Sequential anaerobic and aerobic bioaugmentation for commingled groundwater contamination of trichloroethene and 1,4-dioxane

Fei Li, Daiyong Deng, Lingke Zeng, Stewart Abrams, Mengyan Li

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Chlorinated solvents, notably trichloroethene (TCE), and the cyclic ether stabilizer, 1,4-dioxane (dioxane), have been frequently detected commingling in contaminated aquifers. Here we developed a sequential anaerobic and aerobic treatment strategy effective to mitigate the co-contamination of TCE and dioxane, particularly when dioxane is present at ppb levels relevant to many impacted sites. After the primary anaerobic treatment by a halorespiring consortium SDC-9, TCE was effectively removed, though lingering less-chlorinated metabolites, vinyl chloride (VC) and cis-dichloroethene (cDCE). Subsequent aerobic bioaugmentation with Azoarcus sp. DD4, a cometabolic dioxane degrader, demonstrated the ability of DD4 to degrade dioxane at an initial concentration of 20 μg/L to below 0.4 μg/L and its dominance (~7%) in microcosms fed with propane. Even better, DD4 can also transform VC and cDCE in tandem, though cDCE and VC at relatively high concentrations (e.g., 1 mg/L) posed inhibition to propane assimilation and cell growth of DD4. Mutagenesis of DD4 revealed group-2 toluene monooxygenase and group-5 propane monooxygenase are responsible for cDCE and VC co-oxidation, respectively. Overall, we demonstrated the feasibility of a treatment train combining reductive dehalogenation and aerobic co-oxidation processes in tandem to not only effectively clean up prevalent co-contamination of TCE and dioxane at trace levels but also mitigate persistent products (e.g., cDCE and VC) when complete reductive dehalogenation of less-chlorinated ethenes occurs slowly in the field.

Original languageEnglish (US)
Article number145118
JournalScience of the Total Environment
StatePublished - Jun 20 2021

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


  • 1,4-Dioxane
  • Bioremediation
  • Cometabolic degradation
  • Reductive dehalogenation
  • Trichloroethene
  • cVOCs


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