Protocol for Enhanced in situ Bioremediation Using Emulsified Edible Oil

Borden, Robert C.

doi:10.21236/ada451205

Cited by 9 publications

(9 citation statements)

References 44 publications

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“…mccartyi bioaugmentation cultures. While direct addition of butyrate in situ has rarely been reported, butyrate is a major fermentation product when glucose/molasses and emulsified vegetable oil are amended as groundwater biostimulation reagents. ,− Overall, microcosms stimulated by chain elongation initially propelled TCE to ethene reduction using H 2 produced during elongation of acetate and ethanol. Chain elongation also banked electrons into butanol and butyrate, which subsequently served as H 2 sources maintaining the reductive dechlorination activity.…”

Section: Resultsmentioning

confidence: 99%

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Robles

Yellowman

Joshi

et al. 2021

Environ. Sci. Technol.

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In situ anaerobic groundwater bioremediation of trichloroethene (TCE) to nontoxic ethene is contingent on organohalide-respiring Dehalococcoidia, the most common strictly hydrogenotrophic Dehalococcoides mccartyi (D. mccartyi). The H2 requirement for D. mccartyi is fulfilled by adding various organic substrates (e.g., lactate, emulsified vegetable oil, and glucose/molasses), which require fermenting microorganisms to convert them to H2. The net flux of H2 is a crucial controlling parameter in the efficacy of bioremediation. H2 consumption by competing microorganisms (e.g., methanogens and homoacetogens) can diminish the rates of reductive dechlorination or stall the process altogether. Furthermore, some fermentation pathways do not produce H2 or having H2 as a product is not always thermodynamically favorable under environmental conditions. Here, we report on a novel application of microbial chain elongation as a H2-producing process for reductive dechlorination. In soil microcosms bioaugmented with dechlorinating and chain-elongating enrichment cultures, near stoichiometric conversion of TCE (0.07 ± 0.01, 0.60 ± 0.03, and 1.50 ± 0.20 mmol L–1 added sequentially) to ethene was achieved when initially stimulated by chain elongation of acetate and ethanol. Chain elongation initiated reductive dechlorination by liberating H2 in the conversion of acetate and ethanol to butyrate and caproate. Syntrophic fermentation of butyrate, a chain-elongation product, to H2 and acetate further sustained the reductive dechlorination activity. Methanogenesis was limited during TCE dechlorination in soil microcosms and absent in transfer cultures fed with chain-elongation substrates. This study provides critical fundamental knowledge toward the feasibility of chlorinated solvent bioremediation based on microbial chain elongation.

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Section: Resultsmentioning

confidence: 99%

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Robles

Yellowman

Joshi

et al. 2021

Environ. Sci. Technol.

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“…Acetate and vegetable oil were used to successfully stimulate RDX degradation under anaerobic conditions in different studies (Borden et al., ; Livermore et al., ). Biostimulation at field scale of an RDX‐contaminated area performed by adding acetate as a biostimulant showed a microbial population shift from a microbial community dominated by Betaproteobacteria to a community dominated by Deltaproteobacteria and Bacteroidetes (Livermore et al., ).…”

Section: Discussionmentioning

confidence: 99%

Biostimulation and microbial community profiling reveal insights on RDX transformation in groundwater

