63 publications

Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix

Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix

Chloroethene Biotransformation in the Presence of Different Sulfate Concentrations

Bioremediation in Fractured Rock: 1. Modeling to Inform Design, Monitoring, and Expectations

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