In Situ Bioremediation of Energetic Compounds in Groundwater

Hatzinger, Paul B.; Schaefer, Charles E.; Sheehan, Pamela L.; Leeson, Andrea

doi:10.21236/ada569692

Cited by 4 publications

(4 citation statements)

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“…In situ anaerobic bioremediation of RDX (and other explosives) has been demonstrated at several sites (Hatzinger and Lippincott 2012;Michalsen et al 2013;Newell 2008;Wade et al 2010). However, creating and maintaining anaerobic conditions across large areas is costly and technically challenging, indicating a need to pursue other potential solutions, especially for large, dilute plumes.…”

Section: Introductionmentioning

confidence: 99%

Laboratory evaluation of bioaugmentation for aerobic treatment of RDX in groundwater

et al. 2014

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The potential for bioaugmentation with aerobic explosive degrading bacteria to remediate hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated aquifers was demonstrated. Repacked aquifer sediment columns were used to examine the transport and RDX degradation capacity of the known RDX degrading bacterial strains Gordonia sp. KTR9 (modified with a kanamycin resistance gene) Pseudomonas fluorescens I-C, and a kanamycin resistant transconjugate Rhodococcus jostii RHA1 pGKT2:Km+. All three strains were transported through the columns and eluted ahead of the conservative bromide tracer, although the total breakthrough varied by strain. The introduced cells responded to biostimulation with fructose (18 mg L(-1), 0.1 mM) by degrading dissolved RDX (0.5 mg L(-1), 2.3 µM). The strains retained RDX-degrading activity for at least 6 months following periods of starvation when no fructose was supplied to the column. Post-experiment analysis of the soil indicated that the residual cells were distributed along the length of the column. When the strains were grown to densities relevant for field-scale application, the cells remained viable and able to degrade RDX for at least 3 months when stored at 4 °C. These results indicate that bioaugmentation may be a viable option for treating RDX in large dilute aerobic plumes.

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Section: Introductionmentioning

confidence: 99%

Laboratory evaluation of bioaugmentation for aerobic treatment of RDX in groundwater

et al. 2014

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“…In some previous studies at Umatilla and elsewhere, large additions of organic substrate were utilized to create the highly reducing conditions deemed necessary for stimulating anaerobic RDX biodegradation (e.g., refs , ). Results of this field study clearly show that bioaugmentation with low concentration carbon substrate additions can yield at least equivalent RDX removal compared to high carbon biostimulation, while requiring 97% less substrate and reducing secondary groundwater quality impacts caused by anaerobic processes (e.g., production of nitroso-RDX derivatives, dissolved iron and sulfide).…”

Section: Discussionmentioning

confidence: 99%

“…One approach is biostimulation, where exogenous substrates are added to an aquifer to promote the growth of indigenous microorganisms with the ability to degrade the targeted contaminant. Anaerobic RDX biodegradation has been studied for more than 30 years (e.g., ref ), and it is well-accepted that this process can be stimulated in many environments through the addition of organic substrates to generate reducing conditions (e.g., refs , − ). Under anaerobic (primarily iron- and sulfate-reducing) conditions, RDX can be degraded either by sequential reduction of the −N–NO 2 functional groups , to give the corresponding nitroso derivatives MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), DNX (hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine), and TNX (hexahydro-1,3,5-trinitroso-1,3,5-triazine) or by initial cleavage of the −C−N or −N−NO 2 bond(s), leading to eventual formation of nitrite, ammonia, N 2 O, HCHO, and HCOOH .…”

Section: Introductionmentioning

confidence: 99%

“…RDX is transformed by a wide range of facultative and strict anaerobes, such as Klebsiella, Desulfovibrio, Pseudomonas, Geobacter, Clostridium, − and Shewanella, which can use RDX as a terminal electron acceptor for growth. Pilot-scale experiments and full-scale treatment , have demonstrated the feasibility of stimulating the growth of indigenous microorganisms with the ability to degrade RDX under anoxic/anaerobic conditions. However, the cost of creating and maintaining anoxic/anaerobic conditions in an initially aerobic groundwater environment can be high, especially when groundwater contains significant concentrations of competing electron acceptors.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Biostimulation and Bioaugmentation To Stimulate Hexahydro-1,3,5-trinitro-1,3,5,-triazine Degradation in an Aerobic Groundwater Aquifer

Michalsen

King

Rule

et al. 2016

Environ. Sci. Technol.