et al. 2016

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Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) is a high explosive released to the environment as a result of weapons manufacturing and testing worldwide. At Los Alamos National Laboratory, the Technical Area (TA) 16 260 Outfall discharged high‐explosives‐bearing water from a high‐explosives‐machining facility to Cañon de Valle during 1951 through 1996. These discharges served as a primary source of high‐explosives and inorganic‐element contamination in the area. Data indicate that springs, surface water, alluvial groundwater, and perched‐intermediate groundwater contain explosive compounds, including RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine); HMX (octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine); and TNT (2,4,6‐trinitrotoluene). RDX has been detected in the regional aquifer in several wells, and a corrective measures evaluation is planned to identify remedial alternatives to protect the regional aquifer. Perched‐intermediate groundwater at Technical Area 16 is present at depths from 650 ft to 1200 ft bgs. In this study, we examined the microbial diversity in a monitoring well completed in perched‐intermediate groundwater contaminated by RDX, and examined the response of the microbial population to biostimulation under varying geochemical conditions. Results show that the groundwater microbiome was dominated by Actinobacteria and Proteobacteria. A total of 1,605 operational taxonomic units (OTUs) in 96 bacterial genera were identified. Rhodococcus was the most abundant genus (30.6%) and a total of 46 OTUs were annotated as Rhodococcus. One OTU comprising 25.2% of total sequences was closely related to a RDX ‐degrading strain R. erythropolis HS4. A less abundant OTU from the Pseudomonas family closely related to RDX‐degrading strain P. putida II‐B was also present. Biostimulation significantly enriched Proteobacteria but decreased/eliminated the population of Actinobacteria. Consistent with RDX degradation, the OTU closely related to the RDX‐degrading P. putida strain II‐B was specifically enriched in the RDX‐degrading samples. Analysis of the accumulation of RDX‐degradation products reveals that during active RDX degradation, there is a transient increase in the concentration of the degradation products MNX, DNX, TNX, and NDAB. The accumulation of these degradation products suggests that RDX is degraded via sequential reduction of the nitro functional groups followed by abiotic ring‐cleavage. The results suggest that strict anaerobic conditions are needed to stimulate RDX degradation under the TA‐16 site‐specific conditions.

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“…However, emulsions can also be used to improve sweeping efficiency into lowpermeability layers (e.g., Jung et al 2006;Cobos et al 2009;Guillen et al 2012;Silva et al 2012), to sequester contaminants out of the aqueous phase (e.g., Lee et al 2007Lee et al , 2019, and as a vehicle to deliver reactive amendments (e.g., Quinn et al 2004Quinn et al , 2005Berge and Ramsburg 2009;Muller 2016;Dong et al 2019). For example, reactive iron particles have been encapsulated within emulsions for improved amendment delivery and distribution without compromising reactivity (Quinn et al 2004(Quinn et al , 2005Berge and Ramsburg 2009), and soluble substrates, nutrients, and pH additives have been incorporated into emulsion mixtures of edible oils to support bioremediation (Borden 2006;Muller 2016;Borden et al 2019;Dong et al 2019).…”

Section: Emulsionsmentioning

confidence: 99%

Methods for Delivery and Distribution of Amendments for Subsurface Remediation: A Critical Review

Muller¹,

Johnson²,

Bagwell³

et al. 2020

Groundwater Monitoring Rem

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The ability to reliably deliver and widely distribute remedial amendments through the subsurface environment is of paramount importance to achieve cleanup objectives for contaminated sediments and groundwater for protection of sensitive environmental habitats and natural resources. A wide range of amendments, delivery techniques, and subsurface access methods are available. However, the applicability of these approaches is dependent on a multitude of site‐specific factors. In this review, an overview of amendments and access/distribution methods is provided, along with discussion of the maturity level, advantages, and limitations that relate to the potential effectiveness of each approach in the context of site‐specific factors. Each amendment and delivery approach are further evaluated for applicability to the following subsurface target zones: saturated, unsaturated, and perched water, with specific focus on high and low permeability regions in each zone. The review highlights a critical need for field‐tested approaches targeting unsaturated and perched water zones, as well as low‐permeability regions within all subsurface regions. The intent of this review is to provide critical information and insight into how amendments can be delivered, emplaced, and/or distributed effectively in the subsurface environment to effectively manage subsurface contamination.

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Protocol for Enhanced in situ Bioremediation Using Emulsified Edible Oil

Cited by 9 publications

References 44 publications

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Biostimulation and microbial community profiling reveal insights on RDX transformation in groundwater

Methods for Delivery and Distribution of Amendments for Subsurface Remediation: A Critical Review

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Protocol for Enhanced in situ Bioremediation Using Emulsified Edible Oil

Cited by 9 publications

References 44 publications

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H2-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H2-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Biostimulation and microbial community profiling reveal insights on RDX transformation in groundwater

Methods for Delivery and Distribution of Amendments for Subsurface Remediation: A Critical Review

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Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes

Microbial Chain Elongation and Subsequent Fermentation of Elongated Carboxylates as H₂-Producing Processes for Sustained Reductive Dechlorination of Chlorinated Ethenes