English Journal

Effects of bioaugmentation on enhanced reductive dechlorination of 1,1,1-trichloroethane in groundwater: a comparison of three sites.

Scheutz C, Durant ND, Broholm MM.Author information Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet - Building 115, 2800, Kongens Lyngby, Denmark, chas@env.dtu.dk.AbstractMicrocosm studies investigated the effects of bioaugmentation with a mixed Dehalococcoides (Dhc)/Dehalobacter (Dhb) culture on biological enhanced reductive dechlorination for treatment of 1,1,1-trichloroethane (TCA) and chloroethenes in groundwater at three Danish sites. Microcosms were amended with lactate as electron donor and monitored over 600 days. Experimental variables included bioaugmentation, TCA concentration, and presence/absence of chloroethenes. Bioaugmented microcosms received a mixture of the Dhc culture KB-1 and Dhb culture ACT-3. To investigate effects of substrate concentration, microcosms were amended with various concentrations of chloroethanes (TCA or monochloroethane [CA]) and/or chloroethenes (tetrachloroethene [PCE], trichloroethene [TCE], or 1,1-dichloroethene [1,1-DCE]). Results showed that combined electron donor addition and bioaugmentation stimulated dechlorination of TCA and 1,1-dichloroethane (1,1-DCA) to CA, and dechlorination of PCE, TCE, 1,1-DCE and cDCE to ethane. Dechlorination of CA was not observed. Bioaugmentation improved the rate and extent of TCA and 1,1-DCA dechlorination at two sites, but did not accelerate dechlorination at a third site where geochemical conditions were reducing and Dhc and Dhb were indigenous. TCA at initial concentrations of 5 mg/L inhibited (i.e., slowed the rate of) TCA dechlorination, TCE dechlorination, donor fermentation, and methanogenesis. 1 mg/L TCA did not inhibit dechlorination of TCA, TCE or cDCE. Moreover, complete dechlorination of PCE to ethene was observed in the presence of 3.2 mg/L TCA. In contrast to some prior reports, these studies indicate that low part-per million levels of TCA (<3 mg/L) in aquifer systems do not inhibit dechlorination of PCE or TCE to ethene. In addition, the results show that co-bioaugmentation with Dhc and Dhb cultures can be an effective strategy for accelerating treatment of chloroethane/chloroethene mixtures in groundwater, with the exception that all currently known Dhc and Dhb cultures cannot treat CA.
Biodegradation.Biodegradation.2013 Nov 14. [Epub ahead of print]
Microcosm studies investigated the effects of bioaugmentation with a mixed Dehalococcoides (Dhc)/Dehalobacter (Dhb) culture on biological enhanced reductive dechlorination for treatment of 1,1,1-trichloroethane (TCA) and chloroethenes in groundwater at three Danish sites. Microcosms were amended wit
PMID 24233554

Carbon isotope fractionation of 1,1,1-trichloroethane during base-catalyzed persulfate treatment.

Marchesi M, Thomson NR, Aravena R, Sra KS, Otero N, Soler A.Author information Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1. m2marche@uwaterloo.caAbstractThe extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S₂O₈(2-)) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S₂O₈(2-) molar ratio from 0.2:1 to 8:1 enhanced the reaction rate of 1,1,1-TCA by a factor of ∼5 to yield complete (>99.9%) destruction. An average carbon isotope enrichment fractionation factor which was independent of the NaOH:S₂O₈(2-) molar ratio of -7.0 ± 0.2‰ was obtained. This significant carbon isotope fractionation and the lack of dependence on changes in the NaOH:S₂O₈(2-) molar ratio demonstrates that carbon isotope analysis can potentially be used in situ as a performance assessment tool to estimate the degradation effectiveness of 1,1,1-TCA by a base-catalyzed persulfate system.
Journal of hazardous materials.J Hazard Mater.2013 Sep 15;260:61-6. doi: 10.1016/j.jhazmat.2013.05.011. Epub 2013 May 14.
The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S₂O₈(2-)) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S₂O₈(2-) molar ratio fro
PMID 23747463

The reductive degradation of 1,1,1-trichloroethane by Fe(0) in a soil slurry system.