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Hexahydro-1,3,5-trinitro-1,3,5,-triazine (RDX) is a toxic and mobile groundwater contaminant common to military sites. This study compared in situ RDX degradation rates following bioaugmentation with Gordonia sp. strain KTR9 (henceforth KTR9) to rates under biostimulation conditions in an RDX-contaminated aquifer in Umatilla, OR. Bioaugmentation was achieved by injecting site groundwater (6000 L) amended with KTR9 cells (10(8) cells mL(-1)) and low carbon substrate concentrations (<1 mM fructose) into site wells. Biostimulation (no added cells) was performed by injecting groundwater amended with low (<1 mM fructose) or high (>15 mM fructose) carbon substrate concentrations in an effort to stimulate aerobic or anaerobic microbial activity, respectively. Single-well push-pull tests were conducted to measure RDX degradation rates for each treatment. Average rate coefficients were 1.2 day(-1) for bioaugmentation and 0.7 day(-1) for high carbon biostimulation; rate coefficients for low carbon biostimulation were not significantly different from zero (p values ≥0.060). Our results suggest that bioaugmentation with KTR9 is a feasible strategy for in situ biodegradation of RDX and, at this site, is capable of achieving RDX concentration reductions comparable to those obtained by high carbon biostimulation while requiring ~97% less fructose. Bioaugmentation has potential to minimize substrate quantities and associated costs, as well as secondary groundwater quality impacts associated with anaerobic biostimulation processes (e.g., hydrogen sulfide, methane production) during full-scale RDX remediation.

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A comparative study of microbial communities in four soil slurries capable of RDX degradation using illumina sequencing

Jayamani

Cupples

2015

Biodegradation

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The nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has contaminated many military sites. Recently, attempts to remediate these sites have focused on biostimulation to promote RDX biodegradation. Although many RDX degrading isolates have been obtained in the laboratory, little is known about the potential of microorganisms to degrade this chemical while existing in a soil community. The current study examined and compared the RDX degrading communities in four soil slurries to elucidate the potential of natural systems to degrade this chemical. These soils were selected as they had no previous exposure to RDX, therefore their microbial communities offered an excellent baseline to determine changes following RDX degradation. High throughput sequencing was used to determine which phylotypes experienced an increase in relative abundance following RDX degradation. For this, total genomic DNA was sequenced from (1) the initial soil, (2) soil slurry microcosms following RDX degradation and (3) control soil slurry microcosms without RDX addition. The sequencing data provided valuable information on which phylotypes increased in abundance following RDX degradation compared to control microcosms. The most notable trend was the increase in abundance of Brevundimonas and/or unclassified Bacillaceae 1 in the four soils studied. Although isolates of the family Bacillaceae 1 have previously been linked to RDX degradation, isolates of the genus Brevundimonas have not been previously associated with RDX degradation. Overall, the data suggest these two phylotypes have key roles in RDX degradation in soil communities.

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In Situ Bioremediation of Energetic Compounds in Groundwater

Cited by 4 publications

References 26 publications

Laboratory evaluation of bioaugmentation for aerobic treatment of RDX in groundwater

Laboratory evaluation of bioaugmentation for aerobic treatment of RDX in groundwater

Evaluation of Biostimulation and Bioaugmentation To Stimulate Hexahydro-1,3,5-trinitro-1,3,5,-triazine Degradation in an Aerobic Groundwater Aquifer

A comparative study of microbial communities in four soil slurries capable of RDX degradation using illumina sequencing

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