Model simulations for <i>in situ</i> aerobic cometabolism of trichloroethylene

Su, Ching‐Tzong; Kuo, Tom Ming-Ching; Liang, Kang; Lin, Chun Yu

doi:10.1002/jctb.2472

Cited by 4 publications

(2 citation statements)

References 27 publications

(36 reference statements)

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“…Kuo et al (2004) conducted a 92‐d pilot test of in situ aerobic cometabolism to evaluate the feasibility of injecting toluene vapor for (1) enhancing the growth of indigenous toluene‐utilizing bacteria that would degrade TCE by aerobic cometabolism and (2) avoiding potential clogging near the injection points. Injecting toluene vapor and air into TCE‐contaminated aquifer, the concentration of toluene dissolved in groundwater was controlled at 3.8 mg/L (Liang and Kuo 2009; Su et al 2010). Throughout the 92‐d test period, both the injection pressure and the flow rate of air remained fairly constant.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Toluene‐Substrate Concentration on Biological Clogging and Sloughing in Porous Media

Cheng¹,

Kuo²

2010

Groundwater Monitoring Rem

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One-dimensional flow experiments on biological clogging were carried out by biostimulating columns packed with glass beads, sterilized, and inoculated with toluene-utilizing bacteria. Biostimulation consisted of continuously injecting toluene at four concentrations (3.0 ± 0.9, 6.1 ± 0.8, 8.7 ± 1.6, and 11.3 ± 0.8 mg/L). The results of column flow experiments indicated that a threshold concentration of toluene exists below which the total biomass in the column can be kept at a steady-state level. The column cores were extruded and segmented to determine the biomass distribution throughout the column at clogging. Clogging resulted in a significant buildup of filamentous bacteria close to the inlet end. Based on the nucleotide sequence of 16S rRNA genes, the dominant filamentous bacteria were identified as Nocardia farcinica. A 235-d column experiment demonstrated that the clogging near injection points can be controlled by keeping the influent concentration of toluene below the threshold.the type of microorganisms involved in the clogging process with microscopic observation; (4) identify the dominant bacteria using molecular methods based on the nucleotide sequence of 16S rRNA genes; and (5) demonstrate that the clogging near injection points can be controlled by keeping the influent toluene concentration below a threshold with a long-term (235 d) column flow experiment. Materials and Methods Bacterial Culture and MediumThe microorganisms used in this study were initially collected from river sand. The microorganisms were then acclimated in a chemostat using toluene as the substrate to grow toluene-utilizing cells. The acclimated cultures were used as the cell source for enrichment with the glucose-limiting nutrient solution as follows (mg/L): glucose, 1000; (NH 4 ) 2 SO 4 , 500; MgSO 4 ·7H 2 O, 100; FeCl 3 ·6H 2 O, 0.5; CaCl 2 , 7.5; MnSO 4 ·H 2 O, 10; KH 2 PO 4 , 527; and K 2 HPO 4 , 1070. The enriched cells were used as inoculum for the column experiment.A one-dimensional (1D) flow experiment on biological clogging was carried out by biostimulating columns packed with glass beads, sterilized, and inoculated with tolueneutilizing bacteria. Biostimulation consisted of continuously injecting nutrient solution and toluene solution as the substrate to grow toluene-utilizing cells. The composition of the nutrient solution was as follows (mg/L): (NH 4 )

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Section: Resultsmentioning

confidence: 99%

The Effect of Toluene‐Substrate Concentration on Biological Clogging and Sloughing in Porous Media

Cheng¹,

Kuo²

2010

Groundwater Monitoring Rem

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“…Microbial aerobic cometabolism is a possible treatment approach for large, dilute TCE plumes. − Heterotrophic bacteria capable of TCE cometabolism under oxic conditions consume a metabolic organic substrate (typically provided in excess), such as methane, ethane, propane, butane, or toluene. These bacteria then degrade TCE by an oxidation reaction forming TCE epoxide. ,,,, Species of Pseudomonas, Burkolderia , Methylosinus , Nitrosomonas , Alcaligenes , Acinetobacter , Mycobacterium , and Nocardioides are known to cometabolize TCE. ,, Mono- and dioxygenases, which are expressed for the utilization of the primary metabolic substrate, also degrade TCE. , Monooxygenases are heme-enzymes that split O 2 and incorporate one O atom into organic compounds; dioxygenases have nonheme iron sulfur groups in their active center and incorporate two O atoms .…”

Section: Introductionmentioning

confidence: 99%

Acetylene Tunes Microbial Growth During Aerobic Cometabolism of Trichloroethene

Skinner,

Palar,

Allen

et al. 2024

Environ. Sci. Technol.

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Microbial aerobic cometabolism is a possible treatment approach for large, dilute trichloroethene (TCE) plumes at groundwater contaminated sites. Rapid microbial growth and bioclogging pose a persistent problem in bioremediation schemes. Bioclogging reduces soil porosity and permeability, which negatively affects substrate distribution and contaminant treatment efficacy while also increasing the operation and maintenance costs of bioremediation. In this study, we evaluated the ability of acetylene, an oxygenase enzyme-specific inhibitor, to decrease biomass production while maintaining aerobic TCE cometabolism capacity upon removal of acetylene. We first exposed propane-metabolizing cultures (pure and mixed) to 5% acetylene (v v–1) for 1, 2, 4, and 8 d and we then verified TCE aerobic cometabolic activity. Exposure to acetylene overall decreased biomass production and TCE degradation rates while retaining the TCE degradation capacity. In the mixed culture, exposure to acetylene for 1–8 d showed minimal effects on the composition and relative abundance of TCE cometabolizing bacterial taxa. TCE aerobic cometabolism and incubation conditions exerted more notable effects on microbial ecology than did acetylene. Acetylene appears to be a viable approach to control biomass production that may lessen the likelihood of bioclogging during TCE cometabolism. The findings from this study may lead to advancements in aerobic cometabolism remediation technologies for dilute plumes.

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