Wu X, Lu S, Qiu Z, Sui Q, Lin K, Du X, Luo Q.Author information State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai, 200237, China.AbstractMost studies on the treatment of chlorinated contaminants by Fe(0) focus on aqueous system tests. However, few is known about the effectiveness of these tests for degrading chlorinated contaminants such as 1,1,1-trichloroethane (TCA) in soil. In this work, the reductive degradation performance of 1,1,1-TCA by Fe(0) was thoroughly investigated in a soil slurry system. The effects of various factors including acid-washed iron, the initial 1,1,1-TCA concentration, Fe(0) dosage, slurry pH, and common constituents in groundwater and soil such as Cl-, HCO3 -, SO4 2-, and NO3 - anions and humic acid (HA) were evaluated. The experimental results showed that 1,1,1-TCA could be effectively degraded in 12 h for an initial Fe(0) dosage of 10 g L-1 and a soil/water mass ratio of 1:5. The soil slurry experiments showed two-stage degradation kinetics: a slow reaction in the first stage and a fast reductive degradation of 1,1,1-TCA in the second stage. The reductive degradation of 1,1,1-TCA was expedited as the mass concentration of Fe(0) increased. In addition, high pHs adversely affected the degradation of 1,1,1-TCA over a pH range of 5.4-8.0 and the reductive degradation efficiency decreased with increasing slurry pH. The initial 1,1,1-TCA concentration and the presence of Cl- and SO4 2- anions had negligible effects. HCO3 - anions had a accelerative effect on 1,1,1-TCA removal, and both NO3 - and HA had inhibitory effects. A Cl- mass balance showed that the amount of Cl- ions released into the soil slurry system during the 1,1,1-TCA degradation increased with increasing reaction time, suggesting that the main degradation mechanism of 1,1,1-TCA by Fe(0) in a soil slurry system was reductive dechlorination with 1,1-DCA as the main intermediate. In conclusion, this study provides a theoretical basis for the practical application of the remediation of contaminated sites containing chlorinated solvent.
Environmental science and pollution research international.Environ Sci Pollut Res Int.2013 Aug 1. [Epub ahead of print]
Most studies on the treatment of chlorinated contaminants by Fe(0) focus on aqueous system tests. However, few is known about the effectiveness of these tests for degrading chlorinated contaminants such as 1,1,1-trichloroethane (TCA) in soil. In this work, the reductive degradation performance of 1,
PMID 23904257

Japanese Journal

1, 1, 1-トリクロルエタン曝露の指標としての尿中溶剤濃度と尿中代謝物濃度

水沼一典,河合俊夫,堀口俊一,池田正之
産業衛生学雑誌 = Journal of occupational health 37, S445, 1995-03-20
NAID 10016501089

Interaction between Methylchloroform and Surface Modified Activated Carbon in CF_4 Plasma

TANADA Seiki,TORII Yasuhiro,NAKAMURA Takeo,KAWASAKI Naohito,TOKIMOTO Toshimitsu
Chemistry letters 1994(12), 2373-2376, 1994-12-05
NAID 10006896299

Interaction between Methylchloroform and Surface Modified Activated Carbon in CF4 Plasma.

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Chemistry Letters (12), 2373-2376, 1994
… The interaction between methylchloroform and a surface modified activated carbon, which was treated with tetrafluoromethane plasma, was evaluated on the basis of adsorption isotherms and physicochemical properties of the activated carbon. … Tetrafluoromethane plasma-treated activated carbon could be used for the complete recovery of methylchloroform. …
NAID 130004419279

Related Pictures

Figure imgb0001 Methyl chloroform graph MethylChloroform Example of exponential CarbonTetraChloride; MCF: MethylChloroForm Methylchloroform C 2 H 3 Cl 3 Structural formula of methylchloroform trichloro ethane(methyl chloroform